JP2018006168A - Fuel cell system and method for controlling fuel cell system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fuel cell system capable of further improving turbine efficiency, and a method for controlling the fuel cell system.SOLUTION: A fuel cell system comprises an operation state detecting unit which detects an operation state of a fuel cell, and an operation control device which controls a fuel supply device and an oxidant supply device by a signal from the operation state detecting unit. The fuel cell system further comprises a liquid water supply unit which supplies the liquid water discharged from a fuel cell to a combustor. The oxidant supply device comprises a compressor which supplies an oxidant to a cathode electrode of the fuel cell, a turbine which drives the compressor, and a combustor which generates a combustion gas which drives the turbine. The operation control device comprises a liquid water flow rate control unit which controls a combustor supply liquid water flow rate which is a flow rate of the liquid water supplied to the combustor on the basis of a liquid water flow rate control parameter containing any one of load of the fuel cell, target power of the compressor, target recovery power of the turbine, and a target inlet temperature of the turbine.SELECTED DRAWING: Figure 10

Description

  The present invention relates to a fuel cell system and a control method for the fuel cell system.

  Patent Document 1 describes a fuel cell system including an electric turbocharger and a catalytic combustor that supplies combustion exhaust gas to a turbine of the electric turbocharger. In this fuel cell system, anode exhaust gas from the fuel cell is discharged together with liquid water generated by power generation or the like via a purge conduit.

JP 2014-529873 A

  In the fuel cell system of Patent Document 1, the anode exhaust gas is merely sent to the catalytic combustor via the purge conduit, and the supply of liquid water to the turbine is not controlled. Therefore, the turbine efficiency is always sufficiently improved. I couldn't.

  According to an aspect of the present invention, a fuel cell system including a liquid water supply unit that supplies liquid water discharged from a fuel cell to a combustor is provided. The fuel cell system uses a liquid water flow rate control parameter including at least one of a fuel cell load, a compressor target power, a turbine target recovery power, and a turbine target inlet temperature. A liquid water flow rate control unit that controls the flow rate of the supplied liquid water is provided.

  The fuel cell system further includes a liquid water supply unit that supplies liquid water discharged from the fuel cell to the combustor. The operation control device is configured to provide liquid water to be supplied to the combustor based on at least one of the load of the fuel cell, the target power of the compressor, the target recovery power of the turbine, and the target inlet temperature of the turbine. A liquid water flow rate control unit that controls the flow rate of the combustor supply liquid water that is a flow rate is provided.

  According to an aspect of the present invention, liquid water to be supplied to the combustor can be appropriately supplied according to the operating state of the fuel cell, and turbine efficiency can be improved.

FIG. 1 is a schematic configuration diagram of a fuel cell system according to the first embodiment. FIG. 2 is a diagram illustrating the configuration of the combustor. FIG. 3 is a schematic view taken along line XX in FIG. FIG. 4 is a flowchart illustrating an overview of overall control of the fuel cell system according to the first embodiment. FIG. 5 is a flowchart showing a flow of calculation of the target stack current. FIG. 6 is a flowchart showing a flow of calculation of the cooling system operation amount. FIG. 7 is a flowchart showing a flow of calculation of the air system operation amount. FIG. 8 is a flowchart showing a flow of calculation of the fuel system operation amount. FIG. 9 is a flowchart for explaining calculation of main control target values in the control of the fuel cell system. FIG. 10 is a block diagram showing an overview of the overall functions of the controller according to the first embodiment. FIG. 11 is a block diagram showing an outline of control of the hydrogen pressure regulating valve opening degree. FIG. 12 is a block diagram showing an outline of HFR control. FIG. 13 is a block diagram showing an overview of the entire air system control according to the first embodiment. FIG. 14 is a block diagram illustrating detailed functions of the air system control unit according to the first embodiment. FIG. 15 is a block diagram illustrating a function for calculating the turbine inlet air pressure. FIG. 16 is a block diagram showing a turbine efficiency calculation function. FIG. 17 shows an outline of the target motor power table. FIG. 18 is a block diagram illustrating functions of the circulation blower control unit according to the first embodiment. FIG. 19 is a diagram showing a turbine request blower rotation speed map. FIG. 20 is a diagram illustrating the function of the purge valve control unit. FIG. 21 is a schematic configuration diagram of a fuel cell system according to a second embodiment of the present invention. FIG. 22 is a block diagram showing an overview of the overall functions of the controller according to the second embodiment. FIG. 23 is a block diagram illustrating detailed functions of the air system control unit according to the second embodiment. FIG. 24 is a block diagram illustrating functions of the circulation blower control unit according to the second embodiment. FIG. 25 is a block diagram showing an overview of the overall functions of the controller according to the third embodiment. FIG. 26 is a block diagram illustrating detailed functions of the air system control unit according to the third embodiment. FIG. 27 is a block diagram illustrating functions of the circulation blower control unit according to the third embodiment. FIG. 28 is a schematic configuration diagram of a fuel cell system according to the fourth embodiment. FIG. 29 is a block diagram showing an overview of the overall functions of the controller according to the fourth embodiment. FIG. 30 is a block diagram illustrating detailed functions of the air system control unit according to the fourth embodiment. FIG. 31 is a block diagram illustrating functions of the circulation blower control unit according to the fourth embodiment.

  Embodiments of the present invention will be described below with reference to the drawings.

(First embodiment)
FIG. 1 is a schematic configuration diagram of a fuel cell system according to a first embodiment of the present invention.

  As shown, the fuel cell system 100 according to the first embodiment of the present invention includes a fuel cell stack 10, a cathode supply / discharge mechanism 12, an anode supply mechanism 14, a turbocharger 16 having a compressor 64 and a turbine 62. A heating / cooling mechanism 17, an HFR measuring device 18, a load device 19, and a controller 20.

  The fuel cell stack 10 is a stacked battery in which a plurality of fuel cells are stacked. The fuel cell stack 10 receives the supply of the anode gas (hydrogen) from the anode supply mechanism 14 and the supply of the cathode gas (air) from the cathode supply / exhaust mechanism 12 to generate electric power necessary for traveling of the vehicle. This generated electric power is used by various auxiliary machines such as the compressor 64 and a driving motor for driving a wheel (not shown). An HFR measuring device 18 and a load device 19 are connected to the positive terminal and the negative terminal of the fuel cell stack 10.

  The cathode supply / discharge mechanism 12 includes a cathode gas supply passage 22 and a cathode gas discharge passage 24.

  The cathode gas supply passage 22 is a passage through which air supplied to the fuel cell stack 10 flows. One end of the cathode gas supply passage 22 is connected to the intake inlet of the compressor 64, and the other end is connected to the cathode inlet 10 a of the fuel cell stack 10.

  The cathode gas discharge passage 24 is a passage through which cathode exhaust gas discharged from the fuel cell stack 10 flows. One end of the cathode gas discharge passage 24 is connected to the cathode outlet 10 b of the fuel cell stack 10, and the other end is connected to the turbine 62. Although not shown in the figure, a configuration of a gas-liquid separator or the like for discharging moisture contained in the cathode gas discharge passage 24 to the outside of the fuel cell system 100 downstream of the combustor 32 in the cathode gas discharge passage 24. It may be provided.

  The cathode gas supply passage 22 is provided with an air flow meter 26 and an air pressure sensor 28 in order from the upstream. The cathode gas discharge passage 24 is provided with a combustor 32 and a nozzle vane 34 in order from the upstream.

  The air flow meter 26 is provided at the intake inlet of the compressor 64 of the turbocharger 16 in the cathode gas supply passage 22. The air flow meter 26 detects the flow rate of air taken into the compressor 64 (hereinafter also simply referred to as “air flow rate”). A signal of the air flow rate detection value detected by the air flow meter 26 is input to the controller 20.

  The air pressure sensor 28 detects the pressure of the cathode gas supply passage 22 discharged from the compressor 64 (hereinafter also referred to as “air pressure”). A signal of the air pressure detection value detected by the air pressure sensor 28 is input to the controller 20.

  In the cathode gas supply passage 22, a bypass passage 36 connected between the fuel cell stack 10 in the cathode gas discharge passage 24 and the combustor 32 is connected between the compressor 64 and the air pressure sensor 28.

  The bypass passage 36 supplies a part of the air sucked into the cathode gas supply passage 22 by the compressor 64 to the cathode gas discharge passage 24 by bypassing the fuel cell stack 10. A bypass valve 38 is provided in the bypass passage 36.

  The bypass valve 38 adjusts the flow rate of air flowing through the bypass passage 36. The bypass valve 38 is controlled to be opened and closed by the controller 20. For example, when the air flow rate exceeds the air flow rate required for power generation by the fuel cell stack 10, the controller 20 increases the opening degree of the bypass valve 38. As a result, the bypass flow rate increases, and overdrying of the electrolyte membrane in the fuel cell stack 10 is prevented.

  The combustor 32 catalytically burns a mixed gas obtained by mixing hydrogen as a fuel and cathode exhaust gas with a mixer by a catalytic action of platinum or the like, and discharges a gas (combustion exhaust gas) remaining after combustion. Hydrogen is supplied to the combustor 32 from the high-pressure tank 40 of the anode supply mechanism 14. The combustor 32 is supplied with cathode exhaust gas obtained by mixing the cathode exhaust gas from the fuel cell stack 10 and the air from the bypass passage 36. Further, in the present embodiment, the combustor 32 is supplied with liquid water generated by power generation or the like in the fuel cell stack 10 via the purge passage 51. That is, in this embodiment, the purge passage 51 functions as a liquid water supply passage.

  The nozzle vane 34 adjusts the pressure of the combustion exhaust gas supplied to the turbine 62. The opening degree (nozzle lift amount) of the nozzle vane 34 is controlled by the controller 20. When the nozzle vane 34 is open, the cross-sectional area of the inlet channel to the turbine 62 increases, and the pressure loss of the combustion exhaust gas flowing into the turbine 62 from the cathode gas discharge passage 24 becomes relatively small. On the other hand, in the closed state of the nozzle vane 34, the cross-sectional area of the inlet channel to the turbine 62 is relatively reduced, and the pressure loss is increased. In other words, the air pressure can be lowered as the nozzle lift amount increases.

  Next, the anode supply mechanism 14 will be described. The anode supply mechanism 14 in this embodiment includes a high-pressure tank 40, a stack hydrogen supply passage 41, a stack supply hydrogen pressure regulating valve 42, a hydrogen circulation passage 43, a water separator 44, a circulation blower 45, and an ejector 46. A circulating hydrogen pressure sensor 47, a combustor hydrogen supply passage 48, a combustor hydrogen amount adjustment valve 49, and a combustor supply hydrogen pressure detection sensor 50.

  The high-pressure tank 40 is a gas storage container that stores hydrogen supplied to the fuel cell stack 10 and the combustor 32 while maintaining the high-pressure state.

  The stack hydrogen supply passage 41 is a passage for supplying hydrogen discharged from the high-pressure tank 40 to the fuel cell stack 10. One end of the stack hydrogen supply passage 41 is connected to the high-pressure tank 40, and the other end is connected to the ejector 46.

  The stack hydrogen supply passage 41 is provided with a stack supply hydrogen pressure regulating valve 42. The stack supply hydrogen pressure regulating valve 42 is controlled to be opened and closed by the controller 20, and the pressure of hydrogen supplied to the fuel cell stack 10 is adjusted.

  The hydrogen circulation passage 43 is connected to the stack hydrogen supply passage 41 via an ejector 46, and is a passage through which hydrogen is circulated through an anode passage in the fuel cell stack 10 (not shown) through an anode inlet 10c and an anode outlet 10d.

  The water separation device 44 is a device that separates moisture contained in the anode exhaust gas discharged from the anode outlet 10 d of the fuel cell stack 10 into the hydrogen circulation passage 43. That is, the water vapor discharged from the anode outlet 10d is liquefied into liquid water (drain) and separated from other components of the anode exhaust gas. As the water separation device 44, for example, a centrifugal filter or the like is used.

  Further, in the present embodiment, the water separation device 44 is connected to a purge passage 51 that supplies a purge gas mainly composed of separated liquid water and nitrogen to the combustor 32. The purge passage 51 is provided with a purge valve 52 configured as an on / off switching valve. Therefore, by adjusting the duty ratio (valve opening time ratio) of the purge valve 52, the flow rate of the liquid water supplied to the combustor 32 is adjusted along with the purge gas discharge flow rate from the hydrogen circulation passage 43. The duty ratio of the purge valve 52 is controlled by the controller 20. That is, in this embodiment, the purge valve 52 functions as a liquid water supply amount adjustment valve.

  The circulation blower 45 is provided between the water separation device 44 and the ejector 46 in the hydrogen circulation passage 43. The circulation blower 45 circulates hydrogen to the fuel cell stack 10 via the ejector 46.

  The ejector 46 is provided at the junction of the stack hydrogen supply passage 41 and the hydrogen circulation passage 43, and circulates the hydrogen in the hydrogen circulation passage 43 using the negative pressure when the supply hydrogen is accelerated and supplied by the nozzle. It is.

  The circulating hydrogen pressure sensor 47 detects the pressure between the ejector 46 and the fuel cell stack 10 in the hydrogen circulation passage 43 (hereinafter also referred to as “circulating hydrogen pressure”). The circulating hydrogen pressure sensor 47 outputs a signal of the circulating hydrogen pressure detection value to the controller 20.

  The combustor hydrogen supply passage 48 is a passage for supplying a part of hydrogen from the high-pressure tank 40 to the combustor 32. One end of the combustor hydrogen supply passage 48 is branched to communicate with the stack hydrogen supply passage 41, and the other end is connected to the combustor 32.

  The combustor hydrogen supply passage 48 is provided with a combustor hydrogen amount adjusting valve 49 that arbitrarily adjusts the hydrogen supply amount to the combustor 32.

  The combustor hydrogen amount adjustment valve 49 is a valve that appropriately adjusts the hydrogen supply amount to the combustor 32. The opening degree of the combustor hydrogen amount adjustment valve 49 is adjusted by the controller 20. The combustor hydrogen amount adjustment valve 49 can be constituted by, for example, a proportional solenoid.

  The combustor hydrogen supply passage 48 is provided with a combustor supply hydrogen pressure detection sensor 50 that detects the pressure of hydrogen upstream of the combustor hydrogen amount adjustment valve 49. The combustor supply hydrogen pressure detection value signal from the combustor supply hydrogen pressure detection sensor 50 is input to the controller 20.

  Next, a specific mode of supplying hydrogen to the combustor 32 via the above-described combustor hydrogen supply passage 48 and a specific mode of supplying liquid water to the combustor 32 via the purge passage 51 will be described.

  FIG. 2 is a diagram illustrating the configuration of the combustor 32, and FIG. 3 is a schematic view taken along the line XX in FIG. In FIG. 2, an arrow A indicates the direction (gas flow direction) in which the cathode exhaust gas flows. FIG. 3 also shows the temperature distribution in the cross section of the combustor 32.

  The combustor 32 is formed in a substantially cylindrical shape, and communicates with the cathode outlet 10 b of the fuel cell stack 10 via the cathode gas discharge passage 24 on one end side (inflow side) in the cathode exhaust gas flow direction A. Further, the other end side (outflow side) of the cathode exhaust gas flow direction A is connected to the turbine 62 via the cathode gas discharge passage 24.

  The combustor 32 includes, in order from the upstream in the cathode exhaust gas flow direction A, the cathode exhaust gas inlet 32a into which the cathode gas discharge passage 24 flows, the above-described combustor hydrogen supply passage 48, the mixer 54 that mixes the cathode exhaust gas and hydrogen, The above-described purge passage 51, the catalyst layer 56 for burning hydrogen and cathode exhaust gas, and the combustion exhaust gas outlet 32b for discharging the combustion exhaust gas heated by the combustion in the catalyst layer 56 to the cathode gas discharge passage 24 on the turbine 62 side, , Is arranged.

  The combustor hydrogen supply passage 48 has a hydrogen supply port 48 a for supplying hydrogen from the high-pressure tank 40. The hydrogen supply passage 48 for the combustor is arranged so that the hydrogen supply port 48 a enters the combustor 32 in a state where the hydrogen supply port 48 a substantially coincides with the height of the central axis of the combustor 32.

  The mixer 54 mixes the cathode exhaust gas flowing in from the cathode exhaust gas inlet 32 a and the hydrogen supplied from the hydrogen supply port 48 a of the combustor hydrogen supply passage 48. The mixer 54 is configured as a so-called static mixer having a structure suitable for this mixing. Hereinafter, a gas obtained by mixing cathode exhaust gas and hydrogen is simply referred to as “mixed gas”.

  The purge passage 51 has a liquid water supply port 51 a for supplying liquid water from the water separation device 44 into the combustor 32. The purge passage 51 is disposed so as to enter the combustor 32 in a state where the liquid water supply port 51 a is located at a height slightly higher than the axial center axis L of the combustor 32. Further, the purge passage 51 is disposed upstream of the catalyst layer 56 downstream in the gas flow direction with respect to the hydrogen supply port 48 a that supplies hydrogen into the combustor 32.

  Further, as shown in FIG. 3, the liquid water supply port 51 a is located above the maximum temperature line M in the horizontal direction of the combustor 32 and along the maximum temperature line N in the vertical direction. ing. That is, the liquid water supply port 51 a is located at the intersection of the maximum temperature line M and the maximum temperature line N and immediately above the maximum temperature point T where the temperature is highest in the temperature distribution of the cross section of the combustor 32.

  The catalyst layer 56 is configured by, for example, supporting a catalyst such as platinum on a support formed in a honeycomb shape with a zeolite-based material or the like. The catalyst layer 56 catalytically burns the mixed gas. That is, the catalyst layer 56 burns the hydrogen component and the oxygen component in the mixed gas, and the combustion exhaust gas that is a gas component (excessive oxygen, nitrogen, etc.) remaining without reacting is converted into a turbine through the combustion exhaust gas outlet 32b. Flow to 62.

  Further, in the present embodiment, the catalyst layer 56 is in contact with liquid water supplied from the water separation device 44 via the liquid water supply port 51a. Thus, when liquid water contacts the catalyst layer 56, liquid water is vaporized with the combustion energy by the combustion of the hydrogen and oxygen, and converted into water vapor. The obtained water vapor flows into the cathode gas discharge passage 24 on the turbine 62 side together with the combustion exhaust gas. That is, in this embodiment, the combustion exhaust gas generated by combustion contains water vapor generated by vaporization of liquid water.

  Next, the turbocharger 16 will be described. The turbocharger 16 includes an electric motor 60, a turbine 62, and a compressor 64.

  The electric motor 60 is connected to the compressor 64 on one side of the rotary drive shaft 66 and is connected to the turbine 62 on the other side of the rotary drive shaft 66. The electric motor 60 generates power by being driven by rotation by an external force and a function (power running mode) as an electric motor that rotates the compressor 64 by receiving power from a battery (not shown) and the fuel cell stack 10 and the like. It has a function (regeneration mode) as a generator for supplying power to the power source. The electric motor 60 includes a motor case (not shown), a stator that is fixed to the inner peripheral surface of the motor case, and a rotor that is rotatably disposed inside the stator. Can be attached to the unit.

  Further, the electric motor 60 is provided with a motor rotation number sensor 72. The motor rotation speed sensor 72 detects the rotation speed of the electric motor 60. The electric motor rotation speed detection value signal detected by the motor rotation speed sensor 72 is input to the controller 20.

  The turbine 62 is rotationally driven by the combustion exhaust gas supplied from the combustor 32. The turbine 62 outputs this rotational driving force to the compressor 64 via the rotational driving shaft 66. That is, the compressor 64 can be rotated via the rotary drive shaft 66 by the recovered power from the turbine 62. Further, it is possible to assist the driving of the compressor 64 by the electric motor 60 by the recovered power of the turbine 62.

  Furthermore, the electric motor 60 can be regeneratively operated by recovering power beyond the work required for the compressor 64 from the turbine 62 and allowing the electric motor 60 to recover the surplus power. Further, the combustion exhaust gas after being used for driving the turbine 62 is discharged outside the fuel cell system 100 through the turbine exhaust passage 68 or used as waste heat in an arbitrary heat requesting portion in the fuel cell system 100. Is done.

  Further, when the power requirement of the compressor 64 is relatively large and the recovery power by the turbine 62 needs to be increased, the flow rate of the combustion exhaust gas flowing into the turbine 62 (hereinafter also referred to as “turbine inlet flow rate”). The compressor 64 can be suitably powered by increasing the temperature (hereinafter “turbine inlet temperature”) and pressure (hereinafter also referred to as “turbine inlet pressure”). Further, by adjusting the nozzle lift amount of the nozzle vane 34 described above, the recovery power by the turbine 62 can be adjusted by adjusting the pressure of the combustion exhaust gas supplied to the turbine 62.

  The compressor 64 is connected to the electric motor 60 and the turbine 62 via a rotary drive shaft 66. The compressor 64 is rotationally driven via the rotational drive shaft 66 by at least one of the electric motor 60 and the turbine 62, and sucks air into the fuel cell system 100 from the outside. The compressor 64 supplies the sucked air to the cathode electrode of the fuel cell stack 10 through the cathode gas supply passage 22.

  Next, the heating / cooling mechanism 17 will be described. The heating / cooling mechanism 17 includes a cooling water circulation passage 80, a water temperature sensor 82, a cooling water circulation pump 84, a cooling water bypass passage 85, a radiator 86, and a three-way valve 88.

  The coolant circulation channel 80 is a passage through which coolant is circulated in communication with a coolant passage inside the fuel cell stack 10 (not shown) via the coolant inlet 10e and the coolant outlet 10f of the fuel cell stack 10. The cooling water circulating in the cooling water circulation channel 80 is supplied into the fuel cell stack 10 from the cooling water inlet 10e of the fuel cell stack 10 and flows in a direction discharged from the cooling water outlet 10f of the fuel cell stack 10.

  The water temperature sensor 82 is provided in the vicinity of the cooling water outlet 10 f of the fuel cell stack 10 in the cooling water circulation passage 80. The water temperature sensor 82 detects the temperature of cooling water discharged from the fuel cell stack 10 (hereinafter also referred to as “cooling water temperature”). A signal of the detected coolant temperature detected by the water temperature sensor 82 is input to the controller 20.

  The cooling water circulation pump 84 circulates the cooling water in the cooling water circulation channel 80. The output of the cooling water circulation pump 84 is controlled by the controller 20.

  The cooling water bypass passage 85 is a passage provided so that the cooling water bypasses the radiator 86. One end of the cooling water bypass passage 85 is connected between the cooling water circulation pump 84 and the radiator 86 in the cooling water circulation passage 80, and the other end is connected to one end of the three-way valve 88.

  The radiator 86 cools the cooling water temperature to a desired temperature by exchanging heat between the cooling water flowing through the cooling water circulation passage 80 and the outside air. The radiator 86 is provided downstream of the cooling water bypass passage 85 in the cooling water circulation passage 80. The radiator 86 cools the cooling water warmed inside the fuel cell stack 10 by a radiator fan 87. The radiator fan 87 is controlled by the controller 20.

  The three-way valve 88 is provided in a portion where the coolant bypass passage 85 joins in the coolant circulation passage 80 between the radiator 86 and the coolant inlet 10e of the fuel cell stack 10. The three-way valve 88 is a valve that adjusts the flow rate of cooling water flowing to the radiator 86 and the flow rate of cooling water that bypasses the radiator 86.

  The three-way valve 88 allows all the cooling water discharged from the cooling water outlet 10f of the fuel cell stack 10 to flow to the radiator 86 in the fully opened state. On the other hand, the three-way valve 88 flows all the cooling water discharged from the cooling water outlet 10 f of the fuel cell stack 10 in the fully closed state to the cooling water bypass passage 85 without passing through the radiator 86.

  Therefore, the amount of cooling water flowing to the radiator 86 and the amount of cooling water bypassing the radiator 86 can be adjusted by appropriately adjusting the opening degree of the three-way valve 88 according to the cooling request of the fuel cell stack 10 and the like. The opening degree of the three-way valve 88 is controlled by the controller 20.

  The HFR measurement device 18 functions as a wet state acquisition device that acquires the wet state of the electrolyte membrane in the fuel cell stack 10. The HFR measuring device 18 is connected to the fuel cell stack 10 and measures the internal impedance of the fuel cell stack 10 correlated with the wet state of the electrolyte membrane.

  Generally, the lower the water content (moisture) of the electrolyte membrane, that is, the dryr the electrolyte membrane, the greater the internal impedance. On the other hand, the higher the moisture content of the electrolyte membrane, that is, the wetter the electrolyte membrane, the smaller the internal impedance. For this reason, in this embodiment, the internal impedance of the fuel cell stack 10 is used as a parameter indicating the wet state of the electrolyte membrane.

  The HFR measurement device 18 supplies, for example, a high-frequency alternating current suitable for detecting the electrical resistance of the electrolyte membrane, and divides the amplitude of the output alternating voltage by the amplitude of the alternating current. Calculate internal impedance.

  Hereinafter, the internal impedance calculated based on the high-frequency AC voltage and AC current is also referred to as HFR (High Frequency Resistance). The HFR measurement device 18 outputs the calculated HFR value to the controller 20 as an HFR measurement value.

  The load device 19 is driven by receiving the generated power supplied from the fuel cell stack 10. Examples of the load device 19 include various auxiliary machines such as a travel motor and an electric motor 60 that drive the vehicle.

  The load device 19 outputs electric power necessary for the operation to the controller 20 as required electric power for the fuel cell stack 10.

  A current sensor 91 and a voltage sensor 92 are disposed between the load device 19 and the fuel cell stack 10.

  The current sensor 91 is connected to a power supply line between the positive terminal of the fuel cell stack 10 and the positive terminal of the load device 19. The current sensor 91 detects a current output from the fuel cell stack 10 to the load device 19. Hereinafter, the current output from the fuel cell stack 10 to the load device 19 is also referred to as “stack current”. The current sensor 91 outputs a stack current detection value signal to the controller 20.

  The voltage sensor 92 is connected between the positive terminal and the negative terminal of the fuel cell stack 10. The voltage sensor 92 detects an inter-terminal voltage that is a voltage between the positive terminal and the negative terminal. Hereinafter, the terminal voltage of the fuel cell stack 10 is referred to as “stack voltage”. The voltage sensor 92 outputs a stack voltage detection value signal to the controller 20.

  Further, the fuel cell system 100 configured as described above has a controller 20 that controls the system in an integrated manner.

  The controller 20 includes a microcomputer that includes a central processing unit (CPU), a read-only memory (ROM), a random access memory (RAM), and an input / output interface (I / O interface).

  Signals from various sensors and measurement devices of the fuel cell system 100 are input to the controller 20. Specifically, the controller 20 includes an HFR measuring device 18, an air flow meter 26, an air pressure sensor 28, a circulating hydrogen pressure sensor 47, a combustor supply hydrogen pressure detection sensor 50, a motor rotation speed sensor 72, a water temperature sensor 82, a current sensor. 91 and a signal from the voltage sensor 92 are input.

  Further, the controller 20 receives a signal of required power corresponding to the load by the load device 19 connected to the fuel cell stack 10 from the operation control device of the load device 19. For example, when the detection signal indicating the amount of depression of the accelerator pedal detected by an accelerator pedal sensor (not shown) increases, the required power of the load device 19 increases, so the signal level of the power generation request signal input to the controller 20 increases. . Then, the controller 20 calculates a target stack current, which is a target value of the stack current, from the calculated required power based on a predetermined IV characteristic of the fuel cell stack 10 and the like.

  The controller 20 determines the nozzle lift amount of the nozzle vane 34, the opening degree of the bypass valve 38, the opening degree of the stack supply hydrogen pressure regulating valve 42, the output (rotation speed) of the circulation blower 45, the combustor hydrogen based on the above input signals and the like. The opening degree of the quantity adjusting valve 49, the duty ratio of the purge valve 52, the output (torque) of the electric motor 60, the rotational speed of the radiator fan 87, and the opening degree of the three-way valve 88 are controlled.

  FIG. 4 is a flowchart showing an outline of overall control of the fuel cell system 100 according to the present embodiment.

  As illustrated, in step S <b> 100, the controller 20 reads a request power signal from the load device 19.

  In step S110, the controller 20 calculates a target stack current.

  FIG. 5 is a flowchart showing a flow of calculation of the target stack current.

  As illustrated, in step S111, the controller 20 estimates the power consumption of the auxiliary machine. Specifically, the controller 20 calculates an estimated value of the power consumption of the electric motor 60 from the detected value of the electric motor rotation speed by the motor rotation speed sensor 72 and the like. Further, the power consumption estimated value of the auxiliary machine may be a value obtained by adding the power consumption of other actuators such as the cooling water circulation pump 84 and the combustor hydrogen amount adjusting valve 49 or the estimated value thereof to the estimated power consumption of the electric motor 60. good.

  In step S112, the controller 20 calculates the target stack power. Specifically, the target stack power is calculated by adding the estimated value of the auxiliary machine power consumption calculated in step S111 to the system required output as the running power based on the operation amount of the accelerator pedal, which is included by the load device 19. Is calculated.

  In step S113, the controller 20 calculates the actual stack power. Specifically, the controller 20 calculates the actual stack power by multiplying the stack current detection value by the current sensor 91 and the stack voltage detection value by the voltage sensor 92.

  In step S114, the controller 20 calculates a target stack current. Specifically, the controller 20 determines the target stack current so that the actual stack power calculated in step S113 approaches the target stack power calculated in step S112 while referring to the IV characteristics.

  Returning to FIG. 4, when the target stack current is calculated in step S110, the calculation of the cooling system operation amount in step S120, the calculation of the air system operation amount in step S130, and the calculation of the fuel system operation amount in step S140 are performed.

  FIG. 6 is a flowchart showing a flow of calculation of the cooling system operation amount. In addition, the process of this flowchart is corresponded to the process of wet control part B102 etc. of FIG.

  As shown in the figure, in step S121, from the viewpoint of suitably controlling the wet state of the electrolyte membrane of the fuel cell stack 10, the controller 20 calculates the target value by which the HFR measurement value by the HFR measuring device 18 is calculated based on the target stack current. The wet control required target air flow rate is calculated so as to approach HFR.

  In step S122, the controller 20 calculates the operation amount of each actuator. Specifically, based on the target HFR, the controller 20 calculates a target radiator fan speed that is a target value of the radiator fan speed and a target three-way valve opening that is a target value of the opening of the three-way valve 88.

  FIG. 7 is a flowchart showing a flow of calculation of the air system operation amount. Note that the processing in this flowchart corresponds to the processing described with reference to FIG.

  As illustrated, in step S131, the controller 20 calculates a target air pressure that is a target value of the air pressure from the target stack current based on a predetermined table.

  In step S132, the controller 20 calculates a target air flow rate that is a target value of the air flow rate from the target stack current in consideration of the wet control required target air flow rate based on a predetermined table.

  In step S133, the controller 20 calculates the operation amount of each actuator. Specifically, the controller 20 sets the target air pressure calculated in step S131, the target air flow rate calculated in step S132, the air flow rate detection value by the air flow meter 26, the turbine inlet temperature previous value described later, and the air pressure by the air pressure sensor 28. Based on the pressure detection value, the command nozzle lift amount of the nozzle vane 34 and the command torque of the electric motor 60 are calculated.

  In step S <b> 134, the controller 20 calculates a target turbine inlet temperature that is a target value of the temperature of the combustion exhaust gas (turbine inlet temperature) in the vicinity of the inlet of the turbine 62. Specifically, the controller 20 determines the command torque of the electric motor 60 calculated in step S133, the detected value of the electric motor rotation speed by the motor rotation speed sensor 72, the target stack current, the target air pressure calculated in step S131, and Based on the target air flow calculated in step S132, the target turbine inlet temperature is calculated.

  FIG. 8 is a flowchart showing a flow of calculation of the fuel system operation amount. Note that the processing in this flowchart corresponds to the processing described with reference to FIGS. 11, 18, and 20 described later.

  As illustrated, in step S <b> 141, the controller 20 determines the target stack that is the target value of the opening of the stack supply hydrogen pressure regulating valve 42 based on the target stack current and the circulating hydrogen pressure detection value from the circulating hydrogen pressure sensor 47. The supply hydrogen pressure regulating valve opening is calculated.

  Specifically, the controller 20 calculates a target circulating hydrogen pressure that is a target value of the circulating hydrogen pressure determined from the viewpoint of suitably controlling the hydrogen concentration in the hydrogen circulation passage 43 based on the target stack current. The controller 20 then opens the target stack supply hydrogen pressure regulating valve from the calculated target circulating hydrogen pressure and the circulating hydrogen pressure detection value using a predetermined feedback controller (hydrogen pressure control unit B101 in FIG. 11) such as a PI controller. Calculate the degree.

  In step S142, the controller 20 calculates the target circulation blower rotation speed based on the target stack current, the detected coolant temperature value from the water temperature sensor 82, the target turbine inlet temperature calculated in step S134, and the target air flow rate. .

  The target circulation blower rotational speed is also described as a desired hydrogen flow rate in the hydrogen circulation passage 43 (hereinafter referred to as “circulation hydrogen flow rate”) from the viewpoint of suitably controlling the power generation of the fuel cell stack 10 and the turbine inlet temperature. ) To achieve the target value of the circulating blower rotation speed.

  Specifically, the controller 20 calculates a power generation request target blower rotational speed as a target value of the circulating blower rotational speed determined from the viewpoint of power generation from the target stack current and the coolant temperature detection value based on a predetermined map. Then, the controller 20 calculates a turbine required target blower rotational speed as a target value of the circulating blower rotational speed determined from the viewpoint of controlling the turbine inlet temperature, from the estimated turbine inlet temperature calculated based on the target turbine inlet temperature. Further, the controller 20 calculates a target circulation blower rotational speed based on the power generation required target blower rotational speed and the turbine required target blower rotational speed.

  In step S143, the controller 20 calculates a target purge valve duty ratio from the target stack current and the coolant temperature detection value based on a predetermined map. The target purge valve duty ratio is determined from the viewpoint of suitably controlling the hydrogen concentration in the anode electrode of the fuel cell stack 10 while suitably controlling the flow rate of the liquid water supplied to the combustor 32 ( This is the target value of the valve opening time ratio.

  Returning to FIG. 4, in step S150, the controller 20 controls the operation amount of the cooling system actuator calculated in step S122, the operation amount of the air system actuator calculated in step S133, and the fuel calculated in steps S141 to S144. The cooling system actuator, the air system actuator, and the fuel system actuator are controlled based on the operation amount of the system actuator.

  Next, in the control described with reference to FIGS. 4 to 8 according to the fuel cell system 100 of the present embodiment, particularly when liquid water is supplied to the combustor 32 via the purge passage 51, the control of the liquid water supply flow rate is performed. The calculation of the main control target value will be described.

  FIG. 9 is a flowchart for explaining calculation of main control target values in the control of the fuel cell system 100 according to the present embodiment.

  First, in step S210, the controller 20 calculates a target stack supply hydrogen pressure regulating valve opening based on the target stack current and the circulating hydrogen pressure (see the hydrogen pressure control unit B101 in FIG. 10 and the like).

  Next, in step S220, the controller 20 determines the target air flow rate, the target turbine inlet based on the target stack current, the air pressure detection value, the air flow rate detection value, the motor rotation speed detection value, the wet control required target air flow rate, and the like. The temperature, the command nozzle lift amount, and the command electric motor torque are calculated (air system FB control unit B103 in FIG. 10).

  In step S230, the controller 20 calculates the wet control required target air flow rate, the target radiator fan rotational speed, and the target three-way valve opening based on the target stack current and the HFR measurement value (wet control unit B102 in FIG. 10). ).

  In step S240, the controller 20 calculates the target circulation blower rotation speed (circulation blower control unit B104 in FIG. 10).

  In step S250, the controller 20 calculates a target purge valve opening based on the target stack current and the coolant temperature detection value.

  In step S260, the controller 20 calculates a target combustion hydrogen supply valve opening based on the target air flow rate and the target turbine inlet temperature (combustor hydrogen amount control unit B106 in FIG. 10).

  Next, various controls in the fuel cell system 100 according to the present embodiment will be described in detail with reference to the block diagrams shown in FIGS. The functions of the blocks shown in FIGS. 10 to 20 are realized by the controller 20.

  FIG. 10 is a block diagram showing an overview of the overall functions of the controller 20 in the fuel cell system 100.

  As illustrated, the controller 20 includes a hydrogen pressure control unit B101, a wetting control unit B102, an air system FB control unit B103, a circulation blower control unit B104, a purge valve control unit B105, and a combustor hydrogen amount control unit. B106.

  The target stack current and the circulating hydrogen pressure detection value are input to the hydrogen pressure control unit B101. The hydrogen pressure control unit B101 controls the opening degree of the stack supply hydrogen pressure regulating valve 42 based on the target stack current and the circulating hydrogen pressure detection value.

  FIG. 11 is a block diagram illustrating the function of the hydrogen pressure control unit B101. As illustrated, the hydrogen pressure control unit B101 includes a target circulation hydrogen pressure calculation unit B1011 and a stack supply hydrogen pressure regulating valve FB control unit B1012.

  A target stack current is input to the target circulating hydrogen pressure calculation unit B1011. The target circulating hydrogen pressure calculation unit B1011 calculates the target circulating hydrogen pressure from the target stack current based on a map that shows a predetermined relationship between the target stack current and the target circulating hydrogen pressure. In this map, the target circulating hydrogen pressure increases as the target stack current increases. As a result, the target circulating hydrogen pressure is set to a higher value as the load required for the fuel cell stack 10 increases.

  The target circulating hydrogen pressure and the circulating hydrogen pressure detection value are input to the stack supply hydrogen pressure regulating valve FB control unit B1012. The stack supply hydrogen pressure regulating valve FB control unit B1012 feedback-controls the opening degree of the stack supply hydrogen pressure regulating valve 42 so that the detected circulating hydrogen pressure value approaches the target circulating hydrogen pressure.

  Returning to FIG. 10, the target stack current and the measured HFR value are input to the wetting control unit B102. The wetting control unit B102 calculates the wetting control request target air flow rate based on the target stack current and the HFR measurement value, and controls the rotational speed of the radiator fan 87 and the opening degree of the three-way valve 88.

  FIG. 12 is a block diagram illustrating functions of the wetness control unit B102. As illustrated, the wetting control unit B102 includes a target HFR calculation unit B1021 and an FB control unit B1022.

  The target stack current is input to the target HFR calculation unit B1021. The target HFR calculating unit B1021 calculates the target HFR from the target stack current based on a map that shows a predetermined relationship between the target stack current and the target HFR. In this map, the target HFR is set to a constant value in order to keep the HFR value constant between the low load region and the medium load region where the target stack current takes a relatively low value. On the other hand, in the high load region, the target HFR is set to be lower as the target stack current increases. This is because in a high load region, it is required to maintain the wetness of the electrolyte membrane of the fuel cell stack 10 in a higher state, and thus the HFR is reduced according to this requirement.

  A value obtained by subtracting the HFR measurement value from the target HFR (hereinafter referred to as an HFR deviation) is input to the FB control unit B1022. The FB control unit B1022 calculates the wet control request target flow rate so that the input HFR deviation becomes zero, and controls the rotation speed of the radiator fan 87 and the opening degree of the three-way valve 88.

  The FB control unit B1022 calculates the wet control target air flow rate from the HFR deviation based on a map that shows a predetermined relationship between the HFR deviation and the wet control target air flow rate. Specifically, the FB control unit B1022 calculates the wet control target air flow rate to a lower value in order to decrease the HFR value (to control the electrolyte membrane to the wet side) as the HFR deviation decreases.

  Further, the FB control unit B1022 controls the rotation speed of the radiator fan 87 based on the HFR deviation. That is, the FB control unit B1022 increases the rotational speed of the radiator fan 87 so that the cooling water temperature becomes lower in order to reduce the HFR (in order to control the electrolyte membrane to the wet side) as the HFR deviation becomes smaller. .

  Further, the FB control unit B1022 controls the opening degree of the three-way valve 88 based on the HFR deviation. That is, the FB control unit B1022 increases the opening degree of the three-way valve 88 so that the cooling water temperature becomes lower in order to increase the HFR (to control the electrolyte membrane to the wet side) as the HFR deviation becomes smaller. .

  As already described, in the wetness control unit B102 in the present embodiment, the target HFR value is decreased in order to maintain the wetness of the electrolyte membrane of the fuel cell stack 10 in a higher load region. Therefore, since the HFR measurement value is larger than the target HFR and the operation of wetting the electrolyte membrane of the fuel cell stack 10 tends to be required, an increase in the rotational speed of the radiator fan 87 and the opening of the three-way valve 88 are likely to occur. Operations such as increasing the cooling water temperature are performed. Thereby, the amount of moisture discharged from the anode outlet 10d of the fuel cell stack 10 can be increased.

  Returning to FIG. 10, the air system FB control unit B <b> 103 receives an air pressure detection value, an air flow rate detection value, an electric motor rotation speed detection value, and a target turbine inlet temperature previous value described later.

  The air system FB control unit B103 calculates a target air flow rate and a target turbine inlet temperature based on these values. The air system FB control unit B103 controls the nozzle lift amount of the nozzle vane 34 and the torque of the electric motor 60 based on these values.

  FIG. 13 is a block diagram showing an overview of the entire air system control in the air system FB control unit B103. As illustrated, the air system FB control unit B103 includes a target air pressure calculation unit B1031, a target air flow rate calculation unit B1032, a maximum selection unit B1033, an air system control unit B1034, and a minimum selection unit B1035. doing.

  The target stack current is input to the target air pressure calculation unit B1031. The target air pressure calculation unit B1031 calculates a target air pressure from the target stack current based on a map indicating a predetermined relationship between the target stack current and the target air pressure. In this map, the target air pressure is set to a higher value as the target stack current increases, that is, as the load on the fuel cell stack 10 increases. Further, the target air pressure calculation unit B1031 outputs the calculated target air pressure to the air system control unit B1034.

  The target air pressure output to the air system control unit B 1034 is set to an upper limit value according to various requirements in the system such as a request for wetting the electrolyte membrane in the fuel cell stack 10 and a request for dilution for diluting the anode exhaust gas. It can also be corrected to take a lower limit.

  A target stack current is input to the target air flow rate calculation unit B1032. The target air flow rate calculation unit B 1032 calculates a power generation request target air flow rate from the target stack current based on a map indicating a relationship between a predetermined target stack current and a target air flow rate. The power generation request target air flow rate is a target value of the air flow rate determined from the viewpoint of satisfying the air flow rate required according to the power generation amount of the fuel cell stack 10. Therefore, in this map, the power generation request target air flow rate is set to a higher value as the target stack current increases, that is, as the load on the fuel cell stack 10 increases. Furthermore, the target air flow rate calculation unit B 1032 outputs the calculated power generation request target air flow rate to the max selection unit B 1033.

  The power generation request target air flow rate and the wet control request air flow rate are input to the Max Select unit B1033. The maximum select unit B1033 outputs the larger one of the power generation request target air flow rate and the wet control request air flow rate to the air system control unit B1034 as the final target air flow rate.

  A target stack current, a target air pressure, a target air flow rate, an air flow rate detection value, a turbine inlet temperature previous value, an electric motor rotation speed detection value, and an air pressure detection value are input to the air system control unit B 1034.

  The air system control unit B 1034 calculates the target turbine inlet temperature based on these input values, and the air system control unit B 1034 controls the opening degree of the nozzle vane 34 and the torque of the electric motor 60.

  FIG. 14 is a block diagram illustrating detailed functions of the air system control unit B 1034. As illustrated, the air system control unit B 1034 includes a turbine recovery power estimation unit B201, a calculation unit B202, an air system actuator control unit B203, a calculation unit B204, a target motor power calculation unit B205, and a recovery power / temperature. Conversion unit B206.

  As shown in the figure, the detected air pressure value, the detected air flow rate, and the previous target turbine inlet temperature are input to the turbine recovery power estimation unit B201. The turbine recovery power estimation unit B201 calculates an estimated value of turbine recovery power (hereinafter also referred to as “estimated turbine recovery power”) from these values and the previous value of the turbine inlet temperature stored in a storage unit (not shown).

Specifically, first, the turbine recovery power estimation unit B201 obtains an estimated turbine inlet temperature _{Tt_in_e} that is an estimated value of the turbine inlet temperature using an approximate expression (1) of a temporary delay in the discrete system shown below.

ただし、
Ｔｔ_{_in_e}(ｎ−1)：タービン入口温度前回値[℃]
Ｔｔ_{_in_t}：目標タービン入口温度前回値[℃]
ｔｓ：時定数［sec］
ｔ_samp：制御演算周期［sec］
である。なお、時定数ｔｓは、実験等により予め定められる。

However,
_{Tt_in_e} (n-1): Turbine inlet temperature previous value [° C]
_{Tt_in_t} : Target turbine inlet temperature previous value [° C]
ts: Time constant [sec]
t _samp : Control calculation cycle [sec]
It is. The time constant ts is determined in advance by experiments or the like.

Then, the turbine recovery power estimation unit B201 calculates an estimated turbine recovery power that is an estimated value of the turbine recovery power from the estimated turbine inlet temperature _{Tt_in_e} . Specifically, the turbine recovery power estimation unit B201 calculates an estimated turbine recovery power PO _{t_e} based on the following equation (2).

ただし、
ＰＯ_{t_e}：推定タービン回収動力 [kW]
Ｑ_in：空気流量検出値[NL/min]
Ｍ_air：空気の式量[g/mol]
ｃｐ_air：空気の定圧比熱[kJ/(g・K)]
Ｖ_sta：標準状態における体積（＝２２．４１４）[L]
η_cp：タービン効率
Ｔ_{t_in_e}：推定タービン入口温度[℃]
Ｔ_sta：標準状態における絶対温度（＝２７３．１５）[K]
Ｐ_{t_in}：タービン入口空気圧力[kPa＿a]
Ｐ_{t_out}：タービン出口空気圧力[ｋPa_a]
γ：比熱比
６０：秒分間の単位変換係数
１０００：ｍ³とＬ（リットル）の単位変換係数
である。

However,
PO _{t_e} : Estimated turbine recovery power [kW]
Q _in : Air flow rate detection value [NL / min]
M _air : Formula amount of air [g / mol]
cp _air : constant-pressure specific heat of air [kJ / (g · K)]
V _sta : Volume in standard state (= 22.414) [L]
η _cp : turbine efficiency T _{t_in_e} : estimated turbine inlet temperature [° C]
T _sta : Absolute temperature in the standard state (= 273.15) [K]
P _{t_in} : Turbine inlet air pressure [kPa_a]
P _{t_out} : Turbine outlet air pressure [kPa_a]
γ: Specific heat ratio 60: Unit conversion coefficient per second 1000: Unit conversion coefficient of m ³ and L (liter).

The turbine inlet air pressure _{Pt_in} is calculated based on the detected air pressure value and the detected air flow rate.

FIG. 15 is a block diagram illustrating a calculation function of the turbine inlet air pressure _{Pt_in} . The turbine recovery power estimation unit B201 has a pressure loss calculation block B301 and a calculation unit B302 shown in the drawing as functions for calculating the turbine inlet air pressure _{Pt_in} .

  An air flow rate detection value is input to the pressure loss calculation block B301. The pressure loss calculation block B301 has a pressure loss table indicating the relationship between the air flow rate and the pressure loss ΔP. Based on the pressure loss table, the pressure loss calculation block B301 calculates a pressure loss ΔP from the input air flow rate detection value, and outputs the pressure loss ΔP to the calculation unit B302.

The air pressure detection value and the pressure loss ΔP are input to the calculation unit B302. The calculation unit B302 outputs a value obtained by subtracting the pressure loss ΔP from the detected air pressure value as the turbine inlet air pressure _{Pt_in} .

For example, atmospheric pressure ( _≈101 [kpa]) is used as the turbine outlet air pressure _{Pt_out} . When the outside air pressure fluctuates, the detected pressure value detected by an atmospheric pressure sensor (not shown) may be used as the turbine outlet air pressure _{Pt_out} .

The turbine efficiency η _cp is calculated based on the turbine inlet air pressure _{Pt_in} and the turbine outlet air pressure _{Pt_out} .

FIG. 16 is a block diagram illustrating a function of calculating the turbine efficiency η _cp . Turbine recovered power estimation unit B201 is a function for calculating the turbine efficiency eta _cp, has a computing unit B401 shown, the turbine efficiency calculation block B 402, the.

The turbine inlet air pressure _{Pt_in} and the turbine outlet air pressure _{Pt_out} are input to the calculation unit _B401 . The calculation unit _B401 calculates the air pressure ratio _{Pt_in} / _{Pt_out} and outputs a turbine efficiency calculation block _B402 .

The turbine pressure calculation block _B402 receives the air pressure ratio _{Pt_in} / _{Pt_out} . Turbine efficiency calculating block B402 includes a turbine efficiency map showing the relationship between air pressure ratio Pt _{_in} / Pt _{_out} and turbine efficiency eta _cp. The turbine efficiency calculation block _B402 calculates the turbine efficiency η _cp from the input air pressure ratio _{Pt_in} / _{Pt_out} based on the turbine efficiency map.

Returning to FIG. 14, the turbine recovery power estimation unit B201 outputs the calculated estimated turbine recovery power PO _{t_e} to the calculation unit B202. By using the estimated turbine recovery power PO _{t_e} as described above, the target turbine inlet temperature determined from the detected values of the air flow rate and the electric motor rotation number as shown in FIG. Since the estimated turbine inlet temperature in consideration of the value is used, it is possible to suppress a delay in control response to the nozzle vane 34 and the electric motor 60.

The estimated turbine recovery power PO _{t_e} and the electric motor rotation speed detection value from the motor rotation speed sensor 72 are input to the calculation unit B202. The calculation unit B202 calculates an estimated value of the turbine recovery torque (hereinafter also referred to as “estimated turbine recovery torque”) by dividing the detected value of the electric motor rotation speed from the estimated turbine recovery power PO _{t_e} . Then, the calculation unit B202 outputs the calculated estimated turbine recovery torque to the subtraction unit 300.

  A target air pressure, a target air flow rate, an air pressure detection value, and an air flow rate detection value are input to the air system actuator control unit B203. The air system actuator controller B203 calculates the command nozzle lift amount and the target compressor torque so that the input air pressure detection value and the air flow rate detection value approach the target air pressure and the target air flow rate, respectively.

  In addition, the air actuator control unit B203 outputs the calculated command nozzle lift amount to the nozzle vane 34 and outputs the calculated target compressor torque to the subtraction unit 300.

  The subtraction unit 300 outputs a value obtained by subtracting the estimated turbine recovery torque calculated by the calculation unit B202 from the target compressor torque calculated by the air system actuator control unit B203 to the electric motor 60 as the electric motor command torque.

  The calculation unit B204 receives the target compressor torque and the electric motor rotation speed detection value calculated by the air actuator control unit B203. The calculation unit B204 multiplies the target compressor torque by the electric motor rotation speed detection value to calculate a target compressor power that is a target value of the power of the compressor 64. That is, the target compressor power corresponds to a target value of the power of the electric motor 60 when the assistance by the turbine 62 is not considered.

  A target stack current is input to the target motor power calculation unit B205. The target motor power calculation unit B205 calculates the target motor power based on the target motor power table indicating the relationship between the target stack current and the target motor power that is an output required for the electric motor 60.

  FIG. 17 shows an outline of the target motor power table. In the map shown in the figure, in this embodiment, the target motor power is set to a constant value until the target stack current increases and reaches I0, that is, until the load increases to a constant value. Thereby, when the required power to the compressor 64 in the low load region or the like is lower than the target motor power, the target turbine recovery power becomes negative, and the fuel supply to the combustor 32 is stopped.

  In the present embodiment, after the target stack current reaches I0, the power generated by the electric motor 60 is reduced and compensated with the recovered power from the turbine 62, thereby reducing the power consumption of the electric motor 60. To do. For this reason, the target motor power is reduced. The target motor power calculation unit B205 calculates the target motor power from this table.

  Returning to FIG. 14, the target motor power calculation unit B205 outputs the calculated target motor power.

  The subtractor 302 subtracts the target motor power calculated by the target motor power calculator B205 from the target compressor power calculated by the calculator B204 to calculate the target turbine recovery power. The subtraction unit 302 outputs the target turbine recovery power to the recovery power / temperature conversion unit B206.

  The target turbine recovery power, the target air pressure, and the target air flow rate are input to the recovery power / temperature conversion unit B206.

  The recovery power / temperature conversion unit B206 calculates the target turbine inlet temperature based on the target turbine recovery power, the target air pressure, and the target air flow rate. Specifically, the recovery power / temperature conversion unit B206 calculates the target turbine inlet temperature from the target turbine recovery power, the target air pressure, and the target air flow rate using the equation (2) used in the turbine recovery power estimation unit B201. To do.

That is, the target turbine recovery power is substituted for PO _{t_e} in the equation (2), and the target air flow rate is substituted for Q _in . Then, in the calculation logic of the turbine inlet air pressure P _{t_in} shown in FIG. 15, the “air pressure detection value” and the “air flow rate detection value” are respectively replaced with the target air pressure and the target air flow rate, and the calculation logic is followed. A turbine inlet air pressure P _{t_in} is calculated. Further, atmospheric pressure is used as the turbine outlet air pressure P _{t_out} .

If each value obtained in this way is applied to Equation (2), T _{t_in_e} in Equation (2) can be obtained, and this can be used as the target turbine inlet temperature.

  The recovery power / temperature conversion unit B206 outputs the calculated target turbine inlet temperature to the minimum selection unit B1035.

  Returning to FIG. 13, the target turbine inlet temperature and the allowable upper limit temperature output from the air system control unit B 1034 are input to the minimum selection unit B 1035. Here, the allowable upper limit temperature is the upper limit temperature of the turbine inlet temperature determined in consideration of the heat-resistant temperature of parts.

  The minimum select unit B1035 outputs the smaller value of the target turbine inlet temperature and the allowable upper limit temperature to the circulation blower control unit B104 and the combustor hydrogen amount control unit B106 as the actual target turbine inlet temperature. Hereinafter, this “actual target turbine inlet temperature” is simply referred to as “target turbine inlet temperature”.

  Returning to FIG. 10, the target stack current, the detected coolant temperature, the target turbine inlet temperature, and the target air flow rate are input to the circulation blower control unit B104. The circulation blower control unit B104 controls the output of the circulation blower 45 based on these values.

  FIG. 18 is a block diagram illustrating functions of the circulation blower control unit B104. The circulation blower control unit B104 includes a power generation request target rotational speed calculation unit B1041, a first-order lag filter B1042, a turbine required target rotational speed calculation unit B1043, and a max selection unit B1044.

  The target stack current and the coolant temperature are input to the power generation request target rotation speed calculation unit B1041. The power generation request target rotation speed calculation unit B1041 generates the power generation request target blower rotation from the target stack current and the cooling water temperature based on a predetermined map indicating the relationship between the target stack current, the cooling water temperature, and the power generation request target blower rotation speed. Calculate the number. Here, the power generation request target blower rotational speed is a target value of the rotational speed of the circulation blower 45 required from the viewpoint of appropriately maintaining the power generation amount of the fuel cell stack 10.

  In the power generation request blower rotation speed map shown in FIG. 18, in the region where the target stack current is relatively low (from the low load region to the medium load region), the power generation request target blower rotation number increases as the target stack current increases. Further, the power generation request target blower speed increases as the coolant temperature increases. That is, when the target stack current or the cooling water temperature increases, the load on the fuel cell stack 10 increases, and accordingly, the rotational speed of the circulation blower 45 is set to be further increased.

  In a region where the target stack current is relatively high (high load region), the power generation request target blower speed decreases as the target stack current increases. This is because, in the high load region, the output of the ejector 46 improves as the target stack current increases, so the output required for the circulation blower 45 decreases.

  The power generation request target rotation speed calculation unit B1041 outputs the calculated power generation request target rotation speed to the Max selection unit B1044.

  The target turbine inlet temperature is input to the first-order lag filter B1042. The first-order lag filter B1042 calculates the estimated turbine inlet temperature from the target turbine inlet temperature and the previous value of the turbine inlet temperature based on the above equation (1). Then, the first-order lag filter B1042 outputs the estimated turbine inlet temperature to the turbine required target rotational speed calculation unit B1043.

  Thus, as shown in FIG. 13, the target turbine inlet temperature determined from the detected values of the air flow rate and the electric motor rotation number is not used as it is, but the estimated turbine inlet temperature considering the previous value of the turbine inlet temperature is circulated. Since it is used for controlling the rotational speed of the blower 45, the circulating blower 45 is controlled to the wet side (output increasing side) before the temperature of the combustor 32 rises, and the liquid water supplied to the combustor 32 is reduced. This can increase the occurrence of misfire and the like.

  The estimated turbine inlet temperature and the target air flow rate are input to the turbine required target rotation speed calculation unit B1043. The turbine required target speed calculation unit B1043 calculates the turbine required target from the estimated turbine inlet temperature and the cooling water temperature based on a predetermined map indicating the relationship between the estimated turbine inlet temperature, the target air flow rate, and the turbine required target blower speed. Calculate the blower speed.

  The turbine required target blower rotational speed is a target value of the rotational speed of the circulation blower 45 required from the viewpoint of controlling the turbine inlet temperature to the target turbine inlet temperature. That is, the turbine required target blower rotational speed is a target value of the rotational speed of the circulation blower 45 that is determined from the viewpoint of preventing temperature rise of the combustor 32 and misfire due to liquid water.

  In particular, in the present embodiment, the turbine required target rotational speed calculation unit B1043 adjusts the flow rate of the liquid water supplied to the combustor 32, and the anode outlet 10d of the fuel cell stack 10 correlates with the flow rate of the liquid water. The turbine required target blower rotational speed is determined from the viewpoint of controlling the relative humidity RH.

  FIG. 19 shows an example of a turbine required target blower rotational speed map. As shown in the figure, in the turbine required target blower rotational speed map, in the low load region where the estimated turbine inlet temperature is equal to or less than a predetermined value T1, the turbine required target blower rotational speed is not affected regardless of the estimated turbine inlet temperature and the target air flow rate. Small change.

  This is because the temperature in the combustor 32 is relatively low in the low-load region, and the combustion flow is reduced by minimizing the supply flow rate of liquid water to the combustor 32 without increasing the rotational speed of the circulation blower 45 as much as possible. This is to prevent the thermal reaction in the vessel 32 from being hindered by vaporization of liquid water.

  On the other hand, in the high load region where the estimated turbine inlet temperature is equal to or higher than the predetermined value T1 or T2 according to the target air flow rate, the turbine required target blower rotational speed increases as the estimated turbine inlet temperature increases. This is because the rotational speed of the circulation blower 45 is increased in order to increase the relative humidity RH of the anode outlet 10d in order to increase the flow rate of the liquid water supplied to the combustor 32 as the load increases.

  In the turbine required target blower rotational speed map, the turbine required target blower rotational speed is set so as to increase as the target air flow rate increases in the high load region. Here, when the air flow rate increases, the liquid water discharged from the cathode outlet 10b of the fuel cell stack 10 becomes larger than the liquid water discharged from the anode outlet 10d.

  Therefore, in order to prevent this tendency, in the high load region, when the air flow rate increases, the rotational speed of the circulation blower 45 is increased, and the water in the fuel cell stack 10 is guided to the anode side in the fuel cell stack 10. Like to do. Thereby, when the air flow rate increases, the relative humidity RH of the anode outlet 10d can be further increased.

  That is, in the present embodiment, the relative humidity of the anode outlet 10d is increased by increasing the ratio of the rotation speed (circulation hydrogen flow rate) of the circulation blower 45 in the hydrogen circulation passage 43 to the air flow rate supplied to the fuel cell stack 10. As a result, the flow rate of liquid water supplied to the combustor 32 can be increased.

  Returning to FIG. 18, the turbine required target rotational speed calculation unit B1043 outputs the turbine required target blower rotational speed to the maximum selection unit B1044.

  The power generation request target blower rotation speed and the turbine request target blower rotation speed are input to the maximum selection unit B1044. The maximum selector B1044 calculates the larger one of the power generation request target blower rotation speed and the turbine request target blower rotation speed as the target blower rotation speed.

  Then, returning to FIG. 10, the circulation blower control unit B104 controls the output of the circulation blower 45 so that the rotation speed of the circulation blower 45 approaches the target blower rotation speed.

  The purge valve controller B105 receives the coolant temperature and the target stack current. The purge valve control unit B105 controls the duty ratio of the purge valve based on the detected coolant temperature value and the target stack current.

  FIG. 20 is a diagram illustrating the function of the purge valve control unit B105.

  As shown in the figure, the purge valve control unit B105 purges from the target stack current and the cooling water temperature based on the purge valve duty ratio map indicating the relationship between the detected coolant temperature value, the target stack current, and the duty ratio of the purge valve. The target purge valve duty ratio of the valve 52 is calculated. Here, the target purge valve duty ratio is a target value of the duty ratio of the purge valve 52 determined from the viewpoint of suitably adjusting the flow rate of the liquid water supplied to the combustor 32 through the purge passage 51.

  Referring to the purge valve duty ratio map shown in the figure, the target stack current increases in a region (high load region) where the target stack current is equal to or greater than a predetermined value (I1, I2, I3 in FIG. 20) according to the coolant temperature. The target purge valve duty ratio increases as the operation is performed. This is because when the target stack current is large, the load of the fuel cell stack 10 is high, and water generated by power generation increases, so that the duty ratio of the purge valve 52 is controlled to increase in order to discharge through this moisture. Because. In the present embodiment, the target stack current values I1, I2, and I3 on the horizontal axis that are different for each coolant temperature indicated by the dotted line in the map shown in FIG. 20 correspond to “predetermined values”.

  In addition, the target purge valve duty ratio increases as the coolant temperature detection value increases in a region where the target stack current is relatively large. When the detected value of the cooling water temperature is relatively high, the temperature in the hydrogen circulation passage 43 is relatively high, so the amount of saturated water vapor in the gas in the hydrogen circulation passage 43 increases and more water vapor circulates in the hydrogen. It will be contained in the gas in the passage 43. Therefore, the duty ratio of the purge valve 52 is set in the increasing direction so as not to decrease the hydrogen concentration in the hydrogen circulation passage 43.

  On the other hand, also in the middle load region, the target purge valve duty ratio increases as the coolant temperature detection value increases. This is to maintain the hydrogen concentration in the hydrogen circulation passage 43 at a certain level or more from the viewpoint of maintaining the power generation performance of the fuel cell stack 10.

  Then, the purge valve control unit B105 controls the purge valve 52 so that the duty ratio of the purge valve 52 approaches the calculated target purge valve duty ratio.

  Returning to FIG. 10, the target air flow rate and the target turbine inlet temperature are input to the combustor hydrogen amount control unit B106. The combustor hydrogen amount control unit B106 controls the opening degree of the combustor hydrogen amount adjustment valve 49 based on the target air flow rate and the target turbine inlet temperature.

  For example, the combustor hydrogen amount control unit B106 determines a target turbine inlet temperature and a target turbine inlet temperature based on a map that defines a relationship between a predetermined target turbine inlet temperature, a target air flow rate, and an opening degree of the combustor hydrogen amount control valve 49. The target opening of the combustor hydrogen amount adjusting valve 49 is calculated from the target air flow rate. The combustor hydrogen amount control unit B106 performs feedback control of the combustor hydrogen amount adjustment valve 49 so that the opening degree of the combustor hydrogen amount adjustment valve 49 approaches the target opening degree.

  According to the fuel cell system 100 and the control method of the fuel cell system 100 according to the embodiment of the present invention described above, the following operational effects are obtained.

  The fuel cell system 100 according to the present embodiment includes a fuel supply device (anode supply mechanism 14) for supplying hydrogen as fuel to an anode inlet 10c as an anode electrode of a fuel cell stack 10 as a fuel cell, and a fuel cell stack 10 An oxidant supply device (cathode supply / discharge mechanism 12) for supplying air as an oxidant to the cathode inlet 10a as a cathode electrode, and an HFR measurement device 18 as an operation state detection unit for detecting the operation state of the fuel cell stack 10, The air flow meter 26, the air pressure sensor 28, the circulating hydrogen pressure sensor 47, the combustor supply hydrogen pressure detection sensor 50, the motor rotation speed sensor 72, the water temperature sensor 82, the current sensor 91, and the voltage sensor 92, and the operation state detection unit The operation control device that controls the fuel supply device and the oxidant supply device according to the signal It includes a controller 20, a.

  Further, the fuel cell system 100 includes a liquid water supply unit (a purge passage 51 and a purge valve 52) that supplies liquid water discharged from the fuel cell stack 10 to the combustor 32. The oxidant supply device includes a compressor 64 that supplies air to the cathode inlet 10a of the fuel cell stack 10, a turbine 62 that drives the compressor 64, and a combustor 32 that generates combustion gas that drives the turbine 62. .

  Then, the controller 20 uses the load (target stack current) of the fuel cell stack 10, the target compressor power as the target power of the compressor 64, the target turbine recovery power that is the target recovery power of the turbine 62, and the target inlet temperature of the turbine 62. Based on a liquid water flow rate control parameter including a certain target turbine inlet temperature, a liquid water flow rate control unit (circulation blower control unit B104 and A purge valve control unit B105).

Here, the liquid water supplied to the combustor 32 is vaporized by heat generated by the combustion of hydrogen and air in the combustor 32 and converted into water vapor. This water vapor is supplied to the turbine 62 and contributes to the recovery power of the turbine 62. Therefore, by controlling the liquid water flow rate supplied to the combustor 32 according to the liquid water flow rate control parameter,
The amount of liquid water supplied to the combustor 32 can be suitably controlled according to the load state of the fuel cell stack 10 correlated with the liquid water flow rate control parameter. Thereby, turbine efficiency can be improved.

  In particular, since the turbine 62 is driven by steam obtained by vaporizing liquid water, the temperature of the gas supplied to the turbine 62 can be lowered, and desired power can be recovered while suppressing the influence of heat on system components. can do.

  Furthermore, in obtaining the recovery power of the turbine 62 in this way, the required power can be obtained at a lower temperature than in the case where liquid water is not added, so that generation of nitrogen oxides and catalyst in the combustor 32 are achieved. Deterioration can also be suppressed.

  In the present embodiment, an electric motor 60 that drives the compressor 64 independently from the turbine 62 is further provided. More specifically, the fuel cell system 100 of the present embodiment drives the compressor 64 with the recovery power from the turbine 62 and the power generated by the electric motor 60.

  Therefore, by using the liquid water discharged from the fuel cell stack 10 in such a system in the combustor 32, the turbine recovery power can be increased as described above, so the power consumption of the electric motor 60 is reduced. Therefore, the size of the fuel cell stack 10 can be reduced.

  In the fuel cell system 100 of the present embodiment, the purge passage 51 and the purge valve 52 as the liquid water supply unit supply liquid water from the anode outlet 10d of the fuel cell stack 10 to the combustor 32 (see FIG. 1). ).

  Thereby, the flow rate of the liquid water discharged from the anode outlet 10d can be suitably controlled, and the flow rate of the liquid water supplied to the combustor 32 can be suitably adjusted.

  In the fuel cell system 100 of the present embodiment, the liquid water supply unit includes a purge passage 51 as a liquid water supply passage for discharging liquid water from the anode outlet 10d of the fuel cell stack 10 to the combustor 32, and a purge passage. And a purge valve 52 as a liquid water supply amount adjusting valve provided in 51. Then, the purge valve control unit B105 as the liquid water amount control unit controls the flow rate of the liquid water by adjusting the duty ratio of the purge valve 52 which is the valve opening time ratio of the purge valve 52 (see FIG. 20).

  Thereby, control of the supply flow rate of the liquid water to the combustor 32 can be realized by a simple method of adjusting the duty ratio of the purge valve 52. In particular, when a large amount of liquid water is required to be supplied to the combustor 32 such as when the load on the fuel cell stack 10 is large, it can be dealt with by increasing the duty ratio of the purge valve 52.

  In particular, in the fuel cell system 100 of the present embodiment, the liquid water supply passage is a purge passage 51 through which the purge gas discharged from the anode supply mechanism 14 (hydrogen circulation passage 43) of the fuel cell stack 10 flows. The control valve is a purge valve 52 provided in the purge passage 51.

  Therefore, a configuration for controlling the amount of liquid water supplied to the combustor 32 can be realized by using a configuration necessary for discharging the purge gas to the outside in the anode supply mechanism 14 of the fuel cell system 100. That is, the liquid water supply amount to the combustor 32 can be controlled with a simpler configuration.

  Further, in the fuel cell system 100 according to the present embodiment, the purge valve control unit B105 supplies the combustor 32 to the combustor 32 when the target stack current as the liquid water flow rate control parameter becomes a high load region that is equal to or greater than the predetermined values I1, I2, and I3. Supply of liquid water is started (see FIG. 20). Here, “starting the supply of liquid water to the combustor 32” means that the supply is started from the viewpoint of using liquid water in the combustor 32, and the target stack current is a predetermined value. Even if it is less than the value, it is not excluded that a small amount of liquid water is supplied to the combustor 32.

  Thus, even if the temperature in the combustor 32 is relatively high and the heat of vaporization is applied to the liquid water supplied into the combustor 32, the load of hydrogen and oxygen in the combustor 32 is small and has little influence on the combustion reaction. A region can be selected to supply liquid water to the combustor 32. Therefore, the energy of the water vapor evaporated from the liquid water can be given to the turbine 62 while suppressing misfire in the combustor 32.

  Furthermore, in the present embodiment, the purge valve control unit B105 performs the combustion as the target stack current is equal to or greater than the predetermined values I1, I2, and I3 and the command electric motor torque, the target turbine recovery power, and the target turbine inlet temperature increase. The vessel supply liquid water flow rate is increased (see FIG. 20).

  Thereby, in the high load region, the flow rate of the water vapor supplied to the turbine 62 is increased by increasing the flow rate of the liquid water supplied to the combustor 32 as the load increases. Therefore, the energy of the steam supplied to the turbine 62 can be increased in accordance with the increase in load. Thereby, the recovery power by the turbine 62 can be increased in the high load region, and the assist force of the compressor 64 by the recovery power of the turbine 62 can be increased. Therefore, this contributes to a reduction in power consumption of the electric motor 60 that drives the compressor 64. As a result, it is possible to reduce the output request (required generated power) to the fuel cell stack 10, and the size of the fuel cell stack 10 can be reduced. Miniaturization can be achieved.

  Further, in the fuel cell system 100 of the present embodiment, the purge valve control unit B105 controls the flow rate of the liquid water by adjusting the relative humidity RH of the anode outlet 10d of the fuel cell stack 10 (see FIG. 12).

  Thereby, the flow volume of the liquid water supplied to the combustor 32 can be suitably increased / decreased by adjusting the relative humidity RH of the anode outlet 10d.

  In particular, the flow rate of liquid water supplied to the combustor 32 can be increased by increasing the relative humidity RH of the anode outlet 10d, while the relative humidity RH of the anode outlet 10d is decreased to the combustor 32. The flow rate of the supplied liquid water can be reduced.

  In the fuel cell system 100 of the present embodiment, the wetting control unit B102 as the liquid water amount control unit adjusts the cooling water temperature of the fuel cell stack 10 (adjustment of the radiator fan rotation speed and the three-way valve opening degree). The relative humidity RH of the anode outlet 10d is controlled (see FIG. 12).

  Thereby, the relative humidity RH of the anode outlet 10d can be adjusted by a simple method of adjusting the cooling water temperature of the fuel cell stack 10, and as a result, the flow rate of the liquid water supplied to the combustor 32 can be adjusted.

  In particular, in the present embodiment, in the high load region, the target HFR decreases to wet the electrolyte membrane of the fuel cell stack 10 more (see target HFR calculation unit B1021 in FIG. 12). Here, by performing the operation of decreasing the cooling water temperature, the water content (saturated water vapor amount) of the air in the cathode electrode in the fuel cell stack 10 is decreased while the water content in the fuel cell stack is increased. The amount of water discharged from the cathode outlet 10b of the fuel cell stack 10 is reduced.

  On the other hand, although the amount of moisture discharged from the cathode outlet 10b of the fuel cell stack 10 is thus reduced, the amount of moisture in the fuel cell stack itself is increasing. The water discharged from the anode outlet 10d of the fuel cell stack 10 increases, and the relative humidity RH at the anode outlet 10d of the fuel cell stack 10 increases. As a result, the supply flow rate of liquid water to the combustor 32 can be increased. In addition, when decreasing the supply flow rate of the liquid water to the combustor 32, an operation for increasing the cooling water temperature is performed.

  Furthermore, in the fuel cell system 100 of the present embodiment, the wetness control unit B102 as the liquid water amount control unit adjusts the air flow rate (wet control request target air flow rate) supplied to the fuel cell stack 10 to adjust the anode outlet 10d. The relative humidity RH is controlled (see FIG. 12).

  Thereby, the relative humidity RH of the anode outlet 10d is adjusted by a simple method of adjusting the flow rate of air supplied to the fuel cell stack 10, and as a result, the flow rate of liquid water supplied to the combustor 32 can be adjusted. it can.

  In particular, when the flow rate of air supplied to the cathode inlet 10a of the fuel cell stack 10 is decreased, the moisture in the fuel cell stack 10 is increased even though the moisture discharged from the cathode outlet 10b is relatively reduced. To do. Therefore, the moisture discharged from the anode outlet 10 d of the fuel cell stack 10 increases due to the increased moisture in the fuel cell stack 10. Therefore, the relative humidity RH at the anode outlet 10d increases, and the supply flow rate of liquid water to the combustor 32 can be increased.

  Further, the fuel cell system 100 of the present embodiment further includes a hydrogen circulation passage 43 as a fuel circulation passage for circulating the hydrogen supplied to the fuel cell stack 10. Then, the circulation blower control unit B104 as the liquid water flow rate control unit controls the relative humidity RH of the anode outlet 10d by adjusting the ratio of the hydrogen circulation flow rate to the air flow rate supplied to the fuel cell stack 10 (FIG. 18 turbine required target rotation speed calculation unit B1043).

  That is, by changing the ratio of the hydrogen circulation flow rate to the air flow rate supplied to the fuel cell stack 10, the water discharged from the anode outlet 10d can be adjusted, and the liquid water supplied to the combustor 32 can be adjusted. The flow rate can be adjusted.

  In particular, by increasing the ratio of the hydrogen circulation flow rate to the air flow rate supplied to the fuel cell stack 10, the moisture discharged from the anode outlet 10 d to the moisture discharged from the cathode outlet 10 b of the fuel cell stack 10 is increased. Since it can increase, the flow volume of the liquid water supplied to the combustor 32 can be increased.

  In particular, in the fuel cell system 100 of the present embodiment, the liquid water flow rate control unit includes a circulation blower control unit B104 as a fuel circulation flow rate control unit that controls the hydrogen circulation flow rate. Then, the circulation blower control unit B104 adjusts the ratio of the hydrogen circulation flow rate to the air flow rate supplied to the fuel cell stack 10 (turbine required target rotational speed calculation unit B1043 in FIG. 18).

  Thereby, even in a scene where the cooling water temperature and the air flow rate cannot be changed, the wet state of the electrolyte membrane in the fuel cell stack 10 is controlled by controlling the hydrogen circulation flow rate, and the liquid water flow rate discharged from the anode outlet 10d is reduced. Can be controlled. That is, even in such a scene, the flow rate of liquid water supplied to the combustor 32 can be suitably controlled.

  The hydrogen circulation flow rate may be controlled based on at least one of the number of stages of the ejector 46 and the diameter of the ejector nozzle, instead of or together with the rotational speed of the circulation blower 45. For example, as the hydrogen circulation flow rate required for the generated current is higher, the number of stages of the ejector 46 may be reduced, or the diameter of the ejector nozzle may be reduced.

  In the fuel cell system 100, the circulation blower control unit B104 as the liquid water flow rate control unit controls the flow rate of the combustor supply liquid water when the estimated turbine inlet temperature, which is regarded as the temperature of the combustor 32, exceeds a predetermined value. Start (see FIG. 19). Here, “starting the supply of liquid water to the combustor 32” means starting supply from the viewpoint of using liquid water in the combustor 32, and the estimated turbine inlet temperature is Even if it is less than the predetermined value, it is not excluded that a small amount of liquid water is supplied to the combustor 32.

  Accordingly, when the estimated turbine inlet temperature becomes equal to or higher than a predetermined value, the control of the liquid water supply flow rate to the combustor 32 is started. Water will be supplied. Therefore, it is possible to prevent the combustion reaction of hydrogen and oxygen from being hindered by supplying liquid water with the temperature of the combustor 32 being low.

  Further, in the fuel cell system 100 of the present embodiment, the purge passage 51 as the liquid water supply unit has a liquid water supply port 51 a inside the combustor 32. And this liquid water supply port 51a is arrange | positioned above the highest temperature point T inside the combustor 32 (refer FIG. 3).

  As a result, the liquid water discharged from the purge passage 51 is supplied to the position of the maximum temperature point T inside the combustor 32 while dropping due to the influence of gravity. The uneven distribution can be reduced and the maximum temperature can be lowered. Thereby, generation | occurrence | production of a nitrogen oxide and partial catalyst deterioration inside the combustor 32 can be prevented, without reducing turbine recovery power.

  Further, in the fuel cell system 100 of the present embodiment, the purge passage 51 as a liquid water supply unit has a liquid water supply port 51 a inside the combustor 32. And this liquid water supply port 51a is arrange | positioned downstream of the gas flow direction (arrow A direction of FIG. 3) with respect to the hydrogen supply port 48a as a fuel supply port which supplies hydrogen inside the combustor 32. FIG. .

  As a result, the liquid water is supplied to the portion where the hydrogen concentration is relatively high and the combustion temperature tends to be high due to the hydrogen supplied from the hydrogen supply port 48a, so that heat can be efficiently applied to the liquid water. The liquid water can be quickly vaporized and converted into water vapor and supplied to the turbine 62. Moreover, by supplying liquid water to a relatively low temperature portion in the combustor 32, it is possible to suppress the combustion of the combustor 32 with the heat of vaporization of the liquid water and reduce the combustion efficiency.

  As described above, in this embodiment, the control method of the fuel cell system 100 in which the compressor 64 that supplies the air as the oxidant to the cathode electrode (cathode inlet 10a) of the fuel cell stack 10 as the fuel cell is driven by the turbine 62. Is provided. In this control method, the load (target stack current) of the fuel cell stack 10, the target compressor power as the target power of the compressor 64, the target turbine recovery power that is the target recovery power of the turbine 62, and the target inlet temperature of the turbine 62 The liquid water flow rate control parameter including the target turbine inlet temperature is acquired, and the flow rate of the liquid water supplied to the combustor 32 that generates the combustion gas supplied to the turbine 62 is controlled based on the liquid water flow rate control parameter. .

  Thus, by controlling the liquid water flow rate supplied to the combustor 32 according to the liquid water flow rate control parameter, the combustion is performed according to the load state of the fuel cell stack 10 correlated with the liquid water flow rate control parameter. The amount of liquid water supplied to the vessel 32 can be suitably controlled. Thereby, turbine efficiency can be improved.

  In the control of the embodiment described above, the combustor hydrogen amount control unit B106 determines whether the target turbine inlet temperature is equal to or higher than a predetermined value. If the target turbine inlet temperature is lower than the predetermined value, the combustor It is preferable that the hydrogen amount adjusting valve 49 is fully closed and the combustor hydrogen amount adjusting valve 49 starts to be opened when the target turbine inlet temperature is equal to or higher than a predetermined value.

  That is, the combustor hydrogen amount control unit B106 is preferably configured to start supplying liquid water to the combustor 32 when the target turbine inlet temperature becomes a predetermined value or more. As a result, since the supply of liquid water to the combustor 32 is started after the temperature in the combustor 32 becomes sufficiently high, the temperature in the combustor 32 is increased by the heat of vaporization of the liquid water. It is possible to further suppress the reduction to an extent that hinders the combustion reaction of oxygen. As a result, the energy of water vapor evaporated from the liquid water can be applied to the turbine 62 while suppressing misfires in the combustor 32.

(Second Embodiment)
Hereinafter, a second embodiment will be described. In addition, the same code | symbol is attached | subjected to the element similar to 1st Embodiment, and the description is abbreviate | omitted. In particular, in this embodiment, the start timing of the supply of liquid water to the combustor 32 is determined based on the detected value of the combustion exhaust gas temperature.

  FIG. 21 is a schematic configuration diagram of the fuel cell system 100 of the present embodiment.

  As illustrated, in this embodiment, a combustor temperature sensor 94 is provided downstream of the combustor 32 in the cathode gas discharge passage 24. The combustor temperature sensor 94 detects the temperature of the combustion exhaust gas discharged from the combustor 32. The combustor temperature sensor 94 outputs a combustion exhaust gas temperature detection value signal to the controller 20.

  FIG. 22 is a block diagram showing the overall functions of the controller 20 of this embodiment.

  As illustrated, in the present embodiment, instead of the configuration in which the previous value of the target turbine inlet temperature in FIG. 10 in the first embodiment is input to the air system FB control unit B103, the combustion exhaust gas temperature detection value is the air system FB control unit. Input to B103.

  Further, the combustion exhaust gas temperature detection value is input to the circulation blower control unit B104 instead of the target turbine inlet temperature.

  FIG. 23 is a block diagram illustrating detailed functions of the air system control unit B 1034 according to the present embodiment.

  As illustrated, in the present embodiment, the detected air flow rate value, the detected air pressure value, and the detected exhaust gas temperature value are input to the turbine recovery power estimation unit B201.

The turbine recovery power estimation unit B201 calculates the estimated turbine recovery power from the air flow rate detection value, the air pressure detection value, and the combustion exhaust gas temperature detection value using the equation (2) described in the first embodiment. That is, the estimated turbine recovery power is calculated using the formula (2) in place of the “estimated turbine inlet temperature T _{t_in_e} ” in the first embodiment instead of the detected value of the combustion exhaust gas temperature.

  FIG. 24 is a block diagram illustrating functions of the circulation blower control unit B104 according to the present embodiment.

  As illustrated, in the present embodiment, the first-order lag filter B1042 of the circulation blower control unit B104 in the first embodiment is not provided, and the detected value of the combustion exhaust gas temperature is input to the turbine required target rotation speed calculation unit B1043.

  Therefore, the turbine required target rotational speed calculation unit B1043 calculates the turbine required target blower rotational speed based on the detected value of the combustion exhaust gas temperature and the target air flow rate. That is, the circulation blower control unit B104 controls the rotation speed of the circulation blower based on the detected value of the combustion exhaust gas temperature.

  In particular, as can be seen from the map of the turbine required target rotational speed calculation unit B1043 in FIG. 24, the turbine required target blower rotational speed starts to increase in a region where the detected value of the combustion exhaust gas temperature exceeds a predetermined value, and the liquid to the combustor 32 The supply of water will be started. Therefore, in the present embodiment, when the combustion exhaust gas temperature detection value by the combustor temperature sensor 94 becomes a predetermined value or more, the supply of liquid water to the combustor 32 is substantially started.

  The fuel cell system 100 according to the embodiment of the present invention described above has the following operational effects.

  The fuel cell system 100 according to the present embodiment includes a combustor temperature sensor 94 as a temperature sensor that detects the temperature of the combustor 32, and the circulation blower control unit B 104 as a liquid water flow rate control unit is a combustor temperature sensor 94. When the detected flue gas temperature detected value as the detected value is equal to or higher than a predetermined value, control of the combustor supply liquid water flow rate is started (turbine required target rotational speed calculation unit B1043 in FIG. 24).

  Thereby, the timing of starting the supply of liquid water to the combustor 32, that is, the timing of increasing the rotational speed of the circulation blower 45 can be more suitably determined based on the actual detected value of the exhaust gas temperature.

  For example, when the purge valve control unit B105 relatively lowers the duty ratio of the purge valve 52 when the detected value of the combustion exhaust gas temperature is less than a predetermined value, and the detected value of the combustion exhaust gas temperature becomes equal to or higher than the predetermined value. Control of the combustor supply liquid water flow rate may be started by starting to increase the purge valve 52.

(Third embodiment)
Hereinafter, the third embodiment will be described. In addition, the same code | symbol is attached | subjected to the element similar to 1st Embodiment, and the description is abbreviate | omitted. In particular, in this embodiment, the start timing of liquid water supply to the combustor 32 is determined based on the hydrogen supply time to the combustor 32.

  In the present embodiment, the combustor hydrogen amount adjustment valve 49 is configured as a valve that can be switched on and off, such as an intermittent drive injector.

  FIG. 25 is a block diagram showing the overall functions of the controller 20 of the present embodiment.

  As illustrated, the controller 20 includes a hydrogen supply valve opening time calculation unit B107 in place of the configuration in which the previous target turbine inlet temperature in FIG. 10 in the first embodiment is input to the air system FB control unit B103. Yes.

  Opening state information is input from the combustor hydrogen amount adjustment valve 49 to the hydrogen supply valve opening time calculation unit B107. The valve opening state information is information indicating whether the combustor hydrogen amount adjustment valve 49 is in an on state (open state) or an off state (closed state).

  The hydrogen supply valve opening time calculation unit B107 calculates the duty ratio (valve opening time ratio) of the combustor hydrogen amount adjustment valve 49 based on the valve opening state information. Specifically, the hydrogen supply valve opening time calculation unit B107 calculates the total time (valve opening time) when the combustor hydrogen amount adjustment valve 49 is in the ON state during a predetermined time period, and calculates the total time as time. The value divided by the period is set as the duty ratio of the combustor hydrogen amount adjustment valve 49. Therefore, this duty ratio substantially corresponds to the time during which hydrogen is supplied from the high-pressure tank 40 to the combustor 32 (hydrogen supply time).

  The hydrogen supply valve opening time calculation unit B107 outputs the calculated duty ratio of the combustor hydrogen amount adjustment valve 49 to the air system FB control unit B103 and the circulation blower control unit B104.

  That is, the duty ratio of the combustor hydrogen amount adjustment valve 49 is input to the circulation blower control unit B104 instead of the target turbine inlet temperature.

  FIG. 26 is a block diagram illustrating detailed functions of the air system control unit B 1034 according to the present embodiment.

  As illustrated, in this embodiment, the duty ratio of the combustor hydrogen amount adjustment valve 49 calculated by the hydrogen supply valve opening time calculation unit B107 is input to the turbine recovery power estimation unit B201.

  The turbine recovery power estimation unit B201 calculates the estimated turbine recovery power based on the duty ratio of the combustor hydrogen amount adjustment valve 49. Specifically, the turbine recovery power estimation unit B201 calculates from the duty ratio of the combustor hydrogen amount adjustment valve 49 based on a predetermined map or the like indicating the relationship between the duty ratio of the combustor hydrogen amount adjustment valve 49 and the estimated turbine recovery power. Calculate the estimated turbine recovery power. This map is set so that the estimated turbine recovery power increases as the duty ratio of the combustor hydrogen amount adjustment valve 49 increases.

  FIG. 27 is a block diagram illustrating functions of the circulation blower control unit B104 of the present embodiment.

  As illustrated, in the present embodiment, the primary delay filter B1042 in the circulation blower control unit B104 in the first embodiment is not provided, and the duty ratio of the combustor hydrogen amount adjustment valve 49 is input to the turbine required target rotation speed calculation unit B1043. doing.

  Therefore, the turbine required target rotational speed calculation unit B1043 calculates the turbine required target blower rotational speed based on the duty ratio of the combustor hydrogen amount adjusting valve 49 and the target air flow rate. That is, the circulation blower control unit B104 controls the rotation speed of the circulation blower based on the duty ratio of the combustor hydrogen amount adjustment valve 49.

  In particular, in the region where the duty ratio of the combustor hydrogen amount adjusting valve 49 is equal to or greater than a predetermined value, the turbine required target blower rotation speed starts increasing, and the supply of liquid water to the combustor 32 is started in earnest. Therefore, in the present embodiment, when the duty ratio of the combustor hydrogen amount adjustment valve 49 corresponding to the hydrogen supply time to the combustor 32 becomes a predetermined value or more, the supply of liquid water to the combustor 32 is substantially started. The Rukoto.

  The fuel cell system 100 according to the embodiment of the present invention described above has the following operational effects.

  When the fuel supply time (duty ratio of the combustor hydrogen amount adjustment valve 49), which is the supply time of hydrogen as fuel to the combustor 32, becomes higher than a predetermined value, the circulation blower control unit B104 as the liquid water flow rate control unit Control of the combustor supply liquid water flow rate is started (turbine required target rotational speed calculation unit B1043 in FIG. 27).

  Thereby, based on the duty ratio of the combustor hydrogen amount adjustment valve 49, the timing for starting the supply of liquid water to the combustor 32, that is, the timing for increasing the rotational speed of the circulation blower 45 can be determined more suitably.

  For example, when the duty ratio of the combustor hydrogen amount adjustment valve 49 is less than a predetermined value, the purge valve control unit B105 relatively lowers the duty ratio of the purge valve 52 and sets the duty ratio of the combustor hydrogen amount adjustment valve 49. The control of the combustor supply liquid water flow rate may be started by starting the increase of the purge valve 52 when the ratio becomes a predetermined value or more.

(Fourth embodiment)
The fourth embodiment will be described below. In addition, the same code | symbol is attached | subjected to the element similar to 1st Embodiment, and the description is abbreviate | omitted. In the present embodiment, the start timing of the supply of liquid water to the combustor 32 is determined based on the opening degree of the combustor hydrogen amount adjustment valve 49.

  In this embodiment, as the combustor hydrogen amount adjustment valve 49, a valve whose opening degree can be adjusted, such as a proportional solenoid, is used.

  FIG. 28 is a schematic configuration diagram of the fuel cell system 100 of the present embodiment.

  As shown in the figure, in this embodiment, the combustor hydrogen amount adjusting valve 49 is provided with an opening degree sensor 49a for detecting the opening degree thereof. The opening sensor 49 a outputs a signal of a detected value of the opening of the combustor hydrogen amount adjustment valve 49 to the controller 20.

  FIG. 29 is a block diagram showing the overall functions of the controller 20 of the present embodiment.

  As shown in the figure, in this embodiment, the detected value of the opening degree of the combustor hydrogen amount adjusting valve 49 detected by the opening degree sensor 49a is sent to the air system FB control unit B103 and the circulation blower control unit B104 (hereinafter, “ (Also referred to as “combustor hydrogen supply valve opening detection value”).

  FIG. 30 is a block diagram illustrating detailed functions of the air system control unit B 1034 according to the present embodiment.

  As illustrated, in this embodiment, the detected value of the combustor hydrogen supply valve opening is input to the turbine recovery power estimation unit B201.

  The turbine recovery power estimation unit B201 calculates an estimated turbine recovery power based on the detected value of the combustor hydrogen supply valve opening. Specifically, the turbine recovery power estimation unit B201 calculates the estimated turbine from the combustor hydrogen supply valve opening detection value based on a predetermined map indicating the relationship between the combustor hydrogen supply valve opening detection value and the estimated turbine recovery power. The recovery power is calculated.

  FIG. 31 is a block diagram illustrating functions of the circulation blower control unit B104 of the present embodiment.

  As illustrated, in this embodiment, the primary lag filter B1042 of the circulation blower control unit B104 in the first embodiment is not provided, and the detected value of the combustor hydrogen supply valve opening is input to the turbine required target rotation speed calculation unit B1043. ing.

  Therefore, the turbine required target rotational speed calculation unit B1043 calculates the turbine required target blower rotational speed based on the detected value of the combustor hydrogen supply valve opening and the target air flow rate. That is, the circulation blower control unit B104 controls the rotation speed of the circulation blower based on the detected value of the combustor hydrogen supply valve opening.

  In particular, in the region where the detected value of the combustor hydrogen supply valve opening is greater than or equal to a predetermined value, the turbine required target blower rotational speed starts increasing, and the supply of liquid water to the combustor 32 is started. Therefore, in this embodiment, when the detected value of the combustor hydrogen supply valve opening corresponding to the amount of fuel supplied to the combustor 32 becomes a predetermined value or more, the supply of liquid water to the combustor 32 is substantially started. It will be.

  The fuel cell system 100 according to the embodiment of the present invention described above has the following operational effects.

  The fuel cell system 100 according to the present embodiment includes a combustor hydrogen amount adjusting valve 49 that adjusts the amount of fuel supplied to the combustor 32. Then, the circulation blower control unit B104 as the liquid water flow rate control unit, when the opening degree of the combustor hydrogen amount adjustment valve 49 (combustor hydrogen supply valve opening degree detection value) is equal to or greater than a predetermined value, Is started (turbine required target rotational speed calculation unit B1043 in FIG. 31).

  Thereby, based on the detected value of the combustor hydrogen supply valve opening corresponding to the amount of fuel supplied to the combustor 32, the timing for starting the supply of liquid water to the combustor 32, that is, the timing for increasing the rotational speed of the circulation blower 45. Can be more suitably determined.

  In addition, instead of the combustor hydrogen supply valve opening detection value, or together with the combustor hydrogen supply valve opening detection value, the combustor supply liquid water flow rate control is based on the integrated value of the combustor hydrogen supply valve opening. May be started.

  That is, in this embodiment, the opening of the combustor hydrogen amount adjustment valve 49 that determines the timing for starting control of the combustor supply liquid water flow rate includes not only the detected value of the combustor hydrogen supply valve opening but also the integrated value thereof. May be included.

  Further, the temperature of the combustor 32 is estimated from the detected value of the combustor hydrogen supply valve opening and the integrated value thereof, and the estimated temperature of the combustor and the target air flow rate are used as a map of the turbine required target rotational speed calculation unit B1043 in FIG. Based on this, the turbine required target blower rotational speed may be calculated.

  Further, for example, when the combustor hydrogen supply valve opening degree detection value is less than a predetermined value, the purge valve control unit B105 relatively lowers the duty ratio of the purge valve 52 so that the combustor hydrogen supply valve opening degree detection value is The control of the combustor supply liquid water flow rate may be started by starting the increase of the purge valve 52 when the predetermined value or more is reached.

  The embodiment of the present invention has been described above. However, the above embodiment only shows a part of application examples of the present invention, and the technical scope of the present invention is limited to the specific configuration of the above embodiment. Absent.

  For example, in each of the above embodiments, the liquid water from the anode outlet 10d is supplied to the combustor 32, but the liquid water from the cathode outlet 10b may be supplied to the combustor 32. However, from the viewpoint of suitably controlling the liquid water flow rate to the combustor 32, it is preferable to supply liquid water from the anode outlet 10d to the combustor 32.

  Further, in each of the above embodiments, an example has been described in which purge gas mainly containing liquid water and nitrogen is supplied to the combustor 32 through the purge passage 51. However, a purge gas containing hydrogen and a predetermined concentration together with liquid water may be supplied to the combustor 32 through the purge passage 51. Thereby, the hydrogen in the anode exhaust gas can be used for combustion in the combustor 32. In particular, in this case, even if the hydrogen concentration contained in the purge gas is relatively high, the hydrogen in the purge gas can be consumed by the combustion by the combustor 32. Therefore, the hydrogen concentration of the purge gas (or the mixed gas of the purge gas and the cathode exhaust gas) when finally discharged to the outside can be reduced.

  Further, a path for supplying liquid water from the anode outlet 10d to the combustor 32 and a path for supplying anode exhaust gas may be configured separately.

  However, by supplying liquid water and anode exhaust gas from the anode outlet 10d to the combustor 32 through the same path, supply of liquid water and anode exhaust gas to the combustor 32 and control of the supply flow rate can be controlled by a single purge passage. 51 and the purge valve 52, the system configuration is simplified.

  Further, the “compressor 64” in each of the above embodiments fulfills the function of supplying air to the cathode electrode of the fuel cell stack 10 via the cathode gas supply passage 22. Therefore, if such a function can be achieved, the “compressor 64” can be appropriately used in addition to the “compressor” (compressor having an effective discharge pressure of 200 kPa or more) recognized in a general sense. It can also replace with other compressors and blowers, such as a blower.

  Furthermore, the “turbine 62” in each of the above embodiments is connected to the fuel cell stack 10 via the cathode gas discharge passage 24. More specifically, the cathode exhaust gas from the fuel cell stack 10 is burned together with hydrogen in the combustor 32 provided in the cathode gas discharge passage 24, and the generated combustion gas is supplied to the turbine 62. However, the present invention is not limited to this. For example, the turbine 62 may be configured in a separate system from the cathode gas discharge passage 24. For example, a supply system that supplies gas from an arbitrary gas supply source to the turbine 62 and a mechanism that adjusts the supply flow rate and temperature of the gas to the turbine 62 may be provided separately.

  Further, the above embodiments can be arbitrarily combined.

DESCRIPTION OF SYMBOLS 10 Fuel cell stack 10a Cathode inlet 10b Cathode outlet 10c Anode inlet 10d Anode outlet 10e Cooling water inlet 10f Cooling water outlet 12 Cathode supply / discharge mechanism 14 Anode supply mechanism 16 Turbo supercharger 17 Heating / cooling mechanism 18 HFR measuring device 20 Controller 22 Cathode gas supply passage 24 Cathode gas discharge passage 26 Air flow meter 28 Air pressure sensor 32 Combustor 32a Cathode exhaust gas inflow passage 32b Combustion exhaust gas outflow passage 34 Nozzle vane 40 High pressure tank 41 Stack hydrogen supply passage 42 Stack supply hydrogen pressure regulating valve 43 Hydrogen circulation Passage 44 Water separator 45 Circulating blower 46 Ejector 47 Circulating hydrogen pressure sensor 48 Hydrogen supply passage for combustor 48a Hydrogen supply port 49 Combustor hydrogen amount control valve 50 Combustor supply hydrogen pressure Output sensor 51 Purge passage 51a Liquid water supply port 52 Purge valve 60 Electric motor 62 Turbine 64 Compressor 66 Rotation drive shaft 72 Motor rotation speed sensor 80 Cooling water circulation passage 82 Water temperature sensor 84 Cooling water circulation pump 86 Radiator 87 Radiator fan 88 Three-way valve 91 Current sensor 92 Voltage sensor 94 Combustor temperature sensor 100 Fuel cell system

Claims (19)

A fuel supply device for supplying fuel to the anode electrode of the fuel cell;
An oxidant supply device for supplying an oxidant to the cathode of the fuel cell;
An operation state detection unit for detecting an operation state of the fuel cell;
An operation control device that controls the fuel supply device and the oxidant supply device according to a signal from the operation state detection unit, and a fuel cell system comprising:
A liquid water supply unit that supplies liquid water discharged from the fuel cell to the combustor;
The oxidant supply device includes:
A compressor that supplies an oxidant to the cathode of the fuel cell, a turbine that drives the compressor, and a combustor that generates combustion gas that drives the turbine,
The operation control device includes:
Supply to the combustor based on a liquid water flow rate control parameter including at least one of the load of the fuel cell, the target power of the compressor, the target recovery power of the turbine, and the target inlet temperature of the turbine A liquid water flow rate control unit for controlling the flow rate of the combustor supply liquid water,
Fuel cell system. The fuel cell system according to claim 1,
An electric motor that drives the compressor independently of the turbine;
Fuel cell system. The fuel cell system according to claim 1 or 2,
The liquid water supply unit supplies liquid water from an anode outlet of the fuel cell to the combustor.
Fuel cell system. The fuel cell system according to claim 3,
The liquid water supply unit includes a liquid water supply passage for discharging liquid water from the anode outlet of the fuel cell to the combustor, and a liquid water supply amount adjustment valve provided in the liquid water supply passage. ,
The liquid water flow rate controller controls the combustor supply liquid water flow rate by adjusting a valve opening time ratio of the liquid water supply amount adjustment valve;
Fuel cell system. The fuel cell system according to claim 4, wherein
The liquid water supply passage is a purge passage through which purge gas discharged from the anode supply mechanism of the fuel cell flows.
The liquid water supply amount adjustment valve is a purge valve provided in the purge passage.
Fuel cell system. The fuel cell system according to any one of claims 1 to 5,
The liquid water flow rate control unit starts supplying liquid water to the combustor when the liquid water flow rate control parameter is equal to or greater than a predetermined value.
Fuel cell system. The fuel cell system according to claim 6,
The liquid water flow rate control unit increases the combustor supply liquid water flow rate as the liquid water flow rate control parameter increases when the liquid water flow rate control parameter is equal to or greater than the predetermined value.
Fuel cell system. The fuel cell system according to any one of claims 1 to 7,
The liquid water flow rate controller controls the combustor supply liquid water flow rate by adjusting the relative humidity at the anode outlet of the fuel cell.
Fuel cell system. The fuel cell system according to claim 8, wherein
The liquid water flow rate controller adjusts the relative humidity of the anode outlet by adjusting the temperature of cooling water for cooling the fuel cell.
Fuel cell system. The fuel cell system according to claim 8 or 9, wherein
The liquid water flow rate controller adjusts the relative humidity of the anode outlet by adjusting the flow rate of air supplied to the fuel cell;
Fuel cell system. It is a fuel cell system given in any 1 paragraph of Claims 8-10,
A fuel circulation passage for circulating fuel supplied to the fuel cell;
The liquid water flow rate controller controls the relative humidity of the anode outlet by adjusting the ratio of the circulating flow rate of fuel to the air flow rate supplied to the fuel cell;
Fuel cell system. The fuel cell system according to claim 11, wherein
The liquid water flow rate control unit is
Adjusting the ratio of the fuel circulation flow rate to the air flow rate supplied to the fuel cell based on at least one of the rotation speed of the circulation blower, the number of ejector stages, and the diameter of the ejector nozzle;
Fuel cell system. The fuel cell system according to any one of claims 1 to 12,
The liquid water flow rate control unit starts controlling the combustor supply liquid water flow rate when the temperature of the combustor becomes a predetermined value or more.
Fuel cell system. The fuel cell system according to claim 13, wherein
A temperature sensor for detecting the temperature of the combustor;
The liquid water flow rate control unit starts controlling the combustor supply liquid water flow rate when a detection value detected by the temperature sensor is equal to or greater than a predetermined value.
Fuel cell system. The fuel cell system according to claim 13 or 14,
The liquid water flow rate control unit starts control of the combustor supply liquid water flow rate when a fuel supply time, which is a fuel supply time to the combustor, is equal to or greater than a predetermined value.
Fuel cell system. The fuel cell system according to any one of claims 13 to 15, wherein
A combustor hydrogen amount control valve for adjusting the amount of fuel supplied to the combustor;
The liquid water flow rate control unit starts control of the combustor supply liquid water flow rate when the opening of the combustor hydrogen amount adjustment valve is equal to or greater than a predetermined value.
Fuel cell system. The fuel cell system according to any one of claims 1 to 16,
The liquid water supply unit has a liquid water supply port inside the combustor,
The liquid water supply port is disposed above a maximum temperature point inside the combustor.
Fuel cell system. The fuel cell system according to any one of claims 1 to 17,
The liquid water supply unit has a liquid water supply port inside the combustor,
The liquid water supply port is disposed downstream in the gas flow direction with respect to a fuel supply port that supplies fuel into the combustor.
Fuel cell system. A control method of a fuel cell system in which a compressor for supplying an oxidant to a cathode electrode of a fuel cell is driven by a turbine,
Obtaining a liquid water flow rate control parameter including at least one of a load of the fuel cell, a target power of the compressor, a target recovery power of the turbine, and a target inlet temperature of the turbine;
Based on the liquid water flow rate control parameter, the flow rate of liquid water supplied to a combustor that generates combustion gas to be supplied to the turbine is controlled.
Control method of fuel cell system.

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