JP2018098121A - Fuel battery system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fuel battery system that is able to generate power so as to suitably satisfy an acceleration request of a driver.SOLUTION: A fuel battery system 1 comprises: a valve system 4 that causes oxide gas compressed by a compressor 3 to separately flow in a fuel battery 2 and a bypass passage 7 and adjusts an amount of oxide gas to be supplied; a determining section 51 for a control device 5, which determines an amount of oxide gas to be supplied to the fuel battery 2 on the basis of power Prf required to generate power for the fuel battery 2; and a control section 52 for the control device 5 that controls the compressor 3 and the valve system 4 such that the amount of oxide gas, determined by the determining section 51 is supplied to the fuel battery 2. In a case where the power Prf required to generate power for the fuel battery 2 is smaller than a predetermined value, the control section 52 maintains the number of revolutions of the compressor 3 at a predetermined fixed value or more and, using the valve system 4, controls an amount of oxide gas to be supplied to the fuel battery 2.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a fuel cell system mounted on a fuel cell vehicle.

  In a fuel cell vehicle, power is generated by generating fuel by supplying fuel gas and oxidizing gas to the fuel cell. Since excessive supply of oxidizing gas leads to deterioration of the fuel cell, and insufficient supply leads to insufficient power of the vehicle, the amount of gas supplied from the compressor is controlled according to the request from the user (vehicle driver). For example, in Patent Document 1, the amount of oxidizing gas that needs to be supplied from the compressor to the fuel cell is determined so that the fuel cell generates power generation required power, and the compressor is supplied to supply the required oxidizing gas to the fuel cell. A method for controlling a motor is disclosed.

JP 2006-158006 A

  In the control method described in Patent Document 1, the power generation required power to the fuel cell is calculated based on information such as the accelerator depression amount of the driver of the vehicle. When the driver depresses the accelerator to request acceleration, a delay due to the inertial force occurs from when the accelerator is depressed until the compressor reaches the target rotational speed. Therefore, there is a possibility that a response satisfying the driver's acceleration request cannot be realized.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a fuel cell system capable of generating power so that the driver's acceleration request can be suitably satisfied.

  A fuel cell system according to an aspect of the present invention is a fuel cell system mounted on a fuel cell vehicle, which generates power by reacting a fuel gas and an oxidizing gas, and the oxidizing gas is supplied to the fuel cell. Compressed and supplied compressor, the fuel cell and the compressor, and the oxidizing gas compressed by the compressor is divided into the fuel cell and the bypass flow path, the fuel cell and the bypass flow A diversion unit that adjusts the supply amount of the oxidizing gas to the road, a determining unit that determines the amount of the oxidizing gas to be supplied to the fuel cell based on the power generation required power to the fuel cell, and the determination unit. A control unit that controls the compressor and the diversion unit so as to supply a sufficient amount of the oxidizing gas to the fuel cell, and the control unit generates power to the fuel cell. If determined power is less than a predetermined value, it holds the rotational speed of the compressor to a predetermined value or more, to control the supply amount of the oxidizing gas to the fuel cell by the diverter.

  According to this aspect, when the required power generation is less than a predetermined value, for example, even when the driver is not performing an acceleration operation, the compressor of the fuel cell system is not stopped, and the rotation speed of the compressor is predetermined. It holds more than the fixed value. In other words, the amount of oxidizing gas supplied to the fuel cell can be reduced without reducing the rotational speed of the compressor. For this reason, even when the driver performs a reacceleration operation, even when the power generation required power to the fuel cell increases, it is possible to quickly control the rotation speed of the compressor to a desired value, which is determined by the determination unit. An amount of oxidizing gas can be supplied to the fuel cell without delay, and as a result, power generation can be performed so that the driver's acceleration request can be suitably satisfied.

  ADVANTAGE OF THE INVENTION According to this invention, the fuel cell system which can generate electric power so that a driver | operator's acceleration request | requirement can be satisfy | filled suitably can be provided.

FIG. 1 is a block diagram showing a schematic configuration of a fuel cell system according to an embodiment. FIG. 2 is a flowchart of oxidant gas supply control performed by the fuel cell system according to the embodiment. FIG. 3 is a time chart showing the behavior of the fuel cell system and the fuel cell vehicle when the oxidizing gas supply control of FIG. 2 is performed.

  A preferred embodiment of the present invention will be described with reference to the accompanying drawings. In addition, in each figure, what attached | subjected the same code | symbol has the same or similar structure.

  The configuration of the fuel cell system 1 according to the present embodiment will be described with reference to FIG. FIG. 1 is a block diagram illustrating a schematic configuration of a fuel cell system 1 according to an embodiment. The fuel cell system 1 of this embodiment is mounted on a fuel cell vehicle 10 (vehicle). The fuel cell vehicle 10 is a vehicle that travels by generating a driving force by supplying electric power from the fuel cell 2 or a battery (not shown) to the driving motor 11.

  As shown in FIG. 1, the fuel cell system 1 includes a fuel cell 2, a compressor 3, a valve system 4 (a flow dividing unit), and a control device 5 as a part of its constituent elements.

  The fuel cell 2 generates power by reacting a fuel gas and an oxidizing gas. The fuel gas is a combustible high-pressure gas, for example, hydrogen gas. The electric power generated by the fuel cell 2 is converted into electric power by an inverter (not shown), supplied to the drive motor 11, and consumed by the drive motor 11. Further, the power generated by the fuel cell 2 can be charged into a battery mounted on the fuel cell vehicle 10. The specific configuration of the fuel cell 2 and the power generation mechanism are well-known techniques disclosed in, for example, Patent Document 1 and will not be described.

  The compressor 3 is installed on the oxidizing gas supply flow path 6 of the fuel cell 2 and compresses and supplies the oxidizing gas to the fuel cell 2. For example, the compressor 3 adjusts the air introduced into the oxidizing gas supply flow path 6 from the outside to a predetermined pressure and supplies it to the fuel cell 2 as oxidizing gas. The pressure of the oxidizing gas can be adjusted by controlling the rotation speed of the compressor 3, for example. The rotation speed of the compressor 3 is controlled by the control device 5.

  The valve system 4 is disposed between the fuel cell 2 and the compressor 3 on the oxidizing gas supply channel 6. The oxidizing gas supply channel 6 has a bypass channel 7 that bypasses the fuel cell 2 at the position of the valve system 4. The valve system 4 divides the oxidizing gas compressed by the compressor 3 into the fuel cell 2 and the bypass channel 7. The valve system 4 adjusts the supply amount of the oxidizing gas to the fuel cell 2 and the bypass channel 7 by changing the valve opening at the branching portion of the oxidizing gas supply channel 6 to the bypass channel 7. Can do. Hereinafter, the oxidizing gas supply amount to the fuel cell 2 and the bypass channel 7 in the valve system 4 is expressed as a diversion ratio R (bypass channel side flow rate / overall channel). As the diversion ratio R is closer to 0, the supply amount of the oxidizing gas to the bypass channel 7 decreases and the supply amount of the oxidizing gas to the fuel cell 2 increases. On the other hand, the closer the diversion ratio R is to 1, the more the amount of oxidizing gas supplied to the bypass channel 7 increases and the amount of oxidizing gas supplied to the fuel cell 2 decreases. The diversion ratio R of the valve system 4 is controlled by the control device 5.

  The control device 5 controls the operation of the fuel cell system 1. In the present embodiment, the control device 5 includes information on the accelerator operation amount of the driver from the accelerator 12 of the vehicle 10 and information such as the driving state of the vehicle 10 from various sensors 13 installed inside and outside the vehicle (for example, current vehicle speed, target vehicle speed). Etc.). Based on these pieces of information, the control device 5 calculates the FC power generation required power Prf (power generation required power), which is the amount of power that needs to be generated by the fuel cell 2, and the fuel cell 2 uses the calculated FC power generation required power Prf. The operations of the compressor 3 and the valve system 4 of the fuel cell system 1 are controlled so as to output.

  When expressed as a functional block for realizing the above functions, the control device 5 includes a determination unit 51 and a control unit 52 as shown in FIG.

  The determination unit 51 calculates the FC power generation required power Prf (see FIG. 2) to the fuel cell 2 based on information acquired from the accelerator 12 and the sensor 13, and supplies the fuel cell 2 to the fuel cell 2 based on the calculated FC power generation required power Prf. Determine the amount of oxidizing gas to be supplied.

  The control unit 52 controls the compressor 3 and the valve system 4 so as to supply the amount of oxidizing gas determined by the determination unit 51 to the fuel cell 2. In particular, in the present embodiment, the control unit 52 determines that the FC power generation required power Prf to the fuel cell 2 is less than a predetermined value (oxidizing gas supply control switching threshold Pth, see FIG. 2) (hereinafter, “low output request time”). In other words, the rotation speed of the compressor 3 is maintained at a predetermined fixed value or more, and the supply amount of the oxidizing gas to the fuel cell 2 is controlled by the shunt ratio R of the valve system 4, whereby the FC power generation required power Prf is reduced. In the case of rapid increase (for example, during acceleration operation), the quick response of the control for increasing the supply amount of the oxidizing gas can be enhanced. On the other hand, when the FC power generation required power Prf is greater than or equal to a predetermined value (oxidizing gas supply control switching threshold value Pth) (hereinafter also referred to as “normal time”), the control unit 52 sets the shunt ratio R of the valve system 4 to a predetermined value. While maintaining the fixed value, the supply amount of the oxidizing gas to the fuel cell 2 is controlled by the rotational speed of the compressor 3. In the present embodiment, the control for switching the element that mainly controls the supply amount of the oxidizing gas to the fuel cell 2 between the compressor 3 and the valve system 4 in accordance with the FC power generation required power Prf in this way is referred to as “oxidizing gas supply control”. "

  The control device 5 is physically an electronic circuit mainly including a known microcomputer including a CPU (Central Processing Unit), a RAM (Random Access Memory), a ROM (Read Only Memory), and an interface. Each function of the control device 5 described above loads various application programs held in the ROM into the RAM and executes them by the CPU, thereby operating various devices in the vehicle under the control of the CPU, as well as the RAM and ROM. This is realized by reading and writing data in. The control device 5 is mounted on the fuel cell vehicle 10 and can also be mounted as a part of an ECU that performs various controls of the vehicle.

  Next, the operation of the fuel cell system 1 according to this embodiment will be described with reference to FIG. FIG. 2 is a flowchart of the oxidizing gas supply control performed by the fuel cell system 1 according to the embodiment. Each process of the oxidant gas supply control shown in the flowchart of FIG. 2 is performed by the control device 5 of the fuel cell system 1 at predetermined intervals, for example.

  In step S1, the FC power generation required power Prf is calculated by the determination unit 51 of the control device 5. For example, the determination unit 51 calculates the FC power generation required power Prf as the sum of the motor power consumption Pmot consumed by the drive motor 11 and the auxiliary machine power consumption Paux consumed by the auxiliary machine of the vehicle drive system (Prf = Pmot + Paux). When the process of step S1 is completed, the process proceeds to step S2.

  In step S2, the FC power generation request power Prf calculated in step S1 by the determining unit 51 is less than a predetermined oxidizing gas supply control switching threshold Pth (Prf <Pth), and the travel mode of the fuel cell vehicle 10 is It is determined whether or not the sports mode state (Fsp = ON). The determination unit 51 can acquire information on whether or not the current travel mode of the fuel cell vehicle 10 is a sports mode state from a device in the vehicle 10 such as an ECU.

  When the above condition is satisfied as a result of the determination in step S2 (Yes in step S2), the control for the low output request mainly using the valve system 4 is selected. That is, in step S3, the compressor rotation speed command value Nrf is set to a fixed value, and in step S4, the diversion ratio R of the valve system 4 is calculated from the FC power generation required power Prf calculated in step S1. When the processes of steps S3 and S4 are completed, the process proceeds to step S7.

  On the other hand, when the above condition is not satisfied as a result of the determination in step S2 (No in step S2), control for normal time mainly using the compressor 3 is selected. That is, in step S5, the compressor rotation speed command value Nrf is calculated from the FC power generation required power Prf calculated in step S1, and in step S6, the diversion ratio R of the valve system 4 is set to a fixed value. When the processes of steps S5 and S6 are completed, the process proceeds to step S7.

  In step S7, the control unit 52 of the control device 5 executes the rotational speed command of the compressor 3 and the opening command of the valve system 4 based on the command value calculated in steps S3, S4 or steps S5, S6. The That is, the control unit 52 controls the rotation speed of the compressor 3 based on the command value, and controls the valve opening degree of the valve system 4. When the process of step S7 is completed, this control flow ends.

  In the flowchart of FIG. 2, the compressor rotational speed command value Nrf calculated in step S3, S4 or step S5, S6 and the diversion ratio R of the valve system 4 are “the FC power generation required power Prf by the determining unit 51 of the control device 5”. The amount of the oxidizing gas supplied to the fuel cell 2 determined based on “.

  Next, effects of the fuel cell system 1 according to the present embodiment will be described. The fuel cell system 1 of this embodiment is mounted on a fuel cell vehicle 10. The fuel cell system 1 includes a fuel cell 2 that generates power by reacting a fuel gas and an oxidizing gas, a compressor 3 that compresses and supplies the oxidizing gas to the fuel cell 2, and a fuel cell 2 and a compressor 3. Then, the oxidizing gas compressed by the compressor 3 is divided into the fuel cell 2 and the bypass channel 7, and the supply amount of the oxidizing gas to the fuel cell 2 and the bypass channel 7 is adjusted. The controller 3 determines the amount of oxidizing gas to be supplied to the fuel cell 2 based on the required FC power generation power Prf, and the compressor 3 to supply the fuel cell 2 with the amount of oxidizing gas determined by the determining unit 51. And a control unit 52 of the control device 5 that controls the valve system 4. When the FC power generation required power Prf to the fuel cell 2 is less than a predetermined value (oxidizing gas supply control switching threshold value Pth), the control unit 52 holds the rotational speed of the compressor 3 at a predetermined fixed value or more, and also the fuel cell 2 The supply amount of the oxidizing gas to is controlled by the valve system 4.

  With this configuration, when the FC power generation required power Prf is less than a predetermined value, the compressor 3 of the fuel cell system 1 is not stopped, for example, even when the driver is not performing an accelerating operation. The number holds a predetermined fixed value or more. That is, the amount of oxidizing gas supplied to the fuel cell 2 can be reduced without reducing the rotational speed of the compressor 3. For this reason, even when the driver performs a reacceleration operation, even if the FC power generation required power Prf to the fuel cell 2 increases rapidly, the rotational speed of the compressor 3 can be quickly controlled to a desired value. The amount of oxidizing gas determined by 51 can be supplied to the fuel cell 2 without delay, and as a result, power generation can be performed so that the driver's acceleration request can be suitably satisfied.

  The effect of this embodiment will be further described with reference to FIG. FIG. 3 is a time chart showing the behavior of the fuel cell system 1 and the fuel cell vehicle 10 when the oxidizing gas supply control of FIG. 2 is performed. 3A is the accelerator opening of the fuel cell vehicle 10, FIG. 3B is the FC power generation required power Prf, FIG. 3C is the rotation speed of the compressor 3, and FIG. 3D is the air flow rate (for example, the compressor 3 and the valve system). 4), (E) is the FC output power Pfc (the amount of power actually output from the fuel cell 2), and (F) is the fuel cell vehicle 10. The vehicle speed, (G), indicates the diversion ratio R of the valve system 4. In FIG. 3, the behavior of the fuel cell system 1 of the present embodiment is shown by a solid line graph, and the behavior of the configuration in which the oxidizing gas supply control of the present embodiment as a comparative example is not performed is shown by a dotted line graph.

  In FIG. 3, as shown in FIG. 3A, from the state where the accelerator operation is performed at a predetermined accelerator opening, the driver stops the acceleration operation at time t <b> 0 and the accelerator opening becomes 0 (fully closed). Then, a case where the acceleration / deceleration operation of the fuel cell vehicle 10 in which the driver performs the acceleration operation again at time t2 and the accelerator opening increases to a predetermined value will be described as an example. In this case, as shown in (B), the determination unit 51 of the control device 5 starts the FC power generation request together with the decrease in the accelerator opening at time t0 from the state where the FC power generation required power Prf of the predetermined value is held. The power Prf is decreased, and the FC power generation required power Prf is set to 0 at a time t1 later than the accelerator fully closed timing. Further, the FC power generation required power Prf is increased at time t2 in accordance with the increase in the accelerator opening, and the FC power generation required power Prf is set to the predetermined value at time t3 later than the timing at which the accelerator opening reaches the predetermined value. In the example of FIG. 3, the period from time t0 to time t3 is “FC power generation required power Prf is less than a predetermined oxidizing gas supply control switching threshold Pth (Prf <Pth)” described with reference to FIG. ing.

  With respect to the behavior of the accelerator opening and the FC power generation required power Prf shown in FIGS. 3 (A) and 3 (B), as shown by the dotted lines in FIGS. 3 (C) to 3 (F), the oxidizing gas supply control of the present embodiment. In the case of the comparative example in which the control is not performed, the compressor 3 is stopped in response to the accelerator fully closing operation at time t0, and the air flow rate in the oxidizing gas supply flow path 6 is also zero. For this reason, after the reacceleration operation is performed at time t3, it takes time for the compressor 3 rotation speed and the air flow rate to reach the desired values, whereby the FC output power Pfc and the vehicle speed reach the desired values. It takes time to do so. As a result, a time lag occurs before the driver reaches the desired vehicle speed for the reacceleration operation of the driver at time t3, and the response does not satisfy the driver's acceleration request.

  On the other hand, in the fuel cell system 1 of the present embodiment, control of the diversion ratio R of the valve system 4 is added as shown in FIG. Specifically, in the normal time (before time t0 and after time t3), the diversion ratio R is fixed at zero. That is, all of the oxidizing gas flowing through the oxidizing gas supply channel 6 is supplied to the fuel cell 2 and does not flow into the bypass channel 7. During this period, the amount of oxidant gas supplied to the fuel cell 2 is controlled by the rotational speed of the compressor 3. That is, in this period, the processes of steps S5 and S6 in the flowchart of FIG. 2 are performed.

  On the other hand, in the period from time t0 to time t3 when the FC power generation required power Prf is less than the predetermined oxidizing gas supply control switching threshold Pth (Prf <Pth), the shunt ratio R is calculated from the FC power generation required power Prf, and FC It fluctuates based on the power generation required power Prf. As shown in FIGS. 3B and 3G, during the period from time t0 to t1 when the FC power generation required power Prf decreases, the shunt ratio R increases and the time t1 to t2 when the FC power generation required power Prf becomes 0. In this period, the diversion ratio R is fixed at 1, and the diversion ratio R is reduced in the period from time t2 to t3 when the FC power generation required power Prf increases. That is, the proportion of the oxidizing gas flowing through the oxidizing gas supply channel 6 at time t0 to t1 is increased to the bypass channel 7, and all of the oxidizing gas flowing through the oxidizing gas supply channel 6 at time t1 to t2 is bypassed. The flow to the path 7 is stopped and the supply to the fuel cell 2 is stopped, and the rate at which the oxidizing gas is diverted to the bypass flow path 7 at the times t2 to t3 decreases.

  By controlling the valve system 4 as described above, as shown by solid lines in FIGS. 3C to 3F, the supply of the oxidizing gas to the fuel cell 2 can be suitably suppressed at the time of low output request at times t0 to t3. Therefore, the rotation speed of the compressor 3 and the air flow rate can be maintained so as to be a predetermined amount or more. As a result, after the reacceleration operation is performed at time t3, the rise until the rotation speed of the compressor 3 and the air flow rate reach the desired values can be made faster than the comparative example, and the FC output power Pfc and the vehicle speed can be set as desired. The rise time to reach the value can also be shortened. As a result, the fuel cell system 1 according to the present embodiment preferably satisfies the driver's acceleration request because the vehicle speed rises quickly and the acceleration response is improved with respect to the driver's reacceleration operation at time t3. The response is

  Next, a modification of the fuel cell system 1 according to this embodiment will be described.

  In the oxidant gas supply control, the control for the low output request mainly using the valve system 4 shown in steps S3 and S4 in the flowchart of FIG. 2 is performed even when the drive motor 11 is switched to regeneration when the vehicle 10 is decelerated. A configuration in which this control is continuously performed and the motor regenerative power is consumed by the compressor 3 may be employed. With this configuration, by continuously rotating the compressor 3 at a predetermined value or higher, the regenerative power of the drive motor 11 can be instantaneously consumed by the compressor 3 even when the regeneration of the drive motor 11 rapidly increases. This makes it possible to realize a vehicle deceleration with a quicker response.

  Further, when performing the control for when the low output is required and the control for consuming the motor regenerative power by the compressor 3, the operation of the driver who places particular emphasis on drivability may be set as the implementation condition. When the control for the low output request is performed, the power consumption of the compressor 3 remains large even if the FC power generation required power Prf is small, and the fuel consumption of the vehicle deteriorates. Under normal circumstances, the deterioration of fuel consumption is contrary to the driver's intention, but in situations where the driver places importance on drivability, such as when sports mode is selected, the effect (acceleration responsiveness) of the above-mentioned control for the low output request is worse than the deterioration of fuel consumption. Improvement) is given priority. The fuel cell system 1 according to this embodiment makes it possible to switch between fuel efficiency-oriented and drivability-oriented control according to the driver's intention.

  This point is also reflected in the determination process in step S2 of the flowchart shown in FIG. 2 as a condition that “the traveling mode of the fuel cell vehicle 10 is the sports mode state (Fsp = ON)”. However, this condition is not essential, and the condition of step S2 is “the FC power generation required power Prf calculated in step S1 is less than a predetermined oxidizing gas supply control switching threshold Pth (Prf <Pth)”. You may limit only to conditions.

  Further, in the control for when the low output is required and the control for consuming the motor regenerative power by the compressor 3, the upper limit is set so that the rotation speed of the compressor 3 can be continuously operated for a predetermined time or more. The configuration may be variable according to the user's preference and vehicle state. With this configuration, it is possible to realize the above-mentioned control for a low output request for a long time, and also according to the driver's preference for drivability (for example, using the DMD indicator) and the vehicle state and environment such as vehicle speed, gradient, and altitude. Thus, by changing the holding rotation speed, a balance point between fuel efficiency and drivability can be determined, and the merchantability of the vehicle can be improved.

  Further, in the control for when the low output is required and the control in which the motor regenerative power is consumed by the compressor 3, the sensor value indicating the state of the vehicle or the unit related to the control is monitored, and these measured values are predetermined. It may be configured to prohibit or cancel the execution of the control when the threshold is reached. With this configuration, the vehicle speed, compressor temperature, humidity of the humidification module, remaining amount of fuel, etc. are monitored, and it is judged whether the control can be performed, thereby deteriorating merchantability, damage to vehicle parts, and user safety. Can be prevented.

  In addition, the valve system 4 applied in the above embodiment may be a diversion part capable of diverting the oxidizing gas compressed by the compressor 3 to the fuel cell 2 and the bypass flow path 7, and a configuration other than the valve may be applied. .

  The embodiments described above are for facilitating the understanding of the present invention, and are not intended to limit the present invention. Each element included in the embodiment and its arrangement, material, condition, shape, size, and the like are not limited to those illustrated, and can be changed as appropriate. In addition, the structures shown in different embodiments can be partially replaced or combined.

  DESCRIPTION OF SYMBOLS 1 ... Fuel cell system, 2 ... Fuel cell, 3 ... Compressor, 4 ... Valve system (distribution part), 5 ... Control apparatus, 51 ... Determination part, 52 ... Control part, 7 ... Bypass flow path, 10 ... Fuel cell vehicle ,

Claims (1)

A fuel cell system mounted on a fuel cell vehicle,
A fuel cell that generates electricity by reacting a fuel gas and an oxidizing gas; and
A compressor for compressing and supplying the oxidizing gas to the fuel cell;
Supplying the oxidizing gas to the fuel cell and the bypass flow path, which is arranged between the fuel cell and the compressor and diverts the oxidizing gas compressed by the compressor into the fuel cell and the bypass flow path. A diversion part for adjusting the amount,
A determination unit that determines an amount of the oxidizing gas to be supplied to the fuel cell based on power generation required power to the fuel cell;
A controller that controls the compressor and the diverter so as to supply the fuel cell with the amount of the oxidizing gas determined by the determiner;
With
The control unit maintains the rotation speed of the compressor at a predetermined value or higher when the power generation required power to the fuel cell is less than a predetermined value, and supplies the oxidizing gas supply amount to the fuel cell by the flow dividing unit. Control,
Fuel cell system.