JP2008022628A - Power conversion device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a power conversion device capable of carrying out efficient conversion over a wide region of the input power. <P>SOLUTION: The power conversion device 1 converts power supplied from a power source 2 and supplies it to a load. The device has multiple converters 4, 5, 6 that are different in rated outputs and are connected in parallel and includes a control means 7 that varies a combination of converters to be operated from among the converters 4, 5, 6 according to the power supplied from the power source 2. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a power conversion device used in, for example, an automobile.

Conventionally, in a power conversion device such as a DC / DC converter, there is a technique described in Patent Document 1, for example, as a technique for improving efficiency in a wide input voltage fluctuation range and output voltage fluctuation range. In the power conversion device described in Patent Document 1, a plurality of converters having different circuit systems are connected in parallel, and one of the converters is selected based on the input voltage condition and / or the output voltage condition. It has been proposed to select a power conversion circuit. Moreover, although there exist some which are described in patent document 2 as a power converter device which raises efficiency, in the power converter device described in this patent document 2, several converters of the same characteristic are connected in parallel Thus, the sharing of output power is adjusted.
Japanese Patent Laid-Open No. 6-311729 JP 2004-178877 A

  However, the power conversion device described in Patent Document 1 has a problem that the power required for the circuit operation of the power conversion device becomes apparent in a region where the input power is low, and the efficiency is reduced in the region where the input power is low. Also, in the power conversion device described in Patent Document 2, because a plurality of converters having the same characteristics are connected in parallel, in a region where the input power is low, the low efficiency portions of the individual converters overlap, This also has a problem that efficiency is lowered.

  In view of the above problems, an object of the present invention is to provide a power converter that can perform highly efficient conversion in a wide range of input power.

In order to solve the above problem, a power conversion device according to the present invention provides:
A power conversion device that converts power supplied by a power source and supplies it to a load,
In parallel with multiple converters with different rated outputs,
Control means for changing a combination of converters to be operated among the plurality of converters according to electric power supplied from the power source.

Here, load sharing ratio determination means for determining the load sharing ratio between the converters according to a predetermined load sharing ratio map,
Based on the load sharing ratio determined by the load sharing ratio map, comprising load sharing ratio search means for searching for a load sharing ratio that maximizes the efficiency of the power converter,
It is preferable that the control unit selects and controls a converter to be operated among the plurality of converters based on the load sharing ratio searched by the load sharing ratio search unit.

  According to this, the control content when the control means selects the plurality of converters can be simplified.

  Furthermore, it is preferable to include a load sharing ratio updating unit that updates the load sharing ratio map based on the load sharing ratio that maximizes the efficiency of the power conversion device searched by the load sharing ratio searching unit.

  According to this, it is possible to reduce the time for searching for the load sharing ratio that maximizes the efficiency of the power conversion apparatus from the next time onward, and to always optimize the load sharing ratio of the load sharing ratio map.

  ADVANTAGE OF THE INVENTION According to this invention, the power converter device which can perform highly efficient conversion in the wide area | region of input electric power can be provided.

  The best mode for carrying out the present invention will be described below with reference to the accompanying drawings.

  FIG. 1 is a circuit diagram showing an embodiment of a power converter according to the present invention, and FIG. 2 is a circuit diagram showing a configuration of a DC / DC converter used in the embodiment of the power converter according to the present invention. It is.

  The power conversion device 1 according to the present embodiment converts the power supplied by the waste heat recovery stack 2 and supplies it to the battery device 3, and includes DC / DC converters 4, 5 as converters having different rated outputs. 6 are connected in parallel, and the control ECU 7 is configured to change and select and control the combination of the DC / DC converters to be operated among the DC / DC converters 4, 5, 6.

  The waste heat recovery stack 2 generates heat by converting the thermal energy of the exhaust gas of the automobile into electrical energy using a thermoelectric element made of, for example, a Bi-Te-based or Si-Ge-based semiconductor material. This thermoelectric element is disposed between an exhaust manifold (not shown) through which an exhaust gas flows, and a gas pipe provided between the exhaust pipe and a cooling pipe through which engine cooling water flows. One surface is cooled by the cooling water in the cooling pipe, and the other surface is heated by the exhaust gas in the gas passage, thereby generating a temperature difference in the thermoelectric element to generate power.

  The battery device 3 is composed of, for example, a Pb battery 3a and a battery ECU (Electronic Control Unit) 3b, and is charged by power supplied from the power conversion device 1. Here, an air conditioner (not shown), a car audio device, Electric power is supplied to each in-vehicle device such as a car navigation device. The battery ECU 3b is composed of, for example, a CPU, a ROM, a RAM, and a data bus connecting them, and the CPU performs the following process according to a program stored in the ROM. The battery ECU 3b normally monitors the charge amount and the allowable charge amount of the Pb battery 3a, and transmits the allowable charge amount information to the control ECU 7 through, for example, CAN (Controller Area Network).

  The DC / DC converter 4 is a flyback type DC / DC converter as shown in FIG. 2, for example, and includes a flyback transformer 8, a MOSFET 9, a diode 10, a capacitor 11, an input voltmeter 12, an input ammeter 13, and an input terminal 14. The output terminal 15 and the capacitor 16 are configured as main components. In this DC / DC converter 4, the current flowing in the primary winding of the flyback transformer 8 is controlled by PWM control of the MOSFET 9, and an AC voltage proportional to the winding ratio is applied to the secondary winding of the flyback transformer 8. The electric power generated and rectified to direct current by the diode 10 and the capacitor 11 is supplied to the battery device 3 with the boosted or stepped down power. The capacitor 16 is inserted for the purpose of lowering the input impedance.

  The input voltmeter 12 detects the input voltage of each DC / DC converter and the output voltage V and the open circuit voltage Voc of the waste heat recovery stack 2. The open circuit voltage Voc is measured in a state where the MOSFET 9 is turned off under the command of the control ECU 7.

  The circuit configurations of the DC / DC converter 5 and the DC / DC converter 6 connected in parallel to the DC / DC converter 4 are basically the same as the flyback DC / DC converter shown in FIG. Here, the rated output of the DC / DC converter 4 (converter 1) is 100 W, the rated output of the DC / DC converter 5 (converter 2) is 200 W, and the rated output of the DC / DC converter 6 (converter 3) is 400 W. It is said. The specifications of the flyback transformer, MOSFET, diode, and capacitor described above correspond to the rated outputs of the DC / DC converters 5 and 6, respectively, so that the DC / DC converters 5 and 6 having different rated outputs are provided. Is configured.

  The control ECU 7 (Electronic Control Unit) is composed of, for example, a CPU, a ROM, a RAM, and a data bus connecting them, and the CPU performs the processing described below in accordance with a program stored in the ROM. The control ECU 7 includes an estimated power generation amount calculation unit 7a, an allowable charge amount acquisition unit 7b, a converter processing power calculation unit 7c, a load sharing ratio determination unit 7d, a load sharing ratio search unit 7e, and a load sharing ratio update unit. 7f, a control unit 7g, and a current search unit 7h.

  Based on the open circuit voltage Voc detected by the input voltmeter 12, the estimated power generation amount calculation unit 7a is configured to calculate the estimated power generation amount Pin, current Iin, and voltage Vin of the waste heat recovery stack 2 as shown in FIG. Calculate using. The estimated power generation amount map shown in FIG. 3 is determined based on the power generation characteristic diagram of the waste heat recovery stack 2 as shown in FIG. In FIG. 4, the short-circuit current Is is obtained by measuring with the input ammeter 14 with the MOSFET 9 turned on in advance, and the current Iin for obtaining the estimated power generation amount Pin is obtained as a half value of the short-circuit current Is. The voltage Vin for obtaining the estimated power generation amount Pin is obtained as a half value of the open circuit voltage Voc, and Pin is obtained by the product of the current Iin and the voltage Vin. In FIG. 3, for the sake of convenience, the estimated power generation amount Pin, the current Iin, and the voltage Vin when the open circuit voltage Voc is changed in units of 5V are shown.

  The allowable charge amount acquisition unit 7 b acquires the allowable charge amount Pp transmitted from the battery ECU 3 b of the battery device 3.

  The converter processing power calculation unit 7c compares the estimated power generation amount Pin of the waste heat recovery stack 2 calculated by the supply power calculation unit 7a with the allowable charge amount Pp acquired by the required power acquisition unit 7b, and calculates the estimated power generation amount. When Pin is larger than allowable charge amount Pp, converter processing power = allowable charge amount Pp, otherwise, converter process power = estimated power generation amount Pin.

  The load sharing ratio determination unit 7d selects a DC / DC converter to be operated using a converter selection map as shown in FIG. 5 based on the converter processing power calculated by the converter processing power calculation unit 7c. . As illustrated in FIG. 5, when the converter processing power is 100 W or less, the load sharing ratio determination unit 7 d selects the 100 W DC / DC converter 4, and the converter processing power is greater than 100 W and 300 W or less. In some cases, 100W DC / DC converter 4 and 200W DC / DC converter 5 are selected, and when converter processing power is greater than 300W and less than 500W, 100W DC / DC converter 4 and 400W When the DC / DC converter 6 is selected and the converter processing power is greater than 500 W and 600 W or less, the 200 W DC / DC converter 5 and the 400 W DC / DC converter 6 are selected.

  In addition, the load sharing ratio determination unit 7d determines the load sharing ratio of each DC / DC converter among the selected combinations of DC / DC converters based on the open circuit voltage Voc detected by the input wattmeter 12 as shown in FIG. It is calculated using a load sharing ratio map as shown in FIG. Since the DC / DC converter of the present embodiment is current controlled, the load sharing ratio R is the value of one of the converters A of the two selected DC / DC converters (referred to as converters A and B for convenience). When the power is Pa, the current is Ia, the power of the other converter B is Pb, and the current is Ib, the load sharing ratio is represented by R = Pa / (Pa + Pb) = Ia / (Ia + Ib). Note that the estimated power generation amount map shown in FIG. 6 is experimentally obtained in advance by a method similar to the hill-climbing method described later in the power conversion device of this embodiment.

  The load sharing ratio search unit 7e searches for the load sharing ratio R at which the efficiency of the power conversion device 1 is actually maximized by the hill-climbing method with reference to the load sharing ratio R determined by the load sharing ratio determination unit 7d. The hill-climbing method will be described in detail in the description of the flowchart described later. The reason why the load sharing ratio R obtained in advance is different from the load sharing ratio at which the efficiency of the power converter 1 is actually maximized is that the flyback transformer 8, MOSFET 9, diode 10, and the like that constitute each DC / DC converter. This is due to the deterioration of the capacitor 11.

  The load sharing ratio update unit 7f searches for a corresponding portion of the load sharing ratio map shown in FIG. 6 based on the load sharing ratio R that the power conversion device 1 actually maximizes, searched by the load sharing ratio search unit 7e. Update.

  Based on the current Iin obtained by the estimated power generation amount calculation unit 7a, the load sharing ratio R determined by the load sharing ratio determining unit 7d, and the load sharing ratio R searched by the load sharing ratio searching unit 7e, the control unit 7g / DC converters 4, 5 and 6 are PWM controlled. At the same time, the current search unit 7h searches the current I having the maximum output with the current Iin as an initial value by a hill climbing method to be described later.

  The control content of the power converter according to the present invention described above will be described with reference to a flowchart. FIG. 7 is a flowchart showing the control contents of the power converter according to the present invention.

  In S010, the estimated power generation amount calculation unit 7a detects the open circuit voltage Voc by the input voltmeter 12, and in S020, the estimated power generation amount calculation unit 7a uses the estimated power generation amount map shown in FIG. , Current Iin, and voltage Vin are calculated. For example, if the open circuit voltage Voc = 20V, the estimated power generation amount Pin = P4, the current Iin = i4, and the voltage Vin = V4. Subsequently, in S030, the allowable charge amount acquisition unit 7b reads the allowable charge amount Pp from the battery ECU 3b via CAN. In S040, the converter processing power calculation unit 7c compares the estimated power generation amount Pin calculated by the estimated power generation amount calculation unit 7a with the allowable charge amount Pp acquired by the allowable charge amount acquisition unit 7b, and calculates the estimated power generation amount Pin. Is greater than the allowable charge amount Pp, the process proceeds to S050, and the converter processing power is set to the allowable charge amount Pp. If the estimated power generation amount Pin is smaller than the allowable charge amount Pp, the process proceeds to S060, and the converter process power is set. The estimated power generation amount Pp.

Based on the converter processing power obtained by the above-described processing of S050 and S060, the burden sharing ratio determination unit 7d first uses S / 70 to operate the converter to be operated using the converter selection map shown in FIG. A converter is selected and the number of motion converters N is calculated.
Furthermore, in S071, the load sharing ratio determination unit 7d calculates and calculates the load sharing ratio R between the selected converters, that is, the DC / DC converters, using the load sharing ratio map shown in FIG.

  Subsequently, in S080, the load sharing ratio search unit 7e determines whether or not the number of operation converters N = 1. If N = 1, the process proceeds to S090, and if N = 1, the process proceeds to S180. In this embodiment, if the number of operation converters N = 1, the converter processing power is 100 W or less and the DC / DC converter 4 is selected according to the converter selection map shown in FIG.

  The processes from S090 to S171 described below are processes for searching for the current I that is the maximum output by the hill-climbing method when the number of motion converters N = 1.

  In S090, using the current Iin calculated in S020 as the initial value of the current I, the control unit 7g performs PWM control on the DC / DC converter 4, and the current search is performed using the voltage V detected by the input voltmeter 12 and the current I. The unit 7h first calculates power P1 = I × V.

  Further, in S100, the current search unit 7h adds a small difference ΔI to the current I, and in S110, the control unit 7g performs PWM control on the DC / DC converter 4 based on the current I = I + ΔI, and the current search unit 7h. However, the power P2 = I × V is calculated from the voltage V detected by the input voltmeter 12 and the current I = I + ΔI.

  Furthermore, in S120, the current search unit 7h subtracts the minute difference 2ΔI from the current I. In S130, the control unit 7g performs PWM control on the DC / DC converter 4 based on the current I = I−2ΔI, and the current Search unit 7h calculates power P3 = I × V from voltage V detected by input voltmeter 12 and current I = I−2ΔI.

  In S140, when P1 is larger than P2 and P3, P1 is located on the top of the peak PI curve shown in FIG. = I + ΔI, the duty ratio duty = I / I (type) is calculated in S171, and the control unit 7g performs PWM control on the DC / DC converter 4 based on the duty ratio duty = I / I (type). In S171, I (typ) is a current when the duty ratio is 1.

  In S140, when P1 is not larger than P2 and P3, the process proceeds to S160, and the current search unit 7h determines whether P3 is larger than P2, and when P3 is larger than P2, FIG. In the PI curve shown in FIG. 4, P1 is located on the right side of the top of the mountain-shaped curve. Therefore, it is determined that it is descending to the right, the current I is left as it is, and the duty ratio duty = I / I ( The control unit 7g performs PWM control on the DC / DC converter 4 based on the duty ratio duty = I / I (type).

  In S160, when P3 is not larger than P2, the current search unit 7h is located on the right side of the top of the mountain-shaped PI curve shown in FIG. In S170, the current I = I + 2ΔI is set, and in S171, the duty ratio duty = I / I (type) is calculated. The control unit 7g PWMs the DC / DC converter 4 based on the duty ratio duty = I / I (type). Control.

  The search process of the current I that becomes the maximum output by the hill-climbing method from S090 to S171 is repeatedly performed unless IG OFF is detected in S175, and the current I is converged to the value that becomes the maximum output.

  If it is determined in S080 that the number of motion converters is not N = 1, the processing from S180 to S280 is executed, the subroutine PCALC shown in FIG. 9 is executed in S180, S200, and S220, and in S270, Subroutine PDEVIDE shown in FIG. 10 is executed. In the present embodiment, the case where the number of operation converters N is not 1 is a case where the converter processing power is 100 W or more and 600 W or less, and in any case, the number of operation converters N = 2.

  First, the subroutine PCALC shown in FIG. 9 will be described. Based on the load sharing ratio R determined by the load sharing ratio determination unit 7d in S071, the load sharing ratio search unit 7e converts in S310 the current Iin calculated by the estimated power generation amount calculation unit 7a in S020 as the initial value of the current I. The currents Ia = I × R and Ib = I−Ia = I × (1−R) of the devices A and B are calculated, the control unit 7g performs PWM control on the converters A and B, and the current search unit 7h Based on the voltage V detected by the input voltmeter 12 in the converter A and the current Ia = I × R, the power Pa = Ia × V of the converter A is calculated in S320, and the input voltage in the converter B is calculated in S330. Power Pb = Ib × V of converter B is calculated from voltage V detected by meter 12 and current Ib = I × (1−R). In S340, power P of the entire converter A and B P = Pa + Pb Calculate

  Next, the subroutine PDEVIDER shown in FIG. 10 will be described. Based on the load sharing ratio R determined by the load sharing ratio determination unit 7d in S071, the load sharing ratio search unit 7e converts in S410 the current Iin calculated by the estimated power generation amount calculation unit 7a in S020 as the initial value of the current I. The power P4 of the devices A and B is calculated using the subroutine PCALC shown in FIG. 9, and the slight difference ΔR is added to the load sharing ratio R in S420, and in S430, the load sharing ratio search unit 7e converts the converters A and B Is calculated using the subroutine PCALC shown in FIG. Further, in S440, the load sharing ratio search unit 7e subtracts the minute difference 2ΔR from the load sharing ratio R, and in S450, the load sharing ratio search unit 7e displays the power P6 of the converters A and B in the subroutine shown in FIG. Calculate using PCALC.

  In S460, when P4 is larger than P5 and P6, in the PR curve having an upwardly convex mountain shape shown in FIG. 11, P4 is positioned on the top of the mountain-shaped PR curve. The ratio search unit 7e sets the load sharing ratio R = R + ΔR, and in S500, the load sharing ratio update unit 7f updates the corresponding part of the load sharing ratio map shown in FIG. 6 and proceeds to S500 to finish the subroutine PDEVIDER.

  In S460, when P4 is not larger than P5 and P6, the process proceeds to S480, where the load sharing ratio search unit 7e determines whether P6 is larger than P5. When P6 is larger than P5, In the PR curve shown in FIG. 11, P4 is located on the right side of the top of the mountain-shaped curve. Therefore, it is determined that it is descending to the right, and the load sharing ratio R is left as it is, and the process proceeds to S510 and the subroutine PDEVIDER Exit.

  In S480, if P6 is not larger than P5, it is located on the right side of the top of the mountain-shaped PR curve shown in FIG. In S490, the load sharing ratio R = R + 2ΔR is set, and the process proceeds to S510, and the subroutine PDEVIDER is ended.

  The search process for the load sharing ratio R, which is the maximum output by the hill-climbing method from S400 to S510, is repeated unless an IG-off is detected in S175, and the load sharing ratio R converges to the maximum output, that is, the maximum efficiency value. Is done.

  In the following, from S180 to S280 shown in FIG. 8, the number of operation converters N = 2, that is, the process of searching for the current I that becomes the maximum output by the hill-climbing method when there are two selected converters A process for searching for the load sharing ratio R that maximizes the efficiency will be described.

  In S180, based on the estimated power generation amount calculated by the estimated power generation amount calculation unit 7a in S020 and the current I in that case and the load sharing ratio R determined by the load sharing ratio determination unit 7d in S071, the subroutine shown in FIG. First, power P1 = I × V = Ia × V + Ib × V is calculated by PCALC.

  Further, in S190, the current search unit 7h adds a small difference ΔI to the current I, and in S200, based on the current I = I + ΔI, the power P2 = I × V = Ia × V + Ib is executed by the subroutine PCALC shown in FIG. Calculate xV.

  Further, in S210, the current search unit 7h subtracts the minute difference 2ΔI from the current I, and in S220, based on the current I = I−2ΔI, the power P3 = I × V = Ia * V + Ib * V is calculated.

  In S230, when P1 is larger than P2 and P3, in the PI curve having an upward convex shape shown in FIG. 9, P1 is located at the top of the PI shape of the mountain shape. The section 7h sets the current I = I + ΔI, performs the search for the load sharing ratio R of the converters A and B that maximize the efficiency of the subroutine PDEVIDER shown in FIG. 10 in S270, and updates the load sharing ratio map in S280. Based on the load sharing ratio R, the control unit 7g calculates the duty ratio duty (A) = I × R / Ia (type), duty (B) = I × (1-R) / Ib (type), Based on the duty ratios duty (A) and duty (B), the control unit 7g performs PWM control on the converters A and B. In S280, Ia (typ) and Ib (typ) are currents when the duty ratio is 1 in each of converters A and B.

  In S230, when P1 is not larger than P2 and P3, the process proceeds to S250, where the current search unit 7h determines whether P3 is larger than P2, and when P3 is larger than P2, FIG. In the PI curve shown in FIG. 4, P1 is located on the right side of the top of the mountain-shaped curve. Therefore, it is determined that the current is descending to the right, and the current ratio I is left as it is, and the duty ratio duty (A) = I in S280. * R / Ia (typ), duty (B) = I * (1-R) / Ib (typ) is calculated, and the control unit 7g performs PWM control on the converters A and B.

  In S250, when P3 is not larger than P2, it is located on the right side of the top of the mountain-shaped PI curve shown in FIG. 8, so that the current search unit 7h is determined to rise to the right. In S260, current I = I + 2ΔI, and in S280, duty ratio duty (A) = I × R / Ia (type), duty (B) = I × (1−R) / Ib (type) is calculated, and control unit 7g Performs PWM control of the converters A and B.

  The search process of the current I that becomes the maximum output by the hill-climbing method from S180 to S280 is repeatedly performed unless IG OFF is detected in S175, and the current I is converged to the value that becomes the maximum output.

  According to the present embodiment described above, the following effects can be obtained. First, as shown in FIG. 12, the efficiency of converters represented by DC / DC converters varies depending on the power input to the converter, and the respective regions with high conversion efficiency vary depending on the power input to the converter. The efficiency is reduced in the region where the input power is smaller than the rated output.

  However, as shown in the present embodiment, a plurality of converters having different rated outputs are connected in parallel and selected according to the input power, that is, the estimated power generation amount of the waste heat recovery stack 2, and are shown in FIG. As described above, the efficiency can be increased for a wide range of input power. That is, when the converter 1 (100 W DC / DC converter 4) and the converter 2 (200 W DC / DC converter 5) are combined, the converter 1 compensates for the low efficiency region of the converter 2 and converts When the converter 1 and the converter 3 (400 W DC / DC converter 6) are combined, the converter 1 can compensate for the low efficiency region of the converter 3. In addition, when the converter 2 and the converter 3 are combined, the high-efficiency regions of the converters 2 and 3 overlap each other, so that the efficiency in the high input power region can be increased. As a result, the conversion efficiency of the power conversion device 1 can be increased in a wide range of input power. The effect of increasing the conversion efficiency becomes more prominent in a system using the waste heat recovery stack 2 in which the estimated power generation amount can vary over a wide range as in this embodiment.

  In addition, when the number of converters to be operated is one or plural, the optimum value of the current I can be searched and controlled so that the efficiency of the entire power conversion device 1 is increased. Can also increase efficiency.

  Furthermore, when there are a plurality of converters to be operated, the optimum value of the load sharing ratio R can be searched and controlled so that the efficiency of the entire power conversion device 1 is increased. Can be increased.

  Furthermore, by updating the load sharing ratio map shown in FIG. 6 based on the load sharing ratio R at which the efficiency of the power converter 1 is actually maximized, the load sharing at which the efficiency of the power converter is actually maximized is updated. The time for searching for the ratio after the next time can be shortened, and the load sharing ratio of the load sharing ratio map can always be optimized regardless of deterioration of elements constituting the converter.

  Although the embodiments have been described in detail, the present embodiments can be variously modified and replaced without departing from the scope of the present invention. In this embodiment, a flyback type DC / DC converter is used as the converter, but various types of converters such as a full bridge type DC / DC converter and a chopper type DC / DC converter can be used. is there.

  In this embodiment, the waste heat recovery stack is used as the power source and the battery device is used as the load. However, other configurations are possible. The modification is shown in FIGS.

  In FIG. 14, the power source of the present embodiment is replaced with a commercial power source from the waste heat recovery stack, the battery device as a load is replaced with a control device, and a plurality of converters having different rated outputs are converted from a DC / DC converter to an AC / DC. It is replaced with a converter and connected in parallel. In this case, the information acquired from the load by the control device is replaced with the estimated load amount from the allowable charge amount.

  FIG. 15 shows a case where the power source of this embodiment is replaced with a solar power generation device from a waste heat recovery stack, and a plurality of converters having different rated outputs are replaced with a DC / AC converter and connected in parallel. is there.

  In FIG. 16, the power source of this embodiment is replaced from the waste heat recovery stack with a three-phase AC power source system used in a hybrid vehicle, the load is a motor, and a plurality of converters having different rated outputs are DC / AC converters. They are connected in parallel.

  FIG. 17 shows a configuration in which the power source of this embodiment is replaced with a three-phase AC power source system used in a gasoline engine vehicle from a waste heat recovery stack, a load is a motor, and a plurality of converters having different rated outputs are DC / DC converters. And a DC-AC converter are connected in parallel.

  14 to 17, the estimated power generation amount map shown in FIG. 3 used in this embodiment, the motion converter map shown in FIG. 5, and the burden sharing ratio map shown in FIG. Replaced with a suitable one. In either configuration, a plurality of converters having different rated outputs are connected in parallel, and an operation converter is selected based on the estimated power generation amount (estimated supply power amount in the configuration shown in FIG. 14) and, in turn, the converter processing power. By searching for a load sharing ratio that provides maximum efficiency, high efficiency can be obtained in a wide range of input power.

  Furthermore, in this embodiment, three converters with different rated outputs are connected in parallel, and one or two of them are selected. Of course, three may be selected. Of course, it is possible to employ a configuration in which four or more converters having different rated outputs are connected in parallel.

  In the present invention, a converter having a different rated output is connected in parallel to a converter between a power source and a load, a converter processing power is obtained based on an estimated power generation amount and an allowable charge amount, and based on the converter processing power. The purpose is to increase the efficiency of the entire power conversion device by selecting the operation converter and optimizing the load sharing ratio between the operation converters, so passenger cars, trucks, buses, etc. It can be applied to various vehicles. In addition, the application target is not limited to vehicles, but can also be applied to devices that combine a generator, a load, and a converter, such as a solar power generation device, and convert power from the power source to the load to supply power. Any conversion device can be applied.

It is a block diagram which shows one Example of the power converter device which concerns on this invention. It is a circuit diagram of the DC / DC converter of the power converter device which concerns on this invention. It is an estimated power generation amount map of the power converter according to the present invention. It is a power generation characteristic view of the waste heat recovery stack of the power converter according to the present invention. It is a converter selection map of the power converter device which concerns on this invention. It is a load share ratio map of the power converter device which concerns on this invention. It is a flowchart which shows the control content of the power converter device concerning this invention. It is a schematic diagram which shows the concept of the process which searches the electric current used as the maximum output by the hill-climbing method of the power converter device concerning this invention. It is a flowchart which shows the control content of the power converter device concerning this invention. It is a flowchart which shows the control content of the power converter device concerning this invention. It is a schematic diagram which shows the concept of the process which searches the load sharing ratio used as the maximum output by the hill-climbing method of the power converter device concerning this invention. It is a schematic diagram which shows the efficiency of each converter of the power converter device concerning this invention. It is a schematic diagram which shows the efficiency of the power converter device concerning this invention. It is a block diagram which shows the other Example of the power converter device which concerns on this invention. It is a block diagram which shows the other Example of the power converter device which concerns on this invention. It is a block diagram which shows the other Example of the power converter device which concerns on this invention. It is a block diagram which shows the other Example of the power converter device which concerns on this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Power converter 2 Waste heat recovery stack 3 Battery apparatus 3a Pb battery 3b Battery ECU
4, 5, 6 DC / DC converter 7 Control ECU
8 Flyback transformer 9 MOSFET
10 Diode 11 Capacitor 12 Input Voltmeter 13 Input Ammeter 14 Input Terminal 15 Output Terminal 16 Capacitor

Claims (3)

A power conversion device that converts power supplied by a power source and supplies it to a load,
In parallel with multiple converters with different rated outputs,
A power conversion apparatus comprising: a control unit that changes a combination of converters to be operated among the plurality of converters according to power supplied from the power source. A load sharing ratio determining means for determining a load sharing ratio between the converters by a predetermined load sharing ratio map;
Based on the load sharing ratio determined by the load sharing ratio map, comprising load sharing ratio search means for searching for a load sharing ratio that maximizes the efficiency of the power converter,
2. The control unit according to claim 1, wherein the control unit selects and controls a converter to be operated among the plurality of converters based on the load sharing ratio searched by the load sharing ratio searching unit. Power conversion device.   3. A load sharing ratio update unit that updates the load sharing ratio map based on a load sharing ratio that maximizes the efficiency of the power conversion device searched by the load sharing ratio search unit. The power converter device described in 1.

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