JP2019145220A - Fuel cell system - Google Patents

Abstract

To provide a fuel cell system capable of circumventing high potential of fuel cell, while restraining calorific value of a reactor.SOLUTION: A fuel cell system includes a first battery, a first battery converter including a reactor, an external feeding part, a fuel cell, a converter for fuel cell, a second battery, a second battery converter, and a control section. The second battery converter is connected in parallel with the first battery converter for the converter for fuel cell, on the reverse side to the connection side with the second battery. The control section controls the second battery converter so that the value of power supplied from the second battery becomes smaller than a value obtained by subtracting the value of power supplied from the fuel cell from a continuous rating, i.e., the upper limit of power for using the first battery converter continuously by maintaining a state where the calorific value of the reactor is equal to or less than a predetermined upper limit.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a fuel cell system.

  A fuel cell system is known that includes an external power supply unit and a battery on the output side of a battery converter having a reactor, and a fuel cell on the input side of the converter (for example, Patent Document 1).

Japanese Patent Laying-Open No. 2015-220961

  In such a fuel cell system, by increasing the voltage difference between the battery side and the inverter side of the converter, the amount of heat generated by the reactor is suppressed from increasing. On the other hand, in a fuel cell, it is known that when the electrode potential becomes too high, elution of a catalytic metal such as platinum occurs and the electrode catalyst changes its form. When such a change in the shape of the electrode catalyst proceeds, the performance of the fuel cell may be degraded. In the fuel cell system of Patent Document 1, an aspect in which another battery is further provided on the input side than the battery converter and a plurality of power supplies including the fuel cell is not considered. The inventor, for example, restricts the supply of power to the converter by restricting the supply of power from the fuel cell without restricting the supply of power from another battery in order to suppress the amount of heat generated by the reactor. In this case, it has been found that the current cannot be taken out from the fuel cell to suppress the deterioration of the fuel cell (hereinafter also referred to as “high potential avoidance”).

  The present invention has been made to solve the above-described problems, and can be realized as the following forms or application examples.

According to one form of the present disclosure, a fuel cell system is provided. The fuel cell system includes: a first battery; a first battery converter including a reactor and connected to the first battery; connected to the first battery in parallel with the first battery converter and supplying power to an external load An external power supply unit for supplying the first battery converter; a fuel cell connected to a side opposite to the side where the first battery is connected to the first battery converter; and between the fuel cell and the first battery converter A fuel cell converter for converting the output voltage of the fuel cell; a second battery; a second battery converter connected to the second battery; and a control unit. The second battery converter is connected in parallel to the first battery converter with respect to the fuel cell converter on the side opposite to the side connected to the second battery. The controller is configured to continuously use the first battery converter while maintaining a state where the value of electric power supplied from the second battery is equal to or lower than a predetermined upper limit value of the heating value of the reactor. The second battery converter is controlled so as to be smaller than a value obtained by subtracting a value of power supplied from the fuel cell from a continuous rated value that is an upper limit value of power.
According to the fuel cell system of this embodiment, the value of the electric power supplied to the first battery converter can be made smaller than the continuous rated value of the first battery converter by adjusting the value of the electric power supplied from the second battery. . Therefore, it can suppress that the emitted-heat amount of the reactor of a 1st battery converter becomes large. Further, according to the fuel cell system of this embodiment, the value of the electric power supplied from the fuel cell is not limited. Therefore, it is possible to avoid high potential by taking out current from the fuel cell in order to suppress elution of the catalyst metal of the fuel cell. That is, according to the fuel cell system of the present embodiment, it is possible to avoid the high potential of the fuel cell while suppressing the amount of heat generated by the reactor.

  A plurality of constituent elements of each embodiment of the present invention described above are not essential, and some or all of the effects described in the present specification are to be solved to solve part or all of the above-described problems. In order to achieve the above, it is possible to appropriately change, delete, replace with another new component, and partially delete the limited contents of some of the plurality of components. In order to solve some or all of the above-described problems or achieve some or all of the effects described in this specification, technical features included in one embodiment of the present invention described above. A part or all of the technical features included in the other aspects of the present invention described above may be combined to form an independent form of the present invention.

1 is a schematic diagram illustrating a configuration of a fuel cell vehicle 10 including a fuel cell system 100 as an embodiment of the present disclosure. It is a flowchart of the control performed by the control part 180 of the fuel cell system of this embodiment.

A. First embodiment:
FIG. 1 is a schematic diagram illustrating a configuration of a fuel cell vehicle 10 including a fuel cell system 100 according to an embodiment of the present disclosure. The fuel cell system 100 includes a fuel cell 110, a first battery 140, a second battery 160, a fuel cell converter 120, a power control unit (hereinafter also referred to as “PCU”) 130, a motor 136, an air A compressor (hereinafter also referred to as “ACP”) 138 and a control unit 180 are provided. PCU 130 includes a first battery converter 134, a second battery converter 164, a motor inverter 132, and an ACP inverter 137.

  The fuel cell vehicle 10 travels using electric power output from the fuel cell 110, the first battery 140, and the second battery 160 as a driving force. The fuel cell vehicle 10 of this embodiment also functions as an external power supply system, and supplies electric power to an external load (not shown) while the vehicle is stopped.

  In this specification, “when the fuel cell vehicle 10 is stopped” represents a state in which no electric power is supplied from the fuel cell 110, the first battery 140, and the second battery 160 to the motor 136 described later. The state in which the movement of the fuel cell vehicle 10 is restricted by a parking brake (so-called side brake) is also included in this state. “Fuel cell vehicle 10 is stopped” does not include a so-called idling state in which acceleration can be started by an accelerator operation. “When the fuel cell vehicle 10 is traveling” represents a state in which the motor 136 is driven using at least one power of the fuel cell 110, the first battery 140, and the second battery 160. “When the fuel cell vehicle 10 is traveling” includes the idling state described above.

  The fuel cell 110 is a polymer electrolyte fuel cell that generates power by receiving supply of hydrogen and air (specifically, oxygen) as reaction gases. The first battery 140 and the second battery 160 are storage batteries configured by, for example, nickel metal hydride batteries or lithium ion batteries. The fuel cell 110 is not limited to a polymer electrolyte fuel cell, and various other types of fuel cells can be employed. The first battery 140 and the second battery 160 are not limited to nickel metal hydride batteries and lithium ion batteries, and other various types of chargeable / dischargeable batteries can be employed.

  The control unit 180 is configured by a microcomputer including a CPU, a ROM, a RAM, and the like. The control unit 180 receives a switching operation by a driving mode switching switch (not shown) by the driver and switches the driving mode of the fuel cell vehicle 10. Here, the fuel cell vehicle 10 of the present embodiment has a “normal traveling mode” and a “power supply mode” as operation modes.

  The “normal operation mode” is a mode for causing the fuel cell vehicle 10 to travel based on a driver's operation. When the normal operation mode is selected, the control unit 180 accepts an operation such as an accelerator operation by the driver, and generates power from the fuel cell 110, charges the first battery 140, and the second battery 160 according to the operation content. Control the discharge. On the other hand, the “power supply mode” is a mode in which the fuel cell vehicle 10 functions as the fuel cell system 100 that supplies electric power to an external load while the fuel cell vehicle 10 is stopped.

  The fuel cell 110 is connected to the high-voltage DC wiring DCH via the fuel cell converter 120 and is connected to the motor inverter 132 and the ACP inverter 137 included in the PCU 130 via the high-voltage DC wiring DCH. The first battery 140 is connected to a first battery converter 134 included in the PCU 130 via a low-voltage DC wiring DCL1. The first battery converter 134 is connected to the high-voltage DC wiring DCH. The second battery 160 is connected to a second battery converter 164 included in the PCU 130 via a low-voltage DC wiring DCL2. Second battery converter 164 is connected to high-voltage DC wiring DCH.

  That is, the fuel cell 110 is connected to the first battery converter 134 on the side opposite to the side where the first battery 140 is connected. The fuel cell converter 120 is connected between the fuel cell 110 and the first battery converter 134. Second battery converter 164 is connected to second battery 160. Second battery converter 164 is connected in parallel to first battery converter 134 to fuel cell converter 120 on the side opposite to the side connected to second battery 160.

  The fuel cell converter 120, the first battery converter 134, and the second battery converter 164 are constituted by DC / DC converters. The fuel cell converter 120 boosts the output voltage VFC of the fuel cell 110 to a high voltage VH that can be used by the motor inverter 132 and the ACP inverter 137. The fuel cell converter 120 adjusts the current value of the fuel cell 110 by changing the switching frequency of the internal switching element in accordance with a command from the control unit 180. In the present embodiment, the fuel cell converter 120 includes an FC power detection unit 122.

  The FC power detection unit 122 is a sensor that measures a power value Pf supplied to the first battery converter 134 via the high-voltage DC wiring DCH. The FC power detection unit 122 acquires a voltage value detected by a voltage sensor (not shown) provided in the fuel cell converter 120 and a current value extracted from the fuel cell 110, and the first battery converter 134. The power value Pf supplied to is detected. The power value Pf detected by the FC power detection unit 122 is transmitted to the control unit 180.

  The motor inverter 132 is constituted by a three-phase inverter circuit. The motor inverter 132 is connected to a motor 136 that drives wheels (not shown). The motor inverter 132 is supplied via the output power of the fuel cell 110 supplied via the fuel cell converter 120 and the first battery 140 and the second battery converter 164 supplied via the first battery converter 134. The power output from the second battery 160 is converted into three-phase AC power and supplied to the motor 136. The motor 136 is configured by a synchronous motor having a three-phase coil.

  Similar to the motor 136, the ACP 138 is driven by a synchronous motor including a three-phase coil. The ACP 138 is connected to the ACP inverter 137. Similar to motor inverter 132, ACP inverter 137 is configured by a three-phase inverter circuit. The ACP inverter 137 converts the power output from the fuel cell 110 and the power output from the first battery 140 and the second battery 160 into three-phase AC power and supplies it to the ACP 138. The ACP 138 supplies air to the fuel cell 110 according to the rotation of the motor.

  In the normal travel mode, control unit 180 transmits a drive signal corresponding to the accelerator opening to motor inverter 132, first battery converter 134, and second battery converter 164. The motor inverter 132 adjusts the pulse width of the AC voltage according to the drive signal of the control unit 180, and causes the motor 136 to rotate according to the accelerator opening. As a result, the fuel cell vehicle 10 travels.

  The first battery converter 134 includes a reactor 135 therein, adjusts the voltage of the high-voltage DC wiring DCH in accordance with a drive signal from the control unit 180, and switches the charging / discharging state of the first battery 140. The first battery converter 134 converts the output voltage VBAT of the secondary battery into a high voltage VH that can be used by the motor inverter 132 when the first battery 140 is in a discharged state. When the first battery 140 is in a charged state, the first battery converter 134 converts the high voltage VH output from the fuel cell converter 120 and the second battery converter 164 into a low voltage VL that can charge the first battery 140. Convert. For example, when the regenerative power is generated in the motor 136 with the second battery converter 164 turned off, the regenerative power is converted into DC power by the motor inverter 132, and the first power is converted via the first battery converter 134. The battery 140 is charged. The first battery converter 134 adjusts the current value of the fuel cell 110 by changing the switching frequency of the internal switching element in accordance with a command from the control unit 180. The first battery converter 134 has an electric power upper limit value (hereinafter referred to as “continuous rating”) for continuously using the first battery converter 134 while maintaining the heat generation amount of the reactor 135 below a predetermined upper limit value. Pc) is also set.

  Second battery converter 164 adjusts the voltage of high-voltage DC wiring DCH in accordance with the drive signal from control unit 180 and switches the charging / discharging state of second battery 160. The second battery converter 164 converts the output voltage VBAT of the secondary battery into a high voltage VH that can be used by the motor inverter 132 when the second battery 160 is in a discharged state. The second battery converter 164 converts the high voltage VH output from the fuel cell converter 120 and the first battery 140 into a low voltage VL that can charge the second battery 160 when the second battery 160 is in a charged state. To do. For example, when regenerative power is generated in the motor 136 while the first battery converter 134 is off, the regenerative power is converted into direct current power by the motor inverter 132, and the second power is converted via the second battery converter 164. The battery 160 is charged. In the present embodiment, the second battery converter 164 includes a second battery power detection unit 162.

  The second battery power detection unit 162 is a sensor that measures a power value Pb supplied to the first battery converter 134 via the high-voltage DC wiring DCH. The second battery power detection unit obtains a voltage value detected by a voltage sensor (not shown) provided in the second battery converter 164 and a current value taken out from the second battery 160 to obtain a second value. The power value Pb supplied from the battery converter 164 to the first battery converter 134 is detected. The power value Pb detected by the second battery power detection unit 162 is transmitted to the control unit 180.

  The control unit 180 acquires the power value Pf detected by the FC power detection unit 122 and the power value Pb detected by the second battery power detection unit 162, and based on the acquired power value, the first battery converter The value of the power supplied to 134 can be determined. Control unit 180 sets an upper limit value of power supplied to first battery converter 134 in the control of second battery converter 164. More specifically, the control unit 180 subtracts the power value Pb supplied from the fuel cell 110 from the continuous rated value Pc set in the first battery converter 134 from the power value Pb supplied from the second battery 160. Control to make the value smaller than the above value is executed for second battery converter 164.

  The external power supply unit 170 is a power supply device for supplying power to an external load. The external power supply unit 170 is connected to the low-voltage DC wiring DCL1. That is, the external power supply unit 170 is connected in parallel with the first converter with respect to the first battery. The external power feeding unit 170 is driven by a part of power supplied from the fuel cell 110, the first battery 140, and the second battery 160. The external power supply unit 170 supplies the DC power from the low voltage DC wiring DCL1 to the external power supply device 174.

  An external power supply device 174 for connecting an external load that operates with AC power can be connected to the external power supply unit 170. By connecting the external power supply device 174 to the external power supply unit 170, the fuel cell vehicle 10 functions as an external power supply system, and is connected to the external power supply device 174 from the fuel cell 110, the first battery 140 and the second battery 160. Power is supplied to the external load (not shown). The external power supply device 174 converts the DC power supplied from the external power supply unit 170 into AC power of AC 100V, and supplies the power to an external load connected to a commercial power outlet.

  FIG. 2 is a flowchart of control executed by the control unit 180 of the fuel cell system according to this embodiment. The control unit 180 is activated and starts control by turning on the ignition key of the vehicle. The control unit 180 acquires the power value Pf detected by the FC power detection unit 122 and the power value Pb detected by the second battery power detection unit 162 (step S10).

  In step S20, the control unit 180 uses the continuous rated value Pc set in the first battery converter 134 and the acquired power value Pf and power value Pb, via the second battery converter 164, the first battery 140. Alternatively, the value of power supplied to the external power supply apparatus 174 is controlled. More specifically, the control unit 180 subtracts the power value Pb supplied from the fuel cell 110 from the continuous rated value Pc set in the first battery converter 134 from the power value Pb supplied from the second battery 160. Control to make the value smaller than the specified value is executed.

  When power value Pb is larger than a threshold set by multiplying a value obtained by subtracting power value Pf supplied from fuel cell 110 from continuous rated value Pc set in first battery converter 134 by a predetermined coefficient. (S20: NO), control unit 180 controls second battery converter 164 so as to reduce the value of power value Pb by adjusting the current value by changing the switching frequency of the internal switching element (step S30).

  When power value Pb is smaller than a threshold value set by multiplying a value obtained by subtracting power value Pf supplied from fuel cell 110 from continuous rated value Pc set in first battery converter 134 by a predetermined coefficient. (S20: YES), it is confirmed whether or not a condition for ending the control by the control unit 180 is satisfied (step S40). For example, when the ignition key of the vehicle is turned off, the control by the control unit 180 is ended (S40: YES). When the condition for ending the control is not satisfied (S40: NO), the control unit 180 returns to the process of step S10 and acquires the power value Pf and the power value Pb.

  As described above, according to the fuel cell system 100 of the present embodiment, by adjusting the power value Pb supplied from the second battery 160, the power value supplied to the first battery converter 134 is changed to the first battery converter 134. The continuous rating value Pc of 134 can be made smaller. Therefore, it is possible to suppress the amount of heat generated by reactor 135 of first battery converter 134 from increasing. Further, according to the fuel cell system 100, the power value Pf supplied from the fuel cell 110 is not limited. Therefore, in order to suppress elution of the catalyst metal of the fuel cell 110, it is possible to avoid a high potential by taking out current from the fuel cell 110. That is, according to the fuel cell system 100 of the present embodiment, it is possible to avoid the high potential of the fuel cell 110 while suppressing the amount of heat generated by the reactor 135.

B. Other embodiments:
The present invention is not limited to the above-described examples and embodiments, and can be implemented in various modes without departing from the gist thereof. For example, the present invention can be implemented in the following modes. is there.

B1. Other form 1:
(1) In the above embodiment, the fuel cell system 100 includes two batteries, the first battery 140 and the second battery 160. However, the fuel cell system is not limited to this, and may be configured to include three or more batteries. In such an aspect, the power is supplied from a plurality of other batteries than the value obtained by subtracting the power value supplied from the fuel cell from the continuous rated value of one battery converter having an external power feeding unit between the batteries. What is necessary is just to control so that the total of the electric power value to be performed becomes small.

(2) In the above-described embodiment, the control unit 180 of the fuel cell system 100 adjusts the current value by changing the switching frequency of the internal switching element to adjust the second battery converter 164 so that the power value Pb is reduced. Control. However, the control unit may adjust the voltage value of the second battery converter so as to reduce the power value Pb.

(3) In the above embodiment, the control unit 180 of the fuel cell system 100 controls the second battery converter 164 to reduce the power value Pb. However, a control part may perform control which stops supply of electric power from the 2nd battery in the 2nd battery converter.

(4) In the above embodiment, the fuel cell converter 120 includes the FC power detection unit 122, and the second battery converter 164 includes the second battery power detection unit 162. However, the fuel cell converter may not include the FC power detection unit, and the second battery converter may not include the second battery power detection unit. In such an aspect, the control unit obtains the power value according to the command to the second battery converter from the continuous rated value of the first battery converter, and the power value according to the command to the fuel cell converter. The second battery converter can be controlled to be smaller than the subtracted value.

  The present disclosure is not limited to the above-described embodiment, and can be realized with various configurations without departing from the spirit of the present disclosure. For example, the technical features in the embodiments corresponding to the technical features in each embodiment described in the summary section of the invention are intended to solve part or all of the above-described problems, or one of the above-described effects. In order to achieve part or all, replacement or combination can be appropriately performed. Further, if the technical feature is not described as essential in the present specification, it can be deleted as appropriate.

DESCRIPTION OF SYMBOLS 10 ... Fuel cell vehicle 100 ... Fuel cell system 110 ... Fuel cell 120 ... Fuel cell converter 122 ... FC electric power detection part 132 ... Motor inverter 134 ... First battery converter 135 ... Reactor 136 ... Motor 137 ... ACP inverter 140 ... First Battery 160 ... Second battery 162 ... Second battery power detection unit 164 ... Second battery converter 170 ... External power supply unit 174 ... External power supply device 180 ... Control unit DCH ... High voltage DC wiring DCL1 ... Low voltage DC wiring DCL2 ... Low voltage DC wiring Pb ... Power value Pc ... Continuous rated value Pf ... Power value VBAT ... Output voltage VFC ... Output voltage VH ... High voltage VL ... Low voltage

Claims (1)

A fuel cell system,
A first battery;
A first battery converter comprising a reactor and connected to the first battery;
An external power supply unit connected in parallel to the first battery converter with respect to the first battery, for supplying power to an external load;
A fuel cell connected to a side opposite to the side where the first battery is connected to the first battery converter;
A fuel cell converter connected between the fuel cell and the first battery converter for converting an output voltage of the fuel cell;
A second battery;
A second battery converter connected to the second battery;
A control unit,
The second battery converter is connected in parallel to the first battery converter with respect to the fuel cell converter on the side opposite to the side connected to the second battery.
The controller is configured to continuously use the first battery converter while maintaining a state where the value of electric power supplied from the second battery is equal to or lower than a predetermined upper limit value of the heating value of the reactor. A fuel cell system that controls the second battery converter to be smaller than a value obtained by subtracting a value of electric power supplied from the fuel cell from a continuous rated value that is an upper limit value of electric power.

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