Power supply system and power supply method

Abstract

The present application provides a power supply system and a power supply method capable of supplying appropriate power to an auxiliary machine while suppressing cost increase of the auxiliary machine. The power supply system of an embodiment includes a fuel cell capable of generating power, an electric storage device that accumulates power generated by the fuel cell, a converter that converts power from the fuel cell or the electric storage device and switches supply of power from the fuel cell to an auxiliary machine and supply of power from the electric storage device to the auxiliary machine, and a control unit that controls at least the switching in the converter.

Description

Technical Field

[0001] This invention relates to power supply systems and methods. Background Technology

[0002] Previously, technologies for supplying power from a fuel cell system mounted in a vehicle to vehicle auxiliary equipment were known (e.g., Japanese Patent Application Publication No. 2004-222376, Japanese Patent Application Publication No. 2005-251674, and Japanese Patent Application Publication No. 2007-335151). Summary of the Invention

[0003] However, the voltage output of a fuel cell can vary significantly due to factors such as scanning current and power generation conditions. Therefore, when power is directly supplied from the fuel cell to auxiliary equipment, an adjustment function corresponding to power fluctuations needs to be installed on the auxiliary equipment side, which may lead to high costs for auxiliary equipment and other components.

[0004] One aspect of the present invention was made in consideration of such circumstances, and one of its objectives is to provide a power supply system and power supply method capable of supplying appropriate power to auxiliary equipment while suppressing the high cost of auxiliary equipment.

[0005] The power supply system and power supply method of one aspect of the present invention adopt the following structure.

[0006] (1): A power supply system according to one aspect of the present invention includes: a fuel cell capable of generating electricity; an energy storage device that stores the electricity generated by the fuel cell; a converter that converts the electricity from the fuel cell or the energy storage device and switches the supply of electricity from the fuel cell to an auxiliary machine and the supply of electricity from the energy storage device to the auxiliary machine; and a control unit that controls at least the switching in the converter.

[0007] (2): In the above (1) scheme, the control unit obtains the state of the fuel cell and the state of the energy storage device, selects the fuel cell or the energy storage device to supply power to the auxiliary machine based on the obtained states, and controls the converter to supply power from the selected one to the auxiliary machine.

[0008] (3): In the above (1) scheme, the converter has a first terminal connected to the fuel cell, a second terminal connected to the energy storage device, and a third terminal connected to the auxiliary machine. Based on the control performed by the control unit, the converter switches the first terminal and the third terminal to a conducting state or a disconnected state, or switches the second terminal and the third terminal to a conducting state or a disconnected state, thereby switching the power supply to the auxiliary machine.

[0009] (4): In the above (3) scheme, when the control unit determines that the energy storage device needs to be charged based on the charging state of the energy storage device, it controls the converter to make at least the first terminal and the second terminal in a conducting state.

[0010] (5): In the above (4) scheme, the control unit converts the power from the fuel cell into a voltage value that is below the upper limit of the allowable voltage of the auxiliary machine to which the power is supplied and is greater than the voltage value of the energy storage device.

[0011] (6): In the above (1) scheme, the control unit controls the converter to use the power from the energy storage device as the power for starting the fuel cell.

[0012] (7): Another aspect of the present invention provides a power supply method in which the control unit of the power supply system performs the following processing: obtaining the state of a fuel cell capable of generating electricity and the state of an energy storage device that stores the electricity generated by the fuel cell; selecting, based on the obtained states, either the fuel cell or the energy storage device, one of which supplies power to an auxiliary machine; and controlling a converter to supply power from the selected one to the auxiliary machine, the converter transforming the power from the fuel cell or the energy storage device and switching the supply of power from the fuel cell to the auxiliary machine and the supply of power from the energy storage device to the auxiliary machine.

[0013] According to any of the schemes in (1) to (7) above, it is possible to supply appropriate power to the auxiliary equipment while suppressing the high cost of the auxiliary equipment connected to the power supply system. Attached Figure Description

[0014] Figure 1 This is a diagram illustrating a simplified structure of the power supply system according to an implementation method.

[0015] Figure 2 This is a diagram illustrating an example of the structure of the energy ECU in an implementation method.

[0016] Figure 3 This is a diagram illustrating an example of the structure of a DC-DC converter according to an implementation method.

[0017] Figure 4 This is a flowchart illustrating an example of the processing flow performed by the power supply system of the implementation method. Detailed Implementation

[0018] Hereinafter, embodiments of the power supply system and power supply method of the present invention will be described with reference to the accompanying drawings. The following description will primarily focus on the case where the power supply system is mounted on a vehicle. The vehicle is, for example, an electric vehicle that uses electricity generated by the fuel cell (described later) or electricity stored in an energy storage device for driving or for operating onboard equipment (auxiliary equipment). The vehicle is, for example, a two-wheeled, three-wheeled, or four-wheeled motor vehicle.

[0019] Figure 1 This diagram illustrates a simplified structure of the power supply system 1 according to an embodiment. The power supply system 1 includes, for example, a fuel cell 100, a battery 200, a DC-DC converter 300, and an energy ECU (Electronic Control Unit) 400. The battery 200 is an example of an "energy storage device." The energy ECU 400 is an example of a "control unit." A main output device 120 and one or more auxiliary units 500-1, 500-2, ..., 500-n are connected to the power supply system 1. The main output device 120 and the auxiliary units 500 are examples of "loads." Hereinafter, without distinguishing between the auxiliary units 500-1, 500-2, ..., 500-n, they will be collectively referred to as "auxiliary unit 500."

[0020] The fuel cell 100 is, for example, a battery that generates electricity by reacting hydrogen contained in fuel gas with oxygen contained in air. The fuel cell 100 generates electricity, for example, under the control of an energy ECU. The fuel cell 100 outputs the generated electricity to, for example, a main output device 120, or to a DC-DC converter 300 via a DC line or the like. The main output device 120 is a motor that uses the electricity from, for example, the fuel cell 100 to output driving force for the vehicle's movement to the drive wheels. The main output device 120 can also be other devices for moving or stopping the vehicle (e.g., a braking device). The main output device 120 can also be connected to the fuel cell 100 via a converter or the like.

[0021] The fuel cell 100 may also be equipped with a fuel cell sensor to detect whether the fuel cell 100 is generating electricity, the electrical power being generated, the temperature, etc. The detection results of the fuel cell sensor are output to the energy ECU 400, for example.

[0022] The storage battery 200 is, for example, a lithium-ion battery, a nickel-metal hydride battery, a lead-acid battery, or a rechargeable battery that can be repeatedly charged and discharged. The storage battery 200 may also be a battery with a lower voltage (e.g., 12V, 48V) compared to the power generated by the fuel cell 100. The storage battery 200 may also be a battery unit obtained by connecting multiple individual battery cells. The storage battery 200 may store power generated in the fuel cell 100 and converted by the DC-DC converter 300 (for charging), or supply the power stored in the storage battery 200 to auxiliary equipment 500, etc. (for discharging).

[0023] The battery 200 may also be equipped with battery sensors (current sensor, voltage sensor, temperature sensor) to detect the current value, voltage value, temperature, etc. of the battery 200. The detection results of the battery sensors are output to the energy ECU 400, for example.

[0024] The DC-DC converter 300 converts DC power from the fuel cell 100 or the battery 200 and supplies the converted DC power to auxiliary equipment 500, etc. For example, the DC-DC converter 300, under the control of the energy ECU 400, boosts or bucks the DC power from the fuel cell 100 or the battery 200 to a specified power value required by the auxiliary equipment 500. The DC-DC converter 300, under the control of the energy ECU 400, switches the supply of DC power (hereinafter referred to as "power") from the fuel cell 100 to the auxiliary equipment 500 and the supply of power from the battery 200 to the auxiliary equipment 500. The DC-DC converter 300, under the control of the energy ECU 400, can also convert power from the fuel cell 100 and supply it to the battery 200.

[0025] The energy ECU 400 controls the supply of power to the main output device 120 and the auxiliary unit 500. For example, the energy ECU 400 controls at least the switching between the supply of power from the fuel cell 100 to the auxiliary unit 500 in the DC-DC converter 300 and the supply of power from the battery 200 to the auxiliary unit 500. Details regarding the function of the energy ECU 400 are described later.

[0026] Auxiliary device 500 is, for example, a device that uses power supplied from fuel cell 100 or battery 200 via DC-DC converter 300 for operation. Auxiliary device 500 can also be electrical equipment installed in the vehicle other than main output device 120. Auxiliary device 500 includes, for example, vehicle sensors, display devices, lighting devices, navigation devices, communication devices, driving recorders, HMI (Human Machine Interface), and other in-vehicle equipment.

[0027] <Energy ECU>

[0028] Next, the details of the functions of the energy ECU400 will be explained. Figure 2 This diagram illustrates an example of the structure of an energy ECU 400 according to an embodiment. The energy ECU 400 includes, for example, a status acquisition unit 420, a supply control unit 440, a switching control unit 460, and a power control unit 480. The status acquisition unit 420, supply control unit 440, switching control unit 460, and power control unit 480 are each implemented, for example, by executing programs (software) using a hardware processor such as a CPU (Central Processing Unit). Some or all of these components can also be implemented using hardware (including the circuitry) such as LSI (Large Scale Integration), ASIC (Application Specific Integrated Circuit), FPGA (Field-Programmable Gate Array), and GPU (Graphics Processing Unit), or through a combination of software and hardware.

[0029] The status acquisition unit 420 acquires the power requirements, operating status, etc., of each of the more than one auxiliary machine 500-1 to 500-n connected to the DC-DC converter 300. For example, when it receives a message that the vehicle's ignition switch is turned on, or when it receives an operation from the occupant via an HMI, it acquires the power requirements from the auxiliary machine that corresponds to the received information. The status acquisition unit 420 communicates with the auxiliary machine 500 that is starting (operating) at predetermined intervals or at predetermined times, or receives operating signals (e.g., normal signals, abnormal signals) from the auxiliary machine 500, thereby acquiring the operating status of the auxiliary machine 500. The status acquisition unit 420 can also acquire the status of the vehicle equipped with the power supply system 1 (e.g., information detected by vehicle sensors).

[0030] The status acquisition unit 420 acquires the status of the fuel cell 100 and the status of the battery 200 based on the detection results of sensors (fuel cell sensor and battery sensor) respectively installed in, for example, the fuel cell 100 and the battery 200. The status of the fuel cell 100 includes, for example, whether the fuel cell 100 is generating electricity, the power generation status when generating electricity (e.g., the amount of electricity generated in a specified time), the degree of degradation, and whether any abnormality has occurred. The status of the battery 200 includes, for example, whether the battery 200 is charging or discharging, the state of charge of the battery 200 (e.g., SOC (State of Charge)), the degree of degradation, and whether any abnormality has occurred.

[0031] The supply control unit 440 selects either the fuel cell 100 or the battery 200 to supply power to the auxiliary machine 500 based on the power requirements from the auxiliary machine 500 obtained by the status acquisition unit 420, the status of the fuel cell 100 and the battery 200. For example, the supply control unit 440 calculates the required power for the power requirements from the auxiliary machine 500. For example, the supply control unit 440 calculates the torque that the motor should output based on the vehicle's throttle opening and vehicle speed, and calculates the required power by summing the drive shaft load power calculated based on the torque and motor speed and the power required by at least one of the multiple auxiliary machines. The supply control unit 440 may also pre-store the required power for each auxiliary machine's operation and calculate the required power by referring to the stored required power. When there are power requirements from multiple auxiliary machines, the supply control unit 440 calculates the total value of the required power from each auxiliary machine. Furthermore, the supply control unit 440 compares the calculated required power with the SOC of the battery 200, and selects the battery 200 if it is determined that the power can be supplied by the battery 200, and selects the fuel cell 100 if it is determined that the power cannot be supplied by the battery 200.

[0032] The supply control unit 440 can, for example, select the battery 200 when the fuel cell 100 is not started, or when the fuel cell 100 is started, and select the fuel cell 100 when the fuel cell 100 is started (operating). In this case, the supply control unit 440 controls the DC-DC converter 300 to use the power from the battery 200 as the power for starting the fuel cell 100.

[0033] The supply control unit 440 can also select either the fuel cell 100 or the battery 200 based on the type and quantity of the auxiliary machines 500 that require power. For example, if an auxiliary machine needs to be started immediately, the supply control unit 440 selects the battery 200, which can immediately supply stored power. If the number of auxiliary machines 500 receiving power is less than a predetermined number, the supply control unit 440 selects the battery 200; if the number of auxiliary machines 500 receiving power is greater than or equal to a predetermined number, the fuel cell 100 is selected because the power of the battery 200 will be consumed immediately.

[0034] The supply control unit 440 may also select the battery 200 when an abnormality occurs in the fuel cell 100, and select the fuel cell 100 when an abnormality occurs in the battery 200. The supply control unit 440 may also select the battery 200 when the degree of degradation of the fuel cell 100 is above a reference value, and select the fuel cell 100 when the degree of degradation of the battery 200 is above a reference value. The supply control unit 440 may also select the fuel cell 100 or the battery 200 based on an instruction from a user (for example, an occupant of a vehicle equipped with the power supply system 1, a system administrator), etc.

[0035] The switching control unit 460 controls a switching unit (described later) included in the DC-DC converter 300 to supply power from the fuel cell 100 or the battery 200 selected by the supply control unit 440 to the auxiliary machine 500 or the like.

[0036] Based on the states of the fuel cell 100 and the battery 200 acquired by the state acquisition unit 420, the power supply status of supplying power to the main output device 120 and the auxiliary machine 500, etc., the power control unit 480 performs power generation control of the fuel cell 100, charge or discharge control of the battery 200, etc. For example, when the SOC calculated based on the output of the battery sensor included in the battery 200 is less than a threshold value, the power control unit 480 determines that the battery 200 needs to be charged, and executes control (charge control) for charging the battery 200 by power generation by the fuel cell 100. When the SOC of the battery 200 is above the threshold value, the power control unit 480 determines that the battery 200 does not need to be charged, and executes control to stop the charge control. For example, when there is surplus power generated by the fuel cell 100, the power control unit 480 may also perform control for charging the battery 200 or consuming power by the auxiliary machine 500 or the like.

[0037] <Switching control in the DC-DC converter>

[0038] Next, the content of the switching control in the DC-DC converter 300 will be specifically described. Figure 3 FIG. is an example of the structure of the DC-DC converter 300 according to the embodiment. The DC-DC converter 300 includes, for example, a conversion unit 320 and a switching unit 340.

[0039] The conversion unit 320 steps down or steps up the power supplied from the fuel cell 100 or the battery 200 corresponding to the required power amount of the auxiliary machine 500 with a power requirement.

[0040] The switching unit 340, under the control of the switching control unit 460, switches the power supply from the fuel cell 100 to the auxiliary unit 500 and the power supply from the battery 200 to the auxiliary unit 500. The switching unit 340 is, for example, a switching circuit or switching element such as an electromagnetic switch. For example, the switching unit 340 is like... Figure 3 The system shown includes at least a first terminal 360-1 connected to the fuel cell 100, a second terminal 360-2 connected to the battery 200, and a third terminal 360-3 connected to the auxiliary unit 500. The first terminal 360-1 connected to the fuel cell 100 includes both direct connection and connection via wires (electrically conductive wires). The same applies to the second terminal 360-2 connected to the battery 200 and the third terminal 360-3 connected to the auxiliary unit 500. Alternatively, if multiple auxiliary units 500-1 to 500-n exist in the power supply system 1, the third terminal 360-3 may be provided for each connected auxiliary unit.

[0041] The switching unit 340, for example, switches the on / off states between the first terminal 360-1, the second terminal 360-2, and the third terminal 360-3, based on the control of the switching control unit 460. For instance, when the supply control unit 440 selects to supply power from the fuel cell 100 to the auxiliary machine 500, the switching control unit 460 outputs a control signal to the switching unit 340 to make the first terminal 360-1 and the third terminal 360-3 on / off, and to make the second terminal 360-2 and the third terminal 360-3 off / off. When the supply control unit 440 selects to supply power from the battery 200 to the auxiliary machine 500, the switching control unit 460 outputs a control signal to the switching unit 340 to make the second terminal 360-2 and the third terminal 360-3 on / off, and to make the first terminal 360-1 and the third terminal 360-3 off / off.

[0042] When the charging of the storage battery 200 is controlled by the power control unit 480, the switching control unit 460 outputs a control signal to the switching unit 340 to make at least the first terminal 360-1 and the second terminal 360-2 in a conductive state. When charging the storage battery 200, the first terminal 360-1 and the third terminal 360-3 can be either in an open circuit or a conductive state. In this case, when the conversion unit 320 converts the power from the fuel cell 100, the power control unit 480 converts the power from the fuel cell 100 to a voltage value that is below the upper limit of the allowable voltage of the auxiliary machine 500 to which power is supplied and higher than the voltage value of the storage battery 200. Therefore, the voltage value of the storage battery 200 is lower than the converted voltage value, so even if the first terminal 360-1 and the third terminal 360-3 are in a conductive state, power flows to the storage battery 200 side, enabling the storage battery 200 to be charged. When the power control unit 480 supplies power from the fuel cell 100 to the storage battery 200, it can also enable the conversion unit 320 to perform power conversion in a manner close to the upper limit of the allowable voltage of the auxiliary machine 500.

[0043] Even when no power is supplied from the fuel cell 100 to the storage battery 200 and auxiliary machine 500, the switching control unit 460 can also output control signals to the switching unit 340 to make the circuit between the first terminal 360-1 and the second terminal 360-2, and between the first terminal 360-1 and the third terminal 360-3, open.

[0044] The switching unit 340 controls the switching of states between terminals based on the control signals from the switching control unit 460. This allows the DC-DC converter 300 to adjust the power from the fuel cell 100 and the battery 200 to a predetermined voltage and supply it to all auxiliary equipment 500-1 to 500-n. Therefore, it eliminates the need for a function to adjust power fluctuations in the auxiliary equipment 500, thus reducing the cost of the auxiliary equipment 500.

[0045] [Processing Flow]

[0046] Figure 4 This is a flowchart illustrating an example of the processing flow performed by the power supply system 1 in this embodiment. Figure 4In the example, the status acquisition unit 420 determines whether a power request has been received from the auxiliary machine 500 (step S100). If a power request has been received from the auxiliary machine 500, the status acquisition unit 420 acquires the status of the fuel cell and the battery 200 (step S102). Next, the supply control unit 440 selects either the fuel cell 100 or the battery 200 to supply power to the auxiliary machine 500 based on the status acquired by the status acquisition unit 420 (step S104). Next, the switching control unit 460 controls the DC-DC converter 300 to switch the on / off state between each terminal (first terminal 360-1, second terminal 360-2, and third terminal 360-3) to supply power from the selected terminal to the auxiliary machine 500 (step S106). The power control unit 480 converts the power from the DC-DC converter 300 based on the power requirements from the auxiliary machine 500 (step S108), and supplies the converted power to the auxiliary machine (step S110).

[0047] Next, the supply control unit 440 determines whether the battery 200 needs charging based on its state of charge (e.g., SOC) (step S112). If it is determined that the battery needs charging, the switching control unit 460 controls the DC-DC converter 300 to supply power from the fuel cell 100 to the battery 200 (step S114). In the process of step S114, the DC-DC converter 300, for example, based on the control from the switching control unit 460, switches the first terminal 360-1 and the second terminal 360-2 to a conducting state. The power control unit 480 causes the fuel cell 100 to generate electricity and supplies it to the battery 200 via the DC-DC converter 300 (step S116). Through the process of step S116, the battery 200 is charged. Thus, the process of this flowchart ends. If, in step S100, it is determined that no power request has been received from the auxiliary machine 500, or in step S112, it is determined that the battery does not need to be charged, the flowchart ends.

[0048] It could also be that, after execution Figure 4If, after the processing of step S110, it is not necessary to supply power to the auxiliary machine 500, the switching control unit 460 switches the on / off states between the terminals (first terminal 360-1, second terminal 360-2, and third terminal 360-3) of the DC-DC converter 300 to prevent power from the fuel cell 100 or the battery 200 from being supplied to the auxiliary machine 500. Alternatively, if, after the processing of step S116, it is not necessary to supply power to the battery 200 (e.g., when the SOC is above a threshold), the switching control unit 460 controls the switching of the first terminal 360-1 and the second terminal 360-2 of the DC-DC converter 300 to an off-circuit state to prevent power from the fuel cell 100 from being supplied to the battery 200.

[0049] exist Figure 4 In the process shown, steps S100 to S110 (hereinafter referred to as the first process) and steps S112 to S116 (hereinafter referred to as the second process) can be executed separately. In this case, if one of the first and second processes is being executed, the energy ECU 400 can be controlled to not execute the other process (standby until the other process is completed), or the first and second processes can be separated and executed in parallel through time sharing. The energy ECU 400 can also prioritize the first process over the second process, or execute the second process without executing the first process.

[0050] According to the embodiments described above, the power supply system 1 includes: a fuel cell 100 capable of generating electricity; a battery (an example of an energy storage device) 200 that stores the power generated by the fuel cell 100; a DC-DC converter (an example of a converter) 300 that converts the power from the fuel cell 100 or the battery 200, and switches the supply of power from the fuel cell 100 to the auxiliary machine 500 and the supply of power from the battery 200 to the auxiliary machine 500; and an energy ECU (an example of a control unit) 400 that controls at least the switching in the DC-DC converter 300, thereby enabling the supply of appropriate power to the auxiliary machine while suppressing the high cost of the auxiliary machine connected to the power supply system.

[0051] Specifically, in the power supply system 1 of the embodiment, for example, a DC-DC converter 300 is provided between the fuel cell 100 and the auxiliary unit 500, and the DC-DC converter 300 is connected to a battery 200 with a lower voltage (e.g., 12V, 48V) compared to the fuel cell 100. Furthermore, the DC-DC converter 300 boosts or bucks the power from the fuel cell 100 and the power from the battery 200 to supply a stable voltage (e.g., a constant voltage) to the auxiliary unit 500. Therefore, even if the power output from the fuel cell 100 changes, or if the fuel cell 100 and the battery 200 are connected with different voltage values, there is no need for voltage adjustment functions on the auxiliary unit side. As a result, the cost of the auxiliary unit 500 can be reduced, and the reusability of the auxiliary unit 500 can be improved.

[0052] According to the embodiment, the DC-DC converter 300 has a first terminal 360-1 connected to the fuel cell 100, a second terminal 360-2 connected to the battery 200, and a third terminal 360-3 connected to the auxiliary machine 500. The on and off states between the terminals are switched according to the power supply source and the power supply target. In this way, not only can the power of the fuel cell 100 or the battery 200 be supplied to the auxiliary machine 500, but the power of the fuel cell 100 can also be supplied to the battery 200 to charge the battery 200.

[0053] The fuel cell 100 in this embodiment is an example of a battery that generates electricity through the reaction of hydrogen and oxygen, but various other fuel cell applications are also possible. Some or all of the functions of the energy ECU 400 in this embodiment can also be incorporated into the DC-DC converter 300. The power supply system 1 in the above embodiments can be used in vehicles (or alternatively) as well as in other electric devices (e.g., ships, aircraft, robots), or in stationary fuel cell systems.

[0054] The above description illustrates specific embodiments of the present invention, but the present invention is not limited to such embodiments in any way, and various modifications and substitutions can be made without departing from the spirit of the present invention.

Claims

1. A power supply system, wherein, The power supply system has the following features: Fuel cells capable of generating electricity; An energy storage device that stores the electricity generated by the fuel cell; A converter that transforms power from the fuel cell or the energy storage device, and switches the supply of power from the fuel cell to the auxiliary equipment and the supply of power from the energy storage device to the auxiliary equipment; and The control unit controls at least the switching in the converter. The converter has a first terminal connected to the fuel cell, a second terminal connected to the energy storage device, and a third terminal connected to the auxiliary machine. The converter, based on control by the control unit, switches the connection between the first terminal and the third terminal to a conducting or disconnected state, or switches the connection between the second terminal and the third terminal to a conducting or disconnected state, thereby switching the power supply to the auxiliary machine. When the control unit determines that the energy storage device needs charging based on its charging status, it controls the converter to make at least the first terminal and the second terminal in a conductive state. The control unit converts the power from the fuel cell into a voltage value that is below the upper limit of the allowable voltage of the auxiliary machine to which the power is supplied and greater than the voltage value of the energy storage device, so that the power from the fuel cell is supplied to both the auxiliary machine and the energy storage device.

2. The power supply system according to claim 1, wherein, The control unit obtains the status of the fuel cell and the status of the energy storage device. Based on the obtained status, it selects either the fuel cell or the energy storage device to supply power to the auxiliary machine, and controls the converter to supply power from the selected device to the auxiliary machine.

3. The power supply system according to claim 1 or 2, wherein, The control unit controls the converter to use the power from the energy storage device as starting power for the fuel cell.

4. A method for supplying electricity, wherein, The control department of the power supply system performs the following processing: The state of the fuel cell capable of generating electricity and the state of the energy storage device that stores the electricity generated by the fuel cell are obtained. Based on the obtained states, select either the fuel cell or the energy storage device to supply power to the auxiliary machine. as well as The control converter supplies power from the selected party to the auxiliary machine, the converter transforms power from the fuel cell or the energy storage device, and switches the supply of power from the fuel cell to the auxiliary machine and the supply of power from the energy storage device to the auxiliary machine. The converter has a first terminal connected to the fuel cell, a second terminal connected to the energy storage device, and a third terminal connected to the auxiliary machine. The converter, based on control by the control unit, switches the connection between the first terminal and the third terminal to a conducting or disconnected state, or switches the connection between the second terminal and the third terminal to a conducting or disconnected state, thereby switching the power supply to the auxiliary machine. When the control unit determines that the energy storage device needs charging based on its charging status, it controls the converter to make at least the first terminal and the second terminal in a conductive state. The control unit converts the power from the fuel cell into a voltage value that is below the upper limit of the allowable voltage of the auxiliary machine to which the power is supplied and greater than the voltage value of the energy storage device, so as to control the power from the fuel cell to be supplied to both the auxiliary machine and the energy storage device.

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