JP7569137B2 - Fuel Cell Systems - Google Patents

Description

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

Some fuel cell systems installed in vehicles supply power output from a fuel cell to a load such as a traction motor via a power storage device provided downstream of the fuel cell, and also supply regenerative power output from the load to the power storage device.

However, the above fuel cell system has a problem in that if the capacity of the storage device is relatively small, the storage device is easily overcharged.

Therefore, if there is a risk that the regenerative power will cause the power storage device to become overcharged, it is possible to consume the power supplied from the fuel cell by driving auxiliary equipment related to the power generation of the fuel cell. Related technology is described in Patent Document 1.

JP 2015-144503 A

However, in the above fuel cell system, if the auxiliary equipment is forcibly operated to prevent the power storage device from becoming overcharged, particularly if the auxiliary equipment directly involved in the power generation of the fuel cell, such as the auxiliary equipment for supplying oxidant gas to the fuel cell, is forcibly operated, the output of the fuel cell may become high potential, which may cause the fuel cell to deteriorate.

Therefore, one object of the present invention is to prevent the fuel cell from deteriorating while preventing the power storage device from becoming overcharged in a fuel cell system.

One embodiment of the fuel cell system according to the present invention is a fuel cell system mounted on a vehicle, and includes a fuel cell, a power storage device connected between the fuel cell and a load mounted on the vehicle, auxiliary equipment driven by power supplied from the fuel cell, and a control unit that controls the power generation of the fuel cell and the operation of the auxiliary equipment.

When the regenerative power supplied from the vehicle to the fuel cell system is equal to or greater than a predetermined power and the acceleration of the vehicle is equal to or less than a predetermined acceleration, the control unit stops power generation by the fuel cell and drives the auxiliary equipment that is not directly involved in power generation by the fuel cell.

As a result, when the regenerative power is equal to or greater than a predetermined power and the vehicle acceleration is equal to or less than a predetermined acceleration, i.e., when the vehicle is likely traveling downhill and there is a risk of the power storage device becoming overcharged, it is possible to stop power generation by the fuel cell and drive auxiliary equipment that is not directly involved in power generation by the fuel cell. Therefore, even if the auxiliary equipment consumes the power supplied from the fuel cell, it is possible to prevent the output of the fuel cell from becoming a high potential, and deterioration of the fuel cell can be suppressed. In other words, it is possible to suppress deterioration of the fuel cell while suppressing the power storage device from becoming overcharged.

The control unit may be configured to stop power generation by the fuel cell when the regenerative power is equal to or greater than the predetermined power and when the acceleration is equal to or less than the predetermined acceleration, and then drive one or more of the multiple auxiliary devices according to the charge amount of the power storage device.

As a result, when there is a high possibility that the vehicle is traveling downhill and there is a risk that the storage device will become overcharged, the operation of one or more auxiliary devices can be appropriately controlled according to the charge level of the storage device, thereby preventing the storage device from becoming overcharged and suppressing deterioration of the fuel cell.

The control unit may be configured to increment a counter value when the regenerative power is equal to or greater than the predetermined power and the acceleration is equal to or less than the predetermined acceleration, to decrement the counter value when the regenerative power is less than the predetermined power or when the acceleration is greater than the predetermined acceleration, and to drive the auxiliary equipment that is not directly involved in the power generation of the fuel cell while stopping the power generation of the fuel cell when the counter value is equal to or greater than a first threshold value.

This makes it possible to prevent the fuel cell from frequently stopping and restarting power generation due to fluctuations in regenerative power and vehicle acceleration, thereby reducing the impact on the vehicle's driving caused by the fuel cell frequently stopping and restarting power generation, and preventing the driver from feeling uncomfortable when the vehicle is driving.

The control unit may also be configured to prepare to drive the auxiliary equipment that is not directly involved in power generation by the fuel cell when the counter value becomes equal to or greater than a second threshold value that is smaller than the first threshold value.

This allows the auxiliary equipment to be driven to consume power supplied from the fuel cell immediately after the counter value reaches or exceeds the first threshold value, compared to when preparations to drive the auxiliary equipment are not made before the counter value reaches or exceeds the first threshold value, thereby further preventing the power storage device from becoming overcharged.

The power storage device may also be configured as a capacitor.

Generally, among secondary batteries, capacitors have a relatively small capacity and excellent charge/discharge characteristics, so by configuring the power storage device using a capacitor, the charge/discharge characteristics of the fuel cell system can be made relatively high.

According to the present invention, in a fuel cell system, it is possible to prevent the power storage device from becoming overcharged while also preventing the fuel cell from deteriorating.

1 is a diagram illustrating an example of a fuel cell system according to an embodiment. 5A and 5B are diagrams illustrating an example of a current and a voltage output from a fuel cell. 10 is a flowchart showing an example of an operation of a control unit during a downhill flag switching process. 5 is a flowchart showing an example of an operation of a control unit during power generation control processing.

The following describes the embodiment in detail with reference to the drawings.

Figure 1 shows an example of a fuel cell system according to an embodiment.

The fuel cell system 1 shown in FIG. 1 is mounted on a vehicle Ve, such as an industrial vehicle such as a forklift or an automobile, and supplies power to a load Lo, etc. The load Lo is, for example, an inverter for driving a traction motor mounted on the vehicle Ve.

The fuel cell system 1 also includes a fuel cell FC, a hydrogen tank HT, a hydrogen tank valve HTV, an injector INJ, a gas-liquid separator GLS, a hydrogen circulation pump HP, an exhaust/drain valve EDV, an air compressor ACP, an air pressure regulating valve ARV, an air shutoff valve ASV, a radiator R, a fan F, a water pump WP, an intercooler IC, a DCDC converter CNV, a power storage device B, and a control unit 2. The hydrogen tank valve HTV, the injector INJ, the hydrogen circulation pump HP, the exhaust/drain valve EDV, the air compressor ACP, the air pressure regulating valve ARV, the air shutoff valve ASV, the fan F, and the water pump WP are auxiliary devices that consume power supplied from the fuel cell FC (DCDC converter CNV). In particular, the consumption of the power supplied from the fuel cell FC increases as the rotation speed of the motors for driving the hydrogen circulation pump HP, the air compressor ACP, the fan F, and the water pump WP is increased. In addition, the accessories such as the air compressor ACP and the injector INJ are considered to be accessories directly involved in the power generation of the fuel cell FC. In addition, the accessories such as the hydrogen circulation pump HP, the fan F, and the water pump WP are considered to be accessories not directly involved in the power generation of the fuel cell FC. In other words, the accessories directly involved in the power generation of the fuel cell FC can be rephrased as accessories that additionally supply reactant gas (fuel gas and oxidant gas described below) to the fuel cell FC, and the accessories not directly involved in the power generation of the fuel cell FC can be rephrased as accessories that do not additionally supply reactant gas to the fuel cell FC.

A fuel cell FC is a fuel cell stack consisting of multiple fuel cell cells connected in series with each other, and generates electricity through an electrochemical reaction between the hydrogen contained in the fuel gas (such as hydrogen gas) and the oxygen contained in the oxidant gas (such as air).

The hydrogen tank HT is a storage container for fuel gas. The fuel gas stored in the hydrogen tank HT is supplied to the fuel cell FC via the hydrogen tank valve HTV and the injector INJ.

The hydrogen tank valve HTV reduces the pressure of the fuel gas supplied to the fuel cell FC.

The injector INJ adjusts the flow rate of fuel gas supplied to the fuel cell FC.

The gas-liquid separator GLS separates the fuel gas and liquid water discharged from the fuel cell FC.

The hydrogen circulation pump HP supplies the fuel gas separated by the gas-liquid separator GLS back to the fuel cell FC.

The exhaust drain valve EDV discharges the liquid water separated by the gas-liquid separator GLS to the outside.

The air compressor ACP compresses the oxidant gas and supplies it to the fuel cell FC via the intercooler IC and the air shutoff valve ASV.

The intercooler IC exchanges heat between the oxidant gas and a refrigerant such as cooling water that flows through the intercooler IC.

The air shutoff valve ASV blocks the oxidant gas supplied to the fuel cell FC.

The air pressure regulator valve ARV adjusts the pressure and flow rate of the oxidant gas supplied to the fuel cell FC.

The radiator R exchanges heat between the refrigerant, which is heated by the heat generated by the fuel cell, and the outside air.

The fan F increases the amount of heat dissipated by the radiator R. The fuel cell system 1 is also equipped with a bypass flow path P that connects the input and output of the radiator R. This allows the refrigerant output from the fuel cell FC to be supplied to the water pump WP without passing through the radiator R, so that even if the rotation speed of the motor that drives the fan F is increased to increase the amount of heat dissipated by the radiator R, the refrigerant can be prevented from becoming supercooled (overcooled).

The water pump WP supplies the refrigerant cooled by the radiator R to the fuel cell FC via the intercooler IC.

The DCDC converter CNV is provided after the fuel cell FC and supplies the power output from the fuel cell FC to the power storage device B. Of the power output from the DCDC converter CNV, the remaining power after the power consumed by the auxiliary equipment is supplied to the power storage device B.

The power storage device B is provided between the DCDC converter CNV and the load Lo, and supplies power to the load Lo and auxiliary equipment such as the hydrogen circulation pump HP, the air compressor ACP, the fan F, and the water pump WP. The power storage device B may be configured with a capacitor such as a lithium ion capacitor. Generally, among secondary batteries, a capacitor has a relatively small capacity and excellent charge/discharge characteristics, so by configuring the power storage device B with a capacitor, the charge/discharge characteristics of the fuel cell system 1 can be made relatively high.

The control unit 2 is composed of a microcomputer including a CPU that performs logical operations based on programs stored in memory.

During normal power generation control, the control unit 2 also drives various auxiliary devices such as the hydrogen tank valve HTV, injector INJ, hydrogen circulation pump HP, exhaust drain valve EDV, air compressor ACP, air pressure regulating valve ARV, air shutoff valve ASV, fan F, and water pump WP so that the power generated in the fuel cell FC becomes the target power Pt. For example, when the fuel cell FC starts generating power, the control unit 2 turns on the power supply to the motors for driving the various auxiliary devices, and then outputs a command value indicating the target rotation speed of each motor.

In addition, during normal power generation control, the control unit 2 changes the target power Pt according to the charge amount of the storage device B. The charge amount is the ratio [%] of the current capacity of the storage device B to the full charge capacity (charging rate), or the voltage [V] of the storage device B when no current flows through the storage device B.

The control unit 2 may be configured to change the target power Pt in stages according to the charge amount of the storage device B. For example, assume that the charging rate SOC1 < charging rate SOC2 < charging rate SOC3 < charging rate SOC4 < charging rate SOC5 < charging rate SOC6, and the target power Pt1 < target power Pt2. In this case, the control unit 2 sets the target power Pt1 as the target power Pt when the charging rate of the storage device B is decreasing in the range of charging rate SOC3 to charging rate SOC5, sets the target generation power Pt2 as the target power Pt when the charging rate of the storage device B is decreasing in the range of charging rate SOC1 to charging rate SOC3, sets the target power Pt2 as the target power Pt when the charging rate of the storage device B is increasing in the range of charging rate SOC2 to charging rate SOC4, and sets the target power Pt1 as the target power Pt when the charging rate of the storage device B is increasing in the range of charging rate SOC4 to charging rate SOC6.

Here, FIG. 2 is a diagram showing an example of the current and voltage output from the fuel cell FC. Note that the horizontal axis of the two-dimensional coordinate system shown in FIG. 2 indicates the current [A], the vertical axis indicates the voltage [V], and the solid line indicates the correspondence between the current and voltage output from the fuel cell FC.

As shown in FIG. 2, the smaller the current output from the fuel cell FC, the greater the voltage output from the fuel cell FC. In addition, when the voltage output from the fuel cell FC becomes relatively high, the catalyst necessary for the electrochemical reaction is ionized, and the next time the voltage output from the fuel cell FC becomes relatively small, the crystals of the ionized catalyst become larger, which increases the particle size of the catalyst and reduces the surface area of the catalyst, which may cause deterioration of the fuel cell FC.

In the embodiment, the control unit 2 forcibly drives the DCDC converter CNV when the output voltage of the fuel cell FC reaches or exceeds a predetermined voltage Vc, thereby increasing the current flowing from the fuel cell FC to the DCDC converter CNV and lowering the voltage output from the fuel cell FC. This makes it possible to prevent the voltage output from the fuel cell FC from becoming relatively large during idling when the vehicle Ve is temporarily stopped, for example at a traffic light, and the current flowing from the fuel cell system 1 to the load Lo becomes relatively small, thereby preventing the fuel cell FC from deteriorating.

In addition, when the vehicle Ve is traveling downhill, the regenerative power supplied from the vehicle Ve (load Lo) to the fuel cell system 1 is assumed to be relatively large. In addition, when the vehicle Ve is traveling downhill, the driver operates the accelerator of the vehicle Ve so that the speed of the vehicle Ve remains constant, thereby causing the acceleration of the vehicle Ve to be relatively small.

Therefore, when the regenerative power supplied from the vehicle Ve to the fuel cell system 1 is relatively large and the acceleration of the vehicle Ve is relatively small, there is a high possibility that the vehicle Ve is traveling downhill.

When the vehicle Ve is traveling downhill, there is a concern that the supply of regenerative power from the vehicle Ve to the fuel cell system 1 for a relatively long period of time may increase the possibility of the storage device B becoming overcharged.

Therefore, in the embodiment, in the control unit 2, when the regenerative power supplied from the vehicle Ve to the fuel cell system 1 is equal to or greater than a predetermined power and the acceleration of the vehicle Ve is equal to or less than the predetermined acceleration, i.e., when the vehicle Ve is likely traveling downhill and there is a risk that the storage device B will be overcharged, the power generation of the fuel cell FC is stopped, while auxiliary equipment that is not directly involved in the power generation of the fuel cell FC is forcibly driven so that the output voltage of the fuel cell FC does not become relatively high.

The control unit 2 multiplies the voltage output from the vehicle Ve to the fuel cell system 1 by the current flowing from the vehicle Ve to the fuel cell system 1, and determines the regenerative power supplied from the vehicle Ve to the fuel cell system 1. The control unit 2 also receives the speed [km/h] of the vehicle Ve from a driving control unit (not shown) mounted on the vehicle Ve, and determines the amount of change in the speed of the vehicle Ve per unit time as the acceleration of the vehicle Ve. The speed of the vehicle Ve is calculated as (travel motor rotation speed x tire outer diameter x pi) / (gear ratio x reduction ratio). Alternatively, the control unit 2 receives the acceleration of the vehicle Ve calculated by an acceleration sensor from the driving control unit.

In this way, in the control unit 2 of the embodiment, when there is a high possibility that the vehicle Ve is traveling downhill and there is a risk that the storage device B will become overcharged, the power generation of the fuel cell FC is stopped while the auxiliary equipment that is not directly involved in the power generation of the fuel cell FC is driven. This makes it possible to prevent the output of the fuel cell FC from becoming a high potential, and to prevent the fuel cell FC from deteriorating, even if the auxiliary equipment consumes the power supplied from the fuel cell FC so that the storage device B does not become overcharged. In other words, it is possible to prevent the fuel cell FC from deteriorating while preventing the storage device B from becoming overcharged.

When the amount of regenerative power supplied from the vehicle Ve to the fuel cell system 1 is relatively small, the power storage device B is unlikely to become overcharged, and there is no need to stop power generation by the fuel cell FC or operate the auxiliary equipment, so the control unit 2 continues normal power generation control.

In addition, when the regenerative power supplied from the vehicle Ve to the fuel cell system 1 is relatively large, but the acceleration of the vehicle Ve is relatively large, it is highly likely that the regenerative power temporarily becomes relatively large when the vehicle Ve decelerates while traveling on a flat road, and since there is no need to stop the power generation of the fuel cell FC or operate the auxiliary equipment, the control unit 2 continues normal power generation control.

In addition, the control unit 2 increments the counter value when the regenerative power is equal to or greater than the predetermined power and the acceleration of the vehicle Ve is equal to or less than the predetermined acceleration, decrements the counter value when the regenerative power is less than the predetermined power or the acceleration of the vehicle Ve is greater than the predetermined acceleration, and when the counter value is equal to or greater than the threshold C1th (first threshold), determines that the vehicle Ve is traveling downhill and turns on the downhill flag. In addition, when the downhill flag is turned on, the control unit 2 stops the power generation of the fuel cell FC and drives the auxiliary equipment that is not directly involved in the power generation of the fuel cell FC. That is, the control unit 2 increments the counter value when the regenerative power is equal to or greater than the predetermined power and the acceleration of the vehicle Ve is equal to or less than the predetermined acceleration, decrements the counter value when the regenerative power is less than the predetermined power or the acceleration of the vehicle Ve is greater than the predetermined acceleration, and when the counter value is equal to or greater than the threshold C1th, stops the power generation of the fuel cell FC and drives the auxiliary equipment that is not directly involved in the power generation of the fuel cell FC.

This makes it possible to prevent the fuel cell FC from frequently stopping and restarting power generation due to fluctuations in regenerative power and the acceleration of the vehicle Ve, thereby reducing the impact on the running of the vehicle Ve caused by the fuel cell FC frequently stopping and restarting power generation, and preventing the driver of the vehicle Ve from feeling uncomfortable about the running of the vehicle Ve.

The control unit 2 may also be configured to prepare to drive auxiliary equipment that is not directly involved in power generation by the fuel cell FC when the counter value becomes equal to or greater than a threshold C2th (second threshold) that is smaller than the threshold C1th.

As a result, the auxiliary equipment can be driven to consume the power supplied from the fuel cell FC immediately after the counter value reaches or exceeds the threshold value C1th, compared to when preparations to drive the auxiliary equipment are not made before the counter value reaches or exceeds the threshold value C1th, thereby further preventing the storage device B from becoming overcharged.

The control unit 2 may also be configured to stop power generation by the fuel cell FC when the regenerative power is equal to or greater than a predetermined power and when the acceleration of the vehicle Ve is equal to or less than a predetermined acceleration, and then drive one or more of the multiple auxiliary devices according to the charge amount of the power storage device B.

Here, it is assumed that the control unit 2 performs one of the following operational controls 1) to 4) as operational control of the auxiliary equipment when power generation by the fuel cell FC is stopped.

1) Set the motor speed for driving the water pump WP to maximum speed.

2) Set the motor speed for driving the water pump WP and hydrogen circulation pump HP to maximum speed.

3) Set the motors for driving the water pump WP, hydrogen circulation pump HP, and fan F to their maximum rotational speeds.

4) Set the rotation speed of the motors for driving the water pump WP, hydrogen circulation pump HP, and fan F to the maximum, and increase the rotation speed of the motor for driving the air compressor ACP and the specified voltage Vc to avoid high voltage.

When the above operation control 4) is performed, the consumption of the power supplied from the fuel cell FC is the largest, when the above operation control 3) is performed, the consumption of the power supplied from the fuel cell FC is the second largest, when the above operation control 2) is performed, the consumption of the power supplied from the fuel cell FC is the third largest, and when the above operation control 1) is performed, the consumption of the power supplied from the fuel cell FC is the smallest. Also, when the above operation control 1) is performed, the influence on the deterioration of the fuel cell FC is the lowest, when the above operation control 2) is performed, the influence on the deterioration of the fuel cell FC is the second lowest, when the above operation control 3) is performed, the influence on the deterioration of the fuel cell FC is the third lowest, and when the above operation control 4) is performed, the influence on the deterioration of the fuel cell FC is the fourth lowest. Also, the threshold value S1th < threshold value S2th < threshold value S3th < threshold value S4th.

In this case, when the regenerative power is equal to or greater than a predetermined power and the acceleration of the vehicle Ve is equal to or less than a predetermined acceleration, the control unit 2 stops the power generation of the fuel cell FC, and then performs the above-mentioned operation control 1) if the charge amount of the storage device B is equal to or greater than a threshold value S1th, performs the above-mentioned operation control 2) if the charge amount of the storage device B is equal to or greater than a threshold value S2th, performs the above-mentioned operation control 3) if the charge amount of the storage device B is equal to or greater than a threshold value S3th, and performs the above-mentioned operation control 4) if the charge amount of the storage device B is equal to or greater than a threshold value S4th.

As a result, when the fuel cell FC stops generating electricity, if the charge amount of the power storage device B is equal to or greater than the threshold value S1th, the control unit 2 performs the operation control 1), so that the power of the power storage device B can be consumed while minimizing the impact on the deterioration of the fuel cell FC. Also, when the fuel cell FC stops generating electricity, if the charge amount of the power storage device B is equal to or greater than the threshold value S2th, the control unit 2 performs the operation control 2), so that the power of the power storage device B can be consumed while relatively reducing the impact on the deterioration of the fuel cell FC. Also, when the fuel cell FC stops generating electricity, if the charge amount of the power storage device B is equal to or greater than the threshold value S3th, the control unit 2 performs the operation control 3), so that the impact on the deterioration of the fuel cell FC can be suppressed while relatively increasing the amount of power consumed by the power storage device B. Also, when the fuel cell FC stops generating electricity, if the charge amount of the power storage device B is equal to or greater than the threshold value S4th, the control unit 2 performs the operation control 4), so that the impact on the deterioration of the fuel cell FC can be suppressed while maximizing the amount of power consumed by the power storage device B.

In this way, when there is a high possibility that the vehicle Ve is traveling downhill and there is a risk that the storage device B will become overcharged, the operation of the auxiliary equipment can be appropriately controlled according to the charge level of the storage device B, so that the storage device B can be prevented from becoming overcharged while also suppressing deterioration of the fuel cell FC.

Figure 3 is a flowchart showing an example of the operation of the control unit 2 during the downhill flag switching process.

First, if the regenerative power supplied from the vehicle Ve to the fuel cell system 1 is equal to or greater than a predetermined power and if the acceleration of the vehicle Ve is equal to or less than a predetermined acceleration (step S11: Yes), the control unit 2 increments the counter value of the counter (step S12).

Next, if the counter value is equal to or greater than the threshold value C2th (second threshold value) (step S13: Yes), the control unit 2 prepares to drive various auxiliary devices (step S14).

Next, if the counter value is equal to or greater than the threshold value C1th (first threshold value) (step S15: Yes), the control unit 2 sets the counter value to the threshold value C1th, turns on the downhill flag (step S16), and ends the downhill flag switching process.

On the other hand, if the regenerative power supplied from the vehicle Ve to the fuel cell system 1 is less than the predetermined power, or if the acceleration of the vehicle Ve is greater than the predetermined acceleration (step S11: No), the control unit 2 de-increments the counter value of the counter (step S17).

Next, if the counter value is equal to or less than zero (step S18: Yes), the control unit 2 sets the counter value to zero and turns off the downhill flag (step S19), and ends the downhill flag switching process.

The control unit 2 also terminates the downhill flag switching process if the counter value is smaller than the threshold C2th (step S13: No), or if the counter value is smaller than the threshold C1th (step S15: No), or if the counter value is greater than zero (step S18: No).

Figure 4 is a flowchart showing an example of the operation of the control unit 2 during power generation control processing.

First, if the downhill flag is off (step S21: No), the control unit 2 performs normal power generation control (step S22).

On the other hand, if the downhill flag is on (step S21: Yes), the control unit 2 stops power generation by the fuel cell FC (step S23).

Next, when the charge amount of the storage device B becomes equal to or greater than the threshold value S1th (step S24: Yes), the control unit 2 outputs a command value so that the rotation speed of the motor for driving the water pump WP becomes the maximum rotation speed (step S25).

Next, when the charge amount of the power storage device B becomes equal to or greater than the threshold value S2th (step S26: Yes), the control unit 2 outputs a command value so that the rotational speed of the motor for driving the hydrogen circulation pump HP becomes the maximum rotational speed (step S27). Note that in step S27, the control unit 2 continues to output a command value for making the rotational speed of the motor for driving the water pump WP the maximum rotational speed.

Next, when the charge amount of the power storage device B becomes equal to or greater than the threshold value S3th (step S28: Yes), the control unit 2 sets a command value so that the rotation speed of the motor for driving the fan F becomes the maximum rotation speed (step S29). Note that in step S29, the control unit 2 continues to output a command value for setting the rotation speed of the motor for driving the water pump WP and the hydrogen circulation pump HP to the maximum rotation speed.

When the charge amount of the power storage device B becomes equal to or greater than the threshold value S4th (step S30: Yes), the control unit 2 increases the rotation speed of the motor for driving the air compressor ACP and the predetermined voltage Vc for avoiding high potential (step S31). Note that in step S31, the control unit 2 continues to output command values for setting the rotation speed of the motors for driving the water pump WP, the hydrogen circulation pump HP, and the fan F to the maximum rotation speed.

The present invention is not limited to the above-described embodiment, and various improvements and modifications are possible without departing from the spirit of the present invention.

1 Fuel cell system 2 Control unit Ve Vehicle Lo Load FC Fuel cell HT Hydrogen tank HTV Hydrogen tank valve INJ Injector GLS Gas-liquid separator HP Hydrogen circulation pump EDV Exhaust drain valve ACP Air compressor ARV Air pressure regulating valve ASV Air shutoff valve R Radiator F Fan WP Water pump IC Intercooler CNV DCDC converter B Electricity storage device

Claims (5)

A fuel cell system mounted on a vehicle,
A fuel cell;
a power storage device connected between the fuel cell and a load mounted on the vehicle;
a plurality of auxiliary machines driven by power supplied from the fuel cell;
a DC-DC converter that supplies the electric power output from the fuel cell to a load and the plurality of auxiliary machines mounted on the vehicle and supplies the remaining electric power output from the fuel cell to the power storage device;
A control unit that controls power generation by the fuel cell , an operation of the DCDC converter, and an operation of the auxiliary equipment;
Equipped with
the plurality of auxiliary machines are a water pump that supplies a coolant cooled by a radiator to the fuel cell, a hydrogen circulation pump that supplies fuel gas discharged from the fuel cell back to the fuel cell, a fan that increases the amount of heat dissipated by the radiator, and an air compressor that supplies an oxidant gas to the fuel cell;
The control unit forcibly drives the DC-DC converter when the output voltage of the fuel cell becomes equal to or higher than a predetermined voltage for avoiding a high potential,
When regenerative power supplied from the vehicle to the fuel cell system is equal to or greater than a predetermined power and the acceleration of the vehicle is equal to or less than a predetermined acceleration, the control unit stops power generation of the fuel cell, selects at least one auxiliary device to be driven from the water pump, the hydrogen circulation pump, the fan, and the air compressor in accordance with the charge amount of the power storage device, and increases the rotation speed and the predetermined voltage of a motor for driving the selected auxiliary device to be driven.
A fuel cell system comprising: 2. The fuel cell system according to claim 1 ,
The control unit is
When the regenerative power is equal to or greater than the predetermined power and the acceleration is equal to or less than the predetermined acceleration, incrementing a counter value;
If the regenerative power is smaller than the predetermined power or if the acceleration is larger than the predetermined acceleration, the counter value is decremented;
a first threshold value or more, the fuel cell system stops power generation by the fuel cell and drives the auxiliary devices that are not directly involved in power generation by the fuel cell. 3. The fuel cell system according to claim 2 ,
The control unit prepares to drive the auxiliary machinery not directly involved in power generation by the fuel cell when the counter value becomes equal to or greater than a second threshold value that is smaller than the first threshold value. The fuel cell system according to any one of claims 1 to 3 ,
The fuel cell system according to claim 1, wherein the power storage device is a capacitor. 2. The fuel cell system according to claim 1,
When the regenerative power is equal to or greater than the predetermined power and the acceleration is equal to or less than the predetermined acceleration, the control unit, after stopping power generation of the fuel cell, increases the rotation speed of the motor for driving the water pump when the charge amount becomes equal to or greater than a first charge amount, and thereafter, when the charge amount becomes equal to or greater than a second charge amount that is greater than the first charge amount, further increases the rotation speed of the motor for driving the hydrogen circulation pump, and thereafter, when the charge amount becomes equal to or greater than a third charge amount that is greater than the second charge amount, further increases the rotation speed of the motor for driving the fan, and thereafter, when the charge amount becomes equal to or greater than a fourth charge amount that is greater than the third charge amount, further increases the rotation speed of the motor for driving the air compressor.
A fuel cell system comprising:

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