阅读说明：本技术 搭载于车辆的燃料电池系统 (Fuel cell system mounted on vehicle ) 是由 大矢良辅 于 2020-08-04 设计创作，主要内容包括：本发明提供搭载于车辆的燃料电池系统,具备燃料电池、二次电池、包括驱动马达及空气压缩机的负载、燃料电池用转换器、二次电池用转换器、故障检测部、第1状态判定部、反转检测部以及控制部。在二次电池用转换器故障时,控制部进行从二次电池向驱动马达供给电力的跛行行驶控制。对于控制部而言,在不处于第1状态的情况下禁止驱动马达的再生,在处于第1状态的情况下向空气压缩机通电无功电流,在无功电流的通电时检测到空气压缩机的反转的情况下,不进行以后的无功电流的通电。(The invention provides a fuel cell system mounted on a vehicle, comprising a fuel cell, a secondary cell, a load including a drive motor and an air compressor, a converter for the fuel cell, a converter for the secondary cell, a failure detection unit, a1 st state determination unit, a reverse rotation detection unit, and a control unit. When the converter for the secondary battery fails, the control unit performs limp-home running control in which electric power is supplied from the secondary battery to the drive motor. The control unit prohibits the regeneration of the drive motor when not in the 1 st state, and supplies the idle current to the air compressor when in the 1 st state, and does not supply the subsequent idle current when the reverse rotation of the air compressor is detected when the idle current is supplied.)

1. A fuel cell system mounted on a vehicle, comprising:

a fuel cell;

a secondary battery;

a load including a drive motor having a function as a motor for generating a driving force of the vehicle and a function as a generator for generating regenerative electric power, and an air compressor configured to supply oxygen to the fuel cell by rotating in one direction;

a converter for a fuel cell configured to boost electric power from the fuel cell and output the boosted electric power to the load;

a converter for a secondary battery provided between the secondary battery and the load, configured to boost electric power from the secondary battery and output the boosted electric power to the load, and configured to step down electric power from the load and use the stepped-down electric power for charging the secondary battery;

a failure detection unit configured to detect a failure in operation of the converter for a secondary battery;

a1 st state determination unit configured to determine whether or not the vehicle is in a1 st state, the 1 st state being a state in which an actual traveling direction, which is an actual traveling direction of the vehicle, does not coincide with a requested traveling direction assumed from a rotation direction of the drive motor;

a reverse rotation detection unit configured to detect reverse rotation, which is rotation in a direction opposite to the one direction in the air compressor; and

a control unit configured to control the fuel cell, the converter for the fuel cell, and the converter for the secondary cell,

wherein the control unit is configured to:

performing limp-home running control in which, when a failure in operation of the secondary battery converter is detected, the supply of electric power to the load via the fuel cell converter is stopped, the secondary battery converter is brought into an on state, and electric power is supplied from the secondary battery to the drive motor,

in the limp-home running control,

prohibiting regeneration of the drive motor when the vehicle is not in the 1 st state,

consuming regenerative electric power of the drive motor by energizing reactive current to the air compressor with the vehicle in the 1 st state,

when the reverse rotation of the air compressor is detected when a reactive current is supplied to the air compressor, the supply of the reactive current to the air compressor after the detection of the reverse rotation is not performed.

2. The fuel cell system according to claim 1,

the control unit is configured to, when the reverse rotation of the air compressor is not detected in the limp home running control,

stopping the energization of the reactive current when a continuous energization time from the start of the energization of the reactive current to the air compressor reaches a predetermined 1 st time,

when the stop time from the stop of the energization of the reactive current reaches a predetermined 2 nd time, the energization of the reactive current is restarted.

3. The fuel cell system according to claim 1 or 2,

the air compressor is a turbine type air compressor.

Technical Field

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

Background

Japanese patent application laid-open No. 2018-181834 describes a fuel cell system including a fuel cell, a secondary cell, and a boost converter provided on the output side of the fuel cell and the secondary cell, respectively. In this fuel cell system, when a failure occurs in the secondary battery converter, the input side and the output side of the secondary battery converter are turned on, and the fuel cell is controlled to a target voltage calculated based on the step-up ratio of the fuel cell converter and the output voltage of the secondary battery step-up converter, so that electric power is supplied from the fuel cell to a load such as a drive motor.

When the input side and the output side of the secondary battery converter are turned on due to a failure of the secondary battery converter, if the electric power supplied from the fuel cell to the drive motor is excessive electric power, the excessive electric power cannot be stepped down by the secondary battery converter and charged in the secondary battery. Therefore, it is conceivable to stop the supply of electric power from the fuel cell and continue the supply of electric power to the drive motor using the output from the secondary battery. In this case, for example, in a fuel cell vehicle equipped with a regenerative brake that uses regenerative power of a drive motor as braking force, since the regenerative power cannot be charged to the secondary battery, it is conceivable to perform limp home (limp home) on the vehicle and prohibit regeneration using output from the secondary battery. However, if the regeneration is prohibited uniformly, the following may occur.

For example, it is assumed that the operator of the vehicle intends to move the vehicle forward by switching the depression of the accelerator pedal from the brake pedal in a state where the vehicle is stopped on an uphill road by the depression of the brake pedal. In this case, since the vehicle is temporarily moving backward on a slope, the vehicle speed is negative, and the drive motor is set to positive torque by depressing the accelerator pedal, which corresponds to reverse regeneration in four-quadrant operation. However, when the regeneration is prohibited when the converter for the secondary battery fails, the hill start of the vehicle using the regenerative brake becomes difficult. In the fuel cell vehicle, since an air compressor for supplying oxygen to the fuel cell is mounted, it is also conceivable to consume generated power generated by regeneration at the time of starting after a hill stop by supplying reactive current to the air compressor, and start the vehicle on a hill by using a regenerative brake.

In recent years, an air compressor capable of rotating at high speed is employed in a fuel cell vehicle. In such an air compressor, the components such as bearings are more precise than in the conventional art, and for example, if the air compressor is reversed by supplying a reactive current, the air compressor may be broken down. However, so-called secondary failure in which the air compressor fails by supplying a reactive current to the air compressor at the time of hill start in the limp-home running of the fuel cell vehicle has not been considered. Therefore, in a system that performs limp-home running using an output from the secondary battery when the converter for the secondary battery fails, a technique capable of suppressing a secondary failure of the air compressor is required.

Disclosure of Invention

The present disclosure can be implemented as follows.

According to one aspect of the present disclosure, a fuel cell system mounted on a vehicle is provided. The system is provided with: a fuel cell; a secondary battery; a load including a drive motor having a function as a motor for generating a driving force of the vehicle and a function as a generator for generating regenerative electric power, and an air compressor configured to supply oxygen to the fuel cell by rotating in one direction; a converter for a fuel cell configured to boost electric power from the fuel cell and output the boosted electric power to the load; a converter for a secondary battery provided between the secondary battery and the load, configured to boost electric power from the secondary battery and output the boosted electric power to the load, and configured to step down electric power from the load and use the stepped-down electric power for charging the secondary battery; a failure detection unit configured to detect a failure in operation of the converter for a secondary battery; a1 st state determination unit configured to determine whether or not the vehicle is in a1 st state, the 1 st state being a state in which an actual traveling direction, which is an actual traveling direction of the vehicle, does not coincide with a requested traveling direction assumed based on a rotation direction of the drive motor; a reverse rotation detection unit configured to detect reverse rotation, which is rotation in a direction opposite to the one direction in the air compressor; and a control unit configured to control the fuel cell, the converter for the fuel cell, and the converter for the secondary cell. The control unit is configured to: in the limp-home running control, when a failure in operation of the secondary battery converter is detected, the power supply to the load via the fuel cell converter is stopped, the secondary battery converter is brought into an on state, and power is supplied from the secondary battery to the drive motor, and in the limp-home running control, when the vehicle is not in the 1 st state, regeneration of the drive motor is prohibited, when the vehicle is in the 1 st state, the regenerative power of the drive motor is consumed by supplying reactive current to the air compressor, and when the reverse rotation of the air compressor is detected when reactive current is supplied to the air compressor, the supply of reactive current to the air compressor after the detection of the reverse rotation is not performed. According to this aspect, in the limp-home running control when the converter for the secondary battery fails, when the state 1 is established, the idle current is supplied to the air compressor to consume the regenerative electric power, the braking force generated by the regeneration is obtained to suppress the backward movement of the vehicle, and the vehicle can be run in the requested running direction. When the reverse rotation of the air compressor is detected, the subsequent reactive current is not supplied to the air compressor, so that it is possible to suppress a so-called secondary failure in which the air compressor fails in addition to the failure of the secondary battery converter.

In the above aspect, the control unit may be configured to stop the energization of the reactive current when a continuous energization time from a start of the energization of the reactive current to the air compressor reaches a predetermined 1 st time and to restart the energization of the reactive current when a stop time from the stop of the energization of the reactive current reaches a predetermined 2 nd time, in a case where the reverse rotation of the air compressor is not detected in the limp-home running control. According to this aspect, since overheating of the air compressor can be suppressed, secondary failure of the air compressor can be suppressed in addition to failure of the converter for the secondary battery.

In the above aspect, the air compressor may be a turbine air compressor. According to this aspect, occurrence of a secondary failure in the turbine air compressor can be suppressed.

The present disclosure can be implemented in various ways, for example, in a fuel cell vehicle, a method of controlling a fuel cell system mounted on the vehicle, a computer program for implementing the control method, a non-transitory storage medium (non-transitory storage medium) on which the computer program is recorded, and the like.

Drawings

Features, advantages, technical and industrial significance of exemplary embodiments of the present invention will be described below with reference to the accompanying drawings, in which like reference numerals represent like elements, and wherein:

fig. 1 is a diagram showing a schematic configuration of a vehicle equipped with a fuel cell system.

Fig. 2 is a process diagram showing the limp home running control in embodiment 1.

Fig. 3 is a process diagram showing the limp home running control in embodiment 2.

Detailed Description

A. Embodiment 1:

A1. structure of fuel cell system

Fig. 1 is a schematic configuration diagram showing a fuel cell system 100 according to an embodiment of the present invention. The fuel cell system 100 is equipped with a vehicle 200. As shown in fig. 1, the fuel cell system 100 includes a fuel cell 10 and a secondary battery 50 as power supply sources to a load, a fuel cell converter 20 (hereinafter, also referred to as "FDC 20"), an FC relay circuit 30, a power control unit 40 (hereinafter, also referred to as "PCU 40") including a secondary battery converter 45 (hereinafter, also referred to as "BDC 45"), a control device 60, a secondary battery relay circuit 70, an auxiliary device 90, an auxiliary battery 91, an auxiliary inverter 28, an air conditioner 29, and an air compressor MG1 and a drive motor MG2 as loads.

The fuel cell 10 is a cell that generates electric power by reacting hydrogen and oxygen as reaction gases. The vehicle 200 on which the fuel cell system 100 is mounted has a hydrogen tank (not shown) that stores hydrogen (fuel gas) as a reaction gas, and hydrogen is supplied from the hydrogen tank to the fuel cell 10. The air in the atmosphere is compressed by the rotation of the air compressor MG1 in one direction, and the air containing oxygen (oxidizing gas) as a reaction gas is supplied from the air compressor MG1 to the fuel cell 10. The air compressor MG1 in the present embodiment is a turbo type air compressor. In the air compressor MG1 of the present embodiment, cooling of components such as bearings is achieved by circulating oil. In other embodiments, the air compressor MG1 is not limited to a turbine type, and may be a roots type.

The FDC20 boosts the output voltage of the fuel cell 10 to the drive voltage of the air compressor MG1 and the drive motor MG 2. A voltage sensor 12 that detects the output voltage of the fuel cell 10 is provided between the FDC20 and the fuel cell 10. The FC relay circuit 30 switches between a connected state of electrically connecting the FDC20 with the PCU40 and a disconnected state of electrically disconnecting the FDC20 from the PCU 40. The FC relay circuit 30 is disposed between the FDC20 and the PCU 40.

The drive motor MG2 is a motor driven by electric power supplied from the fuel cell 10 and the secondary battery 50, and is connected in parallel to the air compressor MG 1. The drive motor MG2 operates as a motor or a generator. When operating as a motor, drive motor MG2 drives the drive wheels of vehicle 200 using electric power supplied from fuel cell 10 and secondary battery 50. The drive motor MG2 generates regenerative electric power when it operates as a generator to obtain a braking force.

The auxiliary machinery 90 consumes the electric power generated by the fuel cell 10. The auxiliary 90 includes a hydrogen pump 25, a cooling water pump 26, auxiliary inverters 23, 24, and a water heater 27. The hydrogen pump 25 returns the hydrogen off-gas discharged from the fuel cell 10 to the fuel cell 10. The cooling water pump 26 circulates cooling water used by the fuel cell 10. The auxiliary inverters 23 and 24 convert the direct current into a three-phase alternating current, supply the three-phase alternating current to the hydrogen pump 25 and the cooling water pump 26, and perform drive control.

The secondary battery 50 outputs electric power for driving the air compressor MG1 and the drive motor MG 2. For example, a lithium ion battery or a nickel hydride battery can be used as the secondary battery 50. The secondary battery 50 can be charged with the electric power generated by the fuel cell 10 and the regenerative electric power from the drive motor MG 2. The secondary battery relay circuit 70 switches between a connection state for electrically connecting the secondary battery 50 to the PCU40 and a disconnection state for electrically disconnecting the secondary battery 50 from the PCU 40. The output voltage from the secondary battery 50 is detected by a voltage sensor 44 connected to the secondary battery relay circuit 70.

The auxiliary battery 91 is used as a power supply for low-voltage auxiliary machines of the vehicle. The auxiliary battery 91 is electrically connected between the secondary battery relay circuit 70 and the BDC45 via the DC/DC converter 92. The auxiliary battery 91 is supplied with electric power stepped down by the DC/DC converter 92.

The PCU40 controls electric power supplied to the air compressor MG1 and the drive motor MG2 based on a control signal sent from the control device 60. The PCU40 has a capacitor 41, an inverter 48, and a BDC 45.

The inverter 48 is connected to an air compressor MG1 and a drive motor MG2 as loads. When the drive motor MG2 operates as a motor, the inverter 48 converts dc power supplied from the fuel cell 10 and the secondary battery 50 into three-phase ac power. When the drive motor MG2 operates as a generator, the inverter 48 converts the three-phase alternating current power, which is the regenerative power output from the drive motor MG2, into direct current power.

The BDC45 is a buck-boost converter that steps down the output voltage from the FDC20 to charge the secondary battery 50 and steps up the output voltage from the secondary battery 50 to the drive voltage of the air compressor MG1 and the drive motor MG 2. In the present embodiment, when the failure detection unit 62 described later detects that a failure has occurred in the operation of the BDC45, the BDC45 directly electrically couples the input side and the output side of the BDC45 to switch to the on state in which the voltage boosting operation and the voltage dropping operation are restricted although current can be supplied. In the on state, the voltage between the BDC45 and the inverter 48 becomes the voltage of the secondary battery 50.

In the present embodiment, the fuel cell system 100 further includes an accelerator pedal sensor 101, a brake pedal sensor 102, a shift position sensor 103, a vehicle speed sensor 104, a rotation sensor 105, and a current sensor 106. The accelerator pedal sensor 101 detects a step amount of an accelerator pedal 201 of the vehicle 200. The brake pedal sensor 102 detects a depression amount of a brake pedal 202 of the vehicle 200. The stepping amount can also be referred to as "opening degree". The shift position sensor 103 detects a shift position of the shift device 203 of the vehicle 200. The gear includes a position indicating a forward request from the operator to the vehicle 200 and a position indicating a reverse request. The vehicle speed sensor 104 detects a vehicle speed from the rotation speed of the drive shaft of the vehicle 200. The vehicle speed sensor 104 outputs a positive vehicle speed when the vehicle 200 travels in the forward direction, and outputs a negative vehicle speed when the vehicle 200 travels in the backward direction. The rotation sensor 105 detects the rotation direction of the air compressor MG 1. In the present embodiment, the rotation sensor 105 is a resolver that detects the rotation speed of the air compressor MG 1. The current sensor 106 detects a value of a current flowing in the air compressor MG 1.

Control device 60 is configured as an ECU including a CPU, a memory, and an input/output interface. The CPU of the control device 60 expands and executes the programs stored in the memory to function as the control unit 61, the failure detection unit 62, the 1 st state determination unit 63, and the inversion detection unit 64. The measurement values of the sensors are input to the control device 60.

The failure detection unit 62 detects a failure in the operation of the BDC 45. The failure of the operation of the BDC45 indicates a state in which it is difficult for the fuel cell system 100 to normally perform the operation of either the voltage increase or the voltage decrease by the BDC 45. For example, the failure detection unit 62 can detect a failure of the BDC45 when an overvoltage at the BDC45 is detected based on the measurement values of the voltage sensors 42 and 44 or when an overheat state at a predetermined reference temperature or higher is detected by a temperature sensor, not shown, provided at the BDC 45.

The 1 st state determination unit 63 determines whether or not the state of the vehicle 200 is the 1 st state. The 1 st state is a state in which the actual traveling direction, which is the actual traveling direction of vehicle 200, does not coincide with the requested traveling direction assumed from the rotation direction of drive motor MG 2. In the present embodiment, the 1 st state determination unit 63 determines whether or not the state is the 1 st state using the input results of the accelerator pedal sensor 101, the shift position sensor 103, and the vehicle speed sensor 104, which will be described in detail later.

The reverse rotation detection unit 64 detects the rotation direction of the air compressor MG1 using the input result from the rotation sensor 105 provided in the air compressor MG 1. When the air compressor MG1 rotates in the direction opposite to the one direction in which oxygen is supplied to the fuel cell 10, the reverse rotation detection unit 64 detects that the air compressor MG1 is reversing.

The control unit 61 controls the operation of each unit in the fuel cell system 100 based on the signals input from the sensors. For example, the control unit 61 controls the inverter 48 to cause the drive motor MG2 to realize a function of generating a drive force by electric power from at least one of the fuel cell 10 and the secondary battery 50 and a function as a generator for generating regenerative electric power. When the failure of the BDC45 is detected, the control unit 61 performs limp home control in which the supply of electric power to the load from the fuel cell 10 via the FDC30 is stopped, and the electric power is supplied from the secondary battery 50 to the drive motor MG2 with the BDC45 being in the on state.

A2. With respect to the 1 st state

The vehicle 200 may be stopped on an uphill road by depression of the brake pedal 202, and may be expected to advance from the shift position of the shift device 203 to a forward movement request state by depression of the accelerator pedal 201. The vehicle 200 may slide down backward and the vehicle speed may be negative before the operator of the vehicle 200 switches to step on the accelerator pedal 201 from the brake pedal 202. When the accelerator pedal 201 is depressed in a state where a slip-down occurs, the torque requested of the drive motor MG2 is positive and the drive motor MG2 is positive, but since the vehicle speed is negative, the drive motor MG2 can perform regeneration corresponding to reverse rotation regeneration in four-quadrant operation. This state is a state in which the actual traveling direction, which is the actual traveling direction of vehicle 200, does not coincide with the requested traveling direction assumed from the rotation direction of drive motor MG 2.

Similarly, the vehicle 200 may be stopped on a downhill by depression of the brake pedal 202, and may be intended to be retracted from the shift position of the shift device 203 to a reverse request state by depression of the accelerator pedal 201. The vehicle 200 may slide down forward and the vehicle speed may be positive before the operator of the vehicle 200 switches to step on the accelerator pedal 201 from the brake pedal 202. When the accelerator pedal 201 is depressed in a state where a slip-down occurs, the torque requested of the drive motor MG2 is negative and the drive motor MG2 rotates in the reverse direction, but since the vehicle speed is positive, the drive motor MG2 can perform regeneration corresponding to the normal rotation regeneration in the four-quadrant operation. This state is also a state in which the actual traveling direction of the vehicle 200 does not coincide with the requested traveling direction. Here, "the vehicle 200 rolls down" means that the vehicle 200 travels in a direction opposite to the requested travel direction on a slope.

The 1 st state determination unit 63 determines that the vehicle 200 is in the 1 st state when the vehicle speed is negative and the shift sensor 103 detects a forward travel request and the accelerator pedal 201 is depressed, or when the vehicle speed is positive and the shift sensor 103 detects a reverse travel request and the accelerator pedal 201 is depressed. The 1 st state is a state in which the actual traveling direction of the vehicle 200 indicated by the vehicle speed sensor 104 is different from the requested traveling direction indicated by the shift position sensor 103, and the accelerator pedal 201 is depressed, and it can be determined that the vehicle is going to transition to a state in which both directions are aligned. The 1 st state is also a state in which the drive motor MG2 can perform regeneration if there is a charging target or a consumption target of the regenerative electric power.

The control unit 61 varies the control of the fuel cell system 100 depending on whether or not the vehicle 200 is in the 1 st state in the limp home running control described above.

A3. Limp-home driving control

Fig. 2 is a diagram illustrating a step of the limp home running control in embodiment 1. When the failure of the BDC45 is detected by the failure detection unit 62, the control unit 61 repeatedly executes the limp home running control. In the limp home running control, the 1 st state determination unit 63 sequentially determines whether or not the vehicle 200 is in the 1 st state.

In step S10, the control unit 61 stops the power generation of the fuel cell 10 to stop the supply of electric power from the fuel cell 10 to the load, and brings the input side and the output side of the BDC45 into conduction. The reason why the supply of electric power from the fuel cell 10 is stopped is that the excess electric power among the electric power supplied from the fuel cell 10 to the air compressor MG1 cannot be stepped down through the BDC45 to be charged to the secondary battery 50. By stopping the supply of electric power from the fuel cell 10, it is possible to suppress the capacitor 41 from malfunctioning due to the excessive electric power that cannot be output to the secondary battery 50. When the supply of electric power from the fuel cell 10 has been stopped and the input side and the output side of the BDC45 are on due to the execution of the process shown in fig. 2, the control unit 61 skips the process of step S10.

If the state of vehicle 200 is not in state 1 in step S20 (no in step S20), control unit 61 prohibits regeneration of drive motor MG2 in step S30, and returns the process to step S20.

When the vehicle 200 is in the 1 st state (yes in step S20), in step S40, the control unit 61 first uses the output from the secondary battery 50 to supply a reactive current to the air compressor MG 1. The reactive current value is obtained in advance through experiments and simulations based on a current value that can supply current to the air compressor MG1 and a braking force requested at the time of hill start.

In step S50, the reverse rotation detector 64 detects the rotation direction of the air compressor MG1 using the input result from the rotation sensor 105 provided in the air compressor MG 1. Steps S40 and S50 are performed to check whether or not the air compressor MG1 is reversely rotated by temporarily flowing a reactive current to the air compressor MG1 by the output from the secondary battery 50. Rotation of the air compressor MG1 when the reactive current is supplied may be caused by assembly errors of the components constituting the air compressor MG1, or the like.

When the rotation speed of the air compressor MG1 is zero, or when the air compressor MG1 is rotating in the direction in which oxygen is being delivered to the fuel cell 10 (no in step S50), the control unit 61 advances the process to step S60, stops the supply of electric power from the secondary battery 50, and allows regeneration of the drive motor MG 2. In step S60, the control unit 61 outputs a torque corresponding to the reactive current energized in step S40 from the drive motor MG2 using the input result from the current sensor 106 provided in the air compressor MG 1. The controller 61 supplies the air compressor MG1 with a reactive current corresponding to the amount of regenerative power of the drive motor MG2 to consume the regenerative power of the drive motor MG 2. In this way, the vehicle 200 travels in the requested travel direction by suppressing the slip-down at the time of hill start based on the regenerative braking force.

In step S90, when the vehicle 200 is in the 1 st state (step S90: yes), the control unit 61 returns the process to step S60. If the negative determination at step S90 is made, the vehicle 200 is in the hill start completion state. If the state is not the 1 st state (no in step S90), the control unit 61 ends the present processing routine.

On the other hand, when it is detected in step S50 that the air compressor MG1 is in reverse rotation (yes in step S50), the control unit 61 advances the process to step S70 to stop the supply of the reactive current to the air compressor MG1 and prohibit the supply of the subsequent reactive current. However, when the energization of the reactive current is prohibited in step S70, even if the vehicle 200 becomes the 1 st state again after the end of the current hill start, the control unit 61 does not execute the processing of step S40 and thereafter, and does not consume the regenerative power of the drive motor MG2 due to the energization of the reactive current to the air compressor MG 1. When the energization of the reactive current is prohibited in step S70, for example, a brake control device, not shown, provided in vehicle 200 may brake each wheel to perform hill start assist control for temporarily holding the braking function on a slope. This suppresses the slip-down at the time of hill start, and the vehicle 200 travels in the requested travel direction.

According to this aspect, in the limp-home running control when the secondary battery converter 45 fails, when the vehicle 200 is in the 1 st state, the reactive current is supplied to the air compressor MG1 to consume the regenerative power for driving the motor MG2, and the braking force by the regeneration is obtained to suppress the backward movement of the vehicle 200, thereby enabling the vehicle 200 to run in the requested running direction. Further, when the reverse rotation of the air compressor MG1 is detected, the energization of the reactive current after the detection of the reverse rotation is not performed, so that it is possible to suppress a so-called secondary failure in which the air compressor MG1 also fails in addition to the failure of the secondary battery converter 45. The failure of the air compressor MG1 is, for example, a failure of a bearing due to a reverse rotation of a bearing provided in the air compressor MG 1.

B. Embodiment 2

Fig. 3 is a diagram illustrating a step of the limp home running control in embodiment 2. Embodiment 2 is different from embodiment 1 in that: steps S80, S82, S84, and S86 are provided between step S60 and step S90 in fig. 2 of embodiment 1. The configurations of the fuel cell system 100 and the vehicle 200 according to embodiment 2 and other steps in the limp home running control are the same, and therefore, the description thereof is omitted.

After the idle current is supplied to the air compressor MG1 in step S60, the control unit 61 determines whether or not the continuous supply time from the start of the supply of the idle current to the air compressor MG1 is equal to or longer than a predetermined 1 st time T1 in step S80. The continuous energization time is, for example, an elapsed time from energization of the reactive current in step S40. The 1 st time T1 is obtained in advance through experiments and simulations using the relationship between the energization time of the reactive current, the temperature of the air compressor MG1, and the temperature range in which the performance degradation of the air compressor MG1 can be suppressed. The 1 st time T1 may be, for example, 5 seconds.

If the continuous energization time is shorter than the 1 st time T1 (no in step S80), the control section 61 advances the process to step S90.

When the continuous energization time is not less than the 1 st time T1 (step S80: yes), in step S82, the controller 61 stops energization of the idle current to the air compressor MG 1. The negative determination at step S80 is, for example, a case where the amount of depression of the accelerator pedal 201 is extremely small compared to the amount of depression assumed at the time of hill start. While the energization of the reactive current is stopped, the control unit 61 may notify a display device, a sound device, or the like, not shown, mounted on the vehicle 200 of information urging the brake pedal 202 to be depressed. Alternatively, a brake control device, not shown, provided in the vehicle 200 may brake each wheel during the idle current stop period, and temporarily maintain the braking function on the slope.

In step S84, the control unit 61 determines whether or not the time (continuous stop time) from the stop of the reactive current is equal to or longer than a predetermined 2 nd time T2. The 2 nd time T2 is obtained in advance through experiments and simulations using the relationship between the energization stop time of the reactive current after the continuous energization time is not less than the 1 st time T1, the temperature of the air compressor MG1, and the temperature range in which the performance degradation of the air compressor MG1 can be suppressed. The 2 nd time T2 is, for example, 10 seconds or longer or 15 seconds or longer.

When the continuous stop time is shorter than the 2 nd time T2 (no in step S84), the control unit 61 returns the process to step S82 to continue the stop of the reactive current. When the continuous stop time is equal to or longer than the 2 nd time T2 (yes in step S84), the control unit 61 advances the process to step S86 to restart the energization of the reactive current, and executes the processes after step S60 again.

According to this aspect, since overheating of the air compressor MG1 can be suppressed, it is possible to suppress occurrence of a secondary failure due to overheating of the air compressor MG1 in addition to failure of the secondary battery converter 45.

C. Other embodiments

In the above embodiment, the control unit 61 supplies the idle current to the air compressor MG1 temporarily by the output from the secondary battery 50, and in step S50 (fig. 2 and 3), it is acquired from the inversion detection unit 64 whether or not the air compressor MG1 is inverted, and when the air compressor MG1 is inverted, the supply of the idle current thereafter is prohibited. Alternatively, the control unit 61 may sequentially acquire whether or not the air compressor MG1 is reversed from the reversal detection unit 64 after the idle current is supplied to the air compressor MG1 by the regenerative electric power in step S60, and prohibit the supply of the idle current after the reversal when the air compressor MG1 is reversed (step S50 and step S70).

In the above embodiment, the 1 st state determination unit 63 determines whether or not the state is the 1 st state based on the detection results of the accelerator pedal sensor 101, the shift position sensor 103, and the vehicle speed sensor 104. On the other hand, for example, the 1 st state determining unit 63 may determine that the vehicle 200 is in the 1 st state when it is detected that the vehicle 200 is on a slope and a state in which regeneration during four-quadrant operation is occurring is detected by an acceleration sensor, not shown, provided in the vehicle 200 or a position sensor that measures the position of the vehicle 200. For example, the 1 st state determining portion 63 may determine that the vehicle 200 is in the 1 st state when the current position of the vehicle 200 is a slope, the output torque of the drive motor MG2 is positive, and the rotation speed of the drive motor MG2 per predetermined time is negative.

The present disclosure is not limited to the above-described embodiments, and can be implemented in various configurations without departing from the scope of the present disclosure. For example, in order to solve a part or all of the above-described problems or to achieve a part or all of the above-described effects, technical features in the embodiment and other embodiments corresponding to technical features in the respective embodiments described in the section of the summary of the invention may be appropriately replaced or combined. In addition, as long as the technical features are not described as essential technical features in the present specification, the technical features can be appropriately deleted.