阅读说明：本技术 燃料电池系统 (Fuel cell system ) 是由 难波良一 松尾润一 常川洋之 于 2021-05-27 设计创作，主要内容包括：本发明涉及燃料电池系统,抑制在迅速暖机运中蓄电池劣化这一情况。控制装置(200)具备：供给流量控制部,控制向燃料电池(10)供给的氧化剂气体的供给流量；和发电实施部,实施发电损耗大于通常发电的低效率发电。在低效率发电的实施中,当搭载燃料电池系统(100)的搭载体的状态为第1模式时,供给流量控制部以伴随着发电损耗的燃料电池(10)的发热量成为第1发热量的方式控制氧化剂气体的供给流量,当搭载体的状态为燃料电池(10)的发电电力比第1模式容易变动的第2模式时,供给流量控制部以发热量成为小于第1发热量的第2发热量的方式控制氧化剂气体的供给流量。(The invention relates to a fuel cell system, which can restrain the deterioration of a storage battery in rapid warm-up. A control device (200) is provided with: a supply flow rate control unit that controls the supply flow rate of the oxidizing gas supplied to the fuel cell (10); and a power generation implementation unit for implementing low-efficiency power generation with power generation loss larger than that of normal power generation. In the implementation of low-efficiency power generation, when the state of a carrier on which a fuel cell system (100) is mounted is a1 st mode, a supply flow rate control unit controls the supply flow rate of an oxidizing gas so that the amount of heat generated by a fuel cell (10) due to power generation loss becomes a1 st amount of heat, and when the state of the carrier is a 2 nd mode in which the power generated by the fuel cell (10) is more likely to vary than the 1 st mode, the supply flow rate control unit controls the supply flow rate of the oxidizing gas so that the amount of heat generated becomes a 2 nd amount of heat that is less than the 1 st amount of heat.)

1. A fuel cell system is provided with:

a fuel cell that generates electric power by an electrochemical reaction of a fuel gas and an oxidant gas;

a secondary battery that is charged with surplus power at the time of power generation by the fuel cell and discharges insufficient power; and

a control device for controlling the operation of the motor,

wherein the content of the first and second substances,

the control device is provided with:

a supply flow rate control unit that controls a supply flow rate of the oxidizing gas supplied to the fuel cell; and

a power generation unit for generating power at a lower efficiency than the normal power generation,

in the low-efficiency power generation, when a state in which a carrier of the fuel cell system is mounted is a1 st mode, the supply flow rate control unit controls the supply flow rate of the oxidizing gas so that a heat generation amount of the fuel cell associated with the power generation loss becomes a1 st heat generation amount,

in the low-efficiency power generation, when the carrier is in a 2 nd mode in which the generated power of the fuel cell is more likely to vary than in the 1 st mode, the supply flow rate control unit controls the supply flow rate of the oxidizing gas so that the generated heat amount becomes a 2 nd generated heat amount smaller than the 1 st generated heat amount.

2. The fuel cell system according to claim 1,

the supply flow rate control unit controls the supply flow rate of the oxidizing gas so that the heat generation amount in the 2 nd mode becomes a 3 rd heat generation amount smaller than a 2 nd heat generation amount, based on at least one of allowable charge power or allowable discharge power of the secondary battery determined according to a state of the secondary battery.

3. The fuel cell system according to claim 2,

when the allowable charging power is smaller than a predetermined charging-side threshold, the supply flow rate control unit controls the supply flow rate of the oxidizing gas so that the amount of heat generation in the 2 nd mode becomes the 3 rd amount of heat generation.

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

when the allowable discharge power is smaller than a predetermined discharge-side threshold, the supply flow rate control unit controls the supply flow rate of the oxidizing gas so that the amount of heat generation in the 2 nd mode becomes the 3 rd amount of heat generation.

5. The fuel cell system according to claim 2,

when the carrier is in the 2 nd mode, the supply flow rate control unit controls the supply flow rate of the oxidizing gas such that the generated heat amount becomes the 3 rd generated heat amount if the allowable charging power is smaller than a predetermined 2 nd charging-side threshold smaller than a predetermined 1 st charging-side threshold or the allowable discharging power is smaller than a predetermined 2 nd discharging-side threshold smaller than a predetermined 1 st discharging-side threshold, and controls the supply flow rate of the oxidizing gas such that the generated heat amount becomes the 2 nd generated heat amount if the allowable charging power is equal to or greater than the 1 st charging-side threshold and the allowable discharging power is equal to or greater than the 1 st discharging-side threshold.

6. The fuel cell system according to any one of claims 1 to 5,

the carrying body is a vehicle,

the 1 st mode is a state in which a parking range is selected as a shift range of the vehicle,

the 2 nd mode is a state in which a forward gear or a reverse gear is selected as the shift gear.

Technical Field

The present invention relates to a fuel cell system.

Background

Patent document 1 discloses, as a conventional fuel cell system, a fuel cell system including: by performing low-efficiency power generation in which the power generation loss is larger than that in normal power generation, the self-heating value of the fuel cell is increased, and rapid warm-up operation for rapidly warming up the fuel cell is performed.

Patent document 1: japanese patent laid-open No. 2008-269813

In the low-efficiency power generation, since the concentration overvoltage is increased to increase the power generation loss, the supply flow rate of the oxidizing gas to the fuel cell is smaller than that in the normal power generation if the generated power is the same. That is, the target value of the air stoichiometric ratio (the ratio of the supply flow rate of the oxidant gas to be actually supplied to the supply flow rate of the oxidant gas that is minimally required to generate the target generated power) set at the time of low-efficiency power generation is smaller than the target value of the air stoichiometric ratio set at the time of normal power generation. In the case of low-efficiency power generation performed in a state where the air stoichiometric ratio is reduced from that in the case of normal power generation, the voltage fluctuation range of the fuel cell tends to be larger than that in the case of normal power generation when the air stoichiometric ratio deviates from the target value.

Here, at the time of transition in which the target generated power is changed, the air stoichiometric ratio is deviated from the post-transition target value until the supply flow rate of the oxidizing gas is controlled to the post-transition target flow rate. Therefore, during the low-efficiency power generation, the actual voltage of the fuel cell tends to greatly deviate from the target voltage during the transient period, and as a result, the actual generated power tends to greatly deviate from the target generated power.

If the actual generated power is larger than the target generated power, the surplus power at that time is charged in the battery. On the other hand, if the actual generated power is smaller than the target generated power, the insufficient power at that time is output from the battery. Therefore, if the deviation of the actual generated power from the target generated power becomes large, the battery may be in an overcharged state or an overdischarged state, and the battery may be deteriorated.

In this way, when the power generation is performed at a low efficiency, the actual generated power tends to deviate significantly from the target generated power at the time of transition, and therefore the battery may be in an overcharged state or an overdischarged state, and the battery may be deteriorated.

Disclosure of Invention

The present invention has been made in view of the above problems, and an object of the present invention is to suppress deterioration of a battery due to an overcharged state or an overdischarged state of the battery during a rapid warm-up operation in which low-efficiency power generation is performed.

In order to solve the above problem, a fuel cell system according to an aspect of the present invention includes: a fuel cell that generates electric power by an electrochemical reaction of a fuel gas and an oxidant gas; a secondary battery that is charged with surplus power at the time of power generation by the fuel cell and discharges insufficient power; and a control device. The control device is provided with: a supply flow rate control unit that controls a supply flow rate of the oxidizing gas supplied to the fuel cell; and a power generation implementation unit for implementing low-efficiency power generation with power generation loss larger than that of normal power generation. In the low-efficiency power generation, the supply flow rate control unit controls the supply flow rate of the oxidizing gas so that the amount of heat generated by the fuel cell due to power generation loss becomes the 1 st amount of heat when the state of the carrier on which the fuel cell system is mounted is the 1 st mode, and in the low-efficiency power generation, the supply flow rate control unit controls the supply flow rate of the oxidizing gas so that the amount of heat generated becomes the 2 nd amount of heat smaller than the 1 st amount of heat when the state of the carrier on which the fuel cell system is mounted is the 2 nd mode in which the power generation of the fuel cell is more likely to vary than the 1 st mode.

According to this aspect of the present invention, when the state of the carrier is in the 2 nd mode in which the generated power of the fuel cell is likely to fluctuate, the power generation loss (the amount of heat generation) is reduced, and therefore the air stoichiometric ratio is relatively increased. Therefore, at the time of transition, the actual generated power can be suppressed from deviating from the target generated power, and therefore, in the rapid warm-up operation in which the low-efficiency power generation is performed, the battery can be suppressed from being in an overcharged state or an overdischarged state, and the battery can be prevented from being deteriorated.

Drawings

Fig. 1 is a schematic configuration diagram of a fuel cell system according to an embodiment of the present invention.

Fig. 2 is a graph showing the reference IV characteristic of the fuel cell stack when the FC temperature is a certain temperature.

Fig. 3 is a diagram illustrating a relationship between the air stoichiometric ratio and an oxygen concentration overvoltage which is a factor of power generation loss.

Fig. 4 is a graph showing the change in FC voltage when the air stoichiometric ratio is changed while maintaining the FC current constant.

Fig. 5 is a flowchart illustrating control of the FC air supply amount in the rapid warm-up operation according to the embodiment of the present invention.

Fig. 6 is a flowchart for explaining the setting process of the target heating value in detail.

Fig. 7 is an IV characteristic map depicting an equivalent power line and an equivalent heat generation line for calculating the rapid warming operation point X2.

Fig. 8 is a diagram for explaining a method of calculating the rapid warming operation point X2.

Fig. 9 is a reference IV characteristic map for calculating the reference FC voltage.

Fig. 10 is a map showing the relationship between the air stoichiometric ratio (stoichiometric amount of air) and the oxygen concentration overvoltage for calculating the reference air stoichiometric ratio.

Fig. 11 is a flowchart for explaining the details of the process of setting the target calorific value according to the other embodiment of the present invention.

Description of reference numerals:

10 … fuel cell stack (fuel cell); 53 … storage battery (secondary battery); 100 … fuel cell system; 200 … electronic control unit (control device).

Detailed Description

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the following description, the same components are denoted by the same reference numerals.

Fig. 1 is a schematic configuration diagram of a fuel cell system 100 according to an embodiment of the present invention mounted on a vehicle.

The fuel cell system 100 includes: a fuel cell stack 10; a hydrogen supply device 20 for supplying hydrogen as an anode gas (fuel gas) to the fuel cell stack 10; an air supply device 30 for supplying air as a cathode gas (oxidant gas) to the fuel cell stack 10; an electrical load unit 50 electrically connected to an output terminal of the fuel cell stack 10; and an electronic control unit 200 for collectively controlling various control components of the fuel cell system 100.

The fuel cell stack 10 is a member in which a plurality of fuel cell single cells (hereinafter simply referred to as "single cells") are stacked one on another along a stacking direction and the single cells are electrically connected in series. Each single cell includes mea (membrane Electrode assembly).

The MEA is a member in which an anode electrode is formed on one surface of a proton-conductive ion exchange membrane (hereinafter referred to as an "electrolyte membrane") made of a solid polymer material, and a cathode electrode is formed on the other surface thereof, and these are integrated. When power generation is performed by the fuel cell stack 10, the following electrochemical reactions occur at the anode and cathode electrodes.

Anode electrode: 2H₂→4H⁺+4e^－…(1)

Cathode electrode: 4H⁺+4e^－+O₂→2H₂O…(2)

Each of the anode and cathode electrodes includes a catalyst layer in which a catalyst is supported on a porous carbon material, and each catalyst layer includes platinum as a catalyst for promoting an electrochemical reaction between hydrogen and oxygen (a hydrogen oxidation reaction of formula (1) and an oxygen reduction reaction of formula (2)). Further, the MEA may further include an anode gas diffusion layer and a cathode gas diffusion layer on both outer sides thereof.

The hydrogen supply device 20 includes a hydrogen supply pipe 21, a high-pressure hydrogen tank 22 as a hydrogen source, a hydrogen supply control unit 23, an anode off-gas pipe 24, a gas-liquid separator 25, a hydrogen return pipe 26, a hydrogen circulation pump 27, a purge pipe 28, and a purge control valve 29.

The hydrogen supply pipe 21 is a pipe through which hydrogen supplied to the fuel cell stack 10 flows, and has one end connected to the high-pressure hydrogen tank 22 and the other end connected to the fuel cell stack 10.

The high-pressure hydrogen tank 22 stores hydrogen to be supplied to the fuel cell stack 10 via the hydrogen supply pipe 21 and further to the anode electrode of each unit cell.

The hydrogen supply control unit 23 includes a main stop valve 231, a regulator 232, and an injector 233.

The main check valve 231 is an electromagnetic valve that is opened and closed by the electronic control unit 200, and is provided in the hydrogen supply pipe 21. When the main stop valve 231 is opened, hydrogen flows out from the high-pressure hydrogen tank 22 to the hydrogen supply pipe 21. When the main stop valve 231 is closed, the outflow of hydrogen from the high-pressure hydrogen tank 22 is stopped.

The regulator 232 is provided in the hydrogen supply pipe 21 downstream of the main stop valve 231. The regulator 232 is a pressure control valve capable of continuously or stepwise adjusting the opening degree, which is controlled by the electronic control unit 200. The pressure of hydrogen on the downstream side of the regulator 232, that is, the pressure of hydrogen injected from the injector 233 is controlled by controlling the opening degree of the regulator 232.

The injector 233 is provided in the hydrogen supply pipe 21 downstream of the regulator 232. The injector 233 is, for example, a needle valve, and is controlled to open and close by the electronic control unit 200. The flow rate of hydrogen injected from the injector 233 is controlled by controlling the valve opening time of the injector 233.

In this way, the hydrogen supply controller 23 controls the supply of hydrogen from the high-pressure hydrogen tank 22 to the fuel cell stack 10. That is, the hydrogen controlled to a desired pressure and flow rate by the hydrogen supply control unit 23 is supplied to the fuel cell stack 10.

The anode off-gas pipe 24 is a pipe through which the anode off-gas flowing out of the fuel cell stack 10 flows, and has one end connected to the fuel cell stack 10 and the other end connected to the gas inlet 25a of the gas-liquid separator 25. The anode off gas is a gas including excess hydrogen that is not used in the electrochemical reaction in each cell, an inert gas such as nitrogen that permeates from the cathode electrode side to the anode electrode side via the MEA1a, and moisture (liquid water, water vapor).

The gas-liquid separator 25 includes a gas inlet 25a, a gas outlet 25b, and a liquid water outlet 25 c. The gas-liquid separator 25 separates water in the anode off-gas flowing into the gas inlet 25 a. Then, the gas-liquid separator 25 discharges the separated water from the liquid water outlet 25c to the purge pipe 28, and discharges the anode off gas including hydrogen after separating the water from the gas outlet 25b to the hydrogen return pipe 26.

The hydrogen return pipe 26 is a pipe having one end connected to the gas outlet 25b of the gas-liquid separator 25 and the other end connected to the hydrogen supply pipe 21 downstream of the hydrogen supply control unit 23. The anode off-gas discharged from the gas outlet 25b of the gas-liquid separator 25 flows through the hydrogen return pipe 26.

The hydrogen circulation pump 27 is provided in the hydrogen return pipe 26. The hydrogen circulation pump 27 is a pump for returning and circulating hydrogen contained in the anode off gas, that is, excess hydrogen that is not used in the electrochemical reaction in each cell to the hydrogen supply pipe 21. The hydrogen circulation pump 27 pressurizes the anode off gas discharged from the gas outlet 25b of the gas-liquid separator 25 and pressure-feeds the anode off gas to the hydrogen supply pipe 21.

The purge pipe 28 is a pipe having one end connected to the liquid water outlet 25c of the gas-liquid separator 25 and the other end connected to a cathode off-gas pipe 38 described later.

The purge control valve 29 is an electromagnetic valve that is opened and closed by the electronic control unit 200, and is provided in the purge pipe 28. The purge control valve 29 is normally closed and periodically opened for a short time. When the purge control valve 29 is opened, the water separated in the gas-liquid separator 25 is discharged to the outside from the cathode off-gas pipe 38 through the purge pipe 28.

As described above, the fuel cell system 100 according to the present embodiment is a hydrogen circulation type fuel cell system that returns the anode off-gas flowing out from the hydrogen passage 2 to the hydrogen supply pipe 21 and circulates the anode off-gas, but may be a hydrogen non-circulation type fuel cell system that does not return the anode off-gas flowing out from the hydrogen passage 2 to the hydrogen supply pipe 21.

The air supply device 30 includes an air supply pipe 31, an air cleaner 32, a compressor 33, an intercooler 34, a cathode inlet valve 35, a bypass pipe 36, a flow divider valve 37, a cathode exhaust gas pipe 38, and a cathode pressure control valve 39.

The air supply pipe 31 is a pipe through which air supplied to the fuel cell stack 10 and further supplied to the cathode electrode of each unit cell flows, and has one end connected to the air cleaner 32 and the other end connected to the fuel cell stack 10.

The air cleaner 32 removes foreign substances from the air drawn into the air supply pipe 31. The air cleaner 32 is disposed in the atmosphere serving as the oxygen source 32 a. That is, the oxygen source 32a communicates with the air supply pipe 31 via the air cleaner 32.

The compressor 33 is, for example, a centrifugal or axial turbo compressor, and is provided in the air supply pipe 31. The compressor 33 compresses and discharges air drawn into the air supply pipe 31 via the air cleaner 32. Further, the air supply pipe 31 upstream of the compressor 33 is provided with a cathode flow rate sensor 211 for detecting a flow rate of air (hereinafter referred to as "total air supply rate") Qacp [ NL/min ] sucked into and discharged from the compressor 33.

The intercooler 34 is provided in the air supply pipe 31 downstream of the compressor 33, and cools the air discharged from the compressor 33 by, for example, running air, cooling water, or the like.

The cathode inlet valve 35 is an electromagnetic valve opened and closed by the electronic control unit 200, and is provided in the air supply pipe 31 downstream of the intercooler 34. The cathode inlet valve 35 is opened when air needs to be supplied to the fuel cell stack 10.

The bypass pipe 36 is a pipe for allowing a part or all of the air discharged from the compressor 33 to flow directly into a cathode off-gas pipe 38 described later, if necessary, without passing through the fuel cell stack 10. One end of the bypass pipe 36 is connected to the air supply pipe 31 between the intercooler 34 and the cathode inlet valve 35, and the other end is connected to a cathode exhaust gas pipe 38 downstream of a cathode pressure control valve 39, which will be described later.

The shunt valve 37 is provided to the bypass pipe 36. The flow dividing valve 37 is an electromagnetic valve capable of continuously or stepwise adjusting the opening degree, and the opening degree thereof is controlled by the electronic control unit 200.

The cathode off-gas pipe 38 is a pipe through which the cathode off-gas flowing out of the fuel cell stack 10 flows, and has one end connected to the fuel cell stack 10 and the other end opened to the atmosphere. The cathode off gas is a gas containing an excess of inert gas such as oxygen or nitrogen that is not used in the electrochemical reaction in each cell and moisture (liquid water or water vapor) generated by the electrochemical reaction.

A cathode pressure control valve 39 is provided to the cathode off-gas pipe 38. The cathode pressure control valve 39 is an electromagnetic valve capable of continuously or stepwise adjusting the opening degree thereof, and the opening degree thereof is controlled by the electronic control unit 200. The opening degree of the cathode pressure control valve 39 is controlled to control the pressure in the fuel cell stack 10, that is, the cathode pressure.

The flow rate of air supplied to the fuel cell stack 10 (hereinafter referred to as "FC air supply rate") Qfc [ NL/min ] of the air discharged from the compressor 33 is controlled by controlling the compressor 33 and, in turn, the respective opening degrees of the total air supply rate Qafc, the cathode inlet valve 35, the flow dividing valve 37, and the cathode pressure control valve 39.

The electrical load unit 50 includes a1 st converter 51, a breaker 52, a battery 53, a 2 nd converter 54, a motor generator 55, and an inverter 56.

A current sensor 212 for detecting a current Ifc [ a ] taken out of the fuel cell stack 10 (hereinafter referred to as "FC current") and a voltage sensor 213 for detecting an inter-terminal voltage of the output terminal of the fuel cell stack 10 (hereinafter referred to as "FC voltage") Vfc [ V ] are provided on a connection line 57 between the electrical load portion 50 and the output terminal of the fuel cell stack 10.

The 1 st converter 51 is a bidirectional DC/DC converter including a circuit capable of stepping up and down a voltage between terminals of a primary side terminal, the primary side terminal being connected to an output terminal of the fuel cell stack 10, and a secondary side terminal being connected to a DC side terminal of the inverter 56. The 1 st converter 51 steps up or down the FC output voltage Vfc, which is the voltage between the terminals on the primary side, based on a control signal from the electronic control unit 200, thereby controlling the FC current Ifc to the target FC current Itg set according to the operating state of the fuel cell system 100.

The circuit breaker 52 is opened and closed by the electronic control unit 200, and can electrically and physically connect and disconnect the fuel cell stack 10 and the electrical load unit 50.

The battery 53 is a chargeable and dischargeable secondary battery such as a nickel/cadmium battery, a nickel/hydrogen battery, or a lithium ion battery. The battery 53 is charged with surplus electric power of the fuel cell stack 10 and regenerative electric power of the motor generator 55. The electric power charged in the battery 53 is used to drive, as necessary, various control means provided in the fuel cell system 100 such as the motor generator 55 and the compressor 33.

The 2 nd converter 54 is, for example, a bidirectional DC/DC converter including a circuit capable of stepping up and down a voltage between terminals of a secondary side terminal, and the primary side terminal is connected to an output terminal of the battery 53 and the secondary side terminal is connected to a DC side terminal of the inverter 56. The 2 nd converter 54 steps up or down the input voltage of the inverter 56, which is the secondary side inter-terminal voltage, based on a control signal from the electronic control unit 200.

The motor generator 55 is, for example, a three-phase permanent magnet synchronous motor, and has a function as a motor for generating power of a vehicle on which the fuel cell system 100 is mounted and a function as a generator for generating power when the vehicle is decelerated. The motor generator 55 is connected to an ac-side terminal of the inverter 56, and is driven by the generated power of the fuel cell stack 10 and the power of the battery 53.

The inverter 56 includes a circuit capable of converting a direct current input from the direct current side terminal into an alternating current and outputting the alternating current from the alternating current side terminal based on a control signal from the electronic control unit 200, and conversely converting an alternating current input from the alternating current side terminal into a direct current and outputting the direct current from the direct current side terminal based on a control signal from the electronic control unit 200. The dc-side terminal of the inverter 56 is connected to the secondary-side terminals of the 1 st converter 51 and the 2 nd converter 54, and the ac-side terminal of the inverter 56 is connected to the input/output terminal of the motor generator 55. When the motor generator 55 is caused to function as a motor, the inverter 56 converts the direct current from the fuel cell stack 10 and the battery 53 into an alternating current (three-phase alternating current in the present embodiment) and supplies the alternating current to the motor generator 55. On the other hand, when the motor generator 55 is caused to function as a generator, the inverter 56 converts the ac current from the motor generator 55 into the dc current and supplies the dc current to the battery 53 and the like.

The electronic control unit 200 is constituted by a digital computer, and includes a ROM (read only memory) 202, a RAM (random access memory) 203, a CPU (microprocessor) 204, an input port 205, and an output port 206, which are connected to each other via a bidirectional bus 201.

In addition to the output signals of the cathode flow rate sensor 211, the current sensor 212, and the voltage sensor 213, output signals of an FC temperature sensor 214 for detecting the temperature of the fuel cell stack 10 (hereinafter referred to as "FC temperature") Tfc [ ° c ], a load sensor 215 for detecting the amount of depression of an accelerator pedal (hereinafter referred to as "accelerator depression amount"), a shift position detection sensor 216 for detecting a shift position (position of a shift lever) selected by the driver of the vehicle, a battery temperature sensor 217 for detecting the temperature of the battery 53 (hereinafter referred to as "battery temperature") Tvat, and the like are input to the input port 205 via the corresponding AD converters 207.

To the output port 206, control components such as the hydrogen supply control unit 23 (the main stop valve 231, the regulator 232, and the injector 233), the hydrogen circulation pump 27, the purge control valve 29, the compressor 33, the cathode inlet valve 35, the flow dividing valve 37, the cathode pressure control valve 39, the 1 st converter 51, the breaker 52, the 2 nd converter 54, and the inverter 56 are electrically connected via the corresponding drive circuit 208.

The electronic control unit 200 outputs control signals for controlling the respective control components from the output port 206 based on output signals of various sensors input to the input port 205 to control the fuel cell system 100. The control of the fuel cell system 100 by the electronic control unit 200, particularly the control of the FC air supply amount Qfc in the rapid warm-up operation at the time of the below-freezing start of the fuel cell system 100, will be described below.

Fig. 2 is a diagram showing a reference current-voltage characteristic (hereinafter referred to as "IV characteristic") of the fuel cell stack 10 when the stack temperature Tfc reaches a certain temperature. The reference IV characteristic is an IV characteristic when high-efficiency power generation (normal power generation) is performed in which various power generation losses generated during power generation are suppressed.

The electronic control unit 200 calculates a target generated power Ptg [ kW ] of the fuel cell stack 10 based on the operating state of the fuel cell system 100. In the present embodiment, the electronic control unit 200 calculates a total value of the requested power of the motor generator 55 and the requested power of various accessories such as the compressor 33 calculated based on the accelerator depression amount and the like as the target generated power Ptg.

As shown in fig. 2, during a normal operation in which high-efficiency power generation is performed after the warm-up of the fuel cell stack 10 is completed, the electronic control unit 200 controls the air stoichiometric ratio and further controls the FC air supply amount Qfc so that the operating point X defined by the FC current Ifc and the FC voltage Vfc becomes the normal operating point X1 at which the target generated power Ptg can be generated in the reference IV characteristic.

The air stoichiometric ratio is a ratio of the actual FC air supply amount Qfc to an FC air supply amount Qth that is minimally required to generate the target generated power Ptg (hereinafter referred to as "theoretical FC air supply amount"). Therefore, as the air stoichiometric ratio (═ Qfc/Qth) becomes greater than 1.0, the actual FC air supply amount Qfc becomes greater than the theoretical FC air supply amount Qth.

Fig. 3 is a diagram illustrating a relationship between the air stoichiometric ratio and an oxygen concentration overvoltage (power generation loss due to oxygen deficiency during power generation) which is a factor of the power generation loss.

As shown in fig. 3, the oxygen concentration overvoltage tends to become larger when the air stoichiometry is small than when the air stoichiometry is large. In other words, the power generation loss (voltage drop amount) due to the oxygen concentration overvoltage tends to be larger when the air stoichiometric ratio is small than when the air stoichiometric ratio is large.

Therefore, during the normal operation, in order to perform high-efficiency power generation with suppressed power generation loss, the electronic control unit 200 controls the FC air supply amount Qfc so that the air stoichiometric ratio becomes an air stoichiometric ratio in a normal region where the oxygen concentration overvoltage can be substantially ignored (in the example shown in fig. 3, the air stoichiometric ratio is near 1.5, for example).

On the other hand, when the fuel cell system 100 is started up and operated in an environment below freezing point, the electronic control unit 200 performs a rapid warm-up operation in order to suppress freezing of the produced water that is generated along with power generation and to recover the deteriorated IV characteristic as early as possible at a lower temperature. The rapid warm-up operation is an operation method in which the oxygen concentration overvoltage is increased more than in the normal operation by controlling the FC air supply amount Qfc to intentionally increase the power generation loss, thereby increasing the self-heating amount of the fuel cell stack 10 to promote the warm-up.

In the rapid warm-up operation, in order to generate the target generated power Ptg and perform low-efficiency power generation in which the power generation loss (self-heating value) is increased as compared with the normal operation, the electronic control unit 200 controls the FC air supply amount Qfc so that the air stoichiometric ratio becomes the air stoichiometric ratio in the rapid warm-up region (in the example shown in fig. 3, the air stoichiometric ratio in the vicinity of 1.0, for example) in which the oxygen concentration overvoltage cannot be ignored.

Thus, compared to the case where high-efficiency power generation (normal power generation) is performed at the normal operation point X1 on the reference IV characteristic in fig. 2, the FC voltage Vfc can be lowered by the oxygen concentration overvoltage amount corresponding to the air stoichiometric ratio. That is, by appropriately controlling the air stoichiometric ratio by controlling the FC current Ifc and further appropriately controlling the FC air supply amount Qfc, as shown in fig. 2, it is possible to generate power at a rapid warm-up operation point X2 that is located on the power line (see broken line) such as the normal operation point X1, has a power generation loss greater than the normal operation point X1, and can obtain a desired self-heating amount, and therefore, it is possible to promote warm-up of the fuel cell stack 10.

Here, as a result of intensive studies by the inventors: in the rapid warm-up operation, a difference tends to be generated between the target generated power Ptg and the actual generated power Pfc, and as a result, the battery charge/discharge power may increase and the battery may deteriorate. This problem will be described below with reference to fig. 4 in addition to fig. 3. Fig. 4 is a diagram showing changes in the FC voltage Vfc when the air stoichiometric ratio is changed while the FC current Ifc is kept constant (that is, when the FC air supply amount Qfc is changed).

As shown in fig. 3, when the change amount of the oxygen concentration overvoltage when the air stoichiometric ratio is changed by a predetermined amount is compared, the change amount tends to be larger when the air stoichiometric ratio is small than when the air stoichiometric ratio is large. In other words, when the air stoichiometric ratio is small, the voltage drop amount and hence the FC voltage Vfc tend to fluctuate more easily when the air stoichiometric ratio changes than when the air stoichiometric ratio is large.

Therefore, as shown in fig. 4, for example, in the normal operation in which the FC air supply amount Qfc is controlled so that the air stoichiometric ratio becomes a target air stoichiometric ratio SRtg1 within a normal region in which the above-described oxygen concentration overvoltage can be substantially ignored, even if the FC air supply amount Qfc fluctuates so that the air stoichiometric ratio deviates from the target air stoichiometric ratio SRtg1, the fluctuation amount of the FC voltage Vfc is small.

On the other hand, for example, in the rapid warm-up operation in which the FC air supply amount Qfc is controlled so that the air stoichiometric ratio becomes a certain target air stoichiometric ratio SRtg2 in the rapid warm-up region where the above-described oxygen concentration overvoltage cannot be ignored, if the FC air supply amount Qfc is varied and the air stoichiometric ratio is shifted from the target air stoichiometric ratio SRtg2, the FC voltage Vfc is greatly varied even if the shift width is the same as that in the normal operation.

In this way, in the rapid warm-up operation, when the air stoichiometric ratio deviates from the target air stoichiometric ratio, the variation amount of the FC voltage Vfc tends to be larger than that in the normal power generation.

Then, at the time of transition when the target generated power Ptg changes, the air stoichiometric ratio deviates from the target air stoichiometric ratio after the transition until the FC air supply amount Qfc is controlled to the target air supply amount Qtg after the transition. Therefore, during the rapid warm-up operation, particularly at the time of transition, the FC voltage Vfc tends to greatly deviate from the target FC voltage Vtg, and as a result, the actual generated power Pfc tends to greatly deviate from the target generated power Ptg.

When the actual generated power Pfc is greater than the target generated power Ptg, the battery 53 is charged with the excess power at this time. Therefore, when the excess power becomes large, the charging power of the battery 53 becomes equal to or more than the allowable charging power Win [ kW ] set according to the battery state in order to suppress deterioration of the battery 53, and there is a possibility that the battery 53 is deteriorated. In particular, when a lithium ion battery is used as the battery 53, if the surplus power becomes large, so-called lithium deposition in which lithium is deposited on the surface of the negative electrode of the battery 53 may occur.

When the actual generated power Pfc is smaller than the target generated power Ptg, the battery 53 outputs the insufficient power at that time. Therefore, when the insufficient electric power becomes large, the discharge electric power of the battery 53 becomes equal to or more than the allowable discharge electric power Wout [ kW ] set according to the battery state in order to suppress deterioration of the battery 53, similarly to the allowable charge electric power Win, and there is a possibility that the battery 53 is deteriorated.

In the present embodiment, the charging power of the battery 53 is a positive value whose value increases as the charging power of the battery 53 increases. Similarly, the discharge power of the battery 53 is a positive value whose value increases as the discharge power from the battery 53 increases.

The allowable charge power Win and the allowable discharge power Wout change depending on the state of the battery 53, and tend to be smaller when the temperature of the battery 53 is low than when the temperature of the battery 53 is high, for example. Therefore, during the rapid warm-up operation performed in an environment substantially below freezing point, the temperature of battery 53 is also low, and therefore allowable charge power Win and allowable discharge power Wout tend to be smaller than during the normal operation. Therefore, if the actual generated power Pfc and the target generated power Ptg deviate from each other during the rapid warm-up operation, the battery 53 is likely to be in an overcharged state or an overdischarged state, and the battery 53 is likely to deteriorate.

In view of this, in the present embodiment, the target heat generation amount PLtg [ W ] in the rapid warm-up operation is changed based on the state of the vehicle on which the fuel cell system 100 is mounted and the state of the battery.

Specifically, when the vehicle state is the 1 st state (1 st mode) in which the parking range (hereinafter referred to as "P range") is selected as the shift range, the target heat generation amount PLtg in the rapid warm-up operation is set to the predetermined 1 st heat generation amount PL1 having the largest heat generation amount.

When the vehicle state is the 2 nd state (the 2 nd mode) in which the forward gear (hereinafter referred to as "D gear") or the reverse gear (hereinafter referred to as "R gear") is selected as the shift gear, the target heat generation amount PLtg in the rapid warm-up operation is set to the predetermined 2 nd heat generation amount PL2 having a heat generation amount smaller than the 1 st heat generation amount PL 1.

This is because of the following reason. That is, the larger the target heat generation amount PLtg during the rapid warm-up operation is, the smaller the air stoichiometric ratio is required to increase the oxygen concentration overvoltage and increase the power generation loss. Therefore, the larger the value of the target heat generation amount PLtg during the rapid warm-up operation, the more likely the deviation between the actual generated power Pfc and the target generated power Ptg occurs particularly at the time of transition.

Further, when the vehicle is in the parking state with the P range selected as the shift range, since the accelerator pedal is not depressed basically, the target generated power Ptg is changed to the transient state less frequently, and the change amount is small if the change occurs. On the other hand, when the D range or the R range is selected as the shift range, since the accelerator pedal is basically depressed, the target generated power Ptg changes to a transient state more frequently, and the amount of change increases.

In view of this, in the present embodiment, when the P range is selected as the shift range, the target heat generation amount PLtg is set to the 1 st heat generation amount PL1 having the largest heat generation amount, and when the D range or the R range is selected as the shift range, the target heat generation amount PLtg is set to the 2 nd heat generation amount PL2 having a heat generation amount smaller than the 1 st heat generation amount PL 1.

This increases the amount of heat generated when the shift speed is the P speed, and the warm-up of the fuel cell stack 10 can be quickly achieved. When the shift range is switched to the D range or the R range, the amount of heat generation is suppressed to some extent, so that the fuel cell stack 10 can be warmed up, and the battery 53 can be prevented from being overcharged or overdischarged by suppressing the deviation between the actual generated power Pfc and the target generated power Ptg.

When the D range or the R range is selected as the shift range, if the allowable charge power Win and the allowable discharge power Wout of the battery 53 determined according to the battery state are respectively reduced, the battery 53 is likely to be in an overcharged state or an overdischarged state if the actual generated power Pfc and the target generated power Ptg deviate from each other. Therefore, in the present embodiment, when the D range or the R range is selected as the shift range, when the allowable charge power Win and the allowable discharge power Wout of the battery 53 are smaller than the charge-side threshold value and the discharge-side threshold value, respectively, the target heat generation amount PLtg in the rapid warm-up operation is set to the predetermined 3 rd heat generation amount PL3 whose heat generation amount is further smaller than the 2 nd heat generation amount PL 2.

Thus, when battery 53 is likely to be in an overcharged state or an overdischarged state, the amount of heat generation can be further suppressed, and the occurrence of a deviation between actual generated power Pfc and target generated power Ptg can be further suppressed.

Therefore, in the present embodiment, in order to increase the oxygen concentration overvoltage and increase the power generation loss to promote warm-up, the 1 st heat generation amount PL1 is set to a heat generation amount (for example, 50 to 60 kW) such that the air stoichiometric ratio becomes a value in the vicinity of 1.0.

In order to suppress the fluctuation of the FC voltage Vfc when the air stoichiometric ratio deviates from the target air stoichiometric ratio and thereby suppress the battery 53 from being in an overcharged state or an overdischarged state, the 3 rd heat generation amount PL3 is set to a heat generation amount (for example, 5 to 10 kW) such that the air stoichiometric ratio becomes an air stoichiometric ratio (for example, around 1.5) close to the air stoichiometric ratio in the normal operation.

In addition, in consideration of the balance between the warm-up acceleration and the suppression of deterioration due to overcharge or overdischarge of the battery 53, the 2 nd heat generation amount PL2 is set to a heat generation amount (for example, 20 to 30 kW) substantially midway between the 1 st heat generation amount PL1 and the 3 rd heat generation amount PL 3.

Hereinafter, the control of the FC air supply amount Qfc in the rapid warm-up operation according to the present embodiment including the process of setting the target heat generation amount PLtg in the rapid warm-up operation will be described with reference to fig. 5.

Fig. 5 is a flowchart illustrating control of the FC air supply amount Qfc in the rapid warm-up operation according to the present embodiment. The electronic control unit 200 repeatedly executes the present routine at a predetermined calculation cycle (for example, 10 ms).

In step S1, the electronic control unit 200 determines whether the quick warm-up flag F is set to 0. The rapid warm-up flag F is a flag whose initial value is set to 0, which is set to 1 at the start of the rapid warm-up operation, and which returns to 0 at the end of the rapid warm-up operation. If the quick warm-up flag F is 0, the electronic control unit 200 proceeds to the process of step S2. On the other hand, if the quick warm-up flag F is 1, the electronic control unit 200 proceeds to the process of step S4.

In step S2, the electronic control unit 200 determines whether or not there is a request for implementation of the rapid warm-up. In the present embodiment, the ecu 200 determines that there is a request for execution of the rapid warm-up operation if the FC temperature is equal to or lower than a predetermined rapid warm-up request temperature (e.g., 0[ ° c ]) at the time of start-up of the fuel cell system 100. When it is determined that there is a request for implementation of the rapid warm-up operation, the electronic control unit 200 proceeds to the process of step S3. On the other hand, when it is determined that there is no request for execution of the rapid warm-up operation, the electronic control unit 200 ends the current process.

In step S3, the electronic control unit 200 sets the rapid warmup flag F to 1.

In step S4, the electronic control unit 200 calculates a target generated power Ptg of the fuel cell stack 10 based on the operating state of the fuel cell system 100. In the present embodiment, as described above, the electronic control unit 200 calculates the total value of the requested power of the motor generator 55 and the requested power of various accessories such as the compressor 33 as the target generated power Ptg.

In step S5, the electronic control unit 200 performs a setting process of the target heat generation amount PLtg. In order to facilitate understanding of the invention, before the description of step S6 and the subsequent steps, the process of setting the target heat generation amount PLtg will be described first with reference to fig. 6.

Fig. 6 is a flowchart for explaining the setting process of the target heat generation amount PLtg in detail.

In step S51, electronic control unit 200 determines whether or not the shift speed of the vehicle is P speed. If the shift speed of the vehicle is the P speed, the electronic control unit 200 proceeds to the process of step S52. On the other hand, if the shift speed of the vehicle is a speed other than the P speed (for example, the D speed or the R speed), the electronic control unit 200 proceeds to the process of step S53.

In step S52, the electronic control unit 200 sets the target heat generation amount PLtg to the 1 st heat generation amount PL 1.

In step S53, electronic control unit 200 calculates allowable charge electric power Win and allowable discharge electric power Wout based on the state of battery 53. In the present embodiment, electronic control unit 200 calculates allowable charge power Win and allowable discharge power Wout based on battery temperature Tvat. As described above, allowable charge power Win and allowable discharge power Wout are in a tendency to become smaller when battery temperature Tvat is low than when battery temperature Tvat is high, respectively. In addition, in the calculation of allowable charge power Win and allowable discharge power Wout, in addition to battery temperature Tvat, for example, a battery charging rate or the like may be considered.

In step S54, the electronic control unit 200 sets the tentative target heat generation amount PLtg'. The provisional target heat generation amount PLtg' is basically set to the last value of the target heat generation amount PLtg, but is set to the 3 rd heat generation amount PL3 in the present embodiment when the last value of the target heat generation amount PLtg is the 1 st heat generation amount PL 1.

In step S55, the electronic control unit 200 determines whether or not the permitted charging power Win is equal to or greater than a prescribed 1 st charging-side threshold Win 1. If the allowable charging power Win is equal to or greater than the 1 st charging-side threshold Win1, the electronic control unit 200 proceeds to the process of step S56. On the other hand, if the permissible charging power Win is smaller than the 1 st charging-side threshold Win1, the electronic control unit 200 proceeds to the process of step S58.

In step S56, electronic control unit 200 determines whether or not permissible discharge power Wout is equal to or greater than a predetermined 1 st discharge-side threshold value Wout 1. When allowable charging power Wout is equal to or greater than 1 st discharge-side threshold value Wout1, electronic control unit 200 proceeds to the process of step S57. On the other hand, if allowable charging power Wout is smaller than 1 st discharge-side threshold value Wout1, electronic control unit 200 proceeds to the process of step S58.

In step S57, the electronic control unit 200 sets the target heat generation amount PLtg to the 2 nd heat generation amount PL 2.

In step S58, the electronic control unit 200 determines whether the allowable charging power Win is smaller than a prescribed 2 nd charging-side threshold Win2 that is smaller than a1 st charging-side threshold Win 1. If the allowable charging power Win is smaller than the 2 nd charging-side threshold Win2, the electronic control unit 200 proceeds to the process of step S59. On the other hand, if the permissible charging power Win is equal to or greater than the 2 nd charging-side threshold Win2, the electronic control unit 200 proceeds to the process of step S60.

In step S59, the electronic control unit 200 sets the target heat generation amount PLtg to the 3 rd heat generation amount PL 3.

In step S60, electronic control unit 200 determines whether or not permissible discharge power Wout is smaller than a prescribed 2 nd discharge-side threshold value Wout2 that is smaller than 1 st discharge-side threshold value Wout 1. If allowable charging power Wout is smaller than 2 nd discharge-side threshold value Wout2, electronic control unit 200 proceeds to the process of step S59. On the other hand, when allowable charging power Wout is equal to or greater than 2 nd discharge-side threshold value Wout2, electronic control unit 200 proceeds to the process of step S61.

In step S61, the electronic control unit 200 sets the target heat-generation amount PLtg to the provisional target heat-generation amount PLtg'.

In this way, in the present embodiment, when the shift speed of the vehicle is a speed other than the P speed (for example, the D speed or the R speed), the target heat generation amount PLtg is set to the 2 nd heat generation amount PL2 when the allowable charge electric power Win is equal to or greater than the 1 st charge-side threshold Win1 and the allowable discharge electric power Wout is equal to or greater than the 1 st discharge-side threshold Wout 1. Then, if the allowable charging electric power Win is smaller than the 2 nd charging-side threshold value Win2 or the allowable discharging electric power Wout is smaller than the 2 nd discharging-side threshold value Wout2, the target heat generation amount PLtg is set to the 3 rd heat generation amount PL 3.

Returning to fig. 5, in step S6, the electronic control unit 200 refers to the IV characteristic map shown in fig. 7, in which the equivalent power line (thin solid line) and the equivalent heat generation amount line (thick solid line) are plotted, and calculates the rapid warming operation point X2, that is, the target FC current Itg [ a ] and the target FC voltage Vtg [ V ], based on the target generated power Ptg and the target heat generation amount PLtg.

Specifically, the electronic control unit 200 selects an iso-electric power line from among the iso-electric power lines that can generate the target generated power Ptg as shown in fig. 8, and calculates a point at which the selected iso-electric power line intersects an iso-heat generation amount line that can generate the heat amount at the target heat generation amount PLtg on the IV characteristic map as the rapid warming operation point X2.

In fig. 7 and 8, the equal heat generation amount line L1 is an equal heat generation amount line that can generate the 1 st heat generation amount PL1, the equal heat generation amount line L2 is an equal heat generation amount line that can generate the 2 nd heat generation amount PL2, and the equal heat generation amount line L3 is an equal heat generation amount line that can generate the 3 rd heat generation amount PL 3.

In step S7, the electronic control unit 200 calculates an FC voltage (hereinafter referred to as "reference FC voltage") Vstd at the time of controlling the FC current Ifc to the target FC current Itg on the reference IV characteristic with reference to the reference IV characteristic map shown in fig. 9. In other words, the reference FC voltage Vstd is an FC voltage at which the FC current Ifc is controlled to the target FC current Itg by performing high-efficiency power generation (normal power generation).

Here, since the reference IV characteristic changes depending on the FC temperature Tfc, a plurality of reference IV characteristic maps are prepared for each FC temperature. Therefore, the electronic control unit 200 calculates the reference FC voltage Vstd with reference to the best reference IV characteristic map corresponding to the current FC temperature Tfc from among the plurality of reference IV characteristic maps.

In step S8, the electronic control unit 200 refers to the map showing the relationship between the air stoichiometric ratio and the oxygen concentration overvoltage shown in fig. 10, which is the same as fig. 3, and calculates the reference air stoichiometric ratio SRstd based on Δ V1 (Vstd-Vtg) which is the difference between the reference FC voltage Vstd and the target FC voltage Vtg (i.e., the oxygen concentration overvoltage that needs to be generated to lower the reference FC voltage Vstd to the target FC voltage Vtg).

In step S9, the electronic control unit 200 calculates a feedback correction value for the reference air stoichiometric ratio SRstd based on the deviation (hereinafter referred to as "FC voltage deviation") Δ V2 (Vtg-Vfc) of the target FC voltage Vtg from the FC voltage Vfc, and adds the feedback correction value to the reference air stoichiometric ratio SRstd, thereby calculating the target air stoichiometric ratio SRtg.

In step S10, the electronic control unit 200 calculates the target FC air supply amount Qtg by multiplying the target air stoichiometric ratio SRtg by the theoretical FC air supply amount Qth required to generate the target generated power Ptg.

In step S11, the electronic control unit 200 controls the 1 st converter 51 to control the FC current Ifc to the target FC current Itg, and controls the FC air supply amount Qfc to the target air supply amount Qtg. In the present embodiment, the electronic control unit 200 controls the compressor so that the total air supply amount Qafc is constant, and controls the opening degrees of the flow dividing valve 37 and the cathode pressure control valve to control the FC air supply amount Qfc to the target air supply amount Qtg.

In this way, by controlling the FC current Ifc to the target FC current Itg and controlling the FC air supply amount Qfc to the target air supply amount Qtg, the FC voltage Vfc is controlled to the target FC voltage Vtg, and the operation point X is controlled to the rapid warming operation point X2.

In step S12, the electronic control unit 200 determines whether or not the warm-up of the fuel cell stack is completed. In the present embodiment, the electronic control unit 200 determines whether or not the FC temperature Tfc becomes a predetermined rapid warm-up completion temperature (e.g., 70[ ° c ]) or more. If the FC temperature Tfc is equal to or higher than the quick warm-up completion temperature, the electronic control unit 200 proceeds to the process of step S13. On the other hand, if the FC temperature Tfc is less than the rapid warm-up completion temperature, the electronic control unit 200 ends the process this time.

In step S13, the electronic control unit 200 ends the rapid warm-up operation, and returns the rapid warm-up flag F to 0.

The fuel cell system 100 according to the present embodiment described above includes: a fuel cell stack 10 (fuel cell) that generates electric power by an electrochemical reaction of hydrogen as a fuel gas and air as an oxidant gas; a battery 53 (secondary battery) that is charged with surplus electric power at the time of power generation by the fuel cell stack 10 and discharges insufficient electric power; and an electronic control unit 200 (control means). The electronic control unit 200 includes: a supply flow rate control unit configured to control a supply flow rate of air (FC air supply amount Qfc) supplied to the fuel cell stack 10; and a power generation implementation unit configured to implement low-efficiency power generation with a power generation loss larger than that of normal power generation.

In the low-efficiency power generation, when the vehicle (vehicle) on which the fuel cell system 100 is mounted is in the 1 st mode in which the P range is selected as the shift range, the supply flow rate control unit controls the FC air supply amount Qfc so that the heat generation amount of the fuel cell stack 10 due to the power generation loss becomes the 1 st heat generation amount PL1, and when the vehicle is in the 2 nd mode in which the D range or the R range is selected as the shift range in which the power generation amount of the fuel cell stack 10 is likely to fluctuate compared to the 1 st mode, the supply flow rate control unit controls the FC air supply amount Qfc so that the heat generation amount becomes the 2 nd heat generation amount PL2 smaller than the 1 st heat generation amount PL 1.

Thus, when the shift speed is the P speed, the amount of heat generated by the fuel cell stack 10 is increased, and the warm-up of the fuel cell stack 10 can be promptly achieved. When the shift range is switched to the D range or the R range, the amount of heat generation is suppressed to some extent, so that the fuel cell stack 10 is warmed up, and the deviation between the actual generated power Pfc and the target generated power Ptg is suppressed, thereby suppressing the battery from being in the overcharged state or the overdischarged state.

The supply flow rate control unit according to the present embodiment controls the FC air supply amount Qfc so that the heat generation amount in the 2 nd mode becomes the 3 rd heat generation amount PL3 smaller than the 2 nd heat generation amount PL2, based on at least one of the allowable charge power Win or the allowable discharge power Wout of the battery 53 determined in accordance with the battery state.

Specifically, when the vehicle state is the 2 nd mode, if allowable charge power Win is smaller than a predetermined 2 nd charge-side threshold value Win2 smaller than a predetermined 1 st charge-side threshold value Win1 or if allowable discharge power Wout is smaller than a predetermined 2 nd discharge-side threshold value Wout2 smaller than a predetermined 1 st discharge-side threshold value Wout1, the supply flow rate control unit controls FC air supply amount Qfc so that the generated heat amount becomes the 3 rd generated heat amount PL3, and if allowable charge power Win is equal to or greater than the 1 st charge-side threshold value Win1 and allowable discharge power Wout is equal to or greater than the 1 st discharge-side threshold value Wou1, the supply flow rate control unit controls FC air supply amount Qfc so that the generated heat amount becomes the 2 nd PL 2.

When the actual generated power Pfc and the target generated power Ptg deviate from each other as allowable charge power Win or allowable discharge power Wout of the battery is smaller, the battery is more likely to be in an overcharged state or an overdischarged state. In contrast, in the present embodiment, when the allowable charge power Win or the allowable discharge power Wout of the battery is small, the heat generation amount can be suppressed to the 3 rd heat generation amount PL3 that is lower than the 2 nd heat generation amount PL2, and therefore, the occurrence of a deviation between the actual generated power Pfc and the target generated power Ptg can be further suppressed. Therefore, the battery can be prevented from being overcharged or overdischarged.

While the embodiments of the present invention have been described above, the above embodiments are merely some of application examples of the present invention, and the technical scope of the present invention is not limited to the specific configurations of the above embodiments.

For example, in the above-described embodiment, the case where the fuel cell system 100 is mounted on a vehicle is described as an example, but the present invention is not limited to the vehicle, and may be mounted on various mobile bodies or may be mounted on a stationary power generation facility. Therefore, the 1 st mode is not limited to the case where the P range is selected as the shift range, and the 2 nd mode is also not limited to the case where the D range or the R range is selected as the shift range.

In the above-described embodiment, in order to prevent occurrence of hunting that occurs repeatedly when the target heat generation amount PLtg is switched in the target heat generation amount setting process, the 2 nd charging-side threshold value Win2 when the target heat generation amount PLtg is switched from the 2 nd heat generation amount PL2 to the 3 rd heat generation amount PL3 and the 1 st charging-side threshold value Win1 when the target heat generation amount PLtg is switched from the 3 rd heat generation amount PL3 to the 2 nd heat generation amount PL2 are made different values, respectively. Similarly, the 2 nd discharge-side threshold value Wout2 when the target heat generation amount PLtg is switched from the 2 nd heat generation amount PL2 to the 3 rd heat generation amount PL3 and the 1 st charge-side threshold value Wout1 when the target heat generation amount PLtg is switched from the 3 rd heat generation amount PL3 to the 2 nd heat generation amount PL2 are different values, respectively. However, as shown in the flowchart of fig. 11, the charge-side threshold value may be fixed to either Win1 or Win2, and similarly, the discharge-side threshold value may be fixed to either Wout1 or Wout 2. That is, the supply flow rate control unit may be configured to control the supply flow rate of the oxidizing gas so that the heat generation amount in the 2 nd mode becomes the 3 rd heat generation amount PL3 when the allowable charging electric power Win is smaller than the predetermined charging-side threshold value, or may be configured to control the supply flow rate of the oxidizing gas so that the heat generation amount in the 2 nd mode becomes the 3 rd heat generation amount PL3 when the allowable discharging electric power Wout is smaller than the predetermined discharging-side threshold value.