JP6790510B2 - Fuel cell system and control method of fuel cell system - Google Patents

Description

The present invention relates to a fuel cell system and a method for controlling a fuel cell system.

Patent Document 1 describes a combined power generation system of a fuel cell and a gas turbine, which includes a turbine, a compressor driven by the turbine, an electric motor (electric motor) for driving the compressor, a fuel cell, and a compressor. A fuel cell system including a first gas supply flow path for supplying compressed compressed gas to a fuel cell and a first exhaust gas flow path for supplying exhaust gas discharged from the fuel cell to a turbine is disclosed. In the system of Patent Document 1, it is described that when the required generated power (system required output) is large, the combustor is operated to supply combustion gas to the turbine to drive the turbine.

Japanese Unexamined Patent Publication No. 2005-135835

However, the fuel cell system of Patent Document 1 merely performs general power source switching control in which the electric motor is stopped and the compressor is driven by the turbine recovery power when the load is high. Therefore, since the power to satisfy the required generated power is basically secured by the electric motor, it is necessary to have a margin in the power that can be output by the electric motor, and the electric motor becomes large, and eventually the entire system. There is a problem that it leads to an increase in size.

According to an aspect of the present invention, a fuel supply device that supplies fuel to the anode electrode of a fuel cell, an oxidant supply device that supplies an oxidant to the cathode electrode of the fuel cell, and an operation for detecting an operating state of the fuel cell. A fuel cell system including a state detection unit and an operation control device that controls a fuel supply device and an oxidant supply device by a signal from an operation state detection unit. The oxidant supply device includes a compressor and the compressor. The operation control device includes an electric motor to be driven, and the operation control device includes a steady state determination unit for determining whether or not the system is in a steady operation state, and an output upper limit of the electric motor based on a determination result by the steady state determination unit. A motor output upper limit value setting unit that sets a value, a system request output calculation unit that calculates a system request output corresponding to the running power of the vehicle based on the accelerator pedal operation amount of the vehicle on which the fuel cell system is mounted, and a system request output calculation unit. It has a target power generation current setting unit that sets the target power generation current of the fuel cell based on the calculated system required output, and the motor output upper limit value setting unit moves from the fuel cell to the electric motor based on the target power generation current. The maximum generated power required motor power corresponding to the power to be supplied is calculated, and the maximum generated power required motor power is a high load region where the target generated current is equal to or more than the predetermined value than the low / medium load region where the target generated current is less than the predetermined value. Provided is a fuel cell system that calculates to a low value in.

According to an aspect of the present invention, the output of the electric motor can be limited, and the electric motor can be made compact. As a result, the miniaturization of the system is realized.

FIG. 1 is a schematic configuration diagram of a fuel cell system according to the present embodiment. FIG. 2 is a flowchart illustrating an operating state of the fuel cell system. FIG. 3 is a flowchart showing the flow of the target stack current calculation. FIG. 4 is a flowchart showing the flow of the cooling system operation amount calculation. FIG. 5 is a flowchart showing the flow of air system operation amount calculation. FIG. 6 is a flowchart showing the flow of fuel system operation amount calculation. FIG. 7 is a flowchart illustrating control of the air system in more detail. FIG. 8 is a flowchart illustrating the details of calculation of the steady-state operation motor power upper limit value. FIG. 9 is a block diagram illustrating control of the air system. FIG. 10 is a block diagram illustrating a more detailed function of the air system control unit. FIG. 11 is a block diagram showing a function of calculating the turbine inlet air pressure. FIG. 12 is a block diagram showing a turbine efficiency calculation function. FIG. 13 is a diagram showing an outline of a power generation power requirement maximum motor power map. FIG. 14 is a block diagram showing a function of calculating the stack output limit value. FIG. 15 is a chart illustrating an operating state of the fuel cell system of the present embodiment. FIG. 16 is a time chart showing an example of the flow over time in the control of the fuel cell system of the present embodiment.

Hereinafter, embodiments of the present invention will be described with reference to the drawings and the like.

(First Embodiment)
FIG. 1 is a schematic configuration diagram of a fuel cell system according to the first embodiment of the present invention.

As shown in the figure, the fuel cell system 100 according to the first embodiment of the present invention is a turbo supercharger 16 having a fuel cell stack 10, a cathode supply / discharge mechanism 12, an anode supply mechanism 14, a compressor 64, and a turbine 62. It has a heating / cooling mechanism 17, an HFR measuring device 18, a load device 19, and a controller 20.

The fuel cell stack 10 is a laminated battery in which a plurality of fuel cells are laminated. The fuel cell stack 10 receives the supply of anode gas (hydrogen) as fuel from the anode supply mechanism 14 and the cathode gas (air) as an oxidant from the cathode supply / discharge mechanism 12, and is required for traveling of the vehicle. Power is generated. This generated power is used in various auxiliary machines such as the compressor 64 and a traveling motor for driving wheels (not shown). Further, the HFR measuring device 18 and the load device 19 are connected to the positive electrode terminal and the negative electrode terminal of the fuel cell stack 10.

The cathode supply / discharge mechanism 12 includes a cathode gas supply passage 22 and a cathode gas discharge passage 24.

The cathode gas supply passage 22 is a passage through which the air supplied to the fuel cell stack 10 flows. One end of the cathode gas supply passage 22 is connected to the intake inlet of the compressor 64, and the other end is connected to the fuel cell stack 10.

The cathode gas discharge passage 24 is a passage through which the cathode exhaust gas discharged from the fuel cell stack 10 flows. One end of the cathode gas discharge passage 24 is connected to the fuel cell stack 10, and the other end is connected to the turbine 62.

An air flow meter 26 and an air pressure sensor 28 are provided in the cathode gas supply passage 22 in this order from the upstream. Further, the cathode gas discharge passage 24 is provided with a stack outlet temperature sensor 30, a combustor 32, and a nozzle vane 34 in this order from the upstream.

The air flow meter 26 is provided at the intake inlet of the compressor 64 of the turbocharger 16 in the cathode gas supply passage 22. The air flow meter 26 detects the flow rate of air sucked into the compressor 64 (hereinafter, also referred to as “air flow rate”). The signal of the air flow rate detection value detected by the air flow meter 26 is input to the controller 20.

The air pressure sensor 28 detects the pressure of the cathode gas supply passage 22 discharged from the compressor 64 (hereinafter, also referred to as “air pressure”). The signal of the air pressure detection value detected by the air pressure sensor 28 is input to the controller 20.

Further, in the cathode gas supply passage 22, a bypass passage 36 connected between the stack outlet temperature sensor 30 of the cathode gas discharge passage 24 and the combustor 32 is connected between the compressor 64 and the air pressure sensor 28. ..

The bypass passage 36 bypasses the fuel cell stack 10 and supplies a part of the air sucked into the cathode gas supply passage 22 by the compressor 64 to the cathode gas discharge passage 24. A bypass valve 38 is provided in the bypass passage 36. The bypass valve 38 regulates the flow rate of air flowing through the bypass passage 36.

The bypass valve 38 is controlled to open and close by the controller 20. For example, when the flow rate of air sucked into the cathode gas supply passage 22 by the compressor 64 exceeds the flow rate of air required for power generation by the fuel cell stack 10, the controller 20 increases the opening degree of the bypass valve 38. .. As a result, the bypass flow rate is increased, and overdrying of the electrolyte membrane in the fuel cell stack 10 is prevented.

The stack outlet temperature sensor 30 detects the temperature of the cathode exhaust gas discharged from the fuel cell stack 10 (hereinafter, also referred to as the stack outlet temperature). The signal of the stack outlet temperature detection value detected by the stack outlet temperature sensor 30 is input to the controller 20.

The combustor 32 catalytically burns a mixed gas obtained by mixing hydrogen and cathode exhaust gas with a mixer (not shown) by catalytic action of platinum or the like, and discharges the gas (combustion gas) remaining after combustion. Hydrogen is supplied to the combustor 32 from the high-pressure tank 40 of the anode supply mechanism 14, while the cathode exhaust gas obtained by mixing the cathode exhaust gas from the fuel cell stack 10 and the air from the bypass passage 36 is supplied. ..

In this embodiment, since the catalytic combustion type combustor is used as the combustor 32, the nitrogen compound (Nox) is compared with the case where the diffusion combustion type combustor or the dilute premixed combustion type combustor is used. ) Is suppressed. However, a combustor other than the catalytic combustor, such as a diffusion combustion type combustor or a dilute premixed combustion type combustor, may be used.

Further, a turbine bypass passage 39 is connected between the combustor 32 and the nozzle vane 34 in the cathode gas discharge passage 24. The turbine bypass passage 39 supplies a part of the combustion gas from the combustor 32 to the heating / cooling mechanism 17.

That is, when the fuel cell stack 10 is warmed up, a part of the combustion gas is supplied to the heating / cooling mechanism 17, and the fuel cell stack 10 is warmed up by the heat of the combustion gas, so that the warming up can be promoted. Further, the combustion gas supplied from the turbine bypass passage 39 to the heating / cooling mechanism 17 and after the heat is recovered by the heating / cooling mechanism 17 joins the turbine exhaust passage 68, which will be described later, to the outside of the fuel cell system 100. It is discharged.

The nozzle vane 34 adjusts the pressure of the combustion gas supplied to the turbine 62. The opening degree (nozzle lift amount) of the nozzle vane 34 is controlled by the controller 20. In the open state of the nozzle vane 34, the cross-sectional area of the inlet flow path to the turbine 62 increases, and the pressure loss of the combustion gas flowing into the turbine 62 from the cathode gas discharge passage 24 becomes relatively small. On the other hand, in the closed state of the nozzle vane 34, the cross-sectional area of the inlet flow path to the turbine 62 is relatively reduced, and the pressure loss is increased. That is, the air pressure can be reduced as the nozzle vane opening degree increases.

Next, the anode supply mechanism 14 will be described. The anode supply mechanism 14 in the present embodiment includes a high-pressure tank 40, a hydrogen heater 42, a hydrogen supply passage 44 for a stack, and a hydrogen supply passage 46 for a combustor.

The high-pressure tank 40 is a gas storage container that stores hydrogen supplied to the fuel cell stack 10 and the combustor 32 in a high-pressure state.

The hydrogen heater 42 is a heat exchanger that heats hydrogen from the high pressure tank 40 by the heat supplied from the heating / cooling mechanism 17. Specifically, the hydrogen from the high-pressure tank 40 is heated by exchanging heat with the cooling water of the fuel cell stack 10 in the heating / cooling mechanism 17.

The stack hydrogen supply passage 44 is a passage for supplying hydrogen discharged from the high-pressure tank 40 to the anode pole of the fuel cell stack 10. One end of the stack hydrogen supply passage 44 is connected to the hydrogen heater 42, and the other end is connected to the fuel cell stack 10.

Further, a stack supply hydrogen pressure regulating valve 48 is provided in the stack hydrogen supply passage 44. The stack supply hydrogen pressure regulating valve 48 is opened and closed controlled by the controller 20, and the pressure of hydrogen supplied to the fuel cell stack 10 is adjusted.

On the other hand, the hydrogen supply passage 46 for the combustor is a passage for supplying a part of the hydrogen discharged from the high pressure tank 40 to the combustor 32. One end of the combustor hydrogen supply passage 46 communicates with the stack hydrogen supply passage 44 and branches, and the other end is connected to the combustor 32.

Further, the hydrogen supply passage 46 for the combustor is provided with a hydrogen pressure detection sensor 47 for detecting the pressure of hydrogen upstream of the hydrogen supply passage 46 for the combustor (hereinafter, also referred to as “hydrogen supply pressure”). The signal of the hydrogen pressure detection value supplied by the hydrogen pressure detection sensor 47 is input to the controller 20.

Further, the combustor hydrogen supply passage 46 is provided with a combustor hydrogen amount adjusting valve 49 for arbitrarily adjusting the amount of hydrogen supplied (fuel supply amount) to the combustor 32. The combustor hydrogen amount adjusting valve 49 is a valve that appropriately adjusts the amount of hydrogen supplied to the combustor 32. The opening degree of the combustor hydrogen amount control valve 49 is adjusted by the controller 20. The combustor hydrogen amount control valve 49 can be composed of, for example, a proportional solenoid or the like.

In the fuel cell system 100 according to the present embodiment, the anode exhaust gas from the fuel cell stack 10 can be treated by an anode discharge system (not shown) such as a circulating type or a non-circulating type.

Next, the turbocharger 16 will be described. The turbocharger 16 includes a turbine 62 and a compressor 64. Further, the turbocharger 16 of the present embodiment is provided with an electric motor 60.

The electric motor 60 is connected to the compressor 64 on one side of the rotary drive shaft 66 and is connected to the turbine 62 on the other side of the rotary drive shaft 66. The electric motor 60 has a function as an electric motor (power running mode) for rotationally driving the compressor 64 by receiving electric power from a battery (not shown) and a fuel cell stack 10, and generates electric power by being rotationally driven by an external force, such as a battery. It has a function (regeneration mode) as a generator that supplies electric power to the battery. The electric motor 60 includes a motor case (not shown), a stator fixed to the inner peripheral surface of the motor case, and a rotor rotatably arranged inside the stator, and the rotor is integrated with the rotary drive shaft 66. Attached to.

Further, the electric motor 60 is provided with a rotation speed sensor 72. The rotation speed sensor 72 detects the rotation speed of the electric motor 60. The signal of the motor rotation speed detection value detected by the rotation speed sensor 72 is input to the controller 20.

The turbine 62 is rotationally driven by the combustion gas supplied from the combustor 32. Then, the turbine 62 outputs this rotational driving force to the compressor 64 via the rotational driving shaft 66. That is, the compressor 64 can be directly rotated via the rotary drive shaft 66 by the recovery power of the turbine 62 (hereinafter, also referred to as “turbine recovery power”).

The electric motor 60 may be driven by the recovery power of the turbine 62. Further, the regenerative operation of the electric motor 60 can be performed by driving the electric motor 60 with the recovery power from the turbine 62. Further, the combustion gas after being used for driving the turbine 62 is discharged through the turbine exhaust passage 68.

Further, for example, when the required output to the fuel cell system 100 (hereinafter, also referred to as “system required output”) is high, the target value of the power of the compressor 64 (hereinafter, also referred to as “target compressor power”). Is relatively large, and when it is necessary to increase the turbine recovery power, etc., the flow rate of the combustion gas flowing into the turbine 62 (hereinafter, also referred to as “turbine gas inlet flow rate”), temperature (hereinafter, also referred to as “turbine gas inlet flow rate”), temperature (hereinafter, Then, the “turbine inlet temperature”) and the pressure can be increased to suitably supply power to the compressor 64. Further, by adjusting the nozzle lift amount of the nozzle vane 34 described above, the turbine recovery power can be adjusted by adjusting the pressure of the combustion gas supplied to the turbine 62.

The compressor 64 is connected to the electric motor 60 and the turbine 62 via a rotary drive shaft 66. The compressor 64 is rotationally driven by at least one of the electric motor 60 and the turbine 62 via the rotary drive shaft 66, and sucks air into the fuel cell system 100 from the outside. Then, the compressor 64 supplies the sucked air to the cathode electrode of the fuel cell stack 10 through the cathode gas supply passage 22. Therefore, in the present embodiment, the compressor 64 is driven by the electric motor 60, which is independent of the turbine 62, and the turbine 62.

Next, the heating / cooling mechanism 17 will be described. The heating / cooling mechanism 17 includes a cooling water circulation flow path 80, a heat exchanger 82, and a cooling water circulation pump 84. The heating / cooling mechanism 17 controls the temperature of the cooling water in the cooling water circulation flow path 80 by a cooling device such as a radiator (not shown).

The cooling water circulation flow path 80 is a passage for circulating cooling water between the cooling water inlet 10a and the cooling water outlet 10b of the fuel cell stack 10. That is, the cooling water circulating in the cooling water circulation flow path 80 is supplied into the fuel cell stack 10 from the cooling water inlet 10a of the fuel cell stack 10 and discharged from the cooling water outlet 10b of the fuel cell stack 10. It flows.

Further, a cooling water branch path 86 for supplying cooling water to the hydrogen heater 42 described above is connected to the cooling water circulation flow path 80. Therefore, the hydrogen supplied from the high-pressure tank 40 to the fuel cell stack 10 and the combustor 32 is heated by the cooling water flowing from the cooling water circulation flow path 80 to the cooling water branch path 86.

Further, in the cooling water circulation flow path 80, a water temperature sensor 88 is provided in the vicinity of the cooling water outlet 10b of the fuel cell stack 10. The water temperature sensor 88 detects the temperature of the cooling water discharged from the fuel cell stack 10 (hereinafter, also referred to as “cooling water temperature”). The signal of the cooling water temperature detection value detected by the water temperature sensor 88 is input to the controller 20.

The heat exchanger 82 exchanges heat between the cooling water flowing through the cooling water circulation flow path 80 and the exhaust gas from the turbine bypass passage 39 described above.

The cooling water circulation pump 84 circulates the cooling water in the cooling water circulation flow path 80. The output of the cooling water circulation pump 84 is controlled by the controller 20.

Next, the HFR measuring device 18 will be described. The HFR measuring device 18 functions as a wet state acquisition device for acquiring the wet state of the electrolyte membrane in the fuel cell stack 10. The HFR measuring device 18 is connected to the fuel cell stack 10 and measures the internal impedance of the fuel cell stack 10 that correlates with the wet state of the electrolyte membrane.

In general, the smaller the water content (moisture) of the electrolyte membrane, that is, the drier the electrolyte membrane, the larger the internal impedance. On the other hand, the larger the water content of the electrolyte membrane, that is, the wetter the electrolyte membrane, the smaller the internal impedance. Therefore, in the present embodiment, the internal impedance of the fuel cell stack 10 is used as a parameter indicating the wet state of the electrolyte membrane.

Then, the HFR measuring device 18 supplies, for example, a high-frequency alternating current suitable for detecting the electric resistance of the electrolyte membrane, and divides the amplitude of the output alternating voltage by the amplitude of the alternating current. Calculate the internal impedance.

In the following, the internal impedance (high frequency resistance) calculated based on the high frequency AC voltage and AC current will also be described as HFR (High Frequency Resistance). The HFR measuring device 18 outputs the calculated HFR value as the HFR measured value to the controller 20.

The load device 19 receives and drives the generated electric power supplied from the fuel cell stack 10. Examples of the load device 19 include various auxiliary machines such as a traveling motor for driving a vehicle and an electric motor 60.

The load device 19 outputs the electric power required for its operation to the controller 20 as the required power generation for the fuel cell stack 10.

A current sensor 51 and a voltage sensor 52 are arranged between the load device 19 and the fuel cell stack 10.

The current sensor 51 is connected to a power supply line between the positive electrode terminal of the fuel cell stack 10 and the positive electrode terminal of the load device 19. The current sensor 51 detects the current output from the fuel cell stack 10 to the load device 19. Hereinafter, the current output from the fuel cell stack 10 to the load device 19 is also referred to as a “stack current”. The current sensor 51 outputs a signal of the stack current detection value to the controller 20.

The voltage sensor 52 is connected between the positive electrode terminal and the negative electrode terminal of the fuel cell stack 10. The voltage sensor 52 detects the voltage between terminals, which is the voltage between the positive electrode terminal and the negative electrode terminal. Hereinafter, the voltage between the terminals of the fuel cell stack 10 is referred to as a “stack voltage”. The voltage sensor 52 outputs a signal of the stack voltage detection value to the controller 20.

Further, the fuel cell system 100 configured as described above has a controller 20 as an operation control device that comprehensively controls the operating state of the system.

The controller 20 is composed of a microcomputer including a central arithmetic unit (CPU), a read-only memory (ROM), a random access memory (RAM), and an input / output interface (I / O interface).

A signal from the operating state detection unit of the fuel cell system 100 is input to the controller 20. Specifically, the controller 20 has an HFR measuring device 18, an air flow meter 26, an air pressure sensor 28, a stack outlet temperature sensor 30, a hydrogen pressure detection sensor 47, a current sensor 51, a voltage sensor 52, and a rotation speed as operating state detection units. It has a sensor 72 and a water temperature sensor 88. Then, signals from these are input to the controller 20.

Further, the requested load from the load device 19 in the fuel cell stack 10 is input to the controller 20. In the present embodiment, the load by the load device 19 includes, for example, running power (system required output) based on the amount of operation of the accelerator pedal detected by an accelerator pedal sensor (not shown), electric motor 60, various pumps, valves, and the like. , The electric power consumed by the auxiliary equipment for operating the fuel cell system 100 (auxiliary equipment power consumption) is included.

The controller 20 calculates the required power generation to the fuel cell system 100 based on the required load. That is, the required generated power for the fuel cell stack 10 corresponds to the sum of the system required output such as running power output to the outside of the fuel cell system 100 and the auxiliary power consumption. In this embodiment, which will be described in detail later, the power consumption of the electric motor 60 included in the power consumption of the auxiliary machine is assisted by the recovery power of the turbine 62.

Then, the controller 20 calculates a target stack current, which is a target value of the stack current, from the required generated power based on a predetermined IV characteristic of the fuel cell stack 10.

Based on the above input signals and the like, the controller 20 has a nozzle lift amount of the nozzle vane 34, an opening degree of the bypass valve 38, an opening degree of the stack supply hydrogen pressure regulating valve 48, an opening degree of the combustor hydrogen amount adjusting valve 49, and an electric motor. It controls the output of 60 (torque or power) and the output of the cooling water circulation pump 84.

Hereinafter, the control mode of the fuel cell system 100 according to the present embodiment will be described. In the present embodiment, the terms "power" and "electric power" are used as terms corresponding to "output" without distinguishing them as terms meaning both mechanical energy and electrical energy.

FIG. 2 is a flowchart illustrating an outline of overall control of the fuel cell system 100.

As shown in the figure, in step S100, the controller 20 reads the signal of the required power by the load device 19.

In step S110, the controller 20 calculates the target stack current.

FIG. 3 is a flowchart showing the flow of calculation of the target stack current.

As shown, in step S111, the controller 20 estimates the power consumption of the auxiliary equipment. Specifically, the controller 20 calculates an estimated value of the power consumption of the electric motor 60 from the electric motor rotation speed detection value or the like by the motor rotation speed sensor 72. Further, the power consumption of other actuators such as the cooling water circulation pump 84 and the combustor hydrogen amount control valve 49 or the value obtained by adding the estimated value thereof to the estimated value of the power consumption of the electric motor 60 may be used as the power consumption estimated value of the auxiliary machine. good.

In step S112, the controller 20 calculates the target stack power. Specifically, the target stack power is added by adding the estimated value of the auxiliary power consumption calculated in step S111 to the system required output as the running power based on the operation amount of the accelerator pedal included in the load device 19. Is calculated.

In step S113, the controller 20 calculates the actual stack power. Specifically, the controller 20 calculates the actual stack power by multiplying the stack current detection value by the current sensor 51 and the stack voltage detection value by the voltage sensor 52.

In step S114, the controller 20 calculates the target stack current. Specifically, the controller 20 determines the target stack current so that the actual stack power calculated in step S113 approaches the target stack power calculated in step S112 while referring to the IV characteristics.

Returning to FIG. 2, when the target stack current is calculated in step S110, the cooling system operation amount calculation in step S120, the air system operation amount calculation in step S130, and the fuel system operation amount calculation in step S140 are performed.

FIG. 4 is a flowchart showing the flow of calculation of the cooling system operation amount.

First, in step S121, the controller 20 approaches the target HFR calculated based on the target stack current by the HFR measurement device 18 from the viewpoint of preferably controlling the wet state of the electrolyte membrane of the fuel cell stack 10. As described above, the wet control required target air flow rate and the wet control required target air pressure are calculated.

In step S122, the controller 20 calculates the operation amount of each cooling system actuator. For example, the controller 20 calculates the target radiator fan speed of a radiator (not shown) provided in the cooling water circulation flow path 80 and the target opening degree of the three-way valve 8 (not shown) based on the target HFR or the like.

Next, the flow of calculation of the air system operation amount will be described.

FIG. 5 is a flowchart showing the flow of calculation of the air system operation amount.

As shown in the figure, in step S131, the controller 20 sets a target air pressure, which is a target value of the air pressure, from the target stack current, in consideration of the wetness control required target air pressure, based on a predetermined table. calculate.

In step S132, the controller 20 calculates the target air flow rate, which is the target value of the air flow rate, from the target stack current in consideration of the wetness control required target air flow rate based on the predetermined table.

In step S133, the controller 20 calculates the operation amount of each actuator of the air system. For example, the controller 20 calculates the command nozzle lift amount of the nozzle vane 34 and the command torque of the electric motor 60 based on the target air pressure, the target air flow rate, the air flow rate detection value, the air pressure detection value, and the like.

In step S134, the controller 20 calculates a target turbine inlet temperature, which is a target value of a combustion exhaust gas temperature (turbine inlet temperature) near the inlet of the turbine 62. Specifically, the controller 20 is based on the command torque of the electric motor 60 calculated in step S133, the electric motor rotation speed detection value by the motor rotation speed sensor 72, the target stack current, the target air pressure, the target air flow rate, and the like. Then, the target turbine inlet temperature is calculated.

FIG. 6 is a flowchart showing the flow of calculation of the fuel system operation amount.

As shown in the figure, in step S141, the controller 20 calculates the target supply hydrogen pressure, which is the target value of the hydrogen pressure to be supplied to the fuel cell stack 10 based on the target stack current and the like.

In step S142, the controller 20 is a fuel system actuator such as a target stack supply hydrogen pressure regulating valve opening degree, which is an opening degree target value of the stack supply hydrogen pressure regulating valve 48, and a purge valve opening degree (not shown), based on the target hydrogen supply pressure. Calculate the amount of operation of.

Returning to FIG. 2, in step S150, the controller 20 of the cooling system actuator operation amount calculated in step S120, the operation amount of the air system actuator calculated in step S130, and the fuel system actuator calculated in step S140. The cooling system actuator, the air system actuator, and the fuel system actuator are controlled based on the operation amount.

Further, in the following, the control of the air system of the fuel cell system 100 according to the present embodiment will be described in more detail.

FIG. 7 is a flowchart showing the details of the control of the air system of the present embodiment.

As shown in the figure, in step S210, the controller 20 determines a steady-state operation motor power upper limit value, which is an upper limit value of the motor power in the steady-state operation state (see “Motor output upper limit value setting unit 202” in FIG. 10). Here, in the present embodiment, the "steady operation state" means a state in which the changes in the motor power and the turbine recovery power according to the system required output are almost constant.

More specifically, it means a state in which the turbine recovery power substantially matches the target turbine recovery power or a state in which the motor power is substantially equal to or less than the steady-state target operation motor power upper limit value. That is, in the steady operation state, the motor power excess amount obtained by subtracting the steady-state target operation motor power upper limit value from the motor power is equal to or less than a predetermined value.

FIG. 8 is a flowchart illustrating details of calculation of the steady-state motor power upper limit value.

As shown in the figure, in step S211 the controller 20 acquires the maximum motor power (see “Motor output upper limit value setting unit 202” in FIG. 10). The maximum motor power is, for example, a maximum value of power predetermined as a continuous rating of the electric motor 60 or the like.

In step S212, the controller 20 acquires the maximum power generated by the motor (see “Motor output upper limit setting unit 202” in FIG. 10). The maximum power generation required motor power corresponds to the power to be supplied from the fuel cell stack 10 to the electric motor 60, which is determined based on the target stack current.

As will be described in detail later, in the present embodiment, the controller 20 limits the target motor power by lowering the maximum power generation required motor power in a high load region where the target stack current increases by a predetermined value or more. (See “Motor output upper limit setting unit 202” and FIG. 13 in FIG. 10).

In step S213, the controller 20 acquires the output limit request motor power. The output limit required motor power is the motor power determined by the relationship between the stack output limit value according to the cooling water temperature and wet state of the fuel cell stack 10 and the auxiliary power consumption (other than the power consumption of the electric motor 60) and the system required output. (See the calculation unit B1037 in FIG. 10).

Specifically, the controller 20 calculates the stack output limit value from the temperature required stack current limit value obtained based on the cooling water temperature of the fuel cell stack 10 and the HFR required stack current limit value obtained based on the HFR measurement value. (See FIG. 14 below). Then, the controller 20 calculates the output limit request motor power by subtracting the power consumption of the auxiliary machine (other than the electric motor 60) and the system request output from the stack output limit value (“motor output upper limit value setting unit” in FIG. 10). 202 ”).

In step S134, the controller 20 calculates the minimum value among the acquired maximum motor power, generated power required maximum motor power, and output limit required motor power as the target motor power (steady operation motor power upper limit value) (FIG. 10). Refer to the minimum select section B1038 of.

Returning to FIG. 7, in step S220, the controller 20 calculates the target compressor power.

Specifically, the controller 20 calculates the command nozzle lift amount and the target compressor torque corresponding to the target compressor power so that the air pressure detection value and the air flow rate detection value approach the target air pressure and the target air flow rate, respectively. (See the air system actuator control unit B1033 in FIG. 10).

In the present embodiment, the target compressor torque is the torque required in the compressor 64 determined based on the air pressure and the air flow rate as the operating state of the fuel cell system 100. That is, in the present embodiment, the target compressor torque is a value corresponding to the sum of the target torque of the electric motor 60 and the target torque of the turbine 62. Then, the controller 20 calculates the target compressor power from the calculated target compressor torque (see the calculation unit B1035 in FIG. 10).

In step S230, the controller 20 calculates the target turbine recovery power. Specifically, the controller 20 subtracts the target motor power (steady operation motor power upper limit value) calculated in step S130 from the target compressor power calculated in step S140 (see the calculation unit B1035 in FIG. 10) to achieve the target. The turbine recovery power is calculated (see the subtraction unit 302 in FIG. 10).

In step S240, the controller 20 controls the amount of hydrogen supplied to the combustor 32.

Specifically, the controller 20 calculates the target hydrogen supply valve opening degree, which is the target value of the opening degree of the combustor hydrogen amount control valve 49, based on the target turbine recovery power obtained in step S230 (FIG. 10). Target turbine inlet temperature calculation unit B1039 and combustor hydrogen amount control valve control unit B105 in FIG. 9).

In this embodiment, when calculating the target hydrogen supply valve opening degree, the allowable upper limit temperature determined based on the heat resistance of the parts of the turbine 62 and the like is taken into consideration (see the minimum select unit B104 in FIG. 9 described later). Then, the controller 20 controls the opening degree of the combustor hydrogen amount control valve 49 to the target hydrogen supply valve opening degree (see the combustor hydrogen amount control valve control unit B105 in FIG. 9).

In step S250, the controller 20 calculates the pre-limit motor command torque. Specifically, the controller 20 calculates the estimated turbine recovery torque by dividing the current estimated turbine recovery power (hereinafter, also referred to as "estimated turbine recovery power") by the rotation speed of the electric motor 60 (hereinafter, also referred to as "estimated turbine recovery power"). Calculation unit B1032) in FIG. Then, the controller 20 calculates the pre-limit motor command torque by subtracting the estimated turbine recovery power from the target compressor torque calculated in step S220 (see the subtraction unit 300 in FIG. 10).

In step S260, the controller 20 calculates the motor command torque. Specifically, the controller 20 calculates the smaller of the pre-limit motor command torque calculated in step S250 and the transient operation motor power upper limit value which is the upper limit value of the motor power in the transient operation state as the motor command torque. (See the minimum select section B1034 in FIG. 10). That is, the motor command torque is a value obtained by limiting the pre-limit motor command torque by the transient operation motor power upper limit value.

In the present embodiment, the transient operation state means a state in which the turbine recovery power is lower than a predetermined value or more than the target turbine recovery power, or a state in which the motor power is higher than a predetermined value or more than the steady time target operation motor power upper limit value. To do.

Next, various controls in the fuel cell system 100 according to the present embodiment will be described in detail with reference to the block diagrams shown in FIGS. 9 to 14. The functions of the blocks shown in FIGS. 9 to 14 are realized by the controller 20.

FIG. 9 is a block diagram showing an outline of the overall function of the air system control in the fuel cell system 100.

As shown in the figure, the controller 20 includes a target stack current calculation unit B100, a provisional target air pressure calculation unit B101, a max select unit B101', a provisional target air flow rate calculation unit B102, and a max select unit B102'. It has an air system control unit B103 as a steady state determination unit and an output distribution adjustment unit, a minimum select unit B104, and a combustor hydrogen amount control valve control unit B105 in the embodiment.

As a request from the outside of the fuel cell system 100, the target stack current calculation unit B100 is input with the running power required for the running of the vehicle on which the fuel cell system 100 is mounted. Specifically, the traveling power based on the amount of depression of the accelerator pedal detected by the accelerator pedal sensor (not shown) is input. Further, an estimated value of auxiliary power consumption is input to the target stack current calculation unit B100.

The target stack current calculation unit B100 calculates the target stack power by adding the estimated values of the traveling power and the auxiliary power consumption, and calculates the target stack current according to the processes described in steps S112 to S114 of FIG. To do.

Further, the target stack current calculation unit B100 outputs the calculated target stack current to the provisional target air pressure calculation unit B101, the provisional target air flow rate calculation unit B102, and the air system control unit B103.

The target stack current is input to the provisional target air pressure calculation unit B101. The provisional target air pressure calculation unit B101 calculates the provisional target air pressure from the target stack current before considering the wet state of the electrolyte membrane in the fuel cell stack 10 based on a predetermined map. The provisional target air pressure calculation unit B101 outputs the calculated provisional target air pressure to the max select unit B101'.

The provisional target air pressure and the wet requirement target air pressure are input to the max select unit B101'. The wet requirement target air pressure is a target value of the air pressure determined from the viewpoint of appropriately maintaining the wet state of the electrolyte membrane in the fuel cell stack 10. Then, the max select unit B101'outputs the larger of the provisional target air pressure and the wet requirement target air pressure to the air system control unit B103 as the final target air pressure.

The target stack current is input to the provisional target air flow rate calculation unit B102. The provisional target air flow rate calculation unit B102 calculates the provisional target air flow rate before considering the wet state of the electrolyte membrane in the fuel cell stack 10 from the target stack current based on a predetermined map.

A provisional target air flow rate and a wet requirement target air flow rate are input to the max select unit B102'. The wet requirement target air flow rate is a target value of the air flow rate determined from the viewpoint of appropriately maintaining the wet state of the electrolyte membrane in the fuel cell stack 10. Then, the max select unit B102'outputs the larger of the provisional target air flow rate and the wetness request target air flow rate to the air system control unit B103 as the final target air flow rate.

The air system control unit B103 includes a target stack current, a target air pressure, a target air flow rate, an air flow rate detection value, a target turbine inlet temperature previous value, a motor rotation speed detection value, an air pressure detection value, an HFR measurement value, and a target cooling water. The temperature, cooling water temperature detection value, stack voltage detection value, and system required output are input.

In the present embodiment, the air system control unit B103 controls the output of the electric motor 60 and the turbine recovery power based on these input values. Specifically, the air system control unit B103 calculates the command nozzle lift amount and the motor command torque based on each input value, feedback-controls the torque of the electric motor 60 and the nozzle vane opening, and also controls the pre-limit target. The turbine inlet temperature is calculated and output to the minimum select unit B104.

FIG. 10 is a block diagram showing a detailed function of the air system control unit B103. As shown in the figure, the air system control unit B103 includes a turbine recovery power estimation unit B1031, a calculation unit B1032, an air system actuator control unit B1033, a minimum select unit B1034, a calculation unit B1035, and a motor output upper limit value setting unit. It has 202 and a target turbine inlet temperature calculation unit B1039.

The air pressure detection value, the air flow rate detection value, and the target turbine inlet temperature previous value are input to the turbine recovery power estimation unit B1031. The turbine recovery power estimation unit B1031 calculates an estimated value of turbine recovery power (hereinafter, also referred to as “estimated turbine recovery power”) from these values and the previous value of the turbine inlet temperature stored in a storage unit (not shown).

Specifically, first, the turbine recovery power estimation unit B1031 obtains an estimated value Tt _{_in_e} of the turbine inlet temperature by using the approximation formula (1) of the temporary delay in the discrete system shown below.

ただし、
Ｔｔ_{_in_e}(ｎ−1)：タービン入口温度前回値 [℃]
Ｔｔ_{_in_t}：目標タービン入口温度前回値 [℃]
ｔｓ：時定数 [sec]
ｔ_samp：制御演算周期 [sec]
である。なお、時定数ｔｓは、実験等により予め定められる。

However,
Tt _{_in_e} (n−1): Turbine inlet temperature previous value [° C]
Tt _{_in_t} : Target turbine inlet temperature Previous value [℃]
ts: Time constant [sec]
t _samp : Control calculation cycle [sec]
Is. The time constant ts is predetermined by an experiment or the like.

Then, the turbine recovery power estimation unit B1031 calculates the estimated turbine recovery power from the estimated turbine inlet temperature. Specifically, the turbine recovery power estimation unit B1031 calculates the estimated turbine recovery power PO _{t_e} based on the following equation (2).

ただし、
ＰＯ_{t_e}：推定タービン回収動力 [kW]
Ｑ_in：空気流量検出値 [NL/min]
Ｍ_air：空気の式量 [g/mol]
ｃｐ_air：空気の定圧比熱 [kJ/(g・K)]
Ｖ_sta：標準状態における体積（＝２２．４１４） [L]
η_cp：タービン効率
Ｔ_{t_in_e}：タービン入口温度の推定値[℃]
Ｔ_sta：標準状態における絶対温度（＝２７３．１５） [K]
Ｐ_{t_in}：タービン入口空気圧力 [kPa＿a]
Ｐ_{t_out}：タービン出口空気圧力 [ｋPa_a]
γ：比熱比
６０：秒分間の単位変換係数
１０００：ｍ³とＬ（リットル）の単位変換係数
である。

However,
PO _{t_e} : Estimated turbine recovery power [kW]
Q _in : Air flow rate detection value [NL / min]
M _air : Formula amount of air [g / mol]
cp _air : Constant pressure specific heat of air [kJ / (g ・ K)]
V _sta : Volume in standard state (= 22.414) [L]
η _cp : Turbine efficiency T _{t_in_e} : Estimated turbine inlet temperature [° C]
T _sta : Absolute temperature under standard conditions (= 273.15) [K]
P _{t_in} : Turbine inlet air pressure [kPa_a]
P _{t_out} : Turbine outlet air pressure [kPa_a]
γ: Specific heat ratio 60: Unit conversion coefficient for seconds and minutes 1000: Unit conversion coefficient of m ³ and L (liter).

The turbine inlet air pressure Pt _{_in} is calculated based on the air pressure detection value and the air flow rate detection value.

FIG. 11 is a block diagram showing a calculation function of the turbine inlet air pressure Pt _{_in} . The turbine recovery power estimation unit B1031 has a pressure loss calculation block B301 and a calculation unit B302 shown in the figure as functions for calculating the turbine inlet air pressure Pt _{_in} .

An air flow rate detection value is input to the pressure drop calculation block B301. The pressure drop calculation block B301 has a pressure loss map showing the relationship between the air flow rate and the pressure loss ΔP. The pressure loss calculation block B301 calculates the pressure loss ΔP of the fuel cell stack 10 from the input air flow rate detection value based on this pressure loss map, and outputs it to the calculation unit B302.

The air pressure detection value and the pressure loss ΔP are input to the calculation unit B302. The calculation unit B302 subtracts the pressure loss ΔP from the air pressure detected value to obtain the turbine inlet air pressure Pt _{_in} .

As the turbine outlet air pressure Pt _{_out} , for example, atmospheric pressure ( _≈101 [kpa]) is used. When the pressure of the outside air fluctuates, the pressure detection value detected by the atmospheric pressure sensor (not shown) may be used as the turbine outlet air pressure Pt _{_out} .

Turbine efficiency η _cp is calculated based on the turbine inlet air pressure Pt _{_in} and the turbine outlet air pressure Pt _{_out} .

FIG. 12 is a block diagram showing a calculation function of the turbine efficiency η _cp . The turbine recovery power estimation unit B1031 has a calculation unit B401 shown in the figure and a turbine efficiency calculation block B402 as functions for calculating the turbine efficiency η _cp .

Turbine inlet air pressure Pt _{_in} and turbine outlet air pressure Pt _{_out} are input to the calculation unit _B401 . The calculation unit _B401 calculates the air pressure ratio Pt _{_in} / Pt _{_out} and outputs the turbine efficiency calculation block _B402 .

The air pressure ratio Pt _{_in} / Pt _{_out} is input to the turbine efficiency calculation block _B402 . The turbine efficiency calculation block _B402 has a turbine efficiency map showing the relationship between the air pressure ratio Pt _{_in} / Pt _{_out} and the turbine efficiency η _cp . The turbine efficiency calculation block _B402 calculates the turbine efficiency η _cp from the input air pressure ratio Pt _{_in} / Pt _{_out} based on this turbine efficiency map.

Returning to FIG. 10, the turbine recovery power estimation unit B1031 outputs the calculated estimated turbine recovery power to the calculation unit B1032.

The estimated turbine recovery power and the motor rotation speed detection value from the rotation speed sensor 72 are input to the calculation unit B1032. The calculation unit B1032 divides the motor rotation speed detection value from the estimated turbine recovery power, and obtains an estimated value of turbine recovery torque (hereinafter, also referred to as "estimated turbine recovery torque"), which is the torque recovered by the turbine 62. calculate. Then, the calculation unit B1032 outputs the calculated estimated turbine recovery torque to the subtraction unit 300.

The target air pressure, the target air flow rate, the air pressure detection value, and the air flow rate detection value are input to the air system actuator control unit B1033. The air system actuator control unit B1033 calculates the command nozzle lift amount and the target compressor torque so that the input air pressure detection value and the air flow rate detection value approach the target air pressure and the target air flow rate, respectively.

Further, the air system actuator control unit B1033 outputs the calculated command nozzle lift amount to the nozzle vane 34, and outputs the calculated target compressor torque to the subtraction unit 300 and the calculation unit B1035.

The subtraction unit 300 subtracts the estimated turbine recovery torque calculated by the calculation unit B1032 from the target compressor torque calculated by the air system actuator control unit B1033, and outputs the subtraction unit 300 to the minimum select unit B1034.

Then, the pre-limit motor command torque and the transient motor torque upper limit value are input to the minimum select unit B1034. Here, the pre-limit motor command torque is a value obtained by subtracting the estimated turbine recovery torque from the target compressor torque in the subtraction unit 300.

Further, the transient motor torque upper limit value is a value set as the maximum motor torque that the power of the electric motor 60 can reach when the fuel cell system 100 is in the transient operation state, and is stored in advance in the storage unit 301. Has been done. The transient motor torque upper limit value is a so-called short-time rating set according to, for example, the specifications of the electric motor 60.

Then, the minimum select unit B1034 outputs the smaller of the pre-limit motor command torque and the transient motor torque upper limit value to the electric motor 60 as the motor command torque.

The target compressor torque calculated by the air system actuator control unit B1033 and the motor rotation speed detection value are input to the calculation unit B1035. The calculation unit B1035 calculates the target compressor power by multiplying the target compressor torque by the motor rotation speed detection value. The calculation unit B1035 outputs the target compressor power to the subtraction unit 302.

The motor output upper limit value setting unit 202 in the present embodiment sets the motor output upper limit value, which is the output upper limit value of the electric motor 60 in the above-mentioned steady operation state.

Specifically, the motor output upper limit value setting unit 202 includes a generated power request maximum motor power calculation unit B1036, a stack output limit value calculation unit 203, a calculation unit B1037, a minimum select unit B1038, and a target turbine inlet temperature calculation unit. It has B1039 and.

The target stack current is input to the generated power request maximum motor power calculation unit B1036. The generated power required maximum motor power calculation unit B1036 calculates the generated power required maximum motor power from the target stack current based on a predetermined generated power required maximum motor power map.

FIG. 13 shows an outline of the maximum power generation required motor power map. In the map shown in the figure, the maximum power generation required motor power map is set to a constant value until the target stack current increases and reaches the predetermined value I1, that is, in the low to medium load region where the system required output is relatively low. There is. As a result, when the system required output is relatively low, the required power to the compressor 64 is lower than the target motor output, the target turbine recovery power becomes negative, and the fuel supply to the combustor 32 is stopped.

On the other hand, after the target stack current reaches the predetermined value I1, that is, in the high load region where the system required output is relatively high, the generated power required maximum motor power decreases. This is because the target turbine recovery power is relatively increased in a state where the system required output is relatively high, the maximum generated power required motor power is reduced, and the power consumption of the electric motor 60 is further reduced. Thereby, the system output of the fuel cell system 100 obtained by subtracting the electric power consumed by the auxiliary machinery including the electric motor 60 from the generated electric power of the fuel cell stack 10 can be improved.

Returning to FIG. 10, the generated power required maximum motor power calculation unit B1036 outputs the calculated generated power required maximum motor power to the minimum select unit B1038.

FIG. 14 is a block diagram showing the configuration of the stack output limit value calculation unit 203.

As shown in the figure, the stack output limit value calculation unit 203 includes a temperature request stack current limit value calculation unit B501, an HFR request current limit value calculation unit B502, a minimum select value calculation unit B503, and a calculation unit B504. There is.

The target cooling water temperature and the cooling water temperature detection value are input to the temperature request stack current limit value calculation unit B501. The temperature request stack current limit value calculation unit B501 calculates the limit value of the stack current calculated so that the deviation between the cooling water temperature detection value and the target cooling water temperature is equal to or less than a predetermined value as the temperature request stack current limit value.

The HFR measurement value is input to the HFR required current limit value calculation unit B502. The HFR request current limit value calculation unit B502 calculates the HFR request stack current limit value from the HFR measurement value based on a predetermined HFR-current limit value map.

In the HFR-current limit value map shown in the figure, the larger the HFR measurement value (the drier the electrolyte membrane), the smaller the HFR required stack current limit value. This is to reduce the current taken out from the fuel cell stack 10 from the viewpoint of preventing deterioration of the electrolyte membrane when the electrolyte membrane dries.

On the other hand, when the HFR value is relatively low (the wetness of the electrolyte membrane is relatively high), a larger amount of current can be taken out from the fuel cell stack 10, so that the HFR required stack current limit value is relative. Becomes larger.

The temperature required stack current limit value and the HFR required stack current limit value are input to the minimum select unit B503. The minimum select unit B503 outputs the smaller of these values to the calculation unit B504 as the stack current limit value.

The stack current limit value and the stack voltage limit value are input to the calculation unit B504. The calculation unit B504 calculates the stack output limit value by multiplying these values with each other, and outputs the stack output limit value to the calculation unit B1037.

Returning to FIG. 10, the stack output limit value, auxiliary power consumption, and system request output are input to the calculation unit B1037. Here, the power consumption of auxiliary equipment is the power consumption of auxiliary equipment (for example, various valves, pumps, etc.) other than the electric motor 60 in the fuel cell system 100.

The calculation unit B1037 subtracts the auxiliary power consumption other than the electric motor 60 and the system required output from the stack output limit value, and calculates as the output limit request motor power. The calculation unit B1037 outputs the calculated output limit request motor power to the minimum select unit B1038.

The maximum motor power, the maximum generated power required motor power, and the output limit required motor power are input to the minimum select unit B1038. The minimum select unit B1038 outputs the minimum value among these values to the subtraction unit 302 as the target motor power.

That is, in the present embodiment, the minimum value among the maximum motor power, the maximum generated power required motor power, and the output limit required motor power is set as the target motor power which is the target value of the power of the electric motor 60. Therefore, in the present embodiment, the target motor power corresponds to the steady-time target operation motor power upper limit value.

In the target turbine inlet temperature calculation unit B1039, a value obtained by subtracting the target motor power from the target compressor power in the subtraction unit 302 is input as the target turbine recovery power. Therefore, in the present embodiment, the target turbine recovery power is calculated as the amount that the power obtained by the electric motor 60 is insufficient for the power required by the compressor 64.

Further, the target air pressure and the target air flow rate are input to the target turbine inlet temperature calculation unit B1039.

Then, the target turbine inlet temperature calculation unit B1039 calculates the target turbine inlet temperature before the limit based on the target turbine recovery power, the target air pressure, and the target air flow rate. Here, the target turbine inlet temperature before the limit is also the target value of the turbine inlet temperature before the limit is applied in consideration of the heat resistant temperature of the parts of the turbine 62 described later.

The target turbine inlet temperature calculation unit B1039 specifically uses the equation (2) used in the turbine recovery power estimation unit B1031 to obtain the target turbine inlet temperature before the limit from the target turbine recovery power, the target air pressure, and the target air flow rate. Is calculated.

That is, the target turbine recovery power is substituted for PO _{t_e} in Eq. (2), and the target air flow rate is substituted for Q _in . Then, in the calculation logic of the turbine inlet air pressure P _{t_in} shown in FIG. 11, the “air pressure detection value” and the “air flow rate detection value” are replaced with the target air pressure and the target air flow rate, respectively, and the turbine inlet air pressure P _{Calculate t_in} . Atmospheric pressure is used as the turbine outlet air pressure P _{t_out} . By applying each value thus obtained to the equation (2), the T _{t_in_e} of the equation (2) can be obtained, and this can be set as the target turbine inlet temperature before restriction.

The target turbine inlet temperature calculation unit B1039 outputs the calculated target turbine inlet temperature before the limit to the minimum select unit B104.

Returning to FIG. 9, the minimum pre-limit turbine inlet temperature and the allowable upper limit temperature output from the air system control unit B103 are input to the minimum select unit B104. Here, the allowable upper limit temperature is an upper limit temperature of the turbine inlet temperature determined in consideration of the heat resistant temperature of the component, and is stored in advance in the storage unit 303.

The minimum select unit B104 outputs the smaller value of the pre-limit target turbine inlet temperature and the allowable upper limit temperature to the combustor hydrogen amount control valve control unit B105 as the target turbine inlet temperature.

The target turbine inlet temperature, air flow rate detection value, air pressure detection value, stack outlet temperature, stack current detection value, supply hydrogen pressure, and cooling water temperature (hydrogen temperature) are input to the combustor hydrogen amount control valve control unit B105. Will be done.

The combustor hydrogen amount control valve control unit B105 calculates the target hydrogen supply valve opening degree, which is the target value of the opening degree of the combustor hydrogen amount control valve 49, based on each input value, and adjusts the combustor hydrogen amount. Output to valve 49. Specifically, the combustor hydrogen amount control valve control unit B105 targets the target turbine inlet temperature, the target air flow rate, and the opening degree of the combustor hydrogen amount control valve 49 based on a predetermined map. The target hydrogen supply valve opening degree of the combustor hydrogen amount control valve 49 is calculated from the turbine inlet temperature and the target air flow rate.

The operating state of the fuel cell system 100 having the control configuration described above will be described.

FIG. 15 shows changes in each parameter of the fuel cell system 100 according to the system required output. Specifically, FIG. 15A shows changes in the net output of the system, and FIG. 15B shows changes in motor power consumption and turbine recovery power. Further, FIGS. 15 (c), 15 (d), and 15 (e) show changes in system efficiency, changes in turbine inlet temperature, and hydrogen supply amount to the combustor 32, respectively. Further, the alternate long and short dash line in FIG. 15B indicates the upper limit value of the steady-time target motor power.

Further, in FIGS. 15A to 15E, it is assumed that the steady-state target motor power upper limit value is not reduced in a high load region where the target stack current is a predetermined value I1 or more and the system required output is relatively high. The change of each amount is shown by a broken line.

As shown in the figure, in the low load region where the stack current is a predetermined value I0 or less and the system required output is relatively low, the combustor 32 is not operating and the turbine inlet temperature and the opening degree of the combustor hydrogen amount control valve 49 are opened. Has a constant value (see FIGS. 15 (d) and 15 (e)). Therefore, the turbine recovery power is relatively small, and the ratio of the power of the compressor 64 to be covered by the motor power consumption is high, so that the system efficiency is relatively high (see FIGS. 15 (b) and 15 (c)).

In the medium load region where the stack current is a predetermined value I0 to I1, the motor power is settled at the upper limit value of the target motor power (upper limit value of the steady target operation motor power) shown by the one-point chain line in the figure, and rises further. It disappears. On the other hand, if the system required output continues to increase even if the increase in motor power stops, the target compressor power will increase. Therefore, in order to satisfy this target compressor power, the combustor 32 is operated to raise the temperature of the combustion gas, the turbine recovery power is improved, and the power of the compressor 64 covered by the turbine 62 is increased.

Next, in the high load region where the stack current is a predetermined value I1 or more, the upper limit value of the steady-time target operation motor power is set to a value lowered according to the logic of the generated power required maximum motor power calculation unit B1036 in FIG. (See FIG. 15 (b)). Along with this, the motor power decreases toward the lowered steady-state target operation motor power upper limit value. Further, in order to compensate for this decrease in motor power with turbine recovery power, the amount of hydrogen supplied to the combustor 32 is further increased to further increase turbine recovery power (FIGS. 15 (b), (d), and (e). )reference).

Therefore, the net output of the system 100 can be further increased while reducing the motor power (motor power consumption) in the high load region (see FIG. 15A). That is, in the fuel cell system 100 according to the present embodiment, the turbine recovery power can be further improved in the high load region, the motor power consumption can be significantly reduced, and the system output can be improved, so that the size of the fuel cell stack 10 can be improved. Can be miniaturized.

FIG. 16 is a time chart showing an example of the flow over time in the control of the fuel cell system 100 of the present embodiment.

As shown in the figure, in the fuel cell system 100 of the present embodiment, at time t1 to t2, the turbine recovery power substantially matches the target turbine recovery power (steady operation state), and the stack current is relatively low. This is a low load region where the required output is small (see FIG. 16A). Further, at times t1 to t2, the motor power is below the steady-state target motor power upper limit value. That is, the amount of excess power obtained by subtracting the target motor power upper limit value at steady time from the motor power is a negative value.

In this steady operation state and low load region, the motor power is not insufficient, the turbine recovery power substantially matches the target turbine recovery power, and the combustor 32 is in a non-operating state. Therefore, the turbine recovery power and the turbine inlet temperature have relatively low values (see FIGS. 16 (c) and 16 (f)).

Next, at time t2, the load (stack current) of the fuel cell stack 10 begins to increase (see FIG. 16A). That is, the system required output to the fuel cell stack 10 begins to increase. Therefore, the air pressure and the air flow rate increase as the load on the fuel cell stack 10 increases (see FIGS. 16 (c) and 16 (d)). Then, as the load increases, the combustor 32 operates, and the turbine inlet temperature and the turbine recovery power start to increase (see FIGS. 16 (c) and 16 (f)).

At time t3, the target turbine recovery power exceeds the turbine recovery power, and the motor power shifts to a transient operation state exceeding the steady-time target motor power upper limit value (see FIGS. 16B and 16C). As shown by the alternate long and short dash line in FIG. 16B, in the transient operation state, the transient target motor power upper limit value larger than the steady state target motor power upper limit value (see “Transient target motor torque maximum value” in FIG. 10). Up to, the increase in motor power is allowed.

On the other hand, according to the map of the generated power demand maximum motor power calculation unit B1036 of FIG. 10, a smaller value is set as the steady target motor power upper limit value (see FIG. 16B). Therefore, the motor power will be limited to lower values. Along with this, the target turbine recovery power is set to a higher value in order to increase the turbine recovery power (see FIG. 16C).

On the other hand, as shown by the broken line in FIG. 16 (c), the target turbine recovery power is set high after time t3, but the actual turbine recovery power has a time lag before reaching the target turbine recovery power due to the response delay. Occurs. Therefore, in the present embodiment, as described above, after the time t3, the transient target motor power upper limit value larger than the steady state target motor power upper limit value is set as the upper limit value of the motor power. As a result, the motor power is allowed to rise beyond the steady-time target motor power upper limit value as the load increases, and the shortage of turbine recovery power due to the response delay is compensated.

At time t4, the motor power becomes maximum (see FIG. 16B), and the load on the fuel cell stack 10 becomes maximum. That is, the system requirement output is maximized (see FIG. 16A). After that, statically indeterminate until time t6 with the maximum load. Further, the turbine recovery power gradually increases toward the target turbine recovery power (see FIG. 16C). On the other hand, according to the control logic of the motor output upper limit value setting unit 202 of FIG. 10, since the target motor power is limited to the steady target motor power upper limit value, the motor power decreases toward the steady target motor power upper limit value ( See FIG. 16 (b)). That is, in securing the power of the compressor 64, the ratio of the turbine recovery power becomes higher than the ratio of the power of the electric motor 60.

At time t5, the motor power and the turbine recovery power are settled at the steady target motor power upper limit value and the target turbine recovery power, respectively (see FIGS. 16 (b) and 16 (c)). That is, the state of the fuel cell system 100 shifts to the steady operation state. Here, in the steady operation state between the times t5 to t6, since the lowered steady target motor power upper limit value is set, the motor power is limited to the lowered steady target motor power upper limit value. , This limit of motor power will be supplemented by turbine recovery power. That is, in securing the power of the compressor 64, the ratio of the turbine recovery power is further higher than the ratio of the power of the electric motor 60.

At time t6, the load begins to decrease (see FIG. 16A), and the required motor power and target turbine recovery power decrease in accordance with the decrease in load. Then, in the present embodiment, the steady-state target motor power upper limit value is returned to the value before the decrease (before the time t3) at the time t6.

Further, since the air pressure and the air flow rate decrease as the load decreases (see FIGS. 16 (d) and 16 (e)), the turbine recovery power decreases and the target turbine recovery power is settled (FIG. 16). (C). On the other hand, the turbine inlet temperature gradually decreases with a slight delay after the combustor 32 is inactive, and is settled at the target turbine inlet temperature at time t7 (see FIG. 16 (f)).

At times t8 to t10, the load on the fuel cell stack 10 is increased again (see FIG. 16A). Further, at time t9, the state of the fuel cell system 100 shifts to the transient operation state. At these times t8 to t10, the load increase amount (system required output) is smaller than at the above-mentioned times t2 to t4.

Therefore, time t10 to time t12 are medium load regions. Here, at time t3 before shifting to the high load region, the steady-state target motor power upper limit value was set to a lower value, but in the medium load region (time t10 to t12), the steady-state target motor power upper limit value was set. It remains maintained without diminishing. Therefore, as is clear from FIG. 16B, when compared with the time t4 to the time t5, which was in the high load region, the motor power value is statically set to the steady-time target motor power upper limit value in which the motor power value does not decrease at the time t11. Will be done. Therefore, while the motor power is maintained relatively high, the turbine recovery power is set to a relatively low value (see FIG. 16 (c)).

As described above, when the system required output is not so high, the ratio of the power of the electric motor 60 to the turbine recovery power to the power supplied to the compressor 64 is increased as compared with the case of the high load region. System efficiency can be improved. That is, in the medium load region where it is considered that a large load is not applied to the fuel cell stack 10, the generated power of the fuel cell stack 10 is extremely large even if the ratio of the power of the electric motor 60 is relatively high. Therefore, the ratio of the power of the electric motor 60 is rather increased from the viewpoint of improving the system efficiency.

According to the fuel cell system 100 and the control method of the fuel cell system 100 according to the first embodiment of the present invention described above, the following effects are exhibited.

The fuel cell system 100 according to the present embodiment includes a high-pressure tank 40 as a fuel supply device for supplying fuel (hydrogen) to the anode electrode of the fuel cell stack 10 as a fuel cell, a hydrogen supply passage for stack 44, and a stack supply hydrogen adjustment. A pressure valve 48, an oxidant supply device that supplies air as an oxidant to the cathode electrode of the fuel cell stack 10, an HFR measuring device 18 as an operating state detection unit that detects the operating state of the fuel cell stack 10, and an air flow meter 26. , Air pressure sensor 28, stack outlet temperature sensor 30, current sensor 51, and voltage sensor 52, and a controller 20 as an operation control device that controls the fuel supply device and the oxidant supply device by signals from the operation state detection unit. And.

In the fuel cell system 100, the oxidant supply device includes a compressor 64 and an electric motor 60 for driving the compressor 64. Then, the controller 20 has an air system control unit B103 as a steady state determination unit for determining whether or not the system is in a steady operation state, and an output upper limit value of the electric motor 60 based on the determination result by the steady state determination unit. It functions as a motor output upper limit value setting unit 202 (see FIG. 10) for setting a steady-state target motor power upper limit value (see FIG. 16B).

Thereby, the output of the electric motor 60 can be limited to the steady state target motor power upper limit value or less depending on whether or not the fuel cell system 100 is in the steady operation state. Therefore, the power consumption of the electric motor 60 can be reduced in the fuel cell system 100, and the size of the electric motor 60 can be reduced. As a result, it contributes to the miniaturization of the entire fuel cell system 100.

In particular, in the present embodiment, since the power consumption of the electric motor 60 can be reduced as described above, the output of the fuel cell stack 10 that supplies power to the electric motor 60 is also reduced, and the stack size is reduced. be able to. As a result, both the electric motor 60 and the fuel cell stack 10 can be miniaturized, which can further contribute to the miniaturization of the fuel cell system 100 as a whole.

Further, in the present embodiment, a turbine 62 that drives the compressor 64 independently of the electric motor 60, and a combustor 32 that burns hydrogen and air (oxygen) to generate combustion gas for driving the turbine 62. , Further prepared. Then, the controller 20 controls the air system as an output distribution adjusting unit that adjusts the motor output, which is the output of the electric motor 60, and the output distribution of the turbine recovery power according to the required load (target stack current) on the fuel cell stack 10. Target turbine inlet temperature calculation unit B1039 and combustor hydrogen amount control valve as a fuel supply control unit that controls the fuel supply amount to the combustor 32 based on the turbine recovery power defined by the unit B103 and the air system control unit B103. A control unit B105 is further provided.

Thereby, in satisfying the required load on the fuel cell stack 10, the ratio of the power obtained by the electric motor 60 and the recovered power of the turbine 62 can be suitably adjusted. In particular, as a result of the output distribution adjustment, the fuel supply amount to the combustor 32 can be suitably controlled based on the required turbine recovery power.

Further, in the fuel cell system 100, in the air system control unit B103 as the output distribution adjustment unit, the difference between the motor output and the steady-time target motor power upper limit value (motor power excess amount in FIG. 16B) is equal to or less than a predetermined value. The turbine recovery power is adjusted so as to be (the motor output upper limit value setting unit 202 and the subtraction unit 302 in FIG. 10).

Thereby, the turbine recovery power can be suitably adjusted so that the motor output does not exceed the target motor power upper limit value at the steady state. Therefore, even in a situation where the motor output is limited to the target motor power upper limit value in the steady state, the load requirement can be satisfied more reliably.

Further, in the fuel cell system 100 of the present embodiment, the air system control unit B103 as the output distribution adjustment unit calculates the target compressor power based on the required load (target stack current) on the fuel cell, and the target compressor power. The target turbine recovery power is calculated by subtracting the steady-time target motor power upper limit value from (see the subtraction unit 302 in FIG. 10). Further, the target turbine inlet temperature calculation unit B1039 and the combustor hydrogen amount control valve control unit B105 as the fuel supply control unit are targets which are target values of the fuel supply amount to the combustor 32 based on the adjusted turbine recovery power. The target hydrogen supply valve opening corresponding to the fuel supply amount is calculated, and the fuel supply amount to the combustor 32 (opening of the combustor hydrogen amount control valve 49) is controlled based on the calculated target hydrogen supply valve opening. To do.

Thereby, the turbine recovery power can be adjusted by adjusting the hydrogen supply amount to the combustor 32 while limiting the motor output so as not to exceed the steady-time target motor power upper limit value with respect to the target compressor power. That is, the amount of hydrogen supplied to the combustor 32 can be adjusted so that the shortage is compensated by the turbine recovery power while limiting the motor output to a relatively low value with respect to the target compressor power. Therefore, since the motor output can be made relatively low with respect to the power required by the compressor 64, the maximum value of the power consumption of the electric motor 60 can be further suppressed, and the electric motor 60 and the fuel cell stack 10 can be further reduced. It is possible to reduce the size.

Further, in the present embodiment, the steady operation state means that the motor output excess amount (motor power excess amount), which is the value obtained by subtracting the steady-time target motor power upper limit value from the output of the electric motor 60, is equal to or less than a predetermined value (substantially zero). ) (In particular, see time t5 to t6 and time t11 to time t12 in FIG. 16B).

Such a steady operation state of the fuel cell system 100 corresponds to a state in which the turbine recovery power substantially matches the target turbine recovery power. Therefore, the target motor power upper limit value in the steady state can be set in a more appropriate scene.

Further, in the fuel cell system 100 of the present embodiment, the controller 20 further includes a system requirement output calculation unit 200 for calculating the system requirement output. Then, the motor output upper limit value setting unit 202 sets the steady-time target motor power upper limit value in consideration of the system required output (see FIG. 10).

As a result, the target motor power upper limit value in the steady state can be set more appropriately according to the magnitude of the system required output.

Further, the system requirement output calculation unit 200 calculates the system requirement output based on the operation amount of the accelerator pedal of the vehicle (see the system requirement output calculation unit of FIG. 9).

As a result, the system required output can be calculated according to the load state of the vehicle equipped with the fuel cell system 100. That is, the load state of the vehicle such as the high load region where the accelerator pedal depression amount is relatively large and the low / medium load region where the accelerator pedal depression amount is relatively small is detected more reliably, and according to the load condition. The control according to the present embodiment can be more preferably executed.

Further, the motor output upper limit value setting unit 202 as the motor output upper limit value setting unit 202 sets the steady-time target motor power upper limit value low when the system required output is relatively high (the maximum generated power request in FIG. 10). Refer to the motor power calculation unit B1036, the calculation unit B1037, and the region where the target stack current in FIGS. 13 and 15 is I1 or more).

As a result, even in a high load region where the system required output is relatively high, the motor power that contributes to the required power of the compressor 64 can be reduced, and the motor power consumption can be further reduced (FIG. 16 (FIG. 16). b) Time t4 to Time t6). As a result, the motor power can be reduced in the high load region. Therefore, the output of the electric motor 60 can be made smaller to further reduce the size of the electric motor 60.

Further, in the present embodiment, the ratio of the electric power consumed by the electric motor 60 to the generated electric power of the fuel cell stack 10 can be further reduced. Therefore, the system output (net output) per generated power of the fuel cell stack 10 can be further improved, so that the size of the fuel cell stack 10 can be further reduced.

Further, in the fuel cell system 100 according to the present embodiment, the motor output upper limit value setting unit 202 as the motor output upper limit value setting unit 202 has the cooling water temperature detected by the water temperature sensor 88 as the operation state detection unit, and the HFR. Based on the HFR measurement value detected by the measuring device 18, the stack output limit value as the output limit value of the fuel cell stack 10 is calculated (stack output limit value calculation unit 203), and the calculated stack output limit value and the system request The output is compared (calculation unit B1037 in FIG. 10). Then, the motor output upper limit value setting unit 202 sets the steady-time target motor power upper limit value lower as the system required output is larger than the stack output limit value (calculation unit B1037 and minimum select unit B1038 in FIG. 10).

As a result, when the difference between the stack output limit value and the system required output according to the operating state of the fuel cell stack 10 is small, that is, most of the upper limit power that can be generated in the fuel cell stack 10 is used as the system output (vehicle running, etc.). When it is necessary to use it, the electric power supplied to the electric motor 60 can be reduced by lowering the target motor power upper limit value in the steady state. Therefore, a larger proportion of the stacked power generation can be used for the system output as needed based on the operating state of the fuel cell stack 10.

Regarding the stack output limit value, in addition to the operating state of the fuel cell stack 10, a limit value according to the size of the fuel cell stack 10 may be added. Specifically, for example, the stack output that is actually used by selecting the smaller of the stack output limit value calculated based on the operating state of the fuel cell and the limit value according to the size of the fuel cell stack 10. It can be a limit value.

Further, in the present embodiment, even when the upper limit value of the target motor power in the steady state is lowered to limit the output of the electric motor 60, this can be supplemented by the turbine recovery power, and the target compressor power can be secured more reliably.

Further, in the fuel cell system 100 according to the present embodiment, the motor output upper limit value setting unit 202 is set based on the maximum motor power which is the continuous rated power of the electric motor 60 and the required load (target stack current) of the fuel cell stack 10. The smallest value among the generated power required maximum motor power as the load required maximum motor power and the stack output limit value is set as the steady-time target motor power upper limit value.

As a result, the maximum motor power such as the continuous rating of the electric motor 60, the required maximum motor power according to the required generated power, and the output limit value according to the operating state of the fuel cell stack 10 are all satisfied. It is possible to set a constant target motor power upper limit value. Therefore, the power consumption of the electric motor 60 can be suitably limited according to these three factors.

As described above, the present embodiment provides a control method for the fuel cell system 100 in which the electric motor 60 drives the compressor 64 that supplies air to the cathode electrode of the fuel cell stack 10. Then, in this control method, the controller 20 determines whether or not the system 100 is in a steady operation state (air system control unit B103 in FIG. 10), and based on the determination result of whether or not the system 100 is in a steady operation state. The output upper limit value of the electric motor is set (motor output upper limit value setting unit 202 in FIG. 10).

Thereby, the output of the electric motor 60 can be limited to the steady state target motor power upper limit value or less depending on whether or not the fuel cell system 100 is in the steady operation state. Therefore, the power consumption of the electric motor 60 can be reduced in the fuel cell system 100, and the size of the electric motor 60 can be reduced. As a result, it contributes to the miniaturization of the entire fuel cell system 100.

Although the embodiments of the present invention have been described above, the above embodiments are only a part of the application examples of the present invention, and the technical scope of the present invention is limited to the specific configurations of the above embodiments. Absent.

For example, in FIG. 16 of the present embodiment, the upper limit value of the steady state target motor power is lowered at time t3 before the time t5 when the steady operation state and the high load occur, but the time when the steady operation state and the high load occur. The upper limit of the steady-state target motor power may be lowered according to t5. Further, before time t5, for example, when the motor power excess amount becomes a predetermined value of 0 or more and a predetermined value or less, the steady state target motor power upper limit value may be set low.

Further, in the present embodiment, as shown in FIG. 16, the value is substantially constant with respect to the time change, except that the steady-state target motor power upper limit value takes a value lowered from time t4 to time t5. .. However, for example, the steady-state target motor power upper limit value may be continuously decreased (increased) according to the continuous increase (decrease) of the system required output.

Further, in the above embodiment, the transient upper limit value of the motor torque uses a short-time rating predetermined according to the specifications of the electric motor 60 and the like, but the present invention is not limited to this, and is suitable as the maximum value of the motor torque. Various values can be used.

As an example, the upper limit of the transient motor torque is set to the temperature of the electric motor 60, the temperature of the inverter (not shown) of the electric motor 60, the short-time rating, and the power of the electric motor 60 is equal to or higher than the target motor power (steady operation motor power upper limit). It may be a fixed value or a variable value obtained based on the time, the current limit value of the inverter, the rate of change in the rotation speed of the electric motor 60, the cooling water temperature of the electric motor 60 and its inverter, and the like.

Further, the "compressor 64" in the present embodiment has a function of supplying air to the cathode electrode of the fuel cell stack 10 via the cathode gas supply passage 22. Therefore, if such a function can be fulfilled, the "compressor 64" may be appropriately used in addition to the "compressor" (compressor having an effective discharge pressure of 200 kPa or more) which is generally recognized. It can be replaced with other compressors such as blowers and blowers.

Further, the "turbine 62" in the present embodiment is connected to the fuel cell stack 10 via the cathode gas discharge passage 24. More specifically, the combustor 32 provided in the cathode gas discharge passage 24 burns the cathode exhaust gas from the fuel cell stack 10 together with hydrogen, and supplies the generated combustion gas to the turbine 62. However, the present invention is not limited to this, and for example, the turbine 62 may be configured in a system separate from the cathode gas discharge passage 24. For example, a supply system for supplying gas from an arbitrary gas supply source to the turbine 62 and a mechanism for adjusting the supply flow rate and temperature of the gas to the turbine 62 may be separately provided.

10 Fuel cell stack 12 Cathode supply / exhaust mechanism 14 Cathode supply mechanism 16 Turbo compressor 17 Heating / cooling mechanism 18 HFR measuring device 19 Load device 20 Controller 22 Cathode gas supply passage 24 Cathode gas discharge passage 26 Air flow meter 28 Air pressure sensor 30 Stack outlet temperature sensor 32 Combustor 34 Nozzle vane 36 Bypass passage 38 Bypass valve 39 Turbine bypass passage 40 High pressure tank 42 Hydrogen heater 44 Hydrogen supply passage for stack 46 Hydrogen supply passage for combustor 47 Hydrogen pressure detection sensor 48 Stack supply hydrogen pressure regulating valve 49 Combustion Instrument Hydrogen amount control valve 51 Current sensor 52 Voltage sensor 60 Motor 62 Turbine 64 Compressor 100 Fuel cell system

Claims (7)

A fuel supply device that supplies fuel to the anode pole of a fuel cell,
An oxidant supply device that supplies an oxidant to the cathode electrode of the fuel cell,
An operating state detection unit that detects the operating state of the fuel cell,
A fuel cell system including an operation control device that controls the fuel supply device and the oxidant supply device by a signal from the operation state detection unit.
The oxidant supply device includes a compressor and an electric motor for driving the compressor.
The operation control device has a steady state determination unit that determines whether or not the system is in a steady operation state, and a motor output upper limit value that sets an output upper limit value of the electric motor based on a determination result by the steady state determination unit. Setting part and
A system request output calculation unit that calculates the system request output corresponding to the running power of the vehicle based on the accelerator pedal operation amount of the vehicle on which the fuel cell system is mounted,
It has a target power generation current setting unit that sets a target power generation current of the fuel cell based on the calculated system required output.
The motor output upper limit value setting unit is
Based on the target generated current, the maximum generated power required motor power corresponding to the electric power to be supplied from the fuel cell to the electric motor is calculated.
The maximum power generation required motor power is calculated so as to be lower in the high load region where the target power generation current is equal to or more than the predetermined value than in the low / medium load region where the target generated current is less than the predetermined value.
Fuel cell system. A fuel supply device that supplies fuel to the anode pole of a fuel cell,
An oxidant supply device that supplies an oxidant to the cathode electrode of the fuel cell,
An operating state detection unit that detects the operating state of the fuel cell,
A fuel cell system including an operation control device that controls the fuel supply device and the oxidant supply device by a signal from the operation state detection unit.
The oxidant supply device includes a compressor and an electric motor for driving the compressor.
The operation control device has a steady state determination unit that determines whether or not the system is in a steady operation state, and a motor output upper limit value that sets an output upper limit value of the electric motor based on a determination result by the steady state determination unit. Setting part and
A system request output calculation unit that calculates the system request output corresponding to the running power of the vehicle based on the accelerator pedal operation amount of the vehicle on which the fuel cell system is mounted,
It has a target power generation current setting unit that sets a target power generation current of the fuel cell based on the calculated system required output.
The motor output upper limit value setting unit is
The output limit value of the fuel cell is calculated based on the operating state of the fuel cell detected by the operating state detection unit.
Comparing the calculated output limit value of the fuel cell with the system required output,
The larger the system required output with respect to the output limit value of the fuel cell, the lower the output upper limit value of the electric motor is set.
Fuel cell system. In the fuel cell system according to claim 1 or 2 .
A turbine that drives the compressor independently of the electric motor, and a combustor that burns the fuel and the oxidizing agent to generate combustion gas for driving the turbine are further provided.
The operation control device is
An output distribution adjusting unit that adjusts the output of the electric motor and the output distribution of the recovered power of the turbine according to the required load on the fuel cell.
A fuel supply control unit that controls the fuel supply amount to the combustor based on the recovery power of the turbine determined by the output distribution adjustment unit is further provided.
Fuel cell system. In the fuel cell system according to claim 3 .
The output distribution adjusting unit adjusts the recovery power of the turbine so that the difference between the output of the electric motor and the output upper limit value of the electric motor is equal to or less than a predetermined value.
Fuel cell system. In the fuel cell system according to claim 4 .
The output distribution adjusting unit calculates the target compressor power based on the required load on the fuel cell, and calculates the target turbine recovery power by subtracting the output upper limit value of the electric motor from the target compressor power.
The fuel supply control unit calculates a target fuel supply amount, which is a target value of the fuel supply amount to the combustor, based on the target turbine recovery power, and the combustor is based on the calculated target fuel supply amount. Control the amount of fuel supplied to
Fuel cell system. The fuel cell system according to any one of claims 1 to 5 .
The steady operation state is
The motor output excess amount, which is the value obtained by subtracting the output upper limit value of the electric motor from the output of the electric motor, is in a state of being equal to or less than a predetermined value.
Fuel cell system. The fuel cell system according to any one of claims 1 to 6 .
The motor output upper limit value setting unit is
The smallest of the continuous rated power of the electric motor, the maximum load required motor power set based on the required load on the fuel cell, and the output limit value of the fuel cell is set as the output upper limit value of the electric motor. Set,
Fuel cell system.

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