JP6995635B2 - Fuel cell system - Google Patents

Description

The present invention relates to a fuel cell system.

The fuel cell system comprises a fuel cell stack that generates power by a chemical reaction between the fuel gas and the oxidant gas. The output power (= power generation amount) of the fuel cell stack increases as the amount of fuel gas supplied to the fuel cell stack and the amount of oxidant gas supplied to the fuel cell stack increase. The fuel cell system includes a control unit that calculates an output command value that is a target value of the output power of the fuel cell stack and controls the output power of the fuel cell stack to follow the output command value. The control unit controls the output power of the fuel cell stack by adjusting the supply amount of the fuel gas and the supply amount of the oxidant gas according to the output command value.

Patent Document 1 describes that the output performance of the fuel cell stack may decrease. When the output performance of the fuel cell stack deteriorates, the output power (actual output power) does not follow the output command value even if the fuel gas and the oxidant gas of the supply amount corresponding to the output command value are supplied. That is, only output power lower than the output command value can be obtained.

Japanese Unexamined Patent Publication No. 2007-280645

As described above, the supply amount of the fuel gas and the supply amount of the oxidant gas are determined according to the output command value. Therefore, when the output power is lower than the output command value, the fuel cell stack is excessive in an attempt to output the output power according to the output command value even though the output power according to the output command value is not output. It means that air is being supplied. Excessive air supply to the fuel cell stack reduces the humidity in the fuel cell stack. As a result, the deterioration of the fuel cell stack will be accelerated.

An object of the present invention is to provide a fuel cell system capable of suppressing deterioration of a fuel cell stack.

The fuel cell system that solves the above problems adjusts the fuel cell stack, the first adjusting unit that adjusts the supply amount of the fuel gas to the fuel cell stack, and the supply amount of the oxidizing agent gas to the fuel cell stack. A second adjusting unit, a detecting unit that detects the output power of the fuel cell stack, and a control unit that controls the first adjusting unit and the second adjusting unit are provided, and the control unit is the fuel cell stack. An output command value that is a target value of the output power of the fuel cell stack is obtained, and feedback control is performed so that the output power of the fuel cell stack follows the output command value based on the detection result of the detection unit. When a specific condition including an output deviation condition in which the output deviation of is equal to or more than a threshold value and a continuation condition in which the output deviation condition is continuously satisfied for a predetermined time or longer is satisfied, when the specific condition is satisfied. The adjusted output command value whose target value is lower than the output command value of the above is defined as the output command value.

According to this, when the output deviation condition and the specific condition including the continuation condition are satisfied, the adjusted output command value becomes the output command value. Since the control unit performs feedback control to reduce the output deviation, the output deviation condition and the continuation condition are satisfied when the output deviation, which is the difference between the output command value and the output power, does not decrease. It can be said that the situation is maintained. In other words, it can be said that the output power does not increase even though the supply amount of the fuel gas and the supply amount of the oxidant gas are increased in an attempt to make the output power follow the output command value. The adjusted output command value is a value lower than the target value at the time when the specific condition is satisfied. By setting the adjusted output command value as the output command value, the amount of fuel gas supplied to the fuel cell stack and the amount of oxidant gas supplied will be smaller than when the specific conditions are satisfied. When the output performance is deteriorated due to deterioration of the fuel cell stack or the usage environment, the output command value becomes low, so that the supply amount of the oxidant gas can be suppressed. Therefore, it is possible to suppress the supply of excess oxidant gas to the fuel cell stack and suppress the deterioration of the fuel cell stack.

The specific condition may include an integral term condition in which the feedback integral term of the output command value is an upper limit value.
The situation where the feedback integral term becomes the upper limit is the situation where the output deviation does not decrease even though the feedback integral term is increased in order to reduce the output deviation. By including the integral term condition in the specific condition, it is possible to more appropriately determine whether or not the adjusted output command value is used as the output command value.

The fuel cell system includes a power storage device connected in parallel to a load to which the fuel cell stack is connected, and a charge rate detection unit for detecting the charge rate of the power storage device, and the control unit has the charge rate. The output command value is switched stepwise according to the charge rate of the power storage device detected by the detection unit, and when the specific condition is satisfied, one step of the output command value at the time when the specific condition is satisfied. The output command value below may be used as the adjusted output command value.

Since the output command value is switched step by step, when obtaining the adjusted output command value, the output command value one step lower than the output command value at the time when a specific condition is satisfied is set as the adjusted output command value. do it. Therefore, it becomes easy to calculate the adjusted output command value.

The fuel cell system that solves the above problems adjusts the fuel cell stack, the first adjusting unit that adjusts the supply amount of the fuel gas to the fuel cell stack, and the supply amount of the oxidizing agent gas to the fuel cell stack. A second adjusting unit, a detecting unit that detects the output power of the fuel cell stack, and a control unit that controls the first adjusting unit and the second adjusting unit are provided, and the control unit is the fuel cell stack. An output command value that is a target value of the output power of the fuel cell stack is obtained, and feedback control is performed so that the output power of the fuel cell stack follows the output command value based on the detection result of the detection unit. When a specific condition including an integration term condition in which the feedback integration term of the fuel cell stack is an upper limit value and an output deviation condition in which the output deviation of the fuel cell stack is equal to or more than a threshold value is satisfied, the said at the time when the specific condition is satisfied. The adjusted output command value whose target value is lower than the output command value is defined as the output command value.

According to this, when the integral term condition and the specific condition including the output deviation condition are satisfied, the adjusted output command value becomes the output command value. In the situation where the integration term condition and the output deviation condition are satisfied, the output deviation, which is the difference between the output command value and the output power, is equal to or more than the threshold value, and the feedback integration term is increased in order to reduce the output deviation. Nevertheless, the output deviation does not decrease. In other words, it can be said that the output power does not increase even though the supply amount of the fuel gas and the supply amount of the oxidant gas are increased in an attempt to make the output power follow the output command value. The adjusted output command value is a value lower than the target value at the time when the specific condition is satisfied. By setting the adjusted output command value as the output command value, the amount of fuel gas supplied to the fuel cell stack and the amount of oxidant gas supplied will be smaller than when the specific conditions are satisfied. When the output performance is deteriorated due to deterioration of the fuel cell stack or the usage environment, the output command value becomes low, so that the supply amount of the oxidant gas can be suppressed. Therefore, it is possible to suppress the supply of excess oxidant gas to the fuel cell stack and suppress the deterioration of the fuel cell stack.

According to the present invention, deterioration of the fuel cell stack can be suppressed.

Block diagram showing a fuel cell system. The control block diagram which shows the control mode which makes the output power follow an output command value. The figure which shows the process of deriving the output command value. A state transition diagram showing a switching mode of output states.

Hereinafter, an embodiment of the fuel cell system will be described. The fuel cell system of the present embodiment is mounted on a vehicle such as a passenger car or an industrial vehicle (for example, a forklift).

As shown in FIG. 1, the fuel cell system 10 includes a fuel cell stack 11. The fuel cell stack 11 is a stack of a plurality of fuel cell cells. The fuel cell is, for example, a polymer electrolyte fuel cell. The fuel cell stack 11 generates electricity by a chemical reaction between the fuel gas and the oxidant gas. In this embodiment, hydrogen gas is used as a fuel gas and oxygen in the air is used as an oxidant gas to generate power. The fuel cell system 10 is a system in which the load 30 is driven by the electric power generated by the fuel cell stack 11.

The fuel cell system 10 sucks the hydrogen tank 12 in which the hydrogen gas is stored, the electromagnetic valve 13 for adjusting the supply amount of the hydrogen gas from the hydrogen tank 12 to the fuel cell stack 11, and the air in the atmosphere. A compressor 14 that discharges compressed air is provided. Further, the fuel cell system 10 adjusts the supply amount of hydrogen gas to the fuel cell stack 11 and the supply amount of air to the fuel cell stack 11 to reduce the output power Pg (power generation amount) of the fuel cell stack 11. An ECU (electronic control unit) 15 as a control unit for control is provided.

The hydrogen tank 12 has a cylindrical cross section and stores high-pressure hydrogen gas. The solenoid valve 13 is an electromagnetically driven on-off valve in which the valve body is electromagnetically driven according to the drive cycle and valve opening time set by the ECU 15. By controlling the drive cycle and valve opening time of the solenoid valve 13, the amount of hydrogen gas supplied to the fuel cell stack 11 is controlled by the ECU 15.

The compressor 14 is an electric compressor driven by an electric motor. By controlling the torque of the electric motor by the ECU 15, the amount of air supplied to the fuel cell stack 11 is controlled. Specifically, the compressor 14 includes an inverter INV connected to an electric motor, and the inverter INV is controlled by the ECU 15, so that the amount of air supplied to the fuel cell stack 11 is controlled. The solenoid valve 13 functions as a first adjusting unit, and the compressor 14 functions as a second adjusting unit.

The fuel cell system 10 has a DC / DC converter 16 provided between the fuel cell stack 11 and the load 30, a power storage device 17 connected in parallel to the load 30, and a charge rate for detecting the charge rate of the power storage device 17. A voltage estimation unit 23 as a detection unit is provided. The DC / DC converter 16 transforms and outputs the output voltage of the fuel cell stack 11. When the output power Pg of the fuel cell stack 11 exceeds the required power Pw of the load 30, the surplus power is charged to the power storage device 17. When the output power Pg of the fuel cell stack 11 is less than the required power Pw of the load 30, the insufficient power is discharged from the power storage device 17.

The power storage device 17 is capable of discharging and charging, and for example, a secondary battery or a capacitor is used. The voltage estimation unit 23 obtains the charge amount of the power storage device 17 by integrating the currents input and output to the power storage device 17, and estimates the closed circuit voltage of the power storage device 17 based on the charge amount. The closed circuit voltage estimated by the voltage estimation unit 23 is output to the ECU 15. The ECU 15 calculates the charge rate of the power storage device 17 based on the closed circuit voltage.

The fuel cell stack 11 includes a voltage sensor 21. The voltage sensor 21 detects the output voltage of the fuel cell stack 11. The voltage sensor 21 outputs the detection result to the ECU 15. The DC / DC converter 16 includes a current sensor 22. The current sensor 22 detects the input current to the DC / DC converter 16. The current input to the DC / DC converter 16 is output from the fuel cell stack 11, and the input current to the DC / DC converter 16 can be said to be the output current of the fuel cell stack 11. The current sensor 22 outputs the detection result to the ECU 15. The ECU 15 can calculate the output power Pg of the fuel cell stack 11, in other words, the amount of power generated by the fuel cell stack 11 from the output voltage and output current of the fuel cell stack 11. In the present embodiment, the output power Pg is calculated from the detection results of the voltage sensor 21 and the current sensor 22, so that the voltage sensor 21 and the current sensor 22 detect the output power Pg of the fuel cell stack 11. It can be said that it functions as.

The output power Pg of the fuel cell stack 11 varies depending on the amount of hydrogen gas supplied to the fuel cell stack 11 and the amount of air supplied to the fuel cell stack 11.
The ECU 15 controls the output power Pg of the fuel cell stack 11 by adjusting the supply amount of hydrogen gas to the fuel cell stack 11 and the supply amount of air. The ECU 15 calculates an output command value Pc which is a target value of the output power Pg of the fuel cell stack 11. Then, the ECU 15 controls the solenoid valve 13 and the compressor 14 so that the output power Pg of the fuel cell stack 11 follows the output command value Pc. Hereinafter, a detailed description will be given.

As shown in FIG. 2, the ECU 15 controls the output power Pg of the fuel cell stack 11 by using the feedforward control and the feedback control (PI control) in combination.
When the output command value Pc [kW] is obtained by calculation, the ECU 15 calculates the current command value (FF) [A] from the output command value Pc. The current command value (FF) is calculated from the current-voltage characteristic of the fuel cell stack 11 and the ford forward gain.

Further, the ECU 15 calculates the output power Pg [kW] from the output voltage and the output current. In FIG. 2, the output voltage is referred to as FC voltage, the output current is referred to as FC current, and the output power Pg is referred to as FC actual power. The ECU 15 calculates an output deviation ΔP [kW] from the output command value Pc and the output power Pg. The ECU 15 calculates the current command value (FB) [A] from the output deviation ΔP, the proportional gain, and the integrated gain. More specifically, the ECU 15 calculates the feedback proportional term from the output deviation ΔP and the proportional gain, and calculates the feedback integral term from the integrated value and the integrated gain of the output deviation ΔP. The sum of the feedback proportional term and the feedback integral term is the current command value (FB).

The ECU 15 uses the sum of the current command value (FF) and the current command value (FB) as the current command value. The ECU 15 controls the solenoid valve 13 and the compressor 14 so that the amounts of hydrogen gas and air corresponding to the current command value are supplied to the fuel cell stack 11. As a result, the supply amount of hydrogen gas and the supply amount of air are adjusted so that the output power Pg follows the output command value Pc.

However, due to deterioration of the fuel cell stack 11, the usage environment, and the like, the output power Pg of the fuel cell stack 11 may not be sufficiently obtained. In this case, the output deviation ΔP may not be small. That is, the output power Pg of the fuel cell stack 11 may be lower than the output command value Pc, and air may be excessively supplied.

The ECU 15 calculates the output command value Pc by the following control to suppress the supply of an excessive amount of air to the fuel cell stack 11.
As shown in FIG. 3, the ECU 15 of the present embodiment calculates an output command value Pc by performing a two-step process of a power generation amount determination process and a power generation amount deviation adjustment process. The power generation amount determination process is a process of determining the output command value Pc1 (target value of the power generation amount) of the fuel cell stack 11 according to the charge rate of the power storage device 17. In the power generation amount deviation adjustment process, when a specific condition is satisfied, the value of the output command value Pc1 calculated in the power generation amount determination process is adjusted, and the adjusted output command value Pc2, which is the adjusted output command value, is newly added. This is a process for setting the output command value Pc.

First, the power generation amount determination process will be described.
As shown in FIG. 4, the ECU 15 steps to switch the output state of the fuel cell stack 11 according to the charge rate of the power storage device 17. The output state of this embodiment is a four-stage state of power generation stop state S1, low output state S2, medium output state S3, and high output state S4. The output command value Pc1 differs depending on the four output states. Therefore, the output command value Pc1 is gradually switched along with the output state.

The power generation stop state S1 is a state in which the fuel cell stack 11 does not generate power. In the power generation stop state S1, the output command value Pc1 = 0 [kW].
The low output state S2 is a state in which power is generated at the lowest value that can be generated without deterioration of the fuel cell stack 11. The output command value Pc1 in the low output state S2 is a value larger than that in the power generation stop state S1, and for example, the output command value Pc1 = 3 [kW].

The medium output state S3 is a state in which the amount of power generated by the fuel cell stack 11 is larger than that in the low output state S2. The output command value Pc1 in the medium output state S3 is a value larger than that in the low output state S2, and for example, the output command value Pc1 = 6 [kW]. The output command value Pc1 in the medium output state S3 is set to an average value of the required power Pw of the load 30 when the vehicle operates under normal usage conditions.

The high output state S4 is a state in which the required power Pw of the load 30 when the vehicle operates at the maximum load is output to the fuel cell stack 11. The output command value Pc1 in the high output state S4 is a value larger than that in the medium output state S3, and for example, the output command value Pc1 = 12 [kW]. The medium output state S3 can be said to be a state between the low output state S2 and the high output state S4.

The ECU 15 appropriately switches the output state of the fuel cell stack 11 according to the charge rate of the power storage device 17. First, when the fuel cell stack 11 is in the power generation stop state S1 and the charge rate of the power storage device 17 becomes the power generation start threshold V _D = 50 [%] or less, the fuel cell stack 11 starts power generation. The output state shifts from the power generation stop state S1 to the low output state S2.

When the charge rate of the power storage device 17 is equal to or less than the medium output switching threshold _VM = 45 [%] when the fuel cell stack 11 is in the low output state S2, the output state of the fuel cell stack 11 is in the low output state S2. Shifts to the medium output state S3.

When the charge rate of the power storage device 17 becomes the high output switching threshold V _H = 30 [%] or less when the fuel cell stack 11 is in the medium output state S3, the output state of the fuel cell stack 11 is the medium output state S3. Shifts to the high output state S4. The high output switching threshold value _VH is set as the minimum charge rate of the power storage device 17 in order to protect the fuel cell system 10 when the vehicle is used under the strictest conditions.

On the other hand, when the fuel cell stack 11 is in the high output state S4 and the charge rate of the power storage device 17 becomes the medium output switching threshold _VM = 45 [%] or more, the output state of the fuel cell stack 11 is high output. The state S4 shifts to the medium output state S3.

When the charge rate of the power storage device 17 becomes the output switching threshold value _VL = 60 [%] or more when the fuel cell stack 11 is in the medium output state S3, the output state of the fuel cell stack 11 is from the medium output state S3. It shifts to the low output state S2.

When the charge rate of the power storage device 17 becomes the power generation stop threshold _VS = 70 [%] or more when the fuel cell stack 11 is in the low output state S2, the fuel cell stack 11 stops power generation and is in the output state. Shifts from the low output state S2 to the power generation stop state S1. The power generation stop threshold _VS is set as the maximum charge rate for preventing the power storage device 17 from becoming overcharged, and the power storage device 17 regenerates 30 [%] of the remaining charge rate. It is secured as a surplus necessary to receive energy. In the fuel cell system 10, the medium output switching threshold _{VM = 45 [%] is set to an intermediate value between the high output switching threshold V H =} 30 [%] and the output switching threshold _VL = 60 [%]. There is. As described above, the output command value Pc1 changes according to the charge rate of the power storage device 17.

Next, the power generation amount deviation adjustment process will be described.
In the present embodiment, the adjusted output command value Pc2 is the output command value Pc1 in the output state one step lower than the output command value Pc1 at the time when the specific condition is satisfied. If the output state is the high output state S4 when the specific condition is satisfied, the adjusted output command value Pc2 becomes the output command value Pc1 in the medium output state S3. If the output state is the medium output state S3 when the specific condition is satisfied, the adjusted output command value Pc2 becomes the output command value Pc1 in the low output state S2. When the output state is the low output state S2 when the specific condition is satisfied, the output command value Pc1 is maintained at the output command value Pc1 in the low output state S2.

When the following integration term condition, output deviation condition, and continuation condition are satisfied as specific conditions, the ECU 15 sets the adjusted output command value Pc2 as the output command value Pc. That is, if the integration term condition, the output deviation condition, and the continuation condition are not satisfied, the output power Pg of the fuel cell stack 11 is controlled so as to follow the output command value Pc1 calculated in the power generation amount determination process. On the other hand, if the integration term condition, the output deviation condition, and the continuation condition are satisfied, the output power Pg of the fuel cell stack 11 is controlled so as to follow the adjusted output command value Pc2.

Integral term condition: The feedback integral term of the output command value Pc is the upper limit.
Output deviation condition: The output deviation ΔP of the fuel cell stack 11 is equal to or greater than the threshold value.
Continuation condition: Both the integration term condition and the output deviation condition are continuously satisfied for a predetermined time or longer.

The Fordback integral term under the integral term condition becomes larger as the output deviation ΔP becomes larger. The upper limit value of the feedback integration term is an upper limit value set by the fuel cell system 10. This upper limit value is set so that the value of the current command value does not rise excessively in consideration of the characteristics of the fuel cell stack 11 and the like.

The threshold value of the output deviation ΔP under the output deviation condition is a value determined based on the simulation result, the experimental result, and the like. Since the feedback control is performed in order to reduce the output deviation ΔP, the output deviation ΔP is within a predetermined range if there is no problem in the output performance of the fuel cell stack 11. The threshold value of the output deviation ΔP is set to a value larger than this predetermined range.

Here, in the situation where the integration term condition and the output deviation condition are satisfied, the output deviation ΔP, which is the difference between the output command value Pc and the output power Pg, is equal to or more than the threshold value, and the feedback integration term is used to reduce the output deviation ΔP. However, the output deviation ΔP does not decrease. In other words, it can be said that the output power Pg does not increase even though the supply amount of hydrogen gas and the supply amount of air are increased in an attempt to make the output power Pg follow the output command value Pc. In such a situation, the output performance is permanently or temporarily deteriorated depending on the deterioration of the fuel cell stack 11 and the usage environment.

The predetermined time in the continuation condition is to prevent the output command value Pc from becoming the adjusted output command value Pc2 when the integral term condition and the output deviation condition are accidentally satisfied due to a disturbance or the like. It is a set time. The predetermined time is set based on the simulation result, the experimental result, and the like. It can be said that the continuation condition determines whether both conditions are continuously satisfied in the determination of the establishment of the integral term condition and the output deviation condition repeated in a predetermined control cycle.

Next, the operation of the fuel cell system 10 of the present embodiment will be described.
When the output performance of the fuel cell system 10 deteriorates, the output power Pg may be insufficient with respect to the supply amounts of air and hydrogen gas. In this case, as the output deviation ΔP increases, the feedback integral term of the output command value Pc increases in each control cycle.

When the specific condition is satisfied, the ECU 15 sets the adjusted output command value Pc2 as the output command value Pc. The adjusted output command value Pc2 is a value lower than the output command value Pc at the time when the specific condition is satisfied. By setting the adjusted output command value Pc2 as the output command value Pc, the amount of hydrogen gas supplied to the fuel cell stack 11 and the amount of air supplied will be smaller than when the specific conditions are satisfied.

As the output command value Pc becomes lower, the output deviation ΔP also becomes smaller. As a result, when either the integral term condition or the output deviation condition is not satisfied, it can be said that the fuel cell stack 11 is supplied with the supply amount of air and hydrogen gas corresponding to the output performance.

On the other hand, if the specific condition is satisfied even though the adjusted output command value Pc2 is set to the output command value Pc, the output command value Pc is further lowered. For example, when the specific condition is satisfied in the high output state S4 and the specific condition is still satisfied even though the output command value Pc1 in the medium output state S3 is set to the output command value Pc, the low output state S2 The output command value Pc1 of is set as the output command value Pc.

Therefore, according to the above embodiment, the following effects can be obtained.
(1) When the specific condition is satisfied, the adjusted output command value Pc2 of the target value lower than the output command value Pc at the time when the specific condition is satisfied is set as the output command value Pc. When the output performance is deteriorated due to deterioration of the fuel cell stack 11 or the usage environment, the output command value Pc is lowered, so that the air supply amount can be suppressed. Therefore, it is possible to suppress the supply of excess air to the fuel cell stack 11 and suppress the deterioration of the fuel cell stack 11. As a result, it is possible to suppress the acceleration of deterioration of the fuel cell stack 11.

(2) The specific condition includes an integral term condition in addition to the output deviation condition and the continuation condition. The situation in which the feedback integral term becomes the upper limit value is a situation in which the output deviation ΔP does not decrease even though the feedback integral term is increased in order to decrease the output deviation ΔP. By including the integral term condition in the specific condition, it is possible to more appropriately determine whether or not the adjusted output command value is used as the output command value.

(3) The ECU 15 gradually switches the output state. The output command value Pc1 is different for each output state, and it can be said that the ECU 15 gradually switches the output command value Pc. When the integration term condition and the output deviation condition are satisfied, the output command value Pc1 one step lower than the output command value Pc1 at the time when both conditions are satisfied becomes the adjusted output command value Pc2. Since the output command value Pc1 is associated with the output state and is predetermined, it is easy to calculate the adjusted output command value Pc2.

The embodiment may be changed as follows.
○ The specific conditions may be only the output deviation condition and the continuation condition. That is, when both the output deviation condition and the continuation condition are satisfied, the adjusted output command value Pc2 may be set to the output command value Pc. The continuation condition in this case is that the output deviation condition is continuously satisfied for a predetermined time or longer.

The situation in which the output deviation condition and the continuation condition are satisfied is a situation in which the state in which the output deviation ΔP is equal to or greater than the threshold value is continued for a predetermined time or longer. As described above, since the feedback control is performed to reduce the output deviation ΔP, the output deviation ΔP is reduced when the state in which the output deviation ΔP is equal to or higher than the threshold value continues for a predetermined time or longer. It can be said that the output deviation ΔP does not fall below the threshold value despite the attempt. In other words, it can be said that the output power Pg does not increase even though the supply amount of hydrogen gas and the supply amount of air are increased in an attempt to make the output power Pg follow the output command value Pc. In such a situation, the output performance is permanently or temporarily deteriorated depending on the deterioration of the fuel cell stack 11 and the usage environment.

The "predetermined time" in the continuation condition in this case is the time during which it can be determined whether or not the output performance of the fuel cell stack 11 has deteriorated from the time during which the output deviation ΔP is maintained above the threshold value. Is set to. Specifically, it is longer than this time, assuming the time required to transition the output deviation ΔP from the state above the threshold value to the state below the threshold value in a state where the output performance of the fuel cell stack 11 is not deteriorated. Set to time. When the output performance of the fuel cell stack 11 deteriorates and the output deviation ΔP cannot be made less than the threshold value, a specific condition is satisfied. As a result, it is possible to suppress the supply of excess air to the fuel cell stack 11 and suppress the deterioration of the fuel cell stack 11.

○ The adjusted output command value Pc2 may be a value lower than the target value Pc when the specific condition is satisfied, and a predetermined value is subtracted from the output command value Pc when the specific condition is satisfied. It may be a value that has been set. The predetermined value may be a fixed value or a variable value. When a predetermined value is set as a fixed value, the value is set based on the experimental result or the simulation result. When the predetermined value is a variable value, the value of the predetermined value may be changed according to the output command value Pc and the output deviation ΔP. For example, the larger the output command value Pc, the larger the predetermined value, or the larger the output deviation ΔP, the larger the predetermined value. When the value obtained by subtracting the predetermined value from the output command value Pc at the time when the specific condition is satisfied becomes 0 or less, the ECU 15 may maintain the output command value Pc without subtracting the predetermined value. ..

Further, the adjusted output command value Pc2 is a value less than 100% of the output command value Pc at the time when the specific condition is satisfied, such as a value of 50% to 95% of the output command value Pc at the time when the specific condition is satisfied. May be.

○ The output command value Pc1 calculated in the power generation amount determination process may be linearly switched according to the charge rate of the power storage device 17. As the adjusted output command value Pc2 in this case, as described above, a predetermined value is subtracted from the output command value Pc when the specific condition is satisfied, or the output command value Pc when the specific condition is satisfied. It is calculated from the ratio.

○ The output command value Pc may be calculated from factors other than the charge rate of the power storage device 17. For example, the output command value Pc may be calculated from the required power Pw of the load 30. If the fuel cell system 10 is mounted on the vehicle as in the embodiment, for example, the required power Pw of the load 30 can be calculated from the operation amount of the accelerator pedal.

○ The output state (output command value Pc1) may be in three or more stages or in five or more stages.
○ The continuation condition may be that the output deviation condition is continuously satisfied for a predetermined time or longer. The time during which the integral term condition is continuously satisfied does not have to be included in the specific condition.

○ The specific conditions may be only the integral term condition and the output deviation condition. That is, when both the integration term condition and the output deviation condition are satisfied, the adjusted output command value Pc2 may be set to the output command value Pc.

In this case, even if the integral term condition and the output deviation condition are accidentally satisfied due to factors such as disturbance, the adjusted output command value Pc2 becomes the output command value Pc, and the output power of the fuel cell stack 11 Pg will decrease. However, when the integration term condition and the output deviation condition are accidentally satisfied, the period during which the integration term condition and the output deviation condition are satisfied is temporary, and the output power Pg of the fuel cell stack 11 decreases. However, it is considered that there will be no practical hindrance.

Further, the lower the output command value Pc, the smaller the amount of air supplied. Therefore, even if the output command value Pc is erroneously lowered due to disturbance or the like, the deterioration of the fuel cell stack 11 is not promoted due to the excessive supply of air.

○ The feedback control performed by the ECU 15 may include at least an integral operation (I operation), and may be PID control.
○ The ECU 15 may calculate the current command value only by feedback control. That is, it is not necessary to perform feedforward control.

○ An ECU that calculates the output command value Pc and an ECU that controls the output power Pg of the fuel cell stack 11 according to the output command value Pc may be separately provided. In this case, a plurality of ECUs will function as control units.

○ The fuel cell stack 11 may be mounted on a mobile device or used as a stationary power source.

10 ... Fuel cell system, 11 ... Fuel cell stack, 13 ... Electromagnetic valve (1st adjustment unit), 14 ... Compressor (2nd adjustment unit), 15 ... ECU (control unit), 17 ... Power storage device, 21 ... Voltage sensor (Detection unit), 22 ... Current sensor (detection unit), 23 ... Voltage estimation unit (charge rate detection unit).

Claims (4)

With the fuel cell stack,
A first adjusting unit that adjusts the amount of fuel gas supplied to the fuel cell stack, and
A second adjusting unit that adjusts the amount of oxidant gas supplied to the fuel cell stack, and
A detector that detects the output power of the fuel cell stack,
A control unit that controls the first adjustment unit and the second adjustment unit is provided.
The control unit
An output command value that is a target value of the output power of the fuel cell stack is obtained, and based on the detection result of the detection unit, the oxidant gas is used so that the output power of the fuel cell stack follows the output command value. Feedback control is performed to adjust the supply amount ,
The output deviation condition in which the output deviation of the fuel cell stack is equal to or greater than the threshold value, and
When a specific condition including a continuation condition in which the output deviation condition is continuously satisfied for a predetermined time or longer is satisfied, an adjustment having a target value lower than the output command value at the time when the specific condition is satisfied is satisfied. The post-output command value is set as the output command value.
A fuel cell system that performs feedback control so that the output power of the fuel cell stack follows the adjusted output command value so that the supply amount of the oxidant gas is suppressed from the time when the specific condition is satisfied . The fuel cell system according to claim 1, wherein the specific condition includes an integral term condition in which the feedback integral term of the output command value is an upper limit value. A power storage device connected in parallel to the load to which the fuel cell stack is connected, and
A charge rate detection unit for detecting the charge rate of the power storage device is provided.
The control unit
The output command value is switched stepwise according to the charge rate of the power storage device detected by the charge rate detector.
The fuel according to claim 1 or 2, wherein when the specific condition is satisfied, the output command value one step below the output command value at the time when the specific condition is satisfied is set as the adjusted output command value. Battery system. With the fuel cell stack,
A first adjusting unit that adjusts the amount of fuel gas supplied to the fuel cell stack, and
A second adjusting unit that adjusts the amount of oxidant gas supplied to the fuel cell stack, and
A detector that detects the output power of the fuel cell stack,
A control unit that controls the first adjustment unit and the second adjustment unit is provided.
The control unit
An output command value that is a target value of the output power of the fuel cell stack is obtained, and based on the detection result of the detection unit, the oxidant gas is used so that the output power of the fuel cell stack follows the output command value. Feedback control is performed to adjust the supply amount ,
An integral term condition in which the feedback integral term of the output command value is an upper limit value, and
When a specific condition including an output deviation condition in which the output deviation of the fuel cell stack is equal to or greater than a threshold value is satisfied, an adjusted output command having a target value lower than the output command value at the time when the specific condition is satisfied is satisfied. The value is set as the output command value.
A fuel cell system that performs feedback control so that the output power of the fuel cell stack follows the adjusted output command value so that the supply amount of the oxidant gas is suppressed from the time when the specific condition is satisfied .

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