JP7208118B2 - Fuel cell system control method - Google Patents

Description

The present invention relates to a fuel cell system control method.

Generally, a fuel cell stack having a plurality of fuel cells generates electricity through an electrochemical reaction between hydrogen and oxygen. Therefore, a fuel cell system including a fuel cell stack includes a hydrogen supply unit that supplies hydrogen as a fuel gas to the fuel cell stack, and an air supply unit that supplies oxygen in the air as an oxidant gas to the fuel cell stack. is provided.

When hydrogen and air are supplied to the fuel cell stack to generate power, frequent fluctuations in the output power of the fuel cell stack tend to accelerate the deterioration of the fuel cells. Therefore, Patent Literature 1 describes a technique for switching the output state of the fuel cell unit in multiple stages according to the charging rate of the power storage device.

JP 2017-33834 A

When the fuel cell stack is to generate electricity, the amount of hydrogen supplied and the amount of air supplied are adjusted according to the command output required for the fuel cell stack. However, even if hydrogen and air are supplied in amounts corresponding to the commanded output, the actual output of the fuel cell stack may continue to fall below the commanded output. In that case, the amount of air supplied becomes excessive with respect to the actual output of the fuel cell stack, and there is a risk that the deterioration of the fuel cells will be hastened. Conventionally, there are several causes for the decrease in fuel cell stack output. , could not determine the cause of the output drop.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and an object of the present invention is to provide a method of controlling a fuel cell system that can narrow down the cause of the decrease in the output of the fuel cell stack more than the conventional method.

The present invention relates to a control method for a fuel cell system having a fuel cell stack having a plurality of fuel cells, in which an appropriate amount of air is supplied to the fuel cell stack when an abnormal output drop occurs in the fuel cell stack. a step of checking whether the air supply pressure to the fuel cell stack is appropriate; and a step of checking whether the dryness of the fuel cell is appropriate. In the process, when the amount of air supplied, the supply pressure of air, and the dryness of the fuel cells are all appropriate, a gas that inhibits the catalytic reaction of the fuel cells was sent into the fuel cell stack along with the air. This is presumed to be the cause of the abnormal output drop of the fuel cell stack.

In the fuel cell system control method according to the present invention, the deviation between the command output and the actual output of the fuel cell stack is equal to or greater than a threshold, and the integral term is used when the output of the fuel cell stack is feedback-controlled based on the deviation. is saturated, it is determined that an abnormal output drop has occurred in the fuel cell stack.

In the fuel cell system control method according to the present invention, when the average cell voltage of a plurality of fuel cells is below a predetermined allowable voltage and the voltage difference between each fuel cell is less than a predetermined value First, it is determined whether or not an abnormal decrease in output has occurred in the fuel cell stack.

In the fuel cell system control method according to the present invention, the dryness of the fuel cells is checked based on the impedance of the fuel cell stack.

In the fuel cell system control method according to the present invention, the dryness of the fuel cells is checked based on the temperature of the fuel cells.

According to the present invention, it is possible to narrow down the cause of the decrease in the output of the fuel cell stack more than in the conventional art.

1 is a schematic diagram showing the configuration of a fuel cell system according to an embodiment of the invention; FIG. FIG. 4 is a schematic diagram showing a connection state of a cell monitor; FIG. 4 is a diagram explaining a method of controlling the output of a fuel cell stack; 4 is a flow chart showing a method of controlling a fuel cell system according to an embodiment of the present invention;

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a schematic diagram showing the configuration of a fuel cell system according to an embodiment of the invention.
As shown in FIG. 1 , the fuel cell system 11 has a fuel cell stack 15 . The fuel cell stack 15 has a plurality of fuel cells 16 and has a stack structure in which these fuel cells 16 are stacked. Although not shown, each fuel cell 16 has a structure in which both sides of an electrolyte membrane are sandwiched between two separators. A cathode electrode is arranged on one side of the electrolyte membrane, and an anode electrode is arranged on the other side of the electrolyte membrane. A catalyst layer is formed on each electrode surface of the cathode electrode and the anode electrode, and the fuel cell 16 generates power through a chemical reaction (hereinafter also referred to as “catalytic reaction”) on the catalyst. Further, the fuel cell stack 15 includes a first end plate 21, a first insulating plate 22, a first collector plate 23, a plurality of fuel cells 16, a second collector plate 24, and a second insulating plate. 25 and the second end plate 26 are laminated in this order to form a stack structure.

A hydrogen supply unit 31 and an air supply unit 32 are connected to the fuel cell stack 15 . The hydrogen supply unit 31 is a unit for supplying hydrogen, which is fuel gas, to the fuel cell stack 15 . The hydrogen supply unit 31 has a hydrogen tank 34 , a tank valve 35 , a regulator 36 , an injector 37 , a hydrogen supply pipe 38 and a pressure sensor 39 . The pressure sensor 39 is a sensor that detects the hydrogen pressure in the fuel cell stack 15 . A detection result of the pressure sensor 39 is provided to the control section 12 . Hydrogen stored in the hydrogen tank 34 is supplied to the fuel cell stack 15 through the hydrogen supply pipe 38 . At that time, the hydrogen flowing through the hydrogen supply pipe 38 is supplied to the injector 37 via the tank valve 35 and the regulator 36 operated by the differential pressure, and the continuous opening and closing operation of the injector 37 causes the pressure sensor 39 to It is supplied to the fuel cell stack 15 .

The air supply unit 32 is a unit for supplying oxygen-containing air to the fuel cell stack 15 . The air supply unit 32 has a compressor 40 , an air supply pipe 41 , a flow rate sensor 47 and a pressure sensor 48 . Compressor 40 compresses the air sucked from the atmosphere. Air compressed by the compressor 40 is supplied to the fuel cell stack 15 through an air supply pipe 41 . The flow rate sensor 47 is a sensor that detects the amount of air supplied to the fuel cell stack 15 . The flow sensor 47 is electrically connected to the controller 12 . A detection result of the flow sensor 47 is provided to the control unit 12 . The pressure sensor 48 is a sensor that detects the pressure of air supplied to the fuel cell stack 15 . The pressure sensor 48 is electrically connected to the controller 12 . A detection result of the pressure sensor 48 is provided to the control section 12 .

A discharge pipe 43 , a cooling unit 44 , a discharge unit 45 , and a hydrogen circulation unit 46 are connected to the fuel cell stack 15 . The discharge pipe 43 is a pipe for discharging the cathode off-gas discharged from the fuel cell stack 15 into the atmosphere. The cooling unit 44 is a unit for cooling the fuel cell stack 15 . The cooling unit 44 has a temperature sensor 51 , a pipe 52 , a radiator 53 , a pump 54 and a pipe 55 . The cooling unit 44 recovers the heat of the fuel cell stack 15 by circulating cooling water as a cooling medium with the pump 54 , and releases the recovered heat to the atmosphere with the radiator 53 . The fuel cell stack 15 is thereby cooled. The temperature sensor 51 is a sensor that detects the temperature of cooling water flowing through the pipe 52 . A detection result of the temperature sensor 51 is given to the control unit 12 .

The discharge unit 45 is a unit for discharging anode off-gas discharged from the fuel cell stack 15 . The discharge unit 45 has an exhaust/drain valve 61 and a discharge pipe 62 . The exhaust/drain valve 61 is a valve for discharging the anode off-gas and the generated water contained therein through the discharge pipe 62 into the atmosphere.

The hydrogen circulation unit 46 is a unit for supplying the hydrogen contained in the anode off-gas discharged from the fuel cell stack 15 to the fuel cell stack 15 again through the hydrogen supply pipe 38 . The hydrogen circulation unit 46 has a hydrogen pump 65 for hydrogen circulation and a hydrogen circulation path 66 . Hydrogen contained in the anode off-gas discharged from the fuel cell stack 15 flows into the hydrogen supply pipe 38 through the hydrogen circulation path 66 by the hydrogen pump 65 and is supplied to the fuel cell stack 15 through the hydrogen supply pipe 38 .

The fuel cell system 11 includes the hydrogen supply unit 31, the air supply unit 32, the discharge pipe 43, the cooling unit 44, the discharge unit 45, and the hydrogen circulation unit 46 in addition to the fuel cell stack 15 described above.

A cell monitor 71 is electrically connected to the fuel cell stack 15 . The cell monitor 71 is individually connected to the plurality of fuel cells 16, as shown in FIG. Under this connection state, the cell monitor 71 detects the voltage of each fuel cell 16 (hereinafter also referred to as "cell voltage"). Also, the cell monitor 71 is electrically connected to the control unit 12 . A cell voltage detection result by the cell monitor 71 is provided to the control unit 12 .

Further, as shown in FIG. 1 , a DC/DC converter 75 is electrically connected to the fuel cell stack 15 . The DC/DC converter 75 steps down the DC power output from the fuel cell stack 15 to a predetermined voltage level and outputs it. The DC/DC converter 75 is electrically connected to the controller 12 . The storage battery 76 stores surplus power obtained by the fuel cell stack 15 or regenerated power generated by the load 78 . The storage battery 76 is composed of a secondary battery such as a rechargeable lithium ion battery. The inverter 77 converts the DC power output from the fuel cell stack 15 via the DC/DC converter 75 and the DC power output from the storage battery 76 into AC power and outputs the AC power to the load 78 . The load 78 operates electrically or mechanically upon receiving power supply. When the fuel cell system 11 is mounted on a fuel cell powered vehicle, the load 78 includes a motor for running the vehicle.

The control unit 12 comprehensively controls the operation of the fuel cell system 11 as a whole. The control unit 12 is configured by an ECU (Electronic Control Unit). In addition to flow rate sensor 47, pressure sensor 48, cell monitor 71 and DC/DC converter 75, control unit 12 electrically connects injector 37, pressure sensor 39, temperature sensor 51, exhaust/drain valve 61 and hydrogen pump 65, respectively. connected (see symbols A, B, C, D, E, F in FIG. 1). Injector 37 , exhaust/drain valve 61 , hydrogen pump 65 and DC/DC converter 75 operate based on commands given from controller 12 .

In the fuel cell system 11 configured as described above, the hydrogen supplied to the fuel cell stack 15 by the hydrogen supply unit 31 and the oxygen contained in the air supplied to the fuel cell stack 15 by the air supply unit 32 are combined into fuel cells. The fuel is distributed and supplied to each fuel cell 16 within the stack 15 . At that time, hydrogen is supplied to the anode side of the fuel cell 16 and oxygen is supplied to the cathode side of the fuel cell 16 . As a result, the fuel cell 16 generates electricity through an electrochemical reaction between hydrogen and oxygen.

Next, a method for controlling the output of the fuel cell stack in the fuel cell system will be explained using FIG.
First, the output state of the fuel cell stack 15 has four stages, a power generation stop state, a low output state, a medium output state, and a high output state, depending on the difference in the power generated by the fuel cell stack 15 . The power generation stop state is a state in which the fuel cell stack 15 stops power generation. The low output state is a state in which the fuel cell stack 15 outputs low generated power. The medium output state is a state in which the fuel cell stack 15 outputs a higher generated power than in the low output state, and the high output state is a state in which the fuel cell stack 15 outputs higher generated power than in the medium output state. is in a state of

The output state of the fuel cell stack 15 is switched step by step by the control unit 12 . In addition, the power generated by the fuel cell stack 15 is controlled by the controller 12 based on the command output required for each output state. For example, if the command output required in the medium output state is 6 (kW) and the command output required in the high output state is 12 (kW), the control unit 12 sets the output state of the fuel cell stack 15 to medium. When switching from the output state to the high output state, the fuel cell system 11 is controlled so that the actual output of the fuel cell stack 15 increases from 6 (kW) to 12 (kW). The actual output of the fuel cell stack 15 is the generated power that the fuel cell stack 15 actually outputs. The actual output of the fuel cell stack 15 can be measured by the controller 12 .

Further, when switching the output state of the fuel cell stack 15 , the control unit 12 feedback-controls the output of the fuel cell stack 15 based on the deviation between the command output and the actual output of the fuel cell stack 15 . Through this feedback control, the controller 12 operates the fuel cell system 11 so that the actual output of the fuel cell stack 15 matches the command output. The amount of hydrogen and air supplied to the fuel cell stack 15 and the pressure of hydrogen and air supplied to the fuel cell stack 15 are predetermined for each command output required for the fuel cell stack 15. ing. Therefore, when switching the output state of the fuel cell stack 15, the control unit 12 controls the operations of the air supply unit 32 and the hydrogen supply unit 31 according to the command output required in the output state after switching. At that time, the amount of air supplied to the fuel cell stack 15 is controlled by the air compressor 40, and the pressure of the air supplied to the fuel cell stack 15 is controlled by a pressure control valve provided in the air supply pipe. .

When the output of the fuel cell stack 15 is controlled as described above, an abnormal decrease in output may occur in the fuel cell stack 15 . In such a case, it is important to identify the cause of the abnormal drop in output of the fuel cell stack 15 so as to remove the cause as soon as possible and restore the fuel cell stack 15 to its normal state. Therefore, in this embodiment, the control method for the fuel cell system shown in FIG. 4 is adopted. This control method is executed by the control unit 12 .

First, the control unit 12 checks whether the average cell voltage Vm of the plurality of fuel cells 16 is below a predetermined voltage Va (step S11). Then, when the average cell voltage Vm is lower than the predetermined voltage Va, the process proceeds from step S11 to step S12. The average cell voltage Vm is obtained by integrating the cell voltages detected by the cell monitor 71 for each fuel cell 16 to obtain the total cell voltage. It is obtained by division. Predetermined voltage Va is set in advance to detect a drop in average cell voltage Vm.

Next, in step S12, the controller 12 checks whether the voltage difference ΔV between the fuel cells 16 is less than a predetermined value. If the voltage difference ΔV between the cells is equal to or greater than the predetermined value, the process returns to step S11, and if the voltage difference ΔV between the cells is less than the predetermined value, the process proceeds to step S13. Regarding the voltage difference ΔV between each cell, the maximum cell voltage and the minimum cell voltage are extracted from the cell voltages detected by the cell monitor 71 for each fuel cell 16, and the difference between the maximum cell voltage and the minimum cell voltage is calculated. , the voltage difference ΔV between the cells. Alternatively, the difference between the average cell voltage and the maximum cell voltage or the difference between the average cell voltage and the minimum cell voltage may be specified as the voltage difference ΔV between cells.

Next, in step S13, the control unit 12 determines whether or not the fuel cell stack 15 has abnormally decreased in output. At that time, the control unit 12 determines whether or not an abnormal decrease in output has occurred in the fuel cell stack 15 by confirming the following two items.

First, the controller 12 checks whether the deviation between the command output and the actual output of the fuel cell stack 15 is equal to or greater than a threshold. Then, if the deviation between the commanded output and the actual output of the fuel cell stack 15 is equal to or greater than the threshold, the following items are checked. The deviation between the command output and the actual output of the fuel cell stack 15 (hereinafter also referred to as "output deviation") is obtained by subtracting the actual output of the fuel cell stack 15 from the command output required of the fuel cell stack 15. be done. At this time, when the actual output of the fuel cell stack 15 is lower than the command output and the output deviation is equal to or greater than the threshold, the following matters, that is, when the output of the fuel cell stack 15 is feedback-controlled based on the output deviation, Check if the integral term is saturated. If the integral term of the feedback control is saturated, the controller 12 determines that an abnormal decrease in output has occurred in the fuel cell stack 15 and proceeds to step S14, otherwise returns to step S11. When the integral term of the feedback control is saturated, the integral value of the deviation is predetermined even though the control unit 12 is controlling the actual output of the fuel cell stack 15 to approach the command output. This is the state in which the specified upper limit has been reached. When the integral term of the feedback control becomes saturated, the actual output of the fuel cell stack 15 remains below the command output and enters a steady state, and under this steady state, the output deviation is maintained above the threshold. The control for bringing the actual output of the fuel cell stack 15 closer to the command output includes adjusting the amount of hydrogen and air supplied to the fuel cell stack 15, and adjusting the pressure and pressure of the hydrogen supplied to the fuel cell stack 15. It involves adjusting the air pressure.

Next, in step S14, the control unit 12 performs check processing. This check processing includes three steps S14a, S14b, and S14c. Note that the order of performing the three steps S14a, S14b, and S14c included in the check process can be arbitrarily changed.

Step S14a is a step of checking whether the amount of air supplied to the fuel cell stack 15 is appropriate. If the amount of air supplied to the fuel cell stack 15 is insufficient for the command output required of the fuel cell stack 15, the average cell voltage of the fuel cell stack 16 will drop, and the actual output of the fuel cell stack 15 will not reach the command output. stays below output. Therefore, an insufficient amount of air supplied to the fuel cell stack 15 can cause an abnormal decrease in the output of the fuel cell stack 15 . The check in step S<b>14 a is performed based on the detection result of the flow sensor 47 . Specifically, if the flow rate of air detected by the flow rate sensor 47 is equal to or greater than the reference flow rate corresponding to the command output of the fuel cell stack 15, the control unit 12 determines Yes in step S14a, and the flow rate reaches the reference flow rate. If not, it is judged as No. If the determination in step S14a is No, the process proceeds to step S15 to identify the cause of the abnormal decrease in output of the fuel cell stack 15. FIG. When the process proceeds from step S14a to step S15, the control unit 12 determines that insufficient air supply to the fuel cell stack 15 is the cause of the abnormal decrease in output of the fuel cell stack 15.

Step S14b is a step of checking whether the air supply pressure to the fuel cell stack 15 is appropriate. If the pressure of the air supplied to the fuel cell stack 15 is insufficient for the command output required of the fuel cell stack 15, the average cell voltage of the fuel cell 16 will drop, and the actual output of the fuel cell stack 15 will not reach the command output. stays below output. Therefore, insufficient pressure of the air supplied to the fuel cell stack 15 can cause an abnormal decrease in the output of the fuel cell stack 15 . The check in step S14b is performed based on the detection result of the pressure sensor 48. FIG. Specifically, if the air pressure detected by the pressure sensor 48 is equal to or higher than the reference pressure corresponding to the command output of the fuel cell stack 15, the control unit 12 determines Yes in step S14b, and the pressure reaches the reference pressure. If not, it is judged as No. If the determination in step S14b is No, the process proceeds to step S15 to identify the cause of the abnormal decrease in output of the fuel cell stack 15. FIG. When the process proceeds from step S14b to step S15, the control unit 12 determines that insufficient air supply pressure to the fuel cell stack 15 is the cause of the abnormal decrease in output of the fuel cell stack 15. FIG.

Step S14c is a step of checking whether the dryness of the fuel cell 16 is appropriate. In the fuel cell stack 15, by keeping the electrolyte membranes of the fuel cells 16 in a wet state, good gas diffusion to the electrolyte membrane is maintained. On the other hand, when the fuel cell 16 dries, the average cell voltage drops due to the rise in resistance overvoltage, and the actual output of the fuel cell stack 15 remains below the command output. Therefore, the drying of the fuel cell 16 can cause an abnormal decrease in the output of the fuel cell stack 15 . The check in step S<b>14 c is performed based on the impedance of the fuel cell stack 15 . The impedance of the fuel cell stack 15 corresponds to the membrane resistance of the electrolyte membrane of the fuel cell 16, and increases as the fuel cell 16 dries up. Therefore, the control unit 12 measures the impedance of the fuel cell stack 15 to check the dryness of the fuel cell 16 . Then, if the measured impedance is equal to or less than a predetermined reference impedance, it is determined as Yes in step S14c, and if it exceeds the reference impedance, it is determined as No. If the determination in step S14c is No, the process proceeds to step S15 to identify the cause of the abnormal decrease in output of the fuel cell stack 15. FIG. When the process proceeds from step S14c to step S15, the control unit 12 determines that the fuel cell stack 15 abnormally decreased in output was caused by the fuel cell 16 being dry. Regarding the measurement of the impedance of the fuel cell stack 15, an impedance measurement unit (not shown) may be provided separately from the control unit 12, and the results measured by this impedance measurement unit may be taken into the control unit 12.

If the air supply amount, the air supply pressure, and the dryness of the fuel cell 16 are all appropriate in the check process of step S14 described above, the process proceeds to step S16. In step S16, the control unit 12 presumes that the abnormal decrease in output of the fuel cell stack 15 is caused by the gas that inhibits the catalytic reaction of the fuel cell 16 being supplied to the fuel cell stack 15 together with air. . As a gas that inhibits the catalytic reaction of the fuel cell 16, for example, a gas volatilized from an organic solvent can be considered. If this type of gas exists around the fuel cell system 11, the gas is fed into the fuel cell stack 15 together with air when the compressor 40 of the air supply unit 32 is driven. As a result, the catalyst of each fuel cell 16 is poisoned, the average cell voltage drops, and the actual output of the fuel cell stack 15 remains below the command output. Therefore, if the gas that inhibits the catalytic reaction of the fuel cell 16 is sent into the fuel cell stack 15 together with the air, it may cause an abnormal decrease in the output of the fuel cell stack 15 . Further, in the check processing in step S14 performed before step S16, it is confirmed that the air supply amount, the air supply pressure, and the dryness of the fuel cell 16 are all appropriate. For this reason, as a case in which the fuel cell stack 15 abnormally lowers in output due to other causes, a case in which a gas that inhibits the catalytic reaction of the fuel cell 16 is sent into the fuel cell stack 15 is assumed. Therefore, based on the result of the check process, the control unit 12 detects that the gas that inhibits the catalytic reaction of the fuel cell 16 was sent into the fuel cell stack 15 together with the air. presumed to be the cause of

As described above, in the embodiment of the present invention, when an abnormal output drop occurs in the fuel cell stack 15, the step of checking whether the amount of air supplied to the fuel cell stack 15 is appropriate; A check process including a step of checking whether the air supply pressure to the stack 15 is appropriate and a step of checking whether the dryness of the fuel cells 16 is appropriate is performed. Then, in the check process, when the amount of air supplied, the supply pressure of air, and the dryness of the fuel cell 16 are all appropriate, the gas that inhibits the catalytic reaction of the fuel cell 16 is present together with the air in the fuel cell. It is presumed that the fuel cell stack 15 was fed into the fuel cell stack 15 and caused the abnormal output drop. As a result, if the cause of the decrease in the output of the fuel cell stack 15 is other than insufficient air supply to the fuel cell stack 15, insufficient air supply pressure, or drying of the fuel cell 16, the cause can be estimated after the check process. Therefore, the cause of the decrease in the output of the fuel cell stack 15 can be narrowed down more than before. Then, when an abnormal decrease in the output of the fuel cell stack 15 occurs due to the presence of a gas that inhibits the catalytic reaction of the fuel cell 16, the surrounding environment of the fuel cell system 11, for example, fuel An investigator can quickly identify the cause of the decrease in output by investigating whether or not work involving organic solvents is being performed near the operating location of the battery system 11 .

Further, in the embodiment of the present invention, the deviation between the command output and the actual output of the fuel cell stack 15 is equal to or greater than a threshold, and the integral term is used when the output of the fuel cell stack 15 is feedback-controlled based on the deviation. is in a saturated state, it is determined that an abnormal decrease in output has occurred in the fuel cell stack 15 . As a result, when the output of the fuel cell stack 15 is increased by feedback control, a transient output shortage during control will not be misidentified as an abnormal decrease in output. Therefore, the check process can be executed at necessary and appropriate timing.

Further, in the embodiment of the present invention, when the average cell voltage of the plurality of fuel cells 16 is below the allowable voltage and the voltage difference between the fuel cells 16 is less than a predetermined value, the fuel A determination is made as to whether or not the battery stack 15 has experienced an abnormal drop in output. As a result, it is possible to determine whether or not there is an abnormal decrease in the output of the fuel cell stack 15 when the cell voltages of the plurality of fuel cells 16 forming the fuel cell stack 15 are uniformly decreased.

It should be noted that the technical scope of the present invention is not limited to the above-described embodiments, and includes forms with various modifications and improvements within the range where specific effects obtained by the constituent elements of the invention and their combinations can be derived. .

For example, in the above-described embodiment, the case where the output state of the fuel cell stack 15 is switched in a plurality of stages for control has been described as an example, but the present invention is not limited to this. That is, the present invention may be applied to the case of steplessly controlling the output state of the fuel cell stack 15 .

Further, in the above embodiment, it is checked whether or not the average cell voltage Vm of the plurality of fuel cells 16 is lower than the predetermined allowable voltage Va, but the present invention is not limited to this. It may be checked whether the total cell voltage obtained by accumulating the cell voltages is below a predetermined allowable total cell voltage.

Further, in the above embodiment, the deviation between the command output and the actual output of the fuel cell stack 15 is equal to or greater than the threshold, and the integral term is saturated when the output of the fuel cell stack 15 is feedback-controlled based on the deviation. Although it is determined that an abnormal output decrease has occurred in the fuel cell stack 15 when the fuel cell stack 15 is in this state, the present invention is not limited to this. That is, as another example, when the output voltage of the fuel cell stack 15 is lower than a preset reference voltage and this state continues beyond a preset reference time, an abnormal output to the fuel cell stack 15 is detected. It may be determined that a decline has occurred.

In the above embodiment, the dryness of the fuel cell 16 is checked based on the impedance of the fuel cell stack 15, but the present invention is not limited to this. That is, since the temperature of the fuel cells 16 tends to increase as the drying of the fuel cells 16 progresses, the degree of dryness of the fuel cells 16 may be checked based on the temperature of the fuel cells 16 . In that case, the temperature of the fuel cell 16 is reflected in the temperature of cooling water flowing through the pipe 52 of the cooling unit 44 . Therefore, the temperature of the fuel cell 16 can be detected using the temperature sensor 51 of the cooling unit 44 .

11 fuel cell system, 12 control unit, 15 fuel cell stack, 16 fuel cell, 47 flow sensor, 48 pressure sensor, 51 temperature sensor, 71 cell monitor.

Claims (5)

A control method for a fuel cell system comprising a fuel cell stack having a plurality of fuel cells, comprising:
When an abnormal output decrease occurs in the fuel cell stack,
checking whether the amount of air supplied to the fuel cell stack is proper;
checking whether the air supply pressure to the fuel cell stack is proper;
checking whether the dryness of the fuel cell is proper;
Perform check processing including
In the check process, if the amount of air supplied, the supply pressure of air, and the dryness of the fuel cells are all appropriate, the gas that inhibits the catalytic reaction of the fuel cells is added together with the air. Presuming that being sent to the fuel cell stack is the cause of the abnormal output decrease of the fuel cell stack,
A control method for a fuel cell system. When the deviation between the command output and the actual output of the fuel cell stack is equal to or greater than a threshold value, and when the integral term when feedback-controlling the output of the fuel cell stack based on the deviation is in a saturated state, the fuel Determining that an abnormal output drop has occurred in the battery stack,
The control method of the fuel cell system according to claim 1. When the average cell voltage of the plurality of fuel cells is below a predetermined allowable voltage and the voltage difference between the fuel cells is below a predetermined value, an abnormal output drop occurs in the fuel cell stack. determine whether or not it has occurred,
3. A control method for a fuel cell system according to claim 1 or 2. checking the dryness of the fuel cell based on the impedance of the fuel cell stack;
A control method for a fuel cell system according to any one of claims 1 to 3. checking the dryness of the fuel cell based on the temperature of the fuel cell;
A control method for a fuel cell system according to any one of claims 1 to 3.

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