JP2017016974A - Control device for fuel battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To more reliably prevent corrosion of a separator, caused by generation of over-voltage in the start of a fuel battery.SOLUTION: A control device for a fuel battery comprises: a fuel battery body 1 comprising an anode 2 and a cathode 3 with an electrolyte 6 between them; fuel gas supply means that supplies fuel gas to the anode 2; oxidant-gas supply means that supplies oxidant gas to the cathode 3; voltage detection means 14 that detects a voltage generated in the fuel battery body 1; and fuel-gas supply control means 32 that adjusts fuel gas supplied to the fuel battery body 1 on the basis of a detection voltage detected by the voltage detection means 14. The fuel gas supply control means 32 exerts control such an instruction value for supply of fuel gas is set to a target supply value, a, at startup and, when the detection voltage is or may be higher than a predetermined determination voltage, b, an instruction value for supply of fuel gas is set to a first instruction value, d, smaller than the target supply value, a.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a fuel cell control device that controls start and stop of a fuel cell.

  A fuel cell has a mechanism for extracting electric energy from between electrodes provided on both sides of an electrolyte by reacting a fuel gas containing hydrogen and an oxidant gas containing oxygen.

  The cell constituting the fuel cell main body is supplied with a fuel electrode (anode) as an electrode to which fuel gas is supplied on one side of an electrolyte membrane made of an electrolyte, and with an oxidant gas on the other side. An air electrode (cathode) which is an electrode on the side to be formed is disposed. Further, a metal separator is disposed on the outside of each electrode.

Fuel gas is supplied to the anode side of the cell and oxidant gas is supplied to the cathode side, and power generation is performed by the following reaction to generate a cell voltage. Usually, hydrogen gas is used as the fuel gas, and air is used as the oxidant gas (see, for example, Patent Documents 1 and 2).
Anode: H ₂ → 2H ⁺ + 2e ⁻
Cathode: 2H ⁺ + 2e ⁻ + (1/2) O ₂ → H ₂ O

JP 2005-158557 A JP 2002-116402 A

  When the fuel cell is started, the cell voltage rises due to the introduction of the fuel gas or oxidant gas, and then stabilizes at the open circuit voltage. However, an overvoltage condition that temporarily exceeds the open circuit voltage may occur before the voltage stabilizes at the open circuit voltage.

  When the cell voltage becomes an overvoltage exceeding the open circuit voltage and the voltage exceeds the separator's overpassive potential, the passivation is regenerated on the surface of the separator as the cell voltage subsequently decreases. However, since the passive generation rate is relatively slow, the separator may be easily corroded if a sufficient generation time cannot be secured. Therefore, as shown in Patent Document 1, there is a technique for suppressing overvoltage by controlling a load.

  However, if the load control is stopped immediately after the voltage reaches the open circuit voltage due to suppression of the overvoltage by the load, the voltage may rise again and an overvoltage may occur again. Such a re-rise in voltage makes it difficult to ensure a passivating time. For this reason, it leads to corrosion of the separator, which is not preferable.

  In addition, as shown in Patent Document 2, when the cell voltage is reduced to an overvoltage determination voltage or less by controlling the load, the supply of oxidant gas (air) is controlled in conjunction with the load, thereby reducing the voltage. A control method is also conceivable. Here, the supply amount of the oxidant gas is controlled and the supply amount of the fuel gas is not controlled. Increasing or decreasing the supply amount of the fuel gas is a response from the increase / decrease instruction until the supply amount is actually increased or decreased. It is thought that this is because it is bad. On the other hand, since the response of the cell voltage to the change in the supply amount of the oxidant gas is relatively fast, there is a possibility that the voltage drop will overshoot due to the reduction in the gas supply amount, and the voltage will drop more than necessary. Further, when the load-linked responsiveness is increased in order to prevent this, the cell voltage rises faster, which may increase the risk of occurrence of overvoltage.

  Accordingly, an object of the present invention is to more reliably prevent the corrosion of the separator due to the occurrence of an overvoltage at the time of starting the fuel cell.

  In order to solve the above problems, the present invention provides a fuel cell body having an anode on one side and a cathode on the other side with an electrolyte interposed therebetween, fuel gas supply means for supplying fuel gas to the anode, and oxidation on the cathode An oxidant gas supply means for supplying an oxidant gas; a voltage detection means for detecting a voltage generated in the fuel cell main body by a reaction between the fuel gas and the oxidant gas; and a detection voltage detected by the voltage detection means. Fuel gas supply control means for adjusting the fuel gas supplied to the fuel cell main body based on the fuel gas supply control means, the fuel gas supply control means sets the instruction value of fuel gas supply to a target supply amount at startup, When the detected voltage exceeds or is expected to exceed the predetermined determination voltage, first control is performed to set the fuel gas supply instruction value to a first instruction value smaller than the target supply amount. Employing a control apparatus for a fuel cell.

  In this case, the fuel gas supply control means sets the fuel gas supply instruction value to a second value larger than the target supply amount after the detection voltage drops and falls below a predetermined transition voltage by the first control. It is possible to employ a configuration that performs the second control that is set to the indicated value.

  In each configuration for performing the first control, a load device that suppresses a voltage generated in the fuel cell main body by applying a load, and the fuel cell main body is applied based on a detection voltage detected by the voltage detection means. Load control means for adjusting a load, and the load control means adopts a configuration that applies a load when the detected voltage exceeds or is expected to exceed a predetermined determination voltage in the first control. can do.

  Here, in the first control, after the detection voltage drops and falls below a predetermined transition voltage, in the second control, the decrease of the load is temporarily stopped and the maximum load in the first control is exceeded. It is possible to adopt a configuration in which a load continuation period in which a low load is continuously applied is set.

  Alternatively, in the first control, after the detection voltage drops and falls below a predetermined transition voltage, it is possible to employ a configuration in which a no-load period for setting the load to zero is set in the second control. .

  The predetermined transition voltage may be set equal to the predetermined determination voltage.

  Further, after the start of the second control, it is possible to adopt a configuration in which the load control unit performs the load control again to increase the applied load again.

  The load applied in the second load control is preferably set so that the amount of increase in the detected voltage per unit time is equal to or less than a predetermined amount of increase.

  The present invention can more reliably prevent the corrosion of the separator due to the occurrence of overvoltage at the time of starting the fuel cell.

The schematic diagram which shows the structure of the control apparatus of the fuel cell which shows one Embodiment of this invention Graph showing an example of control at the start of the fuel cell Graph showing another example of control at startup of the fuel cell A graph showing still another example of control at the time of starting the fuel cell

  Embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a schematic diagram showing a configuration of a control device for a fuel cell according to this embodiment.

  In a fuel cell main body (cell) 1, an anode 2 and a cathode 3 are disposed between a pair of separators 4 and 5 so as to face each other with an electrolyte 6 interposed therebetween.

  In the fuel cell body 1, an electrochemical reaction proceeds between the hydrogen gas supplied to the anode 2 and the air supplied to the cathode 3 to generate power. The chemical reaction formula is as described above.

  As shown in FIG. 1, fuel gas supply means A for supplying hydrogen gas as fuel gas to the anode 2 is provided. The fuel gas supply means A includes a hydrogen tank 7, a hydrogen pressure adjustment valve 8, and a hydrogen injector 9 in order from the upstream side along the inflow-side anode-side pipe 21 connected to the fuel cell main body 1. In addition, a purge valve 10 is provided in the anode side piping 22 on the outflow side drawn out from the fuel cell main body 1.

  The supply of hydrogen gas from the hydrogen tank 7 to the anode 2 is adjusted by a hydrogen pressure adjustment valve 8. Since the hydrogen gas in the hydrogen tank 7 is at a high pressure, a pressure reducing valve or the like is appropriately interposed in the anode side pipe 21. The hydrogen gas remaining without being consumed at the anode 2 is returned to the anode side pipe 21 by the hydrogen circulation pump 26 through the circulation passage 25 branched from the anode side pipe 22 on the upstream side of the purge valve 10, and is returned to the fuel cell body 1 again. Circulating.

  The pressure detected by the pressure sensor 18 provided in the anode 2 is transmitted to the fuel gas supply control means 32 provided in the controller (control unit) 30. The fuel gas supply control means 32 controls the supply of hydrogen gas by the fuel gas supply means A based on the information. This control can be performed, for example, by feedback control based on elements of the set pressure and the actual pressure.

  The fuel gas supply means A controls so that the pressure of the hydrogen gas in the anode 2 is always constant. In other words, control for automatically supplementing the hydrogen gas consumed in the fuel cell main body 1 is performed. The purge valve 10 discharges the hydrogen in the anode 2 when the fuel cell is stopped. The purge valve 10 also discharges other substances such as nitrogen in the anode 2 in order to increase the partial pressure of hydrogen in the anode 2 during operation of the fuel cell, and recovers the cell voltage. The water droplets in the flow path can also be discharged.

  Further, as shown in FIG. 1, an oxidant gas supply means B for supplying air as an oxidant gas to the cathode 3 is provided. The oxidant gas supply means B includes the compressor 11 in the inflow side cathode side pipe 23 connected to the fuel cell main body 1. The cathode side pipe 24 on the outflow side drawn out from the fuel cell main body 1 is provided with an air pressure adjusting valve 12.

  The supply of air to the cathode 3 is adjusted by the compressor 11. The pressure detected by the pressure sensor 19 provided on the cathode 3 is transmitted to the oxidant gas supply control means 33 provided in the controller 30. The oxidant gas supply control means 33 controls the air supply by the oxidant gas supply means B based on the information. This control can be performed, for example, by feedback control based on elements of the set pressure and the actual pressure.

  The oxidant gas supply means B controls so that the pressure of the air in the cathode 3 is always constant. That is, control is performed to automatically supplement the air (oxygen) consumed in the fuel cell main body 1.

  Between the fuel cell main body 1 and the controller 30, a power supply circuit C which is a power extraction circuit is provided. The power supply circuit C includes a load device 13 that suppresses a voltage generated in the fuel cell main body 1 by applying a load to the fuel cell main body 1. As the load device 13, for example, a fixed resistor, a storage battery, a DC voltage converter (DC-DC converter), or the like can be adopted. When a load current flows from the fuel cell main body 1 to the load device 13, hydrogen gas on the anode 2 side and oxygen in the air on the cathode 3 side are consumed, and the voltage of the fuel cell main body 1 temporarily decreases.

  Further, a voltage detection means 14 for detecting a voltage generated in the fuel cell main body 1 due to a reaction between the fuel gas and the oxidant gas is provided between the fuel cell main body 1 or between the fuel cell main body 1 and the controller 30. It is done. In this embodiment, the voltage detection means 14 is a voltage sensor.

  The load applied to the power supply circuit C including the fuel cell main body 1 by the load device 13 is controlled by a load control means 31 provided in the controller 30. The load control unit 31 adjusts the load applied to the fuel cell body 1 by the load device 13 based on the detection voltage detected by the voltage detection unit 14. The adjustment of the load is performed by feedback control or the like. By adjusting the load, the voltage generated in the fuel cell body 1 increases or decreases. The increase / decrease can be detected by the voltage detection means 14 at any time. In addition, the voltage value and the current value in the power supply circuit C after the load is applied can be confirmed by the voltmeter 15 and the ammeter 16.

  Further, the fuel cell main body 1 is provided with temperature detection means 17 for detecting the temperature of the fuel cell main body 1. In this embodiment, the temperature detection means 17 is a temperature sensor.

  This fuel cell control device includes fuel gas supply control means 32 that adjusts the fuel gas supplied to the fuel cell main body 1 based on the detection voltage detected by the voltage detection means 14. Further, an oxidant gas supply control means 33 for adjusting the oxidant gas supplied to the fuel cell main body 1 based on the detected voltage is provided. The fuel gas supply control means 32 and the oxidant gas supply control means 33 are provided in the controller 30.

  When this fuel cell control device is mounted on, for example, a vehicle, the controller 30 takes out electric power from the fuel cell main body 1 through the power supply circuit C during power generation in the fuel cell main body 1, Power is supplied to the power consuming device 20 that consumes power such as a driving motor. In particular, the voltage of the fuel cell body 1 is adjusted by increasing / decreasing the value of the load applied to the power supply circuit C by the load device 13 at the time of starting the previous stage of using the power consuming device 20. Even when the power consuming device 20 is in use, the voltage of the fuel cell body 1 is adjusted by increasing or decreasing the value of the load applied to the power supply circuit C by the load device 13 according to the target voltage.

  Note that a vehicle equipped with this fuel cell control device selects, for example, a secondary battery having a plug-in charging mechanism that can be charged by connection to an external power source, and the aforementioned fuel cell as a power source. Configuration that can be used in an automated manner. A secondary battery and a fuel cell are arranged in parallel to the motor and the inverter.

  Hereinafter, control of the fuel cell of the present invention will be described.

(Example of control in FIG. 2)
First, an example of the control shown in FIG. 2 will be described. The fuel cell is started and fuel gas and oxidant gas are supplied to the fuel cell main body 1. The voltage generated in the fuel cell body 1 gradually increases as shown in the upper graph in the figure. At this time, the indicated value of the hydrogen supply amount is a target supply amount a which is a predetermined target value until the voltage stabilizes from the time of startup as well as after the stabilization, as shown in the lower part of the figure. Set to.

  The load control unit 31 applies a load when the detection voltage detected by the voltage detection unit 14 exceeds or is expected to exceed the predetermined determination voltage b. The graph shown in the middle part of FIG. 2 is the transition of the applied load.

  Here, the application of the load is started simultaneously with the detection voltage reaching the predetermined determination voltage b, but the application of the load reaches the predetermined determination voltage b after the detection voltage exceeds the predetermined determination voltage b. After that, it may be started at a timing after a certain time has elapsed. However, in this case, it is desirable that the load be applied as soon as possible after the detected voltage exceeds the predetermined determination voltage b. Further, the transition of the voltage value up to now and other factors such as the supply amount of the fuel gas and the oxidant gas are predicted, and then the transition of the voltage value is predicted, and the detected voltage is expected to exceed the predetermined determination voltage b. If it is determined, the application of the load may be started even before the detected voltage actually exceeds the predetermined determination voltage b.

  As the load is applied, the detection voltage decreases, is kept constant, or the increase degree is suppressed. In FIG. 2, the detection voltage is kept constant at the predetermined determination voltage b after exceeding the predetermined determination voltage b or after reaching the predetermined determination voltage b. During this time, the load necessary for suppressing the detection voltage gradually decreases. The decrease in the applied load is as shown in the graph in the middle of FIG. Here, the applied load is gradually decreased with the maximum load P1 being the peak value as a boundary so that the detection voltage is kept constant at the predetermined determination voltage b. Control of these loads is referred to as first load control. As the predetermined determination voltage b, an appropriate voltage value is determined from the viewpoint of protecting the separator in the fuel cell main body 1.

  After the detection voltage drops and the detection voltage falls below the predetermined transition voltage c, the load reduction is temporarily stopped. The first load control is until the load decrease is stopped. Here, the same voltage value as the predetermined determination voltage b is adopted as the predetermined transition voltage c when the load decrease is temporarily stopped. However, the predetermined transition voltage c is a value slightly larger than the predetermined determination voltage b. Alternatively, it may be a value slightly smaller than the predetermined determination voltage b. The predetermined transition voltage c should be set to an appropriate voltage value from the viewpoint of protecting the separator in the fuel cell main body 1, and at the same time, from the viewpoint of the behavior of subsequent voltage fluctuation, the voltage does not drop or rises. It can set suitably so that it may not do too much.

  After stopping the decrease of the load, the applied load is kept constant at a value of P2, which is a load value relatively lower than the maximum load P1 in the first load control. The constant load P2 is continuously applied for a certain period. The duration of the load P2 is referred to as a load duration. After the end of the load continuation period, the load is reduced to approach zero. As a result, the voltage is stabilized at the open circuit voltage which is the target value. This control is referred to as second load control.

  Here, the load applied during the load continuation period is set to a constant load value P2. However, the load may not necessarily be a constant load, and depending on the state of voltage fluctuation, It may be accompanied by an increase or decrease.

  The length of the load continuation period is determined based on the temperature detected by the temperature detection means 17. The higher the temperature of the fuel cell body 1, the longer the load duration period is set, and the lower the temperature of the fuel cell body 1, the shorter the load duration period.

  However, when the detected voltage falls below the predetermined minimum voltage after the start of the second load control, the application of the load is stopped. The predetermined minimum voltage can be set to a lower limit value in which, for example, it is not preferable that the voltage is further lowered when the voltage smoothly reaches the target open circuit voltage. The predetermined minimum voltage can be set to a voltage corresponding to the occurrence of an abnormality, for example.

  In the above control example, in the first load control scene, the control for reducing the supply amount of the hydrogen gas as the fuel gas may be performed together. Here, the fuel gas supply control means 32 sets the instruction value of fuel gas supply to the target supply amount a at the time of start-up, and the detection voltage exceeds or is expected to exceed the predetermined determination voltage b in the first load control. In this case, the fuel gas supply instruction value is set to a first instruction value d (see the control example in FIG. 3 described later) that is smaller than the target supply amount a. Along with the suppression of the supply of fuel gas, the detection voltage is quickly decreased, maintained constant, or the increase degree is quickly suppressed by a synergistic effect with the load application.

  Further, in the above control example, in the second load control scene, the control for increasing the supply amount of the hydrogen gas as the fuel gas may be performed together. Here, the fuel gas supply control means 32 sets the instruction value for fuel gas supply to a second instruction value e (see the control example in FIG. 3 described later), which is larger than the target supply amount a. As the instruction value increases, the detection voltage quickly stabilizes at the open circuit voltage that is the target value due to a synergistic effect with the application of the load.

(Example of control in FIG. 3)
Next, an example of the control shown in FIG. 3 will be described. Similarly, the fuel cell is started and fuel gas and oxidant gas are supplied to the fuel cell main body 1. The voltage generated in the fuel cell body 1 gradually increases as shown in the upper graph in the figure.

  The load control unit 31 applies a load when the detection voltage detected by the voltage detection unit 14 exceeds or is expected to exceed the predetermined determination voltage b. The graph shown in the middle part of FIG. 3 is the transition of the applied load. As the load is applied, the detection voltage decreases, is kept constant, or the increase degree is suppressed.

  Here, the application of the load is started at the same time when the detected voltage exceeds the predetermined determination voltage b, but the application of the load is performed at a timing after a certain time has elapsed after the detection voltage exceeds the predetermined determination voltage b. The points that may be started are the same as in the control example described above.

  Further, in this control example, in addition to the above-described load control, the instruction value for the hydrogen supply amount is set to the target supply amount a at the time of start-up, as shown in the lower part of the figure, and detected. When the voltage exceeds or is expected to exceed the predetermined determination voltage, the fuel gas supply instruction value is set to the first instruction value d smaller than the target supply amount a. In the first control, the load is controlled and the supply amount of the fuel gas is controlled. Here, the applied load is gradually decreased with the maximum load P1 being the peak value as a boundary so that the detection voltage is kept constant at the predetermined determination voltage b. Further, the supply amount of the fuel gas approaches the instruction value with a slight time lag as the instruction value is changed. Along with the suppression of the supply of fuel gas, the detection voltage is quickly decreased, maintained constant, or the increase degree is quickly suppressed by a synergistic effect with the load application.

  The detection voltage is maintained at the predetermined determination voltage b by controlling the load and the supply amount of the fuel gas, and then the load is set to zero when the detection voltage falls below the predetermined determination voltage b. The setting of the first instruction value d for the fuel gas supply is also released. The first control is until the stop of the load application and the release of the first instruction value d. In the graph shown in the upper part of FIG. 3, the alternate long and short dash line indicates the transition of voltage assumed when neither load control nor fuel gas supply amount control is performed. A broken line is a transition of a voltage assumed when only load control of fuel gas is performed without performing load control.

  After stopping the application of the load and ending the first control, the second control is performed. In the second control, the fuel gas supply control means 32 sets the fuel gas supply instruction value to a second instruction value e that is larger than the target supply amount a. The second instruction value e can be set smaller as any of these numerical values is higher based on the temperature of the fuel cell main body 1, the outside air temperature, the outside air humidity, and the like. The detected voltage gradually increases with the setting of the second instruction value e that is larger than the target supply amount a. However, as it is, the voltage may behave more than the open circuit voltage, which is the target value, as in the upper thin line in FIG. 3 (see the line without reload control).

  Therefore, in the second control, reload control (reload control) is performed as the voltage increases. In the reload control, the value of P3, which is a load value relatively lower than the maximum load P1 in the first control, is maximized, and the load is increased or decreased so that the voltage approaches the target open circuit voltage. Is done. The reload control may be set to be performed when the detected voltage exceeds or is expected to exceed the predetermined determination voltage b, or when the detected voltage does not reach the predetermined determination voltage b. It may be set for the purpose of early stability. When the voltage stabilizes to the open circuit voltage, the reload control is terminated.

  The load applied in this reload control can be set so that the amount of increase in the detected voltage per unit time is less than or equal to the predetermined amount of increase. That is, in order to prevent the voltage from rising rapidly, an upper limit of a predetermined increase amount is set for the increase amount per unit time.

  However, when the detected voltage falls below the predetermined minimum voltage after the start of the second control, the point of stopping the load application is the same as in the above-described control example.

  In the control example of FIG. 3, the load control in the first control and the second control is omitted, and the indication value of the supply amount of the hydrogen gas as the fuel gas is set to the target supply amount a and the first indication. It may be possible to cope with the early stabilization of the voltage only by control to increase or decrease the value d and the second instruction value e.

(Example of control in FIG. 4)
Next, an example of the control shown in FIG. 4 will be described. The example of the control in FIG. 4 is obtained by setting the aforementioned load duration in the second control after the end of the first control in addition to the example of the control in FIG. Hereinafter, a description will be given focusing on differences from the control example of FIG.

  In the first control, after the detected voltage drops and reaches the predetermined transition voltage c, in the second control, the load reduction is temporarily stopped and the load is lower than the maximum load P1 in the first control. The load P2 is continuously applied as the load continuation period. Here, the load applied during the load continuation period is set to a constant load value P2. However, the load may not necessarily be a constant load, and depending on the state of voltage fluctuation, It may be accompanied by an increase or decrease. The rise of the detection voltage is suppressed by setting the load duration.

  However, as in the control example of FIG. 3 described above, after the detection voltage drops and reaches the predetermined transition voltage c in the first control, in the second control, the load is not set without setting the load duration. It may be preferable to set a no-load period to zero. In the second control, the fuel gas supply instruction value is increased to the second instruction value e, but the fuel gas supply is decreased in the preceding stage, and the fuel gas supply actually increases. Since there is a time lag until this time, it is for suppressing that a voltage falls during the time lag. The supply of the fuel gas to the anode 2 is relatively quick in reducing the pressure, but is slow in increasing the pressure. Further, if the supply amount of fuel gas is increased or decreased, the voltage generated in the fuel cell body 1 may fluctuate. Therefore, the load is reduced to zero so that the voltage does not decrease excessively in response to such unintended fluctuation. Is set.

  Here, the value of the same voltage as the predetermined determination voltage b may be adopted as the predetermined transition voltage c when the load decrease is temporarily stopped, or a value slightly larger than the predetermined determination voltage b as the predetermined transition voltage c. Alternatively, it may be a value slightly smaller than the predetermined determination voltage b.

1 Fuel cell body (cell)
2 Fuel electrode (anode)
3 Air electrode (cathode)
4,5 Separator 6 Electrolyte 7 Hydrogen tank 8 Hydrogen pressure adjustment valve 9 Ejector 10 Purge valve 11 Compressor 12 Air pressure adjustment valve 13 Load device 14 Voltage sensor (voltage detection means)
15 Voltmeter 16 Ammeter 17 Temperature detection means 21, 22 Anode side piping 23, 24 Cathode side piping 30 Controller (control unit)
31 Load control means 32 Fuel gas supply control means 33 Oxidant gas supply control means

Claims (8)

A fuel cell body having an anode on one side and a cathode on the other side with an electrolyte interposed therebetween;
Fuel gas supply means for supplying fuel gas to the anode;
An oxidant gas supply means for supplying an oxidant gas to the cathode;
Voltage detection means for detecting a voltage generated in the fuel cell main body due to a reaction between the fuel gas and an oxidant gas;
Fuel gas supply control means for adjusting the fuel gas supplied to the fuel cell body based on the detection voltage detected by the voltage detection means;
With
The fuel gas supply control means sets a fuel gas supply instruction value to a target supply amount at the time of start-up, and if the detected voltage exceeds or is expected to exceed a predetermined determination voltage, the fuel gas supply instruction means A fuel cell control apparatus that performs a first control to set a value to a first instruction value that is smaller than a target supply amount. The fuel gas supply control means sets the fuel gas supply instruction value to a second instruction value larger than the target supply amount after the detection voltage drops by the first control and falls below a predetermined transition voltage. The fuel cell control device according to claim 1, wherein the second control to be set is performed. A load device for suppressing a voltage generated in the fuel cell main body by applying a load;
Load control means for adjusting a load applied to the fuel cell main body based on a detection voltage detected by the voltage detection means;
With
3. The fuel cell control device according to claim 1, wherein the load control unit applies a load when the detected voltage exceeds or is expected to exceed a predetermined determination voltage in the first control. 4. In the first control, after the detection voltage drops and falls below a predetermined transition voltage, in the second control, the load decrease is temporarily stopped and the load is lower than the maximum load in the first control. The fuel cell control device according to claim 3, wherein a load continuation period for continuously applying the load is set. 4. The fuel cell according to claim 3, wherein in the first control, after the detection voltage drops and falls below a predetermined transition voltage, a no-load period in which the load is zero is set in the second control. 5. Control device.   6. The fuel cell control device according to claim 4, wherein the predetermined transition voltage is set equal to the predetermined determination voltage. The fuel cell control device according to any one of claims 4 to 6, wherein, after the start of the second control, the load control unit performs load control again to increase the applied load again. The fuel cell control device according to claim 7, wherein a load applied in the second load control is set so that an increase amount of the detected voltage per unit time is equal to or less than a predetermined increase amount.

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