JP2013105534A - Fuel cell system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To supply just enough air to each cell when supplying air in preparation for a restart during an idle stop.SOLUTION: A fuel cell system includes: a voltage detection section 11 for detecting a cell voltage or a cell group voltage; a cell voltage processing section 21 for computing a voltage state on the basis of the detection result of the voltage detection section; a processing result determination section 22 for determining that the preceding value of air supply intermittently supplied to a cathode during an idle stop is excessive, deficient or appropriate on the basis of the processing result of the cell voltage processing section 21; and a supply air amount decision section 23 for deciding that an air supply amount be decreased from, increased from or maintained at a preset fixed value or the preceding supply amount in accordance with the determination result of the processing result determination section 22.

Description

  The present invention relates to air supply control of a fuel cell system.

  2. Description of the Related Art There is known a fuel cell vehicle that is equipped with a fuel cell and a secondary battery and travels by appropriately using these to supply power to a traveling motor. In such a fuel cell vehicle, in order to efficiently use the fuel gas, for example, when driving at a low load, the so-called idle stop is executed in which the power generation by the fuel cell is stopped and the motor is driven only by the secondary battery. There is a case.

  However, if the air supply to the fuel cell is continuously stopped during the idle stop, the voltage of the fuel cell decreases. The greater the voltage drop, the longer it takes to boost the voltage to the required voltage when restarting the fuel cell due to increased load or the like.

  Therefore, in Patent Document 1, air supply is performed when the voltage of the fuel cell decreases to a predetermined value during the idle stop, and the voltage of the fuel cell is recovered. This air supply is performed only for a preset period by a timer or the like.

Japanese Patent No. 4182732

  However, the configuration in which the air supply period is set in advance as in Patent Document 1 cannot cope with changes over time such as an increase in pressure loss due to filter clogging. For this reason, the case where it becomes impossible to flow the air quantity required for the voltage recovery during the idle stop may occur.

  By the way, conventionally, the variation in the voltage drop rate after stopping the air supply for idle stop has been considered to be mainly due to the variation in air distribution between cells. However, it has been found by the applicants that in practice, the variation in the voltage drop rate becomes large when the air supply amount is insufficient.

  Therefore, when the air supply amount is insufficient due to the configuration as in Patent Document 1, the variation in the voltage drop rate between the cells after the air supply is stopped increases. Then, when the voltage is greatly lowered and restarted according to the load increase to cause further voltage drop, a cell having a particularly large voltage drop speed may be diagnosed as being excessively dropped and may fall into the fail-safe mode.

  On the other hand, in the configuration as in Patent Document 1, an excessive amount of air may be supplied due to individual differences due to variations in the manufacturing process. For example, when control is performed so as not to exceed the upper limit voltage, the time during which current flows in order to maintain the upper limit voltage becomes longer. As a result, extra power is generated, and the amount of hydrogen consumption increases unnecessarily. On the other hand, when controlling to keep the current value during idle stop constant, the total voltage rises or the high voltage state continues for a long time due to excessive air flow. End up.

  Therefore, an object of the present invention is to provide a fuel cell system capable of supplying air to each cell without excess or deficiency when air is supplied in preparation for restart during idle stop.

  The fuel cell system of the present invention includes a voltage detection unit that detects a cell voltage or a cell group voltage, a cell voltage calculation unit that calculates a voltage state based on a detection result of the voltage detection unit, and an idle stop based on the calculation result A calculation result determination unit for determining whether or not the previous value of the air supply amount intermittently supplied to the cathode is excessive or insufficient is provided. Furthermore, a supply air amount determining unit that determines to decrease or increase the air supply amount with respect to a preset fixed value or the previous supply amount according to the determination result of the calculation result determination unit is provided.

  According to the present invention, it is determined whether the air supply amount during idle stop is excessive or insufficient based on the behavior of the cell voltage, and the air supply amount is corrected according to the determination result. It can be a supply amount.

It is a system configuration figure concerning a 1st embodiment. It is a control block diagram of the air supply control during the idle stop which concerns on 1st Embodiment. It is a flowchart of control of the air supply amount in 1st Embodiment. It is a table used for increase correction amount determination. It is another example of the block diagram of the system which concerns on 1st Embodiment. It is a time chart at the time of performing the control routine of FIG. It is a time chart for demonstrating the effect of this embodiment in the case of performing upper limit voltage control. It is a time chart for demonstrating the effect of this embodiment in the case of performing constant current control. It is a flowchart of control of the air supply amount in 2nd Embodiment. It is a control block diagram of the air supply control during idle stop which concerns on 3rd Embodiment. It is a flowchart of control of the air supply amount in 3rd Embodiment.

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

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

  The fuel cell stack 1 is a direct current power source and has a structure in which a plurality of single cells each having an electrolyte membrane 4 sandwiched between an anode 2 and a cathode 3 are stacked. FIG. 1 shows only a single cell.

  Hydrogen gas as fuel is supplied to the anode 2 from the hydrogen supply passage 7. Air as an oxidant gas is supplied to the cathode 3 from the air supply passage 8.

  The hydrogen supply passage 7 is provided with a pressure control valve (not shown). Thereby, the high-pressure hydrogen in the hydrogen tank 5 is supplied to the anode 2 after being depressurized to a predetermined pressure.

  Air is supplied from the air supply passage 8 to the cathode 3 by the compressor 6. The air pressure in the cathode 3 is controlled by an air pressure adjusting valve (not shown).

  The driving of the compressor 6 is controlled by the controller 9 based on the detection value of the rotation speed sensor 10 that detects the rotation speed of the compressor 6.

  The controller 9 includes a microcomputer having a central processing unit (CPU), a read only memory (ROM), a random access memory (RAM), and an input / output interface (I / O interface). The controller 9 can be composed of a plurality of microcomputers.

  Further, the controller 9 calculates the voltage of the fuel cell stack 1 and the average voltage of the single cell, and specifies the minimum voltage based on the detection value of the voltage sensor 11 provided in each cell as a voltage detection unit. In addition, a voltage sensor is installed for each cell group that is a set of a plurality of single cells, not for each cell, and the voltage of the fuel cell stack 1 and the average voltage of the cell group are calculated based on the cell group voltage. You may make it calculate specific etc.

  The fuel cell system configured as described above is mounted on a vehicle that travels using an electric motor as a drive source. In addition to the fuel cell stack 1, a secondary battery is also mounted on this vehicle. In addition to being used for driving the electric motor, the power generated by the fuel cell stack 1 is charged to the secondary battery. And the controller 9 controls the electric power supply from a fuel cell system or a secondary battery to an electric motor according to a driving | running state.

  For example, when the required power is low, such as during low-load running, the controller 9 temporarily stops the power generation of the fuel cell stack 1 and drives the electric motor, auxiliary equipment, etc. using only the power of the secondary battery. The so-called idle stop is executed. The idle stop ends when the charge amount of the secondary battery falls below a predetermined threshold or when the required power increases due to an acceleration request or the like.

  During the idle stop, the air supply to the cathode 3 is stopped, but oxygen remaining in the cathode 3 is consumed by reacting with hydrogen that has permeated the cathode 3, and the total stack voltage gradually decreases. . For this reason, the longer the idle stop duration time, the longer the time required for the stack total voltage to recover when returning from idle stop, and the greater the delay in response to an acceleration request or the like.

  Therefore, when the average voltage of the fuel cell stack 1 drops to the preset voltage V0 during the idle stop, the controller 9 supplies air to the cathode 3 in order to recover the voltage. The total voltage may be calculated, and air supply may be performed when the total voltage is reduced to a predetermined voltage.

  By the way, when the amount of air supplied to the fuel cell stack 1 is insufficient, the variation in the voltage drop rate between the single cells increases, and the difference between the lowest voltage in the stack and the decrease rate of the average cell voltage increases. That is, there is a strong correlation between the residual oxygen amount in the stack and the cell voltage. Therefore, the controller 9 performs air supply control during idle stop based on the cell voltage.

  FIG. 2 is a control block diagram showing an outline of air supply control executed by the controller 9 during idle stop.

  The detection value of the voltage sensor 11 is read into the cell voltage calculation unit 21, and the average voltage of the fuel cell stack 1 and the voltage of the cell having the lowest voltage in the stack (hereinafter referred to as the minimum voltage) are obtained. Based on the calculation result in the cell voltage calculation unit 21, the calculation result determination unit 22 determines whether the filling amount by air supply during idle stop is excessive, insufficient, or appropriate.

  On the other hand, the air supply amount calculation unit 24 calculates the air supply amount during idle stop based on the detection value of the rotation speed sensor 10.

  Then, the supply air amount determination unit 23 determines the next air supply amount based on the determination result of excess, deficiency, or appropriate and the calculation result of the air supply amount calculation unit 24, and controls the compressor 6. That is, it is determined whether or not the previous air supply amount is appropriate based on the voltage during idle stop, and the current air supply amount is corrected. Specific calculations and the like will be described with reference to FIG.

  FIG. 3 is a flowchart showing a control routine for determining the air supply amount, which is executed by the controller 9 during the air supply stop period during idling stop. This control routine is executed when the average voltage or the total voltage of the fuel cell stack 1 drops to the lower limit value for air supply start determination during the air supply stop period, that is, immediately before the start of air supply.

  In steps S100 and S110, the controller 9 reads the detection value of the voltage sensor 11, and calculates the average voltage AveCV and the minimum voltage MinCV of the fuel cell stack 1.

  In step S120, the controller 9 determines whether or not the minimum voltage MinCV is equal to or higher than the threshold value Vb. The threshold value Vb is a boundary value indicating whether or not the air supply amount is insufficient. When the minimum voltage MinCV is equal to or higher than the threshold value Vb, the process of step S130 is executed. When the minimum voltage MinCV is lower than the threshold value Vb, that is, when the air supply amount is insufficient, the process of step S150 is executed.

  Although the lowest voltage MinCV is compared with the threshold value Vb here, the next lowest cell voltage after the lowest voltage MinCV is obtained in step S110, and the Nth lowest voltage is compared with the threshold value Vb. Also good. That is, any cell voltage that can determine whether the air supply amount is excessive or insufficient is acceptable. The same applies to step S130 described later.

  In step S130, the controller 9 determines whether or not the minimum voltage MinCV is smaller than the threshold value Va. The threshold value Va is a boundary value indicating whether or not the air supply amount is excessive. If the minimum voltage MinCV is higher than the threshold value Va, the process of step S140 is executed. If the minimum voltage MinCV is less than the threshold value Va, that is, if the air supply amount is excessive, the process of step S160 is executed.

  In step S140, the controller 9 maintains the current air supply amount. This is because the previous air supply amount was appropriate.

  Note that the air supply amount is set to a value at least larger than the cathode active area volume at the first calculation after the system is started. The active area volume is obtained by multiplying the area of the reaction surface that contributes to power generation of each single cell by the height of the air flow path in contact with the reaction surface, and totaling this by the number of stacked cells. Includes pore volume. If air having an active area volume or more is supplied, a sufficient amount of air is supplied to all the single cells, and variations in the voltage drop rate between the single cells can be suppressed. As a result, it is possible to reduce the possibility of switching to the fail-safe mode due to a voltage drop of a specific single cell.

  In step S150, the controller 9 increases the supply amount. Specifically, the difference between the average voltage AveCV and the minimum voltage MinCV when it is determined whether or not it is insufficient is calculated, and the increase rate is set by searching, for example, a table as shown in FIG. Is used to correct the previous air supply. The vertical axis of FIG. 4 indicates the increase rate, and the horizontal axis indicates the difference between the average voltage AveCV and the minimum voltage MinCV. As shown in FIG. 4, the increase rate increases as the difference between the average voltage AveCV and the minimum voltage MinCV increases.

  In the region where the difference between the average voltage AveCV and the minimum voltage MinCV is extremely small, the increase rate is a negative value, that is, the amount is decreased. This region is a weight reduction region used when the minimum voltage MinCV is higher than the threshold value Va, that is, in step S160 described later. When the minimum voltage MinCV is lower than the threshold value Vb, it does not become a reduction area.

  In step S160, the controller 9 decreases the supply amount. Specifically, for example, a reduction rate is set by searching a table as shown in FIG. 4, and the previous air supply amount is corrected using this reduction rate.

  The above control routine is preferably performed immediately before the start of air supply from the viewpoint of improving control accuracy, but may be executed at any time during the air supply stop period. In this case, the threshold values Va and Vb need to be set according to the execution timing.

  Further, the target to be increased or decreased in step S150 or step S160 is not limited to the previous supply value. For example, a reference supply amount may be set as a fixed value, and this may be increased or decreased. In this case, the rotation speed sensor 10 and the air supply amount calculation unit 24 are not necessary. As shown in FIG. 5, a flow meter 31 may be disposed in the air supply passage 8 to directly detect the air flow rate.

  FIG. 6 is a time chart when the above control is executed.

  Here, the previous air supply is terminated at timing T1, and the period until timing T2 is the air supply stop section. When the air supply is stopped, the cell voltage starts decreasing, and when the average voltage AveCV reaches the threshold value V0 at the timing T2, the air supply is resumed. At this time, since the minimum voltage MinCV is lower than the threshold value Vb, the air supply amount from the timing T2 is corrected to increase based on the difference between the average voltage AveCV and the minimum voltage MinCV. As a result, air is supplied until timing T3.

  The determination of whether the previous supply amount is excessive or insufficient is ideally the timing T2 immediately before resuming the air supply, but it may be performed before this. However, when it is performed before the timing T2, it is necessary to set the thresholds Va and Vb according to this.

  Next, the effect of controlling the air supply amount as in this embodiment will be described.

  When the amount of air supplied to the fuel cell stack 1 is insufficient, the variation in the voltage drop rate between the single cells increases. That is, the difference in the decrease rate between the minimum voltage MinCV and the average cell voltage AveCV is increased.

  For this reason, when returning from the idle stop in a state where the voltage is lowered, the minimum voltage MinCV is significantly reduced due to further voltage drop due to resumption of power supply to the load. If there is a single cell with a significantly low cell voltage, the cell diagnosis device diagnoses that there is an abnormality and there is a risk of switching to the fail-safe mode.

  On the other hand, in this embodiment, the air supply amount during idle stop is controlled based on the cell voltage, so the air amount necessary for voltage recovery is supplied to each single cell, and the cell due to insufficient filling amount Variation in the voltage drop rate can be suppressed. As a result, as shown in FIG. 6, the variation in the voltage drop rate after timing T3 is reduced, and switching to the fail-safe mode as described above can be prevented.

  In addition, fuel efficiency can be improved by optimizing the air supply amount during idle stop. FIG. 7 is a time chart when the stack voltage of the fuel cell stack 1 is controlled so as not to exceed the upper limit value. Specifically, the stack voltage is prevented from exceeding the upper limit value by controlling the magnitude of the current. This is called upper limit voltage control. The upper limit value is set to a value that can prevent high potential deterioration. A time T1 in the figure is a supply time calculated based on an air supply amount necessary for voltage recovery at the time of design.

  Air supply is started at the timing T1 when the stack voltage is reduced to the lower limit voltage, and the stack voltage reaches the upper limit voltage at the timing T2. If the air flow rate is as designed, the air supply necessary for voltage recovery is supplied by continuing the air supply until timing T4. However, if more air flows than designed due to factors such as individual differences in parts, and supply of the amount of air necessary for voltage recovery is completed at timing T3, air is wasted from timing T3 to timing T4. , You will be wasted power generation. As a result, hydrogen is wasted. In addition, the amount of generated water increases and the possibility of water clogging increases.

  On the other hand, in this embodiment, it is determined whether the air supply amount is excessive, insufficient, or appropriate according to the behavior of the cell voltage, and the air supply amount is corrected based on the determination result. Supply amount. Therefore, when the upper limit voltage control is performed, problems such as unnecessary hydrogen consumption and an increase in the possibility of clogging due to excess generated water do not occur.

  FIG. 8 is a time chart when the current value during idling stop is controlled to be constant. Specifically, the current value is kept constant regardless of the presence or absence of power generation. This is called constant current control.

  If the air flow rate is as designed, the air supply necessary for voltage recovery is supplied by continuing the air supply until timing T3. However, if more air flows than the design due to factors such as individual differences in parts, and supply of the amount of air necessary for voltage recovery is completed at timing T2, air is wasted from timing T2 to timing T3. become. Then, as shown in FIG. 8, when the voltage at which the progress of the high potential deterioration has already become noticeable at the timing T2, the air supply from the timing T2 to the timing T3 progresses the high potential deterioration of the fuel cell stack 1. Just let it. Further, power consumption in the compressor 6 increases due to wasteful air supply.

  On the other hand, in this embodiment, it is determined whether the air supply amount is excessive, insufficient, or appropriate according to the behavior of the cell voltage, and the air supply amount is corrected based on the determination result. Supply amount. Therefore, the progress of the high potential deterioration can be suppressed. Further, an increase in power consumption of the compressor 6 can be prevented.

  In the present embodiment, the air supply amount calculated based on the rotation speed of the compressor 6 or the air supply amount actually measured by the flow meter 31 is corrected to increase or decrease, so that the air supply amount during idle stop is controlled with higher accuracy. be able to.

  Further, since the cell voltage having a strong correlation with the residual oxygen amount in the stack is used for estimating the state in the stack, it can be estimated with high accuracy. Furthermore, since the increase or decrease is adjusted based on the estimation result, the air supply amount can be controlled more appropriately.

(Second Embodiment)
The present embodiment is the same as the first embodiment with respect to the system configuration and the basic control routine, and only the method for determining the excess or deficiency of the air supply amount during idle stop is different. Therefore, this difference will be described.

  FIG. 9 is a flowchart showing a control routine for determining the air supply amount executed by the controller 9 in the present embodiment.

  In step S200, the controller 9 reads the detection value of the voltage sensor 11.

  In step S210, the controller 9 calculates a voltage drop rate ΔCV of the minimum voltage MinCV. The voltage drop speed ΔCV is an absolute value of the speed. That is, the voltage decreases faster as the value of the voltage decrease rate ΔCV is larger.

  In step S220, the controller 9 determines whether or not the voltage drop rate ΔCV is equal to or less than the threshold value Vb. The threshold value Vb is a boundary value indicating whether or not the air supply amount is insufficient. When the voltage drop rate ΔCV is equal to or lower than the threshold value Vb, the process of step S230 is executed. When the voltage drop rate ΔCV is larger than the threshold value Vb, that is, when the air supply amount is insufficient, the process of step S250 is executed.

  In step S230, the controller 9 determines whether or not the voltage drop rate ΔCV is greater than the threshold value Va. The threshold value Va is a boundary value indicating whether or not the air supply amount is excessive. When the voltage drop rate ΔCV is larger than the threshold value Va, the process of step S240 is executed. When the voltage drop rate ΔCV is equal to or less than the threshold value Va, that is, when the air supply amount is excessive, the process of step S260 is executed. .

  Steps S240-S260 are the same as steps S140-S160 in FIG.

  As described above, according to the present embodiment, the air supply amount during idle stop can be appropriately controlled as in the first embodiment.

  Instead of the voltage drop rate ΔCV, the magnitude of the deviation between the average voltage AveCV and the minimum voltage MinCV may be used. In this case, if the deviation is larger than the threshold value for insufficient determination, the supply amount is increased. If the deviation is smaller than the excessive determination threshold value, the supply amount is decreased.

(Third embodiment)
The basic system configuration of this embodiment is the same as that of the first embodiment, but there is a difference that all air supply amounts during idle stop are stored.

  FIG. 10 is a control block diagram showing an overview of air supply control during idle stop by the controller 9 in the present embodiment. As shown in FIG. 10, after the air supply amount is determined by the supply air amount determination unit 23, a supply amount storage unit 40 for storing the air supply amount is provided. In the first embodiment, the air supply amount set by the supply air amount determination unit 23 is only held until the next calculation, but in this embodiment, the supply amount storage unit 40 is at least the previous time and the previous air supply amount. Remember.

  FIG. 11 is a flowchart showing a control routine for determining the air supply amount executed by the controller 9 in the present embodiment.

  In steps S300 and S310, the controller 9 reads the detection value of the voltage sensor 11, and calculates the average voltage AveCV and the minimum voltage MinCV.

  In step S320, the controller 9 determines whether or not the minimum voltage MinCV is equal to or lower than the threshold value Vb. The threshold value Vb is a boundary value indicating whether or not the air supply amount is insufficient. When the minimum voltage MinCV is less than or equal to the threshold value Vb, the process of step S330 is executed if the air supply amount is insufficient, and the process of step S370 is executed if it is greater than the threshold value Vb.

  In step S330, the controller 9 adds 1 to the shortage counter Cdown and sets the excess counter Cup to 0.

  In step S340, the controller 9 determines whether or not the shortage counter Cdown is greater than 1. If larger, the process of step S350 is executed, and if smaller, the process of step S360 is executed.

  In step S350, the controller 9 performs an increase correction on the previous supply amount in the same manner as in step S150 of FIG. This is expressed by the following equation (1). The increment α is a variable value and is set in the same manner as in the first embodiment.

Q (i) = Q (i-1) + α (1)
Q (i): Air supply amount in the i-th air supply, α: Increase amount

  In step S360, the controller 9 increases and corrects the air supply amount in the same manner as in step S350. However, the amount of increase α is set so that the current air supply amount is not less than the previous air supply amount and not more than the previous air supply amount. The process of step S360 is performed when the air supply amount is excessive and the result is that the air supply amount is reduced as a result of correcting the decrease in the air supply amount. That is, the previous air supply amount is insufficient, but the previous air supply amount is excessive. Therefore, as described above, the increased amount α is set so that the air supply amount is not less than the previous time and not more than once before.

  In step S370, the controller 9 determines whether or not the minimum voltage MinCV is larger than the threshold value Va. If larger, the process of step S380 is executed, and if smaller, the process of step S420 is executed.

  In step S380, the controller 9 sets the deficiency counter Cdown to 0 and adds 1 to the excess counter Cup.

  In step S390, the controller 9 determines whether or not the excess counter Cup is larger than 1. If the excess counter Cup is larger, the process of step S400 is performed, and if smaller, the process of step S410 is performed.

  In step S400, the controller 9 performs a decrease correction for the previous supply amount in the same manner as in step S160 of FIG. This is expressed by the following equation (2). The decrease amount β is a variable value and is set in the same manner as in the first embodiment.

Q (i) = Q (i−1) −β (2)
Q (i): Air supply amount in the i-th air supply, β: Weight loss increase

  In step S410, the controller 9 corrects the amount of air supply to be reduced as in step S400. However, the amount of decrease β is set so that the current air supply amount is not less than the previous air supply amount and not more than the previous air supply amount. The process of step S410 is performed when the air supply amount is insufficient and, as a result of increasing the air supply amount, the result is an excessive amount. That is, the previous air supply amount is insufficient, but the previous air supply amount is excessive. Therefore, as described above, the amount of decrease β is set so that the air supply amount is not less than the previous time and not more than the previous time.

  In step S420, the controller 9 maintains the current air supply amount. In step S430, the controller 9 sets both the shortage counter Cdown and the excess counter Cup to 0.

  Thus, in this control routine, when the minimum voltage MinCV is below the threshold value Vb, the increase correction is repeated until it exceeds the threshold value Va. On the other hand, when the minimum voltage MinCV is higher than the threshold value Va, the decrease correction is repeated until it is lower than the threshold value Vb.

  Thereby, the air supply amount approaches an appropriate value every time the air supply during idle stop is repeated.

  The air supply amount set by this control routine is stored in the nonvolatile storage unit 40a of the supply amount storage unit 40. That is, the air supply amount corrected by the increase / decrease amount by the present control routine is stored even after the current vehicle operation ends. The stored air supply amount is used at the next vehicle operation. Thereby, at the time of the next vehicle operation, the air supply amount that has approached an appropriate value in the current vehicle operation can be used from the beginning.

  In the present embodiment, the calculation result determination unit 22 determines whether the amount of filling due to air supply during idle stop is excessive, insufficient, or appropriate. However, the amount of filling due to air supply during idle stop is excessive. It may be determined only whether or not the amount of filling due to air supply during idle stop is insufficient.

  The present invention is not limited to the above-described embodiments, and it goes without saying that various modifications can be made within the scope of the technical idea described in the claims.

DESCRIPTION OF SYMBOLS 1 Fuel cell stack 2 Anode 3 Cathode 4 Electrolyte membrane 5 Hydrogen tank 6 Compressor 7 Hydrogen supply path 8 Air supply path 9 Controller 10 Rotational speed sensor 21 Cell voltage calculation part 22 Calculation result judgment part 23 Supply air quantity determination part 24 Air supply quantity Arithmetic unit 31 Flow meter 40 Supply amount storage unit

Claims (14)

A voltage detector for detecting a cell voltage or a cell group voltage;
A cell voltage calculation unit for calculating a voltage state based on a detection result of the voltage detection unit;
Based on the calculation result of the cell voltage calculation unit, a calculation result determination unit that determines whether the previous value of the air supply amount intermittently supplied to the cathode during idle stop is excessive or insufficient,
A supply air amount determination unit that determines to decrease or increase the air supply amount with respect to a preset fixed value or a previous supply amount according to a determination result of the calculation result determination unit;
A fuel cell system comprising:   The fuel cell system according to claim 1, further comprising an air supply amount calculation unit that calculates the previous supply amount by calculation.   The fuel cell system according to claim 1, further comprising a flow meter that directly measures the previous supply amount. The cell voltage calculation unit calculates a determination value that changes according to voltage fluctuations during air supply stop,
The calculation result determination unit determines whether the fixed value or the previous supply amount is excessive, insufficient, or appropriate by comparing a predetermined threshold value with the determination value.
The fuel cell according to any one of claims 1 to 3, wherein the supply air amount determination unit determines to increase the air supply amount with respect to the fixed value or the previous supply amount when it is determined that the supply air amount is insufficient. system. The cell voltage calculation unit calculates a determination value that changes according to voltage fluctuations during air supply stop,
The calculation result determination unit determines whether the fixed value or the previous supply amount is excessive, insufficient, or appropriate by comparing a predetermined threshold value with the determination value.
The fuel cell according to any one of claims 1 to 4, wherein the supply air amount determination unit determines to reduce the air supply amount with respect to the fixed value or the previous supply amount when it is determined that the supply air amount is excessive. system.   6. The fuel cell system according to claim 1, wherein the supply air amount determination unit changes an increase amount or a decrease amount with respect to the fixed value or the previous supply amount according to a determination result of the calculation result determination unit. .   The said supply air amount determination part increases an increase part, so that the difference with the said threshold value and the said determination value is large, when increasing the said air supply amount with respect to the said fixed value or the said last supply amount. The fuel cell system described in 1.   The fuel cell system according to any one of claims 1 to 7, further comprising: a storage unit that stores at least the previous supply amount and the previous supply amount of air supply performed during idle stop.   The fuel cell system according to claim 8, wherein the supply air amount determination unit repeats increasing the air supply amount until the determination result is excessive or appropriate when the calculation result determination unit determines that the calculation result determination unit is insufficient.   The supply air determination unit reduces the air supply amount with respect to the previous supply amount when the determination result turns from insufficient to excessive, but sets the air supply amount after the reduction more than the previous supply amount. The fuel cell system described.   11. The fuel cell system according to claim 8, wherein when the calculation result determination unit determines that the calculation result determination unit is excessive, the supply air amount determination unit repeatedly reduces the air supply amount until the determination result is insufficient or appropriate.   The supply air amount determination unit increases the air supply amount with respect to the previous supply amount when the determination result changes from being excessive to insufficient, but sets the air supply amount after the increase to be less than the previous supply amount. The fuel cell system described in 1.   The storage unit includes a nonvolatile storage unit, stores an air supply amount in the nonvolatile storage unit, and the supply air determination unit uses the air supply amount stored in the nonvolatile storage unit during the next operation. 12. The fuel cell system according to any one of 12 above.   The supply air amount determination unit determines the air supply amount during the first idle stop at the time of the first operation after the system manufacture, and the volume of the air flow path facing the active area that generates power of the cell stack constituting the fuel cell. The fuel cell system according to any one of claims 1 to 13, wherein the fuel cell system is larger than an active area volume that is a sum of pore volumes of gas diffusion layers in the active area.

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