JP2012059557A - Fuel cell system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To discharge water collected in a fuel cell with appropriate timing while power generation is stopped.SOLUTION: While a fuel cell 1 is stopped, a control unit 50 estimates, by using a temperature difference between a temperature detected by a temperature sensor 63 when the fuel cell 1 is stopped and a current temperature detected by the temperature sensor 63, a present condensed water quantity in the fuel cell 1 based on a preliminarily created condensed water map showing the relationship between the temperature difference and the condensed water quantity in the fuel cell 1; estimates, by using a pressure difference between an anode pressure detected by a pressure sensor 62 when the fuel cell 1 is stopped and a current anode pressure detected by the pressure sensor 62, a quantity of water generated in the fuel cell 1 after the fuel cell 1 is stopped based on a preliminarily created generated water map showing the relationship between the pressure difference and the quantity of water generated in the fuel cell 1; and if the sum of the current condensed water quantity and the generated water quantity after the fuel cell 1 is stopped exceeds a prescribed water quantity which affects stable startup of the fuel cell 1, executes anode scavenging by scavenging means.

Description

  The present invention relates to a fuel cell system.

  In a fuel cell having a solid polymer electrolyte membrane and generating power by supplying fuel to the anode electrode and supplying an oxidant to the cathode electrode, if the water in the fuel cell becomes excessive while the fuel cell is stopped, the electrode Water accumulates on the top and power generation stability at the next start-up deteriorates.

Therefore, so-called scavenging is performed in which scavenging gas is supplied to the gas flow path in the fuel cell and the fluid in the flow path is discharged so as not to deteriorate the power generation stability at the time of startup.
For example, in Patent Document 1, when a fuel cell is stopped, it is detected whether or not the amount of water in the fuel cell is large based on the temperature of the fuel cell, the generated current, and the generated voltage immediately before the stop. A fuel cell system is described in which only the cathode electrode side is scavenged with scavenging gas when there are many, and the cathode electrode side and anode electrode side are separately scavenged with scavenging gas when the amount of moisture is low. Yes.

Patent Document 2 discloses a fuel cell system that discharges (scavenges) water remaining in a fuel cell by boosting and depressurizing the gas flow path of the fuel cell with a scavenging gas. Predict the amount of water remaining in the battery, determine whether or not residual water removal is necessary based on the prediction result of the residual water amount, and determine the number of times of pressure increase / decrease based on the prediction result of the residual water amount A fuel cell system is described.
In the fuel cell systems disclosed in these patent documents, the scavenging process is performed immediately after the ignition switch is turned off, that is, immediately after the fuel cell is stopped.

JP 2007-123040 A JP 2008-10347 A

By the way, when scavenging with scavenging gas immediately after stopping the fuel cell as in the past, the time from the stop to the next activation is short, and as a result, scavenging is performed even when there is no need for scavenging. There will be wasted energy. In particular, if the anode electrode is scavenged with scavenging gas, there will be no fuel in the gas flow path connected to the anode electrode. Need to be replaced. When this is performed when the time from stop to start is short and consequently scavenging is not necessary, fuel is wasted.
Therefore, recently, scavenging is not performed immediately after the fuel cell is stopped, but is performed after a predetermined time has elapsed since the fuel cell was stopped.

  In this case, since the scavenging is performed when a predetermined time has elapsed since the fuel cell was stopped regardless of the state of the fuel cell, the fuel is stored in a state where water is accumulated in the fuel cell before the scavenging is performed. A situation where the battery is activated may also occur. In such a situation, there is a problem that the power generation stability at the time of startup deteriorates. Moreover, since power generation is continued in a state where power generation stability is deteriorated, there is a problem that the deterioration of the solid polymer electrolyte membrane is advanced.

  Note that the method for detecting the amount of water in the fuel cell disclosed in Patent Document 1 is based on the power generation current and power generation voltage of the fuel cell immediately before the stop, and determines whether the amount of water at the time of stop is large or small. However, the water content in the fuel cell is not quantitatively estimated.

  Further, the method for predicting the amount of water remaining in the fuel cell disclosed in Patent Document 2 is such that an oxidant gas is caused to flow through the gas flow path of the fuel cell during stoppage, and the fuel cell inlet and outlet generated at that time The residual moisture content is estimated based on the differential pressure. Since this method starts the compressor and uses energy to flow the oxidant gas every time it is estimated, there is no problem in estimating only once immediately after the power generation is stopped as described in Patent Document 2. However, it is not suitable when the residual moisture amount is estimated multiple times while the fuel cell is stopped.

  Therefore, the present invention provides a fuel cell system that can improve the power generation stability by discharging water accumulated in the fuel cell at an appropriate timing during power generation stoppage.

The fuel cell system according to the present invention employs the following means in order to solve the above problems.
The invention according to claim 1 is a fuel cell (for example, a fuel cell 1 in an embodiment described later) that supplies power to the anode electrode and supplies an oxidant to the cathode electrode, and detects the temperature of the fuel cell. A temperature sensor (for example, a temperature sensor 63 in an embodiment to be described later), and a fuel gas channel (for example, a fuel supply channel 16a and an anode off-gas channel 21 in an embodiment to be described later) connected to the anode electrode of the fuel cell. , An anode scavenging flow path 23, a scavenging discharge flow path 30), a pressure sensor for detecting the pressure of the fuel (for example, a pressure sensor 62 in an embodiment described later), and a fluid in the fuel system gas flow path for discharging gas Scavenging means (for example, a compressor 7, a scavenging introduction valve 22, and a scavenging discharge valve 29 in an embodiment to be described later) and a control unit (for controlling the scavenging means) For example, the control unit 50) in a later-described embodiment includes a temperature detected by the temperature sensor when the fuel cell is stopped and the temperature. When the temperature difference from the current temperature detected by the sensor is used for the relationship between the temperature difference determined in advance and the amount of condensed water in the fuel cell, the current amount of condensed water in the fuel cell is estimated and stopped. Stopping in the fuel cell by using the pressure difference between the pressure detected by the pressure sensor and the current pressure detected by the pressure sensor as a relationship between the pressure difference determined in advance and the amount of water generated in the fuel cell. Estimating the amount of post-generated water, and performing discharge by the scavenging means when the sum of the current amount of condensed water and the amount of generated water after stopping exceeds a predetermined amount of water that affects the stable start-up of the fuel cell. Characteristic system It is.

  The invention according to claim 2 is the invention according to claim 1, wherein the control unit stores a history of pressure detected by the pressure sensor after the fuel cell is stopped, and is detected by the pressure sensor. When the current pressure is lower than the previous pressure, correction is performed so that the amount of generated water after the stop increases as the current temperature detected by the temperature sensor increases.

According to the first aspect of the present invention, the sum of the amount of condensed water estimated to have occurred in the fuel cell between the time when the fuel cell is stopped and the present time and the amount of generated water after the stop affect the stable start of the fuel cell. When the specified amount of water is exceeded, scavenging is performed to flow the exhaust gas through the fuel system gas flow path connected to the anode electrode and discharge the water accumulated on the anode electrode side. Can be started. As a result, deterioration of the solid polymer electrolyte membrane of the fuel cell can be suppressed.
In addition, since it is only necessary to activate a temperature sensor that detects the temperature of the fuel cell and a pressure sensor that detects the pressure in the fuel system gas flow path to determine whether or not to perform scavenging. Energy can be kept extremely small.
According to the second aspect of the present invention, the higher the temperature, the more the reaction between the fuel and the oxidant is promoted, so that it is possible to correct the increase in the amount of generated water after the stop. Accuracy is improved.

It is a schematic block diagram in the Example of the fuel cell system concerning this invention. It is a schematic diagram for demonstrating the scavenging timing determination procedure. It is a flowchart which shows the system stop control in an Example. It is a condensed water map used in an Example. It is a production | generation water map used in an Example.

Embodiments of a fuel cell system according to the present invention will be described below with reference to the drawings of FIGS.
FIG. 1 is a schematic configuration diagram of a fuel cell system in an embodiment, and this fuel cell system is mounted on a fuel cell vehicle.
The fuel cell 1 is configured by laminating a plurality of cells formed by sandwiching a solid polymer electrolyte membrane made of, for example, a solid polymer ion exchange membrane from both sides between an anode electrode and a cathode electrode. When hydrogen is supplied as (fuel) and oxygen-containing air is supplied as the oxidant gas (oxidant) to the cathode electrode, hydrogen ions generated by the catalytic reaction at the anode electrode pass through the solid polymer electrolyte membrane to the cathode. It moves to the pole and generates electricity by causing an electrochemical reaction with oxygen at the cathode pole to produce water. Part of the generated water generated on the cathode electrode side permeates the solid polymer electrolyte membrane and back diffuses to the anode electrode side, so that the generated water also exists on the anode electrode side.

The air is pressurized to a predetermined pressure by a compressor 7 such as a supercharger, introduced into the oxidant flow passage 6 in the fuel cell 1 through the air supply flow path 8, and supplied to the cathode electrode of each cell. After the air supplied to the fuel cell 1 is used for power generation, it is discharged from the fuel cell 1 to the air discharge passage 9 together with the generated water on the cathode electrode side, and is discharged to the dilution box 11 via the pressure control valve 10. .
The air supply flow path 8 is provided with a cathode inlet pressure sensor 61 that detects the pressure of air supplied to the oxidant flow passage 6 of the fuel cell 1. The cathode inlet pressure sensor 61 outputs an electrical signal corresponding to the detected pressure value to the control device (control unit) 50. Note that the pressure detected by the cathode inlet pressure sensor 61 is substantially equal to the pressure of air in the oxidant flow passage 6.

On the other hand, the hydrogen supplied from the hydrogen tank 15 is introduced into the fuel flow passage 5 in the fuel cell 1 through the fuel supply passage 16 and supplied to the anode electrode of each cell. A gas supply valve 17, a shut-off valve 18, a regulator 19, and an ejector 20 are provided in the fuel supply flow path 16 in order from the upstream side, and the hydrogen supplied from the hydrogen tank 15 is reduced to a predetermined pressure by the regulator 19. To the fuel flow passage 5 of the fuel cell 1. Unreacted hydrogen that has not been consumed is discharged from the fuel cell 1 as an anode off-gas, sucked into the ejector 20 through the anode off-gas passage 21, and merged with fresh hydrogen supplied from the hydrogen tank 15 again. It is supplied to the fuel flow path 5 of the fuel cell 1. That is, the anode offgas discharged from the fuel cell 1 circulates in the fuel cell 1 through the anode offgas passage 21 and the fuel supply passage 16a downstream of the ejector 20.
The fuel supply passage 16a and the air supply passage 8 downstream of the ejector 20 are connected by an anode scavenging passage 23 having a scavenging introduction valve 22, and the fuel supply passage 16a is connected via the anode scavenging passage 23. It is possible to introduce air into.
An anode inlet pressure sensor 62 that detects the pressure of hydrogen supplied to the fuel flow passage 5 of the fuel cell 1 is provided in the fuel supply flow passage 16a downstream of the junction with the anode scavenging flow passage 23. Yes. The anode inlet pressure sensor 62 outputs an electrical signal corresponding to the detected pressure value to the control device 50. Note that the pressure detected by the anode inlet pressure sensor 62 is substantially equal to the hydrogen pressure in the fuel flow passage 5.

  The anode off-gas flow path 21 is provided with a catch tank 24 that collects condensed water contained in the anode off-gas, and the ejector 20 is supplied with hydrogen from which condensed water has been removed. The catch tank 24 is connected to the dilution box 11 via a drainage flow path 26 provided with a drainage valve 25. When a predetermined amount of water accumulates in the catch tank 24, the drainage valve 25 opens, and the accumulated water is anode offgas. And is discharged into the dilution box 11 together with the anode off gas.

A purge flow path 28 having a purge valve 27 and a scavenging discharge flow path 30 having a scavenging discharge valve 29 are branched from the anode off-gas flow path 21 downstream of the catch tank 24. The scavenging / discharge passage 30 is connected to the dilution box 11.
The purge valve 27 is normally closed during power generation of the fuel cell 1 and opens when a predetermined condition is satisfied, and discharges impurities contained in the anode off gas to the dilution box 11 together with the anode off gas.
The scavenging discharge valve 29 is normally closed, and is opened when scavenging the anode side while the fuel cell system is stopped, and discharges the scavenging gas to the dilution box 11. The scavenging will be described in detail later.

A dilution gas flow path 31 branched from the air supply flow path 8 is connected to the dilution box 11. The on-off valve 32 provided in the dilution gas channel 31 is opened when supplying the dilution gas (air) to the dilution box 11 without passing through the fuel cell 1.
Then, the anode off-gas discharged to the dilution box 11 via the drainage flow path 26, the purge flow path 28, and the scavenging discharge flow path 30 flows into the dilution box 11 via the air discharge flow path 9 or the dilution gas flow path 31. The diluted gas is discharged from the dilution box 11 through the exhaust pipe 33 to the atmosphere.
Further, the fuel cell 1 is provided with a temperature sensor 63 that detects the temperature in the fuel cell 1, and the temperature sensor 63 outputs an electrical signal corresponding to the detected temperature value to the control device 50.

  The control device 50 controls the start / stop of the fuel cell system based on the on / off signal input from the ignition switch 51, and the compressor 7 and the pressure control valve 10 according to the control contents such as output control of the fuel cell 1. The gas supply valve 17, the shutoff valve 18, the scavenging introduction valve 22, the drain valve 25, the purge valve 27, the scavenging discharge valve 29, the on-off valve 32, and the like are controlled. In FIG. 1, these control signal lines are omitted.

  The control device 50 is connected to a timer 52 for starting the control device 50 at a predetermined interval while the control device 50 is stopped, so that the fuel cell system is stopped (that is, the control device 50 is stopped). ), When the time set in the timer 52 elapses, the control device 50 is started. Hereinafter, the control for starting the stopped control device 50 at a predetermined interval is referred to as RTC (Real Time Clock) control. Since RTC control can suppress power consumption, it has an effect of improving fuel consumption.

  In this fuel cell system, air (into the fuel cell 1 and the gas flow path at a predetermined timing so that the power generation stability does not deteriorate at the next start-up due to water accumulated in the fuel cell 1 while the fuel cell 1 is stopped. Scavenging to discharge water by flowing the gas for discharge. In order to determine the timing of this scavenging, the amount of water accumulated on the anode side in the fuel cell 1 (hereinafter referred to as residual water) is estimated. The estimation of the residual water amount is not always performed while the fuel cell system is stopped, but is performed when the control device 50 is activated by RTC control. The control device 50 performs a scavenging process when the estimated residual water amount is equal to or greater than a predetermined value, and stops the control device 50 again and waits for the next interval when it is less than the predetermined value.

Here, the residual water accumulated on the anode electrode side when the fuel cell 1 is stopped will be described with reference to the drawing of FIG.
There are two possible causes for the generation of water in the gas flow path on the anode electrode side when the fuel cell 1 is stopped.

(1) When the reaction gas remains in the fuel cell 1 and each reaction gas channel is sealed and stopped, the water vapor existing in the gas channel is condensed as the temperature in the fuel cell 1 decreases. Condensate is generated. The amount of condensed water generated is related to the amount of temperature decrease of the fuel cell 1 from when the fuel cell 1 is stopped to the present when the humidity in the fuel cell 1 is controlled to be substantially constant. The amount of condensed water increases.

(2) Sealing each reaction gas flow path of the fuel cell 1 while keeping hydrogen at a pressure higher than atmospheric pressure on the anode side in the fuel cell 1 and air at atmospheric pressure remaining on the cathode side When stopped, oxygen on the cathode side permeates the solid polymer electrolyte membrane of the fuel cell 1 to the anode side (hereinafter referred to as oxygen cross-leakage), so that hydrogen and oxygen react on the anode side and the anode side Generated water is generated. The amount of generated water is related to the amount of hydrogen consumed in the reaction, and as the amount of consumed hydrogen increases, the gas pressure on the anode electrode side (hereinafter referred to as anode pressure) decreases. Therefore, the amount of generated water increases as the amount of decrease in anode pressure increases. However, when the anode pressure is balanced with the pressure on the cathode electrode side and becomes almost atmospheric pressure, the oxygen cross-leak stops and the reaction between hydrogen and oxygen does not occur, so the amount of generated water does not increase any more. Further, the amount of generated water is related to the temperature in the fuel cell 1, and the reaction becomes more active as the temperature in the fuel cell 1 is higher, so the amount of generated water also increases.

  Therefore, in the fuel cell system of this embodiment, the amount of condensed water Q1 generated on the anode electrode side is estimated based on the temperature drop amount ΔT of the fuel cell 1 when the fuel cell 1 is stopped, and the anode when the fuel cell 1 is stopped Based on the pressure drop amount ΔP, the amount of generated water Q2 generated on the anode electrode side is estimated, and when the estimated amount of condensed water Q1 and the amount of generated water Q2 exceeds a predetermined value, the gas flow path connected to the anode electrode Anode scavenging is performed in which air (exhaust gas) is flowed through to discharge water accumulated on the anode side. Here, if the predetermined value is set to the amount of water that adversely affects the stable start-up of the fuel cell 1, the anode immediately after the amount of water accumulated on the anode electrode side exceeds the amount of water that adversely affects the stable start-up of the fuel cell 1. Since scavenging can be performed, the fuel cell 1 can be stably started at the next startup.

Hereinafter, scavenging control while the fuel cell system is stopped will be described with reference to FIG.
FIG. 3 is a flowchart showing stop control of the fuel cell system.
First, in step S101, it is determined whether or not the ignition switch 51 is turned off.
If the determination result in step S101 is “NO”, the fuel cell 1 is in the power generation operation, and thus the execution of this routine is terminated.
When the determination result in step S101 is “YES”, the process proceeds to step S102, the supply of the reaction gas (hydrogen and air) to the fuel cell 1 is stopped, and the temperature detected by the temperature sensor 62 immediately thereafter. T0 and the pressure P0 detected by the anode pressure sensor 62 are stored in a storage unit (not shown) of the control device 50. That is, the temperature T0 and anode pressure P0 of the fuel cell 1 when the fuel cell system is stopped are stored. The supply of the reactive gas to the fuel cell 1 is stopped by stopping the compressor 7 and closing the gas supply valve 17, the shutoff valve 18, the drain valve 25, the purge valve 27, and the scavenging discharge valve 29.
Next, it progresses to step S103 and the control apparatus (ECU) 50 is stopped.

Next, the process proceeds to step S104, and after the control device 50 is stopped, it is determined whether or not the control device 50 has been started after the time set in the timer 52 (that is, the monitoring interval) has elapsed. In other words, it is determined whether or not the control device 50 is activated by RTC control.
If the determination result in step S104 is “NO”, the process returns to step S104. That is, the determination in step S104 is repeated until the monitoring interval elapses.

When the determination result in step S104 is “YES”, the process proceeds to step S105, and the amount of condensed water Q1 generated on the anode electrode side of the fuel cell 1 due to the temperature drop of the fuel cell 1 from the stop of the fuel cell 1 to the present time. Is estimated.
More specifically, the control device 50 detects the current temperature T1 of the fuel cell 1 with the temperature sensor 63, and calculates the temperature decrease amount ΔT by subtracting the temperature T0 when the fuel cell is stopped from the current temperature T1. When the temperature decrease amount ΔT becomes a negative value, the temperature decrease amount ΔT is set to zero. Then, referring to the condensed water map shown in FIG. 4, a condensed water amount Q1 corresponding to the calculated temperature decrease amount ΔT is obtained.
The condensed water map shown in FIG. 4 is an experiment in advance on a fuel cell equivalent to the fuel cell 1 used in this fuel cell system by controlling the humidity in the fuel cell 1 to a predetermined humidity. The relationship between the temperature drop amount ΔT during the stop of the fuel cell and the amount of condensed water Q1 generated on the anode electrode side is acquired as data, and is mapped based on the acquired data. In the condensed water map of this embodiment, the condensed water amount Q1 increases as the temperature decrease amount ΔT increases.

Next, the process proceeds to step S106, and the amount of generated water Q2 generated by the reaction of hydrogen and oxygen on the anode electrode side of the fuel cell 1 from the time when the fuel cell 1 is stopped to the present time is estimated.
More specifically, the control device 50 detects the current anode pressure P1 of the fuel cell 1 by the pressure sensor 62, and subtracts the current anode pressure P1 from the anode pressure P0 when the fuel cell is stopped to obtain the anode pressure decrease amount ΔP. calculate. When the anode pressure drop amount ΔP becomes a negative value, the anode pressure drop amount ΔP is set to zero. Further, the control device 50 stores the detected current anode pressure P1, and stores the history of the anode pressure since the fuel cell 1 was stopped. Then, referring to a map corresponding to the current temperature T1 of the fuel cell 1 from the generated water map shown in FIG. 5, a generated water amount Q2 corresponding to the calculated anode pressure drop amount ΔP is obtained.

  The generated water map shown in FIG. 5 shows that the fuel cell equivalent to the fuel cell 1 used in this fuel cell system is tested in advance for each temperature of the fuel cell, and the anode pressure is lowered while the fuel cell is stopped. The relationship between the amount ΔP and the amount of generated water Q2 generated on the anode electrode side is acquired as data, and is mapped based on the acquired data. In the generated water map of this embodiment, while the current anode pressure P1 is lower than the lowest anode pressure after stopping the fuel cell (before the peak), the generated water amount Q2 increases as the anode pressure decrease ΔP increases. In comparison with the case of the same anode pressure drop amount ΔP, the generated water amount Q2 increases as the temperature of the fuel cell increases. In other words, when the current anode pressure is lower than the current anode pressure, it can be said that the amount of generated water Q2 is corrected so as to increase as the current temperature increases. Since the generated water amount Q2 is calculated by correcting the temperature in this way, the estimation accuracy of the generated water amount is improved. In addition, after the current anode pressure P1 reaches the minimum pressure (after the peak), the generated water amount Q2 is constant.

Next, the process proceeds to step S107, and the total water amount Q accumulated on the anode electrode side is calculated by adding the condensed water amount Q1 estimated in step S105 and the generated water amount Q2 estimated in step S106 (Q = Q1 + Q2). It is determined whether or not the total water amount Q exceeds a predetermined value set in advance. Here, the predetermined value is an amount of water that adversely affects the stable start-up of the fuel cell 1, and is obtained in advance by experiments.
When the determination result in step S107 is “NO” (Q ≦ predetermined value), the process returns to step S103, the control device 50 is stopped, and the RTC control is restarted.
If the determination result in step S107 is “YES” (Q> predetermined value), the process proceeds to step S108, the scavenging of the fuel cell 1 is performed, and the execution of this routine is terminated.

In this embodiment, scavenging first scavenges the cathode side of the fuel cell 1 (hereinafter referred to as “cathode scavenging”), and then performs scavenging on the anode side (hereinafter referred to as “anode scavenging”). Cathodic scavenging is performed by driving the compressor 7, opening the pressure control valve 10, and allowing air to flow through the air supply flow path 8, the oxidant flow path 6 in the fuel cell 1, and the air discharge flow path 9. The anode scavenging drives the compressor 7, closes the shut-off valve 18, opens the scavenging introduction valve 22 and the scavenging discharge valve 29, and supplies air to the fuel downstream of the air supply channel 8, anode scavenging channel 23, and ejector 20. The flow is performed through the supply flow channel 16 a, the fuel flow channel 5 in the fuel cell 1, the anode offgas flow channel 21, and the scavenging discharge flow channel 30.
In this embodiment, the cathode scavenging and the anode scavenging are performed. However, the cathode scavenging may not be performed, and only the anode scavenging may be performed.

In this embodiment, the compressor 7, the scavenging introduction valve 22, and the scavenging discharge valve 29 constitute scavenging means on the anode electrode side that supplies air (exhaust gas) and discharges the fluid in the fuel system gas flow path, The fuel supply flow path 16a, the anode off-gas flow path 21, the anode scavenging flow path 23, and the scavenging discharge flow path 30 downstream from the ejector 20 constitute a fuel system gas flow path.
Further, the compressor 7 and the pressure control valve 10 constitute a scavenging means on the cathode electrode side for supplying air (discharge gas) and discharging the fluid in the oxidant-based gas flow path, and the air supply flow path 8 and the air The discharge passage 9 constitutes an oxidant gas passage.

According to this fuel cell system, when the estimated amount of condensed water Q1 and generated water amount Q2 exceeds a predetermined value that adversely affects the stable start-up of the fuel cell 1, air ( Since the anode scavenging is performed to flow the discharge gas) and discharge the water accumulated on the anode electrode side, the fuel cell 1 can be stably started at the next startup. As a result, deterioration of the solid polymer electrolyte membrane of the fuel cell 1 can be suppressed.
Further, since it is only necessary to activate the temperature sensor 63 that detects the temperature of the fuel cell 1 and the pressure sensor 62 that detects the anode pressure to determine whether or not to perform anode scavenging, the energy consumption at the time of determination is reduced. It can be kept very small.

[Other Examples]
The present invention is not limited to the embodiment described above.
For example, in the embodiment described above, the generated water map shown in FIG. 5 is prepared in advance for each temperature of the fuel cell, and the map corresponding to the current temperature T1 of the fuel cell 1 is used in accordance with the anode pressure decrease amount ΔP. The generated water amount Q2 is obtained. For example, only the generated water map of the reference fuel cell temperature (for example, 20 ° C.) is provided, and the generated water amount Q2 corresponding to the anode pressure drop amount ΔP is obtained from this generated water map, You may perform the temperature correction of the production | generation water amount Q2 by multiplying the correction coefficient according to temperature.

1 Fuel cell 7 Compressor (scavenging means)
16a Fuel supply channel (fuel system gas channel)
21 Anode off-gas channel (fuel gas channel)
22 Scavenging introduction valve (scavenging means)
23 Anode scavenging flow path (fuel gas flow path)
29 Scavenging exhaust valve (scavenging means)
30 Scavenging exhaust passage (fuel system gas passage)
50 Control device (control unit)
62 Pressure sensor 63 Temperature sensor

Claims (2)

A fuel cell in which fuel is supplied to the anode electrode and oxidant is supplied to the cathode electrode to generate electricity;
A temperature sensor for detecting the temperature of the fuel cell;
A pressure sensor for detecting the pressure of the fuel in the fuel system gas flow path connected to the anode electrode of the fuel cell;
Scavenging means for supplying a discharge gas to discharge the fluid in the fuel system gas flow path;
A control unit for controlling the scavenging means;
A fuel cell system comprising:
While the fuel cell is stopped, the control unit calculates a temperature difference between the temperature detected by the temperature sensor and the current temperature detected by the temperature sensor when the fuel cell is stopped, Estimate the current amount of condensed water in the fuel cell using the relationship with the amount of condensed water in the battery, and the pressure detected by the pressure sensor when stopped and the current pressure detected by the pressure sensor The difference is used for the relationship between the pressure difference obtained in advance and the amount of generated water in the fuel cell to estimate the amount of generated water after stop in the fuel cell, and the sum of the current amount of condensed water and the amount of generated water after stop is The system is characterized in that discharge by the scavenging means is performed when a predetermined amount of water that affects stable start-up of the fuel cell is exceeded.   The control unit stores a history of pressure detected by the pressure sensor after the fuel cell is stopped, and when the current pressure detected by the pressure sensor is lower than the previous pressure, the temperature 2. The fuel cell system according to claim 1, wherein correction is performed such that the amount of generated water after the stop increases as the current temperature detected by the sensor increases.

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