JP5144152B2 - Discharge system - Google Patents

Description

  The present invention relates to a discharge system for discharging a fuel cell stack after power generation is stopped.

  In recent years, a polymer electrolyte fuel cell (PEFC) that generates electricity by generating an electrochemical reaction by supplying hydrogen (fuel gas) to the anode and oxygen (oxidant gas) to the cathode, etc. The development of fuel cells is thriving. Fuel cells are being applied in a wide range, such as fuel cell vehicles that run on the power generated by them, and household power supplies.

  However, in such a fuel cell, when hydrogen and air are present on both sides of the MEA (Membrane Electrode Assembly) after the power generation is stopped, in each single cell, OCV (Open Circuit Voltage) Will occur. Then, based on this OCV, a current flows in each single cell, and if the current flows in this way, the single cell may be deteriorated.

  Therefore, in order to prevent the occurrence of such OCV, a technique has been proposed in which the fuel cell stack is discharged after hydrogen generation is stopped, hydrogen and air remaining in the interior are consumed, and OCV is reduced (Patent Document 1). reference).

JP 2004-165028 A

  However, simply by discharging the fuel cell stack after stopping the power generation of the fuel cell stack, hydrogen and air in the fuel cell stack cannot be completely consumed, and the OCV sometimes rises again after the discharge. .

  Then, this invention makes it a subject to provide the discharge system which can discharge a fuel cell stack suitably after a power generation stop.

  As means for solving the above-mentioned problem, the present invention reduces the voltage generated by the reaction gas remaining in the fuel cell stack after the power generation of the fuel cell stack in which a plurality of single cells are connected in series is stopped. A discharge means for discharging the fuel cell stack; a discharge amount calculating means for calculating a subsequent discharge amount at a predetermined timing after the power generation of the fuel cell stack is stopped; the calculated discharge power amount; Discharge execution determining means for determining whether or not to perform discharge based on a predetermined discharge amount serving as a reference for starting discharge, and when the discharge execution determining means determines to execute discharge, discharge is started. And a start control means for controlling the discharge means.

  According to such a discharge system, after the power generation of the fuel cell stack is stopped, the discharge amount calculation means calculates the subsequent discharge amount repeatedly at a predetermined timing. Then, the discharge execution determination means determines whether or not to execute discharge based on the calculated discharge amount and a predetermined discharge amount (0 in the embodiment described later). Next, when the discharge execution determination unit determines to execute the discharge, the start control unit controls the discharge unit so as to start the discharge, so that the fuel cell stack is discharged and the remaining reaction gas is consumed. The voltage of the single cell decreases.

  That is, even if the OCV (the voltage of the entire stack, the voltage of a single cell) rises again after the fuel cell stack is discharged, the discharge amount calculation means continuously performs the subsequent discharge amount at a predetermined timing after the power generation is stopped. Is calculated, discharge is determined based on the amount of discharge, and discharge is started based on the determination result, so that the fuel cell stack can be suitably discharged.

  In the discharge system, it is preferable that the discharge amount calculation unit corrects the subsequent discharge amount based on at least one of an elapsed time after the power generation stop of the fuel cell stack and the number of discharges.

  According to such a discharge system, the discharge amount calculating means corrects the subsequent discharge amount based on at least one of the elapsed time after the power generation stop of the fuel cell stack and the number of discharges. It can be calculated appropriately. In addition, when the elapsed time after the power generation stop of a fuel cell stack becomes long, when the frequency | count of discharge increases, it is preferable to correct | amend so that the subsequent discharge amount may become small.

  In the discharge system, it is preferable that the discharge amount calculation unit corrects the subsequent discharge amount based on at least one of temperature and humidity of the fuel cell stack.

  According to such a discharge system, since the discharge amount calculation means corrects the subsequent discharge amount based on at least one of the temperature and the humidity of the fuel cell stack, the subsequent discharge amount can be appropriately calculated. . In addition, when at least one of the temperature and humidity of the fuel cell stack increases, it is preferable to correct so that the subsequent discharge amount increases.

  In the discharge system, during execution of discharge by the discharge means, voltage determination means for determining whether a current voltage of the single cell or a predetermined number of single cells is equal to or lower than a predetermined voltage, and the current voltage When the voltage is equal to or lower than the predetermined voltage, it is preferable to include stop control means for controlling the discharge means so as to stop discharge.

  According to such a discharge system, during the discharge of the fuel cell stack by the discharge means, whether the current voltage of the single cell or the predetermined number of single cells is equal to or lower than the predetermined voltage at which the discharge should be stopped. Determine whether or not. When the current voltage is equal to or lower than the predetermined voltage, the stop control unit controls the discharge unit to stop the discharge, so that the discharge of the fuel cell stack is stopped. This can prevent the fuel cell stack from being overdischarged.

  According to the present invention, it is possible to provide a discharge system capable of suitably discharging the fuel cell stack after power generation is stopped.

  Hereinafter, an embodiment of the present invention will be described with reference to FIGS.

≪Configuration of fuel cell system≫
A fuel cell system 1 shown in FIG. 1 incorporates a discharge system according to the present invention and is mounted on a fuel cell vehicle (moving body) (not shown).
The fuel cell system 1 includes a fuel cell stack 10, a cell voltage monitor 13, an anode system that supplies and discharges hydrogen (fuel gas and reactive gas) to and from the anode of the fuel cell stack 10, and a cathode of the fuel cell stack 10. A cathode system that supplies and discharges oxygen-containing air (oxidant gas, reactive gas), a scavenging system that guides scavenging gas (non-humidified air) from the cathode system to the anode system when scavenging the fuel cell stack 10, and fuel A power consumption system that consumes the generated power of the battery stack 10, a discharge circuit (discharge means) that discharges the fuel cell stack 10 after power generation is stopped, an IG 71 (ignition), and an ECU 80 (Electronic) that electronically controls these Control Unit, electronic control device).

<Fuel cell stack>
The fuel cell stack 10 is a stack formed by stacking a plurality of (for example, 200 to 400) solid polymer type single cells, and the plurality of single cells are electrically connected in series. The single cell includes an MEA and two conductive separators sandwiching the MEA. The MEA includes an electrolyte membrane (solid polymer membrane) made of a monovalent cation exchange membrane or the like, and an anode and a cathode sandwiching the electrolyte membrane.

  The anode and cathode are mainly composed of a conductive porous material such as carbon paper, and contain a catalyst (Pt, Ru, etc.) for causing an electrode reaction in the anode and cathode.

Each separator is formed with a groove for supplying hydrogen or air to the entire surface of each MEA, and through holes for supplying and discharging hydrogen or air to all single cells. It functions as a channel 11 (fuel gas channel) and a cathode channel 12 (oxidant gas channel).
Then, when hydrogen is supplied to each anode via the anode flow path 11 and air is supplied to each cathode via the cathode flow path 12, an electrode reaction occurs and OCV is generated in each single cell. ing. Next, when the OCV is equal to or higher than the predetermined OCV, there is a power generation request, the FC contactor 52 described later is turned on, and the current is taken out, the fuel cell stack 10 generates power.

<Cell voltage monitor>
The cell voltage monitor 13 is a device that detects a voltage (cell voltage) for each of a plurality of single cells constituting the fuel cell stack 10, and includes a monitor main body and a wire harness that connects the monitor main body and each single cell. ing.
The monitor main body scans all single cells at a predetermined cycle, detects the cell voltage of each single cell, and calculates the lowest cell voltage V11 and the average cell voltage V12. The monitor body outputs the calculated minimum cell voltage V11 and average cell voltage V12 to the ECU 80.

<Anode system>
The anode system includes a hydrogen tank 21, a shut-off valve 22, a pressure sensor 23, a temperature sensor 24, a hydrogen sensor 25, and a humidity sensor 26.
The hydrogen tank 21 is connected to the inlet of the anode flow path 11 via a pipe 21a, a shutoff valve 22, and a pipe 22a. When the shutoff valve 22 is opened by a command from the ECU 80, hydrogen is supplied from the hydrogen tank 21 to the anode flow path 11 via the shutoff valve 22 and the like.
The outlet of the anode flow path 11 is connected to a pipe 22b, and the anode off gas discharged from the anode flow path 11 is discharged to the outside through the pipe 22b.

The pressure sensor 23, the temperature sensor 24, the hydrogen sensor 25, and the humidity sensor 26 are provided in the pipe 22b.
The pressure sensor 23 detects the pressure in the anode flow path 11 and outputs it to the ECU 80. However, the position of the pressure sensor 23 is not limited to this, and may be provided in the pipe 22a, for example.

  The temperature sensor 24 detects the temperature in the pipe 22 b as the temperature of the fuel cell stack 10 and outputs it to the ECU 80. However, the position of the temperature sensor 24 is not limited to this, and may be provided in the pipe 31b, for example.

  The hydrogen sensor 25 detects the hydrogen concentration in the pipe 22b, that is, in the anode flow path 11, and outputs it to the ECU 80. However, the position of the hydrogen sensor 25 is not limited to this, and may be provided in the pipe 22a, for example.

  The humidity sensor 26 detects the humidity in the pipe 22b, that is, in the anode flow path 11, and outputs the detected humidity to the ECU 80. However, the position of the humidity sensor 26 is not limited to this. For example, a configuration in which the humidity sensor 26 is incorporated in the fuel cell stack 10 may be used.

<Cathode system>
The cathode system includes a compressor 31.
The compressor 31 is connected to the inlet of the cathode channel 12 via a pipe 31a. When the compressor 31 is operated in accordance with a command from the ECU 80, air containing oxygen is taken in and supplied to the cathode channel 12.
The compressor 31 is connected to the fuel cell stack 10 in parallel with the load 51 and the high voltage battery 54 between the FC contactor 52 and the load 51, which will be described later, and the generated power of the fuel cell stack 10 and Alternatively, the operation is performed by the charging power of the high voltage battery 54.

  Further, the pipe 31a is provided with a humidifier (not shown) so that the air supplied to the cathode channel 12 is appropriately humidified.

  The outlet of the cathode channel 12 is connected to the pipe 31b, and the cathode off gas discharged from the cathode channel 12 is discharged to the outside through the pipe 31b.

<Scavenging system>
The scavenging system is a system that guides the scavenging gas (non-humidified air) from the compressor 31 from the cathode system to the anode system when scavenging the fuel cell stack 10 after power generation is stopped, and includes a normally closed scavenging valve 41. ing.
The piping 31a is connected to the piping 22a via the piping 41a, the scavenging valve 41, and the piping 41b. When the scavenging valve 41 is opened by a command from the ECU 80 while the compressor 31 is operating, the piping 31a A scavenging gas is introduced into the anode channel 11 and the cathode channel 12.

<Power consumption system>
The power consumption system is a system that consumes the generated power of the fuel cell stack 10, and includes a load 51 including a travel motor that is a power source of the fuel cell vehicle, an FC contactor 52 that is an ON / OFF switch, and a voltage sensor. 53 and a high voltage battery 54 capable of charging and discharging electric power.

The load 51 is connected to the output terminal of the fuel cell stack 10 via the FC contactor 52. In a state where a predetermined OCV is generated in the fuel cell stack 10, a VCU (Voltage Control Unit) (not shown) that is disposed between the load 51 and the FC contactor 52 and controls the output of the fuel cell stack 10 is provided in the ECU 80. The fuel cell stack 10 generates power when appropriately controlled by the above.
On the other hand, when the FC contactor 52 is turned off, the electrical connection between the fuel cell stack 10 and the load 51 is cut off, and the power generation of the fuel cell stack 10 is stopped. Here, the time when the FC contactor 52 is OFF is the time when the power generation of the fuel cell stack 10 is stopped.

  The voltage sensor 53 is arranged between the fuel cell stack 10 and the FC contactor 52 so as to detect the entire voltage (stack voltage) of the fuel cell stack 10 and outputs the detected stack voltage to the ECU 80. It has become.

  The high voltage battery 54 is connected between the load 51 and the FC contactor 52 in parallel to the FC contactor 52 in parallel with the load 51, and charges the surplus power of the fuel cell stack 10 or assists the fuel cell stack 10. It is supposed to be.

  Further, a DC / DC converter (not shown) for stepping down the high voltage power is connected between the load 51 and the FC contactor 52. The shut-off valve 22, the ECU 80, etc. are operated by this reduced power.

<Discharge circuit>
The discharge circuit discharges the fuel cell stack 10 after the power generation of the fuel cell stack 10 is stopped (after the FC contactor 52 is turned off), and consumes hydrogen and air remaining in the stack, and the cell voltage. The circuit includes a discharge resistor (discharge resistor 61, discharge resistor) and a discharge contactor 62 that is an ON / OFF switch.

  The discharge resistor 61 is connected in parallel with the FC contactor 52 to the fuel cell stack 10 between the fuel cell stack 10 and the FC contactor 52. The discharge contactor 62 is arranged on a parallel circuit including a discharge resistor, and is turned on / off by a command from the ECU 80.

<IG>
The IG 71 is a start switch for the fuel cell vehicle and the fuel cell system 1 and is provided around the driver's seat. Moreover, IG71 is connected with ECU80, and ECU80 detects the ON / OFF signal of IG71.

<ECU>
The ECU 80 is a control device that electronically controls the fuel cell system 1 and includes a CPU, a ROM, a RAM, various interfaces, an electronic circuit, and the like, and exhibits various functions according to programs stored therein. However, various processes are executed.

  The ECU 80 has a function of appropriately controlling the shut-off valve 22, the compressor 31, and the FC contactor 52 to start and stop power generation of the fuel cell stack 10. Further, the ECU 80 has a function of opening the scavenging valve 41 and scavenging the fuel cell stack 10 after power generation is stopped.

<ECU-discharge amount calculation function>
The ECU 80 (discharge amount calculation means) repeatedly repeats the current cell voltage (minimum cell voltage) at a predetermined timing (specifically, after a predetermined time Δt has elapsed since the discharge stop) after the fuel cell stack 10 stops generating power. V11, average cell voltage V12), anode channel pressure, anode channel hydrogen concentration (gas concentration), stack voltage and at least one of the stack voltage and the map of FIG. It has a function to calculate the correct discharge amount.
Note that the map of FIG. 3 is obtained by a preliminary test or the like and stored in the ECU 80 in advance. As shown in FIG. 3, when the cell voltage, the anode channel pressure, the hydrogen concentration, and the stack voltage increase, it is estimated that a large amount of hydrogen remains in the anode channel 11, so that the subsequent discharge amount increases. It has become.

Furthermore, the ECU 80 has a function of calculating the correction coefficient A based on at least one of the elapsed time after the IG 71 is turned off and the number of discharges and the map of FIG. 4 and correcting the discharge amount.
Note that the map of FIG. 4 is obtained by a preliminary test or the like and stored in the ECU 80 in advance. As shown in FIG. 4, when the elapsed time after turning off the IG 71 is long and the number of discharges is large, it is estimated that the amount of hydrogen remaining in the anode flow path 11 is small, and therefore the correction coefficient A is small. .
In other words, when there is little remaining hydrogen, if the battery is normally discharged, the voltage of some of the single cells may be reversed and the deterioration of the single cells may progress. When the subsequent elapsed time is long and the number of discharges is increased, the single cell can be prevented from being deteriorated by setting so as to reduce the discharge amount.

Furthermore, the ECU 80 has a function of calculating a correction coefficient B based on at least one of the current temperature of the fuel cell stack 10 and the humidity of the anode flow path 11 and the map of FIG. 5 and correcting the discharge amount. I have.
Note that the map of FIG. 5 is obtained by a preliminary test or the like and stored in the ECU 80 in advance. As shown in FIG. 5, when the temperature of the fuel cell stack 10 is high and the humidity of the anode flow path 11 is high, it is considered that current flows in the single cell due to the remaining hydrogen and air, and the single cell is likely to deteriorate. Therefore, the correction coefficient B is increased.

<ECU—Discharge execution determination function>
Further, the ECU 80 (discharge execution determining means) compares the discharge amount calculated and corrected as described above with 0, which is a predetermined discharge amount serving as a reference for starting discharge, and determines whether or not to execute discharge. It has a function to determine whether. However, the predetermined discharge amount is not limited to 0, and can be set to, for example, a value close to 0 or an amount that can be determined to suppress deterioration of a single cell.

<ECU—start control function, stop control function>
Further, the ECU 80 (start control means) has a function of turning on the discharge contactor 62 and starting the discharge of the fuel cell stack 10 when it is determined to perform the discharge as described above.
The ECU 80 (stop control means) has a function of turning off the discharge contactor 62 and stopping the discharge of the fuel cell stack 10 when it is determined that the minimum cell voltage V11 is equal to or lower than the predetermined voltage V1, as will be described later. ing.

<ECU-voltage determination function>
Further, the ECU 80 has a function of determining whether or not the current lowest cell voltage V11 is equal to or lower than a predetermined voltage V1 during the discharge of the fuel cell stack 10. The predetermined voltage V1 is set to a voltage close to 0 V, for example, in order to prevent the lowest cell voltage V11 from becoming negative.

≪Operation and operation method of fuel cell system≫
Next, with reference to FIG. 2, the operation of the fuel cell system 1 will be described together with the flow of a program (flow chart) set in the ECU 80.
When the IG 71 is turned off, the processing shown in the flowchart of FIG. 2 starts. Before the IG 71 is turned off (initial state), the shutoff valve 22 is opened, the compressor 31 is operated, the FC contactor 52 is turned on, and the fuel cell stack 10 is generating power.

  In step S101, the ECU 80 stops power generation of the fuel cell stack 10. Specifically, the ECU 80 closes the cutoff valve 22 and turns off the FC contactor 52. Note that the compressor 31 remains activated, and operates with the high voltage battery 54 as a power source after the FC contactor 52 is turned off.

In step S102, the ECU 80 scavenges the fuel cell stack 10. Specifically, the ECU 80 opens the scavenging valve 41 while operating the compressor 31 and introduces the scavenging gas (non-humidified air) into the anode channel 11 and the cathode channel 12. As a result, moisture (such as water vapor) in the anode channel 11 and the cathode channel 12 is pushed out to the outside, and replacement with scavenging gas (non-humidified air) proceeds.
Thereafter, for example, when a predetermined scavenging time has elapsed, the ECU 80 stops the compressor 31, closes the scavenging valve 41, and ends scavenging of the fuel cell stack 10.

  In step S103, the ECU 80 determines the fuel cell stack based on at least one of the current cell voltage (for example, the average cell voltage V12), the stack voltage, the pressure in the anode flow path 11, the hydrogen concentration, and the map of FIG. 10 calculates a discharge amount (power amount) that can be discharged thereafter. The unit of the discharge amount is, for example, the electric energy (Wh).

  The ECU 80 calculates the correction coefficient A based on at least one of the elapsed time after the IG 71 (FC contactor 52) is turned off and the number of discharges (0 in the first case) and the map of FIG. To do.

Next, the ECU 80 calculates the correction coefficient B based on at least one of the temperature of the fuel cell stack 10 and the humidity of the anode flow path 11 and the map of FIG.
Thereafter, the ECU 80 multiplies the discharge amount, the correction coefficient A, and the correction coefficient B to correct the discharge amount.

In step S104, the ECU 80 then determines whether or not the fuel cell stack 10 needs to be discharged. Specifically, the ECU 80 determines whether or not the corrected discharge amount is greater than 0 (predetermined discharge amount).
When the corrected discharge amount is larger than 0, it is determined that the fuel cell stack 10 needs to be discharged (S104 / Yes), and the process of the ECU 80 proceeds to step S105. On the other hand, when the corrected discharge amount is not larger than 0, it is determined that it is not necessary to execute the discharge of the fuel cell stack 10 (S104, No), and the process of the ECU 80 proceeds to step S108.

  In step S105, the ECU 80 turns on the discharge contactor 62 and starts discharging (discharging) the fuel cell stack 10. Then, hydrogen remaining in the anode flow path 11 and air remaining in the cathode flow path 12 are consumed, and the stack voltage, the lowest cell voltage V11, and the average cell voltage V12 are lowered.

In step S106, the ECU 80 determines whether or not the current lowest cell voltage V11 input from the cell voltage monitor 13 is equal to or lower than a predetermined voltage V1.
When the current lowest cell voltage V11 is equal to or lower than the predetermined voltage V1 (S106 / Yes), the process of the ECU 80 proceeds to step S107. On the other hand, when the current lowest cell voltage V11 is not equal to or lower than the predetermined voltage V1 (No in S106), the ECU 80 repeats the determination in Step S106.

  In step S107, the ECU 80 adds the number of discharges once using the internal memory.

In step S108, the ECU 80 turns off the discharge contactor 62 and stops the discharge of the fuel cell stack 10. As a result, the lowest cell voltage V11 does not drop below the predetermined voltage V1, and deterioration of the single cell can be prevented.
If the determination in step S104 is No and then the process proceeds to step S108, the ECU 80 continues to turn off the discharge contactor 62.

In step S109, the ECU 80 uses the internal clock to determine whether or not a predetermined time Δt has elapsed after step S108. The predetermined time Δt is obtained by a preliminary test and stored in the ECU 80 in advance.
If the predetermined time Δt has elapsed (S109: Yes), the processing of the ECU 80 proceeds to step S103. On the other hand, when the predetermined time Δt has not elapsed (No at S109), the ECU 80 repeats the determination at Step S109.
In addition, it is good also as a structure which increases predetermined time (DELTA) t as the frequency | count of determination of step S109 increases.

  When the predetermined time Δt has elapsed (S109 / Yes), that is, after the power generation stop of the fuel cell stack 10 (specifically, the discharge stop), the ECU 80 calculates the subsequent discharge amount again at a predetermined timing ( S103), it is determined whether or not the discharge needs to be executed (S104). If necessary (S104 / Yes), the discharge is started (S105).

≪Effect of fuel cell system≫
According to such a fuel cell system 1, the following effects can be obtained.
Even after the discharge of the fuel cell stack 10 (S108), the ECU 80 continuously calculates the subsequent discharge amount at a predetermined timing (S109), repeatedly calculates the subsequent discharge amount (S103), and executes the discharge based on the calculated discharge amount. It is determined whether or not it is necessary to perform discharge (S104). When it is determined that it is necessary to perform discharge (Yes in S104), the discharge is started again (S105).
That is, even if the OCV (minimum cell voltage V11, average cell voltage V12, stack voltage, etc.) increases after the discharge is stopped, the OCV can be decreased by discharging again.

Further, when the minimum cell voltage V11 is equal to or lower than the predetermined voltage V1 (S106 / Yes), the discharge is stopped (S108), so that the fuel cell stack 10 and the single cell can be prevented from being deteriorated by overdischarge.
Further, the subsequent discharge amount is corrected based on the elapsed time after the power generation stop of the fuel cell stack 10, the number of discharges, the temperature of the fuel cell stack 10, and the humidity of the anode flow path 11, so the discharge amount is calculated appropriately. be able to.

≪Example of fuel cell system operation≫
Next, an operation example of the fuel cell system 1 will be described with reference to FIG.
When the IG 71 is turned off, the shut-off valve 22 is closed, the FC contactor 52 is turned off, the power generation of the fuel cell stack 10 is stopped (Yes in S101), and the fuel cell stack 10 is scavenged (S102). Thereafter, it is determined that the discharge needs to be executed (Yes in S104), and the discharge is started (S105).
When the lowest cell voltage V11 reaches the predetermined voltage V1 (S106 / Yes), the discharge is stopped (S108).
Then, when the predetermined time Δt has elapsed (S109 · Yes), it is determined that the discharge needs to be performed (S104 · Yes), and thus the discharge is started again (S105).

  As mentioned above, although preferred embodiment of this invention was described, this invention is not limited to the said embodiment, For example, it can change as follows in the range which does not deviate from the meaning of this invention.

In the above-described embodiment, the cell voltage monitor 13 exemplifies the configuration for detecting the voltage (cell voltage) for each of the plurality of single cells constituting the fuel cell stack 10, but for example, there are two (predetermined number), for example. A configuration may be adopted in which a single cell is taken as a set, a voltage is detected for each set, and the cell voltage of the single cell is calculated by dividing the voltage.
Moreover, it is good also as a structure which outputs the average voltage of all sets, and the minimum voltage to ECU80 based on the voltage of two (predetermined number) single cells. In this case, the ECU 80 may perform voltage determination corresponding to step S106 based on, for example, the input minimum voltage and a predetermined voltage corresponding to the grouping.

  In the above-described embodiment, the case where the fuel cell system 1 in which the discharge system is incorporated is mounted on a fuel cell vehicle is exemplified. However, for example, the fuel cell system 1 may be incorporated in a fuel cell system mounted on a motorcycle, a train, or a ship. Good. Further, the discharge system may be incorporated in a stationary fuel cell system for home use or a fuel cell system incorporated in a hot water supply system.

It is a block diagram of the fuel cell system which concerns on this embodiment. It is a flowchart which shows operation | movement of the fuel cell system which concerns on this embodiment. It is a map which shows the relationship between a cell voltage (lowest cell voltage, average cell voltage), the pressure of an anode flow path, the hydrogen concentration of an anode flow path, a stack voltage, and the discharge amount. It is a map which shows the relationship between the elapsed time after IG OFF, the frequency | count of discharge, and the correction coefficient A. 6 is a map showing the relationship between the temperature of the fuel cell stack, the humidity of the anode flow path, and the correction coefficient B. It is a time chart which shows one operation example of a fuel cell system.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Fuel cell system 10 Fuel cell stack 11 Anode flow path 12 Cathode flow path 13 Cell voltage monitor 51 Load 61 Discharge resistance 62 Discharge contactor 80 ECU
V1 Predetermined voltage V11 Minimum cell voltage V12 Average cell voltage

Claims (3)

Discharge means for discharging the fuel cell stack in order to reduce the voltage generated by the reaction gas remaining in the fuel cell stack after the fuel cell stack in which a plurality of single cells are connected in series is stopped,
A discharge amount calculating means for calculating a subsequent discharge amount at a predetermined timing after stopping the power generation of the fuel cell stack;
Discharge execution determination means for determining whether or not to execute discharge based on the calculated discharge power amount and a predetermined discharge amount serving as a reference for starting discharge;
A start control means for controlling the discharge means to start discharge when the discharge execution determination means determines to execute discharge;
Equipped with a,
The discharge amount calculating means corrects the subsequent discharge amount based on at least one of the elapsed time after the power generation stop of the fuel cell stack and the number of discharges.
Discharge system comprising a call. Discharge means for discharging the fuel cell stack in order to reduce the voltage generated by the reaction gas remaining in the fuel cell stack after the fuel cell stack in which a plurality of single cells are connected in series is stopped,
A discharge amount calculating means for calculating a subsequent discharge amount at a predetermined timing after stopping the power generation of the fuel cell stack;
Discharge execution determination means for determining whether or not to execute discharge based on the calculated discharge power amount and a predetermined discharge amount serving as a reference for starting discharge;
A start control means for controlling the discharge means to start discharge when the discharge execution determination means determines to execute discharge;
Equipped with a,
The discharge amount calculation means corrects the subsequent discharge amount based on at least one of temperature and humidity of the fuel cell stack.
Discharge system comprising a call. Voltage determination means for determining whether a current voltage of the single cell or the predetermined number of single cells is equal to or lower than a predetermined voltage during the execution of the discharge by the discharge means;
Stop control means for controlling the discharge means to stop discharge when the current voltage is equal to or lower than the predetermined voltage;
The discharge system according to claim 1 , further comprising:

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