JP4823485B2 - FUEL CELL SYSTEM AND CONTROL METHOD FOR FUEL CELL SYSTEM - Google Patents

Description

  The present invention relates to a fuel cell system that supports power generation in a sub-freezing environment and a method for determining the internal temperature of a fuel cell stack in a sub-freezing environment.

  As shown in FIG. 4, the polymer electrolyte fuel cell 100 includes a solid polymer electrolyte membrane 101, a hydrogen electrode 102 and an oxygen electrode 103 having catalytic action provided on both sides thereof, and each electrode. Separators 104 and 105 that form supply paths for hydrogen and oxygen (included in the air), which are reaction gases, are provided between 102 and 103.

Then, hydrogen gas H ₂ supplied to the supply passage 106 formed by a separator 104, electrons e in hydrogen electrode 102 ^- the hydrogen ions H ⁺ next by releasing, hydrogen ions H ⁺ solid polymer electrolyte membrane 101 Conduct inside. On the other hand, in the oxygen electrode 103, the following equation is obtained by the oxygen gas O ₂ in the air supplied to the supply path 107 formed by the separator 105, the electron e ⁻ and the hydrogen ion H ⁺ supplied from the oxygen electrode 103. Reaction (1) occurs and water H ₂ O is produced.

1 / 2O ₂ + 2H ⁺ + 2e ⁻ → H ₂ O (1)
Here, when the fuel cell 100 is started in a sub-freezing environment, the water generated by the above formula (1) is frozen at the oxygen electrode 103 and the conductivity of the hydrogen ion H ⁺ in the polymer electrolyte membrane 101 is lowered. However, there is an inconvenience that the power generation capacity of the fuel cell 100 is lowered.

In order to eliminate such inconvenience, when starting the fuel cell stack in a sub-freezing environment, the circulation of the refrigerant in the refrigerant passage provided for cooling the fuel cell is stopped and the refrigerant is extracted from the refrigerant passage. Have been proposed (see Patent Documents 1 and 2). According to this method, heating of the fuel cell stack 100 is promoted.
JP 2000-512068 A (page 10-11) JP2003-257460A (pages 7-8)

  When the fuel cell stack is started by extracting the refrigerant in the refrigerant passage, the internal temperature of the fuel cell stack rapidly rises due to heat generated by the power generation of the fuel cell stack. If the timing for starting cooling by circulating the refrigerant is delayed, the internal temperature of the fuel cell stack exceeds the guaranteed temperature of the fuel cell stack, and the membrane electrode structure etc. rises excessively, causing deterioration of the fuel cell stack. There was an inconvenience.

  Accordingly, the present invention solves the above-described disadvantages, and suppresses an excessive temperature rise when starting the fuel cell stack in a sub-freezing environment, so that the fuel cell stack can be heated by heat generated by power generation. It is an object of the present invention to provide a system and a method for grasping the internal temperature of the fuel cell stack when starting the fuel cell stack in a sub-freezing environment.

  The present invention has been made to achieve the above object, and includes a fuel cell stack configured by connecting a plurality of polymer electrolyte fuel cells, and a refrigerant passage provided in the fuel cell stack. The present invention relates to an improvement in a fuel cell system including a refrigerant circulating means for supplying a refrigerant from an inlet and collecting the refrigerant from an outlet of the refrigerant passage to circulate the refrigerant in the refrigerant passage.

And a refrigerant temperature detecting means for detecting the temperature of the refrigerant in the refrigerant passage, and the refrigerant circulation when the fuel cell stack is activated in a state where the detected temperature of the refrigerant temperature detecting means is 0 ° C. or less. Cooling control for performing intermittent refrigerant circulation processing that alternately repeats a cooling execution cycle for circulating the refrigerant in the refrigerant passage by means and a cooling stop cycle for stopping the circulation of the refrigerant in the refrigerant passage by the refrigerant circulation means A stack internal temperature grasping means for grasping the internal temperature of the fuel cell stack based on the detected temperature of the refrigerant temperature detecting means in the cooling execution cycle, and the fuel cell grasped by the stack internal temperature grasping means Stack internal temperature monitoring means for monitoring whether the internal temperature of the stack exceeds a guaranteed temperature of the fuel cell stack; The cooling control means executes the intermittent refrigerant circulation process when the internal temperature monitoring means detects that the internal temperature of the fuel cell stack exceeds the guaranteed temperature of the fuel cell stack. And the refrigerant circulating means continuously circulates the refrigerant in the refrigerant passage, the stack internal temperature ascertained by the stack internal temperature grasping means is below the guaranteed temperature of the fuel cell stack, and , when the refrigerant temperature detected by the coolant temperature detecting means is 0 ° C or below is characterized that you continue refrigerant intermittent circulation process.

  According to the present invention, when the temperature detected by the refrigerant temperature detecting means is 0 ° C. or less and the fuel cell stack is activated, the water generated in the fuel cell can be frozen. The refrigerant intermittent circulation processing is executed by the cooling control means. In the cooling stop cycle of the refrigerant intermittent circulation process, the circulation of the refrigerant is stopped, so that the heat absorption from the fuel cell stack is reduced compared to the cooling execution cycle in which the refrigerant is circulated. Heating can be promoted.

  Further, in the cooling execution cycle, the refrigerant temperature is absorbed by the refrigerant circulating in the refrigerant passage and the temperature of the refrigerant rises, so that the refrigerant temperature detection means according to the change in the internal temperature of the fuel cell stack The temperature of the refrigerant detected by this changes. Therefore, the stack internal temperature grasping means can grasp the internal temperature of the fuel cell stack based on the temperature detected by the refrigerant temperature detecting means in the cooling execution cycle. Then, since the internal temperature of the fuel cell stack ascertained by the stack internal temperature grasping means is monitored by the stack internal temperature monitoring means, it is monitored whether the fuel cell stack exceeds the guaranteed temperature of the fuel cell stack. It can be detected that the internal temperature of the battery exceeds the guaranteed temperature.

Further , according to the present invention, when the internal temperature of the fuel cell stack exceeds the guaranteed temperature, the cooling control unit stops the execution of the refrigerant intermittent circulation process, and the refrigerant circulation unit causes the refrigerant passage to stop. A refrigerant is continuously circulated inside. As a result, the amount of heat absorbed from the fuel cell stack by the refrigerant circulating in the refrigerant passage is increased, cooling of the fuel cell stack is promoted, and the internal temperature of the fuel cell stack is rapidly lowered to reduce the fuel The battery stack can be protected.

  Further, when the execution of the intermittent refrigerant circulation process is stopped, and the continuous circulation of the refrigerant in the refrigerant passage is started by the refrigerant circulation means, the power generation prohibiting means for stopping the power generation of the fuel cell stack. It is characterized by having.

According to the present invention, by stopping the power generation of the fuel cell stack by the power generation prohibiting means, the heat generated by the power generation is eliminated, so that the decrease in the internal temperature of the fuel cell stack can be further promoted.
In addition, the refrigerant temperature detection means after a predetermined time has passed as a time required for the internal temperature of the fuel cell stack to fall below the stack guarantee temperature after the power generation prohibition means is prohibited. The refrigerant temperature is detected by the above, and when the refrigerant temperature is 0 ° C. or lower, the refrigerant intermittent circulation process is executed again.

The control method for a fuel cell system of the present invention includes a fuel cell stack configured by connecting a plurality of polymer electrolyte fuel cells, and a refrigerant from an inlet of a refrigerant passage provided in the fuel cell stack. And a refrigerant circulating means for collecting the refrigerant from the outlet of the refrigerant passage and circulating the refrigerant in the refrigerant passage, wherein the temperature of the refrigerant in the refrigerant passage is When the fuel cell stack is started in a state where the temperature is 0 ° C. or less, a cooling execution cycle for circulating the refrigerant in the refrigerant passage by the refrigerant circulation means, and the refrigerant in the refrigerant passage by the refrigerant circulation means A cooling stop cycle for stopping the circulation of the refrigerant is alternately performed, and the intermittent refrigerant circulation process is executed, and based on the temperature of the refrigerant in the refrigerant passage in the cooling execution cycle, the fuel The internal temperature of the battery stack is grasped, and when it is detected that the internal temperature of the fuel cell stack exceeds the guaranteed temperature of the fuel cell stack, execution of the intermittent refrigerant circulation process is stopped, and the refrigerant The refrigerant is continuously circulated in the refrigerant passage by the circulation means, and the stack internal temperature obtained based on the temperature of the refrigerant in the refrigerant passage is equal to or lower than the guaranteed temperature of the fuel cell stack, and the refrigerant when the temperature of the coolant in the passage is 0 ° C or below is characterized that you continue refrigerant intermittent circulation process.

According to this invention, when the fuel cell stack is started in a state where the temperature of the refrigerant in the refrigerant passage is 0 ° C. or less, the refrigerant intermittent circulation is performed so that the refrigerant is circulated intermittently in the refrigerant passage. Processing is executed. In the cooling execution cycle, since the refrigerant circulates in the fuel cell stack through the refrigerant passage, the temperature of the refrigerant in the refrigerant passage changes according to the change in the internal temperature of the fuel cell stack. . Therefore, the stack temperature of the fuel cell can be grasped based on the temperature of the refrigerant in the refrigerant passage.
Further, according to the present invention, when the internal temperature of the fuel cell stack exceeds the guaranteed temperature, the execution of the intermittent refrigerant circulation process is stopped, and the refrigerant is continuously supplied into the refrigerant passage by the refrigerant circulation means. To circulate. As a result, the amount of heat absorbed from the fuel cell stack by the refrigerant circulating in the refrigerant passage is increased, cooling of the fuel cell stack is promoted, and the internal temperature of the fuel cell stack is rapidly lowered to reduce the fuel The battery stack can be protected.

  Embodiments of the present invention will be described with reference to FIGS. FIG. 1 is an overall configuration diagram of the fuel cell system, FIG. 2 is a control flowchart at the time of starting the fuel cell stack, and FIG. 3 shows a transition of the refrigerant temperature when the refrigerant is circulated intermittently at the time of starting the fuel cell stack. It is a graph.

  As shown in FIG. 1, the fuel cell stack 1 is supplied with hydrogen from a hydrogen tank 2 through a hydrogen supply pipe 3 and with air from an air compressor 4 through an air supply pipe 5. The hydrogen supply pipe 3 is provided with a variable valve 6 for adjusting the supply amount of hydrogen and a humidifier 8 for humidifying the hydrogen, and the air supply pipe 5 is provided with a variable valve 7 for adjusting the supply amount of air and the air. A humidifier 9 is provided to humidify.

  Further, a voltage detector 10 for detecting the output voltage Vfc of the fuel cell 1, a current detector 11 for detecting the output current Ifc of the fuel cell 1, and a fuel by circulating a refrigerant in the refrigerant passage 12 connected to the fuel cell 1 A cooling pump 15 for cooling the battery 1 (corresponding to the refrigerant circulation means of the present invention), a radiator 16 provided in the middle of the refrigerant passage 12, a stack ambient temperature sensor 17 for detecting the ambient temperature Ts of the fuel cell stack 1, A refrigerant inlet temperature sensor 18 (corresponding to the refrigerant temperature detecting means of the present invention) for detecting the refrigerant temperature Twin near the inlet of the fuel cell stack 1 in the refrigerant passage 12, and a refrigerant in the vicinity of the outlet of the fuel cell stack 1 in the refrigerant passage 12 The refrigerant outlet temperature sensor 19 for detecting the temperature Twout of the fuel cell, the variable resistor 21 for controlling the output current Ifc of the fuel cell stack 1, and the operation of the fuel cell stack 1 Control to the controller 30 is provided.

  The voltage detection signal of the voltage detector 10, the current detection signal of the current detector 11, the temperature detection signal of the stack temperature sensor 17, the temperature detection signal of the refrigerant inlet temperature sensor 18, and the temperature detection signal of the refrigerant outlet temperature sensor 19 are Setting and operation of the air compressor 4, the variable valves 6 and 7, the humidifiers 8 and 9, the cooling pump 15, and the variable resistor 21 are controlled by a control signal input to the controller 30 and output from the controller 30.

  Next, the fuel cell stack 1 is formed by laminating a plurality of separators 41 and a membrane electrode structure 40 including a solid polymer electrolyte membrane, a hydrogen electrode and an oxygen electrode having catalytic action provided on both sides thereof, and a separator 41. The The membrane electrode structure 40 and the separators 41 on both sides thereof constitute one unit of fuel cell.

  Further, the controller 30 has a current control means 31 for controlling the power generation amount of the fuel cell stack 1 so that the output current Ifc of the fuel cell stack 1 matches the target current set according to the required power of the electric load. The cooling control means 32 for controlling the circulation of the refrigerant to the refrigerant passage 12 by the cooling pump 15, the stack internal temperature grasping means 33 for grasping the internal temperature of the fuel cell stack 1, and the internal temperature of the fuel cell stack 1 is the fuel cell stack 1 The internal temperature grasping means 34 for monitoring whether or not the guaranteed temperature of the fuel cell stack 1 is exceeded, and the power generation for prohibiting the power generation of the fuel cell stack 1 when the internal temperature of the fuel cell stack 1 exceeds the guaranteed temperature of the fuel cell stack 1 Prohibiting means 35 is provided.

  Here, when the fuel cell stack 1 generates power, a chemical reaction occurs between hydrogen and oxygen (which are contained in the air), which are the reaction gases, and current is supplied to the variable resistor 21 and other electric loads (not shown). Supplied. Further, water is generated along with the chemical reaction. Then, when the fuel cell stack 1 is started in a sub-freezing environment, if water generated by the chemical reaction is frozen on the surface of the membrane electrode structure 40 or the like, the hydrogen ion permeability in the membrane electrode structure 40 decreases. As a result, the fuel cell stack 1 cannot be started. Alternatively, the power generation capacity of the fuel cell stack 1 is reduced.

  Therefore, the cooling control means 32, the stack internal temperature monitoring means 34, and the power generation prohibiting means 35 provided in the controller 30 execute processing for coping with activation of the fuel cell stack 1 in a sub-freezing environment. The process will be described below according to the flowchart shown in FIG.

  When the start instruction of the fuel cell stack 1 is given, the controller 30 determines whether or not the detected temperature Twin of the refrigerant in the refrigerant passage 12 by the refrigerant inlet temperature sensor 18 exceeds 0 ° C. in STEP 1. Then, when Twin exceeds 0 ° C., there is no possibility that the generated water will freeze, so the process branches to STEP 20 and “normal current output control” is executed by the current control means 31. In “normal current output control”, the current control means 31 controls the supply flow rates of hydrogen and air to the fuel cell stack 1 so as to obtain the output current Ifc corresponding to the required current from the electric load.

  On the other hand, when the detected temperature Twin of the refrigerant inlet temperature sensor 18 is 0 ° C. or less in STEP 1, the process proceeds to STEP 2, and the controller 30 starts to introduce the reaction gas (hydrogen and air) into the fuel cell stack 1. In the next STEP 3, the cooling control means 32 operates the cooling pump 15 to start circulation of the refrigerant in the refrigerant passage 12, and in STEP 4, the current control means 31 starts current output from the fuel cell stack 1. .

  Here, in a state where the refrigerant circulates in the refrigerant passage 12, the refrigerant absorbs heat from the inside of the fuel cell stack 1 when passing through the refrigerant passage 12 inside the fuel cell stack 1. It changes according to the internal temperature of the battery stack 1.

  Therefore, the stack internal temperature grasping means 33 measures the temperature Twin of the refrigerant in the vicinity of the inlet of the fuel cell stack 1 in the refrigerant passage 12 by the refrigerant inlet temperature sensor 18 in STEP 5, and is set in advance to STEP in STEP 6 by experiment or simulation. The correction value x is added to determine the internal temperature Tse (Tse = Twin + x) of the fuel cell stack 1.

  In the next STEP 7, when the internal temperature Tse of the fuel cell stack 1 does not exceed the guaranteed temperature of the fuel cell stack 1, the process proceeds to STEP 8. STEP8 to STEP11 are processes by the refrigerant control means 32. The refrigerant control means 32 proceeds to STEP9 when the refrigerant temperature Twin is 0 ° C. or less in STEP8, stops the refrigerant pump 15, and the refrigerant in the refrigerant passage 12 is processed. Stop circulation.

  Then, in STEP 10, the passage of a predetermined time is waited, and in STEP 11, the refrigerant control means 32 activates the cooling pump 15 to restart the circulation of the refrigerant in the refrigerant passage 12, and the process returns to STEP 5. On the other hand, when the refrigerant temperature Twin exceeds 0 ° C. in STEP 8, the process branches to STEP 40 and “normal current output control” is executed.

  Thereby, the processing of STEP5 to STEP11 is repeatedly executed until the temperature Twin of the refrigerant exceeds 0 ° C. in STEP8, and the “cooling execution cycle” for circulating the refrigerant in the refrigerant passage 12 and the circulation of the refrigerant in the refrigerant passage are performed. A “refrigerant intermittent circulation process” is executed in which a “cooling stop cycle” to be stopped is repeatedly executed alternately.

FIG. 3 is a graph showing the transition of the refrigerant temperature Twin when the processing of STEP5 to STEP11 is repeated. The vertical axis is set to the refrigerant temperature Twin, and the horizontal axis is set to the time axis t. Then, t ₁₀ , t ₁₂ , and t ₁₄ are times when the refrigerant circulation in the refrigerant passage 12 is started in STEP ₁₁ of FIG. 2, and t ₁₁ , t ₁₃ , and t ₁₅ are in the refrigerant passage 12 in STEP 9 of FIG. This is the point in time when the circulation of the refrigerant is stopped. Tco is a guaranteed temperature of the fuel cell stack 1.

In β ₁ (t _{11 to} t ₁₂ ) and β ₂ (t _{13 to} t ₁₄ ), which are “cooling stop cycles”, the circulation of the refrigerant in the refrigerant passage 12 stops and the refrigerant is absorbed in the fuel cell stack 1. Since the amount of heat decreases, heating of the fuel cell stack 1 due to heat generated by power generation is promoted. As a result, it is possible to prevent the generated water from being frozen near the membrane electrode structure 41 of the fuel cell and causing the power generation capacity of the fuel cell stack 1 to be reduced.

In addition, in α ₁ (t _{10 to} t ₁₁ ), α ₂ (t _{12 to} t ₁₃ ), and α ₃ (t _{14 to} t ₁₅ ) which are “cooling execution cycles”, the temperature of the refrigerant Twin is the fuel cell stack 1. 2, the stack internal temperature grasping means 33 can estimate the internal temperature Tse of the fuel cell stack 1 based on Twin.

  When the internal temperature Tse of the fuel cell stack 1 exceeds the guaranteed temperature of the fuel cell stack 1 in STEP 7 of FIG. 2, the process branches to STEP 30. At this time, because the refrigerant is circulated in the refrigerant passage 12 by the processing of STEP 11, the execution of the “refrigerant intermittent circulation process” is stopped and the refrigerant continuously circulates. Cooling of the inside of the stack 1 is promoted. In STEP 30, the power generation prohibiting unit 35 stops outputting the current from the fuel cell stack 1, thereby eliminating the heat generated by the power generation, so that the temperature in the fuel cell 1 can be quickly reduced.

  Then, in the subsequent STEP 31, the process proceeds to STEP 32 after the elapse of a predetermined time, and the refrigerant temperature Twin is measured by the refrigerant inlet temperature sensor 18 and then proceeds to STEP 8. The predetermined time in STEP 31 is the time required for the internal temperature of the fuel cell stack 1 to fall below the guaranteed stack temperature when the power generation of the fuel cell stack 1 is stopped and the refrigerant is circulated in the refrigerant passage 12. Determined.

  In the present embodiment, the refrigerant inlet temperature sensor 18 is used as the refrigerant temperature detecting means of the present invention, and the temperature of the refrigerant in the refrigerant passage 12 is measured by the detected temperature Twin of the refrigerant inlet temperature sensor 18, but the refrigerant outlet The temperature sensor 19 may be used to measure the temperature of the refrigerant in the refrigerant passage 12 based on the detected temperature Twout of the refrigerant outlet temperature sensor 19.

  Further, in this embodiment, when the internal temperature Tse of the fuel cell stack 1 exceeds the guaranteed temperature of the fuel cell stack 1 in STEP 7 of FIG. 2, the process branches to STEP 30 and the current output of the fuel cell stack 1 is stopped. However, even if the current output of the fuel cell stack 1 is continued, the effect of the present invention can be obtained.

  Further, abnormality notification may be performed when the internal temperature Tse of the fuel cell stack 1 exceeds the guaranteed temperature of the fuel cell stack 1 in STEP 7 of FIG.

1 is an overall configuration diagram of a fuel cell system. The control flowchart at the time of starting of a fuel cell stack. The graph which showed transition of refrigerant temperature when refrigerant is circulated intermittently at the time of starting of a fuel cell stack. The structure diagram of a fuel cell.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Fuel cell stack, 2 ... Hydrogen tank, 3 ... Hydrogen supply pipe, 4 ... Air compressor, 5 ... Air supply pipe, 6, 7 ... Variable valve, 8, 9 ... Humidifier, 10 ... Voltage detector, 11 ... Current detector, 12 ... refrigerant passage, 15 ... cooling pump, 17 ... stack temperature sensor, 18 ... refrigerant inlet temperature sensor, 19 ... refrigerant outlet temperature sensor, 21 ... variable resistance, 30 ... controller, 31 ... current control means, 32 ... Cooling control means, 33 ... Stack internal temperature grasping means, 34 ... Stack internal temperature monitoring means, 35 ... Power generation prohibiting means

Claims (4)

A fuel cell stack configured by connecting a plurality of polymer electrolyte fuel cells, and a refrigerant is supplied from an inlet of a refrigerant passage provided in the fuel cell stack and a refrigerant is recovered from an outlet of the refrigerant passage. A fuel cell system comprising a refrigerant circulation means for circulating the refrigerant in the refrigerant passage,
Refrigerant temperature detecting means for detecting the temperature of the refrigerant in the refrigerant passage;
A cooling execution cycle in which the refrigerant circulating means circulates the refrigerant in the refrigerant passage when the fuel cell stack is activated in a state where the temperature detected by the refrigerant temperature detecting means is 0 ° C. or less; and the refrigerant circulation A cooling control means for performing intermittent refrigerant circulation processing that alternately repeats a cooling stop cycle for stopping circulation of the refrigerant in the refrigerant passage by means;
Stack internal temperature grasping means for grasping the internal temperature of the fuel cell stack based on the detected temperature of the refrigerant temperature detecting means in the cooling execution cycle;
Stack internal temperature monitoring means for monitoring whether or not the internal temperature of the fuel cell stack ascertained by the stack internal temperature grasping means exceeds a guaranteed temperature of the fuel cell stack,
When the internal temperature of the fuel cell stack is detected by the stack internal temperature monitoring unit to exceed the guaranteed temperature of the fuel cell stack, the cooling control unit stops the intermittent refrigerant circulation process. Then, the refrigerant is continuously circulated in the refrigerant passage by the refrigerant circulation means ,
When the stack internal temperature ascertained by the stack internal temperature grasping means is lower than the guaranteed temperature of the fuel cell stack and the refrigerant temperature detected by the refrigerant temperature detecting means is 0 ° C. or lower, fuel cell system, characterized that you continue intermittent circulation process. Power generation prohibiting means for stopping power generation of the fuel cell stack when execution of the intermittent refrigerant circulation process is stopped and continuous circulation of the refrigerant into the refrigerant passage by the refrigerant circulation means is started. the fuel cell system of claim 1, wherein the a. After a predetermined time has elapsed as a time required for the internal temperature of the fuel cell stack to fall below the stack guarantee temperature after the power generation by the power generation prohibiting means is prohibited, the refrigerant temperature detecting means The fuel cell system according to claim 2, wherein the temperature is detected, and when the refrigerant temperature is 0 ° C. or lower, the refrigerant intermittent circulation process is executed again. A fuel cell stack configured by connecting a plurality of polymer electrolyte fuel cells, and a refrigerant is supplied from an inlet of a refrigerant passage provided in the fuel cell stack and a refrigerant is recovered from an outlet of the refrigerant passage. And a control method for a fuel cell system comprising a refrigerant circulation means for circulating the refrigerant in the refrigerant passage,
A cooling execution cycle for circulating the refrigerant in the refrigerant passage by the refrigerant circulation means when the fuel cell stack is activated in a state where the temperature of the refrigerant in the refrigerant passage is 0 ° C. or less; and the refrigerant circulation A refrigerant intermittent circulation process that alternately repeats a cooling stop cycle for stopping circulation of the refrigerant in the refrigerant passage by means,
Based on the temperature of the refrigerant in the refrigerant passage in the cooling execution cycle, the internal temperature of the fuel cell stack is grasped, and it is detected that the internal temperature of the fuel cell stack exceeds the guaranteed temperature of the fuel cell stack. When this is done, the execution of the refrigerant intermittent circulation process is stopped, and the refrigerant is continuously circulated in the refrigerant passage by the refrigerant circulation means .
When the stack internal temperature obtained based on the temperature of the refrigerant in the refrigerant passage is equal to or lower than the guaranteed temperature of the fuel cell stack and the temperature of the refrigerant in the refrigerant passage is equal to or lower than 0 ° C, control method for a fuel cell system characterized that you continue refrigerant intermittent circulation process.

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