JP2008204900A - Fuel cell system, and control method of fuel cell - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a technology capable of accurately detecting an operating state of a fuel cell, and suitably controlling in accordance with it, in a fuel cell system. <P>SOLUTION: The fuel cell system equipped with a fuel cell is provided with a cooling medium flow channel passing inside a fuel cell to have a cooling medium flow for cooling the fuel cell, a cooling medium flow stop part for stopping the flow of the cooling medium in the cooling medium flow channel, a pressure detection part for detecting pressure of the cooling medium in a sealed space inside the fuel cell or between the fuel cell and the cooling medium flow stop part with the flow of the cooling medium in a stopped state in the cooling medium flow channel, and an operation control part for controlling operation of the fuel cell in accordance with the pressure detected by the pressure detection part. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a fuel cell system that controls a fuel cell according to the operating state of the fuel cell.

  2. Description of the Related Art Conventionally, a fuel cell system includes a cooling medium circulation channel that circulates a cooling medium and cools the fuel cell. In such a fuel cell system, the operating state of the fuel cell is detected, and various controls are performed on the fuel cell accordingly. As a method for detecting the operating state of the fuel cell, for example, the internal temperature of the fuel cell (hereinafter also referred to as the fuel cell temperature) is detected. In this case, in the fuel cell system, for example, the temperature of the coolant flowing through the coolant circulation path is detected as the fuel cell temperature (see Patent Document 1 below).

JP 2005-302515 A

By the way, in the fuel cell system as described above, for example, under circumstances such as the following (1) to (3), the circulation of the cooling medium is stopped in the cooling medium circulation flow path in order to raise the fuel cell temperature. There is a case to let you. As described above, when the circulation of the cooling medium is stopped, there is a possibility that temperature unevenness occurs in the cooling medium in the cooling medium circulation flow path.
(1) At low temperature startup of the fuel cell (2) When flooding behavior is detected inside the fuel cell (3) During scavenging of the fuel cell

  Then, in the method of detecting the temperature of the cooling medium as the fuel cell temperature as described above, if the temperature unevenness occurs in the cooling medium as described above, the fuel cell temperature may not be detected accurately. Along with this, a problem occurs in the control of the fuel cell, and as a result, the power generation efficiency of the fuel cell may be reduced.

  In the fuel cell system, the above problem can naturally occur even when the circulation of the cooling medium is stopped in the cooling medium circulation flow path in cases other than the above (1) to (3).

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a technology capable of accurately detecting the operation state of a fuel cell and performing appropriate control accordingly in a fuel cell system. To do.

  In order to achieve at least a part of the above object, a fuel cell system of the present invention is a fuel cell system including a fuel cell, and passes a cooling medium for cooling the fuel cell through the inside of the fuel cell. A cooling medium flow path; a refrigerant flow stopping portion that stops the flow of the cooling medium in the cooling medium flow path; and a state in which the flow of the cooling medium is stopped in the cooling medium flow path Alternatively, a pressure detection unit that detects the pressure of the cooling medium in a sealed space between the fuel cell and the refrigerant flow stop unit, and the operation of the fuel cell according to the pressure detected by the pressure detection unit And a driving control unit that performs control.

  According to the fuel cell system configured as described above, it is possible to accurately detect the operation state of the fuel cell and perform appropriate control accordingly.

  The fuel cell system may further include a warm-up unit that warms up the fuel cell, and the pressure detection unit is in a state where the flow of the cooling medium is stopped by the refrigerant flow stop unit, It is preferable to include a first detection unit that detects the pressure of the cooling medium that has been raised by being warmed up.

  In this way, it is possible to accurately know the state of the fuel cell due to the effect of warm-up. As a result, the operation control unit can perform operation control of the fuel cell at an appropriate timing according to the detection result of the coolant pressure.

  In the fuel cell system, when the pressure of the coolant detected by the first detector is greater than a second threshold, the operation control unit cools toward the fuel cell in the coolant flow path. You may make it start flowing a medium.

  If it does in this way, a cooling medium can be made to flow toward a fuel cell at an appropriate timing with a pressure of a cooling medium detected by the 1st detecting part.

  In the fuel cell system, when the fuel cell system is activated, a pressure of the cooling medium is detected, and when the pressure is equal to or lower than a first threshold, a first temperature at which it is determined that the temperature of the fuel cell needs to be increased is determined. An increase determination unit may be provided, and the warm-up unit may warm up the fuel cell when the second temperature increase determination unit determines that the temperature of the fuel cell needs to be increased.

  In this way, the fuel cell can be appropriately warmed up when the fuel cell system is started.

  The fuel cell system further includes a second temperature increase determination unit that determines that the temperature of the fuel cell needs to be increased when flooding occurs in the fuel cell, wherein the second temperature increase determination unit When it is determined that the battery temperature needs to be increased, the fuel cell may be warmed up. In this way, the fuel cell can be appropriately warmed up during flooding.

  The fuel cell system preferably includes a scavenging processing unit that performs a scavenging process when the warm-up unit is generating power in the fuel cell when the fuel cell system is stopped.

  In this way, even when the scavenging process is performed while warming up the fuel cell, the operating state of the fuel cell can be accurately detected. As a result, appropriate control can be performed accordingly.

  In the fuel cell system, it is preferable that the operation control unit stops the fuel cell system when the pressure of the cooling medium detected by the first detection unit is larger than a third threshold value. In this way, the fuel cell system can be stopped appropriately.

  The fuel cell system includes a scavenging determination unit that determines whether or not to perform the scavenging process when the fuel cell system is stopped, and the scavenging processing unit includes the scavenging determination unit that performs the scavenging process. When it is determined, it is preferable to perform the scavenging process while generating power in the fuel cell. If it does in this way, it can control performing scavenging processing appropriately.

  In the fuel cell system, when the scavenging determination unit that determines whether or not to perform the scavenging process of the fuel cell and the scavenging determination unit determine that the scavenging process of the fuel cell is necessary, the power generation of the fuel cell A stop control unit that stops the flow of the cooling medium after the stop control unit stops power generation of the fuel cell, and the coolant flow stopping unit stops the flow of the cooling medium. A second detection unit that detects the pressure of the cooling medium, and the operation control unit generates power when the pressure of the cooling medium detected by the second detection unit is smaller than a fourth threshold value. It is preferable to execute a scavenging process that is not accompanied.

  In this way, the state of the fuel cell due to the influence of heat dissipation can be accurately known. As a result, the operation control unit can perform operation control of the fuel cell at an appropriate timing according to the detection result of the coolant pressure.

  In the fuel cell system, it is preferable that the warm-up unit warms the fuel cell by causing the fuel cell to generate electric power. In this way, the fuel cell can be appropriately warmed up.

  In the fuel cell system, the scavenging determination unit determines whether or not to perform the scavenging process of the fuel cell based on at least one of date data or air temperature data representing an external air temperature when the fuel cell system is activated. Is preferably determined. In this way, the scavenging process determination unit can appropriately determine whether or not to perform the scavenging process of the fuel cell.

In order to achieve at least a part of the above object, a control method for a fuel cell system according to the present invention includes:
A control method of a fuel cell system comprising a cooling medium flow path that passes through a fuel cell and flows a cooling medium for cooling the fuel cell, wherein the flow of the cooling medium is stopped in the cooling medium flow path And the pressure of the cooling medium in the fuel cell or in a sealed space between the fuel cell and the refrigerant flow stopping portion in a state where the flow of the cooling medium is stopped in the cooling medium flow path. And a step of performing operation control of the fuel cell according to the detected pressure.

  According to the control method of the fuel cell system configured as described above, it is possible to accurately detect the operating state of the fuel cell and perform appropriate control accordingly.

  It should be noted that the present invention can be realized as an aspect of other device inventions such as a fuel cell control device in addition to the fuel cell system described above. In addition, the present invention can be realized in the form of a method invention such as the control method of the fuel cell system described above. Further, aspects as a computer program for constructing those methods and apparatuses, aspects as a recording medium recording such a computer program, data signals embodied in a carrier wave including the computer program, etc. It can also be realized in various ways.

  Further, when the present invention is configured as a computer program or a recording medium that records the program, the entire program for controlling the operation of the apparatus may be configured, or only the portion that performs the functions of the present invention. It may be configured.

Hereinafter, embodiments of the present invention will be described in the following order based on examples.
A. Example:
A1. Configuration of the fuel cell system 100:
FIG. 1 is a block diagram showing a configuration of a fuel cell system 100 as an embodiment of the present invention. The fuel cell system 100 of the present embodiment mainly includes a fuel cell 10, a hydrogen tank 20, a compressor 30, a purge valve 40, a hydrogen circulation pump 50, a refrigerant circulation pump 55, a refrigerant flow stop valve 71, 72, a radiator 70, a load 80, a pressure sensor 90, a voltage sensor 95, a hydrogen shut-off valve 200, and a control circuit 400.

  The fuel cell 10 is a polymer electrolyte fuel cell and has a stack structure in which a plurality of single cells (hereinafter simply referred to as cells) are stacked. Each cell has a configuration in which an anode (not shown) and a cathode (not shown) are arranged with an electrolyte membrane (not shown) interposed therebetween. The fuel cell 10 supplies a fuel gas containing hydrogen to the anode side of each cell, and supplies an oxidizing gas containing oxygen to the cathode side, whereby an electrochemical reaction proceeds to generate an electromotive force. The fuel cell 10 supplies the generated electric power to a load 80 connected to the fuel cell 10 (see FIG. 1). As the fuel cell 10, various types such as a hydrogen separation membrane fuel cell, an alkaline aqueous electrolyte type, a phosphoric acid electrolyte type, or a molten carbonate electrolyte type, in addition to the above-described solid polymer type fuel cell. The fuel cell can be used. Hereinafter, in the fuel cell 10, a flow path through which the fuel gas flows is referred to as an anode flow path 25, and a flow path through which the oxidizing gas flows is referred to as a cathode flow path 35.

  The hydrogen tank 20 is a storage device that stores high-pressure hydrogen gas, and is connected to the anode flow path 25 of the fuel cell 10 via the fuel gas supply flow path 24. On the fuel gas supply flow path 24, a hydrogen cutoff valve 200 and a pressure regulating valve (not shown) are provided in order from the hydrogen tank 20. By opening the hydrogen shut-off valve 200, hydrogen gas is supplied to the fuel cell 10 as fuel gas. Instead of the hydrogen tank 20, hydrogen may be generated by a reforming reaction using alcohol, hydrocarbon, aldehyde or the like as a raw material and supplied to the anode side.

  The anode flow path 25 of the fuel cell 10 is connected to a fuel gas discharge flow path 26, and a purge valve 40 is provided on the fuel gas discharge flow path 26. During operation of the fuel cell system 100, the purge valve 40 is periodically opened, so that the fuel gas after being subjected to the electrochemical reaction at the anode is periodically replaced with the fuel gas discharge channel 26, the purge valve. It is discharged to the outside through 40.

  In the fuel gas discharge channel 26, a gas circulation channel 27 connected to the fuel gas supply channel 24 is provided from a position upstream with respect to the flow direction in which the fuel gas is discharged from the purge valve 40. A hydrogen circulation pump 50 is provided on the gas circulation channel 27. The gas circulation channel 27 guides the fuel gas sent out by the hydrogen circulation pump 50 to the fuel gas supply channel 24. As described above, the gas circulation channel 27 plays a role of circulating the fuel gas. In this way, the hydrogen gas contained in the fuel gas circulates and is used again for power generation as the fuel gas.

  The compressor 30 is connected to the cathode flow path 35 of the fuel cell 10 via the oxidizing gas supply flow path 34, compresses air, and supplies it as an oxidizing gas to the cathode. Further, the cathode channel 35 is connected to the oxidizing gas discharge channel 36, and the oxidizing gas after being subjected to the electrochemical reaction at the cathode passes through the oxidizing gas discharge channel 36 to the outside of the fuel cell system 100. To be discharged.

  In addition, the fuel cell system 100 includes a refrigerant circulation passage 75 for circulating a cooling medium (hereinafter also referred to as a refrigerant) for cooling the fuel cell 10. A part of the refrigerant circulation passage 75 passes through the inside of the fuel cell 10, and heat exchange is performed between the refrigerant and the fuel cell 10. In the refrigerant circulation channel 75, a channel passing through the inside of the fuel cell 10 is also referred to as a fuel cell cooling channel 17. A radiator 70, a refrigerant circulation pump 55, and refrigerant flow stop valves 71 and 72 are provided on the refrigerant circulation channel 75. In addition, as a refrigerant | coolant, water, the liquid mixture (antifreeze) of water and ethylene glycol, etc. can be used.

  The refrigerant circulation pump 55 is a pump for circulating the refrigerant in the refrigerant circulation passage 75. In FIG. 1, the circulation direction of the refrigerant (hereinafter also simply referred to as the circulation direction) is clockwise.

  The radiator 70 is provided in the refrigerant circulation passage 75 upstream of the refrigerant circulation pump 55 in the circulation direction, and cools the refrigerant warmed by the fuel cell by exchanging heat with the outside air.

  The refrigerant flow stop valve 71 is a shut-off valve, and is provided in the refrigerant circulation passage 75 between the radiator 70 and the fuel cell 10 and at a position downstream of the radiator 70 in the circulation direction. The refrigerant stop valve 72 is also a shut-off valve, and is provided in the refrigerant circulation passage 75 between the radiator 70 and the fuel cell 10 and at a position upstream of the radiator 70 in the circulation direction. Here, in the refrigerant circulation flow path 75, in particular, the flow path between the refrigerant flow stop valve 71 and the refrigerant flow stop valve 72 and including the fuel cell cooling flow path 17 is referred to as the pressure detection flow path 75A. Call.

  The pressure sensor 90 is a sensor that is provided between the fuel cell 10 and the refrigerant stop valve 72 in the pressure detection flow path 75A and detects the pressure of the refrigerant in the pressure detection flow path 75A. When the refrigerant flow stop valve 71 and the refrigerant flow stop valve 72 are closed, the pressure detection flow path 75A is a sealed space, that is, the refrigerant flow is stopped, and heat energy is transmitted from the fuel cell 10. And the pressure rises accordingly. The pressure detection unit 410 described later detects the pressure of the refrigerant in the pressure detection flow path 75A via the pressure sensor 90. The voltage sensor 95 is a sensor for detecting the electromotive voltage of each cell in the fuel cell 10.

  The load 80 is connected when the fuel cell 10 generates power. At that time, the control circuit 400, which will be described later, determines the power generation amount according to the power demand from the load 80, and adjusts the oxidizing gas supply amount, the fuel gas supply amount, and the like based on the determined power generation amount, Feed the amount. Examples of the load 80 include a motor and a secondary battery.

  The control circuit 400 is configured as a logic circuit centered on a microcomputer, and more specifically, a CPU (not shown) that executes predetermined calculations according to a preset control program and various arithmetic processes performed by the CPU. A ROM (not shown) in which control programs and control data necessary for the above are stored in advance, and a RAM (not shown) in which various data necessary for performing various arithmetic processes in the CPU are temporarily read and written. And an input / output port (not shown) for inputting / outputting various signals. The control circuit 400 controls the compressor 30, the purge valve 40, the hydrogen circulation pump 50, the refrigerant circulation pump 55, the refrigerant flow stop valves 71 and 72, the hydrogen cutoff valve 200, and the like, that is, the entire fuel cell system 100. Take control.

  The control circuit 400 also serves as a pressure detection unit 410, a temperature rise determination unit 420, a refrigerant flow control unit 430, an operation control unit 440, a power generation unit 450, a stop control unit 460, and a scavenging determination unit 470. It functions to execute a fuel cell system start process, a flooding suppression process, a fuel cell system stop process, and the like, which will be described later. Further, the control circuit 400 includes a date data storage unit 480 that stores date data representing the date of the day. This date data is updated daily by the control circuit 400.

The fuel cell system 100 of the present embodiment executes the following three processes (1) to (3).
(1) Fuel cell system start processing performed when the fuel cell system 100 is started (2) Flooding suppression processing performed during normal power generation (3) Fuel cell system stop processing performed at the end of start of the fuel cell system 100 This will be described below in order.

A2. Fuel cell system startup processing:
FIG. 2 is a flowchart of the fuel cell system activation process performed by the fuel cell system 100 of the present embodiment. First, preconditions for this process will be described. Prior to the start of the fuel cell system activation process, the refrigerant stop valve 71, the refrigerant stop valve 72, the hydrogen cutoff valve 200, and the purge valve 40 are closed. Further, the refrigerant circulation pump 55, the hydrogen circulation pump 50, and the compressor 30 are not driven. Therefore, the pressure detection flow path 75A is a sealed space made of a refrigerant. In this fuel cell system activation process, at the time of activation, the control circuit 400 makes a predetermined determination, and if necessary, warms up the fuel cell 10.

  When the fuel cell system activation process is started, first, the temperature rise determination unit 420 detects the coolant pressure P1 in the pressure detection flow path 75A from the pressure sensor 90 (FIG. 2, step S10). Then, the temperature rise determination unit 420 determines whether or not the cooling medium pressure P1 is greater than a predetermined threshold value αth (FIG. 2, step S20). When the temperature increase determination unit 420 determines that the coolant pressure P1 is greater than the threshold value αth (FIG. 2, step S20: YES), the operation control unit 440 determines that the fuel cell 10 does not need to be warmed up. Then, the refrigerant flow stop valve 71 and the refrigerant flow stop valve 72 are opened, the refrigerant circulation pump 55 is driven, and the refrigerant circulation is started in the refrigerant circulation passage 75 (FIG. 2, step S60). Thereafter, the control circuit 400 starts normal power generation.

  On the other hand, when the temperature increase determination unit 420 determines that the coolant pressure P1 is equal to or less than the threshold value αth (FIG. 2, step S20: NO), the power generation unit 450 causes the fuel cell 10 to generate power (FIG. 2, step S30). ). Specifically, the power generation unit 450 connects the fuel cell 10 and the load 80. Then, the power generation unit 450 drives the compressor 30 to supply the oxidizing gas to the cathode side of the fuel cell 10, drives the hydrogen circulation pump 50, and opens the hydrogen shut-off valve 200 so that the fuel is supplied to the anode side. Supply gas. Thereby, power generation of the fuel cell 10 is started, and the fuel cell 10 is warmed up (that is, thermal energy is given to the fuel cell 10).

  Subsequently, the pressure detection unit 410 detects the cooling medium pressure P2 in the pressure detection flow path 75A from the pressure sensor 90 (FIG. 2, step S40). Then, the operation control unit 440 determines whether or not the cooling medium pressure P2 is greater than a predetermined threshold value αth (FIG. 2, step S50). When the operation control unit 440 determines that the coolant pressure P2 is equal to or lower than the threshold value αth (FIG. 2, step S50: NO), the control circuit 400 determines that the fuel cell 10 is not warmed up sufficiently, Return to processing. The threshold value αth is determined based on a specific design of the fuel cell system 100.

  When the coolant pressure P2 is greater than the threshold value αth (FIG. 2, step S50: YES), the operation control unit 440 determines that the fuel cell 10 is sufficiently warmed up, and the refrigerant circulation channel 75 Circulation is started (FIG. 2, step S60). Thereafter, the control circuit 400 starts normal power generation.

  By the way, for example, when heat energy (hereinafter referred to as transmission energy) is transmitted from the outside to a space (sealed space) in which the refrigerant is enclosed, the temperature and pressure of the refrigerant increase due to the transmission energy. To do. However, in this case, in the refrigerant, temperature unevenness occurs for a certain period of time, and a portion far from the transmission portion of the transmission energy is not immediately affected by the transmission energy. If it does so, if the temperature of the part far from a transmission part is measured and it is set as the typical temperature of a refrigerant | coolant, there existed a possibility that the exact state of a refrigerant | coolant could not be known. On the other hand, in this refrigerant, the pressure is easily affected by transmitted energy instantaneously, that is, the refrigerant tends to be in an equilibrium state quickly. Therefore, if the pressure in the refrigerant is measured, the accurate state of the refrigerant can be known.

  Therefore, as described above, the fuel cell system 100 of the present embodiment is in the state where the refrigerant flow is stopped (sealed state) in the pressure detection flow path 75A in the fuel cell system start-up process (FIG. 2) described above. The cooling medium pressure P2 is detected. In this way, it is possible to accurately know the state of the fuel cell due to the influence of warm-up (power generation). Then, according to the detection result of the cooling medium pressure P2, the refrigerant circulation channel 75 starts to circulate the refrigerant and starts normal power generation. In this way, it is possible to start the circulation of the refrigerant in the refrigerant circulation passage 75 or start the normal power generation at an appropriate timing. In other words, it is possible to accurately detect the operating state of the fuel cell based on the coolant pressure P2 and perform appropriate control accordingly.

A3. Flooding suppression processing:
FIG. 3 is a flowchart of the flooding suppression process performed by the fuel cell system 100 of the present embodiment. First, preconditions for this process will be described. Prior to the start of the flooding suppression process, the refrigerant stop valve 71, the refrigerant stop valve 72, and the hydrogen shut-off valve 200 are opened, and the purge valve 40 is closed. The refrigerant circulation pump 55, the hydrogen circulation pump 50 and the compressor 30 are driven. Therefore, the pressure detection flow path 75A is in a state where the refrigerant flows. This flooding suppression process is performed at any time during normal power generation, and when the fuel cell 10 is in a flooding state, the fuel cell 10 is warmed up, and the evaporation of water inside each cell is promoted to suppress flooding.

  In the flooding suppression process, the temperature rise determination unit 420 determines whether or not the fuel cell 10 is in the flooding state (FIG. 3, step S110). Specifically, the temperature rise determination unit 420 detects the electromotive voltage Va of each cell of the fuel cell 10 from the voltage sensor 95, and calculates the average electromotive voltage Vav from the electromotive voltage Va of each cell. Then, the temperature rise determination unit 420 sets a reference voltage Vk, which is a certain level lower voltage, from the calculated average electromotive voltage Vav, compares the electromotive voltage Va of each cell with the reference voltage Vk, and determines the electromotive voltage Va. A cell lower than the reference voltage Vk is determined to be in a flooding state. Hereinafter, a cell in the flooding state is referred to as a flooding cell. Then, the temperature increase determination unit 420 obtains the total number Sr of flooding cells, and determines that the fuel cell 10 is in the flooding state when the total number Sr of flooding cells is greater than the predetermined number Sth. The predetermined number Sth is appropriately determined depending on the specific design contents (number of cells, etc.) of the fuel cell 10.

  When the temperature rise determination unit 420 determines that the fuel cell 10 is not in the flooding state (FIG. 3, step S110: NO), the process of step S110 is repeated.

  When the temperature rise determination unit 420 determines that the fuel cell 10 is flooded (FIG. 3, step S110: YES), the refrigerant flow control unit 430 stops driving the refrigerant circulation pump 55 and also uses the refrigerant flow valve 72. Then, the refrigerant stop valve 71 is closed, and the refrigerant circulation is stopped in the refrigerant circulation passage 75 (FIG. 3, step S120).

  In this case, the power generation unit 450 causes the fuel cell 10 to continue power generation to warm up the fuel cell 10 (FIG. 3, step S130).

  Subsequently, the pressure detection unit 410 detects the cooling medium pressure P3 in the pressure detection flow path 75A from the pressure sensor 90 (FIG. 3, step S140). Then, the operation control unit 440 determines whether or not the cooling medium pressure P3 is greater than a predetermined threshold value βth (FIG. 3, step S150). When the operation control unit 440 determines that the coolant pressure P3 is equal to or less than the threshold value βth (FIG. 3, step S150: NO), the control circuit 400 determines that the fuel cell 10 is not sufficiently warmed up. Return to processing. The threshold value βth is determined based on a specific design of the fuel cell system 100.

  When the cooling medium pressure P3 is larger than the threshold value βth (FIG. 3, step S150: YES), the operation control unit 440 determines that the fuel cell 10 has been sufficiently warmed up and the flooding of the fuel cell 10 has been eliminated. The flow stop valve 71 and the refrigerant flow stop valve 72 are opened, and the refrigerant circulation pump 55 is driven to start the circulation of the refrigerant in the refrigerant circulation passage 75 (FIG. 3, step S160). Thereafter, the control circuit 400 returns to the process of step S110.

  As described above, in the fuel cell system 100 of the present embodiment, in the flooding suppression process (FIG. 3) described above, in the pressure detection flow path 75A, the coolant flow is stopped (sealed state), and the coolant pressure P3 To detect. In this way, it is possible to accurately know the state of the fuel cell due to the influence of warm-up (power generation). Then, according to the detection result of the cooling medium pressure P3, refrigerant circulation is started in the refrigerant circulation passage 75, and normal power generation is started. In this way, it is possible to start the circulation of the refrigerant in the refrigerant circulation passage 75 or start the normal power generation at an appropriate timing. In other words, the operating state of the fuel cell can be accurately detected by the coolant pressure P3, and appropriate control can be performed accordingly.

A4. Fuel cell system shutdown process:
FIG. 4 is a flowchart of the fuel cell system stop process performed by the fuel cell system 100 of the present embodiment. First, preconditions for this process will be described. Before starting the fuel cell system stop process, the power generation state is normal, the refrigerant stop valve 71, the refrigerant stop valve 72, and the hydrogen cutoff valve 200 are opened, and the purge valve 40 is closed, The refrigerant circulation pump 55, the hydrogen circulation pump 50, and the compressor 30 are driven. Therefore, the pressure detection flow path 75A is in a state where the refrigerant is flowing. In this fuel cell system stop process, the control circuit 400 determines whether or not to perform the scavenging process to prevent the fuel cell system 100 from freezing. When the scavenging process is performed, in order to promote the discharge of residual water, Run while warming up.

  In the fuel cell system stop process, the scavenging determination unit 470 determines whether or not to execute the scavenging process (FIG. 4, step S210). Specifically, the scavenging determination unit 470 reads date data from the date data storage unit 480 and determines whether or not the date represented by the date data corresponds to a cold season (eg, November to March). If it is applicable, it is determined that the scavenging process is to be executed, and if not, it is determined that the scavenging process is not to be executed.

  When the scavenging determination unit 470 determines not to execute the scavenging process (FIG. 4, step S210: NO), the operation control unit 440 drives the compressor 30, the refrigerant circulation pump 55, and the hydrogen circulation pump 50. The fuel cell system 100 is stopped by stopping and disconnecting the connection between the fuel cell 10 and the load 80 and closing the hydrogen cutoff valve 200 (FIG. 4, step S270).

  On the other hand, when the scavenging determination unit 470 determines to execute the scavenging process (FIG. 4, step S210: YES), the refrigerant flow control unit 430 stops driving the refrigerant circulation pump 55 and stops the refrigerant flow. The valve 72 and the refrigerant flow stop valve 71 are closed, and the refrigerant circulation is stopped in the refrigerant circulation passage 75 (FIG. 4, step S220).

  Next, the power generation unit 450 performs a scavenging process while causing the fuel cell 10 to generate power and warming up the fuel cell 10 (FIG. 4, step S230). Specifically, the power generation unit 450 supplies a large excess amount of oxidizing gas to the cathode side of the fuel cell 10 while maintaining the connection between the fuel cell 10 and the load 80 and driving of the compressor 30 and the hydrogen circulation pump 50. The purge valve 40 is opened as appropriate to perform scavenging on the cathode side and the anode side.

  Subsequently, the pressure detection unit 410 detects the cooling medium pressure P4 in the pressure detection flow path 75A from the pressure sensor 90 (FIG. 4, step S240). Then, the operation control unit 440 determines whether or not the cooling medium pressure P4 is greater than a predetermined threshold value γth (FIG. 4, step S250). When the operation control unit 440 determines that the coolant pressure P4 is equal to or lower than the threshold value γth (FIG. 4, step S250: NO), the control circuit 400 determines that the fuel cell 10 is not sufficiently warmed up. Return to processing. The threshold value γth is determined based on the specific design of the fuel cell system 100.

  If the coolant pressure P4 is greater than the threshold value γth (FIG. 4, step S250: YES), the operation control unit 440 determines that the fuel cell 10 is sufficiently warmed up, and scavenging processing for a predetermined time (see step S230). (FIG. 4, step S260: YES), the fuel cell system 100 is stopped (FIG. 4, step S270).

  As described above, the fuel cell system 100 according to the present embodiment has the cooling medium in the state where the refrigerant flow is stopped (sealed state) in the pressure detection flow path 75A in the fuel cell system stop process (FIG. 4) described above. The pressure P4 is detected. In this way, it is possible to accurately know the state of the fuel cell 10 due to the influence of warm-up (power generation). Then, according to the detection result of the cooling medium pressure P4, the scavenging process is terminated and the fuel cell system is stopped. In this way, the scavenging process can be completed, that is, the fuel cell system can be stopped at an appropriate timing. In other words, the operating state of the fuel cell can be accurately detected by the coolant pressure P4, and appropriate control can be performed accordingly.

  In the above embodiment, the refrigerant circulation channel 75 corresponds to the refrigerant circulation channel in the claims, and the refrigerant flow stop valves 71 and 72 and the refrigerant circulation pump 55 correspond to the refrigerant flow stop unit in the claims. The pressure detection unit 410 corresponds to the pressure detection unit in the claims, the operation control unit 440 corresponds to the operation control unit in the claims, and the temperature increase determination unit 420 corresponds to the first temperature increase determination unit or the first in the claims. 2 corresponds to a temperature rise determination unit, the power generation unit 450 corresponds to a warm-up unit or a scavenging processing unit in claims, the scavenging determination unit 470 corresponds to a scavenging determination unit in claims, and the stop control unit 460 This corresponds to the stop control unit in the claims.

B. Variation:
Note that the present invention is not limited to the above-described embodiment, and can be implemented in various modes without departing from the scope of the invention.

B1. Modification 1:
FIG. 5 is a flowchart of a fuel cell system stop process performed by the fuel cell system 100A of the first modification. The fuel cell system stop process in this modification is different from the fuel cell system stop process (FIG. 4) of the above embodiment. This will be specifically described below with reference to FIG. The preconditions are the same as the fuel cell system stop process performed by the fuel cell system 100 of the above embodiment. Further, in the fuel cell system stop process of the first modification, when the scavenging process is executed, the scavenging process (without power generation) is executed after the heat dissipation of the fuel cell 10 is performed. Since the functional blocks of the fuel cell system 100A are the same as those of the fuel cell system 100 of the above embodiment, description thereof is omitted.

  First, in the fuel cell system stop process, the scavenging determination unit 470 determines whether or not to execute the scavenging process (FIG. 5, step S310). Since this determination is the same as the process in step S210 of the fuel cell system stop process (FIG. 4) of the above embodiment, the description is omitted.

  When the scavenging determination unit 470 determines not to execute the scavenging process (FIG. 5, step S310: NO), the operation control unit 440 drives the compressor 30, the refrigerant circulation pump 55, and the hydrogen circulation pump 50. The fuel cell system 100 is stopped by stopping the connection between the fuel cell 10 and the load 80 and closing the hydrogen cutoff valve 200 (FIG. 5, step S360).

  On the other hand, when the scavenging determination unit 470 determines to execute the scavenging process (FIG. 5, Step S310: YES), the stop control unit 460 stops the driving of the compressor 30 and the hydrogen circulation pump 50, and By disconnecting the connection between the fuel cell 10 and the load 80 and closing the hydrogen cutoff valve 200, the power generation of the fuel cell 10 is stopped (FIG. 5, step S320). In this case, the refrigerant is circulated by the refrigerant circulation pump 55 in the refrigerant circulation passage 75.

  Next, the refrigerant stop control unit 430 stops driving the refrigerant circulation pump 55 after a predetermined time has elapsed (especially during this time, the fuel cell 10 is dissipated), and the refrigerant stop valve 72 and the refrigerant stop valve 71. Is closed, and the refrigerant circulation is stopped in the refrigerant circulation passage 75 (FIG. 5, step S330).

  Subsequently, the pressure detection unit 410 detects the cooling medium pressure P5 in the pressure detection flow path 75A from the pressure sensor 90 (FIG. 5, Step S340). Then, the operation control unit 440 determines whether or not the cooling medium pressure P5 is smaller than a predetermined threshold value δth (FIG. 5, Step S340). When the operation control unit 440 determines that the cooling medium pressure P5 is equal to or higher than the threshold value δth (FIG. 5, step S340: NO), the control circuit 400 determines that the heat radiation in the fuel cell 10 is not sufficient, and performs the process of step S340. Return. The threshold value δth is determined based on the specific design of the fuel cell system 100.

  Then, when the cooling medium pressure P5 is smaller than the threshold value δth (FIG. 5, step S340: YES), the operation control unit 440 determines that the heat dissipation in the fuel cell 10 is sufficient, and the scavenging process is performed without power generation. Is executed (FIG. 5, step S350). Specifically, the operation control unit 440 performs the purge while maintaining the drive of the compressor 30 and the hydrogen circulation pump 50 in a state where the connection between the fuel cell 10 and the load 80 is cut off and the hydrogen cutoff valve 200 is closed. The valve 40 is opened, a large excess amount of oxidizing gas is supplied to the cathode side of the fuel cell 10, and scavenging of the cathode side and the anode side is performed.

  Thereafter, the operation control unit 440 performs the scavenging process for a predetermined time, and then stops the fuel cell system 100A (FIG. 5, step S360).

  As described above, the fuel cell system 100A of the present modified example has a cooling medium in a state where the refrigerant flow is stopped (sealed state) in the pressure detection channel 75A in the fuel cell system stop process (FIG. 5) described above. The pressure P5 is detected. In this way, the state of the fuel cell 10 due to heat dissipation can be accurately known. The scavenging process is performed according to the detection result of the cooling medium pressure P5. In this way, the scavenging process can be executed at an appropriate timing with the internal temperature of the fuel cell 10 sufficiently lowered. In other words, the operating state of the fuel cell can be accurately detected by the coolant pressure P5, and appropriate control can be performed accordingly.

  Further, the fuel cell system 100A of the present modification performs the scavenging process after the internal temperature of the fuel cell 10 is sufficiently lowered in the above-described fuel cell system stop process (FIG. 5). If it does in this way, drying of the electrolyte membrane in each cell of fuel cell 10 can be controlled in scavenging processing.

B2: Modification Example 2:
In the fuel cell system 100 of the above-described embodiment, when detecting the coolant pressure in each process (see FIGS. 2, 3, and 4), the refrigerant check valve 71 and the refrigerant stop in the refrigerant circulation passage 75 are detected. Although detection is performed with the valve 72 closed, the present invention is not limited to this, and the refrigerant stop valve 71 and the refrigerant stop valve 72 may be opened. In this case, it is only necessary to detect the coolant pressure in a state in which the refrigerant circulation pump 55 is stopped and the refrigerant flow is stopped in the refrigerant circulation passage 75.

B3: Modification 3:
The fuel cell system 100 according to the above embodiment warms up the fuel cell 10 by causing the power generation unit 450 to generate power in each process (see FIGS. 2, 3, and 4). The invention is not limited to this. For example, the fuel cell 10 may be warmed up by a heater, or the fuel cell 10 may be warmed up by heat generated from the compressor 30 or the hydrogen circulation pump 50.

B4: Modification 4:
In the fuel cell system 100 of the above embodiment or the fuel cell system 100A of the first modification, in the fuel cell system stop process (FIG. 4 or FIG. 5), the scavenging determination unit 470 performs scavenging based on the date represented by the date data. Although it is determined whether or not to perform processing, the present invention is not limited to this. The fuel cell system includes a GPS device (not shown) and cold region data (not shown) indicating cold region information, and the scavenging determination unit 470 acquires position data acquired from the GPS device, It may be determined whether or not the scavenging process is performed in consideration of the position represented by the data and the cold region information represented by the cold region data. In this case, the date represented by the date data may be considered. The fuel cell system also includes a temperature sensor (not shown) for detecting the external temperature of the fuel cell system. When the fuel cell system is activated, the external temperature is detected from the temperature sensor and stored as temperature data. Keep it. And scavenging judgment part 470 acquires temperature data, examines whether the temperature which the temperature data represents is lower than a predetermined threshold, and judges that scavenging processing is performed when the temperature is lower than the threshold. You may do it.

B5. Modification 5:
In the fuel cell system 100 of the above embodiment, the pressure sensor 90 is provided between the fuel cell 10 and the refrigerant flow stop valve 72 in the pressure detection flow path 75A, but the present invention is not limited to this. Absent. For example, the pressure sensor 90 may be provided in the refrigerant circulation channel 75A between the fuel cell cooling channel 17 or between the fuel cell 10 and the refrigerant flow stop valve 71. Even if it does in this way, there can exist an effect similar to the said Example.

B6. Modification 6:
In the fuel cell system 100 of the above embodiment, in each process (FIGS. 2, 3, and 4), the operation control unit 440 performs various controls based on the coolant pressure detected in the refrigerant circulation passage 75. However, the present invention is not limited to this. For example, the fuel cell system 100 includes correlation data (correlation formula, correlation table, etc.) that replaces the coolant pressure in the refrigerant circulation passage 75 with temperature, and the operation control unit 440 determines the temperature obtained from the detected coolant pressure. The various controls described above may be performed based on the above. Even if it does in this way, there can exist an effect similar to the said Example.

B7. Modification 7:
In the above-described embodiment, each part of the control circuit 400 may be configured by hardware instead of software, or may be configured by hardware. You may make it do.

1 is a block diagram showing a configuration of a fuel cell system 100 as an embodiment of the present invention. It is a flowchart of the fuel cell system starting process which the fuel cell system 100 of the said Example performs. It is a flowchart of the flooding suppression process which the fuel cell system 100 of the said Example performs. It is a flowchart of the fuel cell system stop process which the fuel cell system 100 of the said Example performs. It is a flowchart of the fuel cell system stop process which the fuel cell system 100A of the said modification 1 performs.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Fuel cell 20 ... Hydrogen tank 30 ... Compressor 35 ... Cathode flow path 40 ... Purge valve 50 ... Hydrogen circulation pump 55 ... Refrigerant circulation pump 70 ... Radiator 71 ... refrigerant stop valve 72 ... refrigerant stop valve 75 ... refrigerant circulation passage 75A ... pressure detection passage 80 ... load 90 ... pressure sensor 95 ... voltage sensor 100. .. Fuel cell system 100A ... Fuel cell system 200 ... Hydrogen shut-off valve 400 ... Control circuit 410 ... Pressure detection unit 420 ... Temperature rise determination unit 430 ... Refrigerant flow control unit 440 ... Operation control unit 450 ... Warm-up unit 460 ... Stop control unit 470 ... Scurge judgment unit 480 ... Date data storage unit

Claims (12)

A fuel cell system comprising a fuel cell,
A cooling medium flow path through which the cooling medium for cooling the fuel cell passes through the inside of the fuel cell;
A coolant stop portion for stopping the flow of the cooling medium in the cooling medium flow path;
In the cooling medium flow path, the pressure of the cooling medium is detected in the fuel cell or in a sealed space between the fuel cell and the refrigerant flow stopping portion in a state where the flow of the cooling medium is stopped. A pressure detector;
An operation control unit that performs operation control of the fuel cell according to the pressure detected by the pressure detection unit;
A fuel cell system comprising: The fuel cell system according to claim 1, wherein
A warm-up part for warming up the fuel cell;
The pressure detector is
The cooling medium includes a first detection unit that detects a pressure of the cooling medium that is raised by being warmed up by the warming-up unit in a state where the flow of the cooling medium is stopped by the refrigerant flow-stopping unit. A fuel cell system. The fuel cell system according to claim 2, wherein
The operation controller is
When the pressure of the cooling medium detected by the first detection unit is larger than a second threshold value, the fuel cell system starts to flow the cooling medium toward the fuel cell in the cooling medium flow path. . The fuel cell system according to claim 2 or 3,
A first temperature increase determination unit that detects the pressure of the cooling medium at the time of startup of the fuel cell system and determines that the temperature increase of the fuel cell is necessary when the pressure is equal to or lower than a first threshold;
The warm-up part is
The fuel cell system, wherein when the second temperature increase determination unit determines that the temperature of the fuel cell needs to be increased, the fuel cell is warmed up. The fuel cell system according to any one of claims 2 to 4,
A second temperature increase determination unit that determines that the temperature of the fuel cell needs to be increased when flooding occurs in the fuel cell;
The fuel cell system, wherein when the second temperature increase determination unit determines that the temperature of the fuel cell needs to be increased, the fuel cell is warmed up. The fuel cell system according to claim 2, wherein
A fuel cell system, comprising: a scavenging process unit that performs a scavenging process when the warm-up unit warms the fuel cell when the fuel cell system is stopped. The fuel cell system according to claim 6, wherein
The operation controller is
The fuel cell system, wherein the fuel cell system is stopped when a pressure of the cooling medium detected by the first detection unit is larger than a third threshold value. The fuel cell system according to claim 6 or 7,
A scavenging determination unit that determines whether to perform the scavenging process when the fuel cell system is stopped,
The scavenging processing unit
When the scavenging determination unit determines to perform the scavenging process, the fuel cell system performs the scavenging process while generating power in the fuel cell. The fuel cell system according to claim 1, wherein
A scavenging determination unit for determining whether to perform the scavenging process of the fuel cell;
When the scavenging determination unit determines that the scavenging process of the fuel cell is necessary, the scavenging determination unit includes a stop control unit that stops power generation of the fuel cell,
The pressure detector is
A second detection unit for detecting the pressure of the cooling medium after the stop control unit stops power generation of the fuel cell and in a state where the flow of the cooling medium is stopped by the refrigerant flow stop unit; Prepared,
The operation controller is
A scavenging process that does not involve power generation is performed when the pressure of the cooling medium detected by the second detection unit is smaller than a fourth threshold value. The fuel cell system according to any one of claims 2 to 8,
The warm-up part is
A fuel cell system that warms up the fuel cell by causing the fuel cell to generate power. The fuel cell system according to claim 8 or 9, wherein
The scavenging determination unit
A fuel cell system that determines whether or not to perform a scavenging process of the fuel cell based on date data or at least one of temperature data representing an external temperature at the time of startup of the fuel cell system. A control method of a fuel cell system comprising a coolant flow path that passes through a fuel cell and flows a coolant for cooling the fuel cell,
Stopping the flow of the cooling medium in the cooling medium flow path;
In the cooling medium flow path, the pressure of the cooling medium is detected in the fuel cell or in a sealed space between the fuel cell and the refrigerant flow stopping portion in a state where the flow of the cooling medium is stopped. Process,
A step of controlling the operation of the fuel cell according to the detected pressure;
A control method for a fuel cell system, comprising:

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