JP2011216307A - Starting method of fuel cell system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a starting method of a fuel cell system which can perform excellently operation under a low humidification condition while suppressing performance deterioration.SOLUTION: The starting method of the fuel cell system S having a solid polymer fuel battery cell 3 includes: an anode 3a to be supplied with a fuel gas; a cathode 3b to be supplied with an oxygen-contained gas; and an electrolyte 3c installed between the anode 3a and the cathode 3b, and has a humidification condition verification process to verify the humidification condition of the solid polymer fuel battery cell 3 when system starting and a humidification condition adjustment process when starting which includes both of an adjustment in a humidification increase direction of the humidification condition of the solid polymer fuel battery cell 3 when system starting after the humidification condition verification process and an adjustment in a humidification decrease direction, based on the verification result of the humidification condition verification process.

Description

  The present invention relates to a method for starting a fuel cell system including a polymer electrolyte fuel cell having an anode to which a fuel gas is supplied, a cathode to which an oxygen-containing gas is supplied, and an electrolyte provided between the anode and the cathode. About.

  Since the polymer electrolyte fuel cell can generate power by wetting the electrolyte (solid polymer membrane) and the electrode parts (anode and cathode) that constitute the cell, the polymer electrolyte fuel cell uses the gas supplied to the polymer electrolyte fuel cell. The operation is performed by humidifying the electrolyte and the electrode part, for example, mixing water vapor. In stationary applications where long-term durability is required, operation is generally performed under saturated humidification conditions where the battery temperature and the dew point of the gas supplied to the polymer electrolyte fuel cell are substantially the same from the viewpoint of suppressing deterioration.

On the other hand, the humidification function in the fuel cell system (for example, a bubbler device that includes water vapor in the gas supplied to the anode and the cathode) is simplified or eliminated, thereby reducing the cost of the system. It has been broken. For example, as described in Non-Patent Document 1, development is underway to suppress battery deterioration even under low humidification conditions that are not saturated humidification conditions.
Under such low humidification conditions, how efficiently the water generated by power generation can be efficiently used for wetting the battery is important for drawing out power generation performance. For this reason, as described in Non-Patent Document 2, optimization of battery constituent members is underway.

Eiji Endoh, ECS Transactions, 16 (2), 1229 (2008) Nishikawa, Nakamura, Matsuyama, Satoshi, Proceedings of the 15th Fuel Cell Symposium, 123 (2008)

  However, under low humidification conditions (for example, a condition where at least one dew point of the gas supplied to the anode and the cathode is 10 ° C. or more lower than the temperature of the polymer electrolyte fuel cell) When operating the fuel cell while keeping the inside wet, there is a possibility that the wet state inside the cell may change due to changes in operating conditions and environment. Deterioration of the battery is promoted when the wetness is insufficient, and conversely, when the wetness is excessive, dew condensation occurs and the performance may be deteriorated due to water clogging. For example, when the amount of water present in the polymer electrolyte fuel cell becomes less than the required amount (that is, when water becomes insufficient), the conductivity of hydrogen ions in the electrolyte deteriorates (that is, the resistance increases). Alternatively, when the amount of water present in the polymer electrolyte fuel cell increases more than necessary (that is, when the water becomes excessive), the pores of the gas diffusion layers constituting the anode and the cathode are blocked with water. Gas diffusion is hindered. As a result, problems such as a decrease in the output voltage of the polymer electrolyte fuel cell and deterioration of the polymer electrolyte fuel cell may occur.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a method for starting a fuel cell system that can satisfactorily operate under low humidification conditions while suppressing a decrease in performance.

  Activation of a fuel cell system comprising a polymer electrolyte fuel cell having an anode supplied with a fuel gas, a cathode supplied with an oxygen-containing gas, and an electrolyte provided between the anode and the cathode according to the present invention The characteristic configuration of the method includes a humidification state verification step for verifying a humidification state of the polymer electrolyte fuel cell at the time of system startup, and a system after the humidification state verification step based on the verification result of the humidification state verification step A startup humidification state adjustment step including adjusting the humidification state of the polymer electrolyte fuel cell at startup in a humidification increasing direction and in a humidification decreasing direction.

According to the above characteristic configuration, when the fuel cell system is intermittently operated, even if the humidification state of the polymer electrolyte fuel cell changes, the humidification state is verified in the humidification state verification step. Based on the verification result of the process, in the humidification state adjustment process at startup after the humidification state verification process, the humidification state of the polymer electrolyte fuel cell can be adjusted to either the humidification increasing direction or the humidification decreasing direction. In other words, the humidification state of the polymer electrolyte fuel cell is appropriately adjusted at the time of system start-up by the humidification state verification step and the humidification state adjustment step at start-up, so that the performance of the polymer electrolyte fuel cell is continuously improved. Maintained. In particular, a special humidifying function for supplying moisture to the polymer electrolyte fuel cell (for example, a bubbler device that includes water vapor in the gas supplied to the anode and the cathode) is simplified or provided. Even if the fuel cell system is operated under low humidification conditions such that the polymer electrolyte fuel cell is humidified with water mainly generated during power generation in the polymer electrolyte fuel cell. The humidified state of the polymer electrolyte fuel cell can be appropriately adjusted by the humidified state verification step and the startup humidified state adjusting step.
Therefore, it is possible to provide a fuel cell system start-up method that can satisfactorily operate under low humidification conditions while suppressing performance degradation.

  Here, the humidification state verification step monitors the output voltage of the polymer electrolyte fuel cell, and based on the output voltage, the polymer electrolyte fuel cell is in a water shortage state, an excessive water state, and an appropriate It is preferable that it is a step of verifying which of the states is in the state.

If the humidification state of the polymer electrolyte fuel cell is in a water-deficient state at the time of starting the system in which the humidification state verification process is performed, the output voltage of the polymer electrolyte fuel cell is higher than the output voltage when the humidification state is appropriate Is also observed. In addition, if the humidification state of the polymer electrolyte fuel cell is excessive, the phenomenon that the output voltage of the polymer electrolyte fuel cell becomes unstable compared to when the humidification state is appropriate is recognized. It is done. Here, “destabilize” means that the output voltage varies.
According to this configuration, based on the change state of the output voltage of the polymer electrolyte fuel cell at the time of starting the system, the state of the polymer electrolyte fuel cell is a water shortage state, an excessive water state, or an appropriate state. It is possible to verify whether the state is.

  Therefore, in the humidification state verification step, when the output voltage value of the polymer electrolyte fuel cell falls below the normal output voltage value range expected in the appropriate state, it is determined that the water shortage state. , When the stability of the output voltage of the polymer electrolyte fuel cell exceeds the degree of stability of the output voltage expected in the appropriate state, it is determined that the water is excessive, and the water shortage state And when it is neither of the water excess states, it is preferable that the configuration is determined as the appropriate state.

  According to this configuration, it is possible to appropriately determine whether the state of the polymer electrolyte fuel cell at the time of starting the system is in a water shortage state, an excessive water state, or an appropriate state.

  Further, in the startup humidification state adjustment step, if the verification result that the humidification state of the polymer electrolyte fuel cell is the water-deficient state in the humidification state verification step is obtained, the polymer electrolyte fuel cell The fuel gas supplied to the polymer electrolyte fuel cell is reduced by lowering the power generation start temperature set to define the conditions for starting the power generation from the power generation start temperature in the proper state. It is preferable that the power generation be started in a state in which the flow rate of at least one of the oxygen-containing gas is reduced below the flow rate in the proper state.

In the humidification state verification step, when a verification result is obtained that the humidification state of the polymer electrolyte fuel cell is a water shortage state, in the startup humidification state adjustment step executed after the humidification state verification step, the solid What is necessary is just to transfer the humidification state of a polymer fuel cell to the humidification increasing direction (direction to make it wet more).
According to this configuration, the power generation start temperature that is set to define the conditions under which the polymer electrolyte fuel cell starts power generation is set to start power generation when the polymer electrolyte fuel cell is in an appropriate state. By reducing the temperature below the temperature, the amount of generated water evaporated at the time of starting the system can be reduced, and the humidified state of the polymer electrolyte fuel cell can be shifted in the direction of increasing humidification. Alternatively, the flow rate of at least one of the fuel gas and the oxygen-containing gas supplied to the polymer electrolyte fuel cell is reduced from the flow rate when the polymer electrolyte fuel cell is in an appropriate state By starting power generation at, the amount of generated water brought out of the polymer electrolyte fuel cell by these gases when the system starts up is reduced, and the humidification state of the polymer electrolyte fuel cell is increased. Can be moved in the direction. Therefore, it can be adjusted to increase the humidified state of the polymer electrolyte fuel cell at the time of starting the system, and can be brought closer to an appropriate state.

  Further, in the startup humidification state adjustment step, if the verification result that the humidification state of the polymer electrolyte fuel cell is the excessive water state is obtained in the humidification state verification step, the solid polymer fuel cell is obtained. The fuel to be supplied to the polymer electrolyte fuel cell, or a power generation start temperature set to define a condition for the cell to start power generation is set higher than the power generation start temperature when the cell is in the appropriate state. It is preferable that the power generation be started in a state where the flow rate of at least one of the gas and the oxygen-containing gas is increased from the flow rate in the proper state.

In the humidification state verification step, when the verification result that the humidification state of the polymer electrolyte fuel cell is an excessive water state is obtained, in the startup humidification state adjustment step executed after the humidification state verification step, What is necessary is just to transfer the humidification state of a polymer electrolyte fuel cell to a humidification decreasing direction (direction to dry more).
According to this configuration, the power generation start temperature that is set to define the conditions under which the polymer electrolyte fuel cell starts power generation is set to start power generation when the polymer electrolyte fuel cell is in an appropriate state. By raising the temperature above the temperature, it is possible to increase the evaporation amount of the generated water at the time of starting the system and shift the humidified state of the polymer electrolyte fuel cell toward the humidification decreasing direction. Alternatively, the flow rate of at least one of the fuel gas and oxygen-containing gas supplied to the polymer electrolyte fuel cell is increased from the flow rate when the polymer electrolyte fuel cell is in an appropriate state By starting power generation at, the amount of generated water brought out of the polymer electrolyte fuel cell by these gases when the system starts up is increased, and the humidification state of the polymer electrolyte fuel cell is reduced. Can be moved in the direction. Therefore, it can be adjusted to reduce the humidification state of the polymer electrolyte fuel cell at the time of starting the system, and can be brought closer to an appropriate state.

  Activation of a fuel cell system comprising a polymer electrolyte fuel cell having an anode supplied with a fuel gas, a cathode supplied with an oxygen-containing gas, and an electrolyte provided between the anode and the cathode according to the present invention Another characteristic configuration of the method is that the power generation start temperature set to define the conditions under which the polymer electrolyte fuel cell starts power generation is set to an appropriate humidified state. Lower than the power generation start temperature in the maintained proper state, or the flow rate of at least one of the fuel gas and the oxygen-containing gas supplied to the polymer electrolyte fuel cell in the proper state It is in the point which has a humidification state increase process at the time of starting which performs electric power generation in the state decreased rather than the flow volume in a certain case.

In a fuel cell system operated under low humidification conditions, the dew point of at least one of the fuel gas supplied to the anode and the oxygen-containing gas supplied to the cathode is set lower than the temperature of the polymer electrolyte fuel cell. Therefore, for example, as compared with a fuel cell system operated under saturated humidification conditions, the humidified state of the polymer electrolyte fuel cell tends to be in a water-deficient state.
According to this characteristic configuration, in the humidification state increase process at the time of starting, the power generation start temperature set in order to define the conditions under which the polymer electrolyte fuel cell starts power generation is set to the state of the polymer electrolyte fuel cell. Is lower than the power generation start temperature when the battery is in an appropriate state, so that the amount of water generated during system startup is reduced, and the humidification state of the polymer electrolyte fuel cell is increased (more wetted) ). Alternatively, the flow rate of at least one of the fuel gas and the oxygen-containing gas supplied to the polymer electrolyte fuel cell is reduced from the flow rate when the polymer electrolyte fuel cell is in an appropriate state By starting power generation at, the amount of generated water brought out of the polymer electrolyte fuel cell by these gases when the system starts up is reduced, and the humidification state of the polymer electrolyte fuel cell is increased. Can be moved in the direction. Therefore, in general, the humidified state of the polymer electrolyte fuel cell, which is likely to be in a water-deficient state when operated under a low humidification condition, can be shifted closer to an appropriate state when the system is started up in the direction of increasing humidification.
Therefore, it is possible to provide a fuel cell system start-up method that can satisfactorily operate under low humidification conditions while suppressing performance degradation.

  A polymer electrolyte fuel cell having an anode to which a fuel gas is supplied, a cathode to which an oxygen-containing gas is supplied, and an electrolyte provided between the anode and the cathode, and a cooling water circulation path according to the present invention And cooling means for cooling the polymer electrolyte fuel cell with the cooling water that is further characterized in that the fuel cell system start-up method comprises a flow rate of the cooling water circulating through the cooling water circulation path, A starting humidification state increasing step of starting power generation in a state where the solid polymer fuel cell is in an appropriate state in which the solid polymer fuel cell is maintained in an appropriate humidification state is increased from the flow rate.

According to this characteristic configuration, the flow rate of the cooling water circulating in the cooling water circulation path in the startup humidification state increasing step is the flow rate when the polymer electrolyte fuel cell is in an appropriate state maintained in an appropriate humidification state. By starting the power generation in a state where it is further increased, the temperature rise of the polymer electrolyte fuel cell at the time of starting the system can be made slower. Thereby, the evaporation amount of the generated water at the time of starting the system can be reduced, and the humidified state of the polymer electrolyte fuel cell can be shifted to the humidification increasing direction. Therefore, in general, the humidified state of the polymer electrolyte fuel cell, which is likely to be in a water-deficient state when operated under a low humidification condition, can be shifted closer to an appropriate state when the system is started up in the direction of increasing humidification.
Therefore, it is possible to provide a fuel cell system start-up method that can satisfactorily operate under low humidification conditions while suppressing performance degradation.

It is a figure which shows the structure of a fuel cell system. It is a figure which shows typically the operating state of a fuel cell system. It is explanatory drawing of standard system starting control. It is explanatory drawing of standard system stop control. It is a graph which shows the change state of the output voltage of a polymer electrolyte fuel cell at the time of starting of a fuel cell system. It is a figure which shows the aspect of the humidification state adjustment process at the time of starting which concerns on 1st embodiment. It is a figure which shows the aspect of the humidification state adjustment process at the time of a stop which concerns on 1st embodiment. It is a figure which shows the aspect of the humidification state adjustment process at the time of starting which concerns on 2nd embodiment. It is a figure which shows the aspect of the humidification state adjustment process at the time of a stop which concerns on 2nd embodiment.

1. First Embodiment A first embodiment of a starting method and a stopping method of a fuel cell system S according to the present invention will be described with reference to the drawings. In the fuel cell system S according to the present embodiment, the humidification state verification step V (see FIG. 2) for verifying the humidification state of the polymer electrolyte fuel cell 3 at the time of system startup, and the verification results of the humidification state verification step V Based on the verification results of the humidification state adjustment step A at startup and the humidification state verification step V for adjusting the humidification state of the polymer electrolyte fuel cell 3 at the time of system startup after the humidification state verification step V Then, when the system is stopped after the humidification state verification step V, the stop humidification state adjustment step B for adjusting the humidification state of the polymer electrolyte fuel cell 3 is performed. The startup humidification state adjustment step A and the stop humidification state adjustment step B include both adjusting the humidification state of the polymer electrolyte fuel cell 3 in the humidification increasing direction and in the humidification decreasing direction, respectively. The control unit 12 executes the humidification state verification step V and the startup humidification state adjustment step A every time the fuel cell system S that is intermittently operated, for example, is started up, and the stop humidification state adjustment step B is, for example, intermittently operated. It is executed every time when the fuel cell system S is stopped. Details will be described below.

1-1. 1 is a diagram illustrating the configuration of a fuel cell system S. As shown in FIG. The fuel cell system S is a solid having an anode 3a to which fuel gas is supplied, a cathode 3b to which oxygen-containing gas is supplied, and an electrolyte (solid polymer membrane) 3c provided between the anode 3a and the cathode 3b. A polymer fuel cell 3 is provided. Usually, a plurality of polymer electrolyte fuel cells 3 are connected in series to form a cell stack.

  In the present embodiment, the fuel gas supplied to the anode 3 a is generated by the fuel gas supply unit 1. The fuel gas supply unit 1 is an apparatus that generates a fuel gas mainly composed of hydrogen by steam reforming a raw fuel such as hydrocarbon (for example, methane) or alcohol. Although not shown in FIG. 1, in order to perform steam reforming, steam is added to the raw fuel. The flow rate of the fuel gas supplied from the fuel gas supply unit 1 to the anode 3 a varies according to the flow rate of the raw fuel supplied to the fuel gas supply unit 1. That is, the flow rate of the fuel gas supplied to the anode 3 a can be adjusted by the flow rate of the raw fuel supplied to the fuel gas supply unit 1. In the present embodiment, the control unit 12 adjusts the flow rate of the raw fuel supplied to the fuel gas supply unit 1 by controlling the operation of a flow rate adjusting means (not shown) such as a pump.

  In the present embodiment, the oxygen-containing gas supplied to the cathode 3b is air. The oxygen-containing gas supply unit 2 is a pump that can send air to the cathode 3b. In the present embodiment, the control unit 12 adjusts the flow rate of the oxygen-containing gas (air) supplied to the cathode 3 b by controlling the operation of the oxygen-containing gas supply unit 2.

  In the solid polymer fuel cell 3, during normal operation, hydrogen (fuel gas) supplied to the anode 3 a becomes hydrogen ions and moves to the cathode 3 b through the electrolyte 3 c, and in oxygen-containing gas (air). Reacts with oxygen to produce water. At this time, a current flows through a load (the power conversion unit 8 in FIG. 1) in the electric circuit connecting the anode 3a and the cathode 3b. The conductivity of hydrogen ions in the electrolyte 3c is higher when water is present in the electrolyte 3c. The fuel cell system S of the present embodiment is not provided with a special mechanism for humidifying the polymer electrolyte fuel cell 3 (except for the humidification for the steam reforming). Specifically, the fuel cell system S of the present embodiment is not provided with a special device (for example, a bubbler device) that includes water vapor in the gas supplied to the anode and the cathode.

  In the fuel cell system S according to this embodiment, the dew point of the fuel gas (hydrogen) after steam reforming is about 30 to 40 ° C. As described above, the fuel gas (hydrogen) is thereafter supplied to the polymer electrolyte fuel cell 3 without being particularly humidified. On the other hand, during normal operation, the temperature of the polymer electrolyte fuel cell 3 is maintained at about 70 to 80 ° C. Therefore, the fuel cell system S according to the present embodiment is normally operated under low humidification conditions. In the present embodiment, the low humidification condition is a condition in which the dew point of at least one of the gases supplied to the anode 3 a and the cathode 3 b is 10 ° C. or lower than the temperature of the polymer electrolyte fuel cell 3. Under such low humidification conditions, water (generated water) generated at the cathode 3b during normal operation (power generation) becomes the main water for humidifying the polymer electrolyte fuel cell 3.

  The DC output of the polymer electrolyte fuel cell 3 is converted into appropriate power by the power converter 8 and then supplied to the load 11. The output voltage of the polymer electrolyte fuel cell 3 is measured by a voltmeter 9, and the output current of the polymer electrolyte fuel cell 3 is measured by an ammeter 10.

The controller 12 can adjust the temperature of the polymer electrolyte fuel cell 3. In the present embodiment, the fuel cell system S includes a cooling means C that can cool the polymer electrolyte fuel cell 3.
The cooling means C includes a hot water storage unit 6 that stores hot water as cooling water, and a heat exchange unit 4 that performs heat exchange between the heat generated in the polymer electrolyte fuel cell 3 and hot water (cooling water). The low-temperature hot water (cooling water) stored in the hot water storage section 6 circulates so that it flows through the heat exchange section 4 and returns to the hot water storage section 6, and the flow rate of hot water in the cooling water circulation path 13 is And a pump 7 to be adjusted. When the flow rate of hot water in the cooling water circulation path 13 is increased, cooling of the polymer electrolyte fuel cell 3 is promoted, and the temperature of the polymer electrolyte fuel cell 3 is lowered. Conversely, when the flow rate of hot water in the cooling water circulation path 13 decreases, the cooling of the polymer electrolyte fuel cell 3 is suppressed and the temperature of the polymer electrolyte fuel cell 3 rises. The control unit 12 can control the operation of the pump 7 to adjust the flow rate of hot water in the cooling water circulation path 13. That is, the control unit 12 can adjust the temperature of the polymer electrolyte fuel cell 3 by controlling the operation of the pump 7.

  Further, the fuel cell system S includes a heating means H that can heat the polymer electrolyte fuel cell 3. The heating means H is provided so as to be able to transfer heat to the polymer electrolyte fuel cell 3. The heating means H is, for example, a resistance heating type heater 5. When the fuel cell system S is activated, the controller 12 energizes the heater 5 to increase the temperature of the polymer electrolyte fuel cell 3. In the present embodiment, the heating means H is used only when the system is started, and is not used during normal operation.

1-2. Operation Control of Fuel Cell System The fuel cell system S includes a control unit 12 for controlling the operation of each unit of the fuel cell system S. For example, the control unit 12 controls the operating state of the entire fuel cell system S. FIG. 2 is a diagram schematically showing the operating state of the fuel cell system S. As shown in FIG. As shown in this figure, the fuel cell system S repeats the operation state and the stop state intermittently. Then, when the fuel cell system S is in the operating state, first, the system activation control is executed, and then the system activation control is switched to the normal operation control. Further, when the fuel cell system S is in a stopped state, the normal operation control is first switched to the system stop control, and after the system stop control is executed, the fuel cell system S is completely stopped.

Here, the contents of the system start control and the system stop control will be briefly described. FIG. 3 is an explanatory diagram of system activation control under standard conditions.
As shown in this figure, in the system start-up control, first, the control unit 12 supplies the fuel gas and the oxygen-containing gas to the polymer electrolyte fuel cell 3 at a preset standard flow rate Fs, and the heater. 5 is increased to gradually increase the temperature of the polymer electrolyte fuel cell 3. When the temperature of the polymer electrolyte fuel cell 3 reaches a standard power generation start temperature Ts set in advance as a condition for the polymer electrolyte fuel cell 3 to start power generation, the control unit 12 starts power generation. At the same time, the output current (power generation output) taken out from the polymer electrolyte fuel cell 3 and supplied to the load unit 11 is gradually increased. When the output current eventually reaches the preset standard output current Is, the control unit 12 gradually increases the supply flow rates of the fuel gas and the oxygen-containing gas to the polymer electrolyte fuel cell 3 from the standard flow rate Fs. Here, the “standard flow rate Fs” is used as a concept that comprehensively represents the standard flow rate for the fuel gas and the standard flow rate for the oxygen-containing gas (hereinafter the same).

  When the system startup control ends, the operation is switched to normal operation control. In the present embodiment, as the normal operation control, rated output control for controlling the fuel cell system S so as to generate power in a state where energy efficiency is maximized is performed. In this example, such rated output control is also maximum output control for controlling the fuel cell system S so that power generation is performed in a state where the power generation output is maximized. During the normal operation control, the supply flow rates of the fuel gas and the oxygen-containing gas to the polymer electrolyte fuel cell 3 are the normal operation flow rate Fr (see FIG. 4). When the rated output control is performed as in this example, the standard flow rate Fr during operation is a flow rate that only outputs the rated power. The temperature of the polymer electrolyte fuel cell 3 is a standard operating temperature Tr. Here, the “operational standard flow rate Fr” is used as a concept that comprehensively represents the standard flow rate for the fuel gas and the standard flow rate for the oxygen-containing gas (the same applies hereinafter).

  FIG. 4 is an explanatory diagram of system stop control under standard conditions. As shown in this figure, in the system stop control, first, the control unit 12 gradually decreases the supply flow rate of the fuel gas and the oxygen-containing gas to the polymer electrolyte fuel cell 3 from the standard flow rate Fr during operation, The output current (power generation output) taken out from the polymer fuel cell 3 and supplied to the load unit 11 is gradually reduced. At this time, the temperature of the polymer electrolyte fuel cell 3 is also gradually lowered. When the output current (power generation output) eventually reaches a preset stop-time standard current Ir, the control unit 12 maintains the supply flow rates of the fuel gas and the oxygen-containing gas to the polymer electrolyte fuel cell 3 constant. Further, when the output current (power generation output) reaches zero and power generation is completely stopped, the control unit 12 sets the supply flow rates of the fuel gas and the oxygen-containing gas to zero.

1-3. As described above, in the fuel cell system S, the polymer electrolyte fuel cell 3 itself is humidified with water generated by power generation in the polymer electrolyte fuel cell 3. Do. For this purpose, the produced water needs to be effectively used in the polymer electrolyte fuel cell 3. Therefore, it is preferable to prevent the produced water from being taken out of the polymer electrolyte fuel cell 3. Inside the polymer electrolyte fuel cell 3, the generated water generated at the cathode 3b permeates not only in the vicinity of the cathode 3b but also into the electrolyte 3c and the anode 3a. When the fuel cell system S is in an operating state, the generated water is always in contact with the fuel gas at the anode 3a and is always in contact with air at the cathode 3b. As a result, the generated water existing in the vicinity of the anode 3a is taken out of the polymer electrolyte fuel cell 3 by the gas discharged from the anode 3a, and the gas discharged from the cathode 3b The produced water present in the vicinity is taken out of the polymer electrolyte fuel cell 3.

  The control unit 12 can shift the humidified state of the polymer electrolyte fuel cell 3 to a humidification decreasing direction (a direction of further drying). For example, the control unit 12 controls the operation of the cooling means C to raise the temperature of the polymer electrolyte fuel cell 3, thereby increasing the evaporation amount of the generated water, so that the polymer electrolyte fuel cell 3 It is possible to shift the humidified state in the direction of decreasing humidification. Alternatively, the control unit 12 controls the operation of at least one of the fuel gas supply unit 1 and the oxygen-containing gas supply unit 2 and supplies at least one of the fuel gas and the oxygen-containing gas supplied to the polymer electrolyte fuel cell 3. By increasing one of the flow rates, the amount of generated water brought out of the polymer electrolyte fuel cell 3 by those gases is increased, and the humidification state of the polymer electrolyte fuel cell 3 is humidified. It can be shifted in a decreasing direction.

  Or the control part 12 can transfer the humidification state of the polymer electrolyte fuel cell 3 to a humidification increasing direction (direction to make it wet more). For example, the control unit 12 controls the operation of the cooling means C to lower the temperature of the polymer electrolyte fuel cell 3 to reduce the evaporation amount of generated water, so that the polymer electrolyte fuel cell 3 The humidified state can be shifted in the direction of increasing humidification. Alternatively, the control unit 12 controls the operation of at least one of the fuel gas supply unit 1 and the oxygen-containing gas supply unit 2 and supplies at least one of the fuel gas and the oxygen-containing gas supplied to the polymer electrolyte fuel cell 3. By reducing one of the flow rates, the amount of generated water brought out of the polymer electrolyte fuel cell 3 by these gases is reduced, and the humidification state of the polymer electrolyte fuel cell 3 is humidified. It can be shifted in the increasing direction.

1-4. Humidification state verification process The humidification state verification process V monitors the output voltage of the polymer electrolyte fuel cell 3 at the time of starting the system, and based on the output voltage, the polymer electrolyte fuel cell 3 is in a water-deficient state, water This is a step of verifying whether the state is an excessive state or an appropriate state. For example, when the amount of water present in the polymer electrolyte fuel cell 3 is increased and the water is excessive, the pores of the gas diffusion layers constituting the anode 3a and the cathode 3b are blocked with water during normal operation. The gas diffusion is hindered. In addition, when the amount of water present in the polymer electrolyte fuel cell 3 is reduced and the water is insufficient, the conductivity of hydrogen ions in the electrolyte 3c is deteriorated (that is, the resistance is increased). As a result, problems such as a decrease in the output voltage of the polymer electrolyte fuel cell 3 and deterioration of the polymer electrolyte fuel cell 3 may occur.

  Therefore, in this humidified state verification step V, the humidified state of the polymer electrolyte fuel cell 3 is verified using the output voltage of the polymer electrolyte fuel cell 3 at the time of system startup as an index, and the polymer electrolyte fuel cell It is determined whether the humidified state of the cell 3 is in an appropriate state, in an excessive water state, or in a water shortage state. The “excessive water state” is a state in which the amount of water present in the polymer electrolyte fuel cell 3 has increased more than necessary, and the “water shortage state” requires the water present in the polymer electrolyte fuel cell 3. The state is less than the amount. In addition, the “appropriate state” is a state where the polymer electrolyte fuel cell 3 has a necessary amount of water between the excessive water state and the insufficient water state, and there is almost no excess or insufficient.

  In the present embodiment, in the humidified state verification step V, the humidified state of the polymer electrolyte fuel cell 3 is verified using the output voltage value and stability of the polymer electrolyte fuel cell 3 as indices. In this example, in the humidification state verification step V, the degree of decrease of the output voltage value of the polymer electrolyte fuel cell 3 with respect to the output voltage value expected in the appropriate state, and the output voltage of the polymer electrolyte fuel cell 3 The degree of instability with respect to the stability of the output voltage expected in the proper state is monitored. And as shown in FIG. 5, when the fall degree of an output voltage value is large, it determines with a water shortage state, and when the instability degree of an output voltage is large, it determines with an excessive water state. That is, when the output voltage value of the polymer electrolyte fuel cell 3 is lower than the normal output voltage value range expected in the proper state, it is determined that the water is insufficient. More specifically, when the output voltage value of the polymer electrolyte fuel cell 3 is reduced to, for example, 96% or less of the output voltage value expected in an appropriate state, it is determined that the water is insufficient. On the other hand, when the stability of the output voltage of the polymer electrolyte fuel cell 3 exceeds the degree of stability of the output voltage expected in an appropriate state, it is determined that the water is excessive. More specifically, the fluctuation width per unit time of the output voltage value of the polymer electrolyte fuel cell 3 is, for example, five times or more the fluctuation width per unit time of the output voltage value expected in an appropriate state. In the case of excessive water. Note that the above-described determination criterion is merely an example, and the setting can be appropriately changed according to the characteristics of the polymer electrolyte fuel cell 3. Moreover, when neither a water shortage state nor an excessive water state is determined, it is determined as an appropriate state. That is, when the output voltage value maintains stability and hardly decreases, it is determined as an appropriate state.

  In the present embodiment, in order to suppress the deterioration of the polymer electrolyte fuel cell 3, a first set voltage (limit voltage) Rv that is a lower limit value of an allowable output voltage is set in advance. For example, when the water shortage state occurs, the output voltage of the polymer electrolyte fuel cell 3 greatly decreases, and when the first set voltage Rv is reached, the control unit 12 changes the output current of the polymer electrolyte fuel cell 3. Keep constant and wait for output voltage to rise. Eventually, when the output voltage of the polymer electrolyte fuel cell 3 rises to the second set voltage (permitted voltage) Pv set to a value larger than the first set voltage Rv, it is allowed to increase the output current. The controller 12 increases the output current of the polymer electrolyte fuel cell 3 again. As a result, the output voltage of the polymer electrolyte fuel cell 3 decreases again. The above operation is repeated sequentially. As a result, as shown in FIG. 5, in the water shortage state, the output current of the polymer electrolyte fuel cell 3 rises step by step when the system is started. On the other hand, for example, in an appropriate state, the output voltage of the polymer electrolyte fuel cell 3 does not drop greatly, so that the output current of the polymer electrolyte fuel cell 3 is linear (primary Rises functionally).

1-5. Humidification state adjustment process at startup The humidification state adjustment process A at startup is based on the verification result of the humidification state verification process V, and the humidification state of the polymer electrolyte fuel cell 3 at the time of system startup after the humidification state verification process V Is a step of adjusting In other words, the startup humidification state adjustment step A is based on the verification result of one or more humidification state verification steps V performed before that, and the humidification state of the polymer electrolyte fuel cell 3 at the time of system startup Is a step of adjusting In this example, in the starting humidification state adjustment step A, the humidification state of the polymer electrolyte fuel cell 3 is adjusted based on the verification result of the latest humidification state verification step V. For example, in FIG. 2, the startup humidification state adjustment step A2 is performed based on the verification result of the humidification state verification step V1, and the startup humidification state adjustment step A3 is performed based on the verification result of the humidification state verification step V2. Such start-up humidification state adjustment step A includes both adjusting the humidification state of the polymer electrolyte fuel cell 3 in the humidification increasing direction and adjusting the humidification decreasing direction.

  In the startup humidification state adjustment step A according to the present embodiment, based on the verification result obtained in the humidification state verification step V, the solid polymer fuel cell unit according to the humidification state of the polymer electrolyte fuel cell unit 3 The power generation start temperature set in order to define the conditions under which 3 starts power generation is adjusted.

When the verification result that the humidification state of the polymer electrolyte fuel cell 3 is a water shortage state is obtained in the humidification state verification step V, the humidification state of the polymer electrolyte fuel cell 3 is increased in the humidification direction (more wetted) Direction).
Therefore, when a verification result indicating a water shortage state is obtained, the startup humidification state adjustment step A in the present embodiment is set in order to define the conditions under which the polymer electrolyte fuel cell 3 starts power generation. The power generation start temperature is lowered below the standard power generation start temperature Ts, which is the power generation start temperature in the proper state. That is, as shown in FIG. 6, in the system start-up control at the time of system start-up, the power generation start temperature T1 (T1 <Ts) where the temperature of the polymer electrolyte fuel cell 3 is set to a value lower than the standard power generation start temperature Ts. ), The control unit 12 starts power generation and gradually increases the output current (power generation output) extracted from the polymer electrolyte fuel cell 3. Thus, by starting the power generation from a state where the temperature of the solid polymer fuel cell 3 is lower than the standard power generation start temperature Ts, the amount of generated water evaporated at the time of starting the system can be reduced, and the solid polymer The humidified state of the fuel cell 3 can be shifted in the direction of increasing humidification.

On the other hand, when the verification result that the humidification state of the polymer electrolyte fuel cell 3 is an excessive water state is obtained in the humidification state verification step V, the humidification state of the polymer electrolyte fuel cell 3 is reduced in the humidification direction ( What is necessary is just to make it transfer to the direction of drying more.
Therefore, when a verification result indicating that the water is excessive is obtained, the start-up humidification state adjustment step A in the present embodiment is set in order to define the conditions under which the polymer electrolyte fuel cell 3 starts power generation. The power generation start temperature is raised above the standard power generation start temperature Ts, which is the power generation start temperature in the proper state. That is, as shown in FIG. 6, in the system start-up control at the time of system start-up, the power generation start temperature T2 (T2> Ts) in which the temperature of the polymer electrolyte fuel cell 3 is set to a value higher than the standard power generation start temperature Ts. ), The controller 12 starts power generation and gradually increases the output current (power generation output) taken out from the polymer electrolyte fuel cell 3. In this way, by starting power generation from a state in which the temperature of the solid polymer fuel cell 3 is higher than the standard power generation start temperature Ts, the amount of evaporation of generated water at the time of starting the system is increased, and the solid polymer The humidified state of the fuel cell 3 can be shifted in the direction of decreasing humidification. In the time chart of FIG. 6, the time points at which power generation is started are also displayed in consideration of visibility.

More specifically, in order to shift the humidification state of the polymer electrolyte fuel cell 3 to the humidification increasing direction, the power generation start temperature is decreased by, for example, 5 to 10 ° C. with respect to the standard power generation start temperature Ts, and T1 To do. The decrease width in this case may be variable according to the degree of decrease in the output voltage of the polymer electrolyte fuel cell 3 recognized in the humidified state verification step V. That is, it is possible to adopt a configuration in which the lower power generation start temperature T1 is set as the degree of decrease in the output voltage in the humidified state verification step V is larger.
Alternatively, the power generation start temperature is increased by, for example, 5 to 10 ° C. with respect to the standard power generation start temperature Ts to T2 in order to shift the humidification state of the polymer electrolyte fuel cell 3 to the humidification decreasing direction. The range of increase in this case may be made variable according to the degree of instability of the output voltage of the polymer electrolyte fuel cell 3 recognized in the humidified state verification step V. That is, it is possible to employ a configuration in which a higher power generation start temperature T2 is set as the degree of instability of the output voltage in the humidified state verification process V is larger.
In addition, said setting reference | standard is an example to the last, A setting change is possible suitably according to the characteristic of the polymer electrolyte fuel cell 3. FIG.

1-6. Humidity state adjustment process at stop The humidification state adjustment process B at stop is based on the verification result of the humidification state verification process V, and the humidification state of the polymer electrolyte fuel cell 3 when the system is stopped after the humidification state verification process V Is a step of adjusting In other words, the humidification state adjustment process B at the time of stop is based on the verification result of one or more humidification state verification processes V performed before that, and the humidification state of the polymer electrolyte fuel cell 3 at the time of system stop Is a step of adjusting In this example, in the humidification state adjustment step B at the time of stop, the humidification state of the polymer electrolyte fuel cell 3 is adjusted based on the verification result of the latest humidification state verification step V. For example, in FIG. 2, the stop humidification state adjustment step B1 is performed based on the verification result of the humidification state verification step V1, and the stop humidification state adjustment step B2 is performed based on the verification result of the humidification state verification step V2. Based on the verification result of the state verification step V3, the stop humidification state adjustment step B3 is performed. Such a stop-time humidification state adjusting step B includes both adjusting the humidification state of the polymer electrolyte fuel cell 3 in the humidification increasing direction and adjusting the humidification decreasing direction.

  In the stop humidification state adjustment step B according to this embodiment, based on the verification result obtained in the humidification state verification step V, the power generation output is reduced when the system is stopped according to the humidification state of the polymer electrolyte fuel cell 3. The temperature of the polymer electrolyte fuel cell 3 at the start is adjusted.

When the verification result that the humidification state of the polymer electrolyte fuel cell 3 is a water shortage state is obtained in the humidification state verification step V, the humidification state of the polymer electrolyte fuel cell 3 is increased in the humidification direction (more wetted). Direction).
Therefore, when the verification result that the water is insufficient is obtained, in the stop humidification state adjustment step B in the present embodiment, the temperature of the polymer electrolyte fuel cell 3 is set to the temperature in the proper state (this example). Then, it is lower than the standard operating temperature Tr). That is, as shown in FIG. 7, in the system stop control at the time of system stop, after the temperature of the polymer electrolyte fuel cell 3 is set to T3 (T3 <Tr) lower than the standard operation temperature Tr, the control unit 12 is solid. The power generation is stopped by gradually decreasing the output current (power generation output) extracted from the polymer fuel cell 3. In this way, by reducing the power generation output from the state where the temperature of the polymer electrolyte fuel cell 3 is lower than the standard operating temperature Tr and stopping the power generation, the amount of evaporation of generated water when the system is stopped is reduced. Thus, the humidified state of the polymer electrolyte fuel cell 3 can be shifted in the direction of increasing humidification.

On the other hand, when the verification result that the humidification state of the polymer electrolyte fuel cell 3 is an excessive water state is obtained in the humidification state verification step V, the humidification state of the polymer electrolyte fuel cell 3 is reduced in the humidification direction ( What is necessary is just to make it transfer to the direction of drying more.
Therefore, when the verification result that the water is excessive is obtained, in the stop humidification state adjustment step B in the present embodiment, the temperature of the polymer electrolyte fuel cell 3 is set to the standard operation temperature in the proper state. Raise than Tr. That is, as shown in FIG. 7, in the system stop control at the time of system stop, after the temperature of the polymer electrolyte fuel cell 3 is set to T4 (T4> Tr) higher than the standard operation temperature Tr, the control unit 12 is solid. The power generation is stopped by gradually decreasing the output current (power generation output) extracted from the polymer fuel cell 3. In this way, by reducing the power generation output from the state where the temperature of the polymer electrolyte fuel cell 3 is higher than the standard operating temperature Tr and stopping the power generation, the amount of generated water evaporated when the system is stopped is increased. Thus, the humidified state of the polymer electrolyte fuel cell 3 can be shifted in the direction of decreasing humidification.

More specifically, the temperature at which the output current (power generation output) extracted from the polymer electrolyte fuel cell 3 starts to decrease is standardized in order to shift the humidification state of the polymer electrolyte fuel cell 3 toward the direction of increasing humidification. For example, the operating temperature Tr is lowered by 5 to 10 ° C. to obtain T3. The reduction width in this case may be variable depending on the degree of reduction in the output voltage of the polymer electrolyte fuel cell 3 recognized in the humidification state verification step V. That is, it is possible to employ a configuration in which the output current (power generation output) starts to decrease from a lower temperature T3 as the degree of decrease in the output voltage in the humidified state verification step V increases.
Alternatively, the temperature at which the output current (power generation output) taken out from the polymer electrolyte fuel cell 3 starts to decrease is set to the standard operating temperature Tr in order to shift the humidification state of the polymer electrolyte fuel cell 3 to the humidification decreasing direction. In contrast, for example, the temperature is increased by 5 to 10 ° C. to T4. The increase width in this case may be variable according to the degree of instability of the output voltage of the polymer electrolyte fuel cell 3 recognized in the humidified state verification step V. That is, it is possible to employ a configuration in which the output current (power generation output) starts to decrease from a higher temperature T4 as the degree of instability of the output voltage in the humidified state verification step V increases.
In addition, said setting reference | standard is an example to the last, A setting change is possible suitably according to the characteristic of the polymer electrolyte fuel cell 3. FIG.

  As described above, the control unit 12 adjusts the humidification state of the polymer electrolyte fuel cell 3 at the time of system start and system stop in the humidification increasing direction based on the verification result in the humidification state verification control, and Humidification state adjustment control including both adjustment in the direction of decreasing humidity is performed. Therefore, the humidification state verification control and the humidification state adjustment control appropriately adjust the humidification state of the polymer electrolyte fuel cell 3 when the system is started and when the system is stopped. Therefore, the performance of the polymer electrolyte fuel cell 3 is continued. Maintained well. In particular, a special humidification function for supplying moisture to the polymer electrolyte fuel cell 3 as in this embodiment (for example, a bubbler device that includes water vapor in the gas supplied to the anode 3a and the cathode 3b) ) And is operated under low humidification conditions such that the polymer electrolyte fuel cell 3 is humidified with water generated during power generation in the polymer electrolyte fuel cell 3 Even so, the humidification state of the polymer electrolyte fuel cell 3 can be appropriately adjusted by the humidification state verification control and the humidification state adjustment control.

2. Second Embodiment A second embodiment of the starting method and stopping method of the fuel cell system S according to the present invention will be described with reference to the drawings. In the fuel cell system S according to this embodiment, the method for adjusting the humidification state of the polymer electrolyte fuel cell 3 in the humidification state adjustment step A at startup and the humidification state adjustment step B at stop is the first implementation described above. It is different from the form. Below, the starting method and the stopping method of the fuel cell system S according to the present embodiment will be described in detail with a focus on differences from the first embodiment. Note that points not particularly specified are the same as those in the first embodiment.

2-1. In startup humidification state adjustment step A according to the present embodiment, based on the verification result obtained in the humidification state verification step V, the system is selected according to the humidification state of the polymer electrolyte fuel cell 3. The flow rate of at least one of the fuel gas and the oxygen-containing gas supplied to the polymer electrolyte fuel cell 3 at startup is adjusted.

  In the humidification state verification step V, when a verification result indicating that the water is insufficient is obtained, in the startup humidification state adjustment step A in this embodiment, the fuel gas and oxygen supplied to the polymer electrolyte fuel cell 3 at the time of system startup The flow rate of at least one of the contained gases is decreased from the flow rate in the proper state (in this example, the standard flow rate Fs is set). That is, as shown in FIG. 8, in the system start-up control at the time of system start-up, at least one of fuel gas and oxygen-containing gas is supplied to the polymer electrolyte fuel cell 3 from a preset standard flow rate Fs. The control unit 12 starts power generation while supplying at a lower flow rate F1 (F1 <Fs) and gradually increases the output current (power generation output) extracted from the polymer electrolyte fuel cell 3. Thus, by starting the power generation in a state where the supply flow rate of at least one of the fuel gas and the oxygen-containing gas is lower than the standard flow rate Fs, the solid polymer fuel cell 3 of the polymer polymer fuel cell 3 is activated by these gases when the system is started. The amount of generated water taken out to the outside can be reduced, and the humidified state of the polymer electrolyte fuel cell 3 can be shifted in the direction of increasing humidification.

  On the other hand, in the humidified state verification step V, when a verification result indicating that there is an excessive water state is obtained, in the startup humidified state adjustment step A in this embodiment, the fuel supplied to the polymer electrolyte fuel cell 3 at the time of system startup The flow rate of at least one of the gas and the oxygen-containing gas is increased from the standard flow rate Fs in the proper state. That is, as shown in FIG. 8, in the system start-up control at the time of system start-up, at least one of fuel gas and oxygen-containing gas is supplied to the polymer electrolyte fuel cell 3 from a preset standard flow rate Fs. The control unit 12 starts power generation while supplying at a higher flow rate F2 (F2> Fs) and gradually increases the output current (power generation output) extracted from the polymer electrolyte fuel cell 3. As described above, by starting power generation in a state where the supply flow rate of at least one of the fuel gas and the oxygen-containing gas is higher than the standard flow rate Fs, the solid polymer fuel cell 3 is activated by these gases when the system is started. It is possible to increase the amount of generated water to be taken to the outside and shift the humidified state of the polymer electrolyte fuel cell 3 in the direction of decreasing humidification.

  More specifically, at least one of a fuel gas and an oxygen-containing gas supplied to the polymer electrolyte fuel cell 3 in order to shift the humidification state of the polymer electrolyte fuel cell 3 toward the humidification increasing direction. The flow rate is reduced by, for example, 5 to 15% with respect to the standard flow rate Fs to be F1. Alternatively, the flow rate of at least one of the fuel gas and the oxygen-containing gas supplied to the solid polymer fuel cell 3 is changed to the standard flow rate in order to shift the humidification state of the solid polymer fuel cell 3 to the humidification decreasing direction. For example, F2 is raised by 5 to 20% with respect to Fs. The change width in these cases may be made variable according to the degree of decrease or instability of the output voltage of the polymer electrolyte fuel cell 3 recognized in the humidified state verification step V. In addition, said setting reference | standard is an example to the last, A setting change is possible suitably according to the characteristic of the polymer electrolyte fuel cell 3. FIG.

2-2. Stop humidification state adjustment process In the stop humidification state adjustment process B according to the present embodiment, based on the verification result obtained in the humidification state verification process V, the system is selected according to the humidification state of the polymer electrolyte fuel cell 3. The flow rate of at least one of the fuel gas and the oxygen-containing gas at the time of starting to decrease the power generation output at the time of stopping is adjusted.

  In the humidification state verification step V, when a verification result indicating that the water is insufficient is obtained, in the stop humidification state adjustment step B in the present embodiment, the fuel gas supplied to the polymer electrolyte fuel cell 3 before the system is stopped and The flow rate of at least one of the oxygen-containing gas is reduced from the flow rate in the proper state (in this example, the operation standard flow rate Fr). That is, as shown in FIG. 9, in the system stop control at the time of system stop, the supply flow rate of at least one of the fuel gas and the oxygen-containing gas supplied to the polymer electrolyte fuel cell 3 is set at the time of operation. After setting F3 (F3 <Fr) lower than the standard flow rate Fr, the control unit 12 gradually reduces the output current (power generation output) extracted from the polymer electrolyte fuel cell 3 and stops power generation. In this way, power generation is performed by reducing the power generation output from a state where the supply flow rate of at least one of the fuel gas and the oxygen-containing gas supplied to the polymer electrolyte fuel cell 3 is lower than the standard flow rate Fr during operation. Is stopped, the amount of generated water brought out of the polymer electrolyte fuel cell 3 by these gases when the system is stopped is reduced, and the humidification state of the polymer electrolyte fuel cell 3 is increased. Can be moved in the direction.

  On the other hand, when a verification result indicating that there is an excessive water state is obtained in the humidification state verification step V, in the stop humidification state adjustment step B in the present embodiment, it is supplied to the polymer electrolyte fuel cell 3 before the system is stopped. The flow rate of at least one of the fuel gas and the oxygen-containing gas is increased from the operating standard flow rate Fr in an appropriate state. That is, as shown in FIG. 9, in the system stop control at the time of system stop, the supply flow rate of at least one of the fuel gas and the oxygen-containing gas supplied to the polymer electrolyte fuel cell 3 is set at the time of operation. After setting F4 (F4> Fr) higher than the standard flow rate Fr, the control unit 12 gradually reduces the output current (power generation output) extracted from the polymer electrolyte fuel cell 3 and stops power generation. As described above, the power generation output is reduced from the state in which the supply flow rate of at least one of the fuel gas and the oxygen-containing gas supplied to the polymer electrolyte fuel cell 3 is higher than the standard flow rate Fr during operation. Is stopped, the amount of generated water brought out of the polymer electrolyte fuel cell 3 by these gases when the system is stopped is increased, and the humidification state of the polymer electrolyte fuel cell 3 is reduced by humidification. Can be moved in the direction.

  More specifically, at least one of a fuel gas and an oxygen-containing gas supplied to the polymer electrolyte fuel cell 3 in order to shift the humidification state of the polymer electrolyte fuel cell 3 toward the humidification increasing direction. The flow rate is decreased by, for example, 5 to 15% with respect to the standard flow rate Fr to be F3. Alternatively, the flow rate of at least one of the fuel gas and the oxygen-containing gas supplied to the solid polymer fuel cell 3 is changed to the standard flow rate in order to shift the humidification state of the solid polymer fuel cell 3 to the humidification decreasing direction. For example, F4 is raised by 5 to 20% with respect to Fr. The change width in these cases may be made variable according to the degree of decrease or instability of the output voltage of the polymer electrolyte fuel cell 3 recognized in the humidified state verification step V. In addition, said setting reference | standard is an example to the last, A setting change is possible suitably according to the characteristic of the polymer electrolyte fuel cell 3. FIG.

  As described above, also in the present embodiment, the humidified state of the polymer electrolyte fuel cell 3 is appropriately adjusted by the humidified state verification control and the humidified state adjustment control when the system is started and when the system is stopped. By appropriately adjusting the humidified state of the fuel cell 3, the performance of the polymer electrolyte fuel cell 3 can be maintained continuously and satisfactorily.

[Other Embodiments]
(1) In each of the above embodiments, in the fuel cell system S, both the startup humidification state adjustment step A and the stop humidification state adjustment step B are executed based on the verification result of the humidification state verification step V. Was described as an example. However, the embodiment of the present invention is not limited to this. That is, it is sufficient that at least the startup humidification state adjustment step A is executed based on the verification result of the humidification state verification step V, and it is not essential that the stop time humidification state adjustment step B is executed.

(2) In each of the above embodiments, in the humidification state adjustment step A during start-up and the humidification state adjustment step B during stoppage, the polymer electrolyte fuel cell 3 The case where the humidified state is adjusted has been described as an example. However, the embodiment of the present invention is not limited to this. That is, it is good also as a structure by which the humidification state of the polymer electrolyte fuel cell 3 is adjusted based on the total of the verification result of the several humidification state verification process V performed before that. For example, in the example shown in FIG. 2, the configuration in which the startup humidification state adjustment step A3 is performed based on the overall verification results of the humidification state verification steps V1 and V2, and the verification results of the humidification state verification steps V1 to V3 Based on this, it is possible to employ a configuration in which the stop-time humidification state adjustment step B3 is performed.

(3) In the first embodiment, the polymer electrolyte fuel cell is based on the verification results obtained in the humidification state verification step V in the startup humidification state adjustment step A and the stop humidification state adjustment step B. The operation parameter related to the temperature of the cell 3 is adjusted. In the second embodiment, the operation parameter related to the flow rate of the fuel gas and the oxygen-containing gas supplied to the polymer electrolyte fuel cell 3 is adjusted as an example. explained. However, the embodiment of the present invention is not limited to this. That is, based on the verification result obtained in the humidified state verification step V, for example, the operation parameter relating to the flow rate of hot water (cooling water) circulating in the cooling water circulation path 13 provided in the cooling means C may be adjusted. good.

  For example, at the time of starting the system, the temperature of the polymer electrolyte fuel cell 3 increases more slowly by increasing the flow rate of the cooling water. Therefore, by starting the power generation after increasing the flow rate of the cooling water in the startup humidification state adjustment step A, the amount of generated water evaporated at the time of system startup is further reduced, and the solid polymer fuel cell 3 The humidified state can be shifted in the direction of increasing humidification. On the other hand, the temperature of the polymer electrolyte fuel cell 3 increases more rapidly by decreasing the flow rate of the cooling water. Therefore, by starting the power generation after reducing the flow rate of the cooling water, the amount of generated water evaporated at the time of starting the system is increased, and the humidification state of the polymer electrolyte fuel cell 3 is reduced in the humidification direction. Can be migrated.

  For example, when the system is stopped, the temperature of the polymer electrolyte fuel cell 3 is more rapidly decreased by increasing the flow rate of the cooling water. Therefore, by increasing the flow rate of the cooling water in the stop humidified state adjusting step B and starting to decrease the power generation output and stopping the power generation, the evaporation amount of the generated water at the time of the system stop is reduced, so that the solid polymer The humidified state of the fuel cell 3 can be shifted in the direction of increasing humidification. On the other hand, by decreasing the flow rate of the cooling water, the temperature drop of the polymer electrolyte fuel cell 3 becomes slower. Therefore, by reducing the flow rate of the cooling water and then starting to reduce the power generation output and stopping the power generation, the amount of generated water evaporated when the system is stopped is increased, and the polymer electrolyte fuel cell 3 is in a humidified state. Can be shifted in the direction of decreasing humidification.

(4) In each of the above embodiments, the humidification state of the polymer electrolyte fuel cell 3 is adjusted in the humidification increasing direction and the humidification decreasing direction based on the verification result of the humidification state verification step V. The case where the startup humidification state adjustment step A including both of the above is executed has been described as an example. However, the embodiment of the present invention is not limited to this. That is, without performing such a humidification state verification step V, or regardless of the verification result of the humidification state verification step V, the humidification state of the polymer electrolyte fuel cell 3 is increased in the humidification increasing direction. It is good also as a structure which performs the "humidification state increase process at the time of starting" to transfer. In such a startup humidified state increasing step, the standard power generation start described in the first embodiment is set to the power generation start temperature set to define the conditions under which the polymer electrolyte fuel cell 3 starts power generation. Decreasing the temperature Ts or reducing the flow rate of at least one of the fuel gas and the oxygen-containing gas supplied to the polymer electrolyte fuel cell 3 from the standard flow rate Fs described in the second embodiment. Starting power generation in a state in which the cooling water is supplied, or starting power generation in a state where the flow rate of the cooling water circulating in the cooling water circulation path 13 provided in the cooling means C is increased from the flow rate in the proper state. ,I do.

(5) Or based on the verification result of the humidification state verification process V, it is good also as a structure which performs said humidification state increase process at the time of starting. That is, in the humidification state verification step V, it is configured to verify whether at least the humidification state of the polymer electrolyte fuel cell 3 is in a water shortage state, and the startup humidification state increase step is performed only when it is determined as a water shortage state. It is also suitable as a configuration for execution. In this case, in the humidification state verification step V, the humidification state of the polymer electrolyte fuel cell 3 is determined based on the output voltage of the polymer electrolyte fuel cell 3 at the time of starting the system, as in the above embodiments. It can be set as the structure to verify. Alternatively, the humidified state verification step V may be configured to verify the humidified state of the polymer electrolyte fuel cell 3 based on the output current of the polymer electrolyte fuel cell 3 at the time of system startup. . That is, with respect to the output voltage of the polymer electrolyte fuel cell 3, in the configuration in which the first set voltage (limit voltage) Rv and the second set voltage (allowable voltage) Pv are set as described in the above embodiments. When the system is in a water-deficient state, the output current of the polymer electrolyte fuel cell 3 increases in a stepwise manner when the system is started. Therefore, it is also suitable as a configuration in which it is determined that the water shortage state occurs when it is recognized that the output current of the polymer electrolyte fuel cell 3 increases stepwise in the humidified state verification step V.

  The present invention can be suitably used for a fuel cell system that is operated under low humidification conditions.

S Fuel cell system 3 Polymer electrolyte fuel cell 3a Anode 3b Cathode 3c Electrolyte V Humidity state verification process A Humidity state adjustment process at startup (humidification state increase process at startup)
B. Humidity adjustment process during stop

Claims (7)

A starting method of a fuel cell system comprising a polymer electrolyte fuel cell having an anode to which a fuel gas is supplied, a cathode to which an oxygen-containing gas is supplied, and an electrolyte provided between the anode and the cathode,
A humidification state verification step of verifying a humidification state of the polymer electrolyte fuel cell at the time of system startup;
Based on the verification result of the humidification state verification step, adjusting the humidification state of the polymer electrolyte fuel cell at the time of system startup after the humidification state verification step and adjusting the humidification decrease direction. A start-up humidification state adjusting step including both of the steps.   The humidification state verification step monitors the output voltage of the polymer electrolyte fuel cell, and based on the output voltage, the polymer electrolyte fuel cell is out of a water shortage state, an excessive water state, and an appropriate state. The method of starting a fuel cell system according to claim 1, which is a step of verifying which state of the fuel cell system is present. In the humidified state verification step,
When the output voltage value of the polymer electrolyte fuel cell is lower than the normal output voltage value range expected in the appropriate state, it is determined as the water shortage state,
When the stability of the output voltage of the polymer electrolyte fuel cell exceeds the degree of stability of the output voltage expected in the appropriate state, it is determined as the excessive water state,
The method for starting the fuel cell system according to claim 2, wherein the appropriate state is determined when neither the water-deficient state nor the excessive water state is present. The startup humidification state adjustment step includes:
If the verification result that the humidification state of the polymer electrolyte fuel cell in the humidification state verification step is the water shortage state is obtained,
Lowering the power generation start temperature set to define the conditions under which the polymer electrolyte fuel cell starts power generation, lower than the power generation start temperature in the proper state, or the solid polymer fuel The power generation is started in a state where the flow rate of at least one of the fuel gas and the oxygen-containing gas supplied to the battery cell is reduced from the flow rate in the proper state. Or a starting method of the fuel cell system according to 3; The startup humidification state adjustment step includes:
If the verification result that the humidification state of the polymer electrolyte fuel cell is the excessive water state in the humidification state verification step is obtained,
Increasing the power generation start temperature set for defining the conditions under which the polymer electrolyte fuel cell starts power generation, higher than the power generation start temperature in the proper state, or the polymer electrolyte fuel The power generation is started in a state where the flow rate of at least one of the fuel gas and the oxygen-containing gas supplied to the battery cell is increased from the flow rate in the proper state. To 4. The method for starting the fuel cell system according to any one of claims 1 to 4. A starting method of a fuel cell system comprising a polymer electrolyte fuel cell having an anode to which a fuel gas is supplied, a cathode to which an oxygen-containing gas is supplied, and an electrolyte provided between the anode and the cathode,
In the case where the solid polymer fuel cell is in an appropriate state in which the solid polymer fuel cell is maintained in an appropriate humidified state, the power generation start temperature set to define the conditions under which the polymer electrolyte fuel cell starts power generation The flow rate is lower than the power generation start temperature, or the flow rate of at least one of the fuel gas and the oxygen-containing gas supplied to the polymer electrolyte fuel cell is reduced from the flow rate in the proper state. A start-up method of a fuel cell system including a start-up humidified state increasing step of starting power generation in a state. The polymer electrolyte fuel cell having an anode to which a fuel gas is supplied, a cathode to which an oxygen-containing gas is supplied, an electrolyte provided between the anode and the cathode, and the cooling water circulating through the cooling water circuit A cooling means for cooling the polymer electrolyte fuel cell, and a starting method of the fuel cell system comprising:
At the time of starting to generate power in a state where the flow rate of the cooling water circulating through the cooling water circulation path is increased from the flow rate when the polymer electrolyte fuel cell is in an appropriate state maintained in an appropriate humidified state A starting method of a fuel cell system having a humidified state increasing step.

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