JP2016018650A - Fuel cell system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To stabilize output by enhancing the effectiveness of suppression of over-drying and over-wetting of an electrolyte membrane during load variation transition period.SOLUTION: When performing increase and decrease control of gas flow rate and gas pressure under transient situation of load variation, depending on the load variation, a fuel cell stack shifts the change timing of gas pressure rate increase and decrease change to the delay side, for the change timing of gas flow rate increase and decrease change beneficial for shifting over-wetting or over-drying to the proper wetting side. If the gas pressure increase and decrease is beneficial for shifting the over-wetting or over-drying to the proper wetting side, the change timing of gas flow rate increase and decrease is shifted to the delay side, for the change timing of the gas pressure increase and decrease change.SELECTED DRAWING: Figure 5

Description

  The present invention relates to a fuel cell system.

  The fuel cell stack constituting the fuel cell system receives the supply of the fuel gas and the oxygen-containing oxidant gas, generates power, and outputs the generated power to an external load. In such a fuel cell system, the above-described fuel gas and oxidant gas, for example, hydrogen gas and air, are usually supplied in a gas amount corresponding to the required power required by an external load. Fuel cell power generation is based on an electrochemical reaction between hydrogen in hydrogen gas and oxygen in the air through an electrolyte membrane having proton conductivity, and the electrolyte membrane exhibits proton conductivity in an appropriate wet state. The output is stable. For this reason, since the output is not stable if the electrolyte membrane is overdried or overwet, it is desirable to suppress overdrying or overwetting of the electrolyte membrane. By the way, the required load is not always uniform. For example, in a vehicle equipped with a fuel cell system, a sudden increase in load caused by a sudden depression of the accelerator and a reduction in load caused by the return of the accelerator are often repeated. If the electrolyte membrane is overdried or wetted during such load fluctuation transients, the stability of the output will be impaired. Therefore, a method to suppress overdrying and overwetting of the electrolyte membrane even during the above-mentioned load reduction transient period. Has been proposed (for example, Patent Document 1).

JP 2012-109182 A

  In the above-mentioned patent document, in order to suppress overdrying and overwetting of the electrolyte membrane in the transition period of load reduction, the gas flow rate of the cathode gas itself is controlled along with detection of overdrying and overwetting of the electrolyte membrane, The control of the gas passage time through the control of the gas pressure of the cathode gas is executed in accordance with the detection of overdrying or overwetting of the electrolyte membrane. Gas flow control and gas pressure control are useful for suppressing electrolyte membrane overdrying and overwetting, but either of these controls limits the suppression of electrolyte membrane overdrying or overwetting, so load fluctuation transients It has been requested to stabilize the output by improving the effectiveness of suppressing excessive drying and overwetting of the electrolyte membrane in the period.

  In view of the above-described problems, an object of the present invention is to provide a new technique that can improve the stabilization of the output of a fuel cell in a load fluctuation transition period.

  In order to achieve at least a part of the problems described above, the present invention can be implemented as the following forms.

  (1) According to one aspect of the present invention, a fuel cell system is provided. The fuel cell system includes a fuel cell stack that generates power upon receiving supply of a reaction gas, and a control parameter based on a load requirement required for the fuel cell stack, and a gas flow rate and a gas pressure. A gas supply control unit that controls gas supply of the reaction gas to the fuel cell stack with control parameters; a load variation determination unit that determines whether or not a load variation is in a transient state based on the load request; A wetness determination unit that determines a wet state of the fuel cell stack. When the gas supply control unit determines that the load variation determination unit is in a state of transient load variation, the gas supply control unit shifts the wet state determined by the wet determination unit out of the control parameters to a proper moisture level. The change timing of the other control parameter is shifted to the delay side with respect to the change timing of one control parameter of the gas flow rate or gas pressure that contributes to this.

  In this type of fuel cell system, when the wet state of the fuel cell stack deviates from the proper wet state in a transient state of load fluctuation that has caused an increase or decrease in the required load, the wet state shifts to the proper wet state. One control parameter of the gas flow rate or gas pressure contributing to the change is changed, and the other control parameter is changed after being delayed. Due to such a change in the change timing, during the change delay, the other control parameter is maintained in the state before the load change. The state of the gas flow rate or gas pressure before the load change maintained in this way becomes a state of reduction or increase of the gas flow rate or reduction or increase of the gas pressure with respect to the gas flow rate or gas pressure corresponding to the change of the load request. . Therefore, one control parameter that is a gas flow rate or gas pressure that is useful for shifting the wet state to a proper wetness state, and the other control parameter that is the gas flow rate or gas pressure that maintains the state before the load change. For example, the gas supply situation brought about by the reduction of moisture removal, which is useful for shifting the wet state to an appropriate side because the wet state is excessively dry, the reduction of gas flow rate and the increase of gas pressure, which lead to moisture retention Various gas flow rate / pressure situations such as a situation, or a gas flow rate increase or gas pressure reduction situation that is beneficial for proper transition, and such a gas supply situation is realized in a load fluctuation transient. If the wet state is excessively wet, the situation of gas flow rate increase and gas pressure reduction leading to an increase in moisture removal that is beneficial for shifting this to the proper side, or gas flow rate reduction beneficial for proper transition Various gas flow rate / pressure situations, such as the situation of an increase in gas pressure, are realized in a load fluctuation transient. As a result, according to the fuel cell system of this embodiment, it is possible to improve the effectiveness of suppressing the overdrying and overwetting of the fuel cell stack, specifically, the electrolyte membrane in the load fluctuation transition period, and to stabilize the output. .

  (2) In the fuel cell system according to the above aspect, the gas supply control unit performs an adjustment adjustment that can shift the wet state determined by the wetness determination unit to a proper wetness side when changing the one control parameter. The one control parameter is changed to the gas flow rate or gas pressure that has passed, and the change timing of the other control parameter that is the gas flow rate or gas pressure that has not passed the optimization adjustment is changed with respect to the change timing that has passed the optimization adjustment You may make it shift to the delay side. In this way, the gas supply status to the fuel cell stack will be various situations of increasing or decreasing the gas flow rate and pressure that will bring about a decrease in moisture removal, moisture retention, or an increase in moisture removal that is beneficial in a wet state. This situation can be realized. As a result, according to the fuel cell system of this embodiment, the fuel cell stack in the transition period of the load fluctuation, more specifically, the effectiveness of suppressing the excessive drying and overwetting of the electrolyte membrane is further improved, and the output corresponding to the load is stabilized. Can be obtained.

  (3) In the fuel cell system according to the above aspect, when the gas supply control unit determines that the load variation determination unit is in a load increase transition, the optimization adjustment is performed as an increase optimization adjustment of a gas flow rate or a gas pressure. The one control parameter may be changed to the gas flow rate or gas pressure that has undergone the increase optimization adjustment. In this way, the state of gas supply to the fuel cell stack will increase the gas flow rate or the gas pressure more effectively resulting in reduced moisture removal, moisture retention, or increased moisture removal that is beneficial in a wet state. This situation can be realized. As a result, according to the fuel cell system of this embodiment, the fuel cell stack in the transition period of the increase fluctuation of the load, more specifically, the effectiveness of suppressing the overdrying and overwetting of the electrolyte membrane is further improved to cope with the increased load. Output can be obtained stably.

  (4) In the fuel cell system according to the above aspect, the gas supply control unit determines that the change of the one control parameter to the gas flow rate or the gas pressure after the increase optimization adjustment is determined to be wet proper by the wetness determination unit. The increase adjustment target value may be temporarily larger than the increase adjustment target value based on the load request in the wet state. In this way, the gas supply to the fuel cell stack is such that the gas flow rate or gas pressure temporarily increases to an increase adjustment target value that is larger than the increase adjustment target value when increasing the gas flow rate or gas pressure in response to an increasing load. Made at gas pressure. Such an increase in gas flow rate or gas pressure is a gas supply situation in which a decrease in moisture removal, moisture retention, or an increase in moisture removal is more prominent in the transient state of fluctuations in load increase. Become. As a result, according to the fuel cell system of this embodiment, the fuel cell stack in the transition period of the load increase, more specifically, the effectiveness of suppressing the excessive drying and overwetting of the electrolyte membrane is further improved, and the output corresponding to the increased load is increased. Can be stabilized.

  (5) In the fuel cell system according to the above aspect, when the gas supply control unit determines that the load fluctuation determination unit is in a load reduction transition, the optimization adjustment is performed by reducing the gas flow rate or the gas pressure. The one control parameter may be changed to the gas flow rate or gas pressure that has undergone the reduction optimization. In this way, the gas supply status to the fuel cell stack can be reduced by reducing the gas flow rate or increasing the gas pressure, which effectively reduces the moisture removal and moisture retention, or increases the moisture removal, which is beneficial in a wet state. This situation can be realized. As a result, according to this form of the fuel cell system, the fuel cell stack in the transition period of the load reduction fluctuation, more specifically, the effectiveness of suppressing excessive drying and overwetting of the electrolyte membrane is further improved to cope with the reduced load. Output can be obtained stably.

  (6) In the fuel cell system according to the above aspect, the gas supply control unit determines that the change of the one control parameter to the gas flow rate or the gas pressure after the reduction optimization adjustment is determined as appropriate by the wetness determination unit. The reduction adjustment target value may be temporarily smaller than the reduction adjustment target value based on the load request in the wet state. In this way, the gas supply to the fuel cell stack is such that the gas flow rate or the gas flow rate temporarily corresponding to a reduction adjustment target value smaller than the reduction adjustment target value when the gas flow rate or the gas pressure is reduced corresponding to the load to be reduced. Made at gas pressure. This reduction in gas flow rate or gas pressure is a gas supply situation in which a decrease in moisture removal, moisture retention, or an increase in moisture removal is more prominent in a transitional period of load reduction fluctuation. Become. As a result, according to the fuel cell system of this embodiment, the fuel cell stack in the transition period of load reduction, more specifically, the effectiveness of suppressing overdrying and overwetting of the electrolyte membrane is further improved, and the output corresponding to the reduced load is further increased. Can be stabilized.

  The present invention relates to a fuel cell stack operation method, a vehicle equipped with a fuel cell system and using the generated power as a driving force, and a stationary power generation system using the fuel cell stack as a power source. Is also applicable.

It is explanatory drawing which shows the fuel cell mounting vehicle 20 as embodiment of this invention in planar view roughly. It is a flowchart which shows the control procedure in the condition of the increase transient of a demand load among the electric power generation control of the fuel cell stack 100 in the condition of the fluctuation of a demand load. It is a flowchart which shows the detail of the excessive wet recovery 1st process in the condition of the increase transient of a request | requirement load. It is explanatory drawing explaining the content of the determination process in an overhumidity recovery 1st process. It is explanatory drawing which illustrates schematically the condition of the gas supply brought about by the overhumidity recovery 1st process in the condition of the increase transient of a request | requirement load. It is explanatory drawing which shows roughly the mode of the overwetting optimization obtained by the overwetting recovery 1st process in the condition of the increase transient of a request | requirement load. It is a flowchart which shows the detail of the overdrying recovery 1st process in the condition of the increase transient of a request | requirement load. It is explanatory drawing explaining the content of the determination process in an overdrying recovery 1st process. It is explanatory drawing which illustrates roughly the condition of the gas supply brought about by the overdrying recovery 1st process in the condition of the increase transient of a required load. It is explanatory drawing which shows roughly the mode of the overdrying optimization obtained by the overdrying recovery 1st process in the condition of the increase transient of a required load. 4 is a flowchart showing a control procedure of power generation control of the fuel cell stack 100 under a situation where the required load is reduced. It is a flowchart which shows the detail of the excessive wet recovery 2nd process in the condition of the reduction | decrease transient of a demand load. It is explanatory drawing which illustrates roughly the condition of the gas supply brought about by the overhumidity recovery 2nd process in the condition of the reduction | decrease transient of a demand load. It is explanatory drawing which shows schematically the mode of the overwetting optimization obtained by the overwetting recovery 2nd process in the condition of the reduction | decrease transient of a demand load. It is a flowchart which shows the detail of the overdrying recovery 2nd process in the condition of the reduction | decrease transient of a required load. It is explanatory drawing which illustrates schematically the condition of the gas supply brought about by the overdrying recovery 2nd process in the condition of the reduction | decrease transient of a demand load. It is explanatory drawing which shows roughly the mode of the overdrying optimization obtained by the overdrying recovery 2nd process in the condition of the increase transient of a request | requirement load. It is explanatory drawing which illustrates schematically the gas supply condition in the overhumidity recovery 1st process made in the condition of the increase transient of a required load in the fuel cell stack 100 of 2nd Example. It is explanatory drawing which illustrates roughly the gas supply condition in the overdrying recovery 1st process made in the condition of the increase transient of a required load in the fuel cell stack 100 of 2nd Example. It is explanatory drawing which shows the change of the processing content of the overdrying recovery 1st process in the condition of the increase transient of the request | requirement load in previous embodiment, and transition of the gas supply condition accompanying this. It is explanatory drawing which shows the advantage at the time of making the gas flow rate increase control for wet optimization become a large increase adjustment target value temporarily. It is explanatory drawing which shows other embodiment which makes the gas flow rate increase control for wet optimization become a big increase adjustment target value temporarily. It is explanatory drawing which shows the change of the processing content of the excessive drying recovery 2nd process in the condition of reduction reduction of the required load in previous embodiment, and transition of the gas supply condition accompanying this.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is an explanatory view schematically showing a fuel cell vehicle 20 as an embodiment of the present invention in plan view.

  As shown in the figure, this fuel cell vehicle 20 has a fuel cell system 30 mounted on a vehicle body 22. The fuel cell system 30 includes a fuel cell stack 100, a hydrogen gas supply system 120 including a hydrogen gas tank 110, an air supply system 140 including a motor-driven compressor 130, a cooling system 160 including a radiator 150 and a fan 152, A secondary battery 172 and a DC / DC converter 174 are provided. The fuel cell system 30 supplies the power generated by the fuel cell stack 100 or the charging power of the secondary battery 172 to a load including the front-wheel drive motor 170.

  The fuel cell stack 100 includes battery cells, and the battery cells include both anode 102 and cathode 103 electrodes on both sides of the electrolyte membrane 101 as shown in the enlarged schematic view of FIG. The anode 102 and the cathode 103 are joined to both membrane surfaces of the electrolyte membrane 101 to form a membrane electrode assembly (MEA) together with the electrolyte membrane 101. In addition, the battery cell includes an anode-side gas diffusion layer 104 and a cathode-side gas diffusion layer 105 that sandwich the MEA from both sides (see FIG. 1), and both the gas diffusion layers are joined to corresponding electrodes. Yes.

  The electrolyte membrane 101 is a proton conductive ion exchange membrane formed of a solid polymer material, for example, a fluorine-based resin, and exhibits good electrical conductivity in a wet state. The anode 102 and the cathode 103 include a catalyst (for example, platinum or a platinum alloy), and are formed by supporting these catalysts on a conductive carrier (for example, carbon particles). The anode-side gas diffusion layer 104 and the cathode-side gas diffusion layer 105 are formed using a conductive porous member having gas permeability, for example, carbon paper or carbon cloth as a porous substrate.

  The fuel cell stack 100 has a stack structure configured by stacking the battery cells described above, and is located below the vehicle floor between the front wheel FW and the rear wheel RW. The fuel cell stack 100 generates electricity by causing an electrochemical reaction between hydrogen in hydrogen gas supplied from a hydrogen gas supply system 120 and an air supply system 140 described later and oxygen in the air in each battery cell unit. The load such as the motor 170 is driven by the generated power. The power generation state of the fuel cell stack 100 is measured by the current sensor 106, and the measurement result is output from the current sensor 106 to the control device 200 described later. In this case, the number of stacked battery cell units can be arbitrarily set according to the output required for the fuel cell stack 100.

  The hydrogen gas supply system 120 includes a hydrogen supply path 121 extending from the hydrogen gas tank 110 to the fuel cell stack 100, a circulation path 122 for circulating unconsumed hydrogen gas (anode offgas) to the hydrogen supply path 121, and the anode offgas to the atmosphere. A discharge path 123 for discharging is provided. The hydrogen gas supply system 120 passes through the opening / closing of the opening / closing valve 124 of the hydrogen supply path 121 and the pressure reduction by the pressure reducing valve 125, and supplies the hydrogen gas in the hydrogen gas tank 110 to the fuel cell stack 100 (specifically, each battery cell). To the anode 102). At this time, the hydrogen gas supply system 120 supplies a hydrogen gas having a flow rate that is the sum of the flow rate adjusted by the hydrogen supply device 126 downstream of the pressure reducing valve 125 and the circulation flow rate adjusted by the circulation pump 127 of the circulation path 122. This is supplied to the anode of the fuel cell stack 100. Further, the hydrogen gas supply system 120 supplies hydrogen gas to the anode of the fuel cell stack 100 at various gas pressures by changing the degree of pressure reduction by the pressure reducing valve 125. The hydrogen gas flow rate and gas pressure when supplying hydrogen gas to the fuel cell stack 100 are determined by the control device 200 described later based on the operation of the accelerator 180, and correspond to the load required for the fuel cell stack 100. It becomes. In the fuel cell stack 100 of the present embodiment, the gas flow rate and gas pressure of the hydrogen gas at the time of hydrogen gas supply are adjusted by the pressure reduction valve 125 by the control device 200 and the flow rate adjustment by the hydrogen supply device 126. Can be adjusted individually. The hydrogen gas supply system 120 appropriately releases the anode off-gas to the atmosphere via the discharge path 142 through the opening / closing adjustment of the opening / closing valve 129 of the discharge path 123 branched from the circulation path 122.

  The air supply system 140 includes an oxygen supply path 141 that reaches the fuel cell stack 100 via the compressor 130 and a discharge path 142 that discharges unconsumed air (cathode offgas) to the atmosphere. The air supply system 140 adjusts the flow of the air taken in from the open end of the oxygen supply path 141 in the compressor 130 and the pressure in the pressure adjustment valve 145 downstream thereof, and then the fuel cell stack 100 ( Specifically, the cathode off-gas is released to the atmosphere via the discharge path 142 at a flow rate adjusted by the discharge flow rate adjustment valve 143 of the discharge path 142 while being supplied to the cathode 103) of each battery cell normally via the oxygen supply path 141. . When air supply and cathode off-gas discharge are performed by the air supply system 140 in this way, the air supply system 140 sets the discharge flow rate adjustment valve 143 of the oxygen supply path 141 to a predetermined opening, and then the air by the compressor 130. Supply. Even in the air supply amount at this time, similarly to the hydrogen gas, the supply amount is determined by the control device 200 based on the operation of the accelerator 180 and corresponds to the load required for the fuel cell stack 100. In the fuel cell stack 100 of the present embodiment, the gas flow rate and the gas pressure of the air at the time of air supply are individually adjusted by the flow rate adjustment at the compressor 130 and the pressure adjustment at the pressure adjustment valve 145 by the control device 200. Adjustable. The discharge flow rate adjusting valve 143 adjusts the back pressure on the cathode side through the flow rate adjustment by the control device 200.

  The cooling system 160 includes a circulation path 161 that circulates the cooling medium from the radiator 150 to the fuel cell stack 100, a bypass path 162, a three-way flow rate adjustment valve 163 at the path junction, a circulation pump 164, and a temperature sensor 166. Prepare. The cooling system 160 guides the cooling medium heat-exchanged by the radiator 150 to the in-cell circulation path (not shown) of the fuel cell stack 100 through the circulation path 161, and cools the fuel cell stack 100 to a predetermined temperature. In this case, the driving amount of the circulation pump 164, that is, the circulation supply amount of the cooling medium and the adjustment flow rate by the three-way flow rate adjustment valve 163 are detected by the fuel cell temperature (cell temperature) as the detection temperature of the temperature sensor 166 and the current sensor 106. It is determined by the control device 200 based on the power generation state.

  The secondary battery 172 is connected to the fuel cell stack 100 via a DC / DC converter 174, functions as a power source different from the fuel cell stack 100, and serves as a power source supplied to the motor 170 and the like. Used with 100. In this embodiment, since it is assumed that the fuel cell stack 100 is operated and controlled (normal control) in a power generation state corresponding to the depression of the accelerator 180 as will be described later, in the operation stop state of the fuel cell stack 100, 2 The secondary battery 172 supplies the charging power to the motor 170. As the secondary battery 172, for example, a lead-charged battery, a nickel metal hydride battery, a lithium ion battery, or the like can be employed. A capacity detection sensor 176 is connected to the secondary battery 172, and the sensor detects a charging state of the secondary battery 172 and outputs the detected charge amount (battery capacity) to the control device 200.

  The DC / DC converter 174 has a charge / discharge control function for controlling charge / discharge of the secondary battery 172, and controls charge / discharge of the secondary battery 172 in response to a control signal from the control device 200. In addition, the DC / DC converter 174 performs the extraction of the generated power of the fuel cell stack 100 and the stored power of the secondary battery 172 and the application of the voltage to the motor 170 under the control of the control device 200, The voltage level applied to the motor 170 is variably adjusted.

  The control device 200 is configured by a so-called microcomputer having a CPU, a ROM, a RAM and the like for executing logical operations, and receives various sensor inputs from the accelerator 180 and controls various controls of the fuel cell vehicle 20. For example, the control device 200 obtains the required power (required load) to the motor 170 according to the operation state of the accelerator 180, so that the required power can be obtained by the power generation of the fuel cell stack 100, or the secondary battery 172 Electric power is supplied to the motor 170 while controlling the power generation of the fuel cell stack 100 and controlling the output of the generated power from the stack so as to cover the charging power or both. When the required load on the motor 170 is obtained by the power generation of the fuel cell stack 100, the control device 200 determines the gas supply amount (gas flow rate) in the hydrogen gas supply system 120 and the air supply system 140 to meet the required load. Control gas pressure (normal control). Further, the control device 200 controls the DC / DC converter 174 according to the required power to the motor 170.

  In addition, the control device 200 includes a vehicle speed detected by the vehicle speed sensor 182, an outside air temperature detected by the outside air temperature sensor 184, a hydrogen gas flow rate detected by the flow sensor 128 in the hydrogen gas supply system 120, and a flow rate sensor in the air supply system 140. The air flow rate detected by 147, the battery capacity (hereinafter referred to as SOC) of the secondary battery 172 detected by the capacity detection sensor 176, etc. are input as control parameters for performing the above-described control.

  Next, power generation control of the fuel cell stack 100 performed by the control device 200 of the fuel cell-equipped vehicle 20 having the above-described configuration in a transient state of required load fluctuation will be described. Since the transient state of the required load fluctuation is divided into an increase transient state of the required load and a transient state of reduction, first, control under the increase transient state of the required load will be described. FIG. 2 is a flowchart showing a control procedure in the situation where the required load increases in the power generation control of the fuel cell stack 100 under the condition where the required load fluctuates. The control under the situation of the required load reduction transition will be described later with reference to FIG.

  When the fuel cell system 30 is activated, the control device 200 normally executes normal operation control for controlling the power generation of the fuel cell stack 100 based on a drive request (required load) from the driver to the vehicle 20 equipped with the fuel cell. Yes. The drive request from the driver to the fuel cell-equipped vehicle 20 at this time is acquired as the required power Pt (required load) from the amount of stepping operation of the accelerator 180 by the driver, the stepping speed, and the like. In order to obtain the required power Pt, the control device 200 refers to the hydrogen gas and air gas flow rates and gas pressures as described above, referring to the IV characteristics, IP characteristics, etc. of the fuel cell. The hydrogen gas and air are supplied to the fuel cell stack 100 at the calculated gas flow rate and gas pressure. While performing such normal power generation control, the control device 200 repeatedly executes the power generation control of the fuel cell stack 100 under the condition of fluctuation of the required load shown in FIG. In the power generation control of FIG. 2, first, the control device 200 reads a stepping operation state such as a stepping operation amount and a stepping speed of the accelerator 180 (see FIG. 1) from an accelerator sensor (not shown), and based on the sensor output, The required load is acquired (step S100).

  Next, the control device 200 determines whether or not the current load request status is a transient state of load increase / decrease from the acquired transition of the required load (step S110). If it is determined that there is not, the process is temporarily terminated. Therefore, in this case, normal power generation control is performed without being affected by the control of FIG.

  Since the transient state of the load fluctuation is either the transient situation of the load increase or the transient situation of the load reduction, if the control device 200 determines that the load is increasing or decreasing in step S110, the load transient state is changed. Depending on the type, the processing after step S120 in FIG. 2 or the processing after step S200 in FIG. If it is determined in step S110 that the load increase is in a transient state, the control device 200 acquires the coolant temperature of the cooling system 160 including the fuel cell stack 100 in the path from the temperature sensor 166 (see FIG. 1) in step S120. The acquired cooling water temperature is compared with the reference temperature α (step S130). Since the coolant temperature has a correlation with the temperature of the fuel cell stack 100, that is, the temperature of the electrolyte membrane 101 in the MEA (see FIG. 1), in step S130, the temperature of the MEA is compared with the reference temperature α. In the present embodiment, the reference temperature α is set to a temperature lower than the MEA appropriate temperature (for example, 80 ° C.) that is assumed to be the temperature before the fuel cell stack 100 is warmed up and the MEA is in a proper wet state. The temperature (for example, 40 ° C.), which tends to be manifested when over-humid, was used. Therefore, if an affirmative determination is made in step S130, it is assumed that the MEA is excessively wet because the cooling water temperature is low. Therefore, in order to optimize this excessive wetness, the control device 200 performs the excessive increase in step S140. The process proceeds to the first wet recovery process. The first process of recovery from overwetting is a process that brings about a gas supply situation useful for optimizing overwetting at the anode 102 and the cathode 103 in the MEA of the fuel cell stack 100, and details thereof will be described later.

  On the other hand, if a negative determination is made in step S130, the control device 200 compares the coolant temperature acquired in step S120 with the reference temperature β (step S150). In the present embodiment, the reference temperature β is set to an appropriate MEA temperature (for example, 80 ° C.) assuming that the MEA is in a proper wet state, and the cooling water temperature, that is, the temperature of the MEA is increased to exceed the reference temperature β. For example, it is assumed that the MEA is overdried. If a negative determination is made in step S150, coupled with a negative determination in step S130, the cooling water temperature is within the temperature range assuming that the MEA is in a proper wet state. Is temporarily useless. If an affirmative determination is made in step S150, it is assumed that the MEA overdrying may have occurred because the cooling water temperature is high. Therefore, in order to optimize the overdrying, the control device 200 performs the overdriving in step S160. The process proceeds to the drying recovery first process. The first process of recovery from overdrying is a process that brings about a gas supply situation useful for optimizing overdrying at the anode 102 and the cathode 103 in the MEA of the fuel cell stack 100, and details thereof will be described later.

  Here, the first process of overwetting recovery in step S140 following the affirmative determination in step S130 will be described. FIG. 3 is a flowchart showing details of the first process of overwetting recovery under a situation where the required load increases transiently, and FIG. 4 is an explanatory diagram for explaining the contents of the determination process in the first process of overwetting recovery. As shown in FIG. 3, in the first overhumidity recovery process, the control device 200 again compares the coolant temperature with the reference temperature α (step S142). This temperature comparison is for determining how much the coolant temperature deviates from the reference temperature α to the low temperature side.

  In step S142, as shown in FIG. 4, when it is determined that the cooling water temperature has deviated to a low temperature side lower than the reference temperature α by a predetermined temperature range α0 or more, the cooling water temperature is higher than the reference temperature α. Since it is low, it is assumed that MEA overwetting is also significant. Therefore, the control apparatus 200 is beneficial for the optimization of overwetting by supplying both the gas supply to the anode 102 and the gas supply to the cathode 103 in the MEA in order to shift the overwetting of the MEA to the appropriate wetness side with higher effectiveness. Control is performed simultaneously and in parallel so as to achieve a correct gas supply (step S144). FIG. 5 is an explanatory diagram schematically illustrating the state of gas supply provided in the first process of recovery from overhumidity under the condition of increase in demand load, and FIG. It is explanatory drawing which shows roughly the mode of the overwetting optimization obtained by 1 process. FIG. 5 shows that the required load increases rapidly at a certain time (hereinafter referred to as start time ts), and reaches a gas supply at a gas flow rate and gas pressure corresponding to the required load at a time after a predetermined time (hereinafter referred to as end time tm). The gas supply status and the gas flow rate transition and gas pressure transition on the cathode side and the anode side under an increasing transient state of the load request from the start time ts to the end time tm are shown.

  For the proper transition of the MEA overwetting, it is beneficial to increase the moisture removal of the generated water at the cathode 103, and at the anode 102 to the air inlet side at the cathode where the electrochemical reaction proceeds actively. It is beneficial to retain moisture to suppress the moisture transport. The increase in moisture removal at the cathode 103 is due to an increase in direct moisture removal due to an increase in the gas flow rate of air and an increase in gas pressure during air supply, in other words, before the transient increase in required load. This is caused by an increase in volume flow rate by maintaining a low gas pressure. Moisture retention at the anode 102 is to avoid an increase in the gas flow rate of hydrogen gas, in other words, to reduce direct moisture removal by maintaining a low gas flow rate before a transient increase in required load, and a gas pressure at the time of hydrogen gas supply Occurs due to volumetric flow reduction due to an increase in.

  Therefore, in step S144, as shown in FIG. 5, the required load increases with respect to the change timing (start time ts) of the gas flow rate when the air is supplied to the cathode 103 as the required load increases. The timing of the gas pressure increase change due to is shifted to the delay side until the delay time ta. By doing so, the control device 200 performs the increase control of the gas flow rate prior to the increase control of the gas pressure when supplying the air to the cathode 103. Such an increase control of the gas flow rate is brought about by the drive control of the compressor 130 (see FIG. 1) by the control device 200, and the delay of the increase of the gas pressure and the subsequent increase control are the drive control of the pressure regulating valve 145 by the control device 200. Brought in. The device control on the cathode side is the same in the recovery process described later. Then, in the cathode 103, as shown in FIG. 6, the volumetric flow rate by increasing the direct moisture removal by increasing the gas flow rate and maintaining the low gas pressure before the demand load increase transient (before the start time ts). The increase causes an increase in moisture removal.

  Further, in step S144, as shown in FIG. 5, the required load increases with respect to the change timing (start time ts) of the gas pressure when the hydrogen gas is supplied to the anode 102 due to the increase in the required load. The timing of the increase change of the gas flow rate accompanying this is shifted to the delay side until the delay time ta. By doing so, the control device 200 performs an increase control of the gas pressure prior to the gas flow rate increase control when supplying the hydrogen gas to the anode 102. Such increase control of the gas pressure is brought about by the drive control of the pressure reducing valve 125 (see FIG. 1) by the control device 200. The delay of the increase of the gas flow rate and the subsequent increase control are driven by the control device 200 to drive the hydrogen supply device 126. Brought in control. The device control on the anode side is the same in the recovery process described later. Then, in the anode 102, as shown in FIG. 6, by reducing the volume flow rate by increasing the gas pressure of hydrogen gas and reducing direct moisture removal by maintaining the low gas flow rate before the increase transient of the required load, Water transport to the cathode air inlet is reduced and moisture retention occurs. Moreover, in step S144, a gas supply situation useful for the above-described proper transition of overwetting is brought about at the anode 102 and the cathode 103 at the same time, and then this routine is terminated.

  In step S142 described above, as shown in FIG. 4, when it is determined that the cooling water temperature has deviated to a lower temperature side than the reference temperature α but the gap is small, the MEA is overwetting, but the MEA is overwetting. It is assumed that the degree is not so great. Therefore, the control device 200 executes the gas supply useful for the above-described proper overwetting by selecting either the anode 102 or the cathode 103 in order to shift such overwetting of the MEA to the appropriate wetness side ( Step S146), this routine is once ended. In the present embodiment, the gas supply described above at the cathode 103 is executed with priority given to increasing the amount of moisture removed at the cathode 103.

  As described above, in performing the increase control of the gas flow rate at the time of supplying the air for the proper wetness transition of the MEA, as shown in FIG. 5, the control device 200 controls the gas flow rate from the start time ts at the cathode 103. The increase is such that the flow rate increase is greater than the increase in gas flow rate that accompanies an increase in required load when the wet state of the MEA is appropriate. Such an increase adjustment of the gas flow rate is more effective for the proper transition of the MEA overwetting because the direct moisture removal due to the increase of the gas flow rate becomes more remarkable at the cathode 103. In addition, in performing the increase control of the gas pressure at the time of supplying the hydrogen gas for the proper wetting of the MEA humidification, the control device 200 increases the gas pressure from the start time ts at the anode 102 as shown in FIG. The pressure increase is greater than the increase in gas pressure that accompanies an increase in required load when the wet state of the MEA is appropriate. Such an increase adjustment of the gas pressure makes the volume flow rate decrease due to the increase of the gas pressure more remarkable at the anode 102, which is beneficial for the proper transition of the MEA overwetting. That is, the control device 200 adjusts the gas flow rate increase for the air supplied to the cathode 103 and adjusts the hydrogen gas supplied to the anode 102 as an optimization adjustment that can shift the overwetting of the MEA to the appropriate wetness side. Then, increase gas pressure is adjusted.

  Next, the overdrying recovery first process in step S160 following the affirmative determination in step S150 of FIG. 2 will be described. FIG. 7 is a flowchart showing details of the first process of recovery from overdrying in a situation where the required load increases transiently, and FIG. 8 is an explanatory diagram for explaining the contents of the determination process in the first process of recovery from overdrying. As shown in FIG. 7, in the overdrying recovery first process, the control device 200 again compares the coolant temperature with the reference temperature β (step S162). This temperature comparison is for determining how much the coolant temperature deviates from the reference temperature β to the high temperature side.

  In this step S162, as shown in FIG. 8, when it is determined that the cooling water temperature has deviated to a high temperature side higher than the reference temperature β by a predetermined temperature range β0, the cooling water temperature is higher than the reference temperature β. It is assumed that the MEA is excessively dry due to its high value. Therefore, the control device 200 is beneficial for the proper overdrying of the gas supply to the anode 102 and the gas supply to the cathode 103 in the MEA in order to shift the overdrying of the MEA to the wetness appropriate side with higher effectiveness. Control is performed simultaneously and in parallel so as to achieve a correct gas supply (step S164). FIG. 9 is an explanatory diagram schematically illustrating the state of gas supply provided in the first process of recovery from overdrying under the condition of increase in required load, and FIG. 10 is a diagram illustrating recovery from overdrying under the condition of increase in required load. It is explanatory drawing which shows roughly the mode of the overdrying optimization obtained by 1 process. Even in FIG. 8, as in FIG. 5, the required load increases rapidly at the start time ts, and the gas supply situation reaches the gas supply at the gas flow rate and gas pressure corresponding to the required load at the end time tm, and the start time ts. 3 shows the gas flow rate transition and gas pressure transition on the cathode side / anode side under the increasing transient situation of the load demand from to the end time tm.

  For proper transition of MEA overdrying, it is beneficial to reduce the moisture removal of the generated water at the cathode 103, and at the anode 102 to the air inlet side at the cathode where the electrochemical reaction proceeds actively. It is beneficial to increase the amount of water transport and to move the water from the anode side to the cathode side. The reduction of moisture removal at the cathode 103 avoids an increase in the gas flow rate during air supply, in other words, a reduction in direct moisture removal by maintaining a low gas flow rate before the transient increase in required load, and air Occurs due to volumetric flow reduction due to increased gas pressure during supply. The increase in water conveyance and water movement described above at the anode 102 is due to an increase in direct moisture removal due to an increase in the gas flow rate of the hydrogen gas supply, avoiding an increase in gas pressure, in other words, before a transient increase in required load. This is caused by an increase in volume flow rate by maintaining a low gas pressure.

  Therefore, in step S164, as shown in FIG. 9, the required load increases with respect to the change timing (start time ts) of the gas pressure when the air is supplied to the cathode 103 as the required load increases. The timing of the increase change of the gas flow rate accompanying this is shifted to the delay side until the delay time ta. By doing so, the control device 200 performs the increase control of the gas pressure prior to the increase control of the gas flow rate when supplying the air to the cathode 103. Then, in the cathode 103, as shown in FIG. 10, the reduction of direct moisture removal by maintaining the low gas flow rate before the increase in required load (before the start time ts) and the volume flow rate by increasing the gas pressure are achieved. Reduction reduces moisture removal.

  In step S164, as shown in FIG. 9, the required load increases with respect to the change timing (start time ts) of the gas flow rate when the hydrogen gas is supplied to the anode 102 due to the increase in the required load. The timing of the gas pressure increase change due to is shifted to the delay side until the delay time ta. By doing so, the control device 200 performs the increase control of the gas flow rate prior to the gas pressure increase control when supplying the hydrogen gas to the anode 102. Then, in the anode 102, as shown in FIG. 10, by increasing the water conveyance due to the increase in the gas flow rate, and by increasing the volume flow rate due to the low gas pressure maintenance before the demand load increase transient (before the start time ts), Increase in water transfer from the cathode to the cathode occurs. Moreover, in step S164, the gas supply situation useful for the above-described proper side transition of the overdrying is simultaneously caused in the anode 102 and the cathode 103, and then this routine is terminated.

  In step S162 described above, as shown in FIG. 8, when it is determined that the cooling water temperature has deviated higher than the reference temperature β but the gap is small, the MEA is overdried but not overdried. It is assumed that the degree is not so great. Therefore, the control device 200 selects either the anode 102 or the cathode 103 and executes gas supply useful for optimizing the overdrying in order to shift the overdrying of the MEA to the proper wetness side ( Step S166), this routine is finished once. In the present embodiment, the above-described gas supply at the cathode 103 is executed with priority given to reducing moisture removal at the cathode 103.

  As described above, in performing the increase control of the gas pressure at the time of supplying the air for the proper wet and dry transition of the MEA, as shown in FIG. 9, the control device 200 controls the gas pressure from the start time ts at the cathode 103. The increase is such that the gas pressure is greater than the increase in gas pressure that accompanies the increase in required load when the wet state of the MEA is appropriate. Such an increase adjustment of the gas pressure is coupled with gas supply at a low gas flow rate before the load change at the cathode 103, and moisture removal is further suppressed, which is beneficial for proper transition of MEA overdrying. Further, in performing the increase control of the gas flow rate at the time of supplying the hydrogen gas for the proper wetness transition of the MEA addition / drying, the control device 200 increases the gas flow rate from the start time ts in the anode 102 as shown in FIG. The gas flow rate is set to be larger than the gas flow rate increase performed with the increase in the required load when the wet state of the MEA is appropriate. Such an increase adjustment of the gas flow rate is beneficial for the proper transition of the MEA overdrying in the anode 102 because water conveyance due to the gas flow rate increase and the accompanying water movement to the cathode side become more remarkable. That is, the control device 200 adjusts the gas pressure for the air supplied to the cathode 103 and adjusts the hydrogen pressure to be supplied to the anode 102 as an adjustment adjustment that can shift the over-drying of the MEA to the appropriate wetness side. , Increase gas flow rate adjustment.

  Next, the control when it is determined in step S110 of FIG. 2 that the load reduction is in a transient state will be described. FIG. 11 is a flowchart showing a control procedure of power generation control of the fuel cell stack 100 under the condition of reduction of required load. Following the determination of the required load reduction transient in step S110, the control device 200 obtains the coolant temperature (step S200) and compares the acquired coolant temperature (step S200) as in steps S120 to S130 described above. S2100). If the control device 200 makes an affirmative determination in step S210, it is assumed that the MEA is excessively wet because the cooling water temperature is low. Therefore, in order to optimize the excessive wetness, the excessive wetness recovery in step S220 is performed. The process proceeds to the second process. This overwetting recovery second process is a process that brings about a gas supply situation that is beneficial for optimizing overwetting at the anode 102 and the cathode 103 in the MEA of the fuel cell stack 100, as in the first process described above. .

  On the other hand, if a negative determination is made in step S210, the control device 200 compares the coolant temperature acquired in step S200 with the reference temperature β (step S230), and if a negative determination is made in step S230, a negative determination in step S210. Since the cooling water temperature is within the temperature range assuming that the MEA is in a proper wet state, the process is temporarily terminated assuming that the optimization of overwetting and overdrying is unnecessary. If an affirmative determination is made in step S230, it is assumed that the MEA overdrying may have occurred because the cooling water temperature is high. Therefore, in order to optimize the overdrying, the control device 200 performs the overdriving in step S240. The process proceeds to the drying recovery second process. This overdrying recovery second process is a process that brings about a gas supply situation useful for optimizing overdrying at the anode 102 and the cathode 103 in the MEA of the fuel cell stack 100, as in the first process described above. .

  Here, the second process of overwetting recovery in step S220 following the affirmative determination in step S210 will be described. FIG. 12 is a flowchart showing the details of the second process of overwetting recovery under the transient state of required load reduction. As shown in FIG. 12, in the overhumidity optimization second process, the control device 200 again compares the cooling water temperature with the reference temperature α (step S222) as in step S142 described above, and lowers the temperature from the reference temperature α. The deviation degree of the cooling water temperature to the side is determined.

  In step S222, as shown in FIG. 4, when it is determined that the cooling water temperature has deviated to a low temperature side lower than the reference temperature α by a predetermined temperature range α0 or more, the cooling water temperature is higher than the reference temperature α. Since it is low, it is assumed that MEA overwetting is also significant. Therefore, the control apparatus 200 is beneficial for the optimization of overwetting by supplying both the gas supply to the anode 102 and the gas supply to the cathode 103 in the MEA in order to shift the overwetting of the MEA to the appropriate wetness side with higher effectiveness. Control is performed simultaneously and in parallel so that a correct gas supply is obtained (step S224). FIG. 13 is an explanatory diagram schematically illustrating the state of gas supply brought about by the second process of over-humidity recovery under a transient state of required load reduction, and FIG. It is explanatory drawing which shows roughly the mode of the overwetting optimization obtained by 2 processes. In FIG. 13, the required load sharply decreases at the start time ts, and the gas supply state reaches the gas supply at the gas flow rate and the gas pressure corresponding to the required load at the end time tm, and from the start time ts to the end time tm. This shows the gas flow rate transition and gas pressure transition on the cathode side and anode side under the transient condition of reducing the load demand.

  As described above, an increase in the moisture removal of the produced water is beneficial in the cathode 103, and the anode 102 has an active electrochemical reaction in the cathode. Moisture retention that suppresses moisture transport to the air inlet side is beneficial. The increase in moisture removal at the cathode 103 during the demand load reduction transient avoids the reduction of the gas flow rate when supplying air, in other words, the direct moisture retention by maintaining the high gas flow rate before the demand load reduction transient. This is caused by an increase in volume and an increase in volumetric flow rate due to a reduction in air gas pressure. The moisture retention at the anode 102 during the transition of the required load is reduced by reducing the direct moisture removal by reducing the gas flow rate of the hydrogen gas, and avoiding the reduction of the gas pressure when supplying the hydrogen gas, in other words, the required load. This occurs due to volumetric flow reduction by maintaining high gas pressure before the transition.

  For this reason, in step S224, as shown in FIG. 13, the required load is reduced with respect to the change timing (start time ts) of the gas pressure when the air is supplied to the cathode 103 due to the reduction of the required load. The timing of the gas flow reduction change accompanying this is shifted to the delay side until the delay time ta. By doing so, the control device 200 performs the gas pressure reduction control prior to the gas flow rate reduction control when supplying air to the cathode 103. In the cathode 103, as shown in FIG. 14, an increase in volumetric flow rate due to a reduction in gas pressure and an increase in direct moisture removal due to the maintenance of a high gas flow rate before the required load reduction transient (before the start time ts). As a result, moisture removal increases.

  Further, in step S224, as shown in FIG. 13, the required load is reduced with respect to the change timing (start time ts) of the gas flow rate when the hydrogen gas is supplied to the anode 102 due to the reduction of the required load. The timing of the gas pressure reduction change accompanying this is shifted to the delay side until the delay time ta. By doing so, the control apparatus 200 performs the gas flow rate reduction control prior to the gas pressure reduction control when supplying the hydrogen gas to the anode 102. Then, in the anode 102, as shown in FIG. 14, by reducing the direct moisture removal by reducing the gas flow rate of hydrogen gas and by reducing the volume flow rate by maintaining the high gas pressure before the transition of the required load, Water transport to the cathode air inlet is reduced and moisture retention occurs. Moreover, in step S224, a gas supply situation useful for the above-described proper transition of overwetting is brought about at the anode 102 and the cathode 103 at the same time, and then this routine is terminated.

  In step S222 described above, as shown in FIG. 4, when it is determined that the cooling water temperature has deviated to a lower temperature side than the reference temperature α, but the gap is small, the MEA is overwetting, but the MEA is overwetting. It is assumed that the degree is not so great. Therefore, the control device 200 executes the gas supply useful for the above-described proper overwetting by selecting either the anode 102 or the cathode 103 in order to shift such overwetting of the MEA to the appropriate wetness side ( Step S226), this routine is ended once. In the present embodiment, the gas supply described above at the cathode 103 is executed with priority given to increasing the amount of moisture removed at the cathode 103.

  As described above, in performing the reduction control of the gas pressure at the time of supplying the air for the proper wetness transition of the MEA, as shown in FIG. 13, the control device 200 performs the gas pressure from the start time ts at the cathode 103 as shown in FIG. The reduction is made to be a pressure reduction that is greater than the gas pressure reduction that accompanies the reduction of the required load when the wet state of the MEA is appropriate. Such a gas pressure reduction adjustment is beneficial for the proper transition of the MEA overwetting because the cathode 103 is more prone to moisture removal due to an increase in volume flow rate due to gas pressure reduction. In addition, in performing the reduction control of the gas flow rate at the time of supplying the hydrogen gas for the proper wetness transition of the humidification of the MEA, the control device 200 reduces the gas flow rate from the start time ts in the anode 102 as shown in FIG. The flow rate is reduced more than the gas flow rate reduction that accompanies the reduction of the required load when the wet state of the MEA is appropriate. Such adjustment of the gas flow rate reduction makes the reduction of moisture removal due to the gas flow rate reduction more remarkable in the anode 102, and is beneficial for the proper wetting of MEA overwetting. That is, the control device 200 performs gas pressure reduction adjustment for the air supplied to the cathode 103 and the hydrogen gas supplied to the anode 102 as an adjustment adjustment that can shift the overwetting of the MEA to the proper wetness side. Measure gas flow reduction.

  Next, the second process of overdrying recovery in step S240 following the affirmative determination in step S230 of FIG. 11 will be described. FIG. 15 is a flowchart showing the details of the second process of recovery from overdrying under the condition of transient reduction of the required load. As shown in FIG. 15, in the overdrying recovery second process, the control device 200 again compares the cooling water temperature with the reference temperature β (step S <b> 242). This temperature comparison is for determining how much the coolant temperature deviates from the reference temperature β to the high temperature side.

  In this step S242, as shown in FIG. 8, when it is determined that the cooling water temperature has deviated to a higher temperature side that is higher than the reference temperature β by a predetermined temperature range β0, the cooling water temperature is higher than the reference temperature β. It is assumed that the MEA is excessively dry due to its high value. Therefore, the control device 200 is beneficial for the proper overdrying of the gas supply to the anode 102 and the gas supply to the cathode 103 in the MEA in order to shift the overdrying of the MEA to the wetness appropriate side with higher effectiveness. Control is performed simultaneously and in parallel so as to achieve a correct gas supply (step S244). FIG. 16 is an explanatory diagram schematically illustrating the state of gas supply brought about by the second process of recovery from excessive drying under the transient condition of the required load, and FIG. It is explanatory drawing which shows roughly the mode of the overdrying optimization obtained by 2 processes. Also in FIG. 16, the required load is suddenly reduced at the start time ts, and the gas supply situation reaches the gas supply at the gas flow rate and gas pressure corresponding to the required load at the end time tm, and from the start time ts to the end time tm. This shows the gas flow rate transition and gas pressure transition on the cathode side and anode side under the transient condition of reducing the load demand.

  As described above, it is beneficial to reduce the moisture removal of the generated water at the cathode 103, and the anode 102 has an active electrochemical reaction at the cathode where the progress of the electrochemical reaction is active. Increasing the amount of water transport to the air inlet side and the accompanying water movement from the anode side to the cathode side is beneficial. The reduction of moisture removal at the cathode 103 is achieved by directly reducing moisture removal by reducing the gas flow rate at the time of air supply and reducing the gas pressure at the time of air supply, in other words, reducing the required load. Occurs due to volumetric flow reduction by maintaining high gas pressure before the transient. The increase in water conveyance and water movement described above at the anode 102 is due to an increase in volumetric flow rate due to a reduction in gas pressure when hydrogen gas is supplied, avoidance of gas flow reduction, in other words, reduction of required load, and maintenance of a high gas flow rate before a transient. This is caused by an increase in direct moisture removal by

  For this reason, in step S244, as shown in FIG. 16, the required load is reduced with respect to the change timing (start time ts) of the gas flow rate when the air is supplied to the cathode 103 due to the reduction of the required load. The timing of the gas pressure reduction change accompanying this is shifted to the delay side until the delay time ta. By doing so, the control device 200 performs the gas flow rate reduction control prior to the gas pressure reduction control when supplying the air to the cathode 103. Then, in the cathode 103, as shown in FIG. 17, the volume flow rate by reducing the direct moisture removal by reducing the gas flow rate and maintaining the high gas pressure before the required load reduction transient (before the start time ts). Reduction reduces moisture removal.

  Further, in step S244, as shown in FIG. 16, the required load is reduced with respect to the change timing (start time ts) of the gas pressure when the hydrogen gas is supplied to the anode 102 due to the reduction of the required load. The timing of the gas flow reduction change accompanying this is shifted to the delay side until the delay time ta. Thus, the control device 200 performs the gas pressure reduction control prior to the gas flow rate reduction control when supplying the hydrogen gas to the anode 102. As shown in FIG. 17, the anode 102 increases the volume flow rate by reducing the gas pressure and increases the water conveyance by maintaining the high gas flow rate before the required load reduction transient (before the start time ts). Increase in water transfer from the cathode to the cathode occurs. In addition, in step S244, a gas supply situation useful for the above-described proper side transition of overdrying is simultaneously provided in the anode 102 and the cathode 103, and then this routine is terminated.

  In step S242 described above, as shown in FIG. 8, when it is determined that the cooling water temperature has deviated to a higher temperature side than the reference temperature β, but the separation is small, the MEA is overdried but overdried. It is assumed that the degree is not so great. Therefore, the control device 200 selects either the anode 102 or the cathode 103 and executes gas supply useful for optimizing the overdrying in order to shift the overdrying of the MEA to the proper wetness side ( Step S246), this routine is ended once. In the present embodiment, the above-described gas supply at the cathode 103 is executed with priority given to reducing moisture removal at the cathode 103.

  As described above, in performing the reduction control of the gas flow rate at the time of air supply for the proper wet and dry transition of the MEA, as shown in FIG. 16, the control device 200 performs the gas flow rate from the start time ts at the cathode 103. The reduction is performed so that the gas flow rate is smaller than the gas flow rate reduction performed in accordance with the reduction of the required load when the wet state of the MEA is appropriate. Such reduction adjustment of the gas flow rate is coupled with gas supply at a high gas pressure before the load fluctuation at the cathode 103, and moisture removal is further suppressed, which is beneficial for proper transition of MEA overdrying. In addition, when performing control to reduce the gas pressure when supplying hydrogen gas for the proper transition of wetness of MEA, the controller 200 reduces the gas pressure from the start time ts at the anode 102 as shown in FIG. The gas pressure is set to be smaller than the gas pressure reduction performed when the required load is reduced when the wet state of the MEA is appropriate. Such gas pressure reduction adjustment, combined with the gas supply at the high gas flow rate before the load change, makes the water conveyance and the water movement to the cathode side more conspicuous in the anode 102, and the MEA overdrying proper wetness Useful for transition. That is, the control device 200 adjusts the gas flow rate reduction for the air supplied to the cathode 103 and adjusts the hydrogen gas supplied to the anode 102 as an adjustment adjustment that can shift the over-drying of the MEA to an appropriate wetness side. Measure gas pressure reduction.

  As described above, the fuel cell system 30 mounted on the fuel cell vehicle 20 of the present embodiment determines whether the wet state of the fuel cell stack 100 deviates from the proper wet state in a transient state of load fluctuation. (Step S110). Then, the gas flow rate change or the gas pressure change on the side useful for shifting the wet state to the proper wet state is performed in any of the transient states of the increase transient and the decrease of the load fluctuation. In addition, if the control useful for shifting the wet state to the proper wet state is the gas flow rate change control, this gas flow rate change is performed in accordance with the load fluctuation situation when supplying the gas accompanying the load fluctuation, Delayed by this change, the gas pressure is changed (steps S140, 160, 220, 240, FIG. 5, FIG. 9, FIG. 13, FIG. 16). If the gas pressure change control is useful for shifting the wet state to the proper wet state, this gas pressure change is performed in accordance with the load change situation when the gas is supplied with the load change, and this change is delayed. Then, the gas flow rate is changed (steps S140, 160, 220, 240, FIG. 5, FIG. 9, FIG. 13, FIG. 16).

  Due to such a shift in the change timing (FIGS. 5, 9, 13, and 16), during the change delay, the gas pressure when the gas flow rate is changed in accordance with the load fluctuation situation or the gas pressure change is changed. When the gas flow is performed according to the load fluctuation, the gas flow rate is maintained in the condition before the load fluctuation. The state of the gas flow rate or gas pressure before the load change maintained in this way becomes a state of reduction or increase of the gas flow rate or reduction or increase of the gas pressure with respect to the gas flow rate or gas pressure corresponding to the change of the load request. (FIGS. 5, 9, 13, and 16). Therefore, the gas supply state brought about by the gas flow rate or gas pressure useful for shifting the wet state to the proper wet state and the gas flow rate or gas pressure in which the state before the load change is maintained is, for example, the wet state. Because it is over-dried, it is useful to reduce the moisture removal that is beneficial for shifting it to the proper side, the situation of gas flow reduction and gas pressure increase that brings moisture retention, or the gas flow increase that is beneficial for proper transition Various gas flow rates and pressure conditions such as a gas pressure reduction situation (FIGS. 10 and 17), and such a gas supply situation is reliably realized in a transient load change. If the wet state is excessively wet, the situation of gas flow rate increase and gas pressure reduction leading to an increase in moisture removal that is beneficial for shifting this to the proper side, or gas flow rate reduction beneficial for proper transition Various gas flow rate and pressure situations such as the situation of an increase in gas pressure (FIGS. 6 and 14) are reliably realized in the transition of the load fluctuation. As a result, according to the fuel cell system 30 mounted on the fuel cell-equipped vehicle 20 of this embodiment, the fuel cell stack 100, more specifically, the MEA electrolyte membrane 101 can be effectively prevented from being excessively dried or excessively wet during the load fluctuation transition period. The output can be improved and the output can be reliably stabilized.

  The fuel cell system 30 mounted on the fuel cell-equipped vehicle 20 according to the present embodiment has an increase control of the gas flow rate at the time of air supply on the cathode side in order to achieve a proper transition of humidification in a transient state where the required load increases. Increase control of gas pressure at the time of hydrogen gas supply on the anode side (FIG. 5), and increase control of gas pressure at the time of air supply on the cathode side and control on the anode side for proper wetting of drying and drying Increase control of the gas flow rate during the supply of hydrogen gas is performed (FIG. 9). Then, these increase controls are adjusted so that the flow rate increase and the pressure increase are larger than the gas flow rate increase and the gas pressure increase that accompany the increase in the required load when the wet state of the MEA is appropriate. In this way, the respective gas supply statuses of air and hydrogen gas to the fuel cell stack 100 can effectively reduce moisture retention and moisture retention, or increase moisture removal, which are appropriately beneficial in a wet state. The situation can be such that the gas flow rate is increased or the gas pressure is increased (FIGS. 6 and 10), and such a situation can be reliably realized. As a result, according to the fuel cell system 30 mounted on the fuel cell-equipped vehicle 20 of the present embodiment, the fuel cell stack 100, more specifically, the MEA electrolyte membrane 101 is excessively dried or excessively wet during the transitional period of increase in load. The effectiveness of the suppression can be further increased, and an output corresponding to the increased load can be reliably and stably obtained.

  The fuel cell system 30 mounted on the fuel cell-equipped vehicle 20 according to the present embodiment has a gas pressure reduction control at the time of air supply on the cathode side in order to achieve a proper transition of humidification in a transient state where the required load is reduced. Control of gas flow reduction during the supply of hydrogen gas on the anode side (Fig. 13), and control of gas flow reduction during air supply on the cathode side and control on the anode side for proper wetting and drying. Gas pressure reduction control during supply of hydrogen gas is performed (FIG. 16). Then, these reduction controls are adjusted so that the flow rate reduction and pressure reduction are greater than the gas flow rate reduction and gas pressure reduction performed in accordance with the reduction of the required load when the wet state of the MEA is appropriate. In this way, the respective gas supply statuses of air and hydrogen gas to the fuel cell stack 100 can effectively reduce moisture retention and moisture retention, or increase moisture removal, which are appropriately beneficial in a wet state. The situation can be such that the gas flow rate is reduced or the gas pressure is reduced (FIGS. 14 and 17). As a result, according to the fuel cell system 30 mounted on the fuel cell-equipped vehicle 20 of the present embodiment, the fuel cell stack 100, more specifically, the MEA electrolyte membrane 101 is excessively dried or excessively wet during the transition period of the load reduction fluctuation. The effectiveness of the suppression can be further increased, and the output corresponding to the reduced load can be reliably and stably obtained.

  Next, another embodiment will be described. FIG. 18 is an explanatory diagram schematically illustrating the gas supply status in the first process of overhumidity recovery performed under the condition of increasing transient load demand in the fuel cell stack 100 of the second embodiment, and FIG. 19 is a diagram illustrating the second embodiment. It is explanatory drawing which illustrates schematically the gas supply condition in the overdrying recovery 1st process made in the condition of the increase transient of a required load in the fuel cell stack 100 of an example. In this embodiment, the proper state of wetness of MEA overwetting under the condition of increase in demand load transients is that the wet state is appropriate for the increase in gas flow rate on the cathode side and the increase in gas pressure on the anode side. In the same manner as in this case, the change timing was shifted to the delay side with respect to the increase change of the gas pressure on the cathode side and the gas flow rate on the anode side after performing in accordance with the increase in the required load (FIG. 18). In addition, the appropriate wet transition of MEA overdrying under the condition of transient increase in required load includes an increase in gas pressure on the cathode side and an increase in gas flow rate on the anode side when the wet state is appropriate. Similarly, after changing in accordance with the increase in the required load, the change timing of the increase in the cathode gas flow rate and the anode gas pressure was shifted to the delay side (FIG. 19). As described above, an increase in gas flow rate on the cathode side and an increase in gas pressure on the anode side are beneficial for the proper transition of overwetting of the MEA under the transient condition of increase in demand load. In a load transient, these are usually controlled to increase as shown. As described above, an increase in the gas pressure on the cathode side and an increase in the gas flow rate on the anode side are beneficial for the proper transition of the over-drying of the MEA under the transient condition of the increase in the required load. In the increase transient, these are usually controlled to increase as shown. In this embodiment, the low gas pressure is maintained on the cathode side and the stationary gas flow rate is maintained on the anode side before the required load is increased by shifting the gas flow rate increasing timing and the gas pressure increasing timing as shown in the figure. Plan. Therefore, also by this embodiment, the effect approximated to the effect mentioned above can be show | played.

  FIG. 20 is an explanatory diagram showing a change in the processing content of the first overdrying recovery process and a transition of the gas supply status associated therewith under a situation where the required load increases transiently in the previous embodiment. In this embodiment, when executing the first process of recovery from overdrying in step S166, when the gas flow rate increase control for optimizing the wetness at the anode 102 is performed, the increase adjustment target value is set to the value when the wet state is appropriate. The gas flow rate increase was temporarily increased with respect to the increase adjustment target value. For example, an adjustment target value that is, for example, about 20% to 30% larger than the increase adjustment target value for increasing the gas flow rate when the wet state is appropriate, and the period of such a large target value corresponds to an increase in required load. For example, about 1 to 2 sec is secured just before the end time tm of the increase control in the increased gas flow rate period. FIG. 21 is an explanatory diagram showing advantages when the gas flow rate increase control for optimizing wetness is temporarily set to a large increase adjustment target value. In the comparative example in FIG. 21, when the MEA is overdried under the condition of an increase in the required load, the gas supply is performed so that the increased gas flow rate target value that matches the increase in the required load increases as the required load increases. Controlled. Note that there is no deviation in the change timing of the gas flow rate increase and the gas pressure increase.

  FIG. 21 shows the cell voltage transition when the fuel cell stack 100 is in a power generation state with a low current density and when the fuel cell stack 100 transitions to a power generation state with a high current density as the required load increases rapidly. From FIG. 21, in this embodiment, the wet optimization from overdrying in the transient state of the required load increased more reliably, and the output can be improved. Such an event can be explained as follows. Hydrogen gas is supplied to the fuel cell stack 100 at a gas flow rate that temporarily becomes an increase adjustment target value that is larger than the increase adjustment target value when the gas flow rate is increased in response to an increasing load. This further increase in the gas flow rate, during the transitional period of fluctuations in the load increase, makes the reduction of moisture removal and moisture retention, which are beneficial for optimizing the wetness of the overdrying on the anode side, becoming noticeable. Water movement is also activated. Therefore, the fuel cell stack 100, specifically, the MEA electrolyte membrane 101 in an excessively transitional period of required load, has been properly dried, and the output corresponding to the increased load can be stably obtained.

  FIG. 22 is an explanatory diagram showing another embodiment in which the gas flow rate increase control for optimizing wetness is temporarily set to a large increase adjustment target value. As shown in the drawing, in this embodiment, the increase adjustment target value of the gas flow rate increase control for optimizing the wetness in executing the first process of recovery from overdrying in step S166 is set to the increase of the gas flow rate when the wet state is appropriate. The increase adjustment target value is temporarily increased before the increase control end time tm. Even in this case, the effect shown in FIG. 21 can be obtained.

  FIG. 23 is an explanatory diagram showing a change in the processing content of the second overdrying recovery second process under the transitional state of reduction of the required load in the previous embodiment and the transition of the gas supply status associated therewith. In this embodiment, when executing the second process of recovery from overdrying in step S246, the reduction adjustment target value is set to the value when the wet state is appropriate in the gas flow rate reduction control for optimizing the wetness at the cathode 103. The gas flow rate reduction was temporarily reduced with respect to the reduction adjustment target value. For example, the adjustment target value is reduced by about 20 to 30%, for example, with respect to the reduction adjustment target value for reducing the gas flow rate when the wet state is appropriate. For example, about 1 to 2 sec is secured before the end time tm of the reduction control in the reduced gas flow rate period. Note that it may be ensured just before the end time tm. Even in this way, further reduction in gas flow will significantly reduce moisture removal, which is beneficial to optimizing over-drying on the cathode side, during the transitional period of load reduction. As a result, the fuel cell stack 100 in the transition period of load reduction, more specifically, the MEA electrolyte membrane 101 has been properly dried and wet, and an output corresponding to the increase and reduction can be stably obtained.

  As mentioned above, although the embodiment of the present invention has been described in the embodiments, the present invention is not limited to the above-described embodiments and modifications, and can be implemented in various modes without departing from the gist thereof. Is possible.

  For example, following the shift of the change timing of the gas flow rate increase / gas pressure increase in the over-drying or over-humidity optimization in the situation of the increase transient of the required load shown in FIG. 18 and FIG. In order to optimize over-drying or over-wetting under the above conditions, the gas flow rate reduction / gas pressure fixed point change timing may be shifted.

  Further, the increase adjustment target value of the gas flow rate increase control for optimizing the wetness of the overdrying under the transient condition of the increase in the required load shown in FIG. 20 or FIG. Increase of gas pressure increase control for optimizing wetness under the condition of transient increase of demand load instead of temporarily increasing with respect to the increase adjustment target value or in parallel with such increase adjustment control of gas flow rate You may make it perform gas supply control which makes adjustment target value temporarily large with respect to the increase adjustment target value of the gas pressure increase at the time of wet state appropriateness. In addition, the reduction target value of gas reduction adjustment and gas pressure reduction adjustment control for wet optimization under transient conditions of required load reduction, gas flow reduction and gas pressure reduction control reduction when wet condition is appropriate The adjustment target value may be temporarily reduced.

  In each of the embodiments described above, the wet state of the MEA electrolyte membrane 101 in the fuel cell stack 100 is determined based on the coolant temperature, but the wet state may be determined based on the resistance value of the fuel cell stack 100. In this case, if the resistance value exceeds a predetermined upper limit reference resistance value, it is determined that it is overdried, and if the resistance value falls below a predetermined lower limit resistance value, it can be determined that it is excessively wet. The wet state may be determined by other methods without being limited to the resistance value.

  In each of the above-described embodiments, when determining the required load fluctuation transient, the load demand fluctuation transient required for the fuel cell stack 100 may be determined in consideration of the stored power of the secondary battery 172. .

  In addition, in the first embodiment, after determining whether or not the MEA is excessively wet or excessively dried, the level of excessively wet or excessively dry is determined according to the cooling water temperature (step S142: FIG. 4, step S162). : FIG. 8), the gas flow rate and pressure are adjusted to optimize the wet state, but the present invention is not limited to this. For example, if it is determined that the MEA is excessively wet or excessively dried due to the cooling water temperature, the gas flow rate / pressure may be adjusted to optimize the wet state without performing level determination. At this time, the adjustment of the gas flow rate and pressure for optimizing the wet state on the anode side and the cathode side may be performed by either parallel adjustment or selective adjustment.

DESCRIPTION OF SYMBOLS 20 ... Vehicle equipped with fuel cell 22 ... Car body 30 ... Fuel cell system 100 ... Fuel cell stack 101 ... Electrolyte membrane 102 ... Anode 103 ... Cathode 104 ... Anode side gas diffusion layer 105 ... Cathode side gas diffusion layer 106 ... Current sensor 110 ... Hydrogen Gas tank 120 ... Hydrogen gas supply system 121 ... Hydrogen supply path 122 ... Circulation path 123 ... Release path 124 ... Open / close valve 125 ... Pressure reducing valve 126 ... Hydrogen supply equipment 127 ... Circulation pump 128 ... Flow sensor 129 ... Open / close valve 130 ... Compressor 140 ... Air supply system 141 ... Oxygen supply path 142 ... Release path 143 ... Exhaust flow rate adjustment valve 145 ... Pressure adjustment valve 147 ... Flow rate sensor 150 ... Radiator 152 ... Fan 160 ... Cooling system 161 ... Circulation path 162 ... Bypass path 163 ... Three Flow control valve 164 ... circulation pump 166 ... temperature sensor 170 ... motor 172 ... secondary battery 174 ... DC / DC converter 176 ... capacity detection sensor 180 ... accelerator 182 ... vehicle speed sensor 184 ... outside air temperature sensor 200 ... control device FW ... front wheel RW ... Rear wheel ts ... Start time ta ... Delay time tm ... End time

Claims (6)

A fuel cell system,
A fuel cell stack that generates electricity by receiving the supply of the reaction gas; and
A gas supply that includes a gas flow rate and a gas pressure as control parameters based on a load requirement required for the fuel cell stack, and controls the gas supply of the reaction gas to the fuel cell stack with the control parameter based on the load requirement. A control unit;
Based on the load request, a load variation determination unit that determines whether or not the load variation is in a transient state;
A wetness determination unit for determining the wet state of the fuel cell stack,
The gas supply controller is
When the load variation determination unit determines that the load variation is in a transient state, the gas flow rate or gas pressure that contributes to shifting the wet state determined by the wet determination unit to the proper wet state among the control parameters. The timing of changing the other control parameter is shifted to the delay side with respect to the timing of changing one of the control parameters.
Fuel cell system. The fuel cell system according to claim 1,
The gas supply controller is
In changing the one control parameter, the one control parameter is changed to a gas flow rate or a gas pressure that has undergone optimization adjustment that can shift the wet state determined by the wetness determination unit to a proper wetness side. Shift the change timing of the other control parameter, which is the gas flow rate or gas pressure without undergoing the adjustment adjustment, to the delay side with respect to the change timing through the optimization adjustment;
Fuel cell system. The fuel cell system according to claim 2, wherein
The gas supply controller is
When the load fluctuation determining unit determines that the load is in transition, the optimization adjustment is set to increase optimization of the gas flow rate or gas pressure, and the one control is performed to the gas flow rate or gas pressure after the increase optimization adjustment. Change the parameters,
Fuel cell system. The fuel cell system according to claim 3,
The gas supply controller is
The change of the one control parameter to the gas flow rate or the gas pressure that has undergone the increase optimization adjustment is temporarily performed based on the increase adjustment target value based on the load request when the wet determination unit determines that the wetness is appropriate. To achieve a large increase adjustment target value,
Fuel cell system. The fuel cell system according to claim 1,
The gas supply controller is
When the load fluctuation determination unit determines that the load is in a transient state of load reduction, the optimization adjustment is set as a gas flow rate or gas pressure reduction optimization adjustment, and the one control is performed to the gas flow rate or gas pressure after the reduction optimization adjustment. Change the parameters,
Fuel cell system. The fuel cell system according to claim 5, wherein
The gas supply controller is
The change of the one control parameter to the gas flow rate or the gas pressure that has undergone the reduction optimization adjustment is temporarily performed based on the reduction adjustment target value based on the load request in the wet state determined by the wetness determination unit as being wettable. To achieve a low reduction adjustment target value,
Fuel cell system.

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