JP2012169294A - Fuel cell system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce a residual moisture content remaining in a fuel cell when the fuel cell of a fuel cell system is stopped in a specific time zone where, if the fuel cell is stopped in a startup process, residual water would block up an air passage after the fuel cell is stopped.SOLUTION: There are included residual moisture content prediction means which, if a fuel cell stops during its startup process, predicts a residual moisture content remaining on an oxidizer electrode side in the fuel cell, and fuel cell startup means which, before starting the fuel cell, reduces the pressure of oxidant gas supplied to the fuel cell by a pressure adjustment valve below a prescribed operation pressure so that the predicted residual moisture content predicated by the residual moisture content prediction means will not exceed a prescribed moisture content.

Description

  The present invention relates to a fuel cell system, and more particularly to control at the time of startup of the fuel cell system.

  In a fuel cell, for example, hydrogen containing hydrogen and air containing oxygen as an oxidant are used to generate power by an electrochemical reaction and to produce water on the oxidant electrode side. The reaction product water is discharged to the outside of the fuel cell together with air as an oxidant, but a part of the generated water is recirculated to the fuel cell inlet by a humidifier in order to keep the electrolyte membrane in a humid atmosphere. Many systems are used. This is to prevent the electrolyte membrane from drying and the internal resistance from increasing and the output voltage of the fuel cell from decreasing.

  The humidification of the air by this humidifier is performed by humidifying to a nearly saturated humidity state in order to keep the electrolyte membrane in a humidity atmosphere, so that depending on the operating state, it may cause flooding that clogs water droplets or low temperature state There is a problem that the flow path is blocked by freezing (see, for example, Patent Documents 1 and 2).

  To solve such a problem of flooding and freezing of the air flow path of the fuel cell, as shown in Patent Document 1, when the fuel cell is stopped, air is sent into the fuel cell by the air compressor and remains. A scavenging treatment method has been proposed in which the moisture that is being discharged is discharged. Patent Document 2 discloses a method for preventing the air flow path from being blocked by reducing and correcting the amount of humidification in the humidifier when the fuel cell is operated at a low temperature.

  On the other hand, the fuel cell is activated in accordance with a driver's command, and the temperature rises toward the normal operation temperature due to the activation, and the allowable output increases. However, if a stop command is issued by the driver before the fuel cell reaches a predetermined operating temperature, the fuel cell stops in the middle of the startup process. In this case, if the supply of the reaction gas to the fuel cell is immediately stopped to stop the power generation, the fuel cell is stopped without reaching the predetermined temperature. Because of the nature of fuel cells, water is generated during power generation.If power generation is stopped while the temperature of the fuel cell is low, the water generated by power generation from the start to the start is In other words, there is a problem that the gas flow path is blocked (see, for example, Patent Document 3).

  In Patent Document 3, in such a start-up from a low temperature, even when a driver in the middle of the start issues a stop command for the fuel cell, the fuel cell is not immediately stopped and power generation is continued to generate heat. An activation method has been proposed in which the temperature of the water is controlled to be equal to or higher than a predetermined value so that the generated water is discharged out of the electrode. However, this method has a problem that the driver may give a sense of incongruity because the fuel cell does not stop but continues to generate power even though the driver has issued a command to stop the fuel cell.

JP 2006-190616 A JP 2003-197237 A JP 2004-152599 A

  As in the prior art described in Patent Document 2, when the fuel cell is operated, the humidification amount in the humidifier is continuously reduced and corrected to prevent the air flow path from being blocked. There has been a problem that the humidification amount becomes too small to maintain the humidity atmosphere of the electrolyte membrane, the internal resistance increases, and the performance output of the fuel cell decreases.

  By the way, when the fuel cell is stopped, as shown in Patent Document 1, a scavenging process is performed in which air is sent into the fuel cell by an air compressor and moisture remaining in the air side electrode is discharged. It is common. The scavenging process in the stopping process is also performed when the fuel cell is stopped in the middle of the starting process, and water remaining in the fuel cell is discharged.

  On the other hand, the amount of water inside the air side electrode of the fuel cell increases with an increase in the amount of generated water due to an increase in the amount of power generation after the start of startup, and the temperature of the fuel cell gradually rises upon startup. Initially, when the temperature of the fuel cell is low, the moisture in the air side electrode of the fuel cell exists in the flow path in the form of water droplets, and shifts to the water vapor state as the temperature of the fuel cell rises. When the normal operating temperature is reached, the water contained in the flow path is almost water vapor. For this reason, when the temperature of the fuel cell is stopped at the normal operating temperature, water as water vapor can be easily discharged together with air by the scavenging process. However, when the temperature of the fuel cell is equal to or lower than the normal operating temperature as during startup, a large amount of water is in the form of water droplets. For this reason, in the scavenging process by stopping during startup when the temperature of the fuel cell is lower than the normal operating temperature, the amount of water that can be discharged even if air is sent to the air side electrode is when the fuel cell has reached the normal operating state Will be less than. As a result, if the fuel cell is stopped during the start-up process of the fuel cell, the water remaining in the air side electrode of the fuel cell cannot be sufficiently discharged even by the scavenging process, and the residual water does not remain after the fuel cell is stopped. There has been a problem that there exists a specific time zone that would block the air flow path. In addition, when starting from a low temperature, there is a problem in that the residual water freezes in the air flow path and closes the air flow path.

  In view of this, the present invention provides a fuel when the fuel cell is stopped in a specific time zone in which, when the fuel cell is stopped in the starting process of the fuel cell, residual water closes the air flow path after the fuel cell is stopped. The object is to reduce the amount of residual moisture in the battery.

  A fuel cell system according to the present invention includes a fuel cell that generates electric power by an electrochemical reaction between a fuel gas and an oxidant gas, a pressure control valve that adjusts the pressure of the oxidant gas in the fuel cell to a predetermined operating pressure, A fuel cell system including a control unit that controls the pressure of the oxidant gas by the pressure control valve, wherein the fuel cell activation means is configured to stop the fuel cell during the activation process in the fuel cell activation process. A residual moisture amount predicting means for predicting a residual moisture amount remaining on the oxidant electrode side in the fuel cell, and a predicted residual moisture amount predicted by the residual moisture amount predicting means so as not to exceed a predetermined moisture amount. Fuel cell starting means for starting the fuel cell by lowering the pressure of the oxidant gas supplied to the fuel cell by the pressure control valve below a predetermined operating pressure; Means for calculating the amount of water present in the oxidant gas in the fuel cell based on the amount of water in the oxidant gas after the reaction of the fuel cell; A discharge water amount prediction means for predicting the amount of water discharged from the oxidant electrode side in the fuel cell when the fuel cell is stopped during the starting process based on the physical amount of the agent gas, and the existing water content A residual water amount remaining on the oxidizer electrode side in the fuel cell after the fuel cell is stopped is predicted from a difference between the existing water amount calculated by the amount calculating unit and the predicted discharged water amount predicted by the discharged water amount predicting unit. It is characterized by doing. The fuel cell starting means may control the pressure of the oxidant gas supplied to the fuel cell by the pressure control valve when the temperature of the fuel cell is in a predetermined temperature range during the low temperature starting process of the fuel cell. It is also preferable to start the fuel cell by lowering it below a predetermined operating pressure.

  In the fuel cell system according to the present invention, the physical amount of the oxidant gas after the reaction is preferably the water amount, pressure, temperature, and flow rate of the oxidant gas after the reaction.

  The present invention relates to an interior of a fuel cell when the fuel cell is stopped in a specific time zone in which, when the fuel cell is stopped in the starting process of the fuel cell, residual water closes the air flow path after the fuel cell is stopped. The residual moisture content can be reduced.

It is a control system diagram showing an embodiment of a fuel cell system according to the present invention. In embodiment of the fuel cell system which concerns on this invention, it is a characteristic map for calculating an estimated discharge | release water amount. In the reference example of the fuel cell system which concerns on this invention, it is a flowchart which shows the starting means to start by flowing air into a humidifier bypass pipe line in a specific time slot | zone. In the reference example of the fuel cell system according to the present invention, the change in the temperature of the fuel cell and the amount of water in the air side electrode of the fuel cell when starting by flowing air through the humidifier bypass pipe in a specific time zone is shown. It is a graph. In the reference example of the fuel cell system which concerns on this invention, it is a flowchart which shows the starting means which judges a specific time slot | zone based on the temperature of a fuel cell, and starts by flowing air through a humidifier bypass line. In the reference example of the fuel cell system concerning the present invention, it is a flow chart which shows starting means which makes the flow of an air compressor increase from the optimal gas flow to generated electric power in a specific time slot. In the reference example of the fuel cell system according to the present invention, the temperature of the fuel cell and the air side electrode of the fuel cell when starting the air compressor by increasing the flow rate of the air compressor from the optimum gas flow rate for the generated power in a specific time zone. It is a graph which shows the change of moisture content. In the reference example of the fuel cell system according to the present invention, a flowchart showing the starting means for determining the specific time zone based on the temperature of the fuel cell and starting the air compressor by increasing the flow rate of the air compressor from the optimum gas flow rate for the generated power. It is. 5 is a flowchart showing an activation means that is activated by reducing the air pressure by an air pressure control valve in a specific time zone in the embodiment of the fuel cell system according to the present invention. In the embodiment of the fuel cell system according to the present invention, it is a flowchart showing an activation means for determining a specific time zone based on the temperature of the fuel cell, and starting by depressurizing the air pressure with an air pressure control valve.

  A preferred embodiment of the present invention will be described with reference to FIG. FIG. 1 is a control system diagram showing an embodiment according to the fuel cell system 10 of the present invention. As shown in FIG. 1, the fuel cell system 10 of the present embodiment uses air containing oxygen as the oxidant gas and hydrogen as the fuel gas. Air, which is an oxidant gas, is sucked into the air compressor 14 from the air through the air suction line 19 via the intake flow meter 18 and the air filter, and the discharge air pressurized by the air compressor 14 is discharged from the compressor. 20 to the humidifier 31. The humidifier 31 contains, for example, a large number of hollow fiber membranes. When fluids having different water contents are supplied to the inside and the outside of the hollow fiber membranes, the water in the fluid having a high water content permeates the hollow fiber membranes. Thus, a hollow fiber humidifier utilizing the property of moving to a fluid having a low water content is used. The air that has entered the humidifier 31 is humidified by moisture generated by the reaction in the fuel cell 11 in the humidifier 31, becomes humid air, and is supplied to the fuel cell 11 from the air supply line 23. In the air that has entered the fuel cell from the air side electrode 12, which is the oxidant electrode of the fuel cell 11, oxygen is reduced by a power generation reaction with hydrogen supplied from the hydrogen system. Then, the product water as a result of the reaction increases in the air as water vapor or water droplets. The air whose water content has increased after the reaction is discharged to the air discharge pipe 24 of the fuel cell 11. The air discharge pipe 24 is provided with an air pressure adjusting valve 28 for controlling the air pressure in the air side electrode 12 to a predetermined operating pressure. In addition, an air discharge conduit 24 between the air pressure control valve 28 and the air side electrode 12 has a water content for measuring the water content, temperature, and pressure of the air after reaction discharged from the air side electrode 12. A sensor 25, a temperature sensor 26, and a pressure sensor 27 are attached. The reacted air containing a large amount of moisture exhausted from the air side electrode 12 of the fuel cell 11 is removed by the humidifier 31 in order to use a part of the moisture as additional moisture to the supply air. The exhaust air whose moisture content has decreased flows downstream through the exhaust pipe 29. A silencer 53 is provided in the middle of the exhaust line 29, and the exhausted air after the reaction that has passed through the silencer 53 is exhausted from the atmosphere discharge port 57 to the atmosphere.

  On the other hand, depending on the operating state of the fuel cell 11, it may be necessary to reduce the amount of humidification to the supply air by the humidifier 31. For this purpose, the compressor discharge pipe 20 at the outlet of the air compressor 14 and the air supply pipe 23 are connected by bypassing the humidifier 31, and the compressor discharge air is supplied to the air supply pipe 23 without being humidified. A humidifier bypass pipe 33 that reduces the amount of moisture in the air supplied to the air side electrode 12 of the fuel cell 11 is provided. The humidifier bypass pipe 33 is provided with a humidifier bypass valve 35 that opens and closes the humidifier bypass pipe 33. The humidifier bypass valve 35 may perform only an opening / closing operation between fully open and fully closed, or may be a valve that can maintain an opening degree in the middle of fully open and fully closed. Good. Further, the valve drive unit may be a pneumatic drive unit using a diaphragm or the like, or may be an electric drive unit.

  In addition, the air supply line 23 and the air discharge line 24 to the fuel cell 11 enter the fuel cell 11 when the fuel cell 11 is stopped, and hydrogen remaining in the fuel cell 11 A shut-off valve that is closed when stopped may be provided so as to react and prevent deterioration of the catalyst or the like. When such a shut-off valve is provided, the shut-off valve of the air supply pipe 23 is provided between the confluence of the humidifier bypass pipe 33 and the air supply pipe 23 and the humidifier 31, and the air supply pipe The humidifier bypass valve 35 may be opened while the shutoff valve of the passage 23 is closed so that the entire amount of compressor discharge air from the air compressor 14 is bypassed.

  If the moisture sensor 25 can continuously measure the moisture content, the moisture sensor 25 can measure the moisture content by measuring the impedance or the capacitance of the measurement unit made of a hygroscopic polymer material or the like. Alternatively, the voltage or current value of the electrochemical cell arranged between the measurement gas and the reference gas may be measured, and the moisture content may be measured from the result. Further, the temperature sensor may be a thermocouple type temperature sensor or other type such as a bimetal type. Furthermore, the pressure sensor may be a pressure sensor using a pressure element or the like as long as the pressure can be detected continuously, or a pressure detector including a diaphragm type pressure receiving portion.

  The air pressure control valve 28 may be a clove type control valve or an angle type control valve as long as it can continuously adjust the air pressure after reaction in the air discharge pipe 24 of the fuel cell 11. A cage type control valve may be used. Moreover, the drive part of a control valve may be an air drive type, and may be electrically driven.

  In the fuel cell system 10 of the present embodiment, the air compressor 14 is a scroll type. The scroll type air compressor 14 is a kind of positive displacement type air compressor, and the air flow rate can be adjusted mainly by adjusting the rotation speed. In addition, since there is no bleed or the like for preventing surging in the positive displacement type, in this embodiment, the intake flow rate measured by the intake flow meter 18 is substantially the same as the discharge flow rate. The scroll type air compressor 14 has a characteristic that the discharge pressure is high when the discharge air flow rate is small, and the discharge pressure decreases as the discharge air flow rate increases. During normal operation of the fuel cell system 10, the air flow rate is adjusted by adjusting the rotation speed of the air compressor 14 and the rotation speed of the motor 16, and the air pressure is adjusted at the outlet of the air side electrode 12 of the fuel cell 11. It is adjusted by the valve 28. As long as the air compressor 14 can supply air of the required pressure and flow rate to the air side electrode 12 of the fuel cell 11, it is not limited to the scroll type and may be a screw type or a centrifugal type blower.

  Hydrogen gas as fuel gas is stored in a hydrogen gas tank 41. Hydrogen is supplied from a hydrogen gas tank 41 to a hydrogen side electrode 13 which is a fuel side electrode of the fuel cell 11 through a hydrogen supply line 43. A part of the hydrogen supplied to the fuel cell 11 is consumed by reacting with oxygen in the air, which is an oxidant supplied to the air side electrode 12, but the hydrogen not consumed is discharged from the hydrogen side electrode 13. After being discharged from the pipe 44, it is recirculated to the hydrogen supply pipe 43 by a hydrogen circulation pump 46 provided in a hydrogen circulation pipe 45 connecting the hydrogen discharge pipe 44 and the hydrogen supply pipe 43. The hydrogen content consumed by the power generation is replenished from the hydrogen gas tank 41 through the hydrogen supply line 43. The amount of hydrogen gas to be replenished is adjusted by the hydrogen supply control valve 42. Since the hydrogen system is a circulation system, impurities such as nitrogen and moisture that cross leak from the air side electrode 12 are concentrated when the system is operated for a long time. Therefore, when such impurities have been concentrated to some extent, the discharge valve 49 of the hydrogen-based atmospheric discharge pipe 48 connected to the hydrogen discharge pipe 44 is opened to supply a predetermined amount of hydrogen gas to the hydrogen-based atmospheric discharge pipe. The air is discharged from the road 48 to the outside air. In this case, the exhaust gas is mixed with the exhaust air by the mixer 55 connected to the exhaust hydrogen dilution pipeline 51 so that the high concentration hydrogen gas is not directly released to the atmosphere, and the concentration is lowered to the atmosphere. It comes to discharge.

  The meters 18, 25, 26, 27, the control valves 28, 35, 42, 49, the fuel cell 11, the air compressor 14, and the motors 16, 47 of each pump are all connected to the control unit 61. The measured values from the respective meters 18, 25, 26, 27 are input to the control unit 61. The control unit 61 instructs the opening of each control valve 28, 35, 42, 49, and the rotational speed command of the motors 16, 47. To control the entire fuel cell system 10. The control unit 61 includes a CPU and a storage unit, and may be configured to perform overall control by software, or may be configured to perform control by combining electric circuits. The controller 61 may be input with data from the vehicle such as the running state of the vehicle and the addition of necessary requirements. A storage unit 63 that holds control data such as a control map necessary for the control operation is connected to the control unit 61 via a data bus 65.

  In the present embodiment, the control unit 61 includes a discharge water amount prediction unit that predicts the amount of water discharged from the air side electrode 12 of the fuel cell 11 when the fuel cell 11 stops during the starting process. When the fuel cell 11 is stopped during the starting process of the fuel cell 11, the amount of water that can be discharged from the air side electrode 12 of the fuel cell 11 is the amount of water, pressure, temperature, and air compression of the air at the air side electrode outlet. Since the amount of compressed air discharged from the compressor 14 varies in various ways, the predicted calculation of the amount of discharged water includes the air pressure and temperature at the air side pole outlet stored in the storage unit 63 and the discharge of the air compressor 14. Use a map of wastewater flow rate. FIG. 2 shows a characteristic map for calculating the amount of discharged water. In this embodiment, since the scroll type air compressor is used, the intake air flow rate and the discharge air flow rate of the air compressor 14 are substantially the same, and therefore the output of the intake flow meter 18 is output as the discharge air flow rate. Is used. Further, the discharge air flow rate of the air compressor 14 and the flow rate of the fuel cell 11 are changed as in the case of performing an operation in which a part of the discharge air of the air compressor 14 is discharged from the atmospheric discharge port 57 by bypassing the fuel cell 11. When there is a large difference in the air flow rate at the outlet of the air side electrode 12, the discharge air flow rate of the air compressor 14 and the outlet air flow rate of the air side electrode 12 are greatly different. It is preferable to use a flow meter attached to the air flow rate obtained by subtracting the bypass flow rate from the discharge air flow rate of the air compressor 14 instead of the air flow rate or the output of the air discharge line 24 of the air side electrode 12.

  FIG. 2A is a diagram showing one of a plurality of maps showing the relationship between the discharge air flow rate Q of the air compressor 14 when the fuel cell 11 is stopped and the drainage amount W in the scavenging process after the fuel cell is stopped. It is. Three lines in the figure show the relationship between the discharge air flow rate and the amount of drainage when the scavenging time D of the scavenging process performed after the fuel cell 11 is stopped is 100 seconds, 200 seconds, and 300 seconds. In FIG. 2A, the pressure P, temperature T, and moisture content X at the air side pole outlet are constant.

  For example, if it is determined that the moisture in the air discharged from the outlet of the air-side electrode 12 is all water vapor from the state of the pressure P, temperature T and moisture amount X at the outlet of the air-side electrode 12, stop. The amount of drainage discharged later can be obtained by multiplying the discharge air flow rate Q of the air compressor 14 by the scavenging time D and the amount of moisture X contained in the unit volume. At this time, the map is a straight line proportional to the discharge air flow rate of the air compressor 14. Further, as the scavenging time D increases, the amount of drainage W drained by scavenging increases, but as the time increases, the ratio of the amount of drainage W per unit scavenging time decreases. On the other hand, from the state of the pressure P, the temperature T and the amount of water X at the outlet of the air side electrode 12, a considerable portion is in the state of water vapor, but when some water is present as water droplets, The amount of waste water W discharged after the stop cannot be obtained by simply multiplying the discharge air flow rate Q of the air compressor 14 by the scavenging time D and the amount of moisture X contained in the unit volume. That is, the water present as water vapor is substantially discharged by the discharge air from the air compressor 14, but the water present as water droplets is discharged unless the discharge air flow rate Q from the air compressor 14 increases to some extent. It does n’t come. Therefore, in such a state, the map is a curve with respect to the discharge air flow rate Q of the air compressor 14. Thus, the amount of water discharged after the fuel cell 11 is stopped varies in a complex manner depending on the pressure P, temperature T, and water amount X at the outlet of the air side electrode 12. Therefore, as shown in FIG. 2A, the discharge pressure P of the air compressor 14 in each state and the amount of water that can be discharged after stopping are stored in the storage unit 63 as map data, and can be detected without complicated calculations. The amount of waste water W discharged from the physical quantity can be easily predicted.

  FIG. 2B shows one of a plurality of maps indicating the relationship between the outlet pressure of the air side electrode 12 when the fuel cell 11 is stopped and the amount of drainage W drained by the scavenging process after the fuel cell 11 is stopped. It is shown. The three lines in the figure are the outlets of the air electrode 12 when the scavenging time D of the scavenging process performed after the stop of the fuel cell 11 is 100 seconds, 200 seconds, and 300 seconds, as in FIG. The relationship between the pressure P and the amount of drainage W is shown. In FIG.2 (b), the discharge air flow rate Q of the air compressor 14, the temperature T of the air side pole exit, and the moisture content X are constant.

  As the pressure P at the outlet of the air-side electrode 12 becomes lower, the water in the air-side electrode 12 becomes a water vapor state, so that the amount of waste water W drained by the scavenging process after the fuel cell 11 is stopped increases. On the contrary, when the pressure P increases, the ratio of water vapor in the air side electrode 12 decreases, and conversely, the ratio of water droplets increases, so that the air compressor 14 during the scavenging process is increased. When the discharge air flow rate Q is the same, the amount of waste water W drained in the scavenging process after the fuel cell 11 is stopped decreases. Further, as the scavenging time D increases, the amount of drainage W drained by scavenging increases, but as the time increases, the ratio of the amount of drainage W per unit scavenging time decreases.

  FIG. 2 (c) shows one of a plurality of maps showing the relationship between the outlet temperature of the air-side electrode 12 when the fuel cell 11 is stopped and the amount of waste water W drained by the scavenging process after the fuel cell 11 is stopped. It is shown. The three lines in the figure are the air side poles in the cases where the scavenging time D of the scavenging process performed after the stop of the fuel cell 11 is 100 seconds, 200 seconds, and 300 seconds, as in FIGS. 2 (a) and 2 (b). The relationship between the temperature T of 12 air side pole exits and the amount of waste_water | drain W is shown. In FIG.2 (c), the discharge air flow rate Q of the air compressor 14, the pressure P of the air side pole exit, and the moisture content X are constant.

  As the temperature T at the outlet of the air side electrode 12 becomes higher, the moisture in the air side electrode 12 becomes a water vapor state, so that the amount of waste water W drained by the scavenging process after the fuel cell 11 is stopped increases. On the contrary, when the temperature T is lowered, the ratio of water vapor in the air side electrode 12 is decreased and the ratio of water droplets is increased, so that the air compressor 14 in the scavenging process is increased. When the discharge air flow rate Q is the same, the amount of waste water W drained in the scavenging process after the fuel cell 11 is stopped decreases. Further, as the scavenging time D increases, the amount of drainage W drained by scavenging increases, but as the time increases, the ratio of the amount of drainage W per unit scavenging time decreases as shown in FIG. This is the same as FIG.

  In the present embodiment, the above map is stored in the storage unit 63, and the control unit 61 predicts the amount of waste water W discharged from the air side electrode 12 in the fuel cell when the fuel cell stops during the starting process.

  In addition to the map for calculating the predicted discharged water amount, the storage unit 63 described above, as well as the optimal flow rate of air, hydrogen gas, the steady operation pressure, and the permissible flow rate in the normal operation. Stores data, maps, etc. that can be used to calculate the relationship between output rise and temperature, normal start-up process, and predicted exhausted water content and existing water content in each state during normal start-up process. The unit 61 can calculate the existing water amount, the predicted discharged water amount, the predicted residual water amount, and the like in the normal startup state.

First, the startup of the fuel cell system 10 according to a reference example of the present invention will be described with reference to FIGS. 3 and 4. FIG. 3 is a flowchart showing the starting means of this reference example, FIG. 4 (a) is a graph showing the change in temperature of the fuel cell 11 with respect to the time of the starting process, and FIG. 4 (b) is the existing existence of the air side electrode 12. It is a graph which shows the change of a moisture content and a prediction residual moisture content. 4B shows a change in the existing water content in the air side electrode 12 of the fuel cell 11, and the trapezoidal curve shows the residual water content remaining after the scavenging process after the fuel cell 11 is stopped. Is shown. The solid lines connecting a ₁ , b ₁ , c ₁ , d ₁ , e ₁ and a ₁ , p ₁ , q ₁ , r ₁ , s ₁ , u ₁ in the figure are those in the case of normal startup according to the prior art. shows the change of the _{amount, b 1, b 1 ',} c 1', d 1 ', e 1', e 1 and _{p 1, p 1 ', q} 1', r 1 ', s 1', s 1 The dotted line connecting the lines indicates the change of each quantity at the time of start-up according to this reference example, and one point connecting b ₁ , c ₁ ″, d ₁ ″, e ₁ and p ₁ , q ₁ ″, r ₁ ″, s _1. A chain line indicates a change in each amount in another activation state of this reference example.

As shown in step S101 of FIG. 3, the control unit 61 starts the fuel cell 11 in the normal starting process. As shown in FIG. 4A, when the fuel cell 11 is started in a state where the temperature at the start is h ₁ , the fuel cell 11 reduces the power generation efficiency for a certain period of time, and the temperature of the fuel cell 11 Perform warm-up operation that raises. Temperature of the fuel cell 11 by the warm-up operation is increased to i _1. Thereafter, the fuel cell 11 increases the allowable load while controlling so that the ratio of the air amount to the power generation amount and the oxygen amount to the power generation amount becomes an optimum ratio. Moreover, in order to maintain the humidity atmosphere of the electrolyte membrane, the air discharged from the air compressor 14 is humidified by a humidifier.

As shown from a ₁ to b ₁ in FIG. 4B, when the fuel cell 11 is started, the generated water generated by the increase in the amount of power generation also increases, and the outlet of the air side electrode 12 of the fuel cell 11 increases. The amount of water will also increase. 4 (a) and 4 (b), the discharge flow rate of the air compressor 14 is controlled by controlling the rotation speed of the air compressor 14 so that the ratio of the oxygen amount to the power generation amount becomes an optimum ratio. . Further, the outlet pressure of the air side electrode 12 is maintained at a predetermined operating pressure by the air pressure control valve 28. On the other hand, when the fuel cell 11 is activated, it is predicted that the fuel cell 11 remains in the air side electrode 12 when the fuel cell 11 is stopped during the activation process, as indicated by a ₁ to p ₁ in FIG. The predicted residual moisture content will gradually increase.

  In this starting process, as shown in step S102 of FIG. 3, the control unit 61 acquires the signal of the moisture amount sensor 25 of the air side electrode 12 of the fuel cell 11, and based on this, the control unit 61 proceeds to step S103 of FIG. As shown, the amount of water present in the air side electrode 12 of the fuel cell 11 is calculated. For example, the inside of the air side electrode 12 of the fuel cell 11 is based on the amount of water obtained by subtracting 1/2 of the generated water amount calculated from the electrical output of the fuel cell 11 from the amount of water at the outlet of the air side electrode 12 of the fuel cell 11. The average moisture content per unit volume is calculated, and the volume of the air flow path is multiplied by this to calculate the existing moisture content existing in the air side electrode 12 of the fuel cell 11. The calculation of the existing moisture amount is not limited to the above method, and the moisture amount per unit volume at the outlet of the air side electrode 12 is calculated from the moisture amount at the outlet of the air side electrode 12, and this is calculated. The maximum water content multiplied by the volume may be used as the existing water content. Further, during startup of the fuel cell 11, the control unit 61 discharges air from the air compressor 14 based on intake air flow data measured by the intake air flow meter 18 of the air compressor 14, as shown in step S <b> 104 in FIG. 3. Based on the flow rate, the signals of the measuring devices of the moisture sensor 25, the temperature sensor 26, and the pressure sensor 27 at the outlet of the air side electrode 12, and the discharged moisture calculation map stored in the storage unit 63 described in FIG. Thus, the predicted discharged water amount that can be drained by the scavenging process when the fuel cell 11 is stopped is calculated. Then, as shown in step 105 of FIG. 3, the control unit 61 subtracts the predicted discharged water amount from the existing water amount, and when the fuel cell 11 stops at that time, the air side electrode 12 of the fuel cell 11. Calculate the predicted amount of residual moisture that is expected to remain inside.

As described above, the control unit 61 always calculates the predicted residual moisture amount in the startup process of the fuel cell 11. Then, the control unit 61, as shown in step S106 of FIG. 3, continue the start-up of the fuel cell 11 while comparing the results and limits the amount of residual water W _0. Control unit 61, as shown in step S106 of FIG. 3, when the prediction residual moisture content of the exceeds the limit amount of residual water W _0, the fuel cell air side of the fuel cell 11 when stopped in the middle of the activation process It is determined that the inside of the pole 12 has entered a specific time zone in which the moisture content exceeding the limit residual moisture content W ₀ is included. This is when the _{t 1} shown in Figure 4 (b).

Then, the control part 61 outputs the signal which opens the humidifier bypass valve 35, and opens the humidifier bypass valve 35, as shown to step S107 of FIG. When the humidifier bypass valve 35 is opened, air that does not humidify the discharge air of the air compressor 14 flows into the air supply line 23 through the humidifier bypass line 33. As a result, the amount of moisture in the air supplied to the air side electrode 12 of the fuel cell 11 is reduced. Then, as shown by the dotted arrows from b ₁ to b ₁ ′ in FIG. 4B, the moisture content of the air supplied to the air side electrode 12 decreases by y ₁ . On the other hand, discharge air flow rate and the air-side electrode 12 outlet pressure of the air compressor 14, since no temperature changes, as the p ₁ shown in FIG. 4 (b) shown by the dotted arrow in the p _{1 ',} the fuel cell prediction residual moisture amount when 11 is stopped midway start may decrease by y _1, the prediction residual moisture amount is less than the limit amount of residual water W _0. If the start-up is continued with the humidifier bypass valve 35 open, the existing water content in the air-side electrode 12 is changed from b ₁ ′ to c ₁ ′, d as indicated by the dotted arrow in FIG. It changes with ₁ '. On the other hand, the predicted residual moisture content also changes from p ₁ ′ to q ₁ ′, r ₁ ′ as indicated by the dotted arrows in FIG. In this state, the predicted residual water content at the points q ₁ ′ and r ₁ ′ is not more than the limit residual water content W ₀ . If the predicted residual moisture amount at the points q ₁ ′ and r ₁ ′ is equal to or greater than the limit residual moisture amount W ₀ , the humidifier bypass pipe 33 and the humidifier bypass valve 35 are connected to the fuel cell system 10. Make it large to fit.

As shown in FIG. 4A, the temperature of the fuel cell 11 rises to k ₁ ′ at time t ₃ . Then, the ratio of water vapor in the water inside the air side electrode 12 of the fuel cell 11 starts to rise rapidly. As a result, when the fuel cell 11 stops in the middle of startup, the predicted discharged water amount due to the scavenging after the stop increases rapidly. On the other hand, since the humidifier bypass valve 35 remains open, the existing water content of the air side electrode 12 is between d ₁ ′ and e ₁ ′ as shown by the dotted arrow in FIG. It remains lower than the normal startup state. For this reason, as shown from r ₁ ′ to s ₁ ′ in FIG. 4 (b), the predicted residual water content rapidly decreases from the vicinity of the limit residual water content W ₀ .

Then, at time t ₄ in FIG. 4B, the temperature of the fuel cell 11 rises to k _{1 in} FIG. 4A, and the ratio of water vapor to the moisture content of air in the air side electrode 12 further increases. Even under normal startup conditions, when the fuel cell 11 stops in the middle of startup, the remaining moisture amount can be reduced to a limit residual moisture amount W ₀ or less by scavenging after stopping. Control unit 61 is activated constantly, while calculating the difference between the predicted amount of residual water and limit the amount of residual water W ₀ in the case of a normal startup state. Then, as shown in step S108 of FIG. 3, if the predicted residual water content in the case of a normal startup state is smaller than the limit amount of residual water W _0, the fuel cell is a fuel cell in the middle of the activation process 11 Is stopped, it is determined that the fuel cell 11 has escaped from the specific time zone in which the moisture content exceeding the limit residual moisture content W ₀ is contained inside the air side electrode 12.

Then, as shown in step S109 in FIG. 3, the control unit 61 outputs a signal for closing the humidifier bypass valve 35, closes the humidifier bypass valve 35, and as shown in step S110 in FIG. Then, the discharge air of the air compressor 14 is passed through the humidifier 31 to return to the normal startup control in which moisture is humidified in the air supplied to the fuel cell 11. Then the existing water content of the air-side electrode 12 of the fuel cell 11 is returned to e ₁ of the normal operation state from e _{1 'as} shown by dotted arrows in Figure 4 (b). At the same time, it returns the predicted residual water content from be s _{1 'to} s ₁ of the normal operation. Then, further progressed startup of the fuel cell 11 reaches the normal operating temperature l _1, moisture of the air-side electrode 12 is substantially entirely in a state of water vapor, existing also the fuel cell 11 is stopped by the scavenging process after the stop Since all the moisture content can be discharged, the predicted residual moisture content becomes zero in the normal operation state.

Thus, according to the present reference example, when the fuel cell is stopped in the starting process of the fuel cell 11, the fuel cell is in a specific time zone in which residual water closes the air flow path after the fuel cell is stopped. There is an effect that the amount of residual water in the fuel cell when the operation is stopped can be reduced. Even when the fuel cell 11 is stopped by a driver's command or the like in the middle of starting, the amount of water remaining in the air side electrode 12 of the fuel cell 11 by the scavenging process after the stop is the limit residual water amount W _0. Thus, there is an effect that the air side electrode 12 is less likely to be blocked by the residual moisture due to the stop during the activation. Further, since the residual water content is reduced, there is an effect that the amount of freezing can be reduced even when the residual water is frozen.

In the description of the above reference example, the humidifier bypass valve 35 is opened in a specific time period so that the expected residual moisture amount is set to be equal to or less than the limit residual moisture amount W ₀ . The opening and closing of the humidifier bypass valve 35 is operated in the same manner as the control valve by duty ratio control, and as shown by a one-dot chain line connecting p ₁ , q ₁ ″, r ₁ ″, s ₁ in FIG. The predicted residual moisture amount may be controlled to be the limit residual moisture amount W ₀ , or a plurality of bypass flow rates may be realized by stopping at the intermediate opening. Thus the extent below the limit amount of residual water W _0, the prediction residual moisture content may be adjusted stepwise humidifier bypass valve 35 so as not to exceed the limit amount of residual water W _0.

  Further, as shown in FIG. 5, a temperature map of the fuel cell 11 in a specific time zone is stored in the storage unit 63 from the temperature and start characteristics of the fuel cell 11 when the fuel cell 11 is started, and the fuel cell 11 is stored. 11, a specific temperature range in which the fuel cell enters a specific time zone is obtained from the map of the storage unit 63 based on the temperature at the time of start-up, and humidification is performed when the temperature of the fuel cell 11 is within the specific temperature range. It is also preferable to start by opening the detector bypass valve 35.

  As shown in step S502 of FIG. 5, after the fuel cell 11 is started, the control unit 61 acquires the temperature of the fuel cell 11 at the time of start-up, and in the temperature and the storage unit 63, as shown in step S503 of FIG. Based on the stored map, a temperature range in which the fuel cell 11 enters a specific time zone during a normal startup process is acquired. Then, as shown in step S504 of FIG. 5, when the temperature of the fuel cell rises to a temperature determined to have entered a specific time zone, the control unit 61 outputs a signal for opening the humidifier bypass valve 35. Then, the humidifier bypass valve 35 is opened. Then, the controller 61 continues to monitor the temperature of the fuel cell 11, and when it is determined that the temperature has deviated from the temperature range of a specific time zone as shown in step S506 in FIG. A command to close the humidifier bypass valve 35 is output, and the humidifier bypass valve 35 is closed. And it returns to normal starting operation | movement as shown to step S507 of FIG.

  In the above description, the temperature of the fuel cell 11 in a specific time zone is controlled by calculating the range, but the outlet air temperature of the air side electrode 12 of the fuel cell 11 is calculated and controlled based on this. It's also good. Moreover, it is also preferable to predict the time which becomes a specific time slot | zone from the temperature conditions at the time of starting, and to open and close the humidifier bypass valve 35 based on the time.

Next, in the starting process of the fuel cell 11, the predicted residual moisture amount is controlled to be equal to or less than the limit residual moisture amount W ₀ by increasing the rotational speed of the air compressor 14 and increasing the air flow rate flowing into the air side electrode 12. The starting means to perform will be described with reference to FIGS. Components similar to those in FIG. 4 are denoted by the same reference numerals, and description thereof is omitted. FIG. 6 is a flowchart showing the operation of the present reference example, FIG. 7 (a) is a graph showing the change in the temperature of the fuel cell with respect to the time of the starting process, and FIG. 7 (b) is the existing water content of the air side electrode 12. It is a graph which shows the change of residual moisture content. The solid lines connecting a ₂ , b ₂ , c ₂ , d ₂ , e ₂ and a ₂ , p ₂ , q ₂ , r ₂ , s ₂ , u ₂ in FIG. 1, b ₂ , c ₂ ′, d ₂ ′, e ₂ and p ₂ , q ₂ ′, r ₂ ′, s ₂ , and a dash-dot line and p ₂ , q ₂ ″, A two-dot chain line connecting r ₂ ″ and s ₂ indicates a change in each amount in the activated state of this reference example.

As shown in steps S201 to S206 in FIG. 6, the control unit 61 can drain water by the existing moisture content in the air side electrode 12 of the fuel cell 11 and the scavenging process after stopping when stopping halfway in the starting process. When the predicted residual water content is calculated, the predicted residual water content is always calculated when the normal start-up process is stopped, and the predicted residual water content exceeds the limit residual water content W _0. 61, when the fuel cell 11 stops in the middle of the start-up process, and enters the specific time zone in which the water side electrode 12 of the fuel cell 11 contains a water content exceeding the limit residual water content W _0. to decide.

  Then, as shown in step S207 of FIG. 6, the control unit 61 starts air compressor discharge flow rate increase control that performs start-up control while increasing the discharge air flow rate of the air compressor 14. Specifically, the rotational speed of the motor 16 of the air compressor 14 is such that an air flow rate greater than the air flow rate at which the ratio of the air amount to the power generation amount of the fuel cell 11 and the oxygen amount to the power generation amount is an optimal ratio flows. Is output to the motor 16 to increase the rotational speed of the air compressor 14 and increase the discharge air flow rate of the air compressor 14.

When the discharge air flow rate of the air compressor 14 is increased, the moisture content by the humidifier 31 does not change, so the moisture content of the air in the air side electrode per unit volume decreases. Then, the existing moisture content of the air side electrode 12 of the fuel cell 11 is the existing moisture content in the normal operation state as shown by a one-dot chain line connecting b ₂ , c ₂ ′, d ₂ ′, and e ₂ in FIG. it becomes as small as y ₂ than. Furthermore, when the discharge air flow rate of the air compressor 14 increases, as shown in FIG. 2A, the amount of waste water scavenged within a predetermined scavenging time in the scavenging after the fuel cell 11 stops is increased. For this reason, the amount of residual water after scavenging is reduced by y ₃ shown in FIG. Decrease y ₂ of the existing water content, and the outlet moisture content of the air-side electrode 12 of the fuel cell 11, the amount of decrease in the discharge air flow rate of the air compressor 14 performs the computation of the existing water content, the storage unit 63 It can be calculated by comparing with the stored moisture content map at the time of normal startup. Further, the increase y ₃ in the scavenging water amount can be calculated by calculating the predicted discharged water amount from the map of the storage unit 63 and comparing it with the predicted discharged water amount in the normal operation. Then, the rotation of the motor 16 of the air compressor 14 is appropriately performed so that the total y ₁ of y ₂ and y ₃ becomes larger than the difference between the predicted residual moisture amount in the normal operation state and the limit residual moisture amount W _0. By applying feedback to the number, the number of revolutions of the air compressor 14 is controlled so that the predicted residual moisture amount is lower than the limit residual moisture amount W ₀ , and the fuel cell is started.

Then, as shown in step S208 of FIG. 6, if the predicted residual water content in the case of a normal start process if it becomes smaller than the limit amount of residual water W _0, the fuel cell has been stopped in the middle of the activation process Then, it is determined that the fuel cell 11 has escaped from a specific time zone in which the moisture content exceeding the limit residual moisture content W ₀ is included in the air side electrode 12, and as shown in step S 209 of FIG. The machine discharge flow rate increase control is stopped, and as shown in step S210 of FIG. 6, the normal start-up operation is restored and the start-up of the fuel cell 11 is continued.

  Thus, according to the present reference example, when the fuel cell is stopped in the starting process of the fuel cell 11, the fuel cell is in a specific time zone in which residual water closes the air flow path after the fuel cell is stopped. There is an effect that the amount of residual water in the fuel cell when the operation is stopped can be reduced.

In the above description of the present embodiment, by increasing the rotational speed of the motor 16 of the air compressor 14 at certain times, as shown in FIG. 6, the expected amount of residual water is a limit amount of residual water W ₀ or less As described above, the temperature map of the fuel cell 11 in a specific time zone is stored in the storage unit 63 from the temperature of the fuel cell when the fuel cell 11 is started and the starting characteristics, A specific temperature range in which the fuel cell enters a specific time zone is obtained from the map of the storage unit 63 based on the temperature at the time of starting the battery 11, and the temperature of the fuel cell 11 is within this specific temperature range. It is also suitable as starting by raising the rotation speed of the motor 16 of the air compressor 14.

  In FIG. 8, steps S601 to S604 up to determining whether the fuel cell 11 has entered a specific time zone are the same as those in FIG. When the temperature of the fuel cell 11 reaches a temperature determined to have entered a specific time zone, the control unit 61 starts the air compressor discharge flow rate increase control as shown in step S605 of FIG. Then, as shown in step S606 of FIG. 8, when the temperature of the fuel cell 11 departs from the temperature range indicating a specific time zone, the air compressor discharge flow rate increase control is stopped, and step S608 of FIG. As shown in Fig. 2, the normal startup operation is restored.

  In the above description, the air compressor 14 is controlled by calculating the temperature range of the fuel cell 11 in a specific time zone. However, by calculating the outlet air temperature of the air side electrode 12 of the fuel cell 11, this is calculated. It is good also as controlling based on. Moreover, it is also preferable to predict the time which becomes a specific time slot | zone from the temperature conditions at the time of starting, and to start by starting and stopping the air compressor discharge flow rate increase control based on the time.

Next, referring to FIG. 9, in the starting process of the fuel cell 11 in the embodiment of the present invention, the air pressure at the air side electrode is decreased by the air pressure control valve 28, and the predicted residual moisture amount is set to the limit residual moisture amount W. _The starting means for controlling to ₀ or less will be described. FIG. 9 is a flowchart showing the starting means. In this case, the starting curve is the same as that in FIG. 4, and the change in the state quantity will be described with reference to FIG.

As shown in step S301 to step S306 in FIG. 9, the control unit 61 stopped in the middle of the normal moisture content and the existing water content in the air side electrode 12 of the fuel cell 11 as described above. In this case, the predicted amount of water that can be drained by the scavenging process after stoppage is calculated, and from this, the predicted residual water amount is always calculated when it is stopped during the start-up process. If it exceeds ₀ , the control unit 61 will contain a water content of the limit residual water content W ₀ or more in the air side electrode 12 of the fuel cell 11 when the fuel cell 11 stops in the middle of the starting process. Judge that it is in a specific time zone.

  Then, as shown in step S <b> 307 in FIG. 9, the control unit 61 starts the pressure reduction control in which the air pressure of the air side electrode 12 is reduced by the air pressure adjustment valve 28. Specifically, the control unit 61 increases the opening of the air pressure control valve 28 at the outlet of the air side electrode 12 of the fuel cell 11 to reduce the air pressure of the air side electrode 12 from the normal operating pressure. Is output. Thereby, the opening degree of the air pressure control valve 28 is increased, and the air pressure in the air side electrode 12 is lowered from the normal operation pressure. Then, as described with reference to FIG. 2B, the moisture inside the air-side electrode 12 shifts to a region where the proportion of water vapor increases due to a decrease in air pressure. This increases the amount of water that can be discharged by the scavenging process after stopping when the fuel cell 11 stops in the middle of starting.

The control unit 61 calculates the degree of pressure decrease and the increase rate of the predicted discharged water amount from the map stored in the storage unit 63. Then, the air pressure control valve 28 is started while controlling so that the increase rate of the predicted discharged water amount becomes the difference between the predicted residual water amount and the limit residual water amount W ₀ in normal startup.

That is, the air pressure control valve is configured so that the predicted discharged water amount is increased by the pressure reduction by the air pressure control valve 28 by the difference between the predicted remaining water amount and the limit residual water amount W _{0 in} the normal activation shown in FIG. To control. Then, the predicted residual water content in the air-side electrode of the fuel cell 11 is the limit residual as shown by p ₁ , q ₁ ″, r ₁ ″, s ₁ indicated by the dashed-dotted arrows in FIG. The water content changes along the line of the water content W ₀ , and the existing water content changes as b ₁ , c ₁ ″, d ₁ ″ e ₁ indicated by dotted arrows in FIG.

Then, as shown in step S308 of FIG. 9, if the predicted residual moisture amount when a normal start process if it becomes smaller than the limit amount of residual water W _0, the fuel cell has been stopped in the middle of the activation process It is determined that the fuel cell 11 has escaped from a specific time zone in which the moisture content exceeding the limit residual moisture content W ₀ is included in the air side electrode 12, and air compression is performed as shown in step S 309 in FIG. The decompression control by the machine 14 is stopped, and as shown in Step S310 of FIG. 9, the normal startup operation is restored and the startup of the fuel cell 11 is continued.

In the above description of the present embodiment, below the limit amount of residual water W ₀ is the expected amount of residual water to reduce the air pressure in the air-side electrode 12 in a specific time period by controlling the opening degree of the air pressure regulating valve 28 As shown in FIG. 10, from the temperature and starting characteristics of the fuel cell at the time of starting the fuel cell 11, the temperature of the fuel cell 11 is It is also preferable to start by lowering the air pressure of the air side electrode 12 by controlling the opening of the air pressure control valve 28 when the temperature is within the specific temperature range. This starting means shown in FIG. 10 is the same as the starting means described in FIG. 8 except that the pressure reduction control by the air pressure control valve is started or stopped in step S705 and step S707 in FIG. Similarly to the previous reference example, a time that is a specific time zone is predicted from the temperature condition at the time of startup, and when that time zone is reached, the opening degree of the air pressure control valve 28 is controlled to control the air side electrode 12. It is also preferable to start by lowering the air pressure.

  Thus, according to the present embodiment, when the fuel cell is stopped in the starting process of the fuel cell 11, the fuel cell is in a specific time zone in which residual water closes the air flow path after the fuel cell is stopped. There is an effect that the amount of residual water in the fuel cell when the operation is stopped can be reduced.

  DESCRIPTION OF SYMBOLS 10 Fuel cell system, 11 Fuel cell, 12 Air side pole, 13 Hydrogen side pole, 14 Air compressor, 16, 47 Motor, 18 Intake flowmeter, 19 Air suction line, 20 Compressor discharge line, 23 Air supply Pipe line, 24 Air discharge line, 25 Moisture sensor, 26 Temperature sensor, 27 Pressure sensor, 28 Air pressure control valve, 29 Exhaust line, 31 Humidifier, 33 Humidifier bypass line, 35 Humidifier bypass valve, 41 Hydrogen gas tank, 42 Hydrogen supply control valve, 43 Hydrogen supply line, 44 Hydrogen discharge line, 45 Hydrogen circulation line, 46 Hydrogen circulation pump, 48 Hydrogen-based atmospheric discharge line, 49 Discharge valve, 51 Discharge hydrogen dilution pipe Road, 53 Silencer, 55 Mixer, 57 Air outlet, 61 Control unit, 63 Storage unit, 65 Data bus.

Claims (3)

A fuel cell that generates electricity by an electrochemical reaction between a fuel gas and an oxidant gas;
A pressure control valve that adjusts the pressure of the oxidant gas in the fuel cell to a predetermined operating pressure;
A control unit for controlling the pressure of the oxidant gas by the pressure control valve;
A fuel cell system comprising:
A fuel cell starting means, in the fuel cell starting process, when the fuel cell is stopped during the starting process, a residual moisture amount predicting means for predicting a residual moisture amount remaining on the oxidant electrode side in the fuel cell; The pressure regulating valve reduces the pressure of the oxidant gas supplied to the fuel cell below a predetermined operating pressure so that the predicted residual moisture amount predicted by the residual moisture amount prediction means does not exceed a predetermined moisture amount. Fuel cell starting means for starting the fuel cell,
The residual moisture amount predicting means includes:
Means for calculating the amount of water existing in the oxidant gas in the fuel cell based on the amount of water in the oxidant gas after the reaction of the fuel cell; A discharge water amount prediction means for predicting the amount of water discharged from the oxidant electrode side in the fuel cell when the fuel cell is stopped during the start-up process based on a physical quantity,
From the difference between the existing water amount calculated by the existing water amount calculating means and the predicted discharged water amount predicted by the discharged water amount predicting means, residual water remaining on the oxidizer electrode side in the fuel cell after the fuel cell is stopped Predicting the quantity,
A fuel cell system. The fuel cell system according to claim 1, wherein
The fuel cell system according to claim 1, wherein the physical amount of the oxidant gas after the reaction is a water amount, a pressure, a temperature, and a flow rate of the oxidant gas after the reaction. The fuel cell system according to claim 1 or 2,
The fuel cell starting means sets the pressure of the oxidant gas supplied to the fuel cell by the pressure control valve when the temperature of the fuel cell is in a predetermined temperature range in the low temperature starting process of the fuel cell. A fuel cell system, wherein the fuel cell is started with a lower operating pressure.

Images