JP2007018781A - Fuel cell system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fuel cell system capable of preventing a fuel cell from coming into a high potential state close to an open circuit potential and of providing high load responsiveness when the fuel cell moves to high load operation. <P>SOLUTION: This fuel cell system includes: the fuel cell 110 for generating power by being supplied with hydrogen and oxygen; and a water electrolyzation device 130 electrically connected to a storage battery; when the fuel cell 110 moves from a high-load operation to a low-load operation, the fuel cell consumes surplus power separately from storage to the storage battery; and hydrogen and oxygen generated from the water electrolyzation device 130 are supplied to the fuel cell 110 when the fuel cell moves to the high-load operation again, whereby high load responsiveness can be provided. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a fuel cell system. The present invention particularly relates to a fuel cell system in which a water electrolysis device is electrically connected to a fuel cell.

  In recent years, the use of fuel cells for electric vehicles, household power supplies, mobile phones, notebook PCs, and the like is being put into practical use. Among fuel cells, in particular, a fuel cell using a polymer electrolyte membrane that can operate at room temperature is of interest.

  In order to prevent deterioration of the polymer electrolyte and dissolution of platinum as a catalyst, it is necessary for the fuel cell using the polymer electrolyte to avoid that the air electrode of the fuel cell is in a high potential state close to an open circuit potential. is there.

  In the fuel cell system disclosed in the following Patent Document 1, when power generation is stopped, the supply of the fuel gas to the fuel electrode is stopped after the supply of the oxidizing gas to the air electrode is stopped. By controlling in this way, the fuel gas is supplied to the air electrode through the polymer electrolyte layer while oxidizing gas is consumed, so that the potential difference between the air electrode and the fuel electrode is reduced, and the air electrode of the fuel cell has a high potential. The time required for the state can be shortened.

Patent Document 2 below discloses a technique in which water is electrolyzed using a household power source and the generated hydrogen gas is used as a fuel gas for a fuel cell.
JP 2004-172105 A JP 2005-032611 A

  However, in the fuel cell system having the above control method, it takes time for the fuel gas to permeate the polymer electrolyte membrane.

  Therefore, when used for a power source of an electric vehicle or the like, since start and stop and load fluctuation are frequently executed, the air electrode of the fuel cell is substantially in a high potential state, and deterioration of the polymer electrolyte and catalyst are caused. There is a possibility that dissolution of certain platinum may become remarkable. Furthermore, there is a problem that the load responsiveness is lowered with respect to a rapid load change at the time of starting the vehicle.

  The present invention has been made to solve the above-described problems. Therefore, an object of the present invention is to avoid the fuel cell air electrode from being in a high potential state close to an open circuit potential, and to obtain a high load responsiveness when the fuel cell shifts to a high load operation. It is to provide a fuel cell system.

  The above object of the present invention is achieved by the following means.

  The fuel cell system of the present invention has a water electrolyzer that is electrically connected to a fuel cell and a storage battery that generate power by receiving supply of hydrogen and oxygen, and the fuel cell is changed from a high load operation to a low load operation. High load response is achieved by consuming surplus power separately from the power storage in the storage battery, and supplying hydrogen and oxygen generated from the water electrolysis device when the fuel cell shifts to high load operation again. It is characterized in that it can be obtained.

  According to the fuel cell system of the present invention, since the surplus power generated by the fuel cell is consumed by the water electrolysis device, it can be avoided that the air electrode of the fuel cell is in a high potential state close to the open circuit potential. . Therefore, deterioration of the polymer electrolyte and dissolution of platinum as a catalyst can be reduced, and the life of the fuel cell can be improved. Furthermore, high load responsiveness can be obtained by supplying hydrogen and oxygen generated from the water electrolysis device when the fuel cell again shifts to high load operation.

  Embodiments of the present invention will be described below with reference to the drawings. In the following embodiments, a case where the present invention is applied to a power supply system for a vehicle driving motor will be described as an example. In the figure, the same symbols are used for similar members.

(First embodiment)
FIG. 1 is a block diagram showing a schematic configuration of a fuel cell system according to a first embodiment of the present invention.

  As shown in FIG. 1, the fuel cell system 100 of the present embodiment is connected to a load 200 and an auxiliary machine 300 via an inverter (not shown). The load 200 is a vehicle driving motor. The auxiliary machine 300 is a device necessary for power generation of the fuel cell 110 such as a compressor, a cooling water supply pump, and a pure water supply pump. The fuel cell system 100 includes a fuel cell 110, a storage battery 120, a water electrolysis device 130, a detection unit 140, a control unit 150, and a power distribution unit 160.

  The fuel cell 110 is supplied with hydrogen and oxygen to generate electric power. The fuel cell 110 is configured by stacking a plurality of unit cells. When the electric power generated by the fuel cell 110 is not completely consumed by the load 200 and the auxiliary machine 300, and the fuel cell 110 generates excessive electric power, the air electrode potential of the fuel cell 110 rises.

  The storage battery 120 consumes surplus power out of the power generated by the fuel cell 110. The storage battery 120 is connected in parallel to the fuel cell 110 via the power distribution unit 160. The storage battery 120 is also used for energy recovery when the regenerative brake is used, apart from excessive power consumption. Therefore, it is not preferable to fully charge the storage battery 120 only with the surplus power of the fuel cell 110. Usually, a predetermined upper limit is set for the amount of charge of the storage battery 120, and the storage battery 120 is prevented from being fully charged.

  The water electrolysis device 130 is an electrochemical device that consumes surplus power out of the power generated by the fuel cell 110 separately from the storage battery 120. The water electrolysis apparatus 130 is electrically connected in parallel to the fuel cell 110 via the power distribution unit 160. A detailed description of the water electrolysis apparatus 130 will be described later. Note that the expression “electrically connected” in this specification includes both the case of being directly connected and the case of being connected via another member (for example, the power distribution unit 160).

  The detection unit 140 includes a charge amount detection unit 140a and a potential detection unit 140b. The charge amount detection unit 140 a is a charge amount detection unit that detects the charge amount of the storage battery 120. The charge amount detection unit 140 a includes a current sensor attached to the storage battery 120. The potential detector 140 b is a potential detector that detects the air electrode potential of the fuel cell 110. The potential detection unit 140b includes a voltage sensor attached to the fuel cell 110. Furthermore, the detection unit 140 includes a load detection unit (not shown) that is a load detection unit that detects a required load on the fuel cell 110.

  Control unit 150 is a control unit that receives signals from detection unit 140 and controls storage battery 120, water electrolysis device 130, power distribution unit 160, and auxiliary machine 300 based on these signals. More specifically, the control unit 150 distributes the electric power generated by the fuel cell 110 to the storage battery 120, the water electrolysis device 130, the load 200, and the auxiliary machine 300 via the power distribution unit 160. The power distribution unit 160 is, for example, a general power distributor.

  Next, the connection relationship between the fuel cell 110 and the water electrolysis apparatus 130 in the present embodiment will be described with reference to FIG. For convenience of explanation, the power distribution unit 160 is omitted in FIG.

  As shown in FIG. 2, the fuel cell system 100 according to the present embodiment is electrically connected to the fuel cell 110 that is supplied with hydrogen and oxygen and generates electric power, and is connected to the fuel cell 110. And the water electrolysis device 130 that consumes surplus power separately from the storage battery 120.

  The water electrolyzer 130 electrolyzes water using surplus power generated by the fuel cell 110 to generate hydrogen and oxygen gas. The water electrolysis device 130 is electrically connected in parallel to the fuel cell 110 via the power distribution unit 160. The water electrolysis apparatus 130 has a pure water introduction pipe 133 to which water to be electrolyzed is supplied. One end of the pure water introduction pipe 133 is connected to the water electrolysis device 130, and the other end is connected to a pure water supply device (not shown).

  The fuel cell system 100 includes a hydrogen supply pipe (hydrogen gas supply line) 111a for supplying hydrogen gas to the fuel electrode of the fuel cell 110 and an air supply pipe (oxygen gas supply line) 112a for supplying air containing oxygen to the air electrode. Have One end of the hydrogen supply pipe 111 a is connected to the fuel electrode of the fuel cell 110. The other end of the hydrogen supply pipe 111a is connected to a hydrogen supply device (not shown). Similarly, one end of the air supply pipe 112a is connected to the air electrode of the fuel cell 110, and the other end is connected to an air supply device (not shown). The fuel cell system 100 also includes a hydrogen discharge pipe 111b that discharges hydrogen gas and an air discharge pipe 112b that discharges air.

  Further, the fuel cell system 100 has a gas supply pipe that supplies hydrogen and oxygen gas generated by the water electrolysis device 130 to the fuel cell 110. More specifically, the fuel cell system 100 includes an electrolytic hydrogen supply pipe 131 that supplies hydrogen gas generated by the water electrolysis apparatus 130 to the fuel cell 110 and an oxygen supply pipe 132 that supplies oxygen gas to the fuel cell 110. One end of the electrolytic hydrogen supply pipe 131 is connected to the water electrolysis apparatus 130. The other end of the electrolytic hydrogen supply pipe 131 is connected to the hydrogen supply pipe 111a. Similarly, one end of the oxygen supply pipe 132 is connected to the water electrolysis apparatus 130, and the other end is connected to the air supply pipe 112a.

  The electrolytic hydrogen supply pipe 131 which is a gas supply pipe is provided with a hydrogen buffer tank 121 for storing hydrogen gas. Similarly, the oxygen supply pipe 132 is provided with an oxygen buffer tank 122 for storing oxygen gas. Further, a hydrogen supply stop valve 141 is provided at a connection portion between the electrolytic hydrogen supply pipe 131 and the hydrogen supply pipe 111a. Similarly, an oxygen supply stop valve 142 is provided at a connection portion between the oxygen supply pipe 132 and the air supply pipe 112a.

  Next, with reference to FIG. 3, the structure of the electrolysis cell which forms the water electrolysis apparatus 130 in this fuel cell system 100 is demonstrated. In the present embodiment, the water electrolysis device 130 is a solid polymer type water electrolysis device using a solid polymer membrane as an electrolyte membrane.

  FIG. 3 is a cross-sectional view for explaining an electrolysis cell of a water electrolysis apparatus. As shown in FIG. 3, the electrolysis cell of the water electrolysis apparatus 130 is configured by stacking a plurality of electrolyte units 125. The electrolyte unit 125 includes a solid polymer electrolyte membrane 126, an electrode plate 127 provided so as to sandwich the solid polymer electrolyte membrane 126, a power feeder 128 provided between the solid polymer electrolyte membrane 126 and the electrode plate 127, and the like. Consists of. A description of the solid polymer electrolyte membrane 126, the electrode plate 127, and the power feeder 128 is omitted. Further, the number of stacked electrolyte units 125 is not limited to FIG.

  In the fuel cell system 100 of the present embodiment configured as described above, at least a part of surplus power among the power generated by the fuel cell 110 is distributed to the water electrolysis device 130. The water electrolysis apparatus 130 consumes the distributed surplus power. Hereinafter, the processing in the fuel cell system 100 of the present embodiment will be described with reference to FIG.

  FIG. 4 is a flowchart showing power consumption processing of the fuel cell system in the present embodiment. In addition, the power consumption process shown below is a process performed at the time of starting of a vehicle and a low load transfer. When the vehicle is started, for example, the vehicle driving motor is idling. At the time of start-up, although the power required by the load 200 is small, the fuel cell 110 continues to generate power upon receiving the supply of hydrogen and air, so that surplus power is generated. Similarly, the time of low load transition is, for example, a state in which the throttle (accelerator) is returned to decelerate, and surplus power is generated. In the fuel cell 110 having surplus power, the air electrode potential rises, and the air electrode of the fuel cell 110 enters a high potential state.

  First, the control unit 150 calculates a required load of the vehicle (step S101). The required load is, for example, the output of the driving motor. The required load is calculated from a conversion table or the like based on the accelerator opening. The required load is not limited to the output of the drive motor, but includes the outputs of various devices other than the auxiliary machine 300 used in the vehicle. These required loads are detected by the load detector.

  Next, the predicted value of the air electrode potential of the unit cell of the fuel cell 110 is compared with a predetermined value (step S102). The predicted value of the air electrode potential is calculated from the required load calculated in the process of step S101, the power generation amount of the fuel cell 110 calculated from the supply amounts of hydrogen and air to the fuel cell 110, the current air electrode potential, and the like. Is done. If the predicted value of the air electrode potential is lower than the predetermined value (step S102: NO), the process is terminated because the air electrode of the fuel cell 110 is not in a high potential state. When the predicted value of the air electrode potential is higher than the predetermined value (step S102: YES), the process proceeds to step S103. The predetermined value can be set to 0.8 V, for example, based on the open circuit voltage (about 1.23 V) of the fuel cell.

  Next, the required power of the load 200 and the auxiliary machine 300 is compared with the generated power of the fuel cell 110 (step S103). When the required power is larger than the generated power (step S103: NO), the control unit 150 maintains a state where power is distributed only to the load 200 and the auxiliary machine 300 (step S104). In other words, control unit 150 does not distribute power to storage battery 120 and water electrolysis device 130. The electric power generated by the fuel cell 110 can be consumed within a range where the load 200 and the auxiliary machine 300 are properly operated. When the required power is smaller than the generated power (step S103: YES), since surplus power is generated, the process proceeds to step S105. The power obtained by subtracting the generated power of the fuel cell 300 from the required power of the load 200 and the auxiliary machine 300 corresponds to the surplus power of the fuel cell 110.

  Next, the charge amount of the storage battery 120 is compared with the surplus power amount (step S105). As described above, the storage battery 120 is provided with a predetermined upper limit value in order to prevent full charge. When the predicted charge amount of storage battery 120 is smaller than the predetermined upper limit value (step S105: NO), control unit 150 distributes power to load 200, auxiliary machine 300, and storage battery 120 (step S106). As a result, surplus power is distributed to the storage battery 120 and consumed. When the amount of charge of storage battery 120 is greater than the predetermined upper limit (step S105: YES), control unit 150 distributes power to load 200, auxiliary machine 300, storage battery 120, and water electrolysis device 130 (step S107). . Specifically, the control unit 150 distributes the power stored in the surplus power up to the upper limit value to the storage battery 120 and distributes the remaining power to the water electrolysis device 130. Excess power is consumed by both the storage battery 120 and the water electrolysis device 130.

  Next, the air electrode potential of the fuel cell 110 is compared with a predetermined value (step S108). If the air electrode potential of the fuel cell 110 is lower than a predetermined value (for example, 0.8 V), the process is terminated. When the air electrode potential is higher than the predetermined value, the processes in and after step S103 are repeated.

  As described above, in the flowchart shown in FIG. 4, surplus power among the power generated by the fuel cell 110 is consumed by the water electrolysis device 130 separately from the storage battery 120. Therefore, it is avoided that the air electrode of the fuel cell 110 is in a high potential state at the time of starting the vehicle and shifting to a low load. At this time, the hydrogen supply stop valve 141 and the oxygen supply stop valve 142 provided in the electrolytic hydrogen supply pipe 131 and the oxygen supply pipe 132 are in a closed state. Therefore, hydrogen gas and oxygen gas generated in the water electrolysis apparatus 130 are stored in the buffer tanks 121 and 122 and are not supplied to the fuel cell 110.

  Next, a process for supplying hydrogen gas and oxygen gas generated in the water electrolysis apparatus 130 to the fuel cell 110 will be described. The gas supply process described below is a process executed particularly when the vehicle is shifted to a high load (acceleration).

  FIG. 5 is a flowchart showing a gas supply process of the fuel cell system in the present embodiment. At the time of high load transition where the vehicle after starting starts running, the fuel cell 110 causes a delay in output with respect to rapid load fluctuations when the vehicle starts. The fuel cell system 100 supplies high-pressure gas to the fuel cell 110 during high load transition to improve the output and suppress the shortage of the output of the fuel cell 110. In other words, the fuel cell system 100 according to the present embodiment further has a function of opening and closing the valves 141 and 142 in response to load fluctuations of the fuel cell 110.

  First, the control unit 150 detects a required load (step S201). Next, the control unit 150 determines whether or not the detected load shifts from a low load to a high load (step S202). More specifically, for example, the control unit 150 determines that the load shifts from a low load to a high load when the load fluctuation amount is larger than a predetermined value. The predetermined value can be appropriately selected depending on the motor and the running characteristics of the vehicle. In the case of transition from low load to high load (step S202: YES), the process proceeds to step S204. When not shifting from a low load to a high load (step S202: NO), it is determined whether or not to stop the operation (step S203). When the operation is not stopped (step S203: NO), the processing from step S201 is repeated. If the operation is to be stopped (step S203: YES), the process is terminated.

  Next, the control unit 150 opens the supply stop valves 141 and 142 to supply hydrogen and oxygen gas generated in the water electrolysis device 130 (step S204). As a result, high-pressure hydrogen and oxygen gas are supplied to the fuel cell 110, and the instantaneous output of the fuel cell 110 is improved as compared to the normal gas supply.

  Next, the control unit 150 determines whether or not the shift to the required load is completed (step S205). The transition to the required load is completed when, for example, the vehicle reaches a desired speed. When the transition to the required load is completed (step S205: YES), the process proceeds to step S206. When the shift to the required load is not completed (step S205: NO), the supply stop valves 141 and 142 are kept open until the shift to the required load is completed.

  Finally, the control unit 150 closes the supply stop valves 141 and 142 (step S206) and ends the process.

  As described above, in the flowchart shown in FIG. 5, since the hydrogen and oxygen gas stored in the electrolytic hydrogen supply pipe 131 and the oxygen supply pipe 132 are supplied to the fuel cell 110 under high pressure, the instantaneous output of the fuel cell 110 Will improve. Therefore, insufficient output of the fuel cell 110 is suppressed when the vehicle starts. That is, when the fuel cell 110 shifts from the high load operation to the low load operation, the fuel cell system 100 of the present embodiment consumes surplus power separately from the power storage in the storage battery 120, and the water electrolysis device 130 High load responsiveness can be obtained by supplying the generated hydrogen and oxygen when the fuel cell 110 shifts to high load operation again.

  As described above, the described embodiment has the following effects.

  The fuel cell system of the present invention includes a water electrolysis device that consumes surplus power out of the power generated by the fuel cell separately from the storage battery. Therefore, it is avoided that the air electrode of the fuel cell is in a high potential state, and the deterioration of the electrolyte membrane of the fuel cell and the dissolution of platinum are reduced. As a result, the life of the fuel cell can be improved.

  A potential detecting means for detecting the air electrode potential of the fuel cell; and a control means for distributing at least a part of surplus power to the water electrolysis device and controlling the air electrode potential of the fuel cell to a predetermined value or less. Have. Therefore, surplus power can be consumed based on the air electrode potential of the fuel cell.

  The control means distributes the surplus power to the storage battery, and further distributes the power stored in the surplus power up to the upper limit value to the storage battery when the charge amount of the storage battery becomes larger than the predetermined upper limit value. Is distributed to the water electrolyzer. Therefore, unlike the case where the storage battery and the auxiliary machine are given more electric power than necessary to lower the air electrode potential, the storage battery and the auxiliary machine can be operated under efficient and optimal operating conditions.

  The water electrolysis apparatus electrolyzes water using surplus power generated by the fuel cell to generate hydrogen and oxygen gas. Accordingly, surplus electric power is consumed, and hydrogen and oxygen generated by electrolysis can be supplied again to the fuel cell and reused, thereby improving the efficiency of the fuel cell system. Moreover, the water electrolysis apparatus is widely used industrially, and can generate hydrogen and oxygen gas efficiently.

  The water electrolysis apparatus is a solid polymer type water electrolysis apparatus. Therefore, a small water electrolysis device is used, and the fuel cell system can be miniaturized. Moreover, the pure water etc. which are used for a fuel cell can be diverted.

  A gas supply pipe is provided for supplying hydrogen and oxygen gas generated in the water electrolysis apparatus to the fuel cell. Therefore, the gas generated by the water electrolysis device when the vehicle is idle can be stored, and high-pressure hydrogen and oxygen gas can be supplied to the fuel cell as necessary. That is, high load responsiveness can be obtained by supplying hydrogen and oxygen generated from the water electrolysis device when the fuel cell again shifts to high load operation. As a result, a delay in the output of the fuel cell with respect to a sudden load change at the start of the vehicle is prevented, and the vehicle can be accelerated stably.

  It has a buffer tank for storing hydrogen and oxygen gas. Therefore, it is possible to prevent the electrolytic hydrogen from the water electrolysis device to the fuel cell and the hydrogen and oxygen gas in the oxygen supply pipe from being excessively pressurized.

(Second Embodiment)
In the first embodiment, the case where the hydrogen and oxygen gas generated by the water electrolysis apparatus is stored in the buffer tank has been described. In the present embodiment, a case will be described in which hydrogen and oxygen gas generated by the water electrolysis device are stored in the hydrogen and oxygen supply pipe without providing a special buffer tank.

  FIG. 6 is a diagram for explaining a connection relationship between the fuel cell and the water electrolysis apparatus in the second embodiment of the present invention.

  As shown in FIG. 6, the fuel cell system 100 of the present embodiment includes pressure adjustment valves 151 and 152 that are provided in the gas supply pipe and adjust the pressure of the gas supply pipe. More specifically, the gas supply pipe is composed of a first electrolytic hydrogen supply pipe 131a, a second electrolytic hydrogen supply pipe 131b, a first oxygen supply pipe 132a, and a second oxygen supply pipe 132b.

  One end of the first electrolytic hydrogen supply pipe 131a is connected to the water electrolysis apparatus 130, and the other end is connected to the hydrogen supply pipe 111a. A first supply stop valve 141 is provided at a connection portion between the first electrolytic hydrogen supply pipe 131a and the hydrogen supply pipe 111a. A second supply stop valve 171 is provided in the first electrolytic hydrogen supply pipe 131a. Further, one end of the second electrolytic hydrogen supply pipe 131b is connected to the first electrolytic hydrogen supply pipe 131a on the upstream side (that is, the water electrolysis apparatus 130 side) from the second supply stop valve 171. The other end of the second electrolytic hydrogen supply pipe 131b is connected to the hydrogen supply pipe 111a on the upstream side (that is, the hydrogen supply apparatus side) of the first electrolytic hydrogen supply pipe 131a. The second electrolytic hydrogen supply pipe 131b is provided with a pressure adjustment valve 151 and a check valve 161 from the upstream side (that is, the water electrolysis apparatus 130 side). Since the configuration of the gas supply pipe is the same except that the supplied gas is oxygen, the description regarding the first and second oxygen supply pipes 132a and 132b is omitted.

  In the fuel cell system 100 of the present embodiment configured as described above, the pressure in the electrolytic hydrogen and oxygen supply pipes 131a and 132a is prevented from becoming excessive. More specifically, when the pressure in the gas supply pipe for supplying hydrogen and oxygen generated from the water electrolysis apparatus 130 to the fuel cell 110 becomes equal to or higher than a predetermined pressure, the pressure adjustment valves 151 and 152 are opened to cause excessive pressure. To prevent it. Furthermore, in the fuel cell system 100 of the present embodiment, hydrogen and oxygen gas supplied to the electrolytic hydrogen and oxygen supply pipes 131b and 132b via the pressure regulating valves 151 and 152 are supplied with hydrogen. It can be accumulated in the pipe 111a and the air supply pipe 112a.

  As described above, the described embodiment has the following effects in addition to the effects of the first embodiment.

  The fuel cell system of the present invention includes a pressure adjusting valve that is provided in a gas supply pipe and adjusts the pressure in the gas supply pipe. Therefore, it is possible to prevent the pressure in the electrolytic hydrogen and oxygen supply piping from becoming excessive. Further, hydrogen and oxygen gas generated in the water electrolysis apparatus can be accumulated in the hydrogen supply pipe and the air supply pipe that are not supplied.

(Third embodiment)
This embodiment is an embodiment in which a plurality of water electrolysis devices are connected to a fuel cell in the present fuel cell system.

  FIG. 7 is a block diagram showing a schematic configuration of a fuel cell system according to the third embodiment of the present invention. As shown in FIG. 7, the fuel cell system 100 includes a plurality of water electrolyzers 130a and 130b, and the water electrolyzers 130a and 130b are selectively used according to the amounts of hydrogen and oxygen gas to be generated. Can be done.

  More specifically, the fuel cell system 100 includes a plurality of water electrolyzers 130a and 130b, and water electrolyzers 130a and 130a that distribute power according to the amounts of hydrogen and oxygen gas to be generated. 130b can be switched.

  In the present embodiment, the fuel cell system 100 includes a first water electrolyzer 130a and a second water electrolyzer 130b. In the present embodiment, for example, the water electrolysis capability of the first water electrolysis device 130a is higher than the water electrolysis capability of the second water electrolysis device 130b. The water electrolysis capacity indicates the amount of hydrogen and oxygen gas generated per electric power consumed.

  In the fuel cell system 100 of the present embodiment configured as described above, the first water electrolyzer 130a and the first water electrolyzer 130a are arranged in accordance with the amount of gas that can be stored in the gas supply pipe (including the buffer tanks 121 and 122). The second water electrolysis device 130b is switched. When the amount of gas that can be stored in the gas supply pipes 131 and 132 is small, surplus power is supplied only to the second water electrolyzer 130b having a low water electrolysis capacity. When the amount of gas that can be stored in the gas supply pipe is large, surplus power can be supplied to the first water electrolysis device 130a having high water electrolysis capability.

  Further, unlike the present embodiment, the fuel cell system 100 can also change the number of water electrolyzers that distribute power according to the amounts of hydrogen and oxygen gas to be generated. More specifically, for example, in the present embodiment, the first and second water electrolyzers 130a and 130b may have the same water electrolysis capacity. In this case, the amount of hydrogen and oxygen gas to be generated can be adjusted by supplying surplus power to both or only one of the first and second water electrolyzers 130a and 130b.

  As described above, the described embodiment has the following effects in addition to the effects of the first and second embodiments.

  The fuel cell system of the present invention has a plurality of water electrolysis devices, and the plurality of water electrolysis devices are selectively used according to the amounts of hydrogen and oxygen gas to be generated. Therefore, it is possible to prevent the pressure in the gas supply pipe from increasing.

  As described above, the fuel cell system of the present invention has been described in the first to third embodiments. However, it goes without saying that the present invention can be appropriately added, modified, and omitted by those skilled in the art within the scope of the technical idea.

  For example, the control unit distributes surplus power to the storage battery, and further distributes, to the storage battery, power that is stored up to the upper limit value among the surplus power when the charge amount of the storage battery becomes larger than a predetermined upper limit value. Distribute the remaining power to the water electrolyzer. However, when it is predicted that the charge amount of the storage battery will be larger than the predetermined upper limit value, all of the surplus power may be distributed to the water electrolysis device.

  Further, in the fuel cell system of the present invention, processing by feedforward control is executed to predict the air electrode potential of fuel ionization. However, processing based on feedback control may be executed when the air electrode potential of the fuel cell exceeds a predetermined value, or when surplus power exceeds a predetermined upper limit value of the storage battery.

1 is a block diagram showing a schematic configuration of a fuel cell system according to a first embodiment of the present invention. It is a figure for demonstrating the connection relation of the fuel cell and water electrolysis apparatus in the fuel cell system shown in FIG. It is sectional drawing for demonstrating the electrolysis cell of the water electrolysis apparatus in the fuel cell system shown in FIG. It is a flowchart which shows the power consumption process of the fuel cell system shown in FIG. It is a flowchart which shows the gas supply process of the fuel cell system shown in FIG. It is a figure for demonstrating the connection relation of the fuel cell and water electrolysis apparatus in the 2nd Embodiment of this invention. It is a block diagram which shows schematic structure of the fuel cell system in the 3rd Embodiment of this invention.

Explanation of symbols

100 fuel cell system,
110 Fuel cell,
120 storage battery,
121, 122 buffer tank,
130 water electrolyzer,
131 Electrolytic hydrogen supply piping,
132 oxygen supply piping,
140 detector,
150 control unit,
151,152 pressure regulating valve,
160 power distribution unit,
200 load,
300 Auxiliary equipment.

Claims (8)

  A fuel cell that receives power from hydrogen and oxygen to generate electric power and a water electrolysis device that is electrically connected to the storage battery. When the fuel cell shifts from high load operation to low load operation, It is characterized in that a high load responsiveness is obtained by consuming surplus power separately from power storage and supplying hydrogen and oxygen generated from the water electrolysis device when the fuel cell again shifts to high load operation. Fuel cell system.   Distributing at least part of the surplus power to the water electrolysis device, load detection means for detecting a required load on the fuel cell, potential detection means for detecting an air electrode potential of the fuel cell, and The fuel cell system according to claim 1, further comprising control means for controlling the air electrode potential of the fuel cell to a predetermined value or less.   A charge amount detecting means for detecting a charge amount of the storage battery; and the control means distributes the surplus power to the storage battery, and the charge amount of the storage battery is greater than a predetermined upper limit value. 3. The fuel cell system according to claim 2, wherein electric power stored up to the upper limit value among the surplus electric power is distributed to the storage battery, and the remaining electric power is distributed to the water electrolysis device.   The fuel cell system according to claim 1, wherein the water electrolysis device is a solid polymer type water electrolysis device using a solid polymer membrane as an electrolyte membrane.   Gas supply piping for supplying hydrogen and oxygen gas generated in the water electrolysis device to the fuel cell is connected to the gas supply lines of the hydrogen electrode and the air electrode via a valve to cope with load fluctuations of the fuel cell. The fuel cell system according to claim 1, further comprising a function of opening and closing the valve.   6. The fuel cell system according to claim 5, further comprising a buffer tank provided in the gas supply pipe for storing the hydrogen and oxygen gas.   The gas supply pipe is provided with a pressure adjustment valve for adjusting the pressure of the gas supply pipe, and the gas supply pipe for supplying hydrogen and oxygen generated from the water electrolysis device to the fuel cell has a predetermined pressure or higher. 6. The fuel cell system according to claim 5, wherein the pressure regulating valve is prevented from opening and becoming an excessive pressure in the case of becoming. The fuel cell system has a plurality of water electrolysis devices,
2. The fuel cell system according to claim 1, wherein the plurality of water electrolysis apparatuses are selectively used according to the amounts of hydrogen and oxygen gas to be generated.

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