JP2011096554A - Fuel cell system and transportation apparatus having the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fuel cell system capable of restraining reduction of power generation efficiency. <P>SOLUTION: The fuel cell system includes a cell stack. The cell stack includes a fuel cell having an anode and a cathode. A CPU controls the amount of air supply to the cathode by an air pump to be increased, every time the time of power generation of the cell stack exceeds a first predetermined time. The CPU also sets a second predetermined time based on a total power generating time, and drives the air pump for the second predetermined time after stopping a water solution pump on the occasion of stopping power generation of the cell stack. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a fuel cell system and a transport device including the same, and more particularly to a direct methanol fuel cell system and a transport device including the same.

  2. Description of the Related Art Generally, a fuel cell system is known that performs a power generation reaction by supplying fuel to an anode of a fuel cell and air to a cathode of the fuel cell. In this power generation reaction, water is generated on the cathode side. In addition, in a fuel cell system using a liquid such as an aqueous methanol solution as a fuel, the aqueous fuel solution may permeate a member such as an electrolyte membrane that separates the anode and the cathode in addition to water generated at the cathode. When so-called flooding occurs in which the generated water or the permeated aqueous fuel solution covers the surface of the cathode where the power generation reaction occurs, the power generation reaction may be hindered and the output power of the fuel cell may be reduced.

Patent Document 1 discloses that the amount of air supplied to the cathode is increased when a problem that the liquid covers the surface of the cathode is detected (see paragraph 0047).
JP 2006-210070 A

  However, in Patent Document 1, if the air supply amount by the air pump is increased at a stroke after detecting flooding, the power consumption of the air pump increases rapidly, so that the net output power decreases and the power generation efficiency decreases.

  Therefore, a main object of the present invention is to provide a fuel cell system capable of suppressing a decrease in power generation efficiency.

  In order to achieve the above object, a fuel cell system according to claim 1 includes a fuel cell having an anode and a cathode, and a gas supply unit for supplying a gas containing an oxidant to the cathode of the fuel cell; An information acquisition unit that acquires correlation information correlated with the output power of the fuel cell, and a control unit that controls a gas supply amount by the gas supply unit based on the correlation information acquired by the information acquisition unit, Is characterized in that the gas supply amount by the gas supply unit is increased every time the correlation information indicates a decrease in the output power of the fuel cell.

  The fuel cell system according to claim 2 is the fuel cell system according to claim 1, wherein the correlation information includes a power generation time of the fuel cell, and the control unit gasses the power generation time every time the first predetermined time elapses. The gas supply amount by the supply unit is increased.

  The fuel cell system according to claim 3 is the fuel cell system according to claim 1, wherein the correlation information includes information related to the output power of the fuel cell, and the control unit reduces the information related to the output power of the fuel cell by a predetermined amount. The gas supply amount by the gas supply unit is increased every time.

  A fuel cell system according to a fourth aspect of the present invention is the fuel cell system according to the first aspect, further comprising an aqueous solution supply unit that supplies an aqueous fuel solution to the anode of the fuel cell, and the control unit stops power generation of the fuel cell. In this case, the gas supply unit is driven for a second predetermined time after the aqueous solution supply unit is stopped.

  The fuel cell system according to claim 5 is the fuel cell system according to claim 4, further comprising a time acquisition unit for acquiring a total power generation time from the start of power generation of the fuel cell, wherein the control unit is A second predetermined time is set based on the acquired total power generation time.

  A transportation device according to a sixth aspect includes the fuel cell system according to any one of the first to fifth aspects, and an electric motor to which electric power is supplied from the fuel cell system.

  In the fuel cell system according to the first aspect, the gas supply amount by the gas supply unit is increased each time a decrease in the output power of the fuel cell is recognized based on the correlation information acquired by the information acquisition unit. As a result, the gas supply amount by the gas supply unit can be set to a small value for a while from the start of power generation of the fuel cell, and then gradually increased. Therefore, the fuel having the property of gradually increasing the saturated vapor pressure in the cathode of the fuel cell and promoting the vaporization of the liquid in the cathode and promoting the discharge of the liquid from the cathode and gradually progressing with time. The progress of battery flooding can be suppressed. As a result, it is possible to suppress a decrease in output power of the fuel cell and prevent a decrease in power generation efficiency while preventing waste of electric power due to a rapid increase in the amount of gas supplied by the gas supply unit.

  In general, since the flooding of the fuel cell gradually proceeds with time, the output power of the fuel cell gradually decreases with time. Therefore, there is a strong correlation between the elapsed time from the start of power generation by the fuel cell and the output power of the fuel cell. In the fuel cell system according to claim 2, it is considered that the output power of the fuel cell decreases every time the power generation time of the fuel cell passes the first predetermined time, and the gas supply amount by the gas supply unit is determined by a predetermined amount. Increase it step by step. Thereby, the gas supply amount by the gas supply unit can be easily controlled, and the gas supply amount by the gas supply unit can be periodically increased from the start of power generation. As a result, the discharge of the liquid present in the cathode can be promoted, and the decrease in the output power of the fuel cell can be suppressed.

  The fuel cell system according to claim 3 detects information related to the output power of the fuel cell, and increases the gas supply amount by the gas supply unit by a predetermined amount each time the value decreases by a predetermined amount (for example, a predetermined amount or a predetermined ratio). Let As a result, the amount of gas supplied by the gas supply unit can be accurately controlled, and a decrease in the output power of the fuel cell can be more reliably suppressed.

  In the fuel cell system according to claim 4, when stopping the power generation of the fuel cell, after stopping the aqueous solution supply unit, the gas supply unit is driven for a second predetermined time. As a result, more cathode liquid can be discharged at the end of power generation than when the aqueous solution supply unit and the gas supply unit are stopped simultaneously. Thereby, it is possible to lengthen the time until flooding occurs in the next power generation.

  The amount of liquid present in the cathode tends to change according to the length of the total power generation time, which is the elapsed time from the start of power generation of the fuel cell. Therefore, in the fuel cell system according to the fifth aspect, the second predetermined time corresponding to the amount of the liquid present in the cathode is set based on the total power generation time of the fuel cell. Then, after stopping the aqueous solution supply unit, the gas supply unit is driven for the set second predetermined time. As a result, waste of electric power required for driving the gas supply unit can be prevented.

  Since transportation equipment is susceptible to vibrations and the like due to external forces during operation, flooding is likely to occur when a fuel cell system is mounted on the transportation equipment. According to the present invention, the occurrence of flooding can be suppressed and the decrease in power generation efficiency can be suppressed. Therefore, the present invention is suitably used for transportation equipment including a fuel cell system as described in claim 6.

  Note that “correlation information having a correlation with the output power of the fuel cell” refers to information with which it is possible to recognize whether or not the output power of the fuel cell is decreasing based on the information. When the output power of the fuel cell is decreasing, the information is increasing or decreasing. Examples of the correlation information include power generation time of the fuel cell, information related to the output power of the fuel cell, and power generation efficiency of the fuel cell. The power generation efficiency of the fuel cell can be obtained based on the amount of fuel replenished per unit time to the aqueous solution tank and the temperature of the discharge from the anode outlet and cathode outlet of the fuel cell.

  Examples of the “information regarding the output power of the fuel cell” include the output power, output voltage, and output current of the fuel cell itself, and the output power, output voltage, and output current of the cell stack.

  According to this invention, it is possible to suppress a decrease in power generation efficiency of the fuel cell system.

1 is a left side view showing a motorcycle according to an embodiment of the present invention. It is a system diagram showing piping of a fuel cell system of one embodiment of this invention. It is a block diagram which shows the electric constitution of the fuel cell system of one Embodiment of this invention. It is a flowchart which shows an example of operation | movement of one Embodiment of this invention. It is a table which shows the relationship between total electric power generation time and 2nd predetermined time. (A) is a graph showing the gross output power of the cell stack in the conventional example, and (b) is the gross output power and net output power of the cell stack and the auxiliary machine power consumption in the case of performing the operation of FIG. 4 and the conventional example. It is a graph which shows. It is a flowchart which shows the other example of operation | movement of one Embodiment of this invention. (A) is a graph showing the gross output power of the cell stack in the conventional example, and (b) is the gross output power and net output power and auxiliary power consumption of the cell stack in the case of performing the operation of FIG. 7 and the conventional example. It is a graph which shows.

Embodiments of the present invention will be described below with reference to the drawings.
Here, a case where the fuel cell system 100 of the present invention is mounted on a motorcycle 10 which is an example of a transportation device will be described.

  First, the motorcycle 10 will be described. Left and right, front and rear, and top and bottom in the embodiment of the present invention mean left and right, front and back, and top and bottom with respect to a state in which the driver is seated on the seat of the motorcycle 10 toward the handle 24.

  Referring to FIG. 1, a motorcycle 10 has a body frame 12. The vehicle body frame 12 includes a head pipe 14, a front frame 16 extending obliquely downward from the head pipe 14 to the rear, and a rear frame 18 connected to a rear end portion of the front frame 16 and rising obliquely upward to the rear. A seat rail 20 for fixing a seat (not shown) is fixed to the upper end portion of the rear frame 18.

  A steering shaft 22 is rotatably inserted into the head pipe 14. A handle support portion 26 to which a handle 24 is fixed is attached to the upper end of the steering shaft 22. A display operation unit 28 is disposed at the upper end of the handle support unit 26.

  Referring also to FIG. 3, display operation unit 28 includes an input unit 28 a for inputting various instructions and various information, and a display unit 28 b configured by, for example, a liquid crystal display for providing various information. The input unit 28a includes a forced stop switch 28c for stopping power generation of the cell stack 102 and the fuel cell 104, which will be described later.

  As shown in FIG. 1, a pair of left and right front forks 30 are attached to the lower end of the steering shaft 22, and a front wheel 32 is rotatably attached to the lower ends of the pair of front forks 30.

  A swing arm (rear arm) 34 is swingably attached to the lower end portion of the rear frame 18. A rear end portion 34 a of the swing arm 34 includes, for example, an axial gap type electric motor 38 that is connected to the rear wheel 36 and that rotates the rear wheel 36. The swing arm 34 includes a drive unit 40 that is electrically connected to the electric motor 38. The drive unit 40 includes a motor controller 42 for controlling the rotational drive of the electric motor 38 and a storage amount detector 44 that detects a storage amount of a secondary battery 128 (described later).

  In such a motorcycle 10, components of the fuel cell system 100 are arranged along the body frame 12. The fuel cell system 100 generates electric energy for driving the electric motor 38, auxiliary machines, and the like.

Hereinafter, the fuel cell system 100 will be described with reference to FIGS. 1 and 2.
The fuel cell system 100 is a direct methanol fuel cell system that directly uses methanol (aqueous methanol solution) for generation (electric power generation) of electric energy without reforming.

  The fuel cell system 100 includes a fuel cell stack (hereinafter simply referred to as a cell stack) 102. As shown in FIG. 1, the cell stack 102 is suspended from the front frame 16 and disposed below the front frame 16.

  As shown in FIG. 2, the cell stack 102 includes a plurality of fuel cells (fuel cell) 104 that can generate electric power by an electrochemical reaction between hydrogen ions based on methanol and oxygen (oxidant). These fuel cells 104 are stacked (stacked) and connected in series. Each fuel cell 104 includes an electrolyte membrane 106 made of a solid polymer membrane, and an anode (fuel electrode) 108 and a cathode (air electrode) 110 facing each other with the electrolyte membrane 106 interposed therebetween. Each of the anode 108 and the cathode 110 has a platinum catalyst layer (not shown) on the electrolyte membrane 106 side. A separator 112 is sandwiched between adjacent fuel cells 104.

  As shown in FIG. 1, a radiator unit 114 is disposed below the front frame 16 and above the cell stack 102.

  As shown in FIG. 2, the radiator unit 114 is a unit in which an aqueous solution radiator 114a and a gas-liquid separation radiator 114b are integrally provided.

  A fuel tank 116, an aqueous solution tank 118, and a water tank 120 are disposed between the pair of plate members of the rear frame 18 in order from above.

  The fuel tank 116 contains a high-concentration (preferably containing about 50 wt% methanol) methanol fuel (high-concentration aqueous methanol solution) that serves as a fuel for the electrochemical reaction of the cell stack 102. The aqueous solution tank 118 contains a methanol aqueous solution obtained by diluting the methanol fuel from the fuel tank 116 to a concentration suitable for the electrochemical reaction of the cell stack 102 (preferably containing about 3 wt% of methanol). The water tank 120 contains water to be supplied to the aqueous solution tank 118.

  A level sensor 122 is attached to the fuel tank 116, a level sensor 124 is attached to the aqueous solution tank 118, and a level sensor 126 is attached to the water tank 120. The level sensors 122, 124, and 126 are, for example, float sensors, and detect the height (liquid level) of the liquid level in the tank.

  A secondary battery 128 is disposed on the front side of the fuel tank 116 and on the upper side of the front frame 16. The secondary battery 128 stores electric power from the cell stack 102 and supplies electric power to the electric components in accordance with instructions from a controller 136 (described later). A fuel pump 130 is disposed on the upper side of the secondary battery 128.

  In the storage space on the left side of the front frame 16, an aqueous solution pump 132 and an air pump 134 are stored. A controller 136 and a water pump 138 are arranged in the storage space on the right side of the front frame 16.

  A main switch 140 is provided on the front frame 16. When the main switch 140 is turned on, an operation start instruction is given to the controller 136, and when the main switch 140 is turned off, an operation stop instruction is given to the controller 136. When the main switch 140 is turned off during the power generation operation of the cell stack 102, an operation stop instruction and a power generation stop instruction are given to the controller 136.

  As shown in FIG. 2, the fuel tank 116 and the fuel pump 130 are communicated by a pipe P1, the fuel pump 130 and the aqueous solution tank 118 are communicated by a pipe P2, and the aqueous solution tank 118 and the aqueous solution pump 132 are communicated by a pipe P3. The aqueous solution pump 132 and the cell stack 102 are communicated with each other by a pipe P4. The pipe P4 is connected to the anode inlet I1 of the cell stack 102. An aqueous methanol solution is supplied to the cell stack 102 by driving the aqueous solution pump 132. The pipe P4 is provided with a concentration sensor 142 for detecting the concentration of the aqueous methanol solution (ratio of methanol in the aqueous methanol solution). For example, an ultrasonic sensor is used as the concentration sensor 142. The ultrasonic sensor detects a propagation time (propagation speed) of an ultrasonic wave that changes according to the concentration of the aqueous methanol solution as a voltage value. The controller 136 detects the concentration of the aqueous methanol solution based on the voltage value.

  A cell stack temperature sensor 144 is provided in the vicinity of the anode inlet I 1 of the cell stack 102. The cell stack temperature sensor 144 detects the temperature of the aqueous methanol solution, and regards it as the temperature of the cell stack 102 and the fuel cell 104.

The cell stack 102 and the aqueous solution radiator 114a are connected with each other by a pipe P5, and the radiator 114a and the aqueous solution tank 118 are connected with each other by a pipe P6. The pipe P5 is connected to the anode outlet I2 of the cell stack 102.
The pipes P1 to P6 described above mainly serve as fuel flow paths.

  In addition, a pipe P7 is connected to the air pump 134, and the air pump 134 and the cell stack 102 are communicated with each other by a pipe P8. The pipe P8 is connected to the cathode inlet I3 of the cell stack 102. By driving the air pump 134, air as a gas containing oxygen (oxidant) is supplied to the cell stack 102 from the outside. An outside air temperature sensor 146 that detects the outside air temperature is provided in the vicinity of the pipe P7.

The cell stack 102 and the gas-liquid separating radiator 114b are communicated by a pipe P9, the radiator 114b and the water tank 120 are communicated by a pipe P10, and the water tank 120 is provided with a pipe (exhaust pipe) P11. The pipe P9 is connected to the cathode outlet I4 of the cell stack 102. The pipe P11 is provided at the exhaust port of the water tank 120 and exhausts the exhaust from the cell stack 102 to the outside.
The pipes P7 to P11 described above mainly serve as an oxidant flow path.

The water tank 120 and the water pump 138 are communicated by a pipe P12, and the water pump 138 and the aqueous solution tank 118 are communicated by a pipe P13.
The pipes P12 and P13 described above serve as a water flow path.

Next, the electrical configuration of the fuel cell system 100 will be described with reference to FIG.
The controller 136 of the fuel cell system 100 includes a CPU 148, a clock circuit 150, a memory 152, a voltage detection circuit 154, a current detection circuit 156, an ON / OFF circuit 158, and a power supply circuit 160.

  The CPU 148 performs necessary calculations and controls the operation of the fuel cell system 100. The clock circuit 150 provides a clock signal to the CPU 148. The memory 152 includes, for example, an EEPROM, and stores programs, data, calculation data, and the like for controlling the operation of the fuel cell system 100. The voltage detection circuit 154 detects the voltage of the cell stack 102. The current detection circuit 156 detects a current flowing through the electric circuit 162. The ON / OFF circuit 158 opens and closes the electric circuit 162. The power supply circuit 160 supplies a predetermined voltage to the electric circuit 162.

  The CPU 148 of the controller 136 receives input signals from the main switch 140 and the input unit 28a. Further, detection signals from the level sensors 122, 124, 126, the concentration sensor 142, the cell stack temperature sensor 144, and the outside air sensor 146 are input to the CPU 148. Further, the voltage detection value from the voltage detection circuit 154 and the current detection value from the current detection circuit 156 are input to the CPU 148. The CPU 148 calculates the output power of the cell stack 102 based on the voltage detection value from the voltage detection circuit 154 and the current detection value from the current detection circuit 156.

  The CPU 148 controls auxiliary equipment such as the fuel pump 130, the aqueous solution pump 132, the air pump 134, and the water pump 138.

  Further, the CPU 148 controls the display unit 28b for notifying the driver of various information. Further, the CPU 148 controls an ON / OFF circuit 158 that opens and closes the electric circuit 162.

  The secondary battery 128 complements the output power of the cell stack 102, is charged by the output power of the cell stack 102, and supplies power to the electric motor 38, auxiliary machines, and the like by the discharge.

  The CPU 148 receives the stored amount detection value from the stored amount detector 44 via the interface circuit 164. CPU 148 calculates the storage rate of secondary battery 128 using the input storage amount detection value and the capacity of secondary battery 128.

  A memory 152 as a storage means stores a program for executing the operations of FIGS. 4 and 7, various calculation values, various detection values, and the like. Further, the memory 152 stores table data indicating the relationship between the total power generation time and the second predetermined time (purge time) shown in FIG. In FIG. 5, when the total power generation time is less than 1 hour, less than 2 hours, and less than 3 hours, the second predetermined time is 1 minute, 2 minutes, and 3 minutes, respectively. However, if the total power generation time becomes 3 hours or more, the second predetermined time remains 4 minutes. This is because the flooding is saturated when the total power generation time is 3 hours or more.

  In this embodiment, the control unit includes a CPU 148. The gas supply unit includes an air pump 134. The information acquisition unit includes a CPU 148, a clock circuit 150, a voltage detection circuit 154, and a current detection circuit 156. The aqueous solution supply unit includes an aqueous solution pump 132. The time acquisition unit includes a CPU 148 and a clock circuit 150.

An example of the operation of the fuel cell system 100 will be described with reference to FIG.
When the main switch 140 is turned on and the storage amount detector 44 detects that the storage rate of the secondary battery 128 is less than a predetermined value (preferably 40%), the power generation of the cell stack 102 and thus the fuel cell 102 is started. . At this time, the CPU 148 drives the aqueous solution pump 132 to supply the aqueous methanol solution to the anode 108 of the cell stack 102 and also drives the air pump 134 to supply air to the cathode 110 of the cell stack 102.

  When power generation is started in this way, the CPU 148 counts the power generation time of the cell stack 102 and thus the fuel cell 104 based on the signal from the clock circuit 150 (step S1). Counting the power generation time of the cell stack 102 is started when the power generation of the cell stack 102 is started. As will be described later, the power generation time is cleared to zero each time a first predetermined time (here, 1 hour) elapses, and the count from 0 to the first predetermined time is repeated.

  Then, the CPU 148 determines whether or not the power generation time of the cell stack 102 has passed a first predetermined time (here, 1 hour) (step S3). If the first power generation time has not elapsed, the CPU 148 counts the total power generation time, which is the time elapsed from the start of power generation in the cell stack 102, in order to set the second predetermined time (step S5). Then, the CPU 148 determines whether or not a power generation stop signal is given (step S7). When the forced stop switch 28c is turned off, a power generation stop signal is given to the CPU 148. Further, if the CPU 148 detects that the storage rate of the secondary battery 128 is equal to or higher than a predetermined value (for example, 98%) based on the output of the storage amount detector 44, it gives a power generation stop signal to itself. In step S7, if the power generation stop signal is not given to the CPU 148, the process returns to step S1. As long as steps S3 and S7 are NO, steps S1 to S7 are repeated.

  When the first predetermined time has elapsed in step S3, the CPU 148 increases the output of the air pump 134 and increases the amount of air supplied to the cathode 110 of the cell stack 102 by 5% (step S9). Then, the CPU 148 clears the power generation time to zero (step S11) and returns to step S1.

  On the other hand, if a power generation stop signal is given to the CPU 148 in step S7, the CPU 148 refers to the table data indicating the relationship of FIG. 5 stored in the memory 152 and sets the second predetermined time based on the total power generation time. (Step S13). Then, the CPU 148 performs a purge process. That is, after the aqueous solution pump 132 is stopped, the air pump 134 is driven for the set second predetermined time (step S15), and the process ends.

  According to the fuel cell system 100 operating in this way, every time the power generation time of the cell stack 102 elapses for the first predetermined time (here, 1 hour), the output power of the cell stack 102 is considered to decrease, and the air pump The air supply amount by 134 is increased by a predetermined amount (here, 5%). As a result, the amount of air supplied by the air pump 134 can be set to a small value for a while from the start of power generation of the cell stack 102, and then gradually increased periodically, and the control can be simplified. Accordingly, the saturated vapor pressure in the cathode 110 of the cell stack 102 can be gradually increased to promote the vaporization of the liquid in the cathode 110 and the discharge of the liquid from the cathode 110 can be promoted, and gradually proceeds with time. The progress of flooding of the cell stack 102 having the property can be suppressed. As a result, while preventing waste of electric power due to a sudden increase in the amount of air supplied by the air pump 134, a decrease in the output power of the cell stack 102 and the fuel cell 104 can be suppressed, and a decrease in power generation efficiency can be suppressed.

  In addition, after setting the second predetermined time according to the amount of liquid present in the cathode 110 based on the total power generation time of the cell stack 102 and stopping the power generation of the cell stack 102, after stopping the aqueous solution pump 132 Then, the air pump 134 is driven for a second predetermined time. As a result, compared with the case where the aqueous solution pump 132 and the air pump 134 are stopped simultaneously, more liquid of the cathode 110 can be discharged at the end of power generation, and the time until flooding occurs in the next power generation is lengthened. be able to. Further, by setting the second predetermined time based on the total power generation time of the cell stack 102, it is possible to prevent waste of power required for driving the air pump 134.

The effect of performing the operation of FIG. 4 will be described with reference to FIG.
FIG. 6A shows an example of the gross output power of the cell stack when the power generation and the stop of the cell stack are performed three times in the conventional example. FIG. 6B shows, as data corresponding to one of them, the gross output power and net output power of the cell stack and the auxiliary machine power consumption when the operation of FIG. 4 is performed and in the conventional example. The net output power of the cell stack is the gross output power of the cell stack minus the auxiliary machine power consumption.

  As shown in FIG. 6A, the output power of the cell stack rises rapidly after the start of power generation, and then gradually decreases with time.

  Referring to FIG. 6B, in the conventional example, the power consumption of the auxiliary machine (including the air pump) is constant as shown by the broken line A1, but the gross output power of the cell stack is the time as shown by the broken line A2. Therefore, the net output power of the cell stack also decreases with time as shown by the broken line A3.

  On the other hand, when the fuel cell system 100 performs the operation of FIG. 4, the power consumption of the auxiliary machine (including the air pump 134) is equal to the amount of air supplied by the air pump 134 every time the first predetermined time elapses as shown by the solid line B1. It increases with the increase. As shown by the solid line B2, the gross output power of the cell stack 102 gradually decreases, then increases sharply as the air supply amount by the air pump 134 increases (rises directly above), and repeats that. And the time to flooding becomes longer. Along with this, the net output power of the cell stack 102 also has a saw-tooth characteristic as shown by the broken line B3, and can suppress a decrease compared to the conventional example.

Next, another operation example of the fuel cell system 100 will be described with reference to FIG.
In the operation example shown in FIG. 7, the processes of steps S3a and S3b are performed instead of the process of step S3 of the operation example shown in FIG. 4, and the process of step S11a is performed instead of the process of step S11. Since other operations are the same as the operation of FIG. 4, the same step numbers are assigned, and redundant description is omitted.

  In the operation example shown in FIG. 7, in step S3a after step S1, the CPU 148 continuously acquires and averages the output power after 5 minutes from the start of power generation for 2 minutes. This average value is used as the output power initial value. In step S3b, the CPU 148 determines whether or not the gross output power of the cell stack 102 has decreased by a predetermined amount (here, 5% or more) from the output power initial value. If the gross output power has not decreased by a predetermined amount, the process proceeds to step S5, and if it has decreased by a predetermined amount, the process proceeds to step S9.

  In addition, after step S9, the CPU 148 clears the initial output power value obtained in step S3a, and returns to step S1.

  According to the fuel cell system 100 operating in this manner, the output power of the cell stack 102 is detected, and the air supply amount by the air pump 134 is reduced by a predetermined amount (here, every time the value is reduced by a predetermined amount (here, 5%)). 5%) increase. As a result, the amount of air supplied by the air pump 134 can be accurately controlled, and a decrease in the output power of the cell stack 102 can be more reliably suppressed. In addition, the same effect as when performing the operation of FIG. 4 can be obtained.

The effect of performing the operation shown in FIG. 7 will be described with reference to FIG.
FIG. 8A is the same diagram as FIG. 6A, and FIG. 8A shows the gross output power of the cell stack when the power generation and the stop of the cell stack are performed three times in the conventional example. An example is shown. FIG. 8B shows, as data corresponding to one of them, the gross output power and net output power of the cell stack and auxiliary device power consumption in the case where the operation of FIG. 7 is performed and in the conventional example. The broken lines A1 to A3 in FIG. 8B are the same conventional examples as the broken lines A1 to A3 in FIG.

  Referring to FIG. 8B, when the fuel cell system 100 performs the operation of FIG. 7, the power consumption of the auxiliary machine (including the air pump 134) is calculated every time the gross output power of the cell stack 102 decreases by a predetermined amount. As the air supply amount by the air pump 134 increases, it increases as shown by the solid line C1. As shown by the solid line C2, the gross output power of the cell stack 102 gradually decreases, then increases sharply as the air supply amount by the air pump 134 increases (rises right above), and repeats that. And the time to flooding becomes longer. Along with this, the net output power of the cell stack 102 also has a sawtooth characteristic as shown by the solid line C3, and can suppress the decrease compared to the conventional example shown by the broken line A3.

  In the operation example shown in FIG. 7, it is determined in step S3b whether or not the gross output power of the cell stack 102 has decreased by a predetermined percentage (here, 5%) from the output power initial value. However, the present invention is not limited to this. . For example, it may be determined whether the gross output power of the cell stack 102 has decreased by a predetermined amount from the initial output power value.

  In the above-described embodiment, the output power of the cell stack 102 is used as information on the output power of the fuel cell 104. However, the present invention is not limited to this, and the output power of the fuel cell 104 may be used. The output power of the fuel cell 104 is obtained by dividing the output power of the cell stack 102 by the number of fuel cells 104 included in the cell stack 102. Further, as the information related to the output power of the fuel cell 104, the output voltage and output current of the fuel cell 104 and the output voltage and output current of the cell stack 102 may be used.

  In the above embodiment, methanol is used as the fuel, and methanol aqueous solution is used as the fuel aqueous solution. However, the present invention is not limited to this, and alcohol-based fuel such as ethanol may be used as the fuel, and alcohol-based aqueous solution such as ethanol aqueous solution may be used as the fuel aqueous solution. Good.

  In the above-described embodiment, the case where air is supplied to the cathode 110 of the cell stack 102 (fuel cell 104) by the air pump 134 has been described, but the present invention is not limited to this. In the present invention, any gas containing an oxidant can be supplied to the cathode 110, and any air supply pump can be used as the gas supply unit.

  Since transportation equipment such as the motorcycle 10 is easily subjected to vibration or the like due to external force during operation, flooding is likely to occur when the fuel cell system is mounted on the transportation equipment. According to the present invention, since the occurrence of flooding can be suppressed and the decrease in power generation efficiency can be suppressed, the present invention is suitably used for any transportation equipment including a fuel cell system. The transportation equipment includes not only motorcycles but also automobiles and ships.

  The present invention can also be applied to a stationary fuel cell system, and can also be applied to a portable fuel cell system mounted on an electronic device such as a personal computer or a portable device.

DESCRIPTION OF SYMBOLS 10 Motorcycle 38 Electric motor 100 Fuel cell system 102 Fuel cell cell stack 104 Fuel cell 108 Anode 110 Cathode 132 Aqueous solution pump 134 Air pump 136 Controller 148 CPU
150 Clock circuit 152 Memory 154 Voltage detection circuit 156 Current detection circuit

Claims (6)

A fuel cell having an anode and a cathode;
A gas supply unit for supplying a gas containing an oxidant to the cathode of the fuel cell;
An information acquisition unit for acquiring correlation information correlated with the output power of the fuel cell;
A control unit that controls a gas supply amount by the gas supply unit based on the correlation information acquired by the information acquisition unit;
The control unit increases the gas supply amount by the gas supply unit every time the correlation information indicates a decrease in the output power of the fuel cell. The correlation information includes the power generation time of the fuel cell,
2. The fuel cell system according to claim 1, wherein the control unit increases a gas supply amount by the gas supply unit every time the power generation time passes a first predetermined time. The correlation information includes information related to output power of the fuel cell,
2. The fuel cell system according to claim 1, wherein the control unit increases a gas supply amount by the gas supply unit every time information on the output power of the fuel cell decreases by a predetermined amount. An aqueous solution supply unit for supplying an aqueous fuel solution to the anode of the fuel cell;
2. The fuel cell system according to claim 1, wherein when the power generation of the fuel cell is stopped, the control unit drives the gas supply unit for a second predetermined time after stopping the aqueous solution supply unit. A time acquisition unit for acquiring a total power generation time from the start of power generation of the fuel cell;
The fuel cell system according to claim 4, wherein the control unit sets the second predetermined time based on the total power generation time acquired by the time acquisition unit. A fuel cell system according to any one of claims 1 to 5,
A transportation device comprising: an electric motor to which electric power is supplied from the fuel cell system.

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