JP2014127368A - Fuel cell system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fuel cell system suppressing an increase of hydrogen concentration of gas exhausted from the fuel cell system.SOLUTION: A fuel cell system includes: two anode off-gas exhaust passages 47, 48 for exhausting anode off-gas to the outside; and a first purge valve 49 and a second purge valve 50 provided in the anode off-gas exhaust passages 47, 48, respectively. When a cathode gas flow rate required at the case where the first purge valve 49 and the second purge valve 50 are simultaneously opened is greater than a cathode gas flow rate limit value and the cathode gas flow rate is limited, at least one of a valve opening time of the first purge valve 49 and the second purge valve 50 is limited.

Description

  The present invention relates to a fuel cell system.

  When power is generated by the fuel cell, impurities are generated in the anode of the fuel cell. Therefore, in order to maintain the hydrogen concentration, the concentration is maintained by purging impurities in the anode together with hydrogen.

  On the other hand, when purging impurities, it is known to dilute with cathode gas so that the hydrogen concentration of the exhausted gas is sufficiently low.

  The fuel cell system of Patent Document 1 includes two purge valves for discharging impurities, and both valves are repeatedly opened and closed at a predetermined cycle. One valve opens from the start of the valve opening cycle, and the other purge valve opens to coincide with the end of the valve opening cycle. The opening time of the two purge valves becomes longer in proportion to the amount of impurities (nitrogen and water) in the anode.

PCT / JP2011 / 006647

  In the above purging method, since the opening / closing cycle of both valves is determined, if the opening time of the two purge valves becomes longer, both valves will be opened simultaneously. In comparison, the amount of hydrogen discharged is approximately doubled. Therefore, on the cathode side, it is necessary to set the hydrogen concentration below a predetermined concentration by flowing more cathode gas than when only one valve is opened.

  In order to perform this dilution, the flow rate of the cathode gas by the compressor is increased. However, depending on the state of the fuel cell system, the compressor may not be able to flow the necessary flow rate of the cathode gas when the two purge valves are opened simultaneously. For example, this is a case where the flow rate of the compressor is limited for heat resistance protection of a WRD (Water Recovery Device).

  In this case, there is a possibility that the hydrogen concentration of the gas discharged together with the impurities by the purge cannot be made lower than the predetermined concentration. An object of the present invention is to provide an apparatus capable of suppressing an increase in the hydrogen concentration of a gas discharged together with impurities by purging even in such a situation.

  A fuel cell system according to an aspect of the present invention is a fuel cell system having a fuel cell stack, a cathode gas supply device for supplying cathode gas to the fuel cell stack via a cathode gas supply passage, and a cathode gas A first purge that joins the supply passage or the cathode off-gas discharge passage and is provided in two anode off-gas discharge passages through which the anode off-gas of the fuel cell stack flows and one of the anode off-gas discharge passages and discharges the anode off-gas to the outside A valve, a second purge valve that is provided in the other anode offgas discharge passage and discharges the anode offgas to the outside, and a valve opening time of the first purge valve that is determined based on the state of the fuel cell system A first purge valve control means for controlling the opening and closing of the first purge valve; A second purge valve control means for controlling the opening and closing of the second purge valve based on the opening time of the second purge valve determined based on the state of the system; In the situation where the valve is opened, the cathode flow rate control means for increasing the cathode gas flow rate by the cathode gas supply device compared to when the valve is not opened at the same time, and the cathode gas flow rate when the cathode gas flow rate is larger than the cathode gas flow rate limit value. A cathode gas flow rate limiting means for limiting. The first purge valve control means and the second purge valve control means provide at least the opening time of either the first purge valve or the second purge valve when the cathode gas flow rate is restricted by the cathode gas flow rate restriction means. Restrict.

  According to this aspect, when the first purge valve and the second purge valve are simultaneously opened, when the cathode gas flow rate is limited, at least one of the first purge valve and the second purge valve is opened. By limiting this, it is possible to suppress an increase in the hydrogen concentration of the gas discharged together with impurities from the anode of the fuel cell stack.

It is a schematic block diagram of the fuel cell system of this embodiment. It is a figure explaining opening and closing of the 1st purge valve and the 2nd purge valve. It is a control block diagram explaining a purge control part. It is a control block diagram explaining a liquid water discharge request DUTY setting unit. It is a control block diagram explaining a permeated gas discharge request DUTY setting unit. It is a control block diagram explaining a simultaneous valve opening request determination part. It is a control block diagram explaining a simultaneous valve opening prohibition flag setting unit. It is a control block diagram explaining a purge valve restriction DUTY setting unit. It is a control block diagram explaining an anode impurity gas accumulation amount setting unit. It is a control block diagram explaining a cooling control part.

  The configuration of the embodiment of the present invention will be described with reference to FIG. FIG. 1 is a schematic configuration diagram of an anode gas non-circulating fuel cell system 1.

  The fuel cell system 1 includes a fuel cell stack 2, a cathode gas supply / discharge device 3, an anode gas supply / discharge device 4, a stack cooling device 6, and a controller 7.

  The fuel cell stack 2 is formed by stacking a plurality of fuel cells, and generates electric power by receiving supply of hydrogen and cathode gas to generate electric power necessary for driving the vehicle (for example, electric power necessary for driving a motor). Generate electricity.

  The cathode gas supply / discharge device 3 includes a cathode gas supply passage 31, a filter 32, an air compressor 33, an air flow sensor 34, a cathode gas discharge passage 35, a bypass passage 36, a flow control valve 37, and a pressure sensor 38. And an air pressure control valve 39.

  The cathode gas supply passage 31 is a passage through which the cathode gas supplied to the cathode side of the fuel cell stack 2 flows. The cathode gas supply passage 31 has one end connected to the filter 32 and the other end connected to the cathode gas inlet hole 21 of the fuel cell stack 2. The cathode gas supply passage 31 may be provided with a WRD for humidifying the cathode gas.

  The filter 32 removes foreign matters in the cathode gas taken into the cathode gas supply passage 31.

  The air compressor 33 is provided in the cathode gas supply passage 31. The air compressor 33 takes air (outside air) as cathode gas through the filter 32 into the cathode gas supply passage 31 and supplies it to the fuel cell stack 2.

  The air flow sensor 34 is provided in the cathode gas supply passage 31 upstream of the air compressor 33. The air flow sensor 34 detects the flow rate of the cathode gas flowing through the cathode gas supply passage 31.

  The cathode gas discharge passage 35 is a passage through which the cathode off-gas discharged from the fuel cell stack 2 and the cathode gas supplied from the cathode gas supply passage 31 via the bypass passage 36 flow. One end of the cathode gas discharge passage 35 is connected to the cathode gas outlet hole 22 of the fuel cell stack 2 and the other end is an open end.

  The bypass passage 36 bypasses the fuel cell stack 2 and connects the cathode gas supply passage 31 and the cathode gas discharge passage 35. The bypass passage 36 can supply the cathode gas to the cathode gas discharge passage 35 by bypassing the fuel cell stack 2 from the cathode gas supply passage 31.

  The flow control valve 37 is provided in the bypass passage 36. The flow control valve 37 is an electromagnetic valve whose opening degree can be adjusted continuously or stepwise, and the opening degree is controlled by the controller 7. Even when the flow rate of the cathode gas required in the fuel cell stack 2 is small by opening the flow rate control valve 37, the cathode gas required for diluting the anode off gas described later is supplied to the cathode gas discharge passage via the bypass passage 36. 35.

  The pressure sensor 38 is provided in the cathode gas supply passage 31 on the downstream side (fuel cell stack 2 side) from the location where the bypass passage 36 is connected. The pressure sensor 38 detects the pressure in the cathode gas supply passage 31 supplied to the fuel cell stack 2. In the present embodiment, the pressure detected by the pressure sensor 38 is used as the pressure of the entire cathode system of the fuel cell stack 2.

  The air pressure control valve 39 is provided upstream of the junction portion of the bypass passage 36 in the cathode gas discharge passage 35. The air pressure control valve 39 is an electromagnetic valve whose opening degree can be adjusted continuously or stepwise. The opening degree is controlled by the controller 7, and the air pressure control valve 39 is made smaller by reducing the opening degree of the air pressure control valve 39. The cathode pressure of the battery stack 2 can be increased.

  The anode gas supply / discharge device 4 includes a high pressure tank 41, an anode gas supply passage 42, a pressure regulating valve 43, a pressure sensor 44, a first anode gas discharge passage 45, a second anode gas discharge passage 46, a first A purge passage 47, a second purge passage 48, a first purge valve 49, a second purge valve 50, and a buffer tank 51 are provided.

  The high pressure tank 41 stores the hydrogen supplied to the fuel cell stack 2 while maintaining the high pressure state.

  The anode gas supply passage 42 is a passage for supplying hydrogen discharged from the high-pressure tank 41 to the anode side of the fuel cell stack 2, one end of which is connected to the high-pressure tank 41 and the other end of the fuel cell stack. 2 anode gas inlet holes 23.

  The pressure regulating valve 43 is provided in the anode gas supply passage 42. The pressure regulating valve 43 adjusts the hydrogen discharged from the high-pressure tank 41 to a desired pressure and supplies it to the fuel cell stack 2. The pressure regulating valve 43 is an electromagnetic valve whose opening degree can be adjusted continuously or stepwise, and the opening degree is controlled by the controller 7.

  The pressure sensor 44 is provided in the anode gas supply passage 42 downstream of the pressure regulating valve 43. The pressure sensor 44 detects the pressure in the anode gas supply passage 42 downstream from the pressure regulating valve 43. In the present embodiment, the pressure detected by the pressure sensor 44 is used as the pressure of the entire anode system of the fuel cell stack 2 including the buffer tank 51.

  The first anode gas discharge passage 45 has one end connected to the first anode gas outlet hole 24 of the fuel cell stack 2 and the other end connected to the buffer tank 51. In the first anode gas discharge passage 45, surplus anode gas that has not been used for the electrode reaction of the fuel cell stack 2 and inert gas such as cathode gas (such as nitrogen) or water vapor that has permeated from the cathode side to the anode side. A mixed gas with the gas (hereinafter referred to as “anode off gas”) and generated water (hereinafter referred to as “liquid water”) generated by the electrode reaction of the fuel cell stack 2 are discharged.

  The second anode gas discharge passage 46 has one end connected to the second anode gas outlet hole 25 of the fuel cell stack 2 and the other end connected to the buffer tank 51. Anode off gas and liquid water are discharged into the second anode gas discharge passage 46.

  The first purge passage 47 has one end connected to the first anode gas discharge passage 45 and the other end connected to the cathode gas discharge passage 35 downstream of the air pressure control valve 39.

  The second purge passage 48 has one end connected to the second anode gas discharge passage 46 and the other end connected to the cathode gas discharge passage 35 downstream of the air pressure control valve 39.

  The first purge valve 49 is provided in the first purge passage 47. The first purge valve 49 is an electromagnetic valve capable of adjusting the opening degree to be fully open or fully closed, and is controlled by the controller 7.

  The second purge valve 50 is provided in the second purge passage 48. The second purge valve 50 is an electromagnetic valve whose opening degree can be adjusted to fully open or fully closed, and is controlled by the controller 7.

  By opening and closing the first purge valve 49 and the second purge valve 50, the amount of anode offgas and liquid water discharged from the buffer tank 51 to the outside air via the purge passages 47 and 48 is adjusted, and the inside of the buffer tank 51 At the same time as adjusting the hydrogen concentration to a desired concentration, liquid water is prevented from accumulating in the anode. If the hydrogen concentration in the buffer tank 51 is too low, the hydrogen used for the electrode reaction when generating power in the fuel cell stack 2 using the hydrogen in the buffer tank 51 is insufficient, resulting in power generation failure and the fuel cell. May deteriorate. On the other hand, if the hydrogen concentration in the buffer tank 51 is too high, the amount of hydrogen discharged to the outside air together with the inert gas in the anode off-gas via the purge passages 47 and 48 increases, resulting in a deterioration in fuel consumption. Therefore, the hydrogen concentration in the buffer tank 51 is controlled to an appropriate value in consideration of power generation efficiency and fuel consumption. In addition, when the amount of liquid water in the anode increases, the supply of hydrogen to the MEA at the anode is hindered, and power generation failure may occur in the fuel cell stack 2. Accordingly, the liquid water in the anode is appropriately discharged.

  The buffer tank 51 temporarily stores the anode off gas flowing through the first anode gas discharge passage 45 and the second anode gas discharge passage 46. The anode off gas stored in the buffer tank 51 is discharged to the cathode gas discharge passage 35 through the first purge passage 47 or the second purge passage 48 when the first purge valve 49 or the second purge valve 50 is opened. Is done. As a result, a mixed gas of anode off-gas, cathode off-gas and cathode gas (hereinafter referred to as “outside air exhaust gas”) is discharged from the open end of the cathode gas discharge passage 35 to the outside air. In this way, the anode off gas is mixed with the cathode off gas and the cathode gas and then discharged to the outside air, so that the hydrogen concentration in the outside air exhaust gas becomes less than a predetermined combustible concentration. The anode off gas in the buffer tank 51 flows into the fuel cell stack 2 when the pressure of hydrogen supplied from the pressure regulating valve 43 decreases, and the hydrogen in the anode off gas is used for the electrode reaction of the fuel cell stack 2. In the following description, the cathode off gas and the cathode gas forming the outside air exhaust gas are simply referred to as the cathode off gas.

  The stack cooling device 6 is a device that cools the fuel cell stack 2 and maintains the fuel cell stack 2 at a temperature suitable for power generation. The stack cooling device 6 includes a cooling water circulation passage 61, a radiator 62, a bypass passage 63, a three-way valve 64, a circulation pump 65, an electric heater 66, a first water temperature sensor 69, a second water temperature sensor 80, And a radiator fan 81.

  The cooling water circulation passage 61 is a passage through which cooling water for cooling the fuel cell stack 2 circulates, and one end is connected to the cooling water inlet hole 26 of the fuel cell stack 2 and the other end is cooling the fuel cell stack 2. Connected to the water outlet hole 27.

  The radiator 62 is provided in the cooling water circulation passage 61. The radiator 62 is discharged from the fuel cell stack 2 and exchanges heat between the cooling water flowing inside the radiator 62 and the air flowing outside the radiator 62 by the radiator fan 81 or the like, thereby cooling the cooling water.

  The rotation speed of the radiator fan 81 is controlled by the controller 7 to adjust the flow rate of air flowing outside the radiator 62.

  One end of the bypass passage 63 is connected to the cooling water circulation passage 61 between the cooling water outlet hole 27 of the fuel cell stack 2 and the radiator 62 so that the cooling water can be circulated by bypassing the radiator 62. The end is connected to the three-way valve 64.

  The three-way valve 64 is provided in the cooling water circulation passage 61 on the downstream side between the radiator 62 and the cooling water inlet hole 26 of the fuel cell stack 2. The three-way valve 64 switches the cooling water circulation path according to the temperature of the cooling water. Specifically, when the temperature of the cooling water is relatively high, the cooling water circulation path is such that the cooling water discharged from the fuel cell stack 2 is supplied again to the fuel cell stack 2 via the radiator 62. Switch. On the other hand, when the temperature of the cooling water is relatively low, the cooling water discharged from the fuel cell stack 2 flows through the bypass passage 63 without passing through the radiator 62 and is supplied to the fuel cell stack 2 again. Switch the cooling water circulation path.

  The circulation pump 65 is provided in the cooling water circulation passage 61 on the downstream side of the three-way valve 64 and circulates the cooling water.

  The electric heater 66 is provided in the bypass passage 63. The electric heater 66 is energized when the fuel cell stack 2 is warmed up, etc., and raises the temperature of the cooling water.

  The first water temperature sensor 69 is provided in the cooling water circulation passage 61 in the vicinity of the cooling water outlet hole 27 of the fuel cell stack 2. The first water temperature sensor 69 detects the temperature of the cooling water discharged from the fuel cell stack 2.

  The second water temperature sensor 80 is provided in the cooling water circulation passage 61 in the vicinity of the cooling water inlet hole 26 of the fuel cell stack 2. The second water temperature sensor 80 detects the temperature of the cooling water supplied to the fuel cell stack 2.

  The controller 7 includes a microcomputer having a central processing unit (CPU), a read only memory (ROM), a random access memory (RAM), and an input / output interface (I / O interface).

  In addition to the air flow sensor 34, the pressure sensors 44 and 38, the first water temperature sensor 69, the second water temperature sensor 80, and the third water temperature sensor 71, the controller 7 includes a current for detecting the output current of the fuel cell stack 2. The operating state of the fuel cell system 1 such as a voltage sensor 73 for detecting the output voltage of the sensor 72 or the fuel cell stack 2, an accelerator stroke sensor 74 for detecting the depression amount of the accelerator pedal, and an atmospheric pressure sensor 75 for detecting atmospheric pressure is detected. Signals from various sensors are input.

  Based on these input signals, the controller 7 controls an inverter (not shown) provided between the external load and the fuel cell stack 2 according to a required load such as an external load (not shown), thereby generating power from the fuel cell stack 2 Control power. Further, the controller 7 performs a pulsation operation that periodically opens and closes the pressure regulating valve 43 based on these input signals to periodically increase and decrease the anode pressure. Further, the controller 7 opens and closes the first purge valve 49 and the second purge valve 50 to adjust the flow rate of the anode off-gas discharged from the buffer tank 51 to the outside, so that the nitrogen and liquid water into the anode of the fuel cell stack 2 are adjusted. Prevent the accumulation of.

  The opening and closing of the first purge valve 49 and the second purge valve 50 are executed at a predetermined cycle as shown in FIG. The first purge valve 49 is controlled to start to open from the beginning of a predetermined cycle when the opening time is set, and the second purge valve 50 is controlled to finish opening at the end of the predetermined cycle when the opening time is set. . When the opening time of the first purge valve 49 or the opening time of the second purge valve 50 becomes longer, simultaneous opening of the first purge valve 49 and the second purge valve 50 occurs simultaneously.

  Next, the purge valve control unit 100 for controlling the first purge valve 49 and the second purge valve 50 in the present embodiment will be described with reference to the control block diagram of FIG. The control described below is executed by the controller 7.

  The purge valve control unit 100 includes a liquid water discharge request DUTY setting unit 110, a permeate gas discharge request DUTY setting unit 120, a simultaneous valve opening request determination unit 130, a simultaneous valve opening prohibition flag setting unit 140, and a purge valve restriction DUTY. The setting unit 150 includes an anode impurity gas accumulation amount setting unit 160.

  The liquid water discharge request DUTY setting unit 110 will be described with reference to the control block diagram of FIG.

  The liquid water discharge request DUTY setting unit 110 includes an anode liquid water amount calculation unit 111, a deviation calculation unit 112, a liquid water discharge amount calculation unit 113, and a liquid water discharge request DUTY calculation unit 114.

  The anolyte water amount calculation unit 111 calculates the anolyte water amount from a preset map based on the required current and HFR (High Frequency Resistance). HFR is calculated by a known AC impedance method. It is known that the internal resistance of the fuel cell stack 2 varies depending on the wet state of the electrolyte membrane of the fuel cell stack 2. Therefore, the wet state of the electrolyte membrane of the fuel cell stack 2 can be indirectly detected by detecting the HFR of the fuel cell stack 2. An increase in HFR means that the electrolyte membrane is dry. The HFR is calculated using, for example, a method described in Japanese Patent Application Laid-Open No. 2012-054153 filed by the present applicant. The amount of anolyte water increases as the required current increases, and increases as the HFR decreases and the electrolyte membrane gets wet.

  The deviation calculation unit 112 calculates a deviation between the target anode pressure and the atmospheric pressure. The target anode pressure is calculated according to the required current.

  The liquid water discharge amount calculation unit 113 calculates a liquid water dischargeable amount based on the deviation calculated by the deviation calculation unit 112 from a preset table. The amount of liquid water that can be discharged increases as the deviation increases.

  The liquid water discharge request DUTY calculation unit 114 calculates the liquid water discharge request DUTY by dividing the anode liquid water amount by the liquid water discharge amount.

  Thus, the liquid water discharge request DUTY setting unit 110 sets the liquid water discharge request DUTY based on the state of the fuel cell system 1.

  The permeated gas discharge request DUTY setting unit 120 will be described with reference to the control block diagram of FIG.

  The permeated gas discharge request DUTY setting unit 120 includes a cathode gas permeation amount calculation unit 121, an anode impurity gas dischargeable amount calculation unit 122, a permeate gas discharge request DUTY calculation unit 123, a permeate gas discharge request DUTY correction unit 124, The first purge valve DUTY selection unit 125 is configured.

  The cathode gas permeation amount calculation unit 121 calculates a cathode gas permeation amount permeating from the cathode side to the anode side based on the cathode pressure detected by the pressure sensor 38 and the fuel cell temperature from a preset map. The fuel cell temperature is an average value of the temperature detected by the first water temperature sensor 69 and the temperature detected by the second water temperature sensor 80. The cathode gas permeation amount increases as the cathode pressure increases and increases as the fuel cell temperature increases. The cathode gas permeation amount is the permeation amount of the cathode gas permeating from the cathode side to the anode side per unit time.

  The anode impurity gas dischargeable amount calculation unit 122 calculates an anode impurity gas dischargeable amount from a preset map based on the target anode pressure and the atmospheric pressure detected by the atmospheric pressure sensor 75. The amount of anode impurity gas that can be discharged increases as the target anode pressure increases and increases as the atmospheric pressure decreases. The anode impurity off-gas dischargeable amount is the discharge amount of anode impurity gas that can be discharged from the anode per unit time.

  The permeate gas discharge request DUTY calculation unit 123 calculates the permeate gas discharge request DUTY by dividing the cathode gas permeation amount by the anode impurity gas dischargeable amount.

  The permeate gas discharge request DUTY correction unit 124 calculates a permeate gas discharge request correction DUTY by adding a predetermined DUTY to the permeate gas discharge request DUTY when an anode impurity gas accumulation amount described later in detail is not zero. The predetermined DUTY is a preset DUTY, for example, 2 is set. If the anode impurity gas is accumulated in the anode, it accumulates in the anode by adding a predetermined DUTY to the DUTY calculated by the permeate gas discharge request DUTY 123 and extending the opening time of the first purge valve 49. The anode impurity gas is discharged to the outside. The permeate gas discharge request DUTY correction unit 124 calculates the permeate gas discharge request DUTY as the permeate gas discharge request correction DUTY when the anode impurity gas accumulation amount is zero. The predetermined DUTY may be set in accordance with the anode impurity gas accumulation amount. In this case, the predetermined DUTY increases as the anode impurity gas accumulation amount increases.

  The first purge valve DUTY selection unit 125 compares the permeated gas discharge request correction DUTY with the liquid water discharge request DUTY, and selects the larger DUTY as the first purge valve DUTY. Here, the permeated gas discharge request correction DUTY and the liquid water discharge request DUTY are compared, for example, whether the liquid water is discharged from the first purge valve 49 or the second purge valve 50 depending on the inclination of the vehicle. This is because. In the present embodiment, when the liquid water discharge request DUTY, which is DUTY for discharging liquid water, is larger than the permeated gas discharge request correction DUTY, which is DUTY for discharging the cathode gas that has permeated to the anode, The 1 purge valve DUTY selection unit 125 selects the liquid water discharge request DUTY as the first purge valve DUTY in order to reliably discharge the liquid water. When the permeate gas discharge request correction DUTY is larger than the liquid water discharge request DUTY, the first purge valve 49 is discharged through the permeate gas in order to discharge the anode off-gas even when the liquid water is on the first purge valve 49 side. When opening based on the request correction DUTY, the liquid water discharge amount calculated by the liquid water discharge amount calculation unit 113 is discharged from the first purge valve 49 together with the anode off gas.

  As described above, the permeate gas discharge request DUTY setting unit 120 sets the first purge valve DUTY based on the state of the fuel cell system 1.

  The simultaneous valve opening request determination unit 130 will be described with reference to the control block diagram of FIG.

  The simultaneous valve opening request determination unit 130 includes a total DUTY calculation unit 131 and a simultaneous valve opening determination flag selection unit 132.

  The total DUTY calculating unit 131 calculates the total DUTY by adding the first purge valve DUTY and the liquid water discharge request DUTY. In the present embodiment, the predetermined cycle in which the opening and closing of the first purge valve 49 and the second purge valve 50 are repeated corresponds to the case where the total DUTY is 1. That is, when the total DUTY is 1, the second purge valve 50 is opened at the same time as the first purge valve 49 is closed during a predetermined period. If the total DUTY is greater than 1, the first purge valve 49 and the second purge valve 50 are opened and closed based on the first purge valve DUTY and the liquid water discharge request DUTY, and the first DUTY is output during a predetermined period. Simultaneous opening of the purge valve 49 and the second purge valve 50 is generated.

  When the total DUTY is greater than 1, the simultaneous valve opening determination flag selection unit 132 opens and closes the first purge valve 49 and the second purge valve 50 based on the first purge valve DUTY and the liquid water discharge request DUTY. Since simultaneous opening occurs, “1” is selected as the simultaneous opening determination flag. On the other hand, when the total DUTY is smaller than 1, the simultaneous valve opening determination flag selection unit 132 sets the first purge valve 49 and the second purge valve 50 based on the first purge valve DUTY and the liquid water discharge request DUTY. Even if the valve is opened and closed, simultaneous valve opening does not occur during a predetermined period, so “0” is selected as the simultaneous valve opening determination flag.

  The simultaneous valve opening prohibition flag setting unit 140 will be described with reference to the control block diagram of FIG.

  The simultaneous valve opening prohibition flag setting unit 140 includes a power generation request cathode gas flow rate calculation unit 141, a dilution cathode gas flow rate calculation unit 142, a dilution coefficient selection unit 143, a final dilution cathode gas flow rate calculation unit 144, and a required cathode gas flow rate. The selector 145, the cathode gas flow rate restriction unit 146, the target cathode gas flow rate selection unit 147, the target air compressor flow rate selection unit 148, and the simultaneous valve opening prohibition flag selection unit 149 are configured.

  The power generation required cathode gas flow rate calculation unit 141 calculates the power generation required cathode gas flow rate based on the required current from a preset map. As the required current increases, the power generation required cathode gas flow rate increases. The power generation required cathode gas flow rate is a cathode gas flow rate required for the electrode reaction by the fuel cell stack 2.

  The diluted cathode gas flow rate calculation unit 142 sets the first purge valve 49 and the second purge valve 50 based on the anode pressure detected by the pressure sensor 44 and the atmospheric pressure detected by the atmospheric pressure sensor 75 from a preset map. The diluted cathode gas flow rate required to dilute the anode off gas discharged when it is opened is calculated. The diluted cathode gas flow rate is a diluted cathode gas flow rate when the first purge valve 49 and the second purge valve 50 are not opened simultaneously. The diluted cathode gas flow rate increases as the anode pressure increases and increases as the atmospheric pressure decreases.

  The dilution factor selection unit 143 selects a dilution factor based on the simultaneous valve opening determination flag. The simultaneous valve opening determination flag becomes “1” when the first purge valve 49 and the second purge valve 50 need to be simultaneously opened, and becomes “0” when it is not necessary to simultaneously open the valves. When the simultaneous valve opening determination flag is “0”, the dilution coefficient selection unit 143 selects “1” as the dilution coefficient because it is not necessary to open the first purge valve 49 and the second purge valve 50 simultaneously. When the simultaneous valve opening determination flag is “1”, it is necessary to open the first purge valve 49 and the second purge valve 50 simultaneously, so “2” is selected as the dilution coefficient.

  The final diluted cathode gas flow rate calculation unit 144 calculates the final diluted cathode gas flow rate by multiplying the diluted cathode gas flow rate by the dilution coefficient. When the simultaneous valve opening determination flag is “1”, that is, when it is necessary to open the first purge valve 49 and the second purge valve 50 simultaneously, the dilution coefficient is “2” and the first purge is performed. The final diluted cathode gas flow rate when the valve 49 and the second purge valve 50 need to be opened simultaneously is the final diluted cathode gas flow rate when the first purge valve 49 and the second purge valve 50 do not need to be opened simultaneously. The flow rate is twice the flow rate.

  The required cathode gas flow rate selection unit 145 compares the power generation required cathode gas flow rate with the final diluted cathode gas flow rate, and selects the larger flow rate as the required cathode gas flow rate.

  The cathode gas flow rate restriction unit 146 calculates the cathode gas restriction flow rate based on the restriction state of the air compressor 33 from a preset map. For example, when the temperature of the intake cathode gas is high, the flow rate of the air compressor 33 is limited due to the heat resistance of the air compressor 33 itself or the heat resistance of components downstream from the air compressor 33. There is. Therefore, the cathode gas flow rate restriction unit 146 calculates the cathode gas restriction flow rate that can be supplied by the air compressor 33 from the restriction state of the air compressor 33. The restricted state of the air compressor 33 is determined by, for example, the temperature of the cathode gas, the temperature of the air compressor 33, and the like. For example, the restriction state increases as the temperature of the cathode gas increases. When the restriction state of the air compressor 33 increases, the cathode gas restriction flow rate decreases.

  The target cathode gas flow rate selection unit 147 compares the required cathode gas flow rate with the cathode gas limit flow rate, and selects the smaller flow rate as the target cathode gas flow rate. When the required cathode gas flow rate is greater than the cathode gas limit flow rate, the target cathode gas flow rate selection unit 147 selects the cathode gas limit flow rate as the target cathode gas flow rate in order to limit the cathode gas flow rate. For example, even when the simultaneous valve opening determination flag is “1” and the first purge valve 49 and the second purge valve 50 need to be simultaneously opened, the required cathode gas flow rate is higher than the cathode gas limit flow rate. When there are many, the target cathode gas flow rate selection unit 147 selects the cathode gas limit flow rate as the target cathode gas flow rate in order to limit the cathode gas flow rate according to the restriction state of the air compressor 33.

  The target air compressor flow rate selection unit 148 compares the target cathode gas flow rate with the diluted cathode gas flow rate, and selects the larger flow rate as the target air compressor flow rate. Even when the target cathode gas flow rate selection unit 147 selects the cathode gas limit flow rate as the target cathode gas flow rate, the first purge valve 49 or the second purge valve 49 and the second purge valve 50 are not opened simultaneously. The anode off gas must be diluted with the cathode off gas so that the hydrogen concentration in the anode off gas discharged from the purge valve 50 is less than a predetermined combustible concentration. Therefore, when the target cathode gas flow rate is smaller than the diluted cathode gas flow rate, the target air compressor flow rate selection unit 148 selects the diluted cathode gas flow rate as the target air compressor flow rate. The air compressor 33 is controlled based on the target air compressor flow rate selected by the target air compressor flow rate selection unit 148.

  The simultaneous valve opening prohibition flag selection unit 149 compares the target air compressor flow rate with the final diluted cathode gas flow rate. When the target air compressor flow rate is smaller than the final diluted cathode gas flow rate, if the first purge valve 49 and the second purge valve 50 are simultaneously opened, the first purge valve 49 and the second purge valve 50 are discharged. Since there is a possibility that the anode off gas cannot be sufficiently diluted with the cathode off gas, the simultaneous valve opening prohibition flag selection unit 149 simultaneously opens the first purge valve 49 and the second purge valve 50 in order to prohibit simultaneous opening. “1” is selected as the prohibition flag. On the other hand, when the target air compressor flow rate is equal to or higher than the final diluted cathode gas flow rate, the anode off gas can be sufficiently diluted with the cathode off gas, so the simultaneous valve opening prohibition flag selection unit 149 uses “ Select “0”. When the simultaneous valve opening determination flag is “0” and it is not necessary to open the first purge valve 49 and the second purge valve 50 simultaneously, the final diluted cathode gas flow rate and the diluted cathode gas flow rate are equal, In the target air compressor flow rate selection unit 148, the target air compressor flow rate becomes a flow rate equal to or higher than the diluted cathode gas flow rate. Therefore, when the final diluted cathode gas flow rate and the target air compressor flow rate are compared, the target air compressor flow rate does not become smaller than the final diluted cathode gas flow rate. That is, when it is not necessary to open the first purge valve 49 and the second purge valve 50 simultaneously, the simultaneous valve opening prohibition flag does not become “1”.

  The purge valve restriction DUTY setting unit 150 will be described with reference to the control block diagram of FIG.

  The purge valve restriction DUTY setting unit 150 includes a simultaneous valve opening prohibition execution flag selecting unit 151, a final first purge valve DUTY setting unit 152, a final second purge valve DUTY setting unit 153, an adding unit 154, and a simultaneous valve opening. And an execution flag selection unit 155.

  The simultaneous valve opening prohibition execution flag selection unit 151 selects the simultaneous valve opening prohibition execution flag based on the simultaneous valve opening determination flag and the simultaneous valve opening prohibition flag. The simultaneous valve opening prohibition execution flag selection unit 151 selects “1” as the simultaneous valve opening prohibition execution flag when the simultaneous valve opening determination flag is “1” and the simultaneous valve opening prohibition flag is “1”. In other cases, “0” is selected as the simultaneous valve opening prohibition execution flag.

  The final first purge valve DUTY setting unit 152 sets the final first purge valve DUTY based on the simultaneous valve opening prohibition execution flag. The final first purge valve DUTY setting unit 152 sets the final first purge valve DUTY to 0.5 when the simultaneous valve opening prohibition execution flag is “1”. The final first purge valve DUTY setting unit 152 sets the first purge valve DUTY as the final first purge valve DUTY when the simultaneous valve opening prohibition execution flag is “0”.

  The final second purge valve DUTY setting unit 153 sets the final second purge valve DUTY based on the simultaneous valve opening prohibition flag. The final second purge valve DUTY setting unit 153 sets the final second purge valve DUTY to 0.5 when the simultaneous valve opening prohibition execution flag is “1”. The final second purge valve DUTY setting unit 153 sets the liquid water discharge request DUTY as the final second purge valve DUTY when the simultaneous valve opening prohibition execution flag is “0”.

  In this way, when the simultaneous valve opening prohibition execution flag is “1”, the purge valve restriction DUTY setting unit 150 sets the final first purge valve DUTY and the final second purge valve DUTY to 0.5, and sets the first purge valve 49 and the second purge valve 50 are prohibited from opening simultaneously.

  Based on the final first purge valve DUTY calculated by the final first purge valve DUTY setting unit 152 and the final second purge valve DUTY calculated by the final second purge valve DUTY setting unit 153, the first purge valve 49 and the second purge The valve 50 opens and closes, and the anode off gas and liquid water are discharged from the anode to the outside.

  The adding unit 154 adds the final first purge valve DUTY and the final second purge valve DUTY to calculate a final total DUTY.

  The simultaneous valve opening execution flag selection unit 155 selects a simultaneous valve opening execution flag based on the final total DUTY. The simultaneous valve opening execution flag selection unit 155 opens the first purge valve 49 and the second purge valve 50 simultaneously when the final total DUTY is greater than 1, and therefore selects “1” as the simultaneous valve opening execution flag. To do. In addition, the simultaneous valve opening execution flag selection unit 155 does not simultaneously open the first purge valve 49 and the second purge valve 50 when the final total DUTY is 1 or less, and therefore sets “0” as the simultaneous valve opening execution flag. select.

  The anode impurity gas accumulation amount setting unit 160 will be described with reference to the control block diagram of FIG.

  The anode impurity gas accumulation amount setting unit 160 includes a total DUTY calculation unit 161, an excess DUTY calculation unit 162, a deficiency DUTY setting unit 163, an anode impurity gas discharge deficiency calculation unit 164, and an anode impurity gas increase amount setting unit 165. An excess DUTY calculation unit 166, an anode impurity gas excess emission amount calculation unit 167, an anode impurity gas excess emission amount setting unit 168, an anode impurity gas increase / decrease amount calculation unit 169, and an anode impurity gas accumulation amount calculation unit 170, Consists of

  The total DUTY calculating unit 161 calculates the total DUTY by adding the first purge valve DUTY and the liquid water discharge request DUTY.

  The excess DUTY calculation unit 162 calculates a purge-unexecuted DUTY by subtracting 1 from the total DUTY calculated by the total DUTY calculation unit 161. The purge-unexecuted DUTY is a value obtained by subtracting 1 which is a total DUTY that can be realized when simultaneous opening is prohibited from the total DUTY, and is a DUTY that is insufficient when simultaneous opening is prohibited. The purge-unexecuted DUTY is a positive value when the total DUTY is larger than 1, that is, when the first purge valve 49 and the second purge valve 50 need to be opened simultaneously, and when the total DUTY is 1 or less, That is, when the first purge valve 49 and the second purge valve 50 do not need to be opened simultaneously, the value becomes zero or a negative value.

  The deficiency DUTY setting unit 163 determines whether or not the excess DUTY is a positive value, and sets the deficiency DUTY. The insufficient DUTY setting unit 163 sets the unexecuted DUTY as the insufficient DUTY when the unexecuted DUTY is a positive value. The insufficient DUTY setting unit 163 sufficiently discharges the anode off-gas in the anode without simultaneously opening the first purge valve 49 and the second purge valve 50 when the purge not executed DUTY is equal to or less than zero. Set the deficiency DUTY to zero.

  The anode impurity gas discharge insufficient amount calculation unit 164 multiplies the shortage DUTY by the anode impurity gas dischargeable amount calculated by the anode impurity gas dischargeable amount calculation unit 122 to calculate the anode impurity gas discharge insufficient amount. When the shortage DUTY is zero, the anode impurity gas discharge shortage amount is zero because the anode impurity gas can be sufficiently discharged without simultaneously opening the first purge valve 49 and the second purge valve 50.

  The anode impurity gas increase amount setting unit 165 sets the anode impurity gas increase amount at the anode according to the simultaneous valve opening prohibition execution flag. When the simultaneous valve opening prohibition execution flag is “0”, simultaneous opening of the first purge valve 49 and the second purge valve 50 is not prohibited. Therefore, even when the short DUTY is not zero, the anode impurity gas is sufficiently discharged from the anode by simultaneously opening the first purge valve 49 and the second purge valve 50, so that the anode impurity gas does not increase at the anode. . Therefore, the anode impurity gas increase amount setting unit 165 sets the anode impurity gas increase amount to zero. On the other hand, when the simultaneous valve opening prohibition execution flag is “1”, the simultaneous opening of the first purge valve 49 and the second purge valve 50 is prohibited. Therefore, when the shortage DUTY is not zero, the anode impurity gas is not sufficiently discharged from the anode, and the anode impurity gas increases at the anode. Therefore, the anode impurity gas increase amount setting unit 165 sets the anode impurity gas discharge insufficient amount as the anode impurity gas increase amount. When the anode impurity gas discharge shortage amount is zero, the anode impurity gas increase amount setting unit 165 sets the anode impurity gas increase amount to zero.

  The excess DUTY calculation unit 166 calculates the excess DUTY by subtracting the total DUTY from 2, which is DUTY when the first purge valve 49 and the second purge valve 50 are simultaneously opened.

  The anode impurity gas excessive discharge amount calculation unit 167 multiplies the excess DUTY and the anode impurity gas dischargeable amount to calculate the anode impurity gas excessive discharge amount. The excessive amount of anode impurity gas discharged is the amount of excess anode impurity gas discharged from the anode when the first purge valve 49 and the second purge valve 50 are simultaneously opened.

  The anode impurity gas surplus discharge amount setting unit 168 sets the anode impurity gas decrease amount at the anode according to the simultaneous valve opening execution flag. When the simultaneous valve opening execution flag is “0”, the first purge valve 49 and the second purge valve 50 are not simultaneously opened, so that excess anode impurity gas is not discharged from the anode. Therefore, the anode impurity gas surplus reduction amount setting unit 168 sets the anode impurity gas surplus reduction amount to zero. On the other hand, when the simultaneous valve opening execution flag is “1”, since the first purge valve 49 and the second purge valve 50 are simultaneously opened, the anode impurity gas accumulated in the anode is discharged. Therefore, the anode impurity gas surplus discharge amount setting unit 168 sets the anode impurity gas surplus discharge amount as the anode impurity gas surplus decrease amount.

  The anode impurity gas increase / decrease amount calculation unit 169 subtracts the anode impurity gas surplus decrease amount from the anode impurity gas increase amount to calculate the anode impurity gas increase / decrease amount.

  The anode impurity gas accumulation amount calculation unit 170 adds the anode impurity gas increase / decrease amount to the currently stored anode impurity gas accumulation amount to update the anode impurity gas accumulation amount. The updated amount of accumulated anode impurity gas is stored and used for the next calculation.

  As described above, if the simultaneous opening of the first purge valve 49 and the second purge valve 50 is prohibited, the inert gas in the buffer tank 51 is increased by that amount, and the hydrogen concentration is lowered and the power generation efficiency may be reduced. There is. Therefore, in the present embodiment, when simultaneous opening of the first purge valve 49 and the second purge valve 50 is prohibited, the fuel is reduced so as to reduce the influence of water vapor, which is a kind of inert gas in the buffer tank 51. The temperature of the battery stack 2 is lowered. Thereby, by reducing the water vapor contained in the buffer tank 51 and increasing the amount of impurity gas discharged from the first purge valve 49 or the second purge valve 50, the hydrogen concentration in the anode off-gas is increased, Reduces power generation efficiency.

  Next, the cooling control unit 180 for cooling the fuel cell stack 2 will be described with reference to the control block diagram of FIG. The control described below is executed by the controller 7.

  The cooling controller 180 includes a target fuel cell temperature calculator 181, a cooling system rotational speed calculator 182, a circulation pump rotational speed calculator 183, a target circulating pump rotational speed selector 184, and a radiator fan rotational speed calculator 185. And a target radiator fan rotation speed selection unit 186.

  The target fuel cell temperature calculation unit 181 calculates the target temperature of the fuel cell stack 2 based on the required current and the HFR. The target temperature is the temperature of the fuel cell stack 2 that provides the desired HFR for the required current.

  The cooling system rotation speed calculation unit 182 solves the PI controller based on the deviation between the fuel cell temperature and the target temperature so that the rotation speed of the circulation pump and the radiator fan increases as the water temperature of the fuel cell increases. Control. As described above, the fuel cell temperature is an average value of the cooling water temperature detected by the first water temperature sensor 69 and the cooling water temperature detected by the second water temperature sensor 80.

  The circulation pump rotation speed calculation unit 183 calculates the second circulation pump rotation speed from a map set in advance based on the anode impurity gas accumulation amount and the cooling water temperature detected by the second water temperature sensor 80. The rotation speed of the second circulation pump increases as the accumulated amount of anode impurity gas increases, and increases as the cooling water temperature increases.

  The target circulation pump rotation speed selection unit 184 compares the first circulation pump rotation speed and the second circulation pump rotation speed, and selects the higher rotation speed as the target circulation pump rotation speed.

  The radiator fan rotation speed calculation unit 185 calculates the second radiator from a map set in advance based on the accumulated amount of anode impurity gas in the first purge valve 49 and the second purge valve 50 and the cooling water temperature detected by the second water temperature sensor 80. Calculate the fan speed. The second radiator fan rotation speed increases as the anode impurity gas accumulation amount increases, and increases as the cooling water temperature increases.

  The target radiator fan rotation speed selection unit 186 compares the first radiator fan rotation speed and the second radiator fan rotation speed, and selects the higher rotation speed as the target radiator fan rotation speed.

  The circulation pump 65 and the radiator fan 81 are controlled based on the target circulation pump rotation speed and the target radiator fan rotation speed set in this way. Even when simultaneous opening of the first purge valve 49 and the second purge valve 50 is prohibited, the cooling water circulating through the fuel cell stack 2 is increased by increasing the rotational speed of the circulation pump 65 and the rotational speed of the radiator fan 81. Is increased, the temperature of the cooling water circulating in the fuel cell stack 2 is lowered, and the temperature of the fuel cell stack 2 is lowered. Thereby, the hydrogen concentration in the buffer tank 51 is increased by reducing the water vapor contained in the anode off-gas and increasing the inert gas discharged from the first purge valve 49 and the second purge valve 50, A decrease in power generation efficiency can be suppressed.

  The effect of the embodiment of the present invention will be described.

  When the first purge valve 49 and the second purge valve 50 are simultaneously opened, if the flow rate of the cathode off gas that can be supplied by the air compressor 33 is limited with respect to the amount of hydrogen contained in the anode off gas, the anode off gas is changed to the anode off gas. There is a possibility that the contained hydrogen cannot be sufficiently diluted.

  Therefore, in this embodiment, in such a case, the opening time of at least one of the first purge valve 49 and the second purge valve 50 is limited to restrict the first purge valve 49 and the second purge valve 50. Simultaneous valve opening is prohibited, the flow rate of the anode off-gas discharged to the outside air is reduced, and the hydrogen concentration of the outside-air exhaust gas discharged to the outside air is suppressed from increasing.

  If the simultaneous opening of the first purge valve 49 and the second purge valve 50 is prohibited, it becomes difficult to discharge the inert gas contained in the anode off-gas to be discharged, in particular nitrogen, as desired.

  Therefore, in this embodiment, in such a case, the temperature of the fuel cell stack 2 is lowered by increasing the rotation speed of the circulation pump in the circulation pump 65 and increasing the rotation speed of the radiator fan in the radiator fan 81. Since the inert gas of the anode off gas contains water vapor, the saturated water vapor pressure is lowered by lowering the temperature of the fuel cell stack 2. As a result, the water vapor present as a gas in the anode off-gas decreases, and the proportion of nitrogen in the anode off-gas increases. Therefore, even when the simultaneous opening of the first purge valve 49 and the second purge valve 50 is prohibited, a large amount of nitrogen is discharged as much as the water vapor in the anode off-gas is reduced by lowering the temperature of the fuel cell stack 2. Thus, the hydrogen concentration in the buffer tank 51 can be increased, and a reduction in the power generation efficiency of the fuel cell stack 2 can be suppressed.

  Further, water needs to be discharged from the anode of the fuel cell stack 2, but when water is present as water vapor, a sufficient purge gas flow rate is required to discharge water vapor. Therefore, in the present embodiment, when the simultaneous opening of the first purge valve 49 and the second purge valve 50 is prohibited, the temperature of the fuel cell stack 2 is lowered and the saturated steam is lowered, thereby reducing the steam. Even in a situation where the flow rate of the anode off gas that is liquefied and purged using the first purge valve 49 or the second purge valve 50 is limited, the nitrogen gas in the anode off gas can be discharged as much as possible.

  By prohibiting the simultaneous opening of the first purge valve 49 and the second purge valve 50, the nitrogen gas contained in the anode off gas is accumulated, and the ratio of the nitrogen gas in the anode off gas may increase. If this state continues for a long time, the catalyst of the fuel cell stack 2 may be deteriorated.

  In this embodiment, when the simultaneous opening of the first purge valve 49 and the second purge valve 50 is prohibited, the anode impurity gas accumulated in the anode is accumulated by prohibiting the simultaneous opening, After the prohibition of simultaneous opening of the first purge valve 49 and the second purge valve 50 is released, the opening / closing of at least the first purge valve 49 and the second purge valve 50 is controlled based on the accumulated amount of anode impurity gas. Therefore, anode impurity gas having a low hydrogen concentration accumulated in the anode can be discharged, and deterioration of the catalyst of the fuel cell stack 2 can be suppressed.

  Water that is an impurity on the anode side of the fuel cell stack 2 increases as the load on the fuel cell stack 2 increases. Therefore, it is important to discharge the increasing water from the anode of the fuel cell stack 2.

  In the present embodiment, by controlling the opening and closing of the second purge valve 50 based on the liquid water discharge request DUTY determined based on the load of the fuel cell stack 2, water generated in the fuel cell stack 2 is discharged, Flooding at the anode of the fuel cell stack 2 can be suppressed.

  Nitrogen that permeates from the cathode to the anode as an impurity of the fuel cell stack 2 increases as the pressure on the cathode side of the fuel cell stack 2 increases.

  In the present embodiment, by controlling the opening and closing of the first purge valve 49 based on the permeate waste discharge request DUTY determined based on the cathode pressure, the hydrogen concentration of the anode off-gas is suppressed, and the fuel cell A decrease in power generation efficiency of the stack 2 can be suppressed.

  The embodiment of the present invention has been described above. However, the above embodiment only shows a part of application examples of the present invention, and the technical scope of the present invention is limited to the specific configuration of the above embodiment. Absent.

  In the above embodiment, when the amount of accumulated anode impurity gas is not zero, the permeate gas discharge request DUTY correction unit 124 of the permeate gas discharge request DUTY setting unit 120 corrects the permeate gas discharge request DUTY. In other words, it is only necessary to perform correction to increase the DUTY of at least one of the first purge valve 49 and the second purge valve 50. Thus, when simultaneous opening of the first purge valve 49 and the second purge valve 50 is prohibited, the simultaneous opening is performed after the prohibition of the simultaneous opening is canceled, and the anode impurities accumulated in the anode Gas can be discharged to the outside.

  In the above embodiment, the permeate gas discharge request DUTY calculation unit 123 calculates the permeate gas discharge request DUTY by dividing the cathode gas permeation amount by the anode impurity gas dischargeable amount, and the liquid water discharge request DUTY calculation unit 114 calculates the anode liquid. Although the second purge valve DUTY is calculated by dividing the water amount by the liquid water discharge amount, the permeate gas discharge request DUTY and the liquid water discharge request DUTY may be calculated based on the divided values.

  In the above embodiment, when the simultaneous opening of the first purge valve 49 and the second purge valve 50 is restricted, the final first purge valve DUTY and the final second purge valve DUTY are restricted. You may restrict.

  In the above embodiment, the first purge passage 47 and the second purge passage 48 join the cathode gas discharge passage 35, but they may join the bypass passage 36 on the downstream side of the flow rate control valve 37.

  In the above embodiment, the second circulation pump rotation speed and the second radiator fan rotation speed are calculated based on the accumulated amount of anode impurity gas, but only one of them is calculated and either the circulation pump 65 or the radiator fan 81 is calculated. The temperature of the fuel cell stack 2 may be lowered by increasing the rotational speed of the fuel cell stack 2 alone.

2 Fuel cell stack 6 Stack cooling device (cooling means)
7 Controller (first purge valve control means, second purge valve control means, cathode gas flow rate control means, cathode gas flow rate limiting means, control means, integrating means)
33 Air compressor (cathode feeder)
47 First purge passage (anode off-gas discharge passage)
48 Second purge passage (anode off-gas discharge passage)
49 1st purge valve 50 2nd purge valve

Claims (5)

A fuel cell system having a fuel cell stack,
A cathode gas supply machine for supplying cathode gas to the fuel cell stack via the cathode gas supply passage;
Two anode offgas discharge passages that merge with the cathode gas supply passage or the cathode offgas discharge passage and through which the anode offgas of the fuel cell stack flows;
A first purge valve provided in one of the anode off gas discharge passages and discharging the anode off gas to the outside;
A second purge valve that is provided in the other anode offgas discharge passage and discharges the anode offgas to the outside;
First purge valve control means for controlling the opening and closing of the first purge valve based on the opening time of the first purge valve determined based on the state of the fuel cell system;
Second purge valve control means for controlling the opening and closing of the second purge valve based on the opening time of the second purge valve determined based on the state of the fuel cell system;
In the situation where both purge valves are opened at the same time, a cathode gas flow rate control means for increasing the cathode gas flow rate by the cathode gas supply device as compared to when not opening at the same time;
A cathode gas flow rate limiting means for limiting the cathode gas flow rate when the cathode gas flow rate is larger than a cathode gas flow rate limit value,
The first purge valve control means and the second purge valve control means are at least one of the first purge valve and the second purge valve when the cathode gas flow rate is restricted by the cathode gas flow rate restriction means. A fuel cell system that limits one valve opening time. The fuel cell system according to claim 1,
Cooling means for cooling the fuel cell stack;
Control means for controlling the cooling means based on the target temperature of the fuel cell stack,
The control unit corrects the operation amount of the cooling unit so that the temperature of the fuel cell stack is lowered when the cathode gas flow rate is limited by the cathode gas flow rate control unit. system. The fuel cell system according to claim 1 or 2,
The anode off gas that could not be discharged by limiting the anode off gas flow rate to be discharged when there is no limit when the opening time of at least one of the first purge valve and the second purge valve is limited It has a means for integrating the flow rate,
When the restriction is released, the first purge valve control means and the second purge valve control means are configured to control at least the first purge valve and the second purge valve based on the integrated anode offgas flow rate. A fuel cell system that controls either one of valve opening and valve closing. The fuel cell system according to any one of claims 1 to 3,
The second purge valve control means controls opening and closing of the second purge valve based on a valve opening time of the second purge valve determined based on a load of the fuel cell stack. A fuel cell system. A fuel cell system according to any one of claims 1 to 4,
The first purge valve control means controls opening and closing of the first purge valve based on a valve opening time of the first purge valve determined based on a pressure of the cathode of the fuel cell stack. A fuel cell system.

Images