JP2016015230A - Switch failure detection method for fuel cell system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress impairment of a solid polymer electrolyte membrane incident to close failure detection of a switch (contactor).SOLUTION: A switch failure detection method of a fuel cell includes a fuel cell for generating power by action of the fuel of an anode and the oxidizer of a cathode via a membrane, a load used by the output from the fuel cell, a switch having one end side connected to the fuel cell side and the other end side connected to the load side, and switching interruption and supply of power from the fuel cell to the load by opening and closing the contacts, and a voltage converter having primary connected to the load side of the switch, and the secondary connected to a power storage device, and capable of lowering the voltage on the primary down to a predetermined voltage capable of detecting the close failure of the switch. In the process of reducing the output from the fuel cell, the voltage converter lowers the voltage pn the primary down to the predetermined voltage, and performs close failure detection of the contacts in the switch.

Description

  The present invention relates to a switch failure detection method for a fuel cell system.

In a fuel cell of a fuel cell system mounted on a fuel cell vehicle, a solid polymer electrolyte membrane made of, for example, a solid polymer ion exchange membrane is sandwiched between an anode and a cathode from both sides, and the outside is sandwiched between a pair of separators. Some of them are made up of a stack composed of a plurality of stacked cells.
In this device, hydrogen gas as a fuel gas is supplied to the anode of each cell via a fuel supply path, and air containing oxygen as an oxidant gas is supplied to the cathode via an oxidant supply path. It is carried out.

  In the fuel cell configured as described above, hydrogen ions generated by a catalytic reaction at the anode move to the cathode through the solid polymer electrolyte membrane, and generate an electric power by causing an electrochemical reaction with oxygen at the cathode. In this type of fuel cell, it is known that the solid polymer electrolyte membrane may be deteriorated if the state in which the output voltage of the fuel cell is high while the amount of gas is small, such as in the power generation stop process.

  In addition, when this type of fuel cell system is applied to a vehicle, a configuration has been proposed in which a power storage device (energy storage) as an auxiliary power source is mounted in parallel with the fuel cell to drive a motor. This is to cover the responsiveness of the fuel cell system when the fuel cell system is variably operated according to the driving force, and to supply power to an auxiliary load such as an air pump of the fuel cell system at the time of start-up. In order to improve the efficiency of the fuel cell vehicle, the power storage device is charged with the motor regenerative energy at the time of deceleration of the vehicle, and the energy is used for assisting at the time of acceleration or the like.

  By the way, when a relatively large load is connected to the fuel cell, such as a vehicle propulsion motor, the load is provided between the fuel cell and a load to which electricity is supplied from the fuel cell. There is a risk of causing a so-called closing failure in which the movable contact and the fixed contact are welded to the switch (contactor) that connects or disconnects the contacts. There is disclosed a technique for detecting a close failure of this contactor based on a difference in voltage (or current) between both ends (fuel cell side end, load side end) of the contactor in an open state (for example, Patent Document 1). And Patent Document 2).

Japanese Patent Laid-Open No. 2-51868 JP 2007-305372 A

  According to the above prior art, a contactor closing failure is detected by a potential difference generated between both ends of an opened contactor. This potential difference is generated by maintaining the output voltage of the fuel cell. In order to suppress damage to the solid polymer electrolyte membrane, the contactor of the fuel cell system that can detect the closed failure of the contactor even when the output voltage of the fuel cell (that is, the voltage at the end of the contactor on the fuel cell side) is low A failure detection method is desired.

  The present invention has been made in view of the above circumstances, and provides a switch failure detection method for a fuel cell system capable of suppressing damage to a solid polymer electrolyte membrane accompanying detection of a close failure of a switch (contactor). The purpose is that.

  In order to solve the above-described problems and achieve the object, a switch failure detection method for a fuel cell system according to a first invention of the present invention is based on a reaction between anode fuel and cathode oxidant through a membrane. A fuel cell (for example, the fuel cell stack 11 in the embodiment), a load used by the output of the fuel cell, one end side is connected to the fuel cell side, and the other end side is connected to the load side. A switch (for example, a contactor 30 in the embodiment) that switches between cutoff and supply of electric power from the fuel cell to the load by opening and closing a contact, and the load side of the switch is connected to the primary side, and the secondary side Is connected to a power storage device, and a voltage conversion device that can step down the voltage on the primary side to a predetermined voltage that can suppress deterioration of the membrane of the fuel cell (for example, voltage adjustment in an embodiment) 40), and in the process of reducing the output of the fuel cell, the voltage conversion device steps down the primary voltage to the predetermined voltage to detect the closing failure of the contact of the switch It is characterized by doing.

  Furthermore, in the switch failure detection method for a fuel cell system according to the second aspect of the present invention, the predetermined voltage corresponds to the output voltage of the fuel cell that decreases in the process of reducing the output of the fuel cell. The voltage is stepped down.

  Furthermore, in the switch failure detection method for a fuel cell system according to the third aspect of the present invention, the process of reducing the output of the fuel cell includes a process of reducing the oxidant in the fuel cell. It is characterized by.

  According to the switch failure detection method for a fuel cell system according to the first aspect of the present invention, it is possible to suppress damage to the solid polymer electrolyte membrane that accompanies the detection of a close failure of a contactor.

  According to the switch failure detection method for a fuel cell system according to the second aspect of the present invention, the voltage at both ends of the contactor accompanying the detection of the close failure of the switch (contactor) is controlled to a value appropriate for the detection of the close failure. be able to.

  According to the switch failure detection method for a fuel cell system according to the third aspect of the present invention, the close failure detection of the switch (contactor) is detected, and the oxidant in the fuel cell that does not supply the running power from the fuel cell. It is possible to carry out simultaneously with the reduction processing process. Therefore, it is possible to reduce the influence on traveling due to the interruption of the power supply from the fuel cell by detecting the closed failure.

It is a block diagram which shows an example of a structure of the fuel cell system which concerns on embodiment of this invention. It is a flowchart which shows an example of control operation of the control apparatus which concerns on embodiment of this invention. It is a timing chart which shows an example of control operation of a control device concerning an embodiment of the present invention.

[Embodiment]
Hereinafter, a control method of a fuel cell system according to an embodiment of the present invention will be described with reference to the accompanying drawings.

FIG. 1 is a configuration diagram illustrating an example of a configuration of a fuel cell system 10 according to an embodiment of the present invention. The fuel cell system 10 according to the present embodiment is mounted as a power source in a vehicle 1 including, for example, a motor M for driving and a power drive unit PDU that controls the motor M.
The vehicle 1 includes a switch 2 that outputs a start signal for instructing the start of the vehicle 1 or a stop signal for instructing a stop in accordance with an input operation by the driver, such as an ignition switch.

  As shown in FIG. 1, the fuel cell system 10 includes a fuel cell stack 11, an air pump 13, a contactor 30, a diode 35, a current sensor 37, a voltage sensor 38, a voltage sensor 39, and a voltage regulator ( FCVCU) 40, a control device 41, a power storage device 50, and an auxiliary device 60.

The fuel cell stack 11 includes a stacked body (not shown) in which a plurality of fuel cells are stacked, and a pair of end plates (not shown) that sandwich the stacked body from both sides in the stacking direction.
The fuel cell includes a membrane electrode assembly (MEA) and a pair of separators that sandwich the membrane electrode assembly from both sides in the joining direction.
The membrane electrode assembly includes a fuel electrode (anode) composed of an anode catalyst and a gas diffusion layer, an oxygen electrode (cathode) composed of a cathode catalyst and a gas diffusion layer, and a positive electrode sandwiched from both sides in the thickness direction by the anode and the cathode. And a solid polymer electrolyte membrane made of an ion exchange membrane or the like.

A fuel gas (reaction gas) containing hydrogen as a fuel is supplied from the hydrogen tank 21 to the anode of the fuel cell stack 11, and air, which is an oxidant gas (reaction gas) containing oxygen as an oxidant, is air pumped to the cathode. 13 is supplied.
The hydrogen supplied to the anode is ionized by a catalytic reaction on the anode catalyst, and the hydrogen ions move to the cathode through a moderately humidified solid polymer electrolyte membrane. Electrons generated with the movement of hydrogen ions can be taken out to an external circuit (such as the voltage regulator 40) as a direct current.
The hydrogen ions that have moved from the anode onto the cathode catalyst of the cathode react with oxygen supplied to the cathode and electrons on the cathode catalyst to produce water.

A reference electrode (not shown) such as DHE (Dynamic Hydrogen Electrode) may be connected to the plurality of fuel cells of the fuel cell stack 11.
For example, the reference electrode can measure the potential of the anode (anode potential) with respect to the reference potential with hydrogen as the reference potential (0 V), and can output a measurement result signal to the control device 41.
For example, the reference electrode may be provided in all of the plurality of fuel cells, or may be provided only in a predetermined fuel cell among the plurality of fuel cells.

  The air pump 13 includes a motor that is driven and controlled by the control device 41, and takes in air from the outside via an intake (not shown) by the driving force of the motor and compresses the compressed air into the fuel cell stack 11. Supply.

The contactor 30 includes a positive electrode side contactor 31, a negative electrode side contactor 32, a precharge resistor 33, and a precharge contactor 34.
The positive contactor 31 connects or disconnects the positive output terminal of the fuel cell stack 11 and an electrical load (for example, a power drive unit PDU). In the following description, this electric load is also simply referred to as a load. When the positive contactor 31 is in a closed state (on state), the positive output terminal and the load are connected. In addition, when the positive contactor 31 is in an open state (off state), the positive output terminal and the load are disconnected. The control device 41 outputs an open command signal and a close command signal to the positive contactor 31. The positive contactor 31 enters an open state based on an open command from the control device 41. Further, the positive electrode side contactor 31 enters a closed state based on a closing command from the control device 41.

  The negative electrode side contactor 32 connects or disconnects the negative electrode side output terminal and the load among the output terminals of the fuel cell stack 11. When the negative contactor 32 is in a closed state (on state), the negative output terminal is connected to the load. When the negative contactor 32 is in an open state (off state), the negative output terminal and the load are disconnected. The control device 41 outputs an open command signal and a close command signal to the negative contactor 32. The negative contactor 32 enters an open state based on an open command from the control device 41. Further, the negative electrode side contactor 32 is brought into a closed state based on a closing command from the control device 41.

  Here, when the positive electrode side contactor 31 is in an open state (off state), a potential difference may be generated between both terminals of the positive electrode side contactor 31. In this case, when the positive electrode side contactor 31 is closed (ON state), a current (current IMC in FIG. 1) flows to the contact point of the positive electrode side contactor 31 due to this potential difference. Further, when the positive contactor 31 is changed from the open state to the closed state, a jump phenomenon (bouncing) may occur at the contact point, and the contact point may be temporarily opened. If bouncing occurs while current flows through the positive contactor 31, arc discharge may occur at the contact and the contact may be welded. When this contact welding occurs, even if the control device 41 outputs an open command to the positive contactor 31, the positive contactor 31 does not enter the open state. Thus, even if the control device 41 outputs an open command to the positive contactor 31, a state in which the positive contactor 31 does not enter the open state is referred to as a closed failure of the positive contactor 31.

The precharge resistor 33 has a first terminal connected to the fuel cell stack side terminal of the positive contactor 31 and a second terminal connected to the first terminal of the precharge contactor 34.
Among the two terminals, the precharge contactor 34 has a first terminal connected to the precharge resistor 33 and a second terminal connected to the load side terminal of the positive contactor. The control device 41 outputs an open command signal and a close command signal to the precharge contactor 34. The precharge contactor 34 enters an open state based on an open command from the control device 41. Further, the precharge contactor 34 enters a closed state based on a closing command from the control device 41.

  The precharge contactor 34 reduces a potential difference generated between both terminals of the positive contactor 31 when the positive contactor 31 is in an open state. Specifically, the control device 41 closes the precharge contactor 34 when the positive electrode side contactor 31 is in the open state. At this time, a current (current IPC in FIG. 1) flows through the precharge contactor 34 due to a potential difference generated between both terminals of the positive contactor 31. Here, the current IPC flows to the precharge contactor 34 via the precharge resistor 33. The precharge resistor 33 limits the current value of the current IPC. Here, the resistance value of the precharge resistor 33 is selected to be sufficiently large so that the current IPC can be limited to such an extent that the contact does not weld even when bouncing occurs at the contact of the precharge contactor 34. ing. When the positive contactor 31 is open, the potential difference between both terminals of the positive contactor 31 is reduced by closing the precharge contactor 34. By closing the positive electrode side contactor 31 in a state where the potential difference between both terminals of the positive electrode side contactor 31 is reduced, welding of the positive electrode side contactor 31 is suppressed, and the degree of occurrence of a closed failure is reduced.

  The diode 35 is provided in the output circuit on the positive electrode side of the fuel cell stack 11 and suppresses reverse flow of current to the positive electrode side of the fuel cell stack 11.

  The current sensor 37 detects a current IFC supplied from the fuel cell stack 11 to an electric load (for example, a power drive unit PDU), and outputs a detection result signal to the control device 41.

  The voltage sensor 38 detects the voltage between the positive electrode and the negative electrode of the fuel cell stack 11 (that is, the total voltage that is the sum of the voltages of the plurality of fuel cells) VFC, and outputs a detection result signal to the control device 41. .

  The voltage sensor 39 detects a voltage VPDU between the positive electrode and the negative electrode of an electric load (for example, a power drive unit PDU), and outputs a detection result signal to the control device 41.

  The power storage device 50 includes a battery, a capacitor, and the like, and stores the power output from the fuel cell stack 11 and the power regenerated by the travel driving motor M. Further, the power storage device 50 supplies the stored power to the air pump 13 and the motor M for driving when the fuel cell stack 11 is started or the vehicle 1 is accelerated.

  The auxiliary machine 60 includes a compressor of an air conditioner, a downverter that generates a 12V power supply, and the like, and operates with electric power supplied from the fuel cell stack 11 and the power storage device 50.

The voltage regulator (FCVCU) 40 is disposed between the positive and negative electrodes of the fuel cell stack 11 via the contactor 30 and the electric load, and the voltage output from the fuel cell stack 11 is controlled by the control device 41. Adjust the current. The voltage regulator 40 steps down the voltage VBAT to the voltage VFC when the output voltage of the power storage device 50 (voltage VBAT in FIG. 1) is higher than the output voltage (voltage VFC) of the fuel cell stack 11. Then, electric power is supplied to an electric load (for example, a power drive unit PDU).
When the output voltage (voltage VBAT) of the power storage device 50 is lower than the output voltage (voltage VFC) of the fuel cell stack 11, the voltage regulator 40 increases the voltage VBAT to the voltage VFC, The configuration may be such that electric power is supplied to an electrical load (for example, a power drive unit PDU).

  The control device 41 controls the operation of the fuel cell system 10 based on signals output from the switch 2 and detection result signals output from the current sensor 37, the voltage sensor 38, the voltage sensor 39, and a sensor (not shown). Control.

  The fuel cell system 10 is switched between connection and disconnection with respect to the fuel cell stack 11 under the control of the control device 41 in addition to the electric device such as the driving motor M and the power storage device 50 mounted on the vehicle 1. An electric load (for example, a discharge resistor or an electronic load) that can be changed and the load current can be changed may be provided. In this case, the control device 41 can control the discharge to the electric load as the discharge (discharge) at the time of power generation of the fuel cell stack 11.

[Contactor failure detection operation by the fuel cell system controller]
So far, the configuration of the fuel cell system 10 according to the present embodiment has been described. Next, a control operation (that is, a control method of the fuel cell system 10) by the control device 41 of the fuel cell system 10 will be described with reference to FIG. 2 and FIG.
FIG. 2 is a flowchart showing an example of the control operation of the control device 41 according to the embodiment of the present invention. FIG. 3 is a timing chart showing an example of the control operation of the control device 41. Hereinafter, description will be made while associating each step shown in FIG. 2 with each time from time t10 to time t14 shown in FIG. Hereinafter, this time t10 to time t14 is referred to as an output reduction process of the fuel cell stack 11. Further, from the time t10 to the time t14, the time t12 to the time t14 is referred to as a failure detection mode.

  At time t10, the control device 41 starts a power generation stop process of the fuel cell system 10 when detecting a stop signal instructing the stop of the fuel cell system 10 by an input operation of the driver to the switch 2 or the like. At time t10 when the power generation stop process is started, the control device 41 controls the fuel cell system 10 by setting the output voltage (voltage VFC) of the fuel cell stack 11 to the voltage V4. As an example, the voltage V4 is higher than the output voltage (voltage VBAT) of the power storage device 50. In this power generation stop process, the control device 41 stops the gas supply and decreases the output voltage (voltage VFC) of the fuel cell stack 11. The fuel cell system 10 includes a sealing valve (not shown) that blocks inflow of oxidant gas into the fuel cell stack 11 and outflow from the fuel cell stack 11. The control device 41 seals this sealing valve in the power generation stop process. As a result, the fuel cell stack 11 is not supplied with new oxidant gas. After sealing this sealing valve, the control device 41 extracts current from the fuel cell stack 11, thereby consuming oxygen in the sealed fuel cell stack 11 and reducing the concentration. That is, the control device 41 reduces the concentration of the oxidant gas in the fuel cell stack 11 in the process of reducing the output of the fuel cell stack 11 (oxidant reduction process).

  The control device 41 reduces the output voltage (voltage VFC) of the fuel cell stack 11 during this power generation stop process, that is, from time t10 to time t14. Specifically, the control device 41 reduces the voltage VFC to the voltage V4 at time t10, the voltage VFC to the voltage V3 at time t12, the voltage VFC to the voltage V2 at time t13, and the voltage VFC to the voltage V1 at time t14. Let In this example, at time t11 between time t10 and time t12, voltage VFC matches voltage VBAT. The voltage VBAT is kept constant from time t10 to time t14. That is, between time t11 and time t14, voltage VFC is lower than voltage VBAT. Between time t11 and time t14, the control device 41 performs control to decrease the primary voltage of the voltage regulator 40 in accordance with the decrease in the voltage VFC.

At this time, the control device 41 controls the primary voltage of the voltage regulator 40 so as to match the voltage VFC. That is, between the time t10 and the time t12, the primary side voltage of the voltage regulator 40 becomes the same voltage as the voltage VFC. The primary side voltage of the voltage regulator 40 is detected as a voltage VPDU by the voltage sensor 39. That is, the voltage VFC and the voltage VPDU coincide between time t10 and time t12.
By the time t12 when the failure detection mode is started, the precharge contactor 34 is in an open state, and both the positive electrode side contactor 31 and the negative electrode side contactor 32 are in a closed state.

Next, the control device 41 starts the failure detection mode at time t12. The control device 41 performs this failure detection mode in the process of reducing the oxidant in the fuel cell stack 11. That is, from time t12 to time t14, the control device 41 simultaneously performs the oxidant reduction process in the fuel cell stack 11 and the failure detection process for detecting the contactor closed failure. A specific example of the control of the control device 41 in the failure detection mode will be described. The control device 41 opens the positive contactor 31 at time t12 (step S10). At this time, the control device 41 controls the primary side voltage of the voltage regulator 40 to a voltage lower than the voltage VFC by a predetermined voltage Vd. Here, the predetermined voltage is a voltage determined based on the voltage detection accuracy of the voltage sensor 38 and the voltage sensor 39, the magnitude of the voltage drop due to the current IFC, and the like. Specifically, the predetermined voltage Vd determines whether the contactor 30 is open or closed between the voltage VFC detected by the voltage sensor 38 and the voltage VPDU detected by the voltage sensor 39. It is determined in advance based on an experiment or the like so as to produce a difference as much as possible. The predetermined voltage Vd is, for example, 10 [V]. In the following, since the control of the primary voltage of the voltage regulator 40 performed by the control device 41 between time t12 and time t14 is the same as the control at time t12, the description thereof is omitted. .
At this time, if the positive contactor 31 is not closed, a potential difference is generated between the voltage VFC and the voltage VPDU by the predetermined voltage Vd. In addition, when the positive contactor 31 is closed, a potential difference between the voltage VFC and the voltage VPDU hardly occurs.

  Next, the control device 41 acquires the voltage VFC detected by the voltage sensor 38 and the voltage VPDU detected by the voltage sensor 39, respectively. The control device 41 compares the acquired voltage VFC with the voltage VPDU (step S20). Here, when it is determined that the difference between the voltage VFC and the voltage VPDU is larger than the predetermined threshold value Vth (step S20; YES), the control device 41 proceeds with the process to step S30, and the positive contactor It is determined that 31 is not closed. On the other hand, when it is determined that the difference between the voltage VFC and the voltage VPDU is equal to or less than the predetermined threshold value Vth (step S20; NO), the control device 41 proceeds with the process to step S40, and the positive contactor 31 Is determined to have a closed failure. Here, the predetermined threshold value Vth is a value determined based on the predetermined voltage Vd between the voltage VFC and the voltage VPDU described above. For example, the predetermined threshold value Vth is determined to be a half value of the predetermined voltage Vd. In this case, if the predetermined voltage Vd is 10 [V], the predetermined threshold Vth is set to 5 [V].

  Next, at time t13, the control device 41 opens the negative electrode side contactor 32 and closes the precharge contactor 34 (step S50). At this time, if the negative contactor 32 is not closed, a potential difference is generated between the voltage VFC and the voltage VPDU by the predetermined voltage Vd. Further, when the negative electrode side contactor 32 is closed, a potential difference between the voltage VFC and the voltage VPDU hardly occurs.

  Here, the precharge contactor 34 is closed in order to make the reference potential of the voltage VFC detected by the voltage sensor 38 coincide with the reference potential of the voltage VPDU detected by the voltage sensor 39. Here, the reference potentials of the voltage VFC and the voltage VPDU are the potentials of the positive output terminals of the fuel cell stack 11 in this example. Also, by closing the positive contactor 31, the reference potential of the voltage VFC detected by the voltage sensor 38 and the reference potential of the voltage VPDU detected by the voltage sensor 39 can be matched. In this case, since there is a possibility that a close failure may occur by changing the positive contactor 31 from the open state to the closed state, the detection of the close failure of the positive contactor 31 is performed again.

  Next, the control device 41 acquires the voltage VFC detected by the voltage sensor 38 and the voltage VPDU detected by the voltage sensor 39, respectively. Further, the control device 41 compares the acquired voltage VFC with the voltage VPDU (step S60). Here, when the control device 41 determines that the difference between the voltage VFC and the voltage VPDU is larger than the predetermined threshold value Vth (step S60; YES), the process proceeds to step S70, and the negative side contactor It is determined that 32 is not closed. On the other hand, when the control device 41 determines that the difference between the voltage VFC and the voltage VPDU is equal to or smaller than the predetermined threshold value Vth (step S60; NO), the control device 41 proceeds to step S80, and the negative contactor 32 Is determined to have a closed failure.

  Next, at time t14, the control device 41 opens the precharge contactor 34 (step S90) and ends the failure detection mode.

  As described above, the control device 41 detects a closed failure of the contactor 30 by determining whether or not a potential difference is generated between both ends of the contactor 30 when the contactor 30 is opened. At this time, even if the voltage regulator 40 of this embodiment is a case where the secondary side voltage (voltage VBAT) is higher than the primary side voltage (voltage VPDU), the secondary side voltage is reduced to the primary side voltage. Can step down. Therefore, even when the voltage VBAT is higher than the voltage VFC, the control device 41 of the present embodiment steps down the secondary side voltage VBAT to the primary side voltage VFC or less to thereby reduce the fuel cell stack 11. Current IFC can be supplied to the contactor 30. Thereby, the control device 41 of the present embodiment can detect a closed failure of the contactor 30 even when the voltage VBAT is higher than the voltage VFC.

  Here, as a comparison, a conventional voltage regulator will be described. The voltage regulator according to this conventional technique cannot step down the secondary side voltage to the primary side voltage when the secondary side voltage is higher than the primary side voltage. That is, in the conventional technique, the primary voltage (for example, voltage VPDU) of the voltage regulator cannot be made equal to or lower than the secondary voltage (for example, voltage VBAT). For this reason, unless the output voltage (voltage VFC) of the fuel cell stack 11 is higher than the voltage VBAT of the power storage device 50, the closed failure of the contactor 30 cannot be detected. In other words, in the conventional technique, the closed failure detection of the contactor 30 is performed during a period in which the output voltage of the fuel cell stack 11 is high during the process in which the output voltage of the fuel cell stack 11 gradually decreases due to the power generation stop process. For this reason, according to the conventional contactor failure detection method, the state in which the output voltage of the fuel cell stack 11 is high during the power generation stop process is prolonged for the time required for the failure detection mode, and therefore the solid polymer electrolyte membrane may be deteriorated. there were.

  On the other hand, according to the contactor failure detection method of the fuel cell system 10 according to the present embodiment, in the process in which the output voltage of the fuel cell stack 11 gradually decreases due to the power generation stop process, the output voltage of the fuel cell stack 11 is low. Then, the closed failure of the contactor 30 is detected. For this reason, the state where the output voltage of the fuel cell stack 11 is high during the power generation stop process can be shortened as compared with the conventional method. Therefore, according to the contactor failure detection method of the fuel cell system 10 according to the present embodiment, it is possible to suppress damage to the solid polymer electrolyte membrane accompanying the detection of the contactor closed failure.

  In the above description, the failure detection mode is described as being performed in the power generation stop process of the fuel cell system 10, but the present invention is not limited to this. The failure detection mode may be performed in the process of reducing the output power of the fuel cell system 10. For example, the failure detection mode may be performed after the fuel cell system 10 is stopped (during soak), during a travel mode using electric power of the power storage device (during EV travel mode), or during idling stop.

  The present embodiment described above shows an example in carrying out the present invention, and it goes without saying that the present invention is not construed as being limited to the above-described embodiment.

10 Fuel Cell System 11 Fuel Cell Stack (Fuel Cell)
13 Air pump 30 Contactor (switch)
37 Current sensor 38 Voltage sensor 39 Voltage sensor 40 Voltage regulator (voltage converter)
41 Control Device 50 Power Storage Device 60 Auxiliary Machine

Claims (3)

A fuel cell that generates electricity by reaction of anode fuel and cathode oxidant through a membrane;
The load used by the output of the fuel cell, and one end side is connected to the fuel cell side and the other end side is connected to the load side to cut off and supply power from the fuel cell to the load by opening and closing the contacts. A switch to switch,
A voltage capable of stepping down the voltage on the primary side to a predetermined voltage capable of suppressing deterioration of the membrane of the fuel cell, with the load side of the switch connected to the primary side and a power storage device connected to the secondary side A conversion device;
With
In the process of reducing the output of the fuel cell, the voltage conversion device lowers the primary side voltage to the predetermined voltage to detect the closing failure of the contact of the switch. Battery system switch failure detection method. 2. The fuel cell system according to claim 1, wherein the predetermined voltage is a voltage that is stepped down in accordance with a decrease in the output voltage of the fuel cell in a process of reducing the output of the fuel cell. Switch failure detection method. The fuel cell system according to claim 1, wherein the process of reducing the output of the fuel cell includes a process of reducing the oxidant in the fuel cell. Switch failure detection method.

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