JP2012104438A - Fuel battery system and its abnormality detection method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To restrain erroneous detection caused by a shortage of fuel gas supplied to an anode and detect only a steady-state abnormality such as fault in a constituent element electrically connected to a fuel battery.SOLUTION: A fuel battery system of the present invention includes a fuel battery containing one or more fuel battery cells, each having an anode and a cathode formed on both sides of an electrolyte membrane; a gas supply unit which supplies fuel gas and oxidation gas as electricity generation gases to the fuel battery; a voltage monitoring unit which monitors the voltages of fuel battery cells and an hourly change in voltage; and an abnormality monitoring unit which detects abnormality in the monitor voltages monitored by the voltage monitoring unit. The abnormality monitoring unit, when supply of electricity generation gases is once halted and then started back again, raises the set value of a monitoring upper-limit voltage which serves as a reference for abnormality detection.

Description

  The present invention relates to a fuel cell system and an abnormality detection method thereof.

  In order to avoid malfunction of the fuel cell and deterioration of the fuel cell, the fuel cell system is usually provided with a voltage monitoring device, and the cell voltage of the fuel cell is monitored. One of the items of voltage to be monitored is an upper limit voltage of the cell voltage, and the generation of a voltage higher than the set upper limit voltage is monitored. For example, a component that can generate electric power, such as a secondary battery, is usually provided separately from the fuel cell, and monitoring is performed when current flows from the component into the fuel cell. There is a possibility that the value of the cell voltage exceeds the logical electromotive force, resulting in deterioration of the fuel cell. Therefore, it is desirable to monitor the cell voltage so as not to exceed the upper limit voltage so that such a current does not flow into the fuel cell.

  As an example of the prior art, Patent Document 1 discloses that when the value of the voltage monitored by the voltage monitoring device exceeds the value of the no-load voltage (also referred to as “open circuit voltage”), the fuel A technique for determining current inflow from an external component to the battery or failure of the voltage monitoring device itself is disclosed.

JP 2003-346858 A

  FIG. 8 is an explanatory diagram showing a transient abnormal voltage generated due to a hydrogen deficient state. When hydrogen supply is started to avoid this from a state where hydrogen as a fuel gas is deficient in the anode of the fuel cell (so-called hydrogen deficient state), the generated cell voltage is transient as shown in FIG. Therefore, an abnormal voltage higher than the voltage at no load is generated. In the voltage monitoring of the prior art, even if this abnormal voltage occurs transiently, it is determined that the current flows into the fuel cell from an external component or that the voltage monitoring device itself fails. That is, in the prior art, a transient abnormal voltage is generated due to lack of hydrogen as a fuel gas and is not a steady abnormality, and a steady state such as a failure of a component electrically connected to the fuel cell. There is a problem that it cannot be distinguished from a case of abnormal abnormality.

  Therefore, an object of the present invention is to provide a technique capable of suppressing erroneous detection that occurs due to lack of fuel gas supplied to the anode.

  SUMMARY An advantage of some aspects of the invention is to solve at least a part of the problems described above, and the invention can be implemented as the following forms or application examples.

[Application Example 1]
A fuel cell system comprising a fuel cell having at least one fuel cell in which an anode and a cathode are formed on both sides of an electrolyte membrane, and a gas supply for supplying a fuel gas and an oxidizing gas as a power generation gas to the fuel cell A voltage monitoring unit that monitors the voltage of the fuel cell and a time change of the voltage, and an abnormality monitoring unit that detects an abnormality of the monitoring voltage monitored by the voltage monitoring unit, the abnormality monitoring unit, A fuel cell system characterized in that when the supply of gas for power generation is stopped and then the supply is started again, the set value of the monitoring upper limit voltage serving as a reference for detecting an abnormality is increased.
According to the above configuration, it is possible to suppress the abnormal voltage generated in the prior art from being detected as abnormal, and it is possible to suppress erroneous determination of the abnormality monitoring unit.

[Application Example 2]
In the fuel cell system according to Application Example 1, when the abnormality monitoring unit stops the supply of the power generation gas and then a fuel gas shortage occurs at the anode of the fuel cell, A fuel cell system characterized by raising a set value of the monitoring upper limit voltage when starting the supply of the gas for power generation.
When a fuel gas shortage occurs at the anode of the fuel cell, when the supply of gas for power generation is started, the abnormal voltage described in the related art is excessively generated. It is possible to suppress abnormally generated abnormal voltage from being detected as abnormal, and it is possible to suppress erroneous determination of the abnormality monitoring unit.

[Application Example 3]
In the fuel cell system according to Application Example 1, the abnormality monitoring unit may change a time change of the monitoring voltage monitored by the voltage monitoring unit from negative to positive after the supply of the power generation gas is stopped. The fuel cell system is characterized in that when the supply of the gas for power generation is started after the time point of the change, the set value of the monitoring upper limit voltage is increased.
After the supply of the gas for power generation is stopped, after the time change of the monitoring voltage monitored by the voltage monitoring unit changes from negative to positive, the fuel cell lacking in the anode of the fuel cell described in the related art Since the state has occurred, when the supply of gas for power generation is started, the abnormal voltage described in the related art is excessively generated. Therefore, according to the above configuration, the abnormal voltage generated transiently is regarded as abnormal. Detection can be suppressed, and erroneous determination of the abnormality monitoring unit can be suppressed.

[Application Example 4]
The fuel cell system according to Application Example 1, wherein the abnormality monitoring unit stops the supply of the power generation gas until a fuel gas shortage occurs at the anode of the fuel cell. A fuel cell system characterized in that when the supply of the power generation gas is started after the elapse of a predetermined time set in advance as a time, the set value of the monitoring upper limit voltage is increased.
The fuel cell described in the prior art after the elapse of a predetermined time set in advance as the elapsed time until the fuel gas shortage occurs at the anode of the fuel cell after the supply of power generation gas is stopped Since the fuel gas shortage occurs at the anode of the cell, the abnormal voltage described in the prior art is excessively generated when the supply of power generation gas is started. Therefore, it is possible to suppress the abnormal voltage generated in the error from being detected as abnormal, and it is possible to suppress erroneous determination of the abnormality monitoring unit.

[Application Example 5]
In the fuel cell system according to Application Example 1, the abnormality monitoring unit oxidizes a catalyst carrier that supports a catalyst included in a cathode of the fuel cell after stopping the supply of the gas for power generation. A fuel cell system, wherein when a state occurs, when the supply of the power generation gas is started, a set value of the monitoring upper limit voltage is increased.
After the supply of gas for power generation is stopped, when a state occurs in which the catalyst carrier carrying the catalyst contained in the cathode of the fuel cell is oxidized, the fuel gas is applied to the anode of the fuel cell described in the prior art. Therefore, when the supply of power generation gas is started, the abnormal voltage described in the related art is excessively generated. According to the above configuration, the abnormal voltage generated transiently is generated. Detection of an abnormality can be suppressed, and erroneous determination of the abnormality monitoring unit can be suppressed.

[Application Example 6]
A fuel cell system comprising a fuel cell having at least one fuel cell in which an anode and a cathode are formed on both sides of an electrolyte membrane, and a gas supply for supplying a fuel gas and an oxidizing gas as a power generation gas to the fuel cell A voltage monitoring unit that monitors the voltage of the fuel cell and a time change of the voltage, and an abnormality monitoring unit that detects an abnormality of the monitoring voltage monitored by the voltage monitoring unit, the abnormality monitoring unit, When a fuel gas shortage occurs at the anode of the fuel battery cell, when the supply amount of the fuel gas is increased, the set value of the monitoring upper limit voltage serving as a reference for detecting an abnormality is increased. A fuel cell system.
When the fuel gas shortage occurs at the anode of the fuel cell, when the supply amount of the fuel gas is increased, the abnormal voltage described in the related art is excessively generated. Therefore, it is possible to suppress the abnormal voltage generated in the error from being detected as abnormal, and it is possible to suppress erroneous determination of the abnormality monitoring unit.

[Application Example 7]
A fuel cell system comprising a fuel cell having at least one fuel cell in which an anode and a cathode are formed on both sides of an electrolyte membrane, and a gas supply for supplying a fuel gas and an oxidizing gas as a power generation gas to the fuel cell A voltage monitoring unit that monitors the voltage of the fuel cell and a time change of the voltage, and an abnormality monitoring unit that detects an abnormality of the monitoring voltage monitored by the voltage monitoring unit, the abnormality monitoring unit, When a state in which the catalyst carrier carrying the catalyst contained in the cathode of the fuel cell is oxidized is generated, when the supply amount of the fuel gas is increased, a monitoring upper limit voltage is set as a reference for detecting an abnormality A fuel cell system characterized by increasing the value.
When the state of oxidizing the catalyst carrier carrying the catalyst contained in the cathode of the fuel cell occurs, when the amount of fuel gas supplied is increased, the abnormal voltage described in the prior art is excessively generated. According to the above configuration, it is possible to suppress the abnormal voltage generated transiently from being detected as abnormal, and it is possible to suppress erroneous determination of the abnormality monitoring unit.

[Application Example 8]
The fuel cell system according to any one of Application Example 1 to Application Example 7, wherein the abnormality monitoring unit does not change from a positive state to a zero state and then to a negative state after the monitoring voltage changes from a positive state to a zero state And determining that a failure has occurred in a component electrically connected to the fuel cell.
According to the above configuration, the abnormal voltage generated transiently is suppressed from being detected as abnormal, the erroneous determination of the abnormality monitoring unit is suppressed, and a failure occurs in the component electrically connected to the fuel cell. It is possible to determine only that

  The present invention can be realized in various forms, for example, in various forms such as a fuel cell system and an abnormality detection method of the fuel cell system.

It is a block diagram which shows the structural example of the fuel cell system in 1st Example. It is a flowchart which shows the voltage monitoring control routine in 1st Example. It is a flowchart which shows the abnormality monitoring control routine in 1st Example. It is explanatory drawing which shows the change of the cell voltage after the stop of a fuel cell system. It is explanatory drawing which shows the change of the cell voltage of a no-load state at the time of starting hydrogen supply in the state in which hydrogen deficiency has generate | occur | produced. It is a flowchart which shows the abnormality monitoring control routine in 2nd Example. It is a flowchart which shows the abnormality monitoring control routine in 3rd Example. It is explanatory drawing shown about the transient abnormal voltage which arises resulting from a hydrogen deficient state.

Embodiments of the present invention will be described in the following order based on examples.
A. First embodiment:
B. Second embodiment:
C. Third embodiment:
D. Variations:

A. First embodiment:
A1. Configuration example of fuel cell system:
FIG. 1 is a block diagram showing a configuration example of the fuel cell system in the first embodiment. This fuel cell system 10 shows a fuel cell system mounted on a vehicle as an example.

  The fuel cell system 10 includes a fuel cell 100, an anode gas (fuel gas) supply unit 200 and a cathode gas (oxidizing gas) supply unit 300, a cooling device 400, a monitor unit 500, a power control unit 600, and a control unit. 700.

  The fuel cell 100 is formed by an electrochemical reaction between a fuel gas (hydrogen) as an anode gas supplied to an anode and an oxidizing gas (air, strictly speaking, oxygen contained in air) as a cathode gas supplied to a cathode. Generate power.

  The fuel cell 100 is a fuel cell composed of fuel cells using a solid polymer electrolyte membrane. The fuel cell 100 has a stack structure in which a plurality of fuel cells are stacked. Although not shown, the fuel cell basically has a configuration in which a membrane-electrode assembly (MEA) is sandwiched between separators. The MEA includes an electrolyte membrane made of an ion exchange membrane, a catalyst electrode (also referred to as “anode side catalyst electrode” or simply “anode”) formed on the anode side surface of the electrolyte membrane, and a cathode side surface of the electrolyte membrane. It is composed of the catalyst electrode formed above (also referred to as “cathode side catalyst electrode” or simply “cathode”). Between the MEA and the separator, gas diffusion layers (GDL) are respectively provided on the anode side and the cathode side. In addition, a groove-like gas flow path for flowing an anode gas or a cathode gas is formed on the surface in contact with the separator and the gas diffusion layer. However, a gas flow path portion may be separately provided between the separator and the gas diffusion layer. In addition, each component formed between the electrolyte membrane and the anode-side separator may be collectively referred to as an “anode”. In addition, each component formed between the electrolyte membrane and the cathode separator may be collectively referred to as a “cathode”.

  The anode gas supply unit 200 includes a hydrogen gas tank 210 that stores high-pressure hydrogen gas as an anode gas (fuel gas), an anode gas supply channel 220 for supplying the hydrogen gas in the hydrogen gas tank 210 to the fuel cell 100, And an anode gas circulation passage 230 for returning hydrogen offgas as anode offgas (fuel offgas) discharged from the fuel cell 100 to the anode gas supply passage 220. The anode gas supply channel 220 includes an open / close valve 222 that shuts off or allows the supply of hydrogen gas from the hydrogen gas tank 210, a regulator 224 that adjusts the pressure of the hydrogen gas, and a hydrogen supply unit 226 that adjusts the flow rate of the hydrogen gas. And are provided. The anode gas circulation channel 230 is provided with a hydrogen gas pump 232 that sends out hydrogen off-gas as the anode off-gas in the anode gas circulation channel 230 to the anode gas supply channel 220 side. Further, a discharge flow path 238 connected to the exhaust port 350 is connected to the anode gas circulation flow path 230 via a gas-liquid separation unit 234 and an exhaust drainage valve 236. The gas-liquid separator 234 collects moisture contained in the hydrogen off gas. The exhaust / drain valve 236 discharges the hydrogen off-gas containing moisture collected by the gas-liquid separator 234 and impurities in the anode gas circulation channel 230. The hydrogen off-gas discharged from the exhaust / drain valve 236 is exhausted from the exhaust port 350 to the atmosphere as exhaust gas. The open / close valve 222, the regulator 224, the hydrogen supply unit 226, the hydrogen gas pump 232, the gas-liquid separation unit 234, and the exhaust / drain valve 236 operate according to instructions from the control unit 700.

  The cathode gas supply unit 300 takes in air as cathode gas (oxidizing gas) through the intake port 310 and compresses and sends the air, and cathode gas supply for supplying air (air) to the fuel cell 100. A flow path 330 and a cathode off gas discharge flow path 340 for discharging the cathode off gas (oxidation off gas) discharged from the fuel cell 100 from the exhaust port 350 are provided. The cathode off gas discharge channel 340 is provided with a back pressure adjustment valve 342 for adjusting the pressure of the cathode gas (oxidizing gas) in the fuel cell 100. In the cathode gas supply channel 330 and the cathode offgas discharge channel 340, a humidification unit 360 that humidifies the cathode gas (oxidation gas) pumped from the compressor 320 using the cathode offgas (oxidation offgas) discharged from the fuel cell 100. Is provided. The cathode off-gas that has undergone moisture exchange or the like in the humidifying unit 360 is exhausted from the exhaust port 350 to the atmosphere as exhaust gas. The compressor 320, the back pressure adjustment valve 342, and the humidification unit 360 operate according to instructions from the control unit 700.

  The cooling device 400 includes a cooling unit 410, a refrigerant supply passage 420 that supplies the refrigerant to the fuel cell 100, and a refrigerant discharge passage 430 that returns the refrigerant discharged from the fuel cell to the fuel cell 100. The cooling unit 410 circulates the refrigerant by supplying the refrigerant to the fuel cell 100 via the refrigerant supply channel 420 and receiving the refrigerant after being provided for cooling of the fuel cell 100 via the refrigerant discharge channel 430. Then, the fuel cell 100 is cooled. As the refrigerant, water, antifreeze, or the like can be used.

  The monitor unit 500 includes a cell voltage monitor 510 that measures the cell voltage between the fuel cells, a voltage sensor 520 that measures the output voltage of the fuel cell 100, and a current sensor 530 that measures the output current. Note that the cell voltage monitor 510, the voltage sensor 520, and the current sensor 530 are connected to the control unit 700, and the measurement results measured by each element are delivered to the control unit 700 in accordance with instructions from the control unit 700. It is.

  The power control unit 600 includes a secondary battery 610, a secondary battery control unit 620, a motor 630, an output control unit 640, various auxiliary machine control units (not shown), and the like. The secondary battery control unit 620 controls charging / discharging of the secondary battery 610. The motor 630 constitutes a main power source of a vehicle on which the fuel cell system 10 is mounted. The output control unit 640 controls the supply of electric power from the fuel cell 100 or the secondary battery 610 to the motor 630. For example, when the motor 630 is a three-phase AC motor, the output control unit 640 includes a three-phase inverter that converts a direct current into a three-phase alternating current. The accessory control unit controls the supply of electric power for driving each device such as the hydrogen gas pump 232 and the compressor 320, for example.

  The control unit 700 is configured as a computer system mainly including a CPU 710, a memory 720, and an input / output unit 730. The input / output unit 730 connects various actuators, various sensors, various switches, and the like via control signal lines (not shown). Examples of the various actuators include the on-off valve 222, the regulator 224, the hydrogen supply unit 226, the hydrogen gas pump 232, the compressor 320, the back pressure adjustment valve 342, a cooling pump (not shown) included in the cooling unit 410, a cooling fan, and the like. . Examples of the various sensors include the voltage sensor 520, the current sensor 530, a temperature sensor (not shown), a pressure sensor, a humidity sensor, and a flow rate sensor. Examples of the various switches include a start switch 740 that starts an electric vehicle on which the fuel cell system 10 is mounted.

  The memory 720 stores various computer programs (not shown) mainly for controlling the fuel cell system 10, and the CPU 710 operates as each functional block by executing these computer programs. For example, the CPU 710 functions as the power generation control unit 710a, the voltage monitoring control unit 710b, and the abnormality monitoring control unit 710c by executing the computer program of the power generation control routine, the voltage monitoring control routine, and the abnormality monitoring control routine. . The voltage monitoring control routine of the voltage monitoring control unit 710b and the abnormality monitoring control routine of the abnormality monitoring control unit 710c will be described in detail below.

  The anode gas supply unit 200 and the cathode gas supply unit 300 correspond to the gas supply unit of the present invention. The cell voltage monitor 510 and the voltage monitoring control unit 710b correspond to the voltage monitoring unit of the present invention. Further, the abnormality monitoring control unit 710c corresponds to the abnormality monitoring unit of the present invention.

A2. Voltage monitoring control routine:
FIG. 2 is a flowchart showing a voltage monitoring control routine in the first embodiment. This voltage monitoring control routine is executed with dark current, specifically, with the electric power stored in the secondary battery 610 before the electric vehicle is started. As shown in the figure, when the process is started, the CPU 710 measures the cell voltage Vcell of the fuel cell via the cell voltage monitor 510 (step S100), and calculates the time change Vcell / dt of the measured cell voltage Vcell ( Step S110) and accumulation of the measured cell voltage Vcell and its time change Vcell / dt (step S120) are repeatedly executed. In addition, what is necessary is just to perform this repetition at a fixed time interval, for example. In this way, it is easy to calculate the time change in step S110. However, if the time of measurement of the cell voltage Vcell in step S100 is known, it is not always necessary to execute the measurement at regular time intervals. The measurement of the cell voltage Vcell is performed for each fuel cell. However, the process may be executed for a fuel battery cell in which a hydrogen deficient state is most likely to occur in the anode among a plurality of fuel battery cells having a stack structure. It should be noted that the fuel cell in which the hydrogen deficient state is most likely to occur may be appropriately selected depending on the hydrogen gas flow path structure in the fuel cell 100. For example, the fuel cell farthest from the entrance to the fuel cell 100 of the anode gas supply unit 200 is selected.

A3. Abnormality monitoring control routine:
FIG. 3 is a flowchart showing an abnormality monitoring control routine in the first embodiment. This abnormality monitoring control routine is a start-up abnormality monitoring control routine that is executed in response to the start switch 740 being pushed by the operator and the fuel cell system 10 is activated. It is assumed that a monitoring upper limit voltage Vup, which will be described later, is set to a standard upper limit value Vα at the start of the startup abnormality monitoring control routine. As shown in the figure, when the process is started, the CPU 710 first determines whether or not supply of hydrogen gas, which is anode gas (fuel gas), to the fuel cell 100 is started by the anode gas supply unit 200. (Step S200). Here, when it is determined that the supply of hydrogen gas is not started, the CPU 710 repeats the process of step S200 and waits for the supply of hydrogen gas to start.

  If it is determined in step S200 that the supply of hydrogen gas has started, the CPU 710 further determines that the supply of hydrogen gas is the cell voltage Vcell of the fuel cell after the operation of the fuel cell system 10 is stopped. It is determined whether or not it is after the sign of the time change dVcell / dt has changed from negative to positive (step S210). In addition, since the load with respect to the fuel cell 100 is a no-load state, the cell voltage Vcell of the fuel cell after the operation stop of the fuel cell system is usually called an open circuit cell voltage (cell voltage at no load) Vocv. The time change is also expressed as dVocv / dt.

  The determination in step S200 is based on the following reason. FIG. 4 is an explanatory diagram showing changes in cell voltage after the fuel cell system is stopped. After the operation of the fuel cell system 10 is stopped, the hydrogen gas remaining in the anode is consumed over time, so that the cell voltage Vcell (open circuit cell voltage Vocv) is decreased as shown in the figure, dVocv. / Dt <0. When a shortage of hydrogen begins to occur in the anode, oxygen gas leaks from the cathode to the anode via the electrolyte membrane, and increases with time, resulting in dVocv / dt> 0. Thereafter, the cell voltage Vcell (open circuit cell voltage Vocv) decreases again to dVocv / dt <0, eventually becomes zero and dVocv / dt = 0. Accordingly, after the sign of dVocv / dt changes from negative to positive, it is considered that a hydrogen deficiency state (hydrogen deficiency state) has occurred. Therefore, the determination in step S210 is performed in a state where a hydrogen deficiency has occurred. It is determined whether or not the supply of hydrogen gas has been started.

  If it is determined that the start of hydrogen gas supply is not after the sign of dVocv / dt has changed from negative to positive, the supply of hydrogen gas is started before the hydrogen deficient state occurs. Therefore, the CPU 710 keeps the monitoring voltage upper limit value Vup as the standard upper limit value Vα (step S220), and starts normal abnormality monitoring control (step S230). In the normal abnormality monitoring control, it is monitored whether the measured cell voltage Vcell exceeds the monitoring voltage upper limit value Vup (standard upper limit value Vα). To do.

  On the other hand, when it is determined that the start of the supply of hydrogen gas is after the sign of dVocv / dt has changed from negative to positive, the supply of hydrogen gas is started in a hydrogen deficient state, as described in the prior art. Since it is considered that a transient abnormal voltage occurs, the CPU 710 changes the monitoring voltage upper limit value Vup from the standard upper limit value Vα to the transient upper limit value Vβ so as not to detect the transient abnormal voltage as an abnormal voltage (step S240). ).

Note that the standard upper limit value Vα is a state in which hydrogen gas (H ₂ ) and air (Air) are sufficiently supplied to the fuel cell 100 and in a no-load state, that is, in a state where the output current Io = 0. The cell voltage Vcell is set to the voltage value when the time change dVcell / dt = 0. Further, the transient upper limit value Vβ is set to the maximum value of the transient abnormal voltage generated when the hydrogen supply is started in a hydrogen deficient state. The standard upper limit value Vα and the transient upper limit value Vβ are determined by actually measuring in advance. However, it is preferable that the standard upper limit value Vα and the transient upper limit value Vβ are set based on the actual measurement values, taking into account measurement errors and the like and adding a margin to the actual measurement values. Moreover, it may be updated by periodically measuring. In addition, the present invention is not necessarily limited to this, and the standard upper limit value and the transient upper limit value that are allowed as the voltage of the fuel cell can be arbitrarily set based on the measured values.

  When the monitoring voltage upper limit value Vup is changed to the transient upper limit value Vβ, the CPU 710 determines whether or not the measured cell voltage Vcell (open circuit cell voltage Vocv) is higher than the standard upper limit value Vα (step S250).

  When it is determined that the measured cell voltage Vcell (open circuit cell voltage Vocv) is higher than the standard upper limit value Vα, dVocv is equal to or longer than a predetermined time Tj from the time when dVocv / dt> 0 to dVocv / dt = 0. It is determined whether or not the state of / dt = 0 continues (step S260). This determination is performed based on the following reason.

  FIG. 5 is an explanatory diagram showing changes in the cell voltage in the no-load state when hydrogen supply is started in a state where hydrogen shortage occurs. As indicated by the solid line in the figure, after the time change of the cell voltage Vcell in the no-load state (open circuit cell voltage Vocv) becomes dVocv / dt> 0 and becomes higher than the standard upper limit value Vα, the transient upper limit value Vβ When dVocv / dt = 0 after dVocv / dt = 0, this is a case where a transient abnormal voltage has occurred as described in the conventional example, and is connected to the fuel cell 100. It is thought that it is not the occurrence of a steady abnormal voltage due to a failure of an external element. On the other hand, as indicated by a broken line in the figure, when the state of dVocv / dt = 0 continues, it is considered that a steady abnormal voltage is generated and a failure of an external element connected to the fuel cell 100 occurs. . Therefore, in step S260, in order to distinguish between the occurrence of a steady abnormal voltage and the generation of a transient abnormal voltage, a predetermined time Tj or more dVocv / It is determined whether or not the state of dt = 0 continues. Note that the predetermined time Tj is appropriately set in consideration of the transition change time.

  Here, when it is determined that dVocv / dt = 0 continues for a predetermined time Tj or longer, the CPU 710 has generated a steady abnormal voltage, for example, two due to a failure of the secondary battery control unit 620. It is determined that a failure of an external element such as a current inflow from the secondary battery 610 or a failure of the cell voltage monitor 510 has occurred (step S270), and the occurrence of an abnormality is notified using a not-shown notification means (step S280).

  On the other hand, if it is determined that dVocv / dt = 0 does not continue for a predetermined time Tj or longer, the CPU 710 generates a transient abnormal voltage and not a steady abnormal voltage. After determining (step S290) and returning the monitoring voltage upper limit value Vup to the standard upper limit value Vα (step S300), normal abnormality monitoring control is started (step S230).

  After the notification of the occurrence of abnormality in step S280 and after the start of normal abnormality monitoring control in step S230, this startup abnormality monitoring control routine is terminated. Note that after the abnormality occurrence notification, the monitoring voltage upper limit value Vup remains the transient upper limit value Vβ until the operation of the fuel cell system 10 is stopped.

  In the abnormality monitoring control routine in the first embodiment described above, the transient abnormal voltage generated when the supply of hydrogen gas is started in the lack of hydrogen state when the fuel cell system is started is mistaken as the steady abnormal voltage. In addition to suppressing the detection, the occurrence of a steady abnormal voltage, for example, the failure of an external element such as a current inflow from the secondary battery due to a failure of the secondary battery control unit or a cell voltage monitor failure. Can be detected separately from the case of occurrence of a transient abnormal voltage.

B. Second embodiment:
FIG. 6 is a flowchart showing an abnormality monitoring control routine in the second embodiment. Since the second embodiment is exactly the same except that step S210 of the abnormality monitoring control routine in the first embodiment shown in FIG. 3 is changed to step S210B, only the processing of step S210B will be described below. In addition, illustration and description of the configuration of the fuel cell system and the voltage monitoring control routine are omitted.

  In step S <b> 210 </ b> B, CPU 710 determines whether the start of hydrogen gas supply has been executed after a predetermined time Tlim has elapsed since the operation of fuel cell system 10 was stopped. If it is determined that the supply of hydrogen gas has started after a lapse of the predetermined time Tlim, the supply of hydrogen gas is started in a hydrogen deficient state, and the transient abnormal voltage described in the prior art is generated. Therefore, the CPU 710 changes the monitoring voltage upper limit value Vup from the standard upper limit value Vα to the transient upper limit value Vβ so as not to detect a transient abnormal voltage as an abnormal voltage (step S240). On the other hand, when it is determined that the supply of hydrogen gas has started before the predetermined time Tlim has elapsed, the supply of hydrogen gas is started before the hydrogen shortage state occurs, and the transient abnormal voltage described in the conventional example is generated. Therefore, the CPU 710 keeps the monitoring voltage upper limit value Vup as the standard upper limit value Vα (step S220).

  The determination in step S210 is based on the following reason. That is, it can be considered that the air sucked from the tail pipe of the cathode-side vehicle finally passes through the electrolyte membrane and reaches the anode from the cathode, contributing to a hydrogen deficient state. Therefore, if the length of the pipe from the tail pipe of the vehicle to the air supply port of the fuel cell and the air diffusion speed are known, the time until the anode is in a hydrogen deficient state can be estimated. Therefore, the determination in step S210 is performed by determining in advance the time from the stop of the operation of the fuel cell system until the anode is in a hydrogen deficient state, and whether or not the predetermined time Tlim thus obtained has elapsed. It is determined whether or not the supply of hydrogen gas is started.

  Also in the abnormality monitoring control routine in the second embodiment described above, the transient abnormal voltage generated when the supply of hydrogen gas is started in a hydrogen deficient state when the fuel cell system is started is referred to as a steady abnormal voltage. In addition to preventing false detections, the occurrence of steady abnormal voltages such as current inflows from secondary batteries and cell voltage monitor failures due to secondary battery control unit failures, etc. Can be detected separately from the case where a transient abnormal voltage occurs.

C. Third embodiment:
FIG. 7 is a flowchart showing an abnormality monitoring control routine in the third embodiment. The abnormality monitoring control in the first embodiment and the second embodiment corresponds to the case where the supply of hydrogen gas is started in a hydrogen deficient state when the fuel cell system is started. However, even when the fuel cell system is in operation, a hydrogen deficient state may occur. Therefore, the abnormality monitoring control routine of the third embodiment is a hydrogen shortage operation abnormality monitoring control routine corresponding to a case where a hydrogen shortage state occurs during operation of the fuel cell system. This abnormality monitoring control routine is started in conjunction with the start of power generation control.

  As shown in the figure, when the process is started, the CPU 710 first starts normal abnormality monitoring control (step S400). Then, it is determined whether or not the measured cell voltage Vcell is negative (Vcell <0) (step S410).

  If it is determined that Vcell <0, a shortage of hydrogen gas or air is assumed. First, after increasing the air flow rate (step S420), whether or not the cell voltage Vcell increases. That is, it is determined whether dVcell / dt> 0 is satisfied (step S430).

  On the other hand, if Vcell> 0 in step S410, it is assumed that neither hydrogen gas nor air is in a deficient state but a normal operating state, so CPU 710 determines that this routine is terminated in step S440. Steps S410 to S430 are repeatedly executed.

  If it is determined in step S430 that dVcell / dt> 0, the air is insufficient and not in a hydrogen-deficient state. Therefore, until the CPU 710 determines in step S440 to end this routine, the process of steps S410 to S430 is performed. Repeat the process.

  On the other hand, if it is determined in step S430 that dVcell / dt> 0 is not satisfied, the CPU 710 determines that there is a shortage of hydrogen, stops power generation of the fuel cell 100 as a no-load state, and stops normal abnormality monitoring control ( Step S450).

  Then, the CPU 710 increases the flow rate of hydrogen gas (step S460), and changes the monitoring voltage upper limit value Vup from the standard upper limit value Vα to the transient upper limit value Vβ so as not to detect a transient abnormal voltage as an abnormal voltage. (Step S470).

  Next, the CPU 710 determines whether or not the measured cell voltage Vcell (open circuit cell voltage Vocv) is higher than the standard upper limit value Vα (step S480).

  When it is determined that the measured cell voltage Vcell (open circuit cell voltage Vocv) is higher than the standard upper limit value Vα, the CPU 710 further performs a predetermined time from when dVovv / dt> 0 to dVocv / dt = 0. It is determined whether or not the state of dVocv / dt = 0 continues for Tj or more (step S490). This determination is the same as step S260 (see FIGS. 3 and 6) in the first and second embodiments.

  Here, when it is determined that dVocv / dt = 0 continues for a predetermined time Tj or longer, the CPU 710 has generated a steady abnormal voltage, for example, two due to a failure of the secondary battery control unit 620. It is determined that a failure of an external element such as a current inflow from the secondary battery 610 or a failure of the cell voltage monitor 510 has occurred (step S500). Then, the occurrence of an abnormality is notified using notifying means (not shown) (step S510), and this abnormality management control routine is terminated.

  On the other hand, if dVocv / dt = 0 does not continue for the predetermined time Tj or longer, the CPU 710 determines that there is no abnormality because it is a transient abnormal voltage and not a steady abnormal voltage (step S520). ). Then, after returning the monitoring voltage upper limit value Vup to the standard upper limit value Vα (step S530), normal power generation is resumed and normal abnormality monitoring control is started (step S540). Repeat the process.

  Even during operation of the fuel cell system, the operation may be performed in a hydrogen deficient state. When the flow rate of hydrogen gas is increased in order to eliminate the hydrogen deficient state, it is assumed that a transient abnormal voltage is generated as in the start-up of the first and second embodiments. In the abnormality monitoring control routine in the third embodiment described above, when the fuel cell system is in operation, it is determined whether the hydrogen gas is in shortage, and the hydrogen gas flow rate is increased to eliminate the hydrogen shortage state. In addition to suppressing erroneous detection of transient abnormal voltage occurring in the battery as a steady abnormal voltage, the generation of a steady abnormal voltage, for example, a current from a secondary battery due to a failure of a secondary battery control unit It is possible to detect a case where a failure of an external element such as an inflow or a failure of a cell voltage monitor has occurred and distinguish it from a case where a transient abnormal voltage occurs.

D. Variations:
In addition, this invention is not restricted to said Example and embodiment, In the range which does not deviate from the summary, it is possible to implement in various aspects.

D1. Modification 1:
In the first embodiment and the second embodiment, the start-up abnormality monitoring control routine has been described as an example, and in the third embodiment, the hydrogen deficient operation compatible abnormality monitoring control routine has been described as an example. The present invention is not limited to this, and the first embodiment, the third embodiment, the second embodiment, and the third embodiment may be applied in combination.

D2. Modification 2:
In the above embodiment, the fuel cell system mounted on the vehicle is shown as an example, but the present invention can be applied not only to the vehicle but also to various moving bodies such as a motorcycle, a ship, an airplane, and a robot. Further, the present invention is not limited to a fuel cell system mounted on a moving body, but can be applied to a stationary fuel cell system and a portable fuel cell system.

10 ... Fuel cell system 71 ... CPU
DESCRIPTION OF SYMBOLS 100 ... Fuel cell 200 ... Anode gas supply part 210 ... Hydrogen gas tank 220 ... Anode gas supply flow path 222 ... On-off valve 224 ... Regulator 226 ... Hydrogen supply part 230 ... Anode gas circulation flow path 232 ... Hydrogen gas pump 234 ... Gas-liquid separation part 236 ... Exhaust drain valve 238 ... Discharge flow path 300 ... Cathode gas supply section 310 ... Intake port 320 ... Compressor 330 ... Cathode gas supply flow path 340 ... Cathode off-gas discharge flow path 342 ... Back pressure adjustment valve 350 ... Exhaust port 360 ... Humidification Unit 400 ... Cooling device 410 ... Cooling unit 420 ... Refrigerant supply channel 430 ... Refrigerant discharge channel 500 ... Monitor unit 510 ... Cell voltage monitor 520 ... Voltage sensor 530 ... Current sensor 600 ... Power control unit 610 ... Secondary battery 620 ... Secondary battery control unit 630 ... motor (M)
640 ... Output control unit 700 ... Control unit 710 ... CPU
710a ... Power generation control unit 710b ... Voltage monitoring control unit 710c ... Abnormality monitoring control unit 720 ... Memory 730 ... Input / output unit 740 ... Start switch

Claims (11)

A fuel cell system,
A fuel cell having one or more fuel cells each having an anode and a cathode formed on both sides of the electrolyte membrane;
A gas supply unit for supplying a fuel gas and an oxidizing gas as a power generation gas to the fuel cell;
A voltage monitoring unit for monitoring the voltage of the fuel cell and the time change of the voltage;
An abnormality monitoring unit for detecting an abnormality of the monitoring voltage monitored by the voltage monitoring unit;
With
The abnormality monitoring unit raises a set value of a monitoring upper limit voltage serving as a reference for detecting an abnormality when the supply of gas for power generation is stopped and then the supply is started again. system. The fuel cell system according to claim 1,
The abnormality monitoring unit is configured to start supplying the power generation gas when the fuel gas shortage occurs in the anode of the fuel cell after the supply of the power generation gas is stopped. A fuel cell system characterized by raising a set value of a monitoring upper limit voltage. The fuel cell system according to claim 1,
The abnormality monitoring unit stops the supply of the power generation gas after the time when the time change of the monitoring voltage monitored by the voltage monitoring unit changes from negative to positive after stopping the supply of the power generation gas. When the supply is started, the set value of the monitoring upper limit voltage is increased. The fuel cell system according to claim 1,
The abnormality monitoring unit, after stopping the supply of the power generation gas, after the elapse of a predetermined time set in advance as an elapsed time until a fuel gas shortage occurs at the anode of the fuel cell. When the supply of the power generation gas is started, the set value of the monitoring upper limit voltage is increased. The fuel cell system according to claim 1,
The abnormality monitoring unit, after stopping the supply of the power generation gas, when the state of oxidizing the catalyst carrier supporting the catalyst contained in the cathode of the fuel cell occurs, When the supply is started, the set value of the monitoring upper limit voltage is increased. A fuel cell system,
A fuel cell having one or more fuel cells each having an anode and a cathode formed on both sides of the electrolyte membrane;
A gas supply unit for supplying a fuel gas and an oxidizing gas as a power generation gas to the fuel cell;
A voltage monitoring unit for monitoring the voltage of the fuel cell and the time change of the voltage;
An abnormality monitoring unit for detecting an abnormality of the monitoring voltage monitored by the voltage monitoring unit;
With
When the fuel gas shortage occurs at the anode of the fuel cell, the abnormality monitoring unit sets a monitoring upper limit voltage that serves as a reference for detecting an abnormality when the supply amount of the fuel gas is increased. A fuel cell system characterized in that A fuel cell system,
A fuel cell having one or more fuel cells each having an anode and a cathode formed on both sides of the electrolyte membrane;
A gas supply unit for supplying a fuel gas and an oxidizing gas as a power generation gas to the fuel cell;
A voltage monitoring unit for monitoring the voltage of the fuel cell and the time change of the voltage;
An abnormality monitoring unit for detecting an abnormality of the monitoring voltage monitored by the voltage monitoring unit;
With
The abnormality monitoring unit is configured to detect an abnormality when the supply amount of the fuel gas is increased when a state in which a catalyst carrier supporting a catalyst included in a cathode of the fuel cell is oxidized is generated. A fuel cell system characterized by raising the set value of the monitoring upper limit voltage. A fuel cell system according to any one of claims 1 to 7,
If the time change of the monitoring voltage does not change from a positive state to a zero state and then changes to a negative state, the abnormality monitoring unit has failed in a component electrically connected to the fuel cell. A fuel cell system, characterized in that An abnormality detection method for a fuel cell system,
The fuel cell system includes:
A fuel cell having one or more fuel cells each having an anode and a cathode formed on both sides of the electrolyte membrane;
A gas supply unit for supplying a fuel gas and an oxidizing gas as a power generation gas to the fuel cell;
A voltage monitoring unit for monitoring the voltage of the fuel cell and the time change of the voltage;
An abnormality monitoring unit for detecting an abnormality of the monitoring voltage monitored by the voltage monitoring unit;
With
The abnormality detection method of the fuel cell system is:
An abnormality detection method for a fuel cell system, wherein when the supply of gas for power generation is stopped and then the supply is started again, a set value of a monitoring upper limit voltage that serves as a reference for detecting an abnormality is increased. An abnormality detection method for a fuel cell system,
The fuel cell system includes:
A fuel cell having one or more fuel cells each having an anode and a cathode formed on both sides of the electrolyte membrane;
A gas supply unit for supplying a fuel gas and an oxidizing gas as a power generation gas to the fuel cell;
A voltage monitoring unit for monitoring the voltage of the fuel cell and the time change of the voltage;
An abnormality monitoring unit for detecting an abnormality of the monitoring voltage monitored by the voltage monitoring unit;
With
The abnormality detection method of the fuel cell system is:
When the fuel gas shortage occurs at the anode of the fuel cell, when the supply amount of the fuel gas is increased, the set value of the monitoring upper limit voltage serving as a reference for detecting an abnormality is increased. An abnormality detection method for a fuel cell system. An abnormality detection method for a fuel cell system,
A fuel cell having one or more fuel cells each having an anode and a cathode formed on both sides of the electrolyte membrane;
A gas supply unit for supplying a fuel gas and an oxidizing gas as a power generation gas to the fuel cell;
A voltage monitoring unit for monitoring the voltage of the fuel cell and the time change of the voltage;
An abnormality monitoring unit for detecting an abnormality of the monitoring voltage monitored by the voltage monitoring unit;
With
The abnormality detection method of the fuel cell system is:
When a state in which the catalyst carrier carrying the catalyst contained in the cathode of the fuel cell is oxidized is generated, when the supply amount of the fuel gas is increased, a monitoring upper limit voltage is set as a reference for detecting an abnormality An abnormality detection method for a fuel cell system, characterized by increasing a value.

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