JP5229528B2 - Fuel cell system - Google Patents

Description

  The present invention relates to a fuel cell system.

  A fuel cell mounted on a fuel cell vehicle or the like generates electric power using a fuel gas containing hydrogen supplied to an anode and an oxidizing gas containing oxygen supplied to a cathode. Hydrogen off-gas discharged from the fuel cell is mixed and diluted with oxygen off-gas and discharged outside the vehicle in a state where the hydrogen concentration is reduced. However, when the fuel cell is operated with low power generation efficiency, not only hydrogen is discharged from the anode, but hydrogen (mainly pumping hydrogen) is discharged from the cathode, and the hydrogen exceeds the regulation range. May be discharged outside the system.

  In order to solve such a problem, a part of the oxidizing gas supplied to the cathode of the fuel cell is bypassed by using a bypass valve, and a part of the oxidizing gas is guided to the cathode off-gas flow path. A method of diluting the concentration of hydrogen (mainly pumping hydrogen) discharged from the water has been proposed (for example, see Patent Document 1).

JP 2005-294676 A

  However, if the bypass valve malfunctions, or if the bypass valve malfunctions, such as when it is stuck open due to freezing, a large amount of oxidizing gas flows to the cathode offgas flow path, and the oxidizing gas to be supplied to the fuel cell In the worst case, the system may have to be stopped due to the shortage of cell voltage and cell voltage drop.

  The present invention has been made in view of the circumstances described above, and it is possible to suppress the occurrence of a cell voltage drop or the like even when a large amount of reaction gas leaks due to an abnormality in the bypass valve. An object is to provide a possible fuel cell system.

In order to solve the above-described problem, a fuel cell system according to the present invention includes a gas supply source that supplies an oxidizing gas containing oxygen supplied to a cathode of the fuel cell to the fuel cell, and an off-gas discharged from the fuel cell. A discharge passage for discharging gas , a bypass device that bypasses the fuel cell to a part of the oxidizing gas supplied from the gas supply source, and whether or not an abnormality has occurred in the bypass device When the abnormality of the bypass device is detected by the detection means, the estimation means for estimating the amount of the oxidizing gas to be bypassed, and the gas amount estimated by the estimation means And adjusting means for adjusting the amount of oxidizing gas supplied from the gas supply source to the fuel cell.

According to this configuration, when an abnormality (for example, an open failure) occurs in a bypass device that bypasses the fuel cell and leads part of the oxidizing gas to the discharge passage, the amount of the oxidizing gas that is bypassed And the gas amount of the reaction gas supplied from the gas supply source to the fuel cell is adjusted according to the estimated gas amount. For this reason, even when a large amount of oxidizing gas is bypassed (leaked), the oxidizing gas necessary for power generation can be supplied to the fuel cell, and the occurrence of cell voltage drop or the like can be suppressed.

Here, in the above-described configuration, the bypass device includes a bypass passage and a bypass valve that controls a flow rate of a part of the oxidant gas to be bypassed, and the detection unit has an open failure in the bypass valve. A mode in which it is detected whether or not has occurred is preferable.

Further, in the above constitution, the estimating means is configured to detect the differential pressure of the oxidizing gas before and after passage of the bypass valve, senses the temperature of the oxidizing gas, and the differential pressure of the oxidizing gas has been detected A mode in which the gas amount is estimated based on temperature is further preferable.

Further, in the above configuration, the apparatus further includes a derivation unit that derives a gas amount of the oxidizing gas required for the fuel cell based on the temperature and the required current of the fuel cell, and the adjustment unit includes the estimation unit. It is preferable that the gas amount of the oxidizing gas supplied from the gas supply source to the fuel cell is adjusted based on the estimated gas amount and the gas amount derived by the deriving unit.

  As described above, according to the present invention, it is possible to suppress the occurrence of a cell voltage drop or the like even when a large amount of reaction gas leaks due to an abnormality in the bypass valve.

  Embodiments according to the present invention will be described below with reference to the drawings.

A. 1. Embodiment FIG. 1 is a diagram showing a main configuration of a fuel cell system 100 according to this embodiment. In the present embodiment, a fuel cell system mounted on a vehicle such as a fuel cell vehicle (FCHV), an electric vehicle, or a hybrid vehicle is assumed, but not only the vehicle but also various moving bodies (for example, ships, airplanes, robots, etc.) It can also be applied to stationary power sources.

The fuel cell system 100 includes a fuel gas circulation supply system and an oxidizing gas supply system.
The fuel gas circulation supply system includes a fuel gas supply source 30, a fuel gas supply path 21, a fuel cell 40, a fuel gas circulation path 22, and an anode off-gas flow path 23, and the oxidizing gas supply system includes an air compressor 60, an oxidation gas The gas supply path 11 and the cathode off-gas flow path 12 are included.

  The fuel cell 40 is a means for generating electric power from supplied reaction gas (fuel gas and oxidant gas), and has a stack structure in which a plurality of single cells including MEAs (membrane / electrode assemblies) are stacked in series. Have. Specifically, various types of fuel cells such as a solid polymer type, a phosphoric acid type, and a molten carbonate type can be used.

  The fuel gas supply source 30 is means for supplying a fuel gas such as hydrogen gas to the fuel cell 40, and is constituted by, for example, a high-pressure hydrogen tank, a hydrogen storage tank, or the like. The fuel gas supply path 21 is a gas flow path for guiding the fuel gas discharged from the fuel gas supply source 30 to the anode electrode of the fuel cell 40. The gas flow path includes a tank valve H1, hydrogen gas from upstream to downstream. Valves such as a supply valve H2 and an FC inlet valve H3 are provided. The tank valve H1, the hydrogen supply valve H2, and the FC inlet valve H3 are shut valves for supplying (or shutting off) the fuel gas to the gas flow paths 21 to 23 or the fuel cell 20, and are constituted by, for example, electromagnetic valves. Yes.

  The fuel gas circulation path 22 is a return gas flow path for recirculating unreacted fuel gas to the fuel cell 40. The gas flow path includes an FC outlet valve H4, a hydrogen pump 50, and a check valve 51 from upstream to downstream. Are arranged respectively. The low-pressure unreacted fuel gas discharged from the fuel cell 40 is appropriately pressurized by the hydrogen pump 50 and guided to the fuel gas supply path 21. The backflow of the fuel gas from the fuel gas supply path 21 to the fuel gas circulation path 22 is suppressed by the check valve 51.

  The anode off gas passage 23 is a gas passage for exhausting the anode off gas containing the hydrogen off gas discharged from the fuel cell 40 out of the system, and a purge valve H5 is disposed in the gas passage.

  The air compressor (gas supply source) 60 supplies oxygen (oxidizing gas) taken from outside air to the cathode electrode of the fuel cell 40 via an air filter (not shown). Cathode off-gas is discharged from the cathode of the fuel cell 40. The cathode off gas includes pumping hydrogen generated on the cathode side in addition to oxygen off gas after being subjected to the cell reaction of the fuel cell 40 (details will be described later). This cathode off gas is in a highly moist state because it contains moisture generated by the cell reaction of the fuel cell 40.

  The humidification module 70 exchanges moisture between the low-humidity oxidizing gas flowing through the oxidizing gas supply path 11 and the high-humidity cathode offgas flowing through the cathode offgas flow path 12, and the oxidation supplied to the fuel cell 40. Humidify the gas moderately. The back pressure of the oxidizing gas supplied to the fuel cell 40 is regulated by a pressure regulating valve A1 disposed near the cathode outlet of the cathode offgas passage 12 under the control of the control device 160. The oxidizing gas supply path 11 from the air compressor 60 to the humidification module 70 is provided with a pressure sensor P1 for detecting the pressure of the supplied oxidizing gas and a temperature sensor T1 for detecting the temperature of the oxidizing gas. .

  Here, the oxidizing gas supply path 11 from the air compressor 60 to the humidification module 70 and the cathode offgas flow path 12 from the humidification module 70 to the diluter 80 are connected by a bypass valve B1. The bypass valve (bypass device) B1 and the bypass passage (bypass device) 31 are means for guiding part of the oxidizing gas flowing through the oxidizing gas supply passage 11 to the cathode off-gas passage (discharge passage) 12 by bypassing the fuel cell 40. Yes, the amount of oxidizing gas (hereinafter referred to as bypass air) bypassed by the control device (adjusting means) 160 is adjusted. In the bypass passage 31, a pressure sensor P2 for detecting the pressure (primary pressure) of the bypass air before passing through the bypass valve B1, and the pressure (secondary pressure) of the bypass air after passing through the bypass valve B1 are detected. A pressure sensor P3 is provided. Further, a valve body position detection sensor (detection means) 180 that detects the valve body position of the bypass valve B1 under the control of the control device (detection means) 160 is provided in the vicinity of the bypass valve B1.

  The diluter 80 dilutes the hydrogen gas discharge concentration so that it falls within a preset concentration range (such as a range determined based on environmental standards). The diluter 80 communicates with the downstream side of the cathode offgas channel 12 and the downstream side of the anode offgas channel 23, and mixes and dilutes hydrogen offgas, pumping hydrogen, oxygen offgas, and bypass air and exhausts them outside the system.

Part of the DC power generated by the fuel cell 40 is stepped up / down by the DC / DC converter 130 and charged in the battery 140.
The battery 140 is a chargeable / dischargeable secondary battery, and is composed of various types of secondary batteries (for example, a nickel metal hydride battery). Of course, instead of the battery 140, a chargeable / dischargeable capacitor other than the secondary battery, for example, a capacitor may be used.

The traction inverter 110 and the auxiliary inverter 120 are pulse width modulation type PWM inverters, and convert DC power output from the fuel cell 40 or the battery 140 into three-phase AC power in accordance with a given control command, thereby obtaining a traction motor. Supply to M3 and auxiliary motor M4.
The traction motor M3 is a motor for driving the wheels 150L and 150R, and the auxiliary motor M4 is a motor for driving various auxiliary machines. The auxiliary motor M4 is a generic term for a motor M1 that drives the hydrogen circulation pump 50, a motor M2 that drives the air compressor 60, and the like.

  The control device 160 includes a CPU, a ROM, a RAM, and the like, and centrally controls each part of the system based on each sensor signal that is input. Specifically, an accelerator pedal sensor S1 that detects the accelerator pedal opening, an SOC sensor S2 that detects a state of charge (SOC) of the battery 140, and a T / C motor rotational speed that detects the rotational speed of the traction motor M3. In addition to the detection sensor S3, the voltage sensor S4 for detecting the output voltage of the fuel cell 40, the current sensor S5 for detecting the output current, each sensor signal input from the temperature sensors T1, T2, the pressure sensors P1, P2, P3, etc. Based on this, the output pulse width of the inverters 110 and 120 is controlled.

  In addition, when it is necessary to warm up the fuel cell 40, such as at a low temperature start, the control device 160 uses the maps mp1 to mp5 stored in the memory 170 to perform an operation with low power generation efficiency.

  FIG. 2 is a diagram showing the relationship between the output current (FC current) and the output voltage (FC voltage) of the fuel cell, and shows a case where an operation with high power generation efficiency (normal operation) is performed, indicated by a solid line. A case where an operation with low power generation efficiency (low efficiency operation) is performed by narrowing down is shown by a dotted line. The horizontal axis represents the FC current, and the vertical axis represents the FC voltage.

  Normally, when operating the fuel cell 40, the fuel cell 40 is operated in a state where the air stoichiometric ratio is set to 1.0 or more (theoretical value) so that high power generation efficiency can be obtained while suppressing power loss (see FIG. (See solid line part 2). Here, the air stoichiometric ratio means an excess ratio of the actual air supply amount with respect to the theoretical air supply amount necessary for generating the FC current.

  On the other hand, when the fuel cell 40 is warmed up, the fuel cell 40 is set with the air stoichiometric ratio set at around 1.0 (theoretical value) in order to increase the power loss and raise the temperature of the fuel cell 40. (See the dotted line portion in FIG. 2). When the air stoichiometric ratio is set to a low value, the power loss (that is, the heat loss) out of the energy that can be extracted by the reaction between hydrogen and oxygen is positively increased. Pumping hydrogen is generated at the cathode.

FIG. 3 is a diagram for explaining the generation mechanism of pumping hydrogen, FIG. 3A is a diagram showing a battery reaction during normal operation, and FIG. 3B is a diagram showing a battery reaction during low-efficiency operation.
Each cell 4 includes an electrolyte membrane 4a, and an anode electrode and a cathode electrode that sandwich the electrolyte membrane 4a. A fuel gas containing hydrogen (H ₂ ) is supplied to the anode, and an oxidizing gas containing oxygen (O ₂ ) is supplied to the cathode. When fuel gas is supplied to the anode, the reaction of the following formula (A) proceeds and hydrogen is separated from hydrogen ions and electrons. Hydrogen ions generated at the anode permeate the electrolyte membrane 4a and move to the cathode, while electrons move from the anode to the cathode through an external circuit.

Here, when the supply of the oxidizing gas to the cathode is sufficient (air stoichiometric ratio ≧ 1.0), the following formula (B) proceeds to generate water from oxygen, hydrogen ions, and electrons (see FIG. 3A). ). On the other hand, when the supply of oxidizing gas to the cathode is insufficient (air stoichiometric ratio <1.0), the following formula (C) proceeds according to the amount of oxidizing gas that is insufficient, and hydrogen ions and electrons are recombined. Thus, hydrogen is generated (see FIG. 3B). The produced hydrogen is discharged from the cathode together with the oxygen off gas. Note that hydrogen generated at the cathode by recombination of dissociated hydrogen ions and electrons, that is, the anode gas generated at the cathode is called pumping hydrogen.
Anode: H ₂ → 2H ⁺ + 2e ⁻ (A)
Cathode: 2H ⁺ + 2e ⁻ + (1/2) O ₂ → H ₂ O (B)
Cathode: 2H ⁺ + 2e ⁻ → H ₂ (C)

  Thus, since the pumping hydrogen is contained in the cathode off gas when the supply of the oxidizing gas to the cathode is insufficient, the valve opening degree of the bypass valve B1 is adjusted in accordance with the amount of pumping hydrogen contained in the cathode off gas. By adjusting the flow rate of the bypass air in this manner, it is possible to dilute the exhaust hydrogen concentration so as to be within an appropriate range while supplying the oxidizing gas necessary for power generation to the cathode electrode of the fuel cell 40.

  However, if the bypass valve B1 is always open in a low temperature environment, the valve body freezes and becomes a cause of an open failure. When such an open failure occurs, a large amount of the oxidizing gas supplied from the air compressor 60 is bypassed, and the oxidizing gas necessary for power generation is not supplied to the fuel cell 40 (in other words, an oxidizing gas deficient state occurs. ), And the cell voltage drops.

  Therefore, in the present embodiment, even if an abnormality such as an open failure occurs in the bypass valve B1 as described above, the air compressor is used so that the oxidizing gas (FC required air) necessary for power generation is supplied to the fuel cell 40. Adjust the amount of oxidizing gas (air supply air) to be supplied. Hereinafter, the operation of the fuel cell system 100 when the system is started will be described.

FIG. 4 is a flowchart showing the operation of the fuel cell system 100 when the system is started.
When the control device 140 receives an operation start command for the fuel cell system 100 by, for example, turning on an ignition switch by a vehicle driver (step S100), whether or not an abnormality such as an open failure has occurred in the bypass valve B1. Is determined (step S200). More specifically, the control device (detection means) 140 controls the valve body position detected by the valve body position detection sensor (detection means) 180 in spite of performing control for changing the valve opening degree of the bypass valve B1. If not changed, it is determined that an abnormality such as an open failure has occurred in the bypass valve B1 (step S200; YES), and fail-safe processing is executed (step S300).

  On the other hand, when the valve body position is changed according to the control for changing the valve opening degree of the bypass valve B1, the control device 140 determines that an abnormality such as an open failure has not occurred in the bypass valve B1 ( Step S200; NO), normal start processing is executed (step S400).

<Fail-safe treatment>
FIG. 5 is a flowchart showing the fail-safe process.
When an abnormality such as an open failure has occurred in the bypass valve B1, the control device (estimating means) 140 has a flow coefficient α, a differential pressure ΔP (Pa), a throttle diameter d (m), and a fluid density γ ( kg / m3), the bypass air flow rate QBP is estimated (step S310). The flow coefficient α and the diameter d of the throttle are values inherent to the valve, and the density γ is derived as a function of temperature and pressure.

The bypass air flow rate QBP can be derived as a function of temperature and pressure. Specifically, the control device (estimating means) 140 derives the differential pressure ΔP from the primary pressure and the secondary pressure of the bypass air detected by the pressure sensors P2 and P3, and the oxidation detected by the temperature sensor T1. Find the gas temperature. The control device 140 derives the bypass air flow rate QBP using these values.

When the control device (derivation means) 140 estimates the bypass air flow rate QBP as described above, I: required current (A), F: Faraday constant, Ncell: number of FC stack cells, S: FC request using air stoichiometric ratio An air flow rate (FC required air flow rate) QFC is derived (step S320). The Faraday constant F and the FC stack cell number Ncell are constant values, and the air stoichiometric ratio S is derived as a function of the required current and FC temperature.

The FC required air flow rate QFC can be derived as a function of the required current I and the FC temperature. Specifically, the control device 140 derives a required current I corresponding to the generated power using a map (not shown), and obtains the FC temperature detected by the temperature sensor T2. The control device 140 derives the FC required air flow rate QFC using these values.

Control device 140, the estimated boss was bypassed air flow rate QBP, adds the FC required air flow QFC which issued guide (i.e. plus) by, deriving the air air flow rate (air supply air flow rate) QAIR (step S330 ; See formula (3) below).
QAIR = QBP + QFC

The control device (adjusting means) 140 controls the operation of the air compressor 60 so as to obtain the derived air supply air flow rate Q _AIR (step S340), and ends the process.

<Normal start processing>
FIG. 6 is a flowchart showing normal start processing.
The control device 140 determines whether or not the FC temperature detected by the temperature sensor T2 is lower than a reference temperature set in a memory (not shown) (step S410). Here, the reference temperature is a reference temperature (for example, 0 ° C.) for determining whether or not the low-efficiency operation should be performed when the system is started. The reference temperature may be set in advance at the time of manufacture and shipment, but may be set / changed as appropriate by operating a button.

  When detecting that the detected FC temperature exceeds the reference temperature, the control device 140 starts normal operation (step S420) and ends the process.

  On the other hand, after detecting that the detected FC temperature is lower than the reference temperature, the control device 140 determines the target low-efficiency operation point (It, Vt) to start the low-efficiency operation ( 2), the low efficiency stoichiometric ratio map mp1 stored in the memory 170 is referred to. The low-efficiency operation stoichiometric ratio map mp1 is used to determine the air stoichiometric ratio from the FC current command value It and the FC voltage command value Vt, and is created based on values obtained through experiments or the like. The control device 140 determines the air stoichiometric ratio Ra at the operating point using the determined FC current It, FC voltage Vt, and low efficiency operating stoichiometric ratio map mp1 (step S430).

  When determining the air stoichiometric ratio Ra, the control device 140 refers to the pumping hydrogen amount map mp2 and the purge hydrogen amount map mp3 stored in the memory 170. The pumping hydrogen amount map mp2 is for estimating the generation amount of pumping hydrogen (pumping hydrogen amount) from the FC current command value It, the determined air stoichiometric ratio Ra, and the temperature of the fuel cell 40 detected by the temperature sensor S6. It is created based on values obtained by experiments. The purge hydrogen amount map mp3 is a map for estimating the discharge amount of the anode off gas including the hydrogen off gas (purge hydrogen amount) from the FC current.

The control device 140 estimates the pumping hydrogen amount Ap1 using the determined FC current command value It, the air stoichiometric ratio Ra, the temperature of the fuel cell 40, and the pumping hydrogen amount map mp2, while determining the determined FC current command value It, purge The purge hydrogen amount Ap2 is estimated using the hydrogen amount map mp3, and the total exhaust hydrogen amount At at the target low-efficiency operating point (It, Vt) is obtained (step S440; see the following formula (4)).
At = Ap1 + Ap2 (4)

When determining the total exhaust hydrogen amount At, the control device 140 derives an FC required air flow rate, an air scavenging amount command value, and a bypass air flow rate that are necessary to make the exhaust hydrogen concentration equal to or less than the reference value (step S450). Specifically, first, an air flow rate required for the fuel cell 40 (FC required air flow rate) An is obtained using the following formula (5).
An = It * {400 * 22.4 * 60 / (4 * 96485)} * 100/21 (5)

Next, the control device 140 obtains an air flow rate (FC consumed air flow rate) Ac consumed by the fuel cell 40 using the following equation (6), and calculates an exhaust hydrogen concentration using the following equation (7). An air flow rate (total air flow rate) Ad necessary for dilution below the reference value is obtained.
Ac = It * 400 * 22.4 * 60 / (4 * 96485) (6)
Ad = (At * 100 / Dt) + Ac (7)
Dt: exhaust hydrogen target concentration (%)

Further, the control device 140 compares the value obtained by adding the bypass minimum air flow rate Abl to the FC required air flow rate An and the total air flow rate Ad, and sets the larger one as the air supply amount command value Asp of the air compressor 60 ( (See the following formula (8)). Then, the bypass air flow rate Abp is obtained by substituting the set air supply amount command value Asp and the FC required air flow rate An into the following equation (9). The bypass minimum air flow rate Abl represents the minimum value of the air flow rate that should flow through the bypass line 31 during low-efficiency operation.
Asp = MAX {(An + Abl), (Ad)} (8)
Abp = Asp-An (9)

  When determining the FC required air flow rate An and the bypass air flow rate Abp, the control device 140 refers to the air pressure regulating valve opening degree map mp4 and the bypass valve opening degree map mp5. The air pressure adjustment valve opening degree map mp4 is a map for determining the valve opening degree of the air pressure adjustment valve A1 from the FC required air flow rate An and the bypass air flow rate Abp, and the bypass valve opening degree map mp5 is the FC required air flow rate An. And a map for determining the valve opening degree of the bypass valve B1 from the bypass air flow rate Abp.

  The control device 140 uses the FC required air flow rate An, the bypass air flow rate Abp, the air pressure adjustment valve opening degree map mp4, and the bypass valve opening degree map mp5 to open the air pressure adjustment valve A1 and the valve opening degree of the bypass valve B1. Is adjusted (step S460). At this time, the valve opening degree of the air pressure regulating valve A1 is corrected by a PID correction term generated from the deviation between the measured value of the FC current detected by the ammeter S5 and the target value.

  Further, when the control device 140 controls the driving of the air compressor 60 in accordance with the set air supply amount command value As (step S470), the control device 140 proceeds to step S480 and determines whether or not the low efficiency operation should be terminated (that is, the fuel cell 40). It is determined whether or not the warm-up operation should be terminated. Here, if the temperature of the fuel cell 40 is equal to or higher than a preset reference temperature, the low-efficiency operation is terminated. If the temperature is lower than the reference temperature, the process returns to step S430 and the above-described processing is continued. Of course, the present invention is not limited to this, and it may be determined whether or not the low-efficiency operation should be terminated based on the heat generation amount, the operation time of the low-efficiency operation, or the like.

  As described above, according to the present embodiment, when an abnormality such as an open failure occurs in the bypass valve B1, fail-safe processing is executed, and oxidizing gas necessary for power generation is supplied to the fuel cell 40. As described above, the amount of oxidizing gas supplied from the air compressor 60 is adjusted. Thereby, even when a large amount of oxidizing gas leaks, the oxidizing gas necessary for power generation is supplied to the fuel cell, so that it is possible to suppress the occurrence of cell voltage drop or the like.

B. Modified Example (1) In the above-described embodiment, the case where the bypass valve B1 has an open failure due to freezing and fixing has been described as an example. However, the bypass valve B1 is abnormal (open failure or closed failure) due to disconnection or deformation of the valve body, for example. ) Occurs in the same manner. Further, not only the abnormality of the bypass valve B1, but also the case where the oxidizing gas leaks inside the fuel cell 40 or the oxidizing gas leaks due to disconnection of the piping of the oxidizing gas supply path 11 can be similarly applied. .

(2) In the above-described embodiment, as an aspect of the low-efficiency operation, the case where the fuel cell is caused to generate power in a state where the oxidizing gas supplied to the cathode is insufficient has been described. The fuel cell may generate power in a state where the fuel gas supplied to the anode is insufficient.

(3) In the present embodiment, the exhaust hydrogen concentration is reduced by bypassing the fuel cell and guiding the part of the dilution gas (oxidizing gas) flowing through the gas supply path to the discharge passage. A supply means may be provided separately, and the exhaust gas concentration may be reduced by introducing dilution gas from the gas supply means to the discharge passage.

(4) In this embodiment, the case of performing the low efficiency operation at the time of starting the system is exemplified. However, for example, the low efficiency operation is performed when the system required power becomes a predetermined value or less or when there is a system stop instruction. May be.

(5) In this embodiment, the differential pressure ΔP is derived from the primary pressure and the secondary pressure of the bypass air detected by the pressure sensors P2 and P3. However, the pressure of the bypass air detected by the pressure sensor P3 is calculated. The pressure sensor P3 may be omitted assuming that it is atmospheric pressure (that is, substituting with atmospheric pressure). Furthermore, it is also possible to consider that the respective pressures detected by the pressure sensors P1 and P2 are equal and use only one of the pressure sensors (for example, the pressure sensor P2).

It is a figure which shows the principal part structure of the fuel cell system which concerns on this embodiment. It is a figure which shows the relationship between FC electric current and FC voltage which concern on the same embodiment. It is a figure for demonstrating the generation | occurrence | production mechanism of pumping hydrogen concerning the embodiment. It is a figure for demonstrating the generation | occurrence | production mechanism of pumping hydrogen concerning the embodiment. It is a flowchart which shows the operation | movement at the time of the system start which concerns on the same embodiment. It is a flowchart which shows the fail safe process which concerns on the same embodiment. It is a flowchart which shows the normal start process which concerns on the same embodiment.

Explanation of symbols

30 ... Fuel gas supply source, 40 ... Fuel cell, 50 ... Hydrogen circulation pump, 60 ... Air compressor, 70 ... Humidification module, 80 ... Diluter, 110 ... Traction Inverter, 120 ... Auxiliary machine inverter, 130 ... DC / DC converter, 140 ... Battery, 150L, 150R ... Wheel, 160 ... Control device, 180 ... Valve body position detection sensor, H1 ... tank valve, H2 ... hydrogen supply valve, H3 ... FC inlet valve, H4 ... FC outlet valve, H5 ... purge valve, 51 ... check valve, A1 ... pressure Regulating valve, B1 ... Bypass valve, 11 ... Oxidizing gas supply passage, 12 ... Cathode off gas passage, S1 ... Accelerator pedal sensor, S2 ... SOC sensor, S3 ... T C motor rotation speed detection sensor, S4 ... voltage sensor, S5 ... current sensor, T1, T2 ... temperature sensor, P1, P2, P3 ... pressure sensor, mp1 ... low efficiency operation stoichiometric ratio Map, mp2 ... pumping hydrogen amount map, mp3 ... purge hydrogen amount map, mp4 ... air pressure regulating valve opening map, mp5 ... bypass valve opening map, 100 ... fuel cell system.

Claims (4)

A gas supply source for supplying an oxidizing gas containing oxygen to the fuel cell;
A discharge passage for discharging off-gas discharged from the fuel cell;
A bypass device that bypasses the fuel cell and guides part of the oxidizing gas supplied from the gas supply source to the discharge passage;
Detecting means for detecting whether or not an abnormality has occurred in the bypass device;
When an abnormality of the bypass device is detected by the detection means, an estimation means for estimating a gas amount of the oxidizing gas to be bypassed;
A fuel cell system comprising: adjusting means for adjusting the amount of oxidizing gas supplied from the gas supply source to the fuel cell in accordance with the gas amount estimated by the estimating means. The bypass device includes a bypass passage and a bypass valve that controls a flow rate of a part of the oxidizing gas to be bypassed,
The fuel cell system according to claim 1, wherein the detection unit detects whether an open failure has occurred in the bypass valve. It said estimating means is configured to detect the differential pressure of the oxidizing gas before and after passage of the bypass valve, senses the temperature of the oxidizing gas, estimate the gas amount based on the differential pressure and the temperature of the oxidation gas detected The fuel cell system according to claim 2, wherein: A deriving means for deriving the amount of oxidizing gas required for the fuel cell based on the temperature and the required current of the fuel cell;
The adjusting means adjusts the gas amount of the oxidizing gas supplied from the gas supply source to the fuel cell based on the gas amount estimated by the estimating means and the gas amount derived by the deriving means. The fuel cell system according to claim 3, wherein

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