Fuel cell system and control method for fuel cell system

Abstract

To provide a fuel cell system capable of detecting the presence / absence of a surge failed state of an air compressor in the case of emergency stop.SOLUTION: When an abnormal signal of a fuel cell system 10 is acquired (when the need of emergency stop of a fuel cell stack 12 occurs), a control device 26 opens a bypass valve 120 while continuing supply of power from a power source 244 to an air compressor 112. After the lapse of a predetermined time from the opening of the bypass valve 120, the supply of power from the power source 244 to the air compressor 112 is stopped. Before stopping the supply of power to the air compressor 112, the control device 26 is capable of detecting the presence / absence of a surge failed state of the air compressor 112.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a fuel cell system and a method for controlling a fuel cell system. [Background technology]

[0002] In recent years, research and development into fuel cells has been conducted to contribute to energy efficiency in order to ensure that more people have access to affordable, reliable, sustainable and advanced energy.

[0003] A power generation system equipped with a fuel cell stack is called a fuel cell system. A fuel cell stack is equipped with multiple power generation cells. Each power generation cell generates electricity through an electrochemical reaction between fuel gas (hydrogen-containing gas) and oxidant gas (oxygen-containing gas) supplied from an air compressor.

[0004] For example, Patent Document 1 discloses a technique for eliminating surging in an air compressor by reducing the rotation speed of a motor that constitutes the air compressor (paragraph

[0057] of Patent Document 1).

[0005] Patent Document 2 discloses a technique for eliminating surging when surging occurs in an air compressor and there is no load demand by increasing the opening of a bypass valve that bypasses the supply of oxidant gas to the fuel cell stack (paragraph

[0026] of Patent Document 2). [Prior art documents] [Patent documents]

[0006] [Patent Document 1] JP 2009-76243 A [Patent Document 2] JP 2019-133830 A Summary of the Invention [Problem to be solved by the invention]

[0007] A turbo air compressor may be used as an air compressor for a fuel cell system. In a turbo air compressor, a supercharger is provided at both ends of a rotor shaft having an air bearing and an impeller at both ends, and the pressure and flow rate are increased by connecting the supercharger with piping. In this turbo air compressor, high voltage power supplied from a high voltage battery via a high voltage relay is converted into a three-phase AC current through an inverter. When this three-phase AC current is supplied to a three-phase stator coil, the rotor shaft rotates, and the rotor shaft is lifted by the air bearing. In this way, the air compressor is driven through an inverter that converts a high voltage DC current into a three-phase AC current.

[0008] However, when the fuel cell system receives a large shock, it is necessary to stop the air compressor in order to stop the fuel cell system. Conventionally, in the event of such an emergency stop, the high voltage relay is immediately turned off to immediately cut off the supply of high voltage DC power applied to the inverter that drives the air compressor.

[0009] However, if the supply of high-voltage power applied to the inverter that drives the air compressor is immediately cut off during an emergency stop, there is a problem that even if a surge fault occurs in the air compressor, this surge fault state cannot be noticed.

[0010] The present invention aims to solve the above-mentioned problems. [Means for solving the problem]

[0011] A first invention is a fuel cell system comprising: a fuel cell stack having a plurality of power generating cells that generate power from an oxidant gas and a fuel gas; an air compressor that supplies the oxidant gas to the fuel cell stack via an oxidant gas supply path; a power source capable of supplying power to the air compressor; a bypass valve provided in a bypass flow path connecting the oxidant gas supply path and an oxidant gas discharge path of the fuel cell stack; and a control device that controls the fuel cell stack, the air compressor, the power source, and the bypass valve, wherein the control device comprises an acquisition unit that acquires an abnormality signal that requires an emergency shutdown of the fuel cell system; a control unit that, when the acquisition unit acquires the abnormality signal, opens the bypass valve while continuing the supply of power to the air compressor, and stops the supply of power to the air compressor after the bypass valve has been opened; and a determination unit that, when the abnormality signal is acquired, determines whether or not the air compressor has experienced a surge fault while continuing the supply of power.

[0012] A second invention is a control method for a fuel cell system including a fuel cell stack having a plurality of power generating cells that generate power using an oxidant gas and a fuel gas, an air compressor that supplies the oxidant gas to the fuel cell stack via an oxidant gas supply path, a power source that supplies power to the air compressor, a bypass valve provided in a bypass flow path connecting the oxidant gas supply path and an oxidant gas discharge path of the fuel cell stack, and a control device that controls the fuel cell stack, the air compressor, the power source, and the bypass valve, wherein the control device receives an abnormality signal that requires an emergency shutdown of the fuel cell system, and, when the control device receives the abnormality signal, opens the bypass valve while continuing to supply the power from the power source to the air compressor, and stops the supply of power to the air compressor after the bypass valve has been opened, and, when the control device receives the abnormality signal, determines whether or not there is a surge fault in the air compressor while continuing to supply power. Effect of the Invention

[0013] According to the present invention, the presence or absence of a surge fault state in the air compressor can be detected during an emergency stop. [Brief description of the drawings]

[0014] [Figure 1] FIG. 1 is a schematic diagram of a fuel cell vehicle equipped with a fuel cell system according to an embodiment. [Diagram 2] FIG. 2 is a schematic diagram of a turbo air compressor equipped with an air bearing mechanism. [Diagram 3] FIG. 3 is an explanatory diagram of a surge determination map for an air compressor. [Figure 4] FIG. 4 is a flowchart illustrating the detection control operation for a surge failure state of the air compressor when the fuel cell system is stopped in an emergency. [Diagram 5] FIG. 5 is a time chart illustrating an example of the operation of the embodiment described with reference to the flowchart of FIG. [Figure 6] FIG. 6 is a time chart of a comparative example. [Figure 7] FIG. 7 is a flowchart of a modified example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] [Configuration of fuel cell system 10] FIG. 1 is a schematic diagram of a fuel cell vehicle 11 equipped with a fuel cell system 10 according to an embodiment. The fuel cell system 10 can be installed in ships, aircraft, robots, and the like, in addition to vehicles. The fuel cell system 10 can also be used as a power source in facilities, homes, and the like. In the fuel cell system 10, a fuel gas and an oxidant gas are used as reactant gases. The fuel gas is a hydrogen-containing gas. The oxidant gas is an oxygen-containing gas such as air. Each of the fuel gas and the oxidant gas is supplied to a fuel cell stack 12 and subjected to an electrochemical reaction. In this specification, the fuel gas discharged from the fuel cell stack 12 without being subjected to an electrochemical reaction is also referred to as a fuel off-gas. In this specification, the oxidant gas discharged from the fuel cell stack 12 without being subjected to an electrochemical reaction is also referred to as an oxidant off-gas.

[0016] The fuel cell system 10 includes a fuel cell stack 12, a tank 14, an anode system 16, a cathode system 18, a cooling system 20, a load 21, and a power supply system 27. The fuel cell system 10 also includes a controller .

[0017] The fuel cell stack 12 includes a positive electrode terminal 23a and a negative electrode terminal 23b. Electric power generated by the fuel cell stack 12 is supplied to the load 21 and the power supply system 27 via the positive electrode terminal 23a and the negative electrode terminal 23b. The tank 14 is filled with high-pressure fuel gas. The fuel cell stack 12 includes a fuel gas supply port 22a that supplies fuel gas to the inside of the fuel cell stack 12, and a fuel gas discharge port 22b that discharges fuel off-gas from the inside of the fuel cell stack 12. The fuel cell stack 12 includes an oxidant gas supply port 22c that supplies oxidant gas to the inside of the fuel cell stack 12, and an oxidant gas discharge port 22d that discharges oxidant off-gas from the inside of the fuel cell stack 12. The fuel cell stack 12 includes a cooling medium supply port 22e that supplies a cooling medium to the inside of the fuel cell stack 12, and a cooling medium discharge port 22f that discharges the cooling medium from the inside of the fuel cell stack 12.

[0018] The anode system 16 includes a fuel gas supply channel 84, a fuel gas discharge channel 86, a circulation channel 88, and a drain channel 90. The anode system 16 includes an injector 94, an ejector 96, a gas-liquid separator 98, and a drain valve 100. The fuel gas supply channel 84 is connected to the discharge port of the tank 14 and the fuel gas supply port 22a of the fuel cell stack 12. The fuel gas supply channel 84 includes an injector 94 and an ejector 96. The inlet port of the ejector 96 is connected to the discharge port of the injector 94, and the discharge port of the ejector 96 is connected to the fuel gas supply port 22a. The ejector 96 is disposed between the injector 94 and the fuel gas supply port 22a. The fuel gas discharge channel 86 is connected to the fuel gas discharge port 22b of the fuel cell stack 12 and the supply port of the gas-liquid separator 98. The circulation path 88 is connected to an exhaust port of the gas-liquid separator 98 and a suction port of the ejector 96. The drain path 90 is connected to a drain port of the gas-liquid separator 98 and a discharge path 109. The discharge path 109 communicates with the atmosphere through a discharge port 109p provided in the fuel cell vehicle 11. A drain valve 100 is provided in the drain path 90.

[0019] The cathode system 18 includes an oxidant gas supply channel 106, an oxidant gas discharge channel 108 (discharge channel), and a bypass flow path 110. The cathode system 18 includes an air cleaner 105, an air compressor 112 (oxidant gas supplier), a humidifier 114, an inlet seal valve 116, an outlet seal valve 118 which is a back pressure valve, and a bypass valve 120. The oxidant gas supply channel 106 is connected to an air intake port 106p provided in the fuel cell vehicle 11 and an oxidant gas supply port 22c of the fuel cell stack 12. The oxidant gas supply channel 106 includes the air cleaner 105, a flow sensor 107, the air compressor 112, the inlet seal valve 116, and a humidifier supply channel 114A of the humidifier 114. A portion of the oxidizing gas supply channel 106 that is disposed upstream of the humidifier 114 is referred to as the oxidizing gas supply channel 106A. A portion of the oxidizing gas supply channel 106 that is disposed downstream of the humidifier 114 is referred to as the oxidizing gas supply channel 106B. The inlet seal valve 116 is disposed closer to the humidifier 114 than the air compressor 112. A flow sensor 107 is attached to the oxidizing gas supply channel 106A upstream of the air compressor 112. A pressure sensor 268 is attached to the oxidizing gas supply channel 106A downstream of the air compressor 112. The flow sensor 107 detects the flow rate Qo of the oxidizing gas flowing through the air compressor 112. The pressure sensor 268 detects the pressure Pc of the discharge port 302 of the air compressor 112 (the outlet pressure of the air compressor 112).

[0020] FIG. 2 is a schematic diagram of a turbo air compressor 112 equipped with an air bearing mechanism. The air compressor 112 has a rotor shaft 274, and an impeller 276 is fixed to the rotor shaft 274 or is provided so as to rotate integrally with the rotor shaft 274. A plurality of magnets are embedded in the cylindrical side surface of the rotor shaft 274 in the axial direction. U-phase, V-phase, and W-phase stator coils 272 are attached to the casing of the air compressor 112. An air bearing 292 through which the rotor shaft 274 is inserted is attached to the casing of the air compressor 112. A flow path for oxidant gas is attached to the casing of the air compressor 112, and a supercharger 294 including an impeller 276 is provided. When the impeller 276 rotates with the rotation of the rotor shaft 274, the air bearing 292 levitates the rotor shaft 274 by compressed air at a predetermined rotation speed or higher. Air is drawn in through an intake port 300 of the air compressor 112, which communicates with the oxidizing gas supply channel 106A, and is supercharged (compressed and compressed) by the supercharger 294. The compressed and compressed air, i.e., the oxidizing gas, is discharged from a discharge port 302 to the oxidizing gas supply channel 106A.

[0021] Returning to FIG. 1, the oxidizing gas discharge channel 108 is connected to the oxidizing gas discharge port 22d of the fuel cell stack 12 and a discharge channel 109. The oxidizing gas discharge channel 108 is provided with a humidifier discharge channel 114B of the humidifier 114 and an outlet seal valve 118. A portion of the oxidizing gas discharge channel 108 that is disposed upstream of the humidifier 114 is referred to as an oxidizing gas discharge channel 108A. A portion of the oxidizing gas discharge channel 108 that is disposed downstream of the humidifier 114 is referred to as an oxidizing gas discharge channel 108B.

[0022] A hydrogen concentration sensor 111 is attached to the oxidizing gas discharge path 108A. The hydrogen concentration sensor 111 is attached near the oxidizing gas discharge port 22d. The hydrogen concentration sensor 111 detects the hydrogen concentration Dh in the oxidizing off-gas.

[0023] The bypass flow passage 110 is connected to an oxidizing gas supply passage 106A between the air compressor 112 and the inlet sealing valve 116, and to an oxidizing gas discharge passage 108B downstream of the outlet sealing valve 118. The bypass flow passage 110 is provided with a bypass valve 120.

[0024] The cooling system 20 includes a cooling medium supply path 122 and a cooling medium discharge path 124. The cooling system 20 includes a pump 126 and a radiator 128. The cooling medium supply path 122 is connected to a fluid discharge port of the radiator 128 and a cooling medium supply port 22e of the fuel cell stack 12. The cooling medium supply path 122 includes a pump 126. The cooling medium discharge path 124 is connected to a cooling medium discharge port 22f of the fuel cell stack 12 and a fluid supply port of the radiator 128. A temperature sensor 130 is attached to the cooling medium discharge path 124. The temperature sensor 130 detects the temperature of the cooling medium flowing through the cooling medium discharge path 124. The temperature of the cooling medium flowing through the cooling medium discharge path 124 corresponds to the temperature inside the fuel cell stack 12 (stack temperature).

[0025] The fuel cell stack 12 is formed by stacking a plurality of power generation cells 24. The power generation cell 24 includes a membrane electrode assembly 32 and separators 28, 30 that sandwich the membrane electrode assembly 32. The membrane electrode assembly 32 includes an MEA (Membrane Electrode Assembly) 36, which is, for example, a thin film (solid polymer electrolyte membrane) of perfluorosulfonic acid containing moisture, and a cathode electrode 40 and an anode electrode 38 that sandwich the MEA 36. The cathode electrode 40 and the anode electrode 38 have a gas diffusion layer (not shown) made of carbon paper or the like. An electrode catalyst layer (not shown) is formed by uniformly applying porous carbon particles having a platinum alloy supported on the surface of the gas diffusion layer. The electrode catalyst layer is formed on both sides of the MEA 36.

[0026] A cathode flow path (oxidant gas flow path) 50 that communicates with the oxidant gas supply port 22c and the oxidant gas discharge port 22d is formed on the surface of one of the separators 28 facing the membrane electrode assembly 32. The pressure of the oxidant gas flowing through the cathode flow path 50 is controlled by the control device 26 adjusting the opening of the outlet seal valve 118.

[0027] An anode flow path (fuel gas flow path) 66 that communicates the fuel gas supply port 22a and the fuel gas discharge port 22b is formed on the surface of the other separator 30 facing the membrane electrode assembly 32. When fuel gas (hydrogen) is supplied to the anode electrode 38, hydrogen ions are generated from hydrogen molecules by an electrode reaction caused by a catalyst, and the hydrogen ions permeate the MEA 36 and move to the cathode electrode 40, while electrons are released from the hydrogen molecules. The electrons released from the hydrogen molecules move from the separator 30 and the negative electrode terminal 23b through the load 21, via the positive electrode terminal 23a and the separator 28, to the cathode electrode 40. At the cathode electrode 40, the hydrogen ions and the electrons react with oxygen contained in the supplied oxidant gas by the action of a catalyst to generate water.

[0028] Each power generating cell 24 is provided with a cell voltage sensor 25 for detecting a cell voltage Vcell, which is the inter-terminal voltage of one power generating cell 24 (single cell). The load 21 includes a motor 246 and an air compressor 112 as high voltage loads.

[0029] The power supply system 27 includes a power supply 248 which is a low-voltage power supply that generates a low voltage Vl, and a power supply 244 which is a high-voltage power supply that generates a high voltage Vh. A lead-acid battery is used as the power supply 248 here. A lithium-ion secondary battery or the like may be used instead of the lead-acid battery. A lithium-ion secondary battery is used as the power supply 244 here. A capacitor or the like may be used instead of the lithium-ion secondary battery.

[0030] The inverter 242 that drives the motor 246 is supplied with power of high voltage Vh from the fuel cell stack 12 via a boost converter 240. The inverter 242 that drives the motor 246 is also supplied with power of high voltage Vh from a power source 244 via a high voltage relay 245. That is, the motor 246 is supplied with power from the fuel cell stack 12 and / or the power source 244. The inverter 242 converts the supplied high DC voltage Vh into a three-phase AC current to drive the motor 246.

[0031] The power supply 244 is charged by the energy generated by the fuel cell stack 12 when a high DC voltage Vh obtained by boosting the generation voltage Vfc of the fuel cell stack 12 by the boost converter 240 is applied to the power supply 244. When the fuel cell vehicle 11 is decelerating and the motor 246 is in regeneration mode, the three-phase AC current generated by the motor 246 as a generator is converted by the inverter 242 into high DC voltage Vh power and charges the power supply 244 via the high voltage relay 245.

[0032] The control device 26 and various sensors as low-voltage loads, as well as an air conditioner, an electric power steering device, and lighting devices (not shown), are supplied with DC low-voltage Vl from a power source 248. The power source 248 is charged with power obtained by stepping down the high voltage Vh of the power source 244 to the low voltage Vl by a step-down converter 247.

[0033] The air compressor 112 is supplied with three-phase AC power obtained by converting a high voltage Vh from a power source 244 into three-phase AC power by an inverter 252 via a high-voltage relay 245. Any two phases of the three-phase AC power, in this case a U-phase AC current Iu and a V-phase AC current Iv, are detected by current sensors 253 and 254, respectively.

[0034] The control device 26 may be configured by an ECU (Electronic Control Unit). The control device 26 includes a calculation unit 136 and a storage unit 138. The calculation unit 136 is, for example, a processor such as a CPU (Central Processing Unit) or a GPU (Graphics Processing Unit). That is, the calculation unit 136 may be configured by a processing circuit. The calculation unit 136 controls each device by executing computer-executable instructions (programs) stored in the storage unit 138. At least a part of the calculation unit 136 may be realized by an integrated circuit such as an ASIC (Application Specific Integrated Circuit) or an FPGA (Field-Programmable Gate Array). At least a part of the calculation unit 136 may be realized by an electronic circuit including discrete devices.

[0035] The calculation unit 136 includes an acquisition unit 140, a control unit 142, a timer unit 144, and a determination unit 146. The acquisition unit 140 acquires information from electronic components other than the control device 26 (sensors, ECUs, etc.).

[0036] The sensors include the cell voltage sensor 25, hydrogen concentration sensor 111, temperature sensor 130, current sensors 253, 254, pressure sensor 268, and impact sensor 280 attached to the body of the fuel cell vehicle 11, as well as a voltage sensor that detects the generated voltage Vfc, a current sensor that detects the generated current Ifc, a voltage sensor that detects the high voltage Vh, and a voltage sensor that detects the low voltage Vl, all of which are not shown.

[0037] The control unit 142 executes computer-executable commands (programs) based on various signals acquired from the sensors via the acquisition unit 140, and controls the operations of the injector 94, the air compressor 112, the pump 126, the motor 246, the boost converter 240, the inverters 242, 252, the high-voltage relay 245, the step-down converter 247, the valves, etc. The timing unit 144 measures the execution time, etc., using a timer (not shown). The determination unit 146 determines whether or not a surge fault has occurred in the air compressor 112 .

[0038] The storage unit 138 is configured with a volatile memory (not shown) and a non-volatile memory (not shown) which are computer-readable storage media. The volatile memory is, for example, a random access memory (RAM). The non-volatile memory is, for example, a read only memory (ROM) or a flash memory. Data and the like are recorded, for example, in the volatile memory. Programs, tables, maps, and the like are recorded, for example, in the non-volatile memory. At least a part of the storage unit 138 may be provided in the above-mentioned processor, integrated circuit, and the like. A surge determination map 148 is recorded in the storage unit 138.

[0039] Fig. 3 is an explanatory diagram of a surge determination map 148 of the air compressor 112. Fig. 3 shows a graph with the rotation speed Rc (of the rotor shaft 274) of the air compressor 112 on the horizontal axis and the pressure Pc on the vertical axis. The area to the right of a surge determination threshold line 149 shown by a solid line is determined to be a non-surge area, indicating that the air compressor 112 is not in a surge fault state. On the other hand, the area to the left of the threshold line 149 is determined to be a surge area because the pressure Pc is abnormally high relative to the rotation speed Rc, indicating that the air compressor 112 is in a surge fault state.

[0040] The rotation speed Rc of the air compressor 112 can be calculated by the control unit 142 when the control device 26 acquires, via the acquisition unit 140, changes in the U-phase AC current Iu and the V-phase AC current Iv detected by the current sensors 253, 254. Based on a torque command value of the motor 246, the control device 26 performs feedback control by vector control of the three-phase AC current supplied from the inverter 242 to the motor 246 and the three-phase AC currents Iu, Iv, and Iw supplied from the inverter 252 to the air compressor 112.

[0041] [Fluid flow in fuel cell system 10] (1) Fluid flow in the anode system 16 The injector 94 injects the fuel gas supplied from the tank 14 downstream of the fuel gas supply path 84 under pulse width modulation (PWM) control by the control device 26. The fuel gas injected from the injector 94 is supplied to the fuel gas supply port 22a of the fuel cell stack 12 via the fuel gas supply path 84. The fuel gas that has not reacted inside the fuel cell stack 12 is discharged as fuel off-gas from the fuel gas discharge port 22b of the fuel cell stack 12. The fuel off-gas contains hydrogen that has not reacted with oxygen, nitrogen in the oxidant gas that has permeated the MEA 36, and moisture produced by the reaction of oxygen and hydrogen.

[0042] The fuel off-gas is supplied to a gas-liquid separator 98 via a fuel gas discharge passage 86. The gas-liquid separator 98 separates the fuel off-gas into a gas component (fuel off-gas) and a liquid component (water). The fuel off-gas discharged from the gas-liquid separator 98 is supplied to an ejector 96 via a circulation passage 88. In the ejector 96, the fuel off-gas sucked from the gas-liquid separator 98 and the fuel gas injected from the injector 94 join together.

[0043] (2) Fluid flow in the cathode system 18 The air compressor 112 heats and compresses the oxidant gas (air) sucked in from outside the fuel cell vehicle 11, and discharges it downstream of the oxidant gas supply channel 106. The oxidant gas discharged from the air compressor 112 is supplied to the oxidant gas supply port 22c of the fuel cell stack 12 via the oxidant gas supply channel 106 equipped with a cooler (not shown). The oxidant gas that has not reacted inside the fuel cell stack 12 is discharged as oxidant off-gas from the oxidant gas discharge port 22d of the fuel cell stack 12. The oxidant off-gas contains each component contained in the oxidant gas and moisture produced by the reaction of oxygen and hydrogen.

[0044] The oxidant off-gas is discharged to the outside of the fuel cell vehicle 11 through the oxidant gas discharge path 108. The oxidant off-gas contains moisture. In the humidifier 114, a portion of the moisture contained in the oxidant off-gas is used to humidify the oxidant gas flowing through the humidifier supply path 114A.

[0045] (3) Fluid flow in the cooling system 20 The pump 126 discharges the cooling medium toward the cooling medium supply port 22e of the fuel cell stack 12. The cooling medium discharged from the pump 126 is supplied to the cooling medium supply port 22e of the fuel cell stack 12 via the cooling medium supply path 122. The cooling medium that has circulated inside the fuel cell stack 12 is discharged from the cooling medium discharge port 22f of the fuel cell stack 12. The cooling medium discharged from the cooling medium discharge port 22f is supplied to the radiator 128 via the cooling medium discharge path 124. The cooling medium that has dissipated heat in the radiator 128 is sucked into the pump 126.

[0046] [Operation explanation using flow chart] The above is a basic configuration of the fuel cell system 10. Next, an explanation will be given of the operation during an emergency shutdown when the fuel cell system 10 (fuel cell stack 12) needs to be shut down during power generation by the fuel cell system 10 (fuel cell stack 12).

[0047] Here, the detection control operation of the surge fault state of the air compressor 112 by the control section 142 of the control device 26 when the fuel cell system 10 is stopped in an emergency will be described with reference to the flow chart of FIG.

[0048] In step S1, the control unit 142 determines whether or not an emergency shutdown of the fuel cell system 10 is necessary based on the abnormality detection result determined by the determination unit 146 during the power generation operation of the fuel cell stack 12. In this case, the determination unit 146 determines whether or not an emergency shutdown is necessary based on whether or not an abnormality signal (warning signal) is detected via the acquisition unit 140. The abnormal signal here is one of the following three signals:

[0049] First, the impact sensor 280 outputs an abnormality signal (impact detection signal) when it detects an impact equal to or greater than a threshold value due to a collision of the fuel cell vehicle 11, etc. This abnormality signal is passed through the acquisition unit 140 and judged by the judgment unit 146. The impact sensor 280 may be an acceleration sensor. The impact sensor 280 may use an output signal of an airbag system (not shown).

[0050] Secondly, when a voltage drop below the threshold value of the cell voltage Vcell is detected via the cell voltage sensor 25 and the acquisition unit 140, the determination unit 146 detects this as an abnormality signal via the acquisition unit 140. In other words, the cell voltage sensor 25 essentially outputs an abnormality signal.

[0051] Thirdly, the hydrogen concentration sensor 111 detects a hydrogen concentration (fuel gas concentration) Dh equal to or greater than a threshold value. The hydrogen concentration Dh equal to or greater than this threshold value is detected by the determination unit 146 as an abnormality signal via the acquisition unit 140. In effect, the hydrogen concentration sensor 111 outputs an abnormality signal.

[0052] When the determination unit 146 does not detect any abnormal signal (step S1: NO), the control unit 142 repeats the abnormality detection process of step S1. On the other hand, when the determination unit 146 detects an abnormal signal (step S1: YES), the process by the control unit 142 proceeds to step S2.

[0053] In step S2, the control unit 142 sends an instruction {an instruction to decelerate the rotation speed Rc at the (fastest) deceleration characteristic} to the inverter 252 so that the rotation speed Rc of the rotor shaft 274 of the air compressor 112 becomes 0, which is the fastest or the lowest rotation speed within a predetermined time. Note that the instruction to make the rotation speed Rc the fastest or the lowest rotation speed within a predetermined time may be set to 0, which is the fastest and lowest rotation speed within a range in which the air compressor 112 does not break down. Note that the predetermined time may be set from the time it takes for the rotation speed Rc to actually become 0 when the rotation speed instruction to the rotating air compressor 112 becomes 0. Also, at the same time in step S2, the control unit 142 drives the bypass valve 120 to a fully open state. Further, at the same time in step S2, the control unit 142 throttles the inlet seal valve 116 and the outlet seal valve 118 to suppress the inflow of the oxidant gas into the fuel cell stack 12. Further, at the same time in step S2, the control unit 142 immediately stops the drive of the injector 94 to prohibit the discharge of fuel gas from the tank 14.

[0054] In step S3, the control unit 142 performs feedback control of the inverter 252 so that the rotation speed Rc of the rotor shaft 274 decreases in accordance with a deceleration command for the rotation speed Rc while monitoring the rotation speed Rc of the rotor shaft 274 based on the U-phase AC current Iu and the V-phase AC current Iv detected by the current sensors 253 and 254. In addition, in step S3, the control unit 142 maintains the ON state of the high-voltage relay 245, and maintains a state in which power from the power source 244 can be supplied to the inverter 252. In this state, the process by the control unit 142 proceeds to step S4.

[0055] In step S4, the control unit 142 detects whether or not the air compressor 112 is in a surge fault state through the determination unit 146. The surge fault detection process in step S4 is continuously executed under the rotation speed monitoring in which the control unit 142 performs the feedback control in step S3. In step S4, the determination unit 146 detects the pressure Pc of the discharge port 302 of the air compressor 112 from the pressure sensor 268 through the acquisition unit 140. In step S4, the determination unit 146 uses the rotation speed Rc of the rotor shaft 274 based on the U-phase AC current Iu and the V-phase AC current Iv and the pressure Pc of the air compressor 112 as arguments, and refers to the surge determination map 148 (FIG. 3) to determine whether or not the air compressor 112 is in a surge region. If the air compressor 112 is in the surge region, the determination unit 146 determines that the air compressor 112 is in a surge fault state and drives the bypass valve 120 in the fully open direction. If it is in the non-surge region, the determination unit 146 determines that the air compressor 112 is not in a surge fault state. The process by the control unit 142 proceeds to step S5.

[0056] In step S5, the determination unit 146 determines whether the bypass valve 120 is fully open or not based on the opening degree signal of the bypass valve 120 acquired through the acquisition unit 140. If the bypass valve 120 is not fully open (step S5: NO), the control device 26 repeats the processes of steps S2 to S5. If the bypass valve 120 is fully open (step S5: YES), the process by the control unit 142 proceeds to step S6.

[0057] In step S6, the timer 144 starts counting the predetermined time Tth using a timer, and the determination unit 146 determines through the timer 144 whether the predetermined time Tth has elapsed since the bypass valve 120 was fully opened. The predetermined time Tth is a time for confirming that the bypass valve 120 is reliably maintaining the fully open state. If the predetermined time Tth has not elapsed (step S6: NO), the control unit 142 repeats the processes from step S2 to step S6: NO without resetting the timer in step S6. If the timer 144 has counted the predetermined time Tth in step S6 (step S6: YES), the process by the control unit 142 proceeds to step S7.

[0058] In step S7, the control unit 142 transitions the high voltage relay 245 from an on state to an off state. As a result, the high voltage Vh is no longer applied to the inverter 242 and the inverter 252. In this way, the control unit 142 stops driving and controlling the air compressor 112 through the inverter 252. At the same time, the control unit 142 stops driving and controlling the motor 246 through the inverter 242. At the same time, in step S7, the control unit 142 closes the inlet seal valve 116 and the outlet seal valve 118. At the same time, in step S7, the control unit 142 transitions the protection completion flag in the memory unit 138 from an incomplete state to a completed state. The protection completion flag is sent to related devices inside and outside the fuel cell vehicle 11.

[0059] [Operation explanation using time chart] An example of the operation described with reference to the flowchart in FIG. 4 will be described with reference to the time chart in FIG. 5, while omitting repetition of the operation description.

[0060] 5, during power generation by the fuel cell system 10 (fuel cell stack 12), the control unit 142 detects an abnormality signal through the determination unit 146 (corresponding to YES in step S1). Upon detection, the control unit 142 immediately sends an instruction (an instruction to decelerate the rotation speed Rc for the fastest deceleration characteristics) indicated by the dashed line to the inverter 252 so that the rotation speed Rc of the rotor shaft 274 of the air compressor 112 becomes 0, which is the fastest and lowest rotation speed, while keeping the high voltage relay 245 on (corresponding to step S2). At time t0, the control unit 142 drives the bypass valve 120 in the fully open direction.

[0061] The control unit 142 feedback controls the rotation speed Rc of the rotor shaft 274 of the air compressor 112 from time t0 to time t1 as indicated by the solid line (corresponding to step S3).

[0062] From time t0 to time t2, the control unit 142 detects whether the air compressor 112 is in a surge fault state by referring to the surge determination map 148 based on the rotation speed Rc and the pressure Pc (corresponding to step S4). When the bypass valve 120 is fully opened at time t1, the control unit 142 starts timing the predetermined time Tth with the timer unit 144 (corresponding to step S5: YES). At time t2 when the predetermined time Tth has elapsed (corresponding to step S6: YES), the control unit 142 transitions the high voltage relay 245 from the ON state to the OFF state. This stops the control unit 142 from driving and controlling the air compressor 112 through the inverter 252. At the same time, the control unit 142 transitions the protection completion flag from the incomplete state to the completed state.

[0063] [Explanation of the Effects of the Embodiments] When the control device 26 acquires an abnormality signal from the fuel cell system 10 (when the need for an emergency shutdown of the fuel cell stack 12 arises), it opens the bypass valve 120 while continuing the supply of power from the power source 244 to the inverter 252 that drives the air compressor 112. When a predetermined time Tth has elapsed since the bypass valve 120 that allows the oxidant gas to flow into the bypass flow path 110 was opened, the supply of power from the power source 244 to the air compressor 112 is stopped.

[0064] In this case, for example, as shown in FIG. 5, the supply of power from the power source 244 to the inverter 252 continues for a duration Tw (see FIG. 5) even after the control unit 142 detects an abnormality signal at time t0.

[0065] Therefore, when the need arises for an emergency shutdown of the fuel cell stack 12, the control unit 142 can detect whether or not a surge fault has occurred in the air compressor 112 based on the U-phase AC current Iu and the V-phase AC current Iv (rotation speed Rc) and the pressure Pc before stopping the supply of power to the air compressor 112.

[0066] [Comparative Example] 6 shows a time chart of a comparative example. In the comparative example, when an abnormal signal is detected at time t0, the high voltage relay 245 is switched from the ON state to the OFF state. Therefore, the rotation speed Rc of the rotor shaft 274 of the air compressor 112 cannot be grasped. The rotation speed Rc naturally approaches 0.

[0067] [Variations] FIG. 7 shows a flowchart of the modified example. In the processing of the flowchart in FIG. 7, the processing of steps S1 to S4 and step S7 are the same as the processing of the flowchart in FIG. In this modification, when the control unit 142 detects a surge failure in step S4, the control unit 142 drives the bypass valve 120 in the fully open direction in step S5a, and then transitions to the process in step S6a. In step S6a, the control unit 142 determines whether a predetermined time, here a duration Tw (see FIG. 5), has elapsed since the detection of the surge fault (time t0 in FIG. 5) based on the time measured by the timer unit 144 (timer measurement). Note that the duration Tw is the duration of power supply from the power source 244 to the inverter 252 after the abnormal signal is detected. If the duration Tw has not elapsed (step S6a: NO), the control unit 142 repeats the processes from step S2 to step S6a without resetting the timer in step S6a. If the timing unit 144 has timed the duration Tw in step S6a (step S6a: YES), the process by the control unit 142 proceeds to step S7. In step S7, the control unit 142 transitions the high voltage relay 245 from an on state to an off state. As a result, the high voltage Vh is no longer applied to the inverter 242 and the inverter 252. In this way, the control unit 142 stops driving and controlling the air compressor 112 through the inverter 252. At the same time, the control unit 142 stops driving and controlling the motor 246 through the inverter 242. At the same time, in step S7, the control unit 142 closes the inlet seal valve 116 and the outlet seal valve 118. At the same time, in step S7, the control unit 142 transitions the protection completion flag from an incomplete state to a completed state. The protection completion flag is sent to related devices inside and outside the fuel cell vehicle 11.

[0068] [Note] In addition to the above disclosure, the following notes are also disclosed. (Appendix 1) The first disclosure relates to a fuel cell stack (12) including a plurality of power generation cells (24) that generate power from an oxidant gas and a fuel gas, an air compressor (112) that supplies the oxidant gas to the fuel cell stack via an oxidant gas supply passage (106), a power source (244) that can supply power to the air compressor, a bypass valve (120) provided in a bypass flow passage (110) that connects the oxidant gas supply passage and an oxidant gas discharge passage (108) of the fuel cell stack, and a control device that controls the fuel cell stack, the air compressor, the power source, and the bypass valve. and a control device (26) for controlling the fuel cell system (10) including: an acquisition unit (140) that acquires an abnormality signal that requires an emergency shutdown of the fuel cell system; a control unit (142) that, when the acquisition unit acquires the abnormality signal, opens the bypass valve while continuing the supply of power to the air compressor, and stops the supply of power to the air compressor after the bypass valve has been opened; and a determination unit (146) that, when the abnormality signal is acquired, determines whether or not a surge fault has occurred in the air compressor while continuing the supply of power.

[0069] According to the above configuration, when the control device acquires an abnormality signal of the fuel cell system (when the need for an emergency shutdown of the fuel cell stack arises), the control device opens the bypass valve while continuing to supply power from the power source to the air compressor, and while continuing to supply the power, determines whether or not a surge fault has occurred in the air compressor.

[0070] Therefore, when an emergency shutdown of the fuel cell stack becomes necessary, the control device can detect whether or not the air compressor is in a surge fault state before stopping the supply of power to the air compressor.

[0071] (Appendix 2) In the fuel cell system described in Supplementary Note 1, when the control unit acquires the abnormality signal through the acquisition unit, the control unit reduces the rotation speed of the air compressor with deceleration characteristics such that the rotation speed (Rc) becomes 0 within a predetermined time, thereby making it possible to protect the air compressor in a short time. (Appendix 3) In the fuel cell system described in appendix 1, the control unit determines whether the opening of the bypass valve has been completed based on the amount of opening of the bypass valve, or after a predetermined time has elapsed since the abnormality signal was detected. Based on the completion determination, the air compressor can be reliably protected. (Appendix 4) In the fuel cell system described in Supplementary Note 1, the presence or absence of the surge failure is determined based on at least the rotation speed of the air compressor or a physical quantity based on the rotation speed. The physical quantity can be the flow rate of the air compressor detected (measured) by a flow sensor or the outlet pressure of the air compressor detected (measured) by a pressure sensor. (Appendix 5) The fuel cell system described in Supplementary Note 1 may further include a cell voltage sensor (25) that detects the voltage of the power generation cell, and the acquisition unit may acquire the abnormality signal from the cell voltage sensor. In this case, the control device can detect the presence or absence of a surge fault in the air compressor when an emergency shutdown of the fuel cell stack is required based on the voltage signal output from the cell voltage sensor.

[0072] (Appendix 6) The fuel cell system described in Supplementary Note 1 may further include an impact sensor (280) that detects an impact applied to the fuel cell stack and outputs an impact detection signal, and the acquisition unit may acquire the impact detection signal from the impact sensor as the abnormality signal. In this case, the control device can detect the presence or absence of a surge fault state in the air compressor when an emergency stop of the fuel cell stack is required based on the abnormality signal output from the impact sensor.

[0073] (Appendix 7) The fuel cell system described in Supplementary Note 1 may further include a fuel gas concentration sensor (111) for monitoring a fuel gas concentration in a cathode flow path (50) of the fuel cell stack, and the acquisition unit may acquire a fuel gas concentration equal to or greater than a threshold value detected by the fuel gas concentration sensor as the abnormality signal. In this case, the control device can detect the presence or absence of a surge fault in the air compressor when an emergency shutdown of the fuel cell stack is required based on the abnormality signal output from the fuel gas concentration sensor.

[0074] (Appendix 8) The fuel cell system described in Supplementary Note 1 further includes an inverter (252) that converts the power having a DC voltage supplied from the power source via a relay (245) into a three-phase AC current and supplies the three-phase AC current to a stator coil (272) that rotates a rotor shaft (274) of the air compressor, and when the control unit acquires the abnormality signal through the acquisition unit, the control unit maintains the on state of the relay, reduces the rotation speed of the rotor shaft of the air compressor with the fastest deceleration characteristic, opens the bypass valve, and transitions the relay from the on state to the off state after the bypass valve has been opened. With the above configuration, the rotation speed of the air compressor can be determined from the three-phase AC current even after the abnormality signal is acquired.

[0075] (Appendix 9) The fuel cell system described in appendix 1 may further include a pressure sensor (268) that detects a pressure (Pc) in the oxidant gas supply path, and the determination unit may determine whether or not a surge fault has occurred in the air compressor based on the rotation speed of the air compressor (rotor shaft) and the pressure detected by the pressure sensor. With the above configuration, a surge fault in the air compressor can be immediately determined.

[0076] (Appendix 10) In the fuel cell system described in Supplementary Note 1, the air compressor includes a rotor shaft having an impeller (276) and supported by an air bearing (292), and a stator coil for rotating the rotor shaft. According to the above configuration, the rotation speed of the rotor shaft of a so-called turbo air compressor that does not have a rotation speed sensor can be detected by a three-phase AC current flowing through the stator coil.

[0077] (Appendix 11) The second disclosure is a control method for a fuel cell system including a fuel cell stack having a plurality of power generating cells that generate power using an oxidant gas and a fuel gas, an air compressor that supplies the oxidant gas to the fuel cell stack via an oxidant gas supply path, a power source that supplies power to the air compressor, a bypass valve provided in a bypass flow path that connects the oxidant gas supply path and an oxidant gas exhaust path of the fuel cell stack, and a control device that controls the fuel cell stack, the air compressor, the power source, and the bypass valve, wherein the control device acquires an abnormality signal that requires an emergency shutdown of the fuel cell system, and when the control device acquires the abnormality signal, opens the bypass valve while continuing to supply the power from the power source to the air compressor, and stops the supply of power to the air compressor after the bypass valve has been opened, and when the control device acquires the abnormality signal, determines whether or not there is a surge failure in the air compressor while continuing to supply power.

[0078] According to the above configuration, when the control device acquires an abnormality signal of the fuel cell system (when the need for an emergency shutdown of the fuel cell stack arises), the control device opens the bypass valve while continuing to supply power from the power source to the air compressor, and while continuing to supply the power, determines whether or not a surge fault has occurred in the air compressor.

[0079] Therefore, when an emergency shutdown of the fuel cell stack becomes necessary, the control device can detect whether or not the air compressor is in a surge fault state before stopping the supply of power to the air compressor.

[0080] The present invention is not limited to the above disclosure, and various configurations can be adopted without departing from the gist of the present invention. [Explanation of symbols]

[0081] 10...Fuel cell system 11...Fuel cell vehicle 12... fuel cell stack 16... anode system 18...Cathode system 21...Load 24...power generation cell 26...control device 27...Power supply system 28, 30...Separator 32...Electrolyte membrane / electrode structure 36...MEA 38...anode electrode 40...cathode electrode 50: cathode flow passage; 66: anode flow passage 106 (106A)…Oxidant gas supply path 108(108A)…Oxidant gas exhaust passage 109... discharge passage 110... bypass passage 112...Air compressor 116...Inlet sealing valve 118: Outlet sealing valve 120: Bypass valve 136...Calculation section 138...Storage section 140: Acquisition unit 142: Control unit 144...Time measurement section 146...Judgment section 148...Surge judgment map 240...Boost converter 242, 252...Inverter 244...Power supply 245…High voltage relay 246…Motor

Claims

1. a fuel cell stack including a plurality of power generation cells that generate power using an oxidant gas and a fuel gas; an air compressor for supplying the oxidant gas to the fuel cell stack through an oxidant gas supply passage; A power source capable of supplying power to the air compressor; a bypass valve provided in a bypass flow path connecting the oxidant gas supply path and an oxidant gas discharge path of the fuel cell stack; a control device that controls the fuel cell stack, the air compressor, the power source, and the bypass valve; A fuel cell system comprising: The control device includes: an acquisition unit that acquires an abnormality signal that requires an emergency shutdown of the fuel cell system; a control unit that, when the acquisition unit acquires the abnormality signal, opens the bypass valve while continuing the supply of power to the air compressor, and stops the supply of power to the air compressor after the bypass valve has been opened; a determination unit that, when the abnormality signal is acquired, determines whether or not a surge fault has occurred in the air compressor while continuing to supply the power; A fuel cell system comprising:

2. 2. The fuel cell system according to claim 1, The control unit is When the abnormality signal is acquired through the acquisition unit, the rotation speed of the air compressor is reduced with a deceleration characteristic such that the rotation speed becomes 0 within a predetermined time. Fuel cell system.

3. 2. The fuel cell system according to claim 1, The control unit determines whether or not the bypass valve has been opened based on an opening amount of the bypass valve, or whether or not the bypass valve has been opened after a predetermined time has elapsed since the abnormality signal was detected. Fuel cell system.

4. 2. The fuel cell system according to claim 1, The determination of the presence or absence of a surge fault is made based on at least the rotation speed of the air compressor or a physical quantity based on the rotation speed. Fuel cell system.

5. 2. The fuel cell system according to claim 1, a cell voltage sensor that detects a voltage of the power generation cell; the acquisition unit acquires the abnormality signal from the cell voltage sensor; Fuel cell system.

6. 2. The fuel cell system according to claim 1, a shock sensor that detects a shock applied to the fuel cell stack and outputs a shock detection signal; the acquiring unit acquiring the shock detection signal from the shock sensor as the abnormality signal; Fuel cell system.

7. 2. The fuel cell system according to claim 1, a fuel gas concentration sensor for monitoring a fuel gas concentration in a cathode flow path of the fuel cell stack; the acquiring unit acquires, as the abnormality signal, a fuel gas concentration equal to or higher than a threshold value detected by the fuel gas concentration sensor; Fuel cell system.

8. 2. The fuel cell system according to claim 1, an inverter that converts the power having a DC voltage supplied from the power source via a relay into a three-phase AC current and supplies the AC current to a stator coil that rotates a rotor shaft of the air compressor; The control unit is When the abnormality signal is acquired through the acquisition unit, the relay is maintained in an on state, the rotation speed of the rotor shaft of the air compressor is reduced with a maximum deceleration characteristic, and the bypass valve is opened, and after the bypass valve has been completely opened, the relay is transitioned from the on state to an off state. Fuel cell system.

9. 2. The fuel cell system according to claim 1, a pressure sensor that detects the pressure of the oxidant gas supply path; The determination unit determines whether or not a surge fault occurs in the air compressor based on a rotation speed of the air compressor and a pressure detected by the pressure sensor. Fuel cell system.

10. 2. The fuel cell system according to claim 1, The air compressor is a rotor shaft having an impeller and supported by an air bearing; A stator coil for rotating the rotor shaft; A fuel cell system comprising:

11. a fuel cell stack including a plurality of power generation cells that generate power using an oxidant gas and a fuel gas; an air compressor for supplying the oxidant gas to the fuel cell stack through an oxidant gas supply passage; a power source for powering the air compressor; a bypass valve provided in a bypass flow path connecting the oxidant gas supply path and an oxidant gas discharge path of the fuel cell stack; a control device that controls the fuel cell stack, the air compressor, the power source, and the bypass valve; A control method for a fuel cell system comprising: The control device includes: obtaining an abnormality signal indicating that an emergency shutdown of the fuel cell system is required, and when the abnormality signal is obtained, opening the bypass valve while continuing the supply of power from the power source to the air compressor, and stopping the supply of power to the air compressor after the bypass valve has been opened, and when the abnormality signal is obtained, determining whether or not a surge fault has occurred in the air compressor while continuing the supply of power. A method for controlling a fuel cell system.

Images