Fuel cell drive device and method for sensing abnormal operation of fuel cell

Abstract

A fuel cell drive device is provided. The fuel cell drive device includes a fuel cell ECU that controls operation of a fuel cell, and a step-down converter that converts a voltage of a high-voltage battery to a low voltage that is an operating voltage of the fuel cell ECU and the like. The fuel cell ECU turns on a start signal to the step-down converter when an instruction to start operation is received, and receives supply of the low voltage from the step-down converter, and determines whether or not the operation of the step-down converter is good according to a first state that is a state of the supply of the low voltage. Further, in a case where it is determined that the operation of the step-down converter is normal, a hold circuit that maintains the operation of the step-down converter even when the start signal is disabled is operated, and an output of the start signal is set to off in this state, and a state of the supply of the low voltage from the step-down converter at this time is recorded as a second state when the operation of the fuel cell is stopped.

Description

Technical Field

[0001] This invention relates to a technology for driving fuel cells. Background Technology

[0002] In the early stages of fuel cell development, fuel cells that used hydrogen or methanol reformate as fuel to generate electricity and the systems that controlled these fuel cells were developed and used as a single unit. However, with the increasing versatility of fuel cells, fuel cells or the control devices that control them have become separate products. These control devices include, in addition to the electronic control unit (ECU) that controls the operation of the fuel cell, DC / DC converters that convert the voltage of the high-voltage power system used for driving the fuel cell to the constant-voltage power system used for driving the ECU or auxiliary equipment.

[0003] In such control devices, an anomaly detection mechanism is assembled to deal with the occurrence of malfunctions, etc. Patent Document 1 disclosed a structure that is equipped with various sensors to measure the voltage or current of a battery, detects battery anomalies, and determines the nature of the anomalies.

[0004] Patent Document 1: Japanese Patent Application Publication No. 2007-225562 Summary of the Invention

[0005] However, it is difficult to integrate the diagnostic functions traditionally found in fuel cell systems into the individual control unit. Furthermore, assembling new sensors solely for detecting anomalies would increase the cost of the individual control unit. Moreover, if it is impossible to pinpoint which part experienced the anomaly, the overall reliability of the assembled fuel cell system cannot be guaranteed.

[0006] The present invention can be implemented in the following manner or in the following application examples.

[0007] (1) The fuel cell drive device of the present invention can be implemented in the following manner. The fuel cell drive device includes: a fuel cell ECU (FCECU) that receives a power supply and controls the operation of a fuel cell including a fuel cell main body and an auxiliary unit; and a buck converter that converts the voltage of a high-voltage battery corresponding to the generation voltage of the fuel cell into a low voltage that serves as the operating voltage of the fuel cell ECU and the auxiliary unit. The fuel cell ECU performs the following control: when receiving an instruction to start operation from the outside, it sets the output of a start signal that causes the buck converter to start outputting the low voltage to be turned on, and receives the low voltage supply from the buck converter; it determines whether the operation of the buck converter is good based on a first state that is the received low voltage supply state, and when it is determined that the operation of the buck converter is normal, it uses the low voltage output to activate a holding circuit that outputs a holding signal that maintains the operation of the buck converter even if the start signal fails; and when the holding circuit is activated, it sets the output of the start signal to be turned off, and records the low voltage supply state from the buck converter at this time as a second state when the operation of the fuel cell is stopped. Thus, the first state can be used to identify and determine the malfunction of the buck converter, and the second state can be used to identify and determine the malfunction of the holding circuit driven by the holding signal. Here, the malfunction of the buck converter or the holding circuit includes not only circuit faults themselves, but also malfunctions such as broken signal lines that cause each circuit to operate.

[0008] (2) The present invention can also be implemented as an anomaly sensing method for fuel cell drive devices. This anomaly detection method is based on a structure that converts the voltage of a high-voltage battery corresponding to the power generation voltage of the fuel cell into a low-voltage buck converter, which serves as the operating voltage for the fuel cell ECU and auxiliary equipment controlling the operation of the fuel cell. The method performs the following steps: Upon receiving an external indication to start operation, the fuel cell ECU sets the output of a start signal that causes the buck converter to output the low voltage to be turned on, and receives the low voltage supply from the buck converter; Based on a first state, which is the received low voltage supply state, it is determined whether the buck converter is operating properly; and if the buck converter is determined to be operating properly, a holding circuit that outputs a holding signal to maintain the operation of the buck converter even if the start signal fails is activated using the low voltage output; while the holding circuit is activated, the output of the start signal is turned off; when the fuel cell operation is stopped, the low voltage supply state from the buck converter, i.e., a second state, is recorded; and when the fuel cell operation starts again, it is determined, based on the recorded second state, that the holding of the buck converter's operation based on the holding circuit has not functioned properly. In this way, without the need for special diagnostic computers, it is easy to detect abnormalities in the structure driving the fuel cell. Attached Figure Description

[0009] Figure 1 This is a schematic structural diagram of a fuel cell system including the fuel cell drive device of the embodiment.

[0010] Figure 2 This is a structural diagram of a fuel cell drive unit.

[0011] Figure 3 This is a process flow diagram representing part of the start-up sequence of a fuel cell.

[0012] Figure 4 It is a sequence diagram that represents the action state of each part.

[0013] Figure 5 This is a flowchart representing the FC startup sequence based on the fuel cell ECU (FCECU).

[0014] Figure 6 This is a flowchart indicating the process of stopping the fuel cell. Detailed Implementation

[0015] A. Implementation Method 1:

[0016] (A1) Overall structure of the fuel cell system:

[0017] A schematic structure of the fuel cell system 200, including the fuel cell drive device 100 of the first embodiment, is shown below. Figure 1 As shown in the figure, the fuel cell system 200 includes: a fuel cell 10; a fuel cell drive unit 100 that drives the fuel cell 10; a host electronic control unit (hereinafter referred to as the host ECU) 190 that instructs the start / stop of the fuel cell drive unit 100; a load, i.e., a motor 70; and an inverter 61 that drives the motor 70, etc. The motor 70 can be, for example, a drive motor for driving a vehicle, in which case the fuel cell system 200 is mounted on a fuel cell vehicle. Of course, the load is not limited to the motor 70, and can also be electronic components such as a heater or a computer.

[0018] The fuel cell system 200 of this embodiment is configured as a system, but the fuel cell 10 and the fuel cell drive unit 100 are not specifically developed for the system; from a system perspective, they are assembled as general-purpose components for external sale. Therefore, the motor 70, which serves as a load, or the inverter 61 that drives the motor 70, receives the drive voltage supply via the fuel cell drive unit 100, but the operation control of the motor 70 via the inverter 61 is performed by the upper-level ECU 190. Alternatively, the power supply to the inverter 61 can be performed directly without going through the fuel cell drive unit 100.

[0019] The fuel cell 10 includes a fuel cell stack 20 formed by stacking multiple fuel cell units 25, an oxygen supply system 30 for supplying oxygen-containing gas (air) to the fuel cell stack 20, and a fuel gas supply system 40 for supplying fuel gas (hydrogen) to the fuel cell stack 20. In the fuel cell stack 20, multiple fuel cell units 25 are stacked in the Y direction shown in the figure, and end plates 21 and 22 are provided at both ends. The end plates 21 and 22 have current collectors on their inner sides, but these are not shown individually and are shown as a single unit. Two hydrogen through holes (not shown), two air through holes, and two cooling water through holes are provided within the surface of each fuel cell unit 25. The hydrogen through holes, formed by stacking the fuel cell units 25, constitute a hydrogen supply manifold 23 and a hydrogen exhaust manifold 24. Air supply and exhaust manifolds or cooling water supply and exhaust manifolds are also formed by stacking the fuel cell units 25, but these are not shown in the figure.

[0020] An oxygen supply system 30, which supplies oxygen-containing gas (air) to the fuel cell stack 20, includes a pump 31 that supplies air drawn in through an air filter (not shown) to the air supply manifold of the fuel cell stack 20. A fuel gas supply system 40, which supplies hydrogen as fuel gas to the fuel cell stack 20, includes: a gas tank 41 storing high-pressure hydrogen; a main shut-off valve 43 installed at the threaded port of the gas tank 41; a pressure regulating valve 44 reducing and adjusting the pressure of the hydrogen supplied from the gas tank 41 through the main shut-off valve 43; an injector 45 for blowing depressurized hydrogen into the fuel cell stack 20; a fuel gas circulation system 50 that circulates used fuel gas discharged from the fuel cell stack 20 on the supply side; a hydrogen pump 52 installed in the fuel gas circulation system 50; a gas-liquid separator 46 installed in the fuel gas circulation system 50; and a drain / vent valve 47 for discharging the separated water and exhaust gas to the outside.

[0021] If the main shut-off valve 43 of the high-pressure hydrogen stored in the gas tank 41 is opened, hydrogen is supplied from the injector 45 to the hydrogen supply manifold 23 of the fuel cell stack 20 via the pressure regulating valve 44. The hydrogen supplied to the hydrogen supply manifold 23 is supplied to each of the stacked fuel cell units 25. The supplied hydrogen is used to generate electricity in the fuel cell unit 25, but the remaining hydrogen is sent to the fuel gas circulation system 50 via the hydrogen exhaust manifold 24 and returned to the hydrogen supply pipe 48 by the hydrogen pump 52. In addition, water and exhaust gas separated from the gas-liquid separator 46 provided in the fuel gas circulation system 50 are discharged to the outside. A pressure sensor 71 for measuring the partial pressure PH of the fuel gas is provided in the fuel gas circulation system 50, and a pressure sensor 72 for measuring the supply gas pressure IP is provided in the hydrogen supply pipe 48 between the injector 45 and the inlet of the hydrogen supply manifold 23.

[0022] (A2) Structure of the fuel cell drive unit 100:

[0023] As shown in the figure, the fuel cell drive unit 100 includes: a fuel cell electronic control unit (hereinafter referred to as "FCECU") 110 for controlling the operation of the fuel cell stack 20; a high-voltage battery 120 for storing the generated power of the fuel cell 10; a low-voltage battery 130 for storing 24 volts of power after stepping down the voltage (approximately 800 volts) of the high-voltage battery 120; and direct current converters (DDC) 140 to 142 for voltage conversion. Fuel cell auxiliary equipment (hereinafter referred to as FC auxiliary equipment) 131 to 134 are also shown in the figure, but in reality, these are electrical devices such as pump 31 or hydrogen pump 52 used for the operation of the fuel cell stack 20. Hereinafter, in explaining the operation of the fuel cell drive unit 100, such electrical equipment will be shown as FC auxiliary equipment to include it. Alternatively, the high-voltage battery 120 and the low-voltage battery 130 may not be included in the fuel cell drive unit 100. In this case, the fuel cell drive unit 100 only needs to receive a 24-volt supply from the step-down converter 140 described later.

[0024] The connections and functions of the various parts of the fuel cell drive unit 100 are explained. For example... Figure 2 As shown, approximately 800 volts of DC power from the fuel cell stack 20 is supplied to the high-voltage battery 120 for charging. The power stored in the high-voltage battery 120 is then... Figure 1 The inverter 61 shown is used to drive the motor 70. Since the inverter 61 is controlled by the host ECU 190, therefore... Figure 2 The diagrams illustrating their connections are omitted. The output of the high-voltage battery 120 is input to the buck converter 140. The buck converter 140 converts approximately 800 volts of DC high voltage to a low voltage (approximately 24 volts) DC voltage. In the diagram, the 24-volt DC output of the buck converter 140 is represented by two parallel lines. This 24-volt output is input to the FCECU 110 and is also connected to the power terminals of the first buck converter 141 and the second buck converter 142.

[0025] As shown in the figure, the FCECU110 includes a startup circuit 111, a CPU 112, and a memory 113. A portion of the memory 113 is configured as a non-volatile memory, such as an EEPROM, to store flags F1 to F3, which will be described later. A 24-volt DC voltage from a buck converter 140 is input to the startup circuit 111, but this DC voltage is separate from the overall power supply line of the FCECU110. Power is not supplied to the FCECU110 from the 24-volt DC voltage line connected to the startup circuit 111. The startup circuit 111 is related to the startup of the FCECU110. Until the startup sequence described later is executed through the startup circuit 111, the FCECU110 is kept in a power-off state and does not consume power.

[0026] The FCECU110's start circuit 111 has a simple constant voltage circuit (not shown) that connects to a 24-volt voltage line and internally converts it to 12 volts. The start circuit 111 operates with a small amount of standby power even when the FCECU110 is not in operation. The start circuit 111 is connected to the host ECU190 by receiving a start indication signal Igp from the host ECU190, and is connected to the start terminal wp of the first buck converter 141 via the buck converter start signal line (hereinafter referred to as the start signal line) Sma.

[0027] In the first buck converter 141, in addition to the start terminal wp, an operation holding terminal cp is also provided. The connection and function of the operation holding terminal cp will be explained in detail later. The first buck converter 141 steps down the 24-volt input voltage to 12 volts. The stepped-down 12-volt output is input to the first power supply terminal +B and the voltage detection terminal Vt of the FCECU 110. In the figure, this 12-volt output +B is depicted with a thick line. The 12-volt output +B is connected to one terminal of the normally open contact of the first relay 151, which forms part of the holding circuit; the other terminal of the normally open contact is connected to the FC auxiliary units 133 and 134. That is, if the first relay 151 actuates and the normally open contact is closed, the 12-volt output +B is output to the FC auxiliary units 133 and 134, and these FC auxiliary units begin to operate.

[0028] The 12-volt output +B serves as the power supply for FC auxiliary equipment, and also functions as a continuous holding signal Shd indicating the operation of the first and second buck converters 141 and 142. The second buck converter 142 has essentially the same internal structure / function and connection terminals as the first buck converter 141. In the figure, the signal line transmitting the 12-volt output +B as signal Shd is depicted as a thinner solid line than the 12-volt output +B. This holding signal Shd is connected to the operation holding terminal cp of the first buck converter 141, the start terminal wp of the second buck converter 142, and the operation holding terminal cp. Furthermore, the 12-volt output +BP of the second buck converter 142 is input to the second power input terminal +BP of the FCECU 110 via the normally open contact of the second relay 152, and is directly output to the FC auxiliary equipment 131 and 132.

[0029] The relay drive terminals of the first relay 151 and the second relay 152 are connected to the output port of the FCECU 110. If the relay operation signal Sr from the output port becomes active, the first and second relays 151 and 152 operate, causing their normally open contacts to conduct, i.e., they are in a conducting state. Alternatively, in this embodiment, the two relays 151 and 152 are operated by the same relay operation signal Sr, but they can also be connected to the two output ports of the FCECU 110 respectively, so that they operate at different times, for example, the second relay 152 conducts after the first relay 151 conducts.

[0030] Based on the above structure, refer to Figure 3 The fuel cell start-up sequence 1 is explained when the start signal Igp from the host ECU 190 is input. Figure 3 This is a flowchart illustrating the start-up sequence 1 of the fuel cell 10 based on the fuel cell drive unit 100, performed by the start-up circuit 111. This start-up sequence 1 is not performed by the CPU 112 of the FCECU 110, but by the start-up circuit 111, i.e., a discrete circuit structure. Alternatively, it can be implemented by a low-power microcomputer.

[0031] Figure 3 The process shown repeats step D91 during the standby period of the startup circuit 111. Step D91 is the process of determining whether a start-up signal Igp from the host ECU 190 has not been input. The startup circuit 111 repeats step D91 until a start-up signal Igp is input. If it is determined that a start-up signal Igp has been input from the host ECU 190 (step D91: "Yes"), the startup circuit 111 sets the startup signal line Sma to a high level (step D92). The startup signal line Sma is set to time t0 at the moment the start-up signal Igp is input, and remains at a high level until time t1, then returns to a low level. That is, a single rectangular signal is output to the startup signal line Sma. Then, it waits until time t2 (step D93), sets the moment the start-up signal Igp is input to time t0, and when it becomes a shorter elapsed time than time t1, i.e., time t2 (step D93: "Yes"), the flag F1 is set according to the voltage of the voltage detection terminal Vt (step D94).

[0032] The states of each part from process D91 to process D94 are illustrated in the following example. Figure 4As shown in the figure, the time when the start signal Igp is input from the upper ECU 190 is set as time t0, and the start signal line Sma remains at a high level before time t1. This start signal line Sma is connected to the start terminal wp of the first buck converter 141, and the first buck converter 141 starts operating. As a result, a 12-volt output +B is applied to the first power supply terminal +B of the FCECU 110, and the FCECU 110 is started. At the same time, the start circuit 111 references the voltage of the voltage detection terminal Vt. At time t2, the voltage detection terminal Vt is at a high level, that is, if it is 12 volts, the value 1 is set as flag F1, otherwise the value F1 is set to 0. Flag F1 corresponds to the supply state of the 12-volt output +B from the first buck converter 141, that is, the first state. Regarding the flag in the startup circuit 111, if the startup circuit 111 is a discrete circuit structure, it can be set, for example, by an RS flip-flop. If the startup circuit 111 is composed of a PAL including non-volatile memory, it can be set by logically writing to the non-volatile memory. Of course, if the startup circuit 111 is composed of a low-power microcomputer, it can be set by writing to the non-volatile memory built into the microcomputer.

[0033] exist Figure 3 After the FC boot sequence 1 shown, start Figure 5 The FC startup sequence 2 is shown. This sequence is executed by the CPU 112 of FCECU 110. That is, Figure 5 This is a flowchart illustrating the process executed by CPU 112. This process begins by supplying the 12-volt output +B of the first buck converter 141, which is activated by the start-up circuit 111 setting the start signal line Sma high, to the first power terminal +B of the FCECU 110. After an initialization process (not shown in particular), CPU 112 checks the value of flag F2 in a non-volatile memory stored in a portion of memory 113 (step S101). Regarding flag F2, although it will be described later, if the fuel cell drive unit 100 operates normally and the FCECU 110 completes the process normally, flag F2 is set to the value 1.

[0034] Therefore, it is then determined whether flag F2 is 1 (step S105). If F2 = 1 (step S105: "Yes"), then FCECU110 outputs a relay action signal Sr (step S111). If the relay action signal Sr is output, that is, it is activated, then as follows... Figure 2As shown, both the first relay 151 and the second relay 152 are turned on, i.e., their normally open contacts are closed. As a result, the 12-volt output +B of the first buck converter 141 is output to the FC auxiliary machines 133 and 134, thereby starting these auxiliary machines. Simultaneously, the holding signal Shd, which uses the 12-volt output +B as a signal, also becomes active / high. Consequently, the operation holding terminal cp of the first buck converter 141 and the start terminal wp and operation holding terminal cp of the second buck converter 142 become high, and both the first and second buck converters 141 and 142 remain in the active state.

[0035] If the start signal Igp is received from the host ECU 190, the start circuit 111 sets the start signal line Sma to active / high level. Figure 3 (Process D92). If the start signal line Sma becomes active / high, the first buck converter 141 starts and outputs a 12-volt output +B. Figure 2 As shown, the 12-volt output +B is also input to the voltage detection terminal Vt of the startup circuit 111. The startup circuit 111 checks the state of the voltage detection terminal Vt at time t2. Figure 3 (Processes D93 and D94) set flag F1 based on the voltage level input to the voltage detection terminal Vt. For example... Figure 4 As shown, if the voltage input to the voltage detection terminal Vt is approximately 12 volts, then the first buck converter 141 is considered to have started normally. Figure 4 As shown, during time t2, flag F1 is set to value 1. On the other hand, if the voltage input to the voltage detection terminal Vt is not approximately 12 volts, for example, around 0 volts, it is considered that the first buck converter 141 has not started normally. Figure 4 As shown, at time t2, flag F1 is set to the value 0.

[0036] The reasons why the voltage input to the voltage detection terminal Vt is not approximately 12 volts could be due to the following: the startup circuit 111 is not outputting a startup signal to the startup signal line Sma; the startup signal line Sma is disconnected; the first buck converter 141 is faulty; or the line from the 12-volt output +B from the first buck converter 141 to the voltage detection terminal Vt is disconnected. In any case, these malfunctions can be identified separately from other malfunctions by setting the confirmation flag F1 to a value of 0 using inspection equipment.

[0037] With the voltage detection terminal Vt at approximately 12 volts and the first buck converter 141 normally started, the 12-volt output +B is supplied to the first power supply terminal +B of FCECU 110, thereby starting FCECU 110. As described above, after starting, FCECU 110 activates the relay action signal Sr. Figure 5 (Step S111). Consequently, the first relay 151 and the second relay 152 actuate, and a holding signal Shd of approximately 12 volts is input to the holding terminal cp of the first buck converter 141. As a result, as... Figure 4 As shown, even after the voltage of the start signal line Sma drops in time t1, the first buck converter 141 remains in operation. The situation where the voltage of the start signal line Sma drops and the operation ceases is called a defect. Figure 2 In the circuit structure shown, the start signal output to the start signal line Sma is used as a single signal. After confirming the 12-volt output +B from the first buck converter 141 in the voltage detection terminal Vt, a hold signal Shd is input to the operation hold terminal cp, thereby continuing the operation of the first buck converter 141. This is because, even if the first buck converter 141 is started by the start signal from the start circuit 111, if the FCECU 110 fails to start due to a broken wire or other malfunction, the first buck converter 141 is kept in operation to prevent unnecessary power consumption or malfunction of auxiliary equipment.

[0038] Return to Figure 5 After processing and outputting the relay action signal Sr (step S111), the value of flag F2, which is non-volatilely stored in memory 113, is set to 0 (step S121). If FCECU 110 terminates normally, as described later, flag F2 is set to 1. Therefore, it is temporarily set to 0 here. Then, the process waits until time t3 (step S125), at which time it is determined whether a 12-volt input is received at the second power input terminal +BP (step S135). As described above, since a holding signal Shd is input to the start terminal wp and the action holding terminal cp of the second buck converter 142, the second buck converter 142 is started by the output of the relay action signal Sr. Therefore, if the second buck converter 142 starts and operates normally, the 12-volt output +BP of the second buck converter 142 is input to the second power input terminal +BP via the normally open contact of the second relay 152. Therefore, if the 12-volt output +BP from the second buck converter 142 is input to the second power supply terminal +BP (step S135: "Yes"), then the value 1 is set in flag F3 (step S141). The period from time t1 to t3 is sufficient as long as it is longer than the time until the second buck converter 142 is started by the relay operation signal Sr and the 12-volt output +BP is established.

[0039] In step S135, if it is determined that the 12-volt output +BP from the second buck converter 142 is not input to the second power terminal +BP (step S135: "No"), then the value of flag F3 is set to 0 (step S142), and the FC start-up interruption process for interrupting the start of the fuel cell 10 is directly performed (step S145), and then this processing routine ends. In the processing up to this point, it has been confirmed that the 12-volt output +BP has been output (…). Figure 3 (Step D94) Therefore, in the FC start-up interruption process, the fuel cell 10, including FC auxiliary machines 133, 134, etc., is first stopped normally. Then, by setting the relay action signal Sr to inactive and disconnecting the holding signal Shd, the operation of the first and second buck converters 141 and 142 is stopped, and as a result, the FCECU 110 also stops. Thus, by setting the value of flag F3 to 0, if the value of flag F3 is read with inspection tools, the malfunction can be separated from other malfunctions and identified as being caused by a fault in the second buck converter 142, poor contact in the normally open setting of the second relay 152, or a break in the line leading to the second power terminal +BP.

[0040] In contrast, assuming the 12-volt output +BP is input to the second power terminal +BP and the value in flag F3 is set to 1 (step S141), the operation control of the fuel cell 10 then begins (step S150). Next, the operation start signal Igp from the host ECU 190 is monitored (step S161), and operation control of the fuel cell 10 continues until the operation start signal Igp disappears. If the operation start signal Igp stops (step S161: "No"), after performing FC stop processing (step S170), the process exits to "END", ending this routine.

[0041] An example of FC stop processing (step S170) is shown below. Figure 6In the FC shutdown process, as shown in the figure, firstly, a predetermined shutdown sequence for the fuel cell 10 is executed (step S171). The predetermined shutdown sequence refers to the actions taken to shut down the oxygen supply system 30 or the fuel gas supply system 40 according to a predetermined sequence of shut-off of auxiliary equipment or valves, etc. After executing these shutdown sequences in sequence, a purging process is performed to prevent freezing or the like during the shutdown of the fuel cell 10 (step S173). Then, the flag F2 is set to the value 1 and stored non-volatilely in the memory 113 (step S175). Finally, the relay operation signal Sr is deactivated (step S177). As a result, the signal Shd is kept off, the first buck converter 141 and the second buck converter 142 stop operating, the 12-volt outputs +B and +BP disappear, power supply to all FC auxiliary machines 131 to 134 or power supply to FCECU 110 stops, and the fuel cell system 200, including the fuel cell drive unit 100, stops operating, except for those directly controlled by the host computer 190.

[0042] Regarding flag F2, it is reset to a value of 0 during the startup of fuel cell 10. Figure 5 (Step S121), set to value 1 at the normal end of the above FC stop process ( Figure 6 (Step S175). Therefore, in addition to normal termination, flag F2 becomes 0, which can separate and distinguish abnormal termination cases. Therefore, when flags F1 and F3 are both 1 and flag F2 is 0, if the FCECU110 terminates abnormally while the first buck converter 141 and the second buck converter 142 are starting normally, the possibility of a high probability of problems such as a broken signal Shd or poor contact of the normally open contact of the first relay 151 can be judged when the FCECU110 starts up again. Figure 5 (Steps S101, S105). Therefore, upon the next startup, even with the 12-volt output +B from the first buck converter 141, the FCECU 110 will not output the relay operation signal Sr. That is, the operation of the first buck converter 141 will not continue due to the holding signal Shd, nor will the second buck converter 142 be started, and no unnecessary operation caused by malfunctions will occur. As a result, even if the holding signal Shd is correctly input into the operation holding terminal cp of the first buck converter 141, the flag F2 corresponds to the second state, which is the supply state of the 12-volt output +B from the first buck converter 141 when the signal of the start signal line Sma is disconnected (defect).

[0043] As explained above, the fuel cell 10 according to this embodiment can separate and determine the following three types of malfunctions.

[0044] [1] The FCECU110 can be judged by the value of the flag F1 to determine the bad condition before starting the first buck converter 141 that cannot be started by the start circuit 111 via the start signal line Sma.

[0045] [2] The faulty situation that the holding signal Shd cannot be maintained normally and the FCECU110 cannot be terminated normally can be determined by the flag F2.

[0046] [3] The value of flag F3 can be used to determine the bad situation where the 12-volt output +BP from the second buck converter 142 cannot be obtained in the control implementation of FCECU110 after the first buck converter 141 is started.

[0047] Furthermore, there is no need to set up a special diagnostic computer or dedicated equipment for detecting malfunctions.

[0048] B. Other implementation methods:

[0049] (1) The fuel cell drive device of the present invention can be implemented, for example, in the following manner. The fuel cell drive device includes: a fuel cell ECU (FCECU) that receives a power supply and controls the operation of a fuel cell including a fuel cell main body and an auxiliary unit; and a buck converter that converts the voltage of a high-voltage battery corresponding to the generation voltage of the fuel cell into a low voltage that serves as the operating voltage of the fuel cell ECU and the auxiliary unit. The fuel cell ECU performs the following control: when receiving an instruction to start operation from the outside, it sets the output of a start signal that causes the buck converter to start outputting a low voltage to be turned on, and receives a low voltage supply from the buck converter; it determines whether the buck converter is operating well based on a first state, which is the received low voltage supply state, and if it is determined that the buck converter is operating normally, it uses the low voltage output to activate a holding circuit that maintains the operation of the buck converter even if the start signal fails; and when the holding circuit is activated, it sets the output of the start signal to be turned off, and records the low voltage supply state from the buck converter at this time as a second state when the operation of the fuel cell is stopped. Thus, the first state can be used to identify and determine the malfunction of the buck converter, and the second state can be used to identify and determine the malfunction of the holding circuit driven by the holding signal. Here, the malfunction of the buck converter or the holding circuit includes not only circuit faults themselves, but also malfunctions such as broken signal lines that cause each circuit to operate.

[0050] (2) In the above structure, when the fuel cell ECU receives the start-of-operation instruction, it can determine whether the holding circuit is functioning properly based on the recorded second state. Thus, even if the fuel cell ECU stops abnormally due to a malfunction in the buck converter, it can still determine the malfunction of the holding circuit based on the recorded second state when it receives the next start-of-operation instruction for the fuel cell. Here, the start-of-operation instruction includes not only start-of-operation instructions from external control devices, such as higher-level control devices on the system, but also readout instructions from the status of the inspection device when connected to it.

[0051] (3) In the structure described in (1) or (2) above, the buck converter can be a first buck converter, the low voltage can be a first low voltage, the auxiliary unit can be a first auxiliary unit, and the fuel cell drive unit can be equipped with a second buck converter. The second buck converter receives a holding signal from the holding circuit and operates, converting the voltage of the high-voltage battery into a second low voltage, which is the operating voltage of the second auxiliary unit, different from that of the first auxiliary unit. The fuel cell ECU receives the second low voltage, determines whether the second buck converter is working properly based on a third state, which is the state of the second low voltage, and outputs the second low voltage to the second auxiliary unit if it is determined that the second buck converter is operating normally. In this way, the buck converter can be divided into two, and the power supply to the corresponding auxiliary unit can be separated. In this way, the maximum output of one buck converter can be reduced, and the range of auxiliary units that stop due to buck converter failure can be divided according to their functions.

[0052] (4) In the structures described in (1) to (3) above, the buck converter may have a holding receiving terminal that maintains its operating state by inputting a low voltage. The holding circuit is a relay driven by the low voltage output, which is a circuit that applies a low voltage to the holding receiving terminal of the buck converter by the relay's pass-through drive. In this way, the holding of the buck converter can be achieved with a simple circuit, and the on / off state of the buck converter can be easily controlled.

[0053] (5) The present invention can also be implemented as a method for sensing abnormal operation of a fuel cell. The method is based on a structure that has a high-voltage battery corresponding to the power generation voltage of the fuel cell to a low-voltage buck converter that serves as the operating voltage of the fuel cell ECU and auxiliary equipment for controlling the operation of the fuel cell, and performs the following steps: when receiving an instruction to start operation from the outside, the output of the start signal that causes the buck converter to start outputting a low voltage is turned on via the fuel cell ECU, and the low voltage supply from the buck converter is received; the operation of the buck converter is determined to be good based on the first state of the received low voltage supply state, and if the buck converter is determined to be operating normally, the holding circuit that maintains the operation of the buck converter by outputting a holding signal even if the start signal fails is activated by using the low voltage output; the output of the start signal is turned off while the holding circuit is activated; when the operation of the fuel cell is stopped, the low voltage supply state from the buck converter, i.e., the second state, is recorded; and when the operation of the fuel cell is started again, the holding of the buck converter based on the recorded second state is determined to be not functioning properly. In this way, without the need for special diagnostic computers, it is easy to detect abnormalities in the structure driving the fuel cell.

[0054] (6) In the above embodiments, a portion of the hardware-implemented structure may be replaced with software. At least a portion of the software-implemented structure can also be implemented using a discrete circuit structure. Furthermore, when part or all of the functionality of the present invention is implemented in software, the software (computer program) can be provided in the form of a computer-readable recording medium. "Computer-readable recording medium" is not limited to portable recording media such as floppy disks or CD-ROMs, but also includes internal storage devices within a computer such as various RAMs or ROMs, or external storage devices fixed to a computer such as hard disks. That is, "computer-readable recording medium" has a broad meaning, including any recording medium capable of permanently rather than temporarily storing data packets.

[0055] This invention is not limited to the embodiments described above, and can be implemented in various structures without departing from its spirit. For example, in order to solve some or all of the above-described problems, or to achieve some or all of the above-described effects, the technical features in the embodiments corresponding to the technical features in the various methods described in the summary section of the invention can be appropriately replaced or combined. Furthermore, if a technical feature is not described as an essential feature in this specification, it can be appropriately deleted.

[0056] Symbol Explanation

[0057] 10-Fuel cell, 20-Fuel cell stack, 21-End plate, 23-Hydrogen supply manifold, 24-Hydrogen exhaust manifold, 25-Fuel cell unit, 30-Oxygen supply system, 31-Pump, 40-Fuel gas supply system, 41-Gas tank, 43-Main shut-off valve, 44-Pressure regulating valve, 45-Injector, 46-Gas-liquid separator, 47-Drain and exhaust valve, 48-Hydrogen supply pipe, 50-Fuel gas recirculation system, 52-Hydrogen pump, 61-Inverter, 70-Motor 71-Pressure sensor, 72-Pressure sensor, 100-Fuel cell drive unit, 111-Starting circuit, 112-CPU, 113-Memory, 120-High voltage battery, 130-Low voltage battery, 131-FC auxiliary machine, 133-FC auxiliary machine, 140-Buck converter, 141-First buck converter, 142-Second buck converter, 151-First relay, 152-Second relay, 190-Host computer, 200-Fuel cell system.

Claims

1. A fuel cell drive device, characterized in that, have: The fuel cell ECU receives the power supply and controls the operation of the fuel cell, including the fuel cell main body and auxiliary equipment; and A buck converter that converts the voltage of a high-voltage battery corresponding to the power generation voltage of the fuel cell into a low voltage that serves as the operating voltage for the fuel cell ECU and the auxiliary equipment. The fuel cell ECU performs the following control: Upon receiving an instruction to start operation from an external source, the output of the start signal that causes the buck converter to output the low voltage is turned on, and the buck converter receives the supply of the low voltage. Based on the first state of the received low voltage supply state, it is determined whether the buck converter is operating properly. If the buck converter is determined to be operating properly, the low voltage output activates a holding circuit that maintains the operation of the buck converter even if the start signal fails. With the holding circuit activated, the output of the start signal is set to disconnect, and the low voltage supply state from the buck converter at this time is recorded as the second state when the operation of the fuel cell is stopped.

2. The fuel cell drive device according to claim 1, characterized in that, When the fuel cell ECU receives the start-of-operation instruction, it determines whether the holding circuit is functioning properly based on the recorded second state.

3. The fuel cell drive device according to claim 1, characterized in that, The buck converter is the first buck converter, the low voltage is the first low voltage, and the auxiliary machine is the first auxiliary machine. The fuel cell drive unit includes a second buck converter that receives a holding signal from the holding circuit and operates accordingly, converting the voltage of the high-voltage battery into a second low voltage, which serves as the operating voltage of a second auxiliary machine, different from that of the first auxiliary machine. The fuel cell ECU receives the second low voltage, determines whether the second buck converter is working properly based on the third state which is the state of the second low voltage, and outputs the second low voltage to the second auxiliary machine if it determines that the second buck converter is operating normally.

4. The fuel cell drive device according to claim 1, characterized in that, The buck converter has a hold-receive terminal that maintains its operating state by inputting the low voltage. The holding circuit is a relay driven by the low voltage output, which is a circuit that applies the low voltage to the holding receiving terminal of the buck converter via the contacts of the relay that become open by the drive.

5. A method for sensing operational anomalies in a fuel cell, characterized in that, Assuming a structure that includes a high-voltage battery corresponding to the fuel cell's power generation voltage, converting it into a low-voltage buck converter that serves as the operating voltage for the fuel cell ECU and auxiliary equipment controlling the operation of the fuel cell, the following steps are performed: Upon receiving an instruction to start operation from an external source, the fuel cell ECU sets the output of the start signal that causes the buck converter to output the low voltage to be turned on, and receives the supply of the low voltage from the buck converter. The operation of the buck converter is determined based on the first state of the received low voltage supply state. If the buck converter is determined to be operating normally, the low voltage output is used to activate the holding circuit that maintains the operation of the buck converter even if the start signal fails. With the holding circuit activated, the output of the start signal is set to disconnect. When the fuel cell operation is stopped, the low voltage supply state from the buck converter, i.e., state 2, is recorded. When the fuel cell starts running again, it is determined, based on the recorded second state, that the holding function of the buck converter based on the holding circuit is not functioning properly.

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