Fuel cell system and control method during startup of fuel cell system

Abstract

Provided is a fuel cell system and a control method during startup of the fuel cell system. In a fuel cell system including a set of a fuel cell stack and an air supply mechanism and a power storage mechanism for supplying power to the air supply mechanism, with multiple sets of the fuel cell stack and the air supply mechanism, and the power storage mechanism supplying power to the multiple air supply mechanisms, it is possible to reduce the peak power consumption of the air supply mechanism. When the first fuel cell set (109a) and the second fuel cell set (109b) of the fuel cell system (300) are started up, after driving either the first air supply mechanism (102a) or the second air supply mechanism (102b), the other air supply mechanism is driven in such a way that the power peak of the other air supply mechanism appears after the output voltage of the fuel cell stack on one side reaches the first output value.

Description

Technical Field

[0001] The present invention relates to a fuel cell system and a control method during startup of the fuel cell system. Background Art

[0002] Conventionally, a fuel cell system having one set of a fuel cell stack and an electric air supply device and one power storage mechanism each has been known ( Figure 1 ). The fuel cell system 100 schematically configured in Figure 1 includes: a fuel cell set 109 including a fuel cell stack 101 and an air supply mechanism 102; a power storage mechanism 103; and a fuel cell protection diode 105. The fuel cell system 100 is connected to an electrical load 107 as a load. At startup of the fuel cell system 100, power is supplied from the power storage mechanism 103 to the air supply mechanism 102, air is supplied from the air supply mechanism 102 to the fuel cell stack 101, and power generation of the fuel cell stack 101 starts. When power generation of the fuel cell stack 101 starts, power generated by power generation of the fuel cell stack 101 is supplied to the air supply mechanism 102.

[0003] A fuel cell system having a plurality of fuel cells is known. Patent Document 1 (Japanese Unexamined Patent Application Publication No. 2020-031030) describes a fuel cell system including: a first fuel cell; a second fuel cell having a maximum output power greater than that of the first fuel cell; and a power generation control unit that controls power generation of the first fuel cell and the second fuel cell according to required power.

[0004] When the required power is less than a first threshold, the power generation control unit of Patent Document 1 causes the first fuel cell to generate power to mainly satisfy the required power by the first fuel cell. When the required power is equal to or greater than a second threshold and less than a third threshold, the power generation control unit causes the second fuel cell to generate power to mainly satisfy the required power by the second fuel cell, the second threshold being equal to or greater than the first threshold, and the third threshold being greater than the second threshold and greater than 50% with respect to the sum of the maximum output power of the first fuel cell and the maximum output power of the second fuel cell. When the required power is equal to or greater than the third threshold, the power generation control unit causes the first fuel cell and the second fuel cell to generate power to satisfy the required power by both the first fuel cell and the second fuel cell.

[0005] When operating a fuel cell system, it is necessary to drive auxiliary machines such as valves within the system. Patent Document 2 (Japanese Patent Application Laid-Open No. 2007-149621) describes a fuel cell system including a fuel cell and a low-voltage power source with a low voltage among secondary batteries having different voltages. When starting up the fuel cell system, the fuel cell system drives or stops a low-voltage auxiliary machine driven by the low-voltage power source according to the condition of the low-voltage power supply system. Summary of the Invention

[0006] Problems to be Solved by the Invention

[0007] In the fuel cell system described in Patent Document 1, the power required to drive the auxiliary machines included in multiple fuel cells also increases, the battery capacity increases, and the system becomes larger. Therefore, it is difficult to stably perform the start-up control of multiple fuel cells and to miniaturize the fuel cell system.

[0008] The fuel cell system described in Patent Document 2 does not start multiple fuel cells, and in the case where the battery deteriorates and the capacity decreases, there may be a start-up delay due to insufficient power.

[0009] When using Figure 1 In the case of the fuel cell system 100 shown, if the fuel cell unit 109 including the fuel cell stack 101 and the air supply mechanism 102 is paralleled, large power can be obtained, but it is necessary to increase the capacity of the power storage mechanism 103 for supplying power to the multiple air supply mechanisms 102 when starting up the multiple fuel cell stacks 101. Therefore, it is impossible to avoid the enlargement of the fuel cell system 100.

[0010] The present invention has been completed in view of such a situation, and an object thereof is to provide a fuel cell system and a control method for starting up the fuel cell system, in a fuel cell system including a unit of a fuel cell stack and an air supply mechanism and a power storage mechanism for supplying power to the air supply mechanism, the unit of the fuel cell stack and the air supply mechanism being multiple, and the power storage mechanism supplying power to the multiple air supply mechanisms, capable of reducing the peak power consumption of the air supply mechanism.

[0011] Means for Solving the Problems

[0012] The fuel cell system and the start-up control method of the fuel cell system of the present invention adopt the following configuration.

[0013] (1) A fuel cell system according to an aspect of the present invention includes: a first fuel cell assembly including a first fuel cell stack and a first air supply mechanism for supplying air to the first fuel cell stack; a second fuel cell assembly including a second fuel cell stack and a second air supply mechanism for supplying air to the second fuel cell stack; a power storage mechanism for supplying power to the first air supply mechanism and the second air supply mechanism connected in electrical parallel; a connection part capable of applying the output voltages of the first fuel cell stack and the second fuel cell stack to the first air supply mechanism and the second air supply mechanism; and a control mechanism for controlling the first fuel cell assembly and the second fuel cell assembly. The first fuel cell stack and the second fuel cell stack are connected to an electrical load. Further, when starting the first fuel cell assembly and the second fuel cell assembly, the control mechanism drives one of the first air supply mechanism and the second air supply mechanism first, and then drives the other air supply mechanism in such a manner that a power peak of the other air supply mechanism appears after the output voltage of the fuel cell stack on the first-driven side reaches a first output value.

[0014] With this configuration, stable startup can be achieved while suppressing the high capacity and large size of the power storage mechanism. In particular, by using the power of the fuel cell stack that has been started first during the driving of the other air supply mechanism, the capacity of the power storage mechanism can be reduced without limitation.

[0015] (2) Based on the above aspect (1), it may further include: a third fuel cell assembly including a third fuel cell stack connected in series with the first fuel cell stack and a third air supply mechanism for supplying air to the third fuel cell stack; and a fourth fuel cell assembly including a fourth fuel cell stack connected in series with the second fuel cell stack and a fourth air supply mechanism for supplying air to the fourth fuel cell stack. The third air supply mechanism and the fourth air supply mechanism may also be connected in electrical parallel with the first air supply mechanism and the second air supply mechanism.

[0016] With this configuration, the output range of the fuel cell system can be expanded while suppressing the high capacity and large size of the power storage mechanism.

[0017] (3) Based on the above aspect (2), the control mechanism may also determine the number of operating fuel cell assemblies based on the required output of the electrical load, and operate at least one fuel cell assembly. After starting at least one fuel cell assembly, the control mechanism may adjust the driving states of the respective air supply mechanisms that supply air to the respective fuel cell stacks in such a manner that the periods when the output voltages of the fuel cell stacks connected in series each reach the first output value are made consistent.

[0018] According to this structure, while suppressing the back electromotive force of the fuel cell stack, it is possible to suppress the high capacity and large size of the power storage mechanism by staggering the peaks of the air supply mechanism.

[0019] (4) Based on the solution in the above (2) or (3), the control mechanism may also adjust the driving state of the air supply mechanism that supplies air to the fuel cell stack when starting the fuel cell assembly according to the remaining capacity of the power storage mechanism.

[0020] According to this structure, by adjusting the height of the peak according to the remaining capacity of the power storage mechanism, it is possible to start the fuel cell system stably.

[0021] (5) Based on the solution in the above (1), it may further include: a first discharge path that discharges hydrogen from the first fuel cell stack; a second discharge path that discharges hydrogen from the second fuel cell stack; a confluence portion of the first discharge path and the second discharge path; a first bypass path that bypasses the first fuel cell stack and supplies the air supplied from the first air supply mechanism to the first discharge path or the confluence portion by switching using a first supply path switching mechanism; and a second bypass path that bypasses the second fuel cell stack and supplies the air supplied from the second air supply mechanism to the second discharge path or the confluence portion by switching using a second supply path switching mechanism. The control mechanism may also operate the first fuel cell assembly based on the required output of the electrical load, and may, when stopping the second fuel cell assembly, start driving the second air supply mechanism after starting to drive the first air supply mechanism and supply air to the confluence portion via the second bypass path.

[0022] According to this structure, it is possible to reliably dilute hydrogen while reducing the load on the air supply mechanism of the operating fuel cell assembly.

[0023] (6) Based on the solution in the above (5), the second air supply mechanism may also be driven at a discharge amount higher than the discharge pressure at the confluence portion accompanying the driving of the first fuel cell assembly.

[0024] According to this structure, it is possible to suppress the backflow in the bypass path.

[0025] (7)On the basis of the solution in (2) above, it may also have: a first discharge path that discharges hydrogen from the first fuel cell stack; a second discharge path that discharges hydrogen from the second fuel cell stack; a third discharge path that discharges hydrogen from the third fuel cell stack; a fourth discharge path that discharges hydrogen from the fourth fuel cell stack; a confluence of the first discharge path, the second discharge path, the third discharge path, and the fourth discharge path; a first bypass path that bypasses the first fuel cell stack by switching the air supplied from the first air supply mechanism using a first supply path switching mechanism and supplies it to the first discharge path or the confluence; a second bypass path that bypasses the second fuel cell stack by switching the air supplied from the second air supply mechanism using a second supply path switching mechanism and supplies it to the second discharge path or the confluence; a third bypass path that bypasses the third fuel cell stack by switching the air supplied from the third air supply mechanism using a third supply path switching mechanism and supplies it to the third discharge path or the confluence; and a fourth bypass path that bypasses the fourth fuel cell stack by switching the air supplied from the fourth air supply mechanism using a fourth supply path switching mechanism and supplies it to the fourth discharge path or the confluence. The control mechanism may also output to operate the first fuel cell set based on the requirements of the electrical load, or may, when stopping the second fuel cell set, the third fuel cell set, and the fourth fuel cell set, after starting the drive of the first air supply mechanism, start the drive of the second air supply mechanism, the third air supply mechanism, and the fourth air supply mechanism, and supply air to the confluence via the second bypass path, the third bypass path, and the fourth bypass path.

[0026] According to this structure, it is possible to reliably dilute hydrogen while reducing the load on the air supply mechanism of the operating fuel cell set.

[0027] (8)On the basis of the solution in (7) above, the second air supply mechanism, the third air supply mechanism, and the fourth air supply mechanism may also be driven at a discharge amount higher than the discharge pressure at the confluence accompanying the drive of the first fuel cell set.

[0028] According to this structure, it is possible to suppress the backflow in the bypass path.

[0029] (9) The control method during startup of a fuel cell system according to an aspect of the present invention is a control method during startup of the following fuel cell system. The fuel cell system includes: a first fuel cell assembly including a first fuel cell stack and a first air supply mechanism for supplying air to the first fuel cell stack; a second fuel cell assembly including a second fuel cell stack and a second air supply mechanism for supplying air to the second fuel cell stack; an electrical load connected to the first fuel cell stack and the second fuel cell stack connected in electrical parallel; a power storage mechanism for supplying power to the first air supply mechanism and the second air supply mechanism connected in electrical parallel; a connection part capable of applying the output voltages of the first fuel cell stack and the second fuel cell stack to the first air supply mechanism and the second air supply mechanism; and a control mechanism for controlling the first fuel cell assembly and the second fuel cell assembly. Among them, during startup of the first fuel cell assembly and the second fuel cell assembly, after driving either the first air supply mechanism or the second air supply mechanism, the other air supply mechanism is driven in such a manner that a power peak of the other air supply mechanism appears after the output voltage of the fuel cell stack on the one side reaches a first output value.

[0030] According to this structure, stable startup can be achieved while suppressing the high capacity and large size of the power storage mechanism. In particular, by using the power of the fuel cell stack that has started up first during the driving of the other air supply mechanism, the capacity of the power storage mechanism can be reduced without limitation.

[0031] (10) Based on the solution in the above (9), it may further include: a third fuel cell assembly including a third fuel cell stack connected in series with the first fuel cell stack and a third air supply mechanism for supplying air to the third fuel cell stack; and a fourth fuel cell assembly including a fourth fuel cell stack connected in series with the second fuel cell stack and a fourth air supply mechanism for supplying air to the fourth fuel cell stack. The third air supply mechanism and the fourth air supply mechanism may also be connected in electrical parallel with the first air supply mechanism and the second air supply mechanism.

[0032] According to this structure, while suppressing the high capacity and large size of the power storage mechanism, the output range of the fuel cell system can be expanded.

[0033] (11)Based on the above solution in (9), the above fuel cell system may further include: a first discharge path that discharges hydrogen from the above first fuel cell stack; a second discharge path that discharges hydrogen from the above second fuel cell stack; a confluence portion of the above first discharge path and the above second discharge path; a first bypass path that supplies the air supplied from the above first air supply mechanism to the above first discharge path or the above confluence portion by switching using a first supply path switching mechanism and bypassing the above first fuel cell stack; and a second bypass path that supplies the air supplied from the above second air supply mechanism to the above second discharge path or the above confluence portion by switching using a second supply path switching mechanism and bypassing the above second fuel cell stack. It is also possible to operate the above first fuel cell set based on the required output of the above electrical load. When the above second fuel cell set is stopped, after starting the drive of the above first air supply mechanism, the drive of the above second air supply mechanism can be started, and air can be supplied to the above confluence portion via the above second bypass path.

[0034] According to this structure, it is possible to reliably dilute hydrogen while reducing the load on the air supply mechanism of the operating fuel cell set.

[0035] (12) Based on the above solution in (10), the fuel cell system may further include: a first discharge path for discharging hydrogen from the first fuel cell stack; a second discharge path for discharging hydrogen from the second fuel cell stack; a third discharge path for discharging hydrogen from the third fuel cell stack; a fourth discharge path for discharging hydrogen from the fourth fuel cell stack; a confluence of the first discharge path, the second discharge path, the third discharge path, and the fourth discharge path; a first bypass path for bypassing the first fuel cell stack and supplying the air supplied from the first air supply mechanism to the first discharge path or the confluence by switching using a first supply path switching mechanism; a second bypass path for bypassing the second fuel cell stack and supplying the air supplied from the second air supply mechanism to the second discharge path or the confluence by switching using a second supply path switching mechanism; a third bypass path for bypassing the third fuel cell stack and supplying the air supplied from the third air supply mechanism to the third discharge path or the confluence by switching using a third supply path switching mechanism; and a fourth bypass path for bypassing the fourth fuel cell stack and supplying the air supplied from the fourth air supply mechanism to the fourth discharge path or the confluence by switching using a fourth supply path switching mechanism. It is also possible to operate the first fuel cell set based on the requirements of the electrical load. When the second fuel cell set, the third fuel cell set, and the fourth fuel cell set are stopped, after starting the drive of the first air supply mechanism, the drive of the second air supply mechanism, the third air supply mechanism, and the fourth air supply mechanism can be started, and air can be supplied to the confluence via the second bypass path, the third bypass path, and the fourth bypass path.

[0036] According to this structure, it is possible to reliably dilute hydrogen while reducing the load on the air supply mechanism of the operating fuel cell set.

[0037] Advantages of the Invention

[0038] According to the above solutions in (1) - (12), it is possible to provide a fuel cell system and a control method for starting the fuel cell system. In a fuel cell system including a pair of a fuel cell stack and an air supply mechanism and a power storage mechanism for supplying power to the air supply mechanism, where there are multiple pairs of the fuel cell stack and the air supply mechanism, and the power storage mechanism supplies power to multiple air supply mechanisms, it is possible to reduce the peak power consumption of the air supply mechanism. Moreover, it is possible to minimize the generation of reverse potential in the stack during startup and minimize the power storage mechanism.

[0039] Therefore, it is possible to reduce the hydrogen concentration in the exhaust without increasing the output of the power storage mechanism. Brief Description of the Drawings

[0040] Figure 1 It is a schematic configuration diagram of an example of a conventional fuel cell system.

[0041] Figure 2 It is a schematic configuration diagram of an example of a fuel cell system according to an embodiment.

[0042] Figure 3 It is a schematic configuration diagram of another example of a fuel cell system according to an embodiment.

[0043] Figure 4 It is a schematic configuration diagram of an example of an auxiliary machine power supply circuit in an example of a fuel cell system according to an embodiment.

[0044] Figure 5 It is a schematic configuration diagram of an example of an auxiliary machine power supply circuit in an example of a fuel cell system according to an embodiment.

[0045] Figure 6 It is a schematic configuration diagram of an example of an auxiliary machine power supply circuit in an example of a fuel cell system according to an embodiment.

[0046] Figure 7 It is a schematic configuration diagram of an example of an auxiliary machine power supply circuit in an example of a fuel cell system according to an embodiment.

[0047] Figure 8 It is a schematic configuration diagram of an example of an auxiliary machine power supply circuit in an example of a fuel cell system according to an embodiment.

[0048] Figure 9 It is a schematic configuration diagram of an example of an auxiliary machine power supply circuit in an example of a fuel cell system according to an embodiment.

[0049] Figure 10 It is a schematic configuration diagram of an example of an auxiliary machine power supply circuit in an example of a fuel cell system according to an embodiment.

[0050] Figure 11 It is a schematic configuration diagram of an example of an auxiliary machine power supply circuit in an example of a fuel cell system according to an embodiment.

[0051] Figure 12 It is a schematic diagram showing the flow of gas at the start of a fuel cell system according to an embodiment.

[0052] Figure 13 It is a table explaining the start-up process of a fuel cell system according to an embodiment.

[0053] Figure 14 It is a table explaining the start-up mode of a fuel cell system according to an embodiment.

[0054] Figure 15 It is a flowchart showing the drive process of a fuel cell system according to an embodiment.

[0055] Figure 16 It is a graph showing the time variation of the voltage of each fuel cell stack when the fuel cell system of the embodiment is started in mode = 1.

[0056] Figure 17 It is a graph showing the time variation of the voltage of each fuel cell stack when the fuel cell system of the embodiment is started in mode = 2.

[0057] Explanation of reference numerals:

[0058] 100... Fuel cell system

[0059] 101... Fuel cell stack

[0060] 101a... First fuel cell stack

[0061] 101b... Second fuel cell stack

[0062] 101c... Third fuel cell stack

[0063] 101d... Fourth fuel cell stack

[0064] 102... Air supply mechanism

[0065] 102a... First air supply mechanism

[0066] 102b... Second air supply mechanism

[0067] 102c... Third air supply mechanism

[0068] 102d... Fourth air supply mechanism

[0069] 103... Power storage mechanism

[0070] 104... Power storage mechanism DCDC converter (BVCU)

[0071] 105... Diode for fuel cell protection

[0072] 106... Fuel cell DCDC converter (FCVCU)

[0073] 107... Electrical load

[0074] 108... Hydrogen supply device

[0075] 108a... First hydrogen supply device

[0076] 108b... Second hydrogen supply device

[0077] 108c... Third hydrogen supply device

[0078] 108d... Fourth hydrogen supply device

[0079] 109... Fuel cell stack

[0080] 109a... First fuel cell stack

[0081] 109b... Second fuel cell stack

[0082] 109c... Third fuel cell stack

[0083] 109d... Fourth fuel cell stack

[0084] 111... Bypass path

[0085] 111a... First bypass path

[0086] 111b... Second bypass path

[0087] 111c... Third bypass path

[0088] 111d... Fourth bypass path

[0089] 112... Supply path switching mechanism

[0090] 112a... First supply path switching mechanism

[0091] 112b... Second supply path switching mechanism

[0092] 112c... Third supply path switching mechanism

[0093] 112d... Fourth supply path switching mechanism

[0094] 113... Auxiliary power supply circuit

[0095] 114... Auxiliary power supply circuit

[0096] 115... Stack discharge path

[0097] 115a... First discharge path

[0098] 115b... Second discharge path

[0099] 115c... Third discharge path

[0100] 115d... Fourth discharge path

[0101] 116... Confluence part

[0102] 200... Fuel cell system

[0103] 300... Fuel cell system

[0104] EX... Stack exhaust Detailed implementation manners

[0105] Hereinafter, with reference to the accompanying drawings, a fuel cell system of the present invention and a control method during startup of the fuel cell system will be described. The fuel cell system of the embodiment is mounted on, for example, an electric device that operates using electric power. In the electric device, for example, there are mobile bodies such as electric vehicles, railway vehicles, flying bodies (such as aircraft, drones, etc.), ships, and robots. The electric device may also include stationary and movable devices.

[0106] An example of the fuel cell system of the embodiment is Figure 2 the fuel cell system 200 shown.

[0107] The fuel cell system 200 includes a first fuel cell stack group including a first fuel cell stack set 109a and a third fuel cell stack set 109c, a second fuel cell stack group including a second fuel cell stack set 109b and a fourth fuel cell stack set 109d, a power storage mechanism 103, and a control device.

[0108] The first fuel cell stack group includes a first fuel cell stack set 109a and a third fuel cell stack set 109c, and the first fuel cell stack 101a and the third fuel cell stack 101c are connected in series.

[0109] The second fuel cell stack group includes a second fuel cell stack set 109b and a fourth fuel cell stack set 109d, and the second fuel cell stack 101b and the fourth fuel cell stack 101d are connected in series.

[0110] The first fuel cell stack group and the second fuel cell stack group are connected in parallel electrically.

[0111] The first fuel cell stack set 109a includes a first fuel cell stack 101a and a first air supply mechanism 102a that supplies air to the first fuel cell stack 101a.

[0112] The second fuel cell stack set 109b includes a second fuel cell stack 101b and a second air supply mechanism 102b that supplies air to the second fuel cell stack 101b.

[0113] The third fuel cell stack set 109c includes a third fuel cell stack 101c and a third air supply mechanism 102c that supplies air to the third fuel cell stack 101c.

[0114] The fourth fuel cell stack set 109d includes a fourth fuel cell stack 101d and a fourth air supply mechanism 102d that supplies air to the fourth fuel cell stack 101d.

[0115] The first fuel cell stack 101a and the third fuel cell stack 101c are electrically connected in series.

[0116] The second fuel cell stack 101b and the fourth fuel cell stack 101d are electrically connected in series.

[0117] The first fuel cell stack 101a and the third fuel cell stack 101c are electrically connected in parallel with the second fuel cell stack 101b and the fourth fuel cell stack 101d.

[0118] The power storage mechanism 103 supplies power to the first air supply mechanism 102a, the second air supply mechanism 102b, the third air supply mechanism 102c, and the fourth air supply mechanism 102d that are electrically connected in parallel.

[0119] Moreover, a connection part capable of applying the output voltage of the fuel cell stack 101 to the air supply mechanism 102 and a control mechanism (not shown) for controlling the fuel cell set 109 are provided.

[0120] The first fuel cell group and the second fuel cell group are connected to the electrical load 107. The electrical load 107 is, for example, a motor for vehicle drive.

[0121] In the fuel cell system of the embodiment, when the first fuel cell set 109a and the second fuel cell set 109b are started, the control mechanism drives either the first air supply mechanism 102a or the second air supply mechanism 102b, and then drives the other air supply mechanism in such a way that the power peak of the other air supply mechanism appears after the output voltage of the fuel cell stack on one side reaches the first output value.

[0122] Preferably, the fuel cell system 200 determines the number of operating fuel cell sets based on the required output of the electrical load through the control mechanism, and after starting at least one fuel cell set and starting at least one fuel cell set, adjusts the driving states of the respective air supply mechanisms that supply air to the respective fuel cell stacks so that the periods when the output voltages of the fuel cell stacks connected in series reach the first output value are the same.

[0123] Preferably, the fuel cell system 200 adjusts the driving state of the air supply mechanism 102 that supplies air to the fuel cell stack 101 when the fuel cell set 109 is started according to the remaining capacity of the power storage mechanism 103 through the control mechanism.

[0124] In the fuel cell system 200, the auxiliary power supply circuit can be configured as follows. In Figures 4 to 11 In, the one related to Figure 2Part 200a associated with the first fuel cell stack of the fuel cell system shown is extracted and shown.

[0125] Figure 4 This is an example where a power storage mechanism DCDC converter (BVCU) 104 is provided.

[0126] Figure 5 This is Figure 4 a modification of the example shown, and is an example where the power storage mechanism 103 is of an insulated type.

[0127] Figure 6 This is an example where a power storage mechanism DCDC converter (BVCU) 104 and a fuel cell DCDC converter (FCVCU) 106 are provided. Compared with Figure 4 , Figure 5 this, the fuel cell protection diode 105 can be omitted.

[0128] Figure 7 This is Figure 6 a modification of the example shown, and is an example where the power storage mechanism 103 is of an insulated type.

[0129] Figure 8 This is an example where neither the power storage mechanism DCDC converter (BVCU) 104 nor the fuel cell DCDC converter (FCVCU) 106 is provided.

[0130] Figure 9 This is an example where a fuel cell DCDC converter (FCVCU) 106 is provided.

[0131] Figure 10 This is an example where a power storage mechanism DCDC converter (BVCU) 104 and a fuel cell DCDC converter (FCVCU) 106 are provided, and the power storage mechanism 103 is of an insulated type.

[0132] Figure 11 This is Figure 10 a modification of the example shown, and is an example where the fuel cell DCDC converter (FCVCU) 106 is of an insulated type.

[0133] As Figure 12As shown, the fuel cell system 200 may also include a first discharge path 115a, a second discharge path 115b, a third discharge path 115c, a fourth discharge path 115d, a confluence part 116, a first bypass path 111a, a second bypass path 111b, a third bypass path 111c, and a fourth bypass path 111d. The first discharge path 115a discharges hydrogen from the first fuel cell stack 101a. The second discharge path 115b discharges hydrogen from the second fuel cell stack 101b. The third discharge path 115c discharges hydrogen from the third fuel cell stack 101c. The fourth discharge path 115d discharges hydrogen from the fourth fuel cell stack 101d. The confluence part 116 is the part where the first, second, third, and fourth discharge paths converge. The first bypass path 111a supplies the air supplied from the first air supply mechanism to the first discharge path or the confluence part by switching using the first supply path switching mechanism 112a while bypassing the first fuel cell stack. The second bypass path 111b supplies the air supplied from the second air supply mechanism to the second discharge path or the confluence part by switching using the second supply path switching mechanism 112b while bypassing the second fuel cell stack. The third bypass path 111c supplies the air supplied from the third air supply mechanism to the third discharge path or the confluence part by switching using the third supply path switching mechanism 112c while bypassing the third fuel cell stack. The fourth bypass path 111d supplies the air supplied from the fourth air supply mechanism to the fourth discharge path or the confluence part by switching using the fourth supply path switching mechanism 112d while bypassing the fourth fuel cell stack. It should be noted that the first bypass path 111a to the fourth bypass path 111d are sometimes collectively referred to as the bypass path 111. The first supply path switching mechanism 112a to the fourth supply path switching mechanism 112d are sometimes collectively referred to as the supply path switching mechanism 112. The first discharge path 115a to the fourth discharge path 115d are sometimes collectively referred to as the stack discharge path 115.

[0134] During the period when the stack is stopped, in order to suppress the deterioration of the stack, hydrogen may be filled into both the anode and the cathode in the stack and sealed. In Figure 12 the example shown, hydrogen is supplied to the first fuel cell stack 101a, the second fuel cell stack 101b, the third fuel cell stack 101c, and the fourth fuel cell stack 101d through the first hydrogen supply device 108a, the second hydrogen supply device 108b, the third hydrogen supply device 108c, and the fourth hydrogen supply device 108d, respectively. In this case, when the fuel cell stack is started, the air supply device 102 discharges to discharge the filled hydrogen. During the exhaust, in order to dilute the hydrogen concentration in the exhaust to a safe concentration or less, a large amount of air needs to be supplied in the air supply device. It should be noted that the first hydrogen supply device 108a to the fourth hydrogen supply device 108d are sometimes collectively referred to as the hydrogen supply device 108.

[0135] In an embodiment, in order to reduce the required power of the air supply mechanism during startup, the air supply amount of the air supply mechanism is suppressed. Although the hydrogen concentration in the exhaust gas increases due to the suppression, by operating the air supply mechanism of the un-started fuel cell stack through a bypass circuit, the hydrogen concentration of the assembly can be efficiently reduced with less power consumption.

[0136] Figure 3 The fuel cell system 300 shown is a fuel cell system obtained by simplifying the fuel cell system of the Figure 2 shown embodiment and being easier to understand. The fuel cell system 300 includes a first fuel cell stack 109a, a second fuel cell stack 109b, a power storage mechanism 103, a connection part, and a control mechanism (not shown). The first fuel cell stack 109a includes a first fuel cell stack 101a and a first air supply mechanism 102a that supplies air to the first fuel cell stack 101a. The second fuel cell stack 109b includes a second fuel cell stack 101b and a second air supply mechanism 102b that supplies air to the second fuel cell stack 101b. The power storage mechanism 103 supplies power to the first air supply mechanism 102a and the second air supply mechanism 102b that are electrically connected in parallel. The connection part can apply the output voltages of the first fuel cell stack 101a and the second fuel cell stack 101b to the first air supply mechanism 102a and the second air supply mechanism 102b. The control mechanism controls the first fuel cell stack 109a and the second fuel cell stack 109b.

[0137] The electrical load 107 is connected to the first fuel cell stack 101a and the second fuel cell stack 101b.

[0138] When the first fuel cell stack 109a and the second fuel cell stack 109b are started up, the control mechanism drives one of the first air supply mechanism 102a and the second air supply mechanism 102b first, and then drives the other air supply mechanism in such a way that the power peak of the other air supply mechanism appears after the output voltage of the fuel cell stack on one side reaches the first output value.

[0139] The second air supply mechanism 102b is driven with a jet volume higher than the discharge pressure at the confluence part accompanying the drive of the first fuel cell stack.

[0140] The control method during startup of the fuel cell system 200 of the embodiment is as Figure 13 and Figure 14 shown, and the startup timing of the fuel cell stacks is staggered. As startup modes, there are modes (MODE)=1 to 3, and the mode is selected according to the Figure 13 process.

[0141] It can also be as Figure 15As shown, the fuel cell stack is started by changing the starting mode according to the degradation state of the fuel cell.

[0142] In the case of implementing the fuel cell system of the embodiment and the control method at the time of starting the fuel cell system, the voltage of each fuel cell stack is Figure 16 , Figure 17 shown.

[0143] Based on the rise in the voltages of the first and third stacks (the first group) due to the start of the stacks in the first stage, the start timing of the stacks in the second stage (the second and fourth stacks) is determined. The amount of stagger in the stack voltage rise timing of the stacks in the first stage is stored in the storage unit in advance, and a time difference is set for the start instruction at the next start, thereby suppressing the occurrence of reverse potential generated between the stacks in series. The same applies to the timing stagger within the series after the second stage. The fluctuation of the start instruction between the stacks is corrected.

[0144] By starting the second group after starting the first group, peak overlap can be avoided and the load on the power storage mechanism (battery) can be reduced.

Claims

1. A fuel cell system, wherein, The fuel cell system includes: A first fuel cell set including a first fuel cell stack and a first air supply mechanism for supplying air to the first fuel cell stack; A second fuel cell set including a second fuel cell stack and a second air supply mechanism for supplying air to the second fuel cell stack; A power storage mechanism for supplying power to the first air supply mechanism and the second air supply mechanism connected in electrical parallel; A connection part capable of applying the output voltages of the first fuel cell stack and the second fuel cell stack to the first air supply mechanism and the second air supply mechanism; And A control mechanism for controlling the first fuel cell set and the second fuel cell set, The first fuel cell stack and the second fuel cell stack are connected to an electrical load, and When starting the first fuel cell set and the second fuel cell set when hydrogen is filled and sealed in the first fuel cell stack and the second fuel cell stack, after driving the first air supply mechanism to discharge the hydrogen filled in the first fuel cell stack and reaching the maximum power consumption at startup, the second air supply mechanism is driven in such a way that the maximum power consumption at startup of the second air supply mechanism for discharging the hydrogen filled in the second fuel cell stack appears after the output voltage of the first fuel cell stack reaches the second-stage startup threshold voltage.

2. The fuel cell system according to claim 1, wherein, The fuel cell system further includes: A third fuel cell set including a third fuel cell stack connected in series with the first fuel cell stack and a third air supply mechanism for supplying air to the third fuel cell stack; and A fourth fuel cell set including a fourth fuel cell stack connected in series with the second fuel cell stack and a fourth air supply mechanism for supplying air to the fourth fuel cell stack, The third air supply mechanism and the fourth air supply mechanism are connected in electrical parallel with the first air supply mechanism and the second air supply mechanism.

3. The fuel cell system according to claim 2, wherein, The control mechanism determines the number of fuel cell sets to be operated based on the required output of the electrical load and operates at least one fuel cell set, After the start of at least one fuel cell set, the driving states of the respective air supply mechanisms for supplying air to the respective fuel cell stacks are adjusted so that the periods in which the output voltages of the fuel cell stacks connected in series reach the first output value are the same.

4. The fuel cell system according to claim 2 or 3, wherein, The control mechanism adjusts the driving state of the air supply mechanism for supplying air to the fuel cell stack at the start of the fuel cell set according to the remaining capacity of the power storage mechanism.

5. The fuel cell system according to claim 1, wherein, The fuel cell system further includes: A first discharge path for discharging hydrogen from the first fuel cell stack; A second discharge path for discharging hydrogen from the second fuel cell stack; A confluence part of the first discharge path and the second discharge path; A first bypass path for supplying the air supplied from the first air supply mechanism to the first discharge path or the confluence part by switching using a first supply path switching mechanism while bypassing the first fuel cell stack; And A second bypass passage that supplies the air supplied from the second air supply mechanism to the second discharge passage or the confluence part by switching using a second supply passage switching mechanism while bypassing the second fuel cell stack. Based on the requirement of the electrical load, the control mechanism outputs to operate the first fuel cell set. When the second fuel cell set is stopped, after starting to drive the first air supply mechanism, the control mechanism starts to drive the second air supply mechanism and supplies air to the confluence part via the second bypass passage.

6. The fuel cell system according to claim 5, wherein, The second air supply mechanism is driven with an ejection amount higher than the discharge pressure at the confluence part accompanying the driving of the first fuel cell set.

7. The fuel cell system according to claim 2, wherein, The fuel cell system further includes: A first discharge passage that discharges hydrogen from the first fuel cell stack. A second discharge passage that discharges hydrogen from the second fuel cell stack. A third discharge passage that discharges hydrogen from the third fuel cell stack. A fourth discharge passage that discharges hydrogen from the fourth fuel cell stack. A confluence part of the first discharge passage, the second discharge passage, the third discharge passage, and the fourth discharge passage. A first bypass passage that supplies the air supplied from the first air supply mechanism to the first discharge passage or the confluence part by switching using a first supply passage switching mechanism while bypassing the first fuel cell stack. A second bypass passage that supplies the air supplied from the second air supply mechanism to the second discharge passage or the confluence part by switching using a second supply passage switching mechanism while bypassing the second fuel cell stack. A third bypass passage that supplies the air supplied from the third air supply mechanism to the third discharge passage or the confluence part by switching using a third supply passage switching mechanism while bypassing the third fuel cell stack. And A fourth bypass passage that supplies the air supplied from the fourth air supply mechanism to the fourth discharge passage or the confluence part by switching using a fourth supply passage switching mechanism while bypassing the fourth fuel cell stack. Based on the requirement of the electrical load, the control mechanism outputs to operate the first fuel cell set. When the second fuel cell set, the third fuel cell set, and the fourth fuel cell set are stopped, after starting to drive the first air supply mechanism, the control mechanism starts to drive the second air supply mechanism, the third air supply mechanism, and the fourth air supply mechanism and supplies air to the confluence part via the second bypass passage, the third bypass passage, and the fourth bypass passage.

8. The fuel cell system according to claim 7, wherein, The second air supply mechanism, the third air supply mechanism, and the fourth air supply mechanism are driven with ejection amounts higher than the discharge pressure at the confluence part accompanying the driving of the first fuel cell set.

9. A control method for starting a fuel cell system, the fuel cell system comprising: A first fuel cell assembly including a first fuel cell stack and a first air supply mechanism for supplying air to the first fuel cell stack; A second fuel cell assembly including a second fuel cell stack and a second air supply mechanism for supplying air to the second fuel cell stack; An electrical load that is connected to the first fuel cell stack and the second fuel cell stack connected in electrical parallel. A power storage mechanism that supplies power to the first air supply mechanism and the second air supply mechanism connected in electrical parallel. A connection part that can apply the output voltages of the first fuel cell stack and the second fuel cell stack to the first air supply mechanism and the second air supply mechanism. And A control mechanism that controls the first fuel cell set and the second fuel cell set, wherein, when starting the first fuel cell set and the second fuel cell set with hydrogen filled and sealed in the first fuel cell stack and the second fuel cell stack, after driving the first air supply mechanism to discharge the hydrogen filled in the first fuel cell stack and reaching the maximum power consumption at startup, the second air supply mechanism is driven in such a way that the maximum power consumption at startup of the second air supply mechanism for discharging the hydrogen filled in the second fuel cell stack appears after the output voltage of the first fuel cell stack reaches the second stage startup threshold voltage.

10. The control method for starting a fuel cell system according to claim 9, wherein, The fuel cell system further includes: a third fuel cell set including a third fuel cell stack connected in series with the first fuel cell stack and a third air supply mechanism for supplying air to the third fuel cell stack; and a fourth fuel cell set including a fourth fuel cell stack connected in series with the second fuel cell stack and a fourth air supply mechanism for supplying air to the fourth fuel cell stack, wherein the third air supply mechanism and the fourth air supply mechanism are electrically connected in parallel with the first air supply mechanism and the second air supply mechanism.

11. The control method for starting a fuel cell system according to claim 9, wherein, The fuel cell system further includes: a first discharge path that discharges hydrogen from the first fuel cell stack; a second discharge path that discharges hydrogen from the second fuel cell stack; a confluence of the first discharge path and the second discharge path; a first bypass path that supplies the air supplied from the first air supply mechanism to the first discharge path or the confluence by switching using a first supply path switching mechanism to bypass the first fuel cell stack; and a second bypass path that supplies the air supplied from the second air supply mechanism to the second discharge path or the confluence by switching using a second supply path switching mechanism to bypass the second fuel cell stack, Based on the required output of the electrical load, the first fuel cell set is operated. When the second fuel cell set is stopped, after starting to drive the first air supply mechanism, the driving of the second air supply mechanism is started, and air is supplied to the confluence via the second bypass path.

12. The control method for starting a fuel cell system according to claim 10, wherein, The fuel cell system further includes: a first discharge path that discharges hydrogen from the first fuel cell stack; a second discharge path that discharges hydrogen from the second fuel cell stack; a third discharge path that discharges hydrogen from the third fuel cell stack; a fourth discharge path that discharges hydrogen from the fourth fuel cell stack; a confluence of the first discharge path, the second discharge path, the third discharge path, and the fourth discharge path; a first bypass path that supplies the air supplied from the first air supply mechanism to the first discharge path or the confluence by switching using a first supply path switching mechanism to bypass the first fuel cell stack; a second bypass path that supplies the air supplied from the second air supply mechanism to the second discharge path or the confluence by bypassing the second fuel cell stack; A third bypass passage that supplies the air supplied from the third air supply mechanism to the third discharge passage or the confluence portion by switching using a third supply passage switching mechanism while bypassing the third fuel cell stack; and A fourth bypass passage that supplies the air supplied from the fourth air supply mechanism to the fourth discharge passage or the confluence portion by switching using a fourth supply passage switching mechanism while bypassing the fourth fuel cell stack, Based on the required output of the electrical load, the first fuel cell set is operated, and when the second fuel cell set, the third fuel cell set, and the fourth fuel cell set are stopped, after starting the drive of the first air supply mechanism, the drive of the second air supply mechanism, the third air supply mechanism, and the fourth air supply mechanism is started, and air is supplied to the confluence portion via the second bypass passage, the third bypass passage, and the fourth bypass passage.

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