fuel cell system

Abstract

A fuel cell system capable of reducing the inrush current flowing through a capacitor included in a fuel cell. [Solution] A fuel cell system comprising a fuel cell including a first capacitor, a storage battery, an electrical path between the fuel cell and the storage battery, and at least one charging circuit provided in the electrical path, wherein the charging circuit includes a first current path in which a first switch is provided, and a second current path in which a resistor connected in parallel to the first switch is provided, and wherein the first capacitor is charged with current flowing through the second current path before the first switch is turned on.

Description

[Technical Field]

[0001] The present disclosure relates to fuel cell systems. [Background technology]

[0002] BACKGROUND ART Conventionally, in a power generation system using a fuel cell as a power generation device, a technique for suppressing an inrush current flowing in a capacitor provided at the input section of a power conditioner is known (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2013-078183 Summary of the Invention [Problem to be solved by the invention]

[0004] The fuel cell may include a capacitor, and in this case, when the fuel cell is connected to an electrical circuit, an inrush current may flow from the electrical circuit to the capacitor.

[0005] The present disclosure provides a fuel cell system capable of reducing the inrush current flowing through a capacitor included in the fuel cell. [Means for solving the problem]

[0006] As one aspect of the present disclosure, a fuel cell including a first capacitor; A storage battery and an electrical path between the fuel cell and the storage battery; At least one charging circuit provided in the electrical path; The charging circuit includes a first current path in which a first switch is provided, and a second current path in which a resistor connected in parallel to the first switch is provided, and the first capacitor is charged with a current flowing through the second current path before the first switch is turned on. [Effects of the Invention]

[0007] According to the present disclosure, it is possible to provide a fuel cell system that can reduce the inrush current flowing through a capacitor included in a fuel cell. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a diagram showing an example of the configuration of a fuel cell system according to a first embodiment. [Figure 2] FIG. 10 is a diagram showing an example of the configuration of a fuel cell system according to a second embodiment. [Figure 3] FIG. 10 is a diagram showing an example of the configuration of a fuel cell system according to a third embodiment. [Figure 4] FIG. 10 is a diagram showing an example of the configuration of a fuel cell system according to a fourth embodiment. [Figure 5] FIG. 10 is a diagram showing an example of the configuration of a fuel cell system according to a fifth embodiment. [Figure 6] 10 is a flowchart illustrating an example of a control process related to initial charging. [Figure 7] FIG. 10 is a diagram illustrating an example of initial charging completion determination. [Figure 8] FIG. 10 is a diagram illustrating an example of initial charging completion determination. [Figure 9] FIG. 10 is a diagram showing an example of a start-up process (step S50) of the fuel cell and the inverter. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, several embodiments will be described with reference to the drawings.

[0010] <Configuration example of fuel cell system according to the first embodiment> Fig. 1 is a diagram showing an example of the configuration of a fuel cell system according to the first embodiment. The fuel cell system 101 shown in Fig. 1 is a power supply system that includes a fuel cell 40 and a storage battery 50 and is capable of supplying power output from at least one of the fuel cell 40 and the storage battery 50 to a load 20. The fuel cell system 101 includes the fuel cell 40, the storage battery 50, the load 20, an electric circuit 10, circuit breakers 80a, 80b, and 80c, a control device 60, and a charging circuit 70.

[0011] The fuel cell 40 generates electricity through a chemical reaction between hydrogen supplied from the fuel system and oxygen contained in the air supplied from the air supply system. The fuel cell 40 is electrically connected to the electrical circuit 10. The fuel cell 40 may be a unit including a fuel cell module 43 and auxiliary equipment 44. The auxiliary equipment 44 is operated by the power supplied from the electrical circuit 10.

[0012] The fuel cell module 43 receives a fuel supply and generates electricity. The fuel cell module 43 includes, for example, a fuel cell stack that generates electricity through a chemical reaction between hydrogen supplied from a fuel system and oxygen contained in air supplied from an air supply system. The fuel cell stack has a stack structure in which multiple cells are stacked. The fuel cell stack is, for example, a polymer electrolyte fuel cell (PEFC). However, the fuel cell stack may also be another type of fuel cell, such as a phosphoric acid fuel cell (PAFC), a solid oxide fuel cell (SOFC), or a molten carbonate fuel cell (MCFC).

[0013] The fuel cell module 43 may include an air compressor that compresses air supplied from an air supply system and supplies it to the fuel cell stack, a coolant pump that circulates coolant between the heat exchanger and the fuel cell stack, and the like.

[0014] The fuel cell module 43 may include a converter 42 that boosts the voltage output from the fuel cell stack. The converter 42 outputs DC power with a voltage higher than the voltage output from the fuel cell stack to the outside of the fuel cell module 43. An output terminal of the converter 42 is electrically connected to the electric circuit 10.

[0015] The fuel cell module 43 includes an output capacitor 41 electrically connected to the electric circuit 10. The output capacitor 41 is, for example, a capacitive element provided at the output portion of the converter 42, and smoothes the output voltage of the converter 42. The output capacitor 41 is an example of a first capacitor included in the fuel cell.

[0016] The auxiliary equipment 44 is a device for operating the fuel cell module 43, and assists the power generation operation of the fuel cell module 43. The auxiliary equipment 44 includes, for example, a fuel system or a purge system.

[0017] The fuel system supplies fuel such as hydrogen to the fuel cell module 43. The fuel system includes a fuel pipe that supplies fuel such as hydrogen to the fuel cell module 43, and a fuel valve provided in the fuel pipe. The fuel valve operates using power supplied from the electrical circuit 10 or a power supply system (not shown). The opening and closing of the fuel valve is controlled by the control device 60. When the fuel valve is open, fuel such as hydrogen is supplied to the fuel cell module 43, and when the fuel valve is closed, the supply of fuel such as hydrogen to the fuel cell module 43 is stopped.

[0018] The purge system supplies an inert gas such as nitrogen to the fuel system. The purge system includes a purge pipe that supplies the inert gas such as nitrogen to the fuel pipe of the fuel system, and a purge valve provided in the purge pipe. The purge valve operates using power supplied from an electric circuit 10 or a power supply system (not shown). The opening and closing of the purge valve is controlled by a control device 60. When the purge valve is open, the inert gas such as nitrogen is supplied to the fuel pipe of the fuel system, and when the purge valve is closed, the supply of the inert gas such as nitrogen to the fuel pipe is stopped.

[0019] The auxiliary device 44 may include a converter 45 that converts the DC input from the electric circuit 10. The converter 45 is a DC / AC converter that converts the DC voltage input from the electric circuit 10 into an AC voltage, or a DC / DC converter that converts the DC voltage input from the electric circuit 10 into a DC voltage. The converter 45 converts the DC power input from the electric circuit 10 and supplies the converted AC power or DC power to electrically driven devices (e.g., a fuel valve, a purge valve, etc.) in the auxiliary device 44. An input terminal of the converter 45 is electrically connected to the electric circuit 10.

[0020] The auxiliary device 44 includes an input capacitor 46 electrically connected to the electric circuit 10. The input capacitor 46 is, for example, a capacitive element provided at the input portion of the converter 45, and smoothes the input voltage of the converter 45. The input capacitor 46 is an example of a first capacitor included in the fuel cell.

[0021] The load 20 is a device that operates by receiving power from the electric circuit 10, and is electrically connected to the electric circuit 10. Examples of the load 20 include a load device (such as a resistive load) that consumes DC power from the electric circuit 10, a DC / DC converter that converts the DC from the electric circuit 10 into DC and outputs it, and an inverter (DC / AC converter) that converts the DC from the electric circuit 10 into AC.

[0022] The inverter is a power conversion device electrically connected to the electric circuit 10. The inverter converts DC power input from the electric circuit 10 into AC power, and outputs the converted AC power to the outside of the inverter.

[0023] For example, when the power system is operating normally, the inverter is connected to the power system wires and transmits and receives power between the power system and the electric circuit 10. In the event of an abnormality such as a power outage in the power system, the inverter is disconnected from the power system wires by a system switch. When disconnected from the wires by the system switch, the inverter operates independently, for example, by reverse-converting power obtained from the fuel cell 40 or the storage battery 50 via the electric circuit 10 and supplying it to a load device (not shown), or by stopping its own operation. A specific example of a system switch is a system circuit breaker.

[0024] The inverter converts the DC of the electric circuit 10 into AC of a predetermined voltage and frequency and outputs the converted AC. For example, the inverter is a power conditioner (PCS: Power Conditioning System) including an inverter circuit 22 that converts the DC into three-phase AC of a predetermined voltage and frequency.

[0025] The load 20 includes an input capacitor 21 electrically connected to the electric circuit 10. The input capacitor 21 is, for example, a capacitive element provided at the input portion of the inverter circuit 22, and smoothes the input voltage of the inverter circuit 22. The input capacitor 21 is an example of a second capacitor included in the load.

[0026] The storage battery 50 is a secondary battery electrically connected to the electrical circuit 10. The storage battery 50 can discharge power to the outside of the fuel cell system 101 via an inverter (load 20), and can also charge (store) power supplied from the fuel cell 40 via the electrical circuit 10. The storage battery 50 is, for example, a capacitor such as a lithium ion capacitor (LIC). The storage battery 50 may be a storage battery such as a lithium ion battery with a liquid electrolyte or an all-solid-state battery with a solid electrolyte. The storage battery 50 is electrically connected to the load 20 and the fuel cell 40 via the electrical circuit 10.

[0027] The number of storage batteries 50 may be one or more. The storage batteries 50 may be a plurality of secondary batteries connected in parallel to the electric circuit 10. The storage batteries 50 may include a plurality of secondary batteries connected in series.

[0028] The electric circuit 10 includes a pair of DC lines (a positive line and a negative line) that electrically connect the fuel cell 40, the storage battery 50, and the load 20. The electric circuit 10 includes a DC link 12 to which the fuel cell 40, the storage battery 50, and the load 20 are electrically connected in common.

[0029] The circuit breakers 80, 80a, and 80c each automatically or manually interrupt the electric circuit 10. The circuit breakers 80, 80a, and 80c may interrupt the electric circuit 10 in accordance with an interruption signal from the control device 60. A specific example of the circuit breaker 80 is a molded case circuit breaker that protects the electric circuit 10 from an abnormal current by interrupting the electric circuit 10 upon detecting an abnormal current flowing through the electric circuit 10.

[0030] The circuit breaker 80 is a device that disconnects the storage battery 50 from the electric circuit 10, and interrupts the electric circuit 10 between the DC link 12 and the storage battery 50. The circuit breaker 80a is a device that disconnects the fuel cell 40 from the electric circuit 10, and interrupts the electric circuit 10 between the DC link 12 and the fuel cell 40. The circuit breaker 80c is a device that disconnects the load 20 from the electric circuit 10, and interrupts the electric circuit 10 between the DC link 12 and the load 20.

[0031] The control device 60 controls the fuel cell system 101. For example, the control device 60 controls the inverter (load 20), the fuel cell 40 (fuel cell module 43 and auxiliary equipment 44), and the charging circuit 70. The control device 60 is, for example, a PLC (Programmable Logic Controller).

[0032] The control device 60 may include electronic circuits such as a central processing unit (CPU), a field programmable gate array (FPGA), or an application specific integrated circuit (ASIC). The control device 60 may be a computer having a memory and a processor. The control device 60 performs the various control operations described in this specification by executing a program such as instruction code stored in the memory, or by being a circuit designed for a specific application.

[0033] When the load 20 is an inverter, the control device 60 may have a function of detecting whether the power grid is normal or abnormal based on, for example, a detection result of the voltage of the power grid externally connected to the inverter via a grid switch. The control device 60 may also detect the presence or absence of an abnormality in the power grid using other known detection methods. For example, when the grid switch is in an on state and the control device 60 detects that the power grid is in an abnormal state such as a power outage, the control device 60 switches the grid switch from on to off. For example, when the grid switch is in an off state and the control device 60 detects that the power grid is in a normal state (for example, the power grid has recovered from an abnormality such as a power outage), the control device 60 switches the grid switch from off to on.

[0034] For example, when the grid switch is on (i.e., when the power grid is normal), the control device 60 operates the inverter (load 20) in a grid-connected operation mode in which power is exchanged between the power grid and the electric circuit 10. For example, when the grid switch is off (i.e., when the power grid is abnormal, such as a power outage), the control device 60 operates the inverter (load 20) in an independent operation mode in which power obtained from the fuel cell 40 or the storage battery 50 via the electric circuit 10 is reverse-converted and supplied to an external load device. When the grid switch is off (i.e., when the power grid 1 is abnormal, such as a power outage), the control device 60 may stop the operation of the inverter (load 20). At this time, the control device 60 may stop the fuel cell 40. For example, the control device 60 may stop the auxiliary system and the fuel cell 40 simultaneously or sequentially.

[0035] The control device 60 may perform processing (start-up processing) to start the fuel cell system 101 in a stopped state, or may perform processing (stop processing) to stop the fuel cell system 101 in an operating state. Starting up the fuel cell system 101 means starting up the auxiliary systems of the fuel cell system 101 when the fuel cell system 101 is in a stopped state, and starting the fuel cell 40 while the auxiliary systems are operating. Stopping the fuel cell system 101 means stopping the operation of the auxiliary systems and the fuel cell 40 simultaneously or sequentially.

[0036] The charging circuit 70 is one of the charging circuits provided in the electric circuit 10, and is a circuit that prevents an inrush current from flowing in the electric circuit 10. The charging circuit 70 is provided between the DC link 12 and the storage battery 50.

[0037] Immediately after starting up the fuel cell 40, the smoothing output capacitor 41, which is located on the DC side of the fuel cell 40, or the smoothing input capacitor 46, which is located on the DC side of the auxiliary equipment 44, is not charged. At this time, when the circuit breaker 80 and the circuit breaker 80a are turned on to electrically connect the fuel cell 40 and the storage battery 50 through the electrical circuit 10, an extremely large current (inrush current) flows through the output capacitor 41 or the input capacitor 46 through the electrical circuit 10. The inrush current may cause equipment failure in the fuel cell system 101 or erroneous detection of an abnormality due to a voltage drop in the electrical circuit 10.

[0038] Similarly, immediately after the load 20 is started, the smoothing input capacitor 21 arranged on the DC side of the load 20 is not charged. At this time, when the circuit breaker 80 and the circuit breaker 80c are turned on to electrically connect the load 20 and the storage battery 50 through the electric circuit 10, an extremely large current (inrush current) flows through the input capacitor 21 through the electric circuit 10. The inrush current may cause equipment failure in the fuel cell system 101 or erroneous detection of an abnormality due to a voltage drop in the electric circuit 10.

[0039] In the fuel cell system 101 according to the first embodiment, the charging circuit 70 includes a first current path 77 provided with a first switch 71, and a second current path 78 provided with a resistor 76 connected in parallel to the first switch 71. In this example, the charging circuit 70 includes a second switch 72 connected in series to the resistor 76, and when the second switch 72 is turned on, a current flows through the second current path 78.

[0040] Immediately after the fuel cell 40 is started up from a stopped state, the control device 60 turns the first switch 71 off and the second switch 72 on.

[0041] Based on a switch control signal from the control device 60, the charging circuit 70 charges the output capacitor 41 and the input capacitor 46 with a current flowing through the second current path 78, and then turns on the first switch 71. As a result, due to the inrush current suppression effect of the resistor 76 arranged in the second current path 78, a relatively small current flows from the storage battery 50 to the fuel cell 40 via the electrical circuit 10, and the output capacitor 41 and the input capacitor 46 are relatively slowly charged (pre-charged). For example, the control device 60 turns on the first switch 71 at a timing when it can be determined that the output capacitor 41 and the input capacitor 46 have been sufficiently charged. Therefore, even if the fuel cell 40 and the storage battery 50 are electrically connected to each other via the electrical circuit 10 by turning on the circuit breaker 80 and the circuit breaker 80a, the inrush current flowing through the output capacitor 41 and the input capacitor 46 is reduced.

[0042] Similarly, based on a switch control signal from the control device 60, the charging circuit 70 charges the input capacitor 21 with a current flowing through the second current path 78 and then turns on the first switch 71. As a result, due to the inrush current suppression effect of the resistor 76 arranged in the second current path 78, a relatively small current flows from the storage battery 50 to the load 20 via the electrical circuit 10, and the input capacitor 21 is relatively slowly charged (pre-charged). For example, the control device 60 turns on the first switch 71 at a timing when it can be determined that the input capacitor 21 has been sufficiently charged. Therefore, even if the load 20 and the storage battery 50 are electrically connected to each other via the electrical circuit 10 by turning on the circuit breaker 80 and the circuit breaker 80c, the inrush current flowing through the input capacitor 21 is reduced.

[0043] Since the inrush current is reduced, the risk of equipment failure in the fuel cell system 101 and erroneous detection of an abnormality due to a voltage drop in the electric circuit 10 is reduced.

[0044] The control device 60 turns off the second switch 72 provided in the second current path 78 after turning on the first switch 71. This cuts off the second current path 78, and the continuation of the current suppression by the resistor 76 is discontinued.

[0045] The first switch 71 and the second switch 72 open and close their contacts in accordance with a switch control signal from the control device 60. Examples of the first switch 71 and the second switch 72 include an electromagnetic contactor and a relay. The resistor 76 may be a resistor that can be used for other purposes, such as a thermistor, as long as it is a resistor that consumes power.

[0046] <Configuration example of fuel cell system according to the second embodiment> 2 is a diagram showing an example of the configuration of a fuel cell system according to a second embodiment. In the second embodiment, the description of the configuration, actions, and effects similar to those of the first embodiment will be omitted by referencing the above description. The fuel cell system 102 shown in FIG. 2 differs from the fuel cell system 101 according to the first embodiment in that there are multiple fuel cells 40 and multiple loads 20.

[0047] 2, the fuel cell system 102 includes a plurality of fuel cells 40 (two fuel cells 40a and 40b in this example) electrically connected to an electric circuit 10, and a load 20 (two loads 20c and 20d in this example) electrically connected to the electric circuit 10. The number of either the fuel cells 40 or the loads 20 may be one. The plurality of fuel cells 40 may have the same configuration. The plurality of loads 20 may have the same configuration.

[0048] A fuel cell system 102 according to the second embodiment is configured by adding circuit breakers 80b and 80d to the fuel cell system 101. The circuit breaker 80b is a device that disconnects the fuel cell 40b from the electric circuit 10, and breaks the electric circuit 10 between the DC link 12 and the fuel cell 40b. The circuit breaker 80d is a device that disconnects the load 20d from the electric circuit 10, and breaks the electric circuit 10 between the DC link 12 and the load 20d.

[0049] The DC link 12 is electrically connected to the capacitors (output capacitor 41 and input capacitor 46) of the plurality of fuel cells 40a, 40b, and is also electrically connected to the capacitors (input capacitor 21) of the plurality of loads 20c, 20d.

[0050] Based on a switch control signal from the control device 60, the charging circuit 70 charges the output capacitor 41 and the input capacitor 46 with the current flowing through the second current path 78, and then turns on the first switch 71. Therefore, even if the fuel cell 40b and the storage battery 50 are electrically connected to each other through the electrical circuit 10 by turning on the circuit breaker 80 and the circuit breaker 80b, the inrush current flowing through the output capacitor 41 and the input capacitor 46 of the fuel cell 40b is reduced. Similarly, even if the load 20d and the storage battery 50 are electrically connected to each other through the electrical circuit 10 by turning on the circuit breaker 80 and the circuit breaker 80d, the inrush current flowing through the input capacitor 21 of the load 20d is reduced.

[0051] <Configuration example of fuel cell system according to the third embodiment> FIG. 3 is a diagram showing an example of the configuration of a fuel cell system according to a third embodiment. In the third embodiment, the description of the configuration, operations, and effects similar to those of the above-described embodiments will be omitted by incorporating the above descriptions. The fuel cell system 103 shown in FIG. 3 differs from the fuel cell system 102 according to the second embodiment in that the charging circuit 70 includes multiple charging circuits that individually charge the capacitors of the fuel cells 40a and 40b. The fuel cell system 103 shown in FIG. 3 differs from the fuel cell system 102 according to the second embodiment in that the charging circuit 70 includes multiple charging circuits that individually charge the capacitors of the loads 20c and 20d.

[0052] 3, charging circuit 70a is provided between fuel cell 40a and DC link 12. Charging circuit 70b is provided between fuel cell 40b and DC link 12. By providing a charging circuit for each fuel cell, it is possible to individually charge the capacitors of the multiple fuel cells. Charging circuits 70a and 70b may be the same as charging circuit 70.

[0053] 3, a charging circuit 70c is provided between a load 20c and the DC link 12. A charging circuit 70d is provided between a load 20d and the DC link 12. By providing a charging circuit for each load, it is possible to individually charge the capacitors of multiple loads. The charging circuits 70c and 70d may be the same as the charging circuit 70.

[0054] <Configuration example of fuel cell system according to the fourth embodiment> Fig. 4 is a diagram showing an example of the configuration of a fuel cell system according to a fourth embodiment. In the fourth embodiment, the description of the configuration, operation, and effects similar to those of the above-mentioned embodiments will be omitted by citing the above description. The fuel cell system 104 shown in Fig. 4 differs from the fuel cell system 103 according to the third embodiment in that it does not have a charging circuit 70 provided between the DC link 12 and the storage battery 50.

[0055] 4, even if the charging circuit 70 is not provided, by providing a charging circuit for each fuel cell, the capacitors of the fuel cells can be charged individually. Similarly, by providing a charging circuit for each load, the capacitors of the loads can be charged individually.

[0056] <Configuration example of fuel cell system according to the fifth embodiment> FIG. 5 is a diagram showing an example of the configuration of a fuel cell system according to a fifth embodiment. In the fifth embodiment, the description of the configuration, operations, and effects similar to those of the above-described embodiments will be omitted by incorporating the above descriptions. The fuel cell system 105 shown in FIG. 5 differs from the fuel cell system 104 according to the fourth embodiment in that the charging circuit 70 includes a common charging circuit 70e that individually charges each capacitor of the multiple fuel cells 40a, 40b. The fuel cell system 105 shown in FIG. 5 differs from the fuel cell system 104 according to the fourth embodiment in that the charging circuit 70 includes a common charging circuit 70f that individually charges each capacitor of the multiple loads 20c, 20d.

[0057] The charging circuit 70e includes a plurality of first current paths 77 used separately by the plurality of fuel cells 40a, 40b, a second current path 78 shared by the plurality of fuel cells 40a, 40b, and switches 71a, 71b, 73a, 73b, 74a, and 74b.

[0058] Based on a switch control signal from the control device 60, the charging circuit 70e turns on switches 73b, 72, and 74b and turns off switches 71b, 73a, and 74a, thereby charging the capacitors (output capacitor 41 and input capacitor 46) of the fuel cell 40b with the current flowing through the second current path 78. Based on the switch control signal from the control device 60, the charging circuit 70e charges the capacitor of the fuel cell 40b and then turns on switch 71b. This reduces the inrush current flowing through the output capacitor 41 and input capacitor 46 of the fuel cell 40b, even when the fuel cell 40b and the storage battery 50 are electrically connected through the electrical path 10 by turning on circuit breakers 80 and 80b. At this time, based on the switch control signal from the control device 60, the charging circuit 70e turns on switch 71a, allowing current to be supplied to the fuel cell 40a without being limited by resistor 76, without switching on and off switch 71b.

[0059] Based on a switch control signal from the control device 60, the charging circuit 70e turns on switches 73a, 72, and 74a and turns off switches 71a, 73b, and 74b, thereby charging the capacitors (output capacitor 41 and input capacitor 46) of the fuel cell 40a with the current flowing through the second current path 78. Based on the switch control signal from the control device 60, the charging circuit 70e charges the capacitor of the fuel cell 40a and then turns on switch 71a. This reduces the inrush current flowing through the output capacitor 41 and input capacitor 46 of the fuel cell 40a, even when the fuel cell 40a and the storage battery 50 are electrically connected through the electrical path 10 by turning on circuit breakers 80 and 80a. At this time, based on the switch control signal from the control device 60, the charging circuit 70e turns on switch 71b, thereby allowing current to be supplied to the fuel cell 40b without being limited by resistor 76, without switching on and off switch 71a.

[0060] The charging circuit 70f is similar to the charging circuit 70e.

[0061] <Control process for initial charging> Fig. 6 is a diagram showing an example of a control process related to initial charging. The control method shown in Fig. 6 is applicable to any of the charging circuits 70, 70a, 70b, 70c, 70d, 70e, and 70f shown in Figs.

[0062] In step S10, the control device 60 turns on the second switch 72 of the charging circuit while keeping the first switch 71 in the off state, so that the charging circuit charges the capacitor with the current flowing through the second current path 78.

[0063] In step S20, the control device 60 determines whether the capacitor is sufficiently charged. For example, as shown in Fig. 7, the control device 60 monitors whether the detected value of the capacitor voltage has risen to a predetermined voltage range, and determines that charging of the capacitor is complete when the detected value of the capacitor voltage has risen to the predetermined voltage range. Alternatively, as shown in Fig. 8, the control device 60 monitors whether a predetermined time TQ has elapsed since the second switch 72 was turned on, and determines that charging of the capacitor is complete when the predetermined time TQ has elapsed.

[0064] In step S30 of FIG. 6, when the control device 60 determines that charging of the capacitor is complete, it switches the first switch 71 from off to on.

[0065] In step S40, the control device 60 turns on the first switch 71, and then turns off the second switch 72. This cuts off the second current path 78, and the continuation of the current suppression by the resistor 76 is discontinued.

[0066] In step S50, the control device 60 starts the startup of the fuel cell 40 and the load 20. That is, the fuel cell 40 and the load 20 are started after the first switch 71 is turned on in step S30 or after the second switch 72 is turned off in step S40, so that the fuel cell 40 and the load 20 are started after all of the capacitors connected to the electric circuit 10 are charged. This makes it possible to prevent an inrush current generated by the startup of the fuel cell 40 or the load 20 from flowing to uncharged capacitors.

[0067] <Control process for independent startup> Inrush current may also occur when the inverter (load 20) starts up autonomously during a power grid abnormality such as a blackout. Therefore, it is also necessary to reduce the inrush current using a charging circuit during autonomous startup.

[0068] Before starting the control process (FIG. 6) related to initial charging, the control device 60 determines whether the conditions for independent startup of the fuel cell system are met. If the conditions for independent startup of the fuel cell system are met, the control device 60 starts the control process (FIG. 6) related to initial charging.

[0069] The independent startup condition for the fuel cell system is, for example, that the fuel cell system is stopped and that the AC power system to which the inverter (load 20) is connected via a transformer is experiencing a power outage. Alternatively, the independent startup condition for the fuel cell system may be that the fuel cell system is stopped and that the AC power system is experiencing a power outage and that a startup command for the fuel cell system is input. For example, the control device 60 can determine whether or not there is a power outage in the AC power system based on measurement results from measuring instruments installed in a distribution system connected to the AC power system and signals input via communication from a management device or the like that manages the AC power system.

[0070] In step S50 of FIG. 6, the control device 60 starts up one or more fuel cells 40 and one or more inverters (loads 20).

[0071] FIG. 9 is a diagram showing an example of the start-up process (step S50) of the fuel cell and the inverter.

[0072] When the process of step S50 in FIG. 6 starts, the control device 60 executes the processes of steps S306, S308, S310, and S312, and the processes of steps S314, S316, S318, and S320 in parallel.

[0073] In step S306, the control device 60 operates the auxiliary machinery 44 of the specific fuel cell 40 to start up the specific fuel cell 40. When the process of step S306 is completed, the control device 60 proceeds to step S308.

[0074] In step S308, the control device 60 controls the specific fuel cell 40 to start power generation in the fuel cell module 43 of the specific fuel cell 40. When the processing of step S308 is completed, the process proceeds to step S310.

[0075] In step S310, the control device 60 controls the auxiliary devices 44 of the remaining fuel cells 40, excluding the specific fuel cell 40, among the plurality of fuel cells 40, and starts up all the remaining fuel cell modules 43. After completing the processing of step S310, the control device 60 proceeds to step S312.

[0076] In step S312, the control device 60 controls the remaining fuel cells 40 to cause all the remaining fuel cell modules 43 to start power generation.

[0077] On the other hand, in step S314, the control device 60 starts up the inverter (load 20). If the fuel cell system includes a plurality of inverters, the control device 60 starts up all of the inverters.

[0078] When the process of step S314, i.e., the start-up of the inverter is completed, the control device 60 proceeds to step S316. If the fuel cell system includes multiple inverters, the control device 60 proceeds to step S316 when the start-up of all inverters is completed.

[0079] In step S316, the control device 60 starts outputting power from the inverter to the outside (i.e., the transformer side). If the fuel cell system includes multiple inverters, the control device 60 starts outputting power from all of the inverters to the outside (i.e., the transformer side).

[0080] This allows the control device 60 to supply power from the inverter to the power distribution system via the transformer. Upon completion of the process of step S316, the control device 60 proceeds to step S318.

[0081] In step S318, the control device 60 determines whether a predetermined waiting time TP has elapsed since the start of power supply to the outside of the inverter. If the waiting time TP has elapsed, the control device 60 proceeds to step S320, and if the waiting time TP has not elapsed, the control device 60 repeats the processing of step S318 until the waiting time TP has elapsed.

[0082] The process of step S318 may be performed before the process of step S314.

[0083] In step S320, the control device 60 starts the operation (operation) of the load devices connected to the power distribution system. If there are multiple load devices, the control device 60 starts the operation of all the load devices.

[0084] In addition, the control device 60 may start the operation of the load device by outputting a command directly to the load device, or may start the operation of the load device by outputting a command to another control device that can directly control the load device.

[0085] When the processes of both steps S312 and S320 are completed, the control device 60 ends the process of this flowchart.

[0086] Although the embodiments have been described above, they are presented as examples and the present invention is not limited to the above embodiments. The above embodiments can be implemented in various other forms, and various combinations, omissions, substitutions, modifications, etc. can be made without departing from the spirit of the invention. These embodiments and their modifications are included within the scope and spirit of the invention, and are also included in the scope of the invention and its equivalents as set forth in the claims. [Explanation of symbols]

[0087] 10 Electric circuit 12 DC Link 20,20c,20d load 21 Input capacitor 22 Inverter circuit 40,40a,40b fuel cell 41 Output capacitor 42,45 converter 43 Fuel Cell Module 44 Auxiliary Machinery 46 Input capacitor 50 Storage battery 60 Control device 70,70a,70b,70c,70d charging circuit 71 First Switch 72 Second Switch 76 Resistor 77 First current path 78 Second current path 80, 80a, 80b, 80c, 80d circuit breakers 101, 102, 103, 104, 105 Fuel cell system

Claims

1. a fuel cell including a first capacitor; A storage battery and an electrical path between the fuel cell and the storage battery; At least one charging circuit provided in the electrical path; the charging circuit includes a first current path provided with a first switch, a second current path provided with a resistor connected in parallel to the first switch, and a second switch provided in the second current path and connected in series to the resistor, wherein a current flows through the second current path when the second switch is turned on, and the first capacitor is charged with the current flowing through the second current path, and then the first switch is turned on; the second switch is turned off after the first switch is turned on, The fuel cell system is configured such that the fuel cell is started after the second switch is turned off.

2. a fuel cell including a first capacitor; A storage battery and an electrical path between the fuel cell and the storage battery; At least one charging circuit provided in the electrical path; the charging circuit includes a first current path provided with a first switch and a second current path provided with a resistor connected in parallel to the first switch, and charges the first capacitor with a current flowing through the second current path, and then turns on the first switch; The fuel cell system, wherein the fuel cell is started after the first switch is turned on.

3. a fuel cell including a first capacitor; A storage battery and an electrical path between the fuel cell and the storage battery; At least one charging circuit provided in the electrical path; the charging circuit includes a first current path provided with a first switch and a second current path provided with a resistor connected in parallel to the first switch, and charges the first capacitor with a current flowing through the second current path, and then turns on the first switch; The fuel cell is a plurality of fuel cells, the electrical path includes a DC link to which the first capacitors of the plurality of fuel cells are connected; The charging circuit is provided between the DC link and the storage battery.

4. a fuel cell including a first capacitor; A storage battery and an electrical path between the fuel cell and the storage battery; At least one charging circuit provided in the electrical path; the charging circuit includes a first current path provided with a first switch and a second current path provided with a resistor connected in parallel to the first switch, and charges the first capacitor with a current flowing through the second current path, and then turns on the first switch; The fuel cell is a plurality of fuel cells, The charging circuit includes a plurality of charging circuits that individually charge the first capacitors of the plurality of fuel cells.

5. a fuel cell including a first capacitor; A storage battery and an electrical path between the fuel cell and the storage battery; At least one charging circuit provided in the electrical path; the charging circuit includes a first current path provided with a first switch and a second current path provided with a resistor connected in parallel to the first switch, and charges the first capacitor with a current flowing through the second current path, and then turns on the first switch; The fuel cell is a plurality of fuel cells, The charging circuit includes a common charging circuit that individually charges the first capacitors of the plurality of fuel cells.

6. a fuel cell including a first capacitor; A storage battery and an electrical path between the fuel cell and the storage battery; At least one charging circuit provided in the electrical path; a load connected to the electrical path and including a second capacitor; a first current path provided with a first switch and a second current path provided with a resistor connected in parallel to the first switch, and the charging circuit charges the first capacitor and the second capacitor with a current flowing through the second current path, and then turns on the first switch.

7. 7. The fuel cell system according to claim 6, wherein the load is started after the first switch is turned on.

8. 7. The fuel cell system according to claim 6, wherein the load includes a power conversion device including the second capacitor.

9. 9. The fuel cell system according to claim 8, wherein the power conversion device is a reverse conversion device that starts a self-sustaining operation by reverse converting the power obtained from the electric circuit and supplying the power to an external device after the first switch is turned on.

10. a fuel cell including a first capacitor; A storage battery and an electrical path between the fuel cell and the storage battery; At least one charging circuit provided in the electrical path; a first current path provided with a first switch and a second current path provided with a resistor connected in parallel to the first switch, and the charging circuit charges the first capacitor with current flowing from the storage battery to the second current path, and then turns on the first switch.

11. 11. The fuel cell system according to claim 10, wherein the charging circuit includes a second switch connected in series with the resistor, and when the second switch is turned on, a current flows through the second current path.

12. a load connected to the electrical path and including a second capacitor; 12. The fuel cell system according to claim 10, wherein the charging circuit charges the second capacitor with the current flowing from the storage battery through the second current path, and then turns on the first switch.

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