Fuel cell system

Abstract

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

Description

[[Technical Field]]

[0001] The present disclosure relates to a fuel cell system. [[Background Art]]

[0002] Conventionally, in a power generation system using a fuel cell as a power generator, a technology for suppressing an inrush current flowing through a capacitor provided at an input part of a power conditioner is known (see, for example, Patent Document 1). [[Prior Art Literature]] [[Patent Literature]]

[0003] [[Patent Document 1]] Japanese Unexamined Patent Application Publication No. 2013-078183 [[Summary of the Invention]] [[Problem to be Solved by the Invention]]

[0004] A fuel cell may include a capacitor. In this case, when the fuel cell is connected to an electric path, an inrush current may flow from the electric path to the capacitor.

[0005] The present disclosure provides a fuel cell system capable of reducing an inrush current flowing through a capacitor included in a 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; an electric path between said fuel cell and said storage battery; at least one charging circuit provided on said electric path; The charging circuit includes a first current path through which a first switch is provided, and a second current path through which a resistor connected in parallel with the first switch is provided. The fuel cell system is provided in which the first capacitor is charged with the current flowing through the second current path, and then the first switch is turned on. [Effects of the Invention]

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

[0008] [Figure 1] This figure shows an example configuration of a fuel cell system according to the first embodiment. [Figure 2] This figure shows an example configuration of a fuel cell system according to the second embodiment. [Figure 3] This figure shows an example configuration of a fuel cell system according to the third embodiment. [Figure 4] This figure shows an example configuration of a fuel cell system according to the fourth embodiment. [Figure 5] This figure shows an example configuration of a fuel cell system according to the fifth embodiment. [Figure 6] This flowchart shows an example of control processing related to initial charging. [Figure 7] This figure shows an example of how to determine if the initial charge is complete. [Figure 8] This figure shows an example of how to determine if the initial charge is complete. [Figure 9] This figure shows an example of the startup process (step S50) for the fuel cell and the inverter. [Modes for carrying out the invention]

[0009] Several embodiments will be described below with reference to the drawings.

[0010] <An example configuration of a fuel cell system according to the first embodiment> Figure 1 is a diagram showing an example configuration of a fuel cell system according to the first embodiment. The fuel cell system 101 shown in Figure 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 a fuel cell 40, a storage battery 50, a load 20, an electrical circuit 10, circuit breakers 80a, 80b, 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 also be a unit including a fuel cell module 43 and auxiliary equipment 44. The auxiliary equipment 44 is powered by electricity supplied from the electrical circuit 10.

[0012] The fuel cell module 43 generates electricity by receiving fuel. The fuel cell module 43 includes a fuel cell stack that 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 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 other types of fuel cells such as a phosphate 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 the 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 steps up the voltage output from the fuel cell stack. The converter 42 outputs DC power having a voltage higher than the voltage output from the fuel cell stack to the outside of the fuel cell module 43. The 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 an output section 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 device 44 is equipment for operating the fuel cell module 43, and assists the power generation operation of the fuel cell module 43. The auxiliary device 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 is operated by power supplied from the electric 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 in an open state, fuel such as hydrogen is supplied to the fuel cell module 43, and when the fuel valve is in a closed state, 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 an 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 is operated by power supplied from the electric circuit 10 or a power supply system (not shown). The opening and closing of the purge valve is controlled by the control device 60. When the purge valve is in an open state, the inert gas such as nitrogen is supplied to the fuel pipe of the fuel system, and when the purge valve is in a closed state, the supply of the inert gas such as nitrogen to the fuel pipe is stopped.

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

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

[0021] Load 20 is a device that operates by receiving power from circuit 10 and is electrically connected to circuit 10. Examples of load 20 include load devices that consume DC power from circuit 10 (such as resistive loads), DC / DC converters that convert DC from circuit 10 to DC and output it, and inverse converters (DC / AC converters) that convert DC from circuit 10 to AC.

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

[0023] The inverter, for example, connects to the power lines of the power system when the power system is functioning normally, and exchanges power between the power system and the circuit 10. In the event of an abnormality such as a power outage in the power system, the inverter is disconnected from the power lines of the power system by a system switch. While disconnected from the power lines by the system switch, the inverter performs independent operation, for example, by converting the power obtained from the fuel cell 40 or storage battery 50 via the circuit 10 and supplying it to a load device (not shown), or it stops its own operation. A specific example of a system switch is a circuit breaker.

[0024] The inverter device converts the DC current of the circuit 10 into AC current of a predetermined voltage and frequency and outputs it. For example, the inverter device is a power conditioner (PCS) that includes an inverter circuit 22 that converts DC current into three-phase AC current of a predetermined voltage and frequency.

[0025] The load 20 includes an input capacitor 21 that is electrically connected to the circuit 10. The input capacitor 21 is, for example, a capacitive element provided at the input of an inverter circuit 22 that smooths 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 battery 50 is a secondary battery electrically connected to the circuit 10. The battery 50 can discharge power to the outside of the fuel cell system 101 via the inverter (load 20) and can charge (store) power supplied from the fuel cell 40 via the circuit 10. The battery 50 is, for example, a capacitor such as a lithium-ion capacitor (LIC). The battery 50 may be a lithium-ion battery with a liquid electrolyte, or an all-solid-state battery with a solid electrolyte. The battery 50 is electrically connected to the load 20 and the fuel cell 40 via the circuit 10.

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

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

[0029] The circuit breakers 80, 80a, and 80c each interrupt the circuit 10 automatically or manually. The circuit breakers 80, 80a, and 80c may also interrupt the circuit 10 in accordance with an interruption signal from the control device 60. Specific examples of circuit breakers 80 include circuit breakers that protect the circuit 10 from abnormal currents by interrupting the circuit 10 upon detection of abnormal currents flowing through the circuit 10.

[0030] Circuit breaker 80 is a device that disconnects the battery 50 from the circuit 10, interrupting the circuit 10 between the DC link 12 and the battery 50. Circuit breaker 80a is a device that disconnects the fuel cell 40 from the circuit 10, interrupting the circuit 10 between the DC link 12 and the fuel cell 40. Circuit breaker 80c is a device that disconnects the load 20 from the circuit 10, interrupting the 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 CPU (Central Processing Unit), FPGA (Field Programmable Gate Array), or ASIC (Application Specific Integrated Circuit). The control device 60 may also be a computer having 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 memory, or by designing a circuit for a special application.

[0033] The control device 60 may have a function to detect whether the power system is normal or abnormal based on the detection result of the voltage of the power system externally connected to the inverter via a system switch, etc., when the load 20 is an inverter. The control device 60 may also detect whether or not there is an abnormality in the power system by other known detection methods. For example, if the control device 60 detects that the power system is abnormal, such as a power outage, while the system switch is ON, it switches the system switch from ON to OFF. For example, if the control device 60 detects that the power system is normal (for example, the power system has recovered from an abnormality such as a power outage) while the system switch is OFF, it switches the system switch from OFF to ON.

[0034] The control device 60 operates the inverter (load 20) in a grid-connected operation mode, for example, when the grid switch is ON (i.e., the power grid is functioning normally), in which power is exchanged between the power grid and the circuit 10. The control device 60 operates the inverter (load 20) in a standalone operation mode, for example, when the grid switch is OFF (i.e., the power grid is experiencing an abnormality such as a power outage), in which power obtained from the fuel cell 40 or battery 50 via the circuit 10 is converted in reverse and supplied to an external load device. The control device 60 may also stop the operation of the inverter (load 20) when the grid switch is OFF (i.e., the power grid 1 is experiencing an abnormality such as a power outage). In this case, the control device 60 may also stop the fuel cell 40. The control device 60 may also stop the auxiliary system and the fuel cell 40 simultaneously or sequentially.

[0035] The control device 60 may perform a process to start the stopped fuel cell system 101 (start-up process), or it may perform a process to stop the operating fuel cell system 101 (stop-down process). Starting the fuel cell system 101 means starting the auxiliary equipment system of the fuel cell system 101 while the fuel cell system 101 is stopped, and starting the fuel cell 40 while the auxiliary equipment system is running. Stopping the fuel cell system 101 means stopping the operation of the auxiliary equipment system and the fuel cell 40 simultaneously or sequentially.

[0036] The charging circuit 70 is a charging circuit provided in the electrical circuit 10, and is a circuit that prevents inrush current flowing through the electrical 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 located on the DC side of the fuel cell 40 or the smoothing input capacitor 46 located on the DC side of the auxiliary equipment 44 is not charged. At this time, when the circuit breaker 80 and circuit breaker 80a are turned on, and the fuel cell 40 and the storage battery 50 are connected via the circuit 10, a very large current (inrush current) flows through the circuit 10 to the output capacitor 41 or the input capacitor 46. This inrush current may lead to equipment failure in the fuel cell system 101 or false detection of anomalies due to a voltage drop in the circuit 10.

[0038] Similarly, immediately after the load 20 is started, the smoothing input capacitor 21 located on the DC side of the load 20 is not charged. At this time, when the circuit breakers 80 and 80c are turned on, and the load 20 and the battery 50 are connected via the circuit 10, a very large current (inrush current) flows through the circuit 10 to the input capacitor 21. This inrush current may lead to equipment failure in the fuel cell system 101 or false detection of an anomaly due to a voltage drop in the circuit 10.

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

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

[0041] Based on the 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. As a result, due to the inrush current suppression effect of the resistor 76 placed in the second current path 78, a relatively small current flows from the storage battery 50 to the fuel cell 40 via the circuit 10, and the output capacitor 41 and the input capacitor 46 are charged (precharged) relatively slowly. 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 when the circuit breaker 80 and circuit breaker 80a are turned on, and the fuel cell 40 and the storage battery 50 are connected to allow current to flow through the circuit 10, the inrush current flowing through the output capacitor 41 and the input capacitor 46 is reduced.

[0042] Similarly, the charging circuit 70 charges the input capacitor 21 with the current flowing through the second current path 78 based on the switch control signal from the control device 60, and then turns on the first switch 71. As a result, due to the inrush current suppression effect of the resistor 76 placed in the second current path 78, a relatively small current flows from the storage battery 50 to the load 20 via the circuit 10, and the input capacitor 21 is charged (precharged) relatively slowly. 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 when the circuit breaker 80 and circuit breaker 80c are turned on, and the load 20 and the storage battery 50 are connected to allow current to flow through the circuit 10, 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 false detection of abnormalities due to voltage drops in the circuit 10 is reduced.

[0044] The control device 60 turns off the second switch 72, which is located in the second current path 78, after the first switch 71 is turned on. As a result, the second current path 78 is interrupted, and the current suppression by the resistor 76 is eliminated.

[0045] The first switch 71 and the second switch 72 open and close their contacts according to the switch control signals from the control device 60. Examples of the first switch 71 and the second switch 72 include electromagnetic contactors and relays. The resistor 76 may be any resistor that consumes power, such as a thermistor or other resistor that can be used for other purposes.

[0046] <An example configuration of a fuel cell system according to the second embodiment> Figure 2 shows an example configuration of a fuel cell system according to the second embodiment. In the second embodiment, the description of the configuration, operation, and effects similar to those of the first embodiment will be omitted by referring to the above description. The fuel cell system 102 shown in Figure 2 differs from the fuel cell system 101 according to the first embodiment in that it has multiple fuel cells 40 and multiple loads 20.

[0047] In Figure 2, the fuel cell system 102 comprises a plurality of fuel cells 40 (in this example, two fuel cells 40a and 40b) electrically connected to the circuit 10, and loads 20 (in this example, two loads 20c and 20d) electrically connected to the 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 as each other. The plurality of loads 20 may have the same configuration as each other.

[0048] The fuel cell system 102 according to the second embodiment has circuit breakers 80b and 80d added to the fuel cell system 101. Circuit breaker 80b is a device that disconnects the fuel cell 40b from the circuit 10, interrupting the circuit 10 between the DC link 12 and the fuel cell 40b. Circuit breaker 80d is a device that disconnects the load 20d from the circuit 10, interrupting the circuit 10 between the DC link 12 and the load 20d.

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

[0050] The charging circuit 70 charges the output capacitor 41 and the input capacitor 46 with the current flowing through the second current path 78 based on the switch control signal from the control device 60, and then turns on the first switch 71. Therefore, even when circuit breakers 80 and 80b are turned on, allowing current to flow between the fuel cell 40b and the storage battery 50 through the circuit 10, the inrush current flowing through the output capacitor 41 and the input capacitor 46 of the fuel cell 40b is reduced. Similarly, even when circuit breakers 80 and 80d are turned on, allowing current to flow between the load 20d and the storage battery 50 through the circuit 10, the inrush current flowing through the input capacitor 21 of the load 20d is reduced.

[0051] <An example configuration of a fuel cell system according to the third embodiment> Figure 3 shows an example configuration of a fuel cell system according to the third embodiment. In the third embodiment, the description of the configuration, operation, and effects similar to those of the embodiments described above will be omitted by referring to the above description. The fuel cell system 103 shown in Figure 3 differs from the fuel cell system 102 according to the second embodiment in that the charging circuit 70 includes a plurality of charging circuits that individually charge each capacitor of the fuel cells 40a and 40b. The fuel cell system 103 shown in Figure 3 differs from the fuel cell system 102 according to the second embodiment in that the charging circuit 70 includes a plurality of charging circuits that individually charge each capacitor of the loads 20c and 20d.

[0052] In Figure 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, the capacitors of multiple fuel cells can be charged individually. Charging circuits 70a and 70b may be the same as charging circuit 70.

[0053] In Figure 3, the charging circuit 70c is provided between the load 20c and the DC link 12. The charging circuit 70d is provided between the load 20d and the DC link 12. By providing a charging circuit for each load, the capacitors of multiple loads can be charged individually. Charging circuits 70c and 70d can be the same as charging circuit 70.

[0054] <An example configuration of a fuel cell system according to the fourth embodiment> Figure 4 shows an example configuration of a fuel cell system according to the fourth embodiment. In the fourth embodiment, the description of the configuration, operation, and effects, which are the same as those of the embodiments described above, will be omitted by referring to the above description. The fuel cell system 104 shown in Figure 4 differs from the fuel cell system 103 according to the third embodiment in that there is no charging circuit 70 provided between the DC link 12 and the storage battery 50.

[0055] In Figure 4, even without the charging circuit 70, the capacitors of multiple fuel cells can be charged individually by providing a charging circuit for each fuel cell. Similarly, the capacitors of multiple loads can be charged individually by providing a charging circuit for each load.

[0056] <An example configuration of a fuel cell system according to the fifth embodiment> Figure 5 shows an example configuration of a fuel cell system according to the fifth embodiment. In the fifth embodiment, a description of the configuration, operation, and effects similar to those of the embodiments described above will be omitted by referring to the above description. The fuel cell system 105 shown in Figure 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 and 40b. The fuel cell system 105 shown in Figure 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 and 20d.

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

[0058] The charging circuit 70e charges the capacitors (output capacitor 41 and input capacitor 46) of the fuel cell 40b with the current flowing through the second current path 78 by turning on switches 73b, 72, and 74b and turning off switches 71b, 73a, and 74a based on the switch control signal from the control device 60. The charging circuit 70e charges the capacitors of the fuel cell 40b based on the switch control signal from the control device 60, and then turns on switch 71b. As a result, even when the circuit breakers 80 and 80b are turned on, and the fuel cell 40b and the storage battery 50 are connected in a way that allows current to flow through the circuit 10, the inrush current flowing through the output capacitor 41 and input capacitor 46 of the fuel cell 40b is reduced. At this time, the charging circuit 70e can supply current to the fuel cell 40a without the restriction of the resistor 76 by turning on switch 71a based on the switch control signal from the control device 60, without switching switch 71b on and off.

[0059] The charging circuit 70e charges the capacitors (output capacitor 41 and input capacitor 46) of the fuel cell 40a with the current flowing through the second current path 78 by turning on switches 73a, 72, and 74a and turning off switches 71a, 73b, and 74b based on the switch control signal from the control device 60. The charging circuit 70e charges the capacitors of the fuel cell 40a based on the switch control signal from the control device 60, and then turns on switch 71a. As a result, even when the circuit breaker 80 and circuit breaker 80a are turned on, and the fuel cell 40a and the storage battery 50 are connected in a way that allows current to flow through the circuit 10, the inrush current flowing through the output capacitor 41 and input capacitor 46 of the fuel cell 40a is reduced. At this time, the charging circuit 70e can supply the fuel cell 40b with current unrestricted by the resistor 76 without switching switch 71a on and off by turning on switch 71b based on the switch control signal from the control device 60.

[0060] The charging circuit 70f is the same as the charging circuit 70e.

[0061] <Control processing related to initial charging> Figure 6 shows an example of control processing related to initial charging. The control method shown in Figure 6 is applicable to any of the charging circuits 70, 70a, 70b, 70c, 70d, 70e, and 70f shown in Figures 1 to 5.

[0062] In step S10, the control device 60 turns on the second switch 72 while keeping the first switch 71 of the charging circuit in the OFF state. As a result, 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 has been sufficiently charged. For example, as shown in Figure 7, the control device 60 monitors whether the detected voltage of the capacitor has risen to a predetermined voltage range, and if the detected voltage of the capacitor has risen to a predetermined voltage range, it determines that the capacitor has been fully charged. Alternatively, as shown in Figure 8, the control device 60 monitors whether a predetermined time TQ has elapsed since the second switch 72 was turned on, and if the predetermined time TQ has elapsed, it determines that the capacitor has been fully charged.

[0064] In step S30 of Figure 6, if the control device 60 determines that the capacitor has finished charging, it switches the first switch 71 from off to on.

[0065] In step S40, after the first switch 71 is turned on, the control device 60 switches the second switch 72 from on to off. As a result, the second current path 78 is interrupted, and the current suppression by the resistor 76 is eliminated.

[0066] In step S50, the control device 60 starts 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 they are started after all the capacitors connected to the circuit 10 have been charged. This prevents the inrush current generated by starting the fuel cell 40 or the load 20 from flowing into uncharged capacitors.

[0067] <Control processing related to autonomous startup> In the event of a power system abnormality such as a blackout, an inrush current may occur when the inverter (load 20) starts up independently. Therefore, it is necessary to reduce the inrush current by using a charging circuit, even during independent startup.

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

[0069] The conditions for the self-starting of the fuel cell system are, for example, that the fuel cell system is stopped and the AC power system to which the inverter (load 20) is connected via a transformer is experiencing a power outage. Alternatively, the conditions for the self-starting of the fuel cell system may be that the fuel cell system is stopped, the AC power system is experiencing a power outage, and a start 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 from the measurement results of measuring instruments installed in the distribution system connected to the AC power system, or from signals input via communication from a management device that manages the AC power system.

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

[0071] Figure 9 shows an example of the startup process (step S50) for the fuel cell and the inverter.

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

[0073] In step S306, the control device 60 activates the auxiliary equipment 44 of a specific fuel cell 40 to start the specific fuel cell 40. Once the process in step S306 is complete, the control device 60 proceeds to step S308.

[0074] In step S308, the control device 60 controls a specific fuel cell 40 and starts generating power from the fuel cell module 43 of that specific fuel cell 40. Once the processing in step S308 is complete, the process proceeds to step S310.

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

[0076] In step S312, the control device 60 controls the remaining fuel cells 40 and starts generating power from all remaining fuel cell modules 43.

[0077] Meanwhile, in step S314, the control device 60 activates the inverter (load 20). If the fuel cell system includes multiple inverters, the control device 60 activates all of them.

[0078] Once the processing in step S314, i.e., the startup of the inverter, is complete, the control device 60 proceeds to step S316. If the fuel cell system includes multiple inverters, once the startup of all inverters is complete, the control device 60 proceeds to step S316.

[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 each of the inverters to the outside (i.e., the transformer side).

[0080] As a result, the control device 60 can supply power to the power distribution system from the inverter via the transformer. Once the processing in step S316 is completed, 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, starting from 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. If the waiting time TP has not elapsed, the process in step S318 is repeated until the waiting time TP has elapsed.

[0082] Furthermore, the processing in step S318 may be moved before the processing in step S314.

[0083] In step S320, the control device 60 starts the operation (activation) 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 of them.

[0084] Furthermore, the control device 60 may start the operation of the load device by directly outputting a command to the load device, or it may start the operation of the load device by outputting a command to another control device capable of directly controlling the load device.

[0085] Once both steps S312 and S320 are completed, the control device 60 terminates the processing shown in this flowchart.

[0086] As described above, embodiments have been explained, but these embodiments are presented as examples only, and the present invention is not limited by these embodiments. The above embodiments can be implemented in various other forms, and various combinations, omissions, substitutions, and modifications are possible without departing from the spirit of the invention. These embodiments and their variations are included in the scope and spirit of the invention, as well as in the claims of the invention and its equivalents. [Explanation of Symbols]

[0087] 10 Electric circuit 12 DC Link 20,20c,20d load 21 Input Capacitors 22 Inverter Circuit 40,40a,40b fuel cell 41 Output Capacitor 42,45 converter 43 Fuel cell module 44 Auxiliary equipment 46 Input Capacitors 50 Storage batteries 60 Control device 70,70a,70b,70c,70d charging circuit 71. Switch 1 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 systems

Claims

1. A fuel cell including a first capacitor, Storage batteries and The circuit between the fuel cell and the battery, The circuit comprises at least one charging circuit, The charging circuit includes a first current path through which a first switch is provided, and a second current path through which a resistor connected in parallel to the first switch is provided, and the first capacitor is charged with the current flowing through the second current path before the first switch is turned on, in a fuel cell system.

2. The fuel cell system according to claim 1, wherein the charging circuit includes a second switch connected in series with the resistor, and when the second switch is turned on, current flows through the second current path.

3. The fuel cell system according to claim 2, wherein the second switch is provided in the second current path and is turned off after the first switch is turned on.

4. The fuel cell system according to claim 3, wherein the fuel cell is started after the second switch is turned off.

5. The fuel cell system according to claim 1, wherein the fuel cell is started after the first switch is turned on.

6. There are multiple fuel cells, The circuit includes a DC link to which the first capacitors of the plurality of fuel cells are connected. The fuel cell system according to claim 1, wherein the charging circuit is provided between the DC link and the storage battery.

7. There are multiple fuel cells, The fuel cell system according to claim 1, wherein the charging circuit includes a plurality of charging circuits for individually charging the first capacitors of a plurality of fuel cells.

8. There are multiple fuel cells, The fuel cell system according to claim 1, wherein the charging circuit includes a common charging circuit for individually charging the first capacitors of a plurality of fuel cells.

9. The aforementioned circuit is connected and further comprises a load including a second capacitor, The fuel cell system according to any one of claims 1 to 8, wherein the charging circuit charges the second capacitor with the current flowing through the second current path, and then turns on the first switch.

10. The fuel cell system according to claim 9, wherein the load is activated after the first switch is turned on.

11. The fuel cell system according to claim 9, wherein the load includes a power converter including the second capacitor.

12. The fuel cell system according to claim 11, wherein the power conversion device is a reverse converter that, after the first switch is turned on, reverse-converts the power obtained from the circuit and starts independent operation to supply it to the outside.

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