Power control method and power control system

Abstract

To provide a power control method that uses a system power supply, a fuel battery, and a storage battery as a power source, and can set a reduced capacity of the storage battery.SOLUTION: A power control method includes a storage battery 22 that can charge power from a system power supply 11 and a fuel battery stack 71, and a fuel battery auxiliary machinery that drives the fuel battery stack 71 with the power from the system power supply 11 and the storage battery 22, and when power outage occurs in the system power supply 11, executes stop control of the fuel battery stack 71, and supplies the power generated by the fuel battery stack 71 to the fuel battery auxiliary machinery during the execution of the stop control. The power control method detects a current temperature of the fuel battery stack 71, estimates a power consumption amount of the fuel battery auxiliary machinery and a power generation amount by the fuel battery stack 71 from the start to the completion of the stop control when the stop control is started during the detection of the current temperature, and sets a target stored power remaining amount of the storage battery 22 on the basis of a difference obtained by subtracting the power generation amount from the power consumption amount.SELECTED DRAWING: Figure 4

Description

Technical Field

[0001] The present invention relates to a power control method and a power control system.

Background Art

[0002] Patent Document 1 discloses a power control system using a utility power source, a fuel cell, and a storage battery as power sources, and always stores in the storage battery the power necessary for stop control in order to reliably execute stop control of the fuel cell when the utility power source is interrupted.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, as in Patent Document 1, if the storage battery is always made to store the power necessary for stop control, a corresponding storage capacity is required, and the size and cost of the storage battery increase.

[0005] An object of the present invention is to provide a power control method that uses a utility power source, a fuel cell, and a storage battery as power sources and can set a small capacity for the storage battery.

Means for Solving the Problems

[0006] The power control method according to the present invention includes a storage battery that can be charged with power from a utility power source and / or a fuel cell, and a fuel cell auxiliary machine that drives a fuel cell with power from the utility power source and / or the storage battery. When the utility power source fails, it is a power control method that executes stop control of the fuel cell and supplies the power generated by the fuel cell to the fuel cell auxiliary machine during the execution of the stop control. In this power control method, the current temperature of the fuel cell is detected, and when the stop control is started at the time of detecting the current temperature, the power consumption of the fuel cell auxiliary machine from the start to the completion of the stop control is estimated. When the stop control is started at the time of detecting the current temperature, the power generation amount of the fuel cell that can generate power during the execution of the stop control is estimated, and the target remaining charge amount of the storage battery is set based on the difference obtained by subtracting the power generation amount from the power consumption amount.

Advantages of the Invention

[0007] According to the present invention, when the stop control of the fuel cell is started when the current temperature of the fuel cell is detected, the capacity of the storage battery can be set to be smaller by the amount of the power generation amount of the fuel cell that can generate power during the execution of the stop control, and it is possible to reduce the size and cost of the storage battery. In addition, since the allowable charge capacity obtained by subtracting the target remaining charge amount from the upper limit value of the remaining charge amount can be set large, the degree of freedom of charging and discharging of the storage battery can be improved. Furthermore, economic operation such as charging with night power can be performed within the range of the allowable charge capacity, and the electricity cost can also be reduced.

Brief Description of the Drawings

[0008]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

MODE FOR CARRYING OUT THE INVENTION

[0009] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

[0010] [Configuration of Power Control System] FIG. 1 is a schematic diagram of the power control system of the present embodiment. The power control system of the present embodiment supplies power to the load 31, the specific load 41, and the fuel cell auxiliary machine using the utility power supply 11, the fuel cell system 7, and the storage battery 22 as power sources.

[0011] The power control system of the present embodiment includes a first line 1 connecting the utility power supply 11, the switch S3, the DC / AC converter 12, the DC / DC converter 13, the switch S1, and the fuel cell stack 71 in series in this order, and a second line 2 branching from a position between the DC / AC converter 12 and the DC / DC converter 13 of the first line 1 and connecting the DC / DC converter 21, the switch S2, and the storage battery 22 in series in this order.

[0012] In addition, the power control system of this embodiment includes a third line 3 that branches from a position between the switch S3 on the first line 1 and the DC / AC converter 12 and is connected in the order of the switch S4 and the load 31, and a fourth line 4 that branches from a position between the connection position of the third line 3 and the first line 1 and the switch S4 and is connected in the order of the switch S5 and the specific load 41.

[0013] Furthermore, the power control system of this embodiment includes a fifth line 5 that branches from between the switch S4 on the fourth line 4 and the specific load 41 and is connected in the order of the switch S6 and the fuel cell system 7 (AC / DC converter 74), and a sixth line 6 that branches from a position between the utility power supply 11 on the first line 1 and the switch S3 and is connected to a position between the switch S4 on the fourth line 4 and the specific load 41 via an uninterruptible power supply device 61 described later. And the power control system includes a power control controller 8 that controls the entire system.

[0014] The utility power supply 11 is a single-phase three-wire or three-phase three-wire AC power supply (commercial power supply). The utility power supply 11 is connected to the DC / AC converter 12 via the switch S1, connected to the load 31 via the switch S1 and the switch S4, and connected to the specific load 41 via the switch S1 and the switch S5.

[0015] The load 31 is, for example, a TV connected to a general-purpose outlet, home appliances such as an air conditioner, or an electric vehicle, and receives power supply from the utility power supply 11, the fuel cell system 7 (fuel cell stack 71), and the storage battery 22.

[0016] Power is supplied to the specific load 41 from the utility power supply 11 while the utility power supply 11 is operating, but when the utility power supply 11 experiences a power outage, it receives power supply from the fuel cell system 7, the storage battery 22, and the uninterruptible power supply device 61. The specific load 41 is for driving the power control system and can include the power control controller 8, the fuel cell control controller 76, the DC / AC converter 12, the DC / DC converter 13, the DC / DC converter 21, etc. described later.

[0017] The DC / AC converter 12 is a bidirectional voltage converter whose operating state can be mutually switched between a first state in which it adjusts the output voltage (AC voltage) of the utility power supply 11 (converts it to a DC voltage) and supplies it to the storage battery 22, and a second state in which it adjusts the output voltage of the storage battery 22 and / or the output voltage (DC voltage) of the fuel cell system 7 (fuel cell stack 71) (converts it to an AC voltage) and supplies it to the load 31, the specific load 41, and the fuel cell auxiliaries (pump 72, blower 73, AC / DC converter 74, DC / DC converter 75, fuel cell controller 76).

[0018] The storage battery 22 is a secondary battery such as a lithium-ion battery (all-solid-state battery) or a lead-acid battery, and can be charged by receiving power supply from the utility power supply 11 or the fuel cell system 7, and can also discharge to supply power to the load 31, the specific load 41, and the fuel cell auxiliaries.

[0019] The storage battery 22 is connected to the DC / AC converter 12 via the DC / DC converter 21. The DC / DC converter 21 is a bidirectional voltage converter whose operating state can be mutually switched between a first state in which it boosts the output voltage of the storage battery 22 and supplies it to the DC / AC converter 12, and a second state in which it steps down the output voltage of the DC / AC converter 12 (DC voltage) and / or the output voltage of the DC / DC converter 13 and supplies it to the storage battery 22. A switch S2 is interposed between the storage battery 22 and the DC / DC converter 21.

[0020] The fuel cell system 7 includes a fuel cell stack 71 and fuel cell auxiliaries (pump 72, blower 73, AC / DC converter 74, DC / DC converter 75, fuel cell controller 76).

[0021] The fuel cell stack 71 is a solid oxide fuel cell (SOFC: Solid Oxide Fuel Cell), which includes an electrolyte layer formed of a solid oxide such as ceramic, and is obtained by stacking battery cells sandwiched between an anode (fuel electrode) to which fuel is supplied and a cathode (air electrode) to which air containing oxygen is supplied. Further, a catalyst for reforming fuel is disposed in the battery cell, and power is generated by an electrochemical reaction between the reformed fuel (anode gas) and oxygen (cathode gas).

[0022] The output voltage of the fuel cell stack 71 is output to the DC / DC converter 13 via the switch S1. The DC / DC converter 13 boosts the output voltage of the fuel cell stack 71 and outputs it to the DC / AC converter 12 and the DC / DC converter 21. Therefore, the DC / DC converter 13 (fuel cell stack 71) and the DC / DC converter 21 (storage battery 22) are connected in parallel to the DC / AC converter 12.

[0023] Note that the fuel cell stack 71 continues to generate power except when the power control system is operating and it stops due to the stop control described later. Also, although not shown, a temperature sensor for detecting the current temperature of the fuel cell stack 71 is disposed in the fuel cell stack 71.

[0024] The pump 72 supplies the fuel stored in a fuel tank (not shown) to the fuel cell stack 71 (anode).

[0025] The blower 73 supplies air (oxygen) to the fuel cell stack 71 (cathode).

[0026] Although not shown, the fuel cell system 7 has a combustor that mixes the anode off-gas discharged from the fuel cell stack 71 (anode) and the cathode off-gas discharged from the fuel cell stack 71 (cathode off-gas) for fuel. The combustor heats the fuel cell stack 71 during warm-up and normal power generation of the fuel cell stack 71.

[0027] The AC / DC converter 74 is turned on and off by the fuel cell control controller 76, and converts the AC voltage input from the utility power supply 11, the DC / AC converter 12 (fuel cell stack 71, storage battery 22), and the uninterruptible power supply device 61 described later into a DC voltage and outputs it to the DC / DC converter 75.

[0028] The DC / DC converter 75 adjusts the output voltage of the AC / DC converter 74 and outputs it to the pump 72 and the blower 73. The output to the pump 72 and the output to the blower 73 are individually controlled by the fuel cell control controller 76. Note that the AC / DC converter 74 and the DC / DC converter 75 may be integrated.

[0029] When a command signal for normal power generation is input from the power control controller 8 to the fuel cell control controller 76, the AC / DC converter 74 is operated, and the outputs for the pump 72 and the blower 73 of the DC / DC converter 75 are set to the outputs for normal power generation, respectively.

[0030] When a command signal for starting stop control is input from the power control controller 8 to the fuel cell control controller 76, the outputs for the pump 72 and the blower 73 of the DC / DC converter 75 are set to the outputs for stop control (outputs lower than the outputs for normal power generation), respectively. Thereby, the fuel cell stack 71 continues to generate power while its temperature decreases.

[0031] When a command signal for stopping power generation is input to the fuel cell control controller 76 after starting stop control from the power control controller 8, the output for the blower 73 of the DC / DC converter 75 is maintained (or returned to the output for normal power generation), and the output of the pump 72 is set to zero.

[0032] When a command signal for completing stop control is input from the power control controller 8 to the fuel cell control controller 76, the output for the blower 73 of the DC / DC converter 75 is set to zero, and the operation of the AC / DC converter 74 is stopped.

[0033] The uninterruptible power supply device 61 stores a predetermined amount of power from the utility power supply 11 and supplies power to the load 31, the specific load 41, and the fuel cell auxiliary equipment when a power outage of the utility power supply 11 is detected, and operates constantly while the power control system is in operation.

[0034] FIG. 2 is a schematic diagram of the uninterruptible power supply device 61. The uninterruptible power supply device 61 includes an AC / DC converter 611, a backup battery 612, and a DC / AC converter 613.

[0035] The AC / DC converter 611 converts the output voltage (AC voltage) of the utility power supply 11 into a DC voltage and supplies it to the backup battery 612.

[0036] The DC / AC converter 613 converts the output voltage (DC voltage) of the backup battery 612 into an AC voltage and supplies power to the load 31, the specific load 41, and the fuel cell auxiliary equipment. Note that the AC / DC converter 611 and the DC / AC converter 613 operate using the backup battery 612 as a power source.

[0037] As the backup battery 612, a secondary battery similar to the battery 22 can be applied, but its capacity is set to cover the power required by the load 31, the specific load 41, and the fuel cell auxiliary equipment (and further the AC / DC converter 611 and the DC / AC converter 613) for the time (e.g., 5 seconds) from the detection of the power outage of the utility power supply 11 until the power of the battery 22 is supplied to the specific load 41 and the fuel cell system 7 (AC / DC converter 74).

[0038] For example, assume that before the detection of a power outage of the utility power supply 11, the power of the utility power supply 11 and the power of the fuel cell stack 71 via the DC / AC converter 12 are supplied to the load 31, the specific load 41, and the fuel cell auxiliary machine, the DC / DC converter 21 is stopped, and the switch S2 is set to the off state. In this case, when the utility power supply 11 experiences a power outage, only the fuel cell stack 71 can supply power, resulting in a power shortage for the load 31, the specific load 41, and the fuel cell auxiliary machine, and there is a risk that the system will stop immediately.

[0039] Similarly, assume that before the detection of a power outage of the utility power supply 11, the power of the utility power supply 11 is supplied to the load 31, the specific load 41, and the fuel cell auxiliary machine, and the power of the fuel cell stack 71 is supplied to the storage battery 22 via the DC / DC converter 21. In this case, when the utility power supply 11 experiences a power outage, the power supply to the load 31, the specific load 41, and the fuel cell auxiliary machine (pump 72, blower 73) stops, and the system stops immediately.

[0040] However, in any case, by arranging the uninterruptible power supply device 61, it is possible to avoid a power shortage for the load 31, the specific load 41, and the fuel cell auxiliary machine, and avoid the stop of the system.

[0041] A current sensor (not shown) is arranged in the AC / DC converter 611. The current sensor (not shown) monitors the input and output currents of the AC / DC converter 74, and when there is a change (when it becomes zero) in the input and output currents, it determines that the utility power supply 11 has experienced a power outage and outputs a detection signal to the power control controller 8.

[0042] As shown in FIG. 1, the power control controller 8 controls the DC / AC converter 12, the DC / DC converter 13, the DC / DC converter 21, and the switches S1 - S6. Further, a detection signal is input to the power control controller 8 from a current sensor (not shown) disposed in the uninterruptible power supply device 61, information on the remaining battery level (charge rate (SOC)) is input from a remaining battery level sensor (not shown) disposed in the storage battery 22, and information on the current temperature of the fuel cell stack 71 is input from a temperature sensor (not shown) disposed in the fuel cell stack 71. The power control controller 8 is composed of a microcomputer or the like, and a program for executing the power control method of the present embodiment is installed therein.

[0043] When the system starts up, the power control controller 8 starts warming the fuel cell stack 71. At this time, the power control controller 8 transmits a command signal for warming to the fuel cell control controller 76, and turns on the switches S3, S5, and S6 to supply the power of the utility power supply 11 to the fuel cell auxiliary equipment.

[0044] Upon receiving the command signal, the fuel cell control controller 76 starts the AC / DC converter 74 and the DC / DC converter 75 to operate the pump 72 and the blower 73 with the output for warming, and starts the ignition device (not shown) attached to the combustor (not shown). Then, the fuel (before reforming) and air (oxygen) supplied to the combustor (not shown) via the fuel cell stack 71 are burned by the ignition device (not shown), thereby heating the combustor (not shown), and the fuel cell stack 71 is warmed by the heat of the combustor (not shown).

[0045] When the temperature of the combustor (not shown) reaches a temperature at which the fuel can be burned through the combustion catalyst, the ignition device (not shown) stops.

[0046] When the temperature of the fuel cell stack 71 reaches a temperature at which the fuel can be reformed, the power control controller 8 transmits a command signal for normal power generation to the fuel cell control controller 76, turns on the switch S1, and starts the DC / DC converter 13.

[0047] When a command signal for normal power generation is input, the fuel cell controller 76 controls the output of the DC / DC converter 75 so that the outputs of the pump 72 and the blower 73 operate with the outputs for normal power generation.

[0048] During power generation of the fuel cell system 7 (when the generated power is equal to or greater than the minimum power that the DC / DC converter 13 can extract), the power control controller 8 sets the switch S1 to the on state, and when power generation stops (when the generated power becomes lower than the minimum power that the DC / DC converter 13 can extract), the switch S1 is set to the off state (non-conductive state).

[0049] During operation of the fuel cell system 7 (including the state where power generation has stopped), the power control controller 8 sets the switch S6 to the on state, and when the fuel cell system 7 stops, the switch S6 is set to the off state.

[0050] When the utility power source 11 is operating, for example, during nighttime when the electricity rate of the utility power source 11 is low, the power control controller 8 preferentially sets the switches S3, S4, and S5 to the on state, and during that time, supplies power from the utility power source 11 to the load 31, the specific load 41, and the fuel cell auxiliary equipment. Further, the power control controller 8 sets the DC / AC converter 12 to the first state and sets the DC / DC converter 21 to the first state, thereby charging the storage battery 22 with the power from the utility power source 11.

[0051] In order to reduce the use of the utility power source 51, for example, during daytime when the electricity rate of the utility power source 11 is high, the power control controller 8 preferentially sets the switch S3 to the off state and the DC / AC converter 12 to the second state, and sets the time for setting the DC / DC converter 21 to the second state to be long, and during that time, supplies the output voltages of the storage battery 22 and the fuel cell system 7 (fuel cell stack 71) to the load 31, the specific load 41, and the fuel cell auxiliary equipment.

[0052] The power control controller 8 can preset the remaining charge amount of the storage battery 22 based on the predicted information of the power demand of the load 31 (for example, the power demand of the next day).

[0053] The power control controller 8 controls the remaining charge amount while referring to the information of the remaining charge amount of the storage battery 22 so that the remaining charge amount does not reach a predetermined lower limit value and does not exceed a predetermined upper limit value. For example, when the remaining charge amount approaches the lower limit value, the DC / DC converter 21 is switched from the second state to the first state, and the storage battery 22 is charged by the power supply of the fuel cell system 7 (fuel cell stack 71). Or, when the operating state of the DC / AC converter 12 is the second state, it is switched to the first state to charge the storage battery 22 by the power supply from the utility power supply 11. Also, when the remaining charge amount reaches the upper limit value, the switch S1 is maintained in the on state and the switch S2 is set to off, or the switch S1 is set to the off state and the operating state of the DC / DC converter 21 is switched from the first state to the second state to supply power to the load 31, the specific load 41, and the fuel cell auxiliary equipment.

[0054] Here, the upper limit value of the remaining charge amount is set so that the sum of the remaining charge amount of the storage battery 22 when the current temperature (fuel cell temperature) of the fuel cell stack 71 is detected and the generated electric power amount of the fuel cell stack 71 that can generate power during the execution of the stop control when the stop control is started at the time of detecting the current temperature does not exceed the preset maximum remaining charge amount. Here, the maximum remaining charge amount is set as the maximum value of the remaining charge amount, for example, to reduce the deterioration of the storage battery 22. At this time, for example, the temperature of the fuel cell stack 71 is set to the maximum temperature (constant value) at which the fuel cell stack 71 can generate power without deterioration, and the generated electric power amount is set to the maximum value (constant value), so that the upper limit value may be set to be constant.

[0055] Further, the lower limit value (target remaining charge amount) of the remaining charge amount is set as the difference between the current temperature of the fuel cell stack 71 (fuel cell temperature) detected and the power consumption required by the fuel cell auxiliary equipment (particularly the pump 72 and the blower 73) from the start to the completion of the stop control when the stop control is started at the time of detecting the current temperature, and the power generation amount of the fuel cell stack 71 that can be generated during the execution of the stop control (the power generation amount that can be extracted by the DC / DC converter 13).

[0056] When the current temperature of the fuel cell stack 71 decreases and there is a risk of insufficient power generation during normal power generation of the fuel cell stack 71, the power control controller 8 can also increase the temperature of the fuel cell stack 71 by increasing the extraction current of the DC / DC converter 13. At this time, by decreasing the output current of the DC / AC converter 12 (in the case of the second state), it is also possible to keep the power supply to the storage battery 22 constant.

[0057] When a detection signal is input from a current sensor (not shown), that is, when a power failure of the utility power supply 11 is detected, the power control controller 8 executes stop control of the fuel cell system 7.

[0058] Note that the switch S1 and the switch S2 may be set to be always on, or the switch S1 may be omitted and the fuel cell stack 71 may be directly connected to the DC / DC converter 13, and the switch S2 may be omitted and the storage battery 22 may be directly connected to the DC / DC converter 21.

[0059] [Control before and after Stop Control of Power Control System] FIG. 3 shows the control before and after detecting a power failure of the utility power supply 11 in the power control system of the present embodiment in chronological order. Before the power failure of the utility power supply 11 occurs, the storage battery 22 is arbitrarily set within a range where the remaining charge amount of the storage battery 22 is higher than the lower limit value and equal to or less than the upper limit value under the control of the power control controller 8, and within this range, the storage battery 22 performs charge and discharge. Before the power failure of the utility power supply 11 occurs, the fuel cell system 7 continuously executes normal power generation.

[0060] After detecting a power failure of the system power supply 11, the storage battery 22 discharges to supply power to the specific load 41 and the fuel cell auxiliary equipment. In addition, the fuel cell system 7 executes stop control while consuming the generated power of the fuel cell stack 71 at the start of the stop control. After that, when the power generation of the fuel cell stack 71 stops, the fuel cell system 7 continues the stop control only with the power of the storage battery 22. Further, the fuel cell system 7 completes the stop control when the temperature of the fuel cell stack 71 reaches a predetermined temperature (for example, the upper limit of the temperature at which deterioration due to oxygen in the battery cells can be reduced).

[0061] [Control before stop control of the power control system] FIG. 4 is a control flow before stop control of the fuel cell system 7 of the power control system according to the present embodiment. FIG. 5 is a diagram showing the relationship between the temperature of the fuel cell stack 71 and the generated power of the fuel cell stack 71. FIG. 6 is a diagram showing the relationship between the temperature of the fuel cell stack 71 and the power consumption of the fuel cell auxiliary equipment (particularly the pump 72 and the blower 73).

[0062] In the present embodiment, the current temperature (fuel cell temperature) of the fuel cell stack 71 is detected at a predetermined frequency before the fuel cell system 7 stops, and the remaining charge amount (target remaining charge amount) of the storage battery 22 is calculated in order to complete the stop control in a complete state even when the stop control is started at the current temperature.

[0063] As shown in FIG. 4, in step S101, the power control controller 8 detects the current temperature of the fuel cell stack 71 by a temperature sensor (not shown).

[0064] In step S102, the power control controller 8 estimates the amount of generated power that the fuel cell stack 71 can generate during the execution of the stop control when the stop control of the fuel cell system 7 is started at the time of detection of the current temperature.

[0065] As shown in FIG. 5, the power generation power (P1) of the fuel cell stack 71 decreases as the temperature drops, and becomes zero when the lower limit temperature (Tmin) is reached. Note that the power generation power (P1) is the maximum power that can be extracted in the IV characteristics depending on the temperature of the fuel cell stack 71.

[0066] Also, the temperature (T(t)) of the fuel cell stack 71 can be expressed by the following formula (1), where Tp is the current temperature at time (t = 0) of the fuel cell stack 71, T0 is the outside air temperature, and k is the time constant of the temperature drop of the fuel cell stack 71.

Equation

[0067] Further, the time (t1) when the temperature of the fuel cell stack 71 reaches the lower limit temperature (Tmin) at which power generation is possible can be expressed by the following formula (2).

Equation

[0068] Therefore, the power generation energy amount (W1) can be expressed by the following formula (3) using the power generation power P1(T(t)) of the fuel cell stack 71.

Equation

[0069] In step S103, when the stop control of the fuel cell system 7 is started at the time of detecting the current temperature, the power consumption amount of the fuel cell auxiliary machines (pump 72, blower 73) from the start of the stop control to the end is estimated.

[0070] As shown in FIG. 6, the power consumption (P2) of the fuel cell auxiliary machines (particularly the pump 72 and the blower 73) is set to decrease as the temperature drops, but it may be constant regardless of the temperature change. Also, after detecting the temperature of the fuel cell stack 71, when the temperature of the fuel cell stack 71 reaches a predetermined temperature (T L(The time (t2) until it reaches a temperature lower than the lower limit value (Tmin)) can be expressed by the following formula (4).

Equation

[0071] Therefore, the power consumption amount (W2) can be expressed by the following formula (5) using the power consumption P2(T(t)) of the fuel cell auxiliary equipment (especially the pump 72 and the blower 73).

Equation

[0072] In step S104, the target remaining charge amount is calculated based on the difference obtained by subtracting the power generation amount (W1) from the power consumption amount (W2).

[0073] [Target remaining charge amount] Figure 7 is a diagram showing the relationship among the temperature of the fuel cell stack 71, the power generation power of the fuel cell stack 71, and the target remaining charge amount. For simplicity of explanation, as shown in the upper part of Figure 7, it is assumed that the temperature of the fuel cell stack 71 linearly decreases with the passage of time after the start time (t = 0) of the stop control, reaches the lower limit temperature (Tmin) at time t1, and reaches a predetermined temperature (T L ) at time t2.

[0074] As shown in the middle part of Figure 7, the power generation power of the fuel cell stack 71 monotonically decreases after the start time (t = 0), and becomes zero when the temperature of the fuel cell stack 71 reaches the lower limit temperature (Tmin) at time t1. However, here, it shows the case where power generation is stopped because the power generation power of the fuel cell stack 71 becomes lower than the minimum power that can be extracted by the DC / DC converter 13 (Figure 1) when the temperature of the fuel cell stack 71 reaches the set temperature (T1) higher than the lower limit temperature (Tmin) at a time t1' earlier than time t1. In this case, the power generation power that can be extracted from the fuel cell stack 71 during the stop control can be represented by the region (A).

[0075] The power consumption of the fuel cell auxiliary machines (especially the pump 72 and the blower 73) monotonically decreases with the passage of time after the start time (t = 0) as shown in the lower part of FIG. 7. However, the power consumption amount of the fuel cell auxiliary machines is calculated by integrating the power consumption from the start time (t = 0) to the time (t2). Among these, the area (A) is the part that can be covered by the power generation amount of the fuel cell stack 71 among the power consumption amount of the fuel cell auxiliary machines, and the area (B) is the part that is covered by the output of the storage battery 22 among the power consumption amount of the fuel cell auxiliary machines, and this becomes the target remaining storage amount.

[0076] Therefore, according to the present embodiment, the storage battery 22 does not cover all of the power consumption amount of the fuel cell auxiliary machines (especially the pump 72 and the blower 73), and a part of it can be covered by the fuel cell stack 71 during the stop control.

[0077] [Adjustment of the remaining storage amount of the storage battery 22] FIG. 8 is a control flow for adjusting the remaining storage amount of the storage battery 22.

[0078] In step S801, the power control controller 8 determines whether the storage battery 22 can be charged from the utility power supply 11 or the fuel cell system 7. If YES, it proceeds to step S802, and if NO, it stays in step S801. Whether it can be charged from the fuel cell system 7 is determined by whether the switch S1 is set to the ON state and whether the DC / DC converter 13 is operating. Whether it can be charged from the utility power supply 11 is determined by whether the DC / AC converter 12 is operating in the first state and whether it has not received a detection signal.

[0079] In step S802, the power control controller 8 acquires information on the remaining storage amount from a remaining storage amount sensor (not shown).

[0080] In step S803, the power control controller 8 determines whether the value obtained by subtracting the target remaining storage amount calculated in step S104 (FIG. 4) and a predetermined margin from the remaining storage amount is zero or more. If YES, it proceeds to RETURN, and if NO, it proceeds to step S804.

[0081] Here, the margin is set (for example, 2 [%] of the upper limit value of the remaining battery charge) in consideration of the charge-discharge characteristics of the storage battery 22 (particularly the charging response to the input current) and the detection error of the remaining battery charge.

[0082] In step S804, the power control controller 8 increases the remaining battery charge by the absolute value of the value obtained by subtracting the target remaining battery charge and the margin from the remaining battery charge. In this case, the power control controller 8 switches the operating state of the DC / DC converter 21 from the first state to the second state, and switches from the second state to the first state when the remaining battery charge has increased by the amount of the absolute value, or turns off the switch S2.

[0083] [Stop control of the fuel cell system 7 in the power control system] FIG. 9 is a control flow of the stop control of the fuel cell system 7 in the power control system of the present embodiment.

[0084] In step S901, the power control controller 8 detects a power outage of the utility power supply 11 when a detection signal is input.

[0085] In step S902, the fuel cell system 7 determines whether it is in normal power generation. If YES, it proceeds to END. If NO, it proceeds to step S903.

[0086] In step S903, the power control controller 8 starts the stop control of the fuel cell system 7. At this time, the power control controller 8 transmits a command signal for starting the stop control to the fuel cell control controller 76.

[0087] In step S904, the power control controller 8 sets the switches S3 and S4 to the off state. Thereby, the utility power supply 11 and the load 31 are disconnected from the fuel cell system 7. At this time, the specific load 41 and the fuel cell auxiliary equipment can receive power supply from the uninterruptible power supply device 61.

[0088] In step S905, the power control controller 8 activates the DC / DC converter 21, sets its operating state to the second state, and sets the switch S2 to the on state. Also, if the operating state of the DC / AC converter 12 is the first state, it is set to the second state. Note that if the DC / DC converter 21 has already been activated and set to the first state and the switch S2 is in the on state, the power control controller 8 switches the operating state of the DC / DC converter 21 to the second state. Thereby, the power of the fuel cell stack 71 and the storage battery 22 is supplied to the specific load 41 and the fuel cell auxiliary equipment.

[0089] Here, the output current of the DC / DC converter 13 is set to the current value when the power taken out in the IV characteristics of the fuel cell stack 71 reaches the maximum power that can be taken out, and the output current of the DC / DC converter 21 is set to the current value when outputting the power obtained by subtracting the supply power of the DC / DC converter 13 from the total power consumption of the specific load 41 and the fuel cell auxiliary equipment (especially the pump 72 and the blower 73). Note that the capacity of the backup storage battery 612 of the uninterruptible power supply device 61 is small, and the remaining power storage is depleted and the power supply stops within a short time (for example, 5 seconds) after shifting from step S904 to step S905.

[0090] In step S906, the power control controller 8 determines whether the temperature of the fuel cell stack 71 has reached the set temperature (T1) (or the lower limit temperature (Tmin)). If YES, it proceeds to step S907, and if NO, it remains in step S906.

[0091] In step S907, the power control controller 8 stops the DC / DC converter 13 and sets the switch S1 to the off state. Also, the power control controller 8 stops the operation of the pump 72 (the output of the DC / DC converter 75 to the pump 72) by sending a command signal for power generation stop to the fuel cell controller 76. Thereby, the power generation of the fuel cell stack 71 stops, but the operation of the blower 73 continues, and the fuel cell stack 71 is continuously cooled by the air supplied by the blower 73.

[0092] In step S908, the power control controller 8 determines whether the temperature of the fuel cell stack 71 has reached a predetermined temperature (T L ). If YES, the process proceeds to step S909. If NO, the process remains in step S908.

[0093] In step S909, the power control controller 8 transmits a command signal for completing the stop control to the fuel cell control controller 76. At this time, the fuel cell control controller 76 stops the operation of the blower 73 by stopping the DC / DC converter 75, and further stops the operation of the AC / DC converter 74. Also, the power control controller 8 stops the operation of the DC / DC converter 21, and sets the switches S2 and S6 to the off state, so that the entire system enters the standby state.

[0094] Thereafter, when the utility power supply 11 is restored, the standby state of the power control system is released, the switches S3 - S6 are set to the on state again, the operation of the uninterruptible power supply device 61 is restarted, and the power supply to the load 31 is restarted based on a request from the outside.

[0095] [Effects of the present embodiment] According to the power control method of the present embodiment, a storage battery 22 that can be charged with power from the utility power supply 11 and / or the fuel cell (fuel cell stack 71), and a fuel cell auxiliary machine (pump 72, blower 73) that drives the fuel cell (fuel cell stack 71) with power from the utility power supply 11 and / or the storage battery 22 are included. When the utility power supply 11 experiences a power outage, stop control of the fuel cell (fuel cell stack 71) is executed, and during the execution of the stop control, the power generated by the fuel cell (fuel cell stack 71) is supplied to the fuel cell auxiliary machine (pump 72, blower 73). This is a power control method in which the current temperature of the fuel cell (fuel cell stack 71) is detected, and when stop control is started at the time of detecting the current temperature, the power consumption amount (W2) of the fuel cell auxiliary machine (pump 72, blower 73) from the start to the completion of the stop control is estimated. When stop control is started at the time of detecting the current temperature, the power generation amount (W1) of the fuel cell (fuel cell stack 71) that can generate power during the execution of the stop control is estimated, and the target remaining charge amount of the storage battery 22 is set based on the difference obtained by subtracting the power generation amount (W1) from the power consumption amount (W2).

[0096] By the above method, when stop control of the fuel cell (fuel cell stack 71) is started when the current temperature of the fuel cell (fuel cell stack 71) is detected, the capacity of the storage battery 22 can be set to be smaller by the amount of the power generation amount of the fuel cell (fuel cell stack 71) that can generate power during the execution of the stop control, and it becomes possible to reduce the size and cost of the storage battery 22. Also, since the allowable charge capacity obtained by subtracting the target remaining charge amount from the upper limit value of the remaining charge amount can be set large, the degree of freedom of charge and discharge of the storage battery 22 can be improved. Furthermore, economic operation such as charging with nighttime power can be performed within the range of the allowable charge capacity, and the electricity cost can also be reduced.

[0097] In the present embodiment, the power generation amount (W1) is calculated based on the power generation temperature characteristic (Fig. 5) representing the relationship between the power generation power and temperature of the fuel cell (fuel cell), and the temperature decrease characteristic (Equation (1)) representing the temperature change until the temperature of the fuel cell (fuel cell stack 71) reaches the power generation lower limit temperature (Tmin or set temperature (T1)).

[0098] By the above method, the generated power amount (W1) can be calculated in a simple manner, and depletion of the remaining charge amount of the storage battery 22 during stop control can be avoided, so that deterioration of the fuel cell (fuel cell stack 71) can be suppressed.

[0099] In the present embodiment, the cycle of detecting the current temperature is set based on the estimated temperature decrease rate of the fuel cell (fuel cell stack 71) at the start of stop control when stop control is started at the time of detecting the current temperature.

[0100] In the above method, the estimated decrease rate is obtained by differentiating Equation (1) with respect to time. Therefore, when a solid oxide fuel cell is applied as the fuel cell stack 71 by the above method, since its temperature gradient is gentle, the cycle of detecting the current temperature, that is, the control cycle, can be lengthened, and accordingly, the calculation load on the power control controller 8 (microcomputer) can be reduced.

[0101] In the present embodiment, when it is determined that the storage battery 22 can be charged from the utility power supply 11 and / or the fuel cell (fuel cell stack 71), the storage battery 22 is charged so that the remaining charge amount (charge efficiency) of the storage battery 22 becomes equal to or greater than the target remaining charge amount.

[0102] By the above method, since the target remaining charge amount is secured in the storage battery 22, the fuel cell system 7 can be surely stopped even when the utility power supply 11 fails.

[0103] In the present embodiment, when the remaining charge amount of the storage battery 22 is equal to or greater than the target remaining charge amount, charge and discharge of the storage battery 22 are executed based on a request from the outside (load 31) within a range from the target remaining charge amount to a predetermined upper limit value higher than the target remaining charge amount.

[0104] By the above method, for example, economic operation can be achieved by refraining from using the utility power supply 11 during the daytime, and the electricity cost of the utility power supply 11 (commercial power supply) can be reduced.

[0105] In the present embodiment, the upper limit value is set such that the sum of the remaining charge amount of the storage battery 22 at the time of detecting the current temperature and the generated power amount (W1) of the fuel cell (fuel cell stack 71) that can generate power during the execution of the stop control when the stop control is started at the time of detecting the current temperature does not exceed the maximum remaining charge amount set for the storage battery 22.

[0106] By the above method, the charging range of the storage battery 22 can be defined, and charging control by the power control controller 8 becomes possible.

[0107] In the present embodiment, further included are a voltage converter (DC / AC converter 12) that connects the utility power supply 11 and the storage battery 22, a load 31 connected in parallel to one side of the voltage converter (DC / AC converter 12) together with the utility power supply 11, a first switch (switch S3) that disconnects and connects between the utility power supply 11 and the voltage converter (DC / AC converter 12), and a second switch (switch S4) that disconnects and connects between the load 31 and the voltage converter (DC / AC converter 12). The fuel cell (fuel cell stack 71) is connected to the other side different from one side of the voltage converter (DC / AC converter 12) together with the storage battery 22, the fuel cell auxiliary machines (pump 72, blower 73) are connected to one side of the voltage converter (DC / AC converter 12) together with the utility power supply 11 and the load 31, and the operating state of the voltage converter (DC / AC converter 12) can be mutually switched between a first state of adjusting the output voltage of the utility power supply 11 (converting the AC voltage to the DC voltage) and supplying it to the storage battery 22, and a second state of adjusting the output voltage of the storage battery 22 and / or the output voltage of the fuel cell (fuel cell stack 71) (converting it to the AC voltage) and supplying it to the load 31 and / or the fuel cell auxiliary machines (pump 72, blower 73). When the utility power supply 11 is operating, the operating state of the voltage converter (DC / AC converter 12) is set to the first state, and when the utility power supply 11 has a power outage, the first switch (switch S3) and the second switch (switch S4) are set to the non-conducting state, and the operating state of the voltage converter (DC / AC converter 12) is switched from the first state to the second state.

[0108] When the stop control of the fuel cell (fuel cell stack 71) is started when the current temperature of the fuel cell (fuel cell stack 71) is detected by the above method, and the target remaining charge of the storage battery 22 can be set lower by the amount of the generated power that the fuel cell (fuel cell stack 71) can generate during the execution of the stop control. Therefore, the charge and discharge range of the storage battery 22 can be expanded accordingly.

[0109] The power control system of the present embodiment includes a storage battery 22 connected to the utility power supply 11 and the fuel cell (fuel cell stack 71), a fuel cell auxiliary machine (pump 72, blower 73) that receives power supply from the utility power supply 11 and / or the storage battery 22 and drives the fuel cell (fuel cell stack 71), and a controller (power control controller 8) that controls the remaining charge of the storage battery 22. The controller (power control controller 8) executes the stop control of the fuel cell (fuel cell stack 71) when the utility power supply 11 fails, and supplies the power generated by the fuel cell (fuel cell stack 71) during the execution of the stop control to the fuel cell auxiliary machine (pump 72, blower 73). The power control system further includes a temperature detection means (temperature sensor (not shown)) for detecting the current temperature of the fuel cell (fuel cell stack 71). The controller (fuel cell stack 71) estimates the power consumption (W2) of the fuel cell auxiliary machine (pump 72, blower 73) from the start to the completion of the stop control when the stop control is started at the time of detecting the current temperature, estimates the generated power amount (W1) of the fuel cell (fuel cell stack 71) that can generate power during the execution of the stop control when the stop control is started at the time of detecting the current temperature, and sets the target remaining charge of the storage battery 22 based on the difference obtained by subtracting the generated power amount (W1) from the power consumption (W2).

[0110] With the above configuration, when the stop control of the fuel cell (fuel cell stack 71) is started when the current temperature of the fuel cell (fuel cell stack 71) is detected, the capacity of the storage battery 22 can be set to be reduced by the amount of the generated power that the fuel cell (fuel cell stack 71) can generate during the execution of the stop control, and the size and cost of the storage battery 22 can be reduced. In addition, since the allowable charge capacity obtained by subtracting the target remaining charge amount from the upper limit value of the remaining charge amount can be set large, the degree of freedom of charging and discharging of the storage battery 22 can be improved. Furthermore, economic operation such as charging with night-time power can be performed within the range of the allowable charge capacity, and the electricity cost can also be reduced.

[0111] In this embodiment, a first voltage converter (DC / AC converter 12) that electrically connects the utility power supply 11 and the storage battery 22, a load 31 connected in parallel to one side of the first voltage converter (DC / AC converter 12) together with the utility power supply 11, a first switch (switch S3) that disconnects and connects between the utility power supply 11 and the first voltage converter (DC / AC converter 12), a second switch (switch S4) that disconnects and connects between the load 31 and the first voltage converter (DC / AC converter 12), and a detection means (current sensor (not shown)) that detects a power outage of the utility power supply 11 are further included. A fuel cell (fuel cell stack 71) is connected to the other side different from the one side of the first voltage converter together with the storage battery 22. A fuel cell auxiliary machine (pump 72, blower 73) is connected to one side of the first voltage converter (DC / AC converter 12) together with the utility power supply 11 and the load 31. The operating state of the first voltage converter (DC / AC converter 12) can be mutually switched between a first state of adjusting the output voltage (AC voltage) of the utility power supply 11 (converting it into a DC voltage) and supplying it to the storage battery 22, and a second state of adjusting the output voltage of the storage battery 22 and / or the output voltage (DC voltage) of the fuel cell (fuel cell stack 71) (converting it into an AC voltage) and supplying it to the load 31 and / or the fuel cell auxiliary machine (pump 72, blower 73). The controller (power control controller 8) sets the operating state of the first voltage converter (DC / AC converter 12) to the first state while the utility power supply 11 is operating, sets the first switch (switch S3) and the second switch to a non-conducting state when the detection means (current sensor (not shown)) detects a power outage of the utility power supply 11, and switches the operating state of the first voltage converter (DC / AC converter 12) from the first state to the second state.

[0112] With the above configuration, the target remaining charge amount of the storage battery 22 can be lowered by the amount of the generated power of the fuel cell stack 71 during stop control. Therefore, the charge and discharge range of the storage battery 22 can be expanded by that amount.

[0113] In this embodiment, the system further includes a specific load 41 for driving the system and an uninterruptible power supply device 61 that temporarily stores the power supplied from the utility power supply 11 and supplies it to the load 31, the specific load 41, and the fuel cell auxiliary equipment (pump 72, blower 73).

[0114] With the above configuration, even if the utility power supply 11 suddenly loses power, the uninterruptible power supply device 61 can supply power to the load 31, the specific load 41, and the fuel cell auxiliary equipment (pump 72, blower 73). Therefore, the control of the fuel cell system 7 that controls the fuel cell (fuel cell stack 71) can be continued without control failure.

[0115] In this embodiment, the uninterruptible power supply device 61 includes a backup storage battery 612, a second voltage converter (AC / DC converter 611) that adjusts (converts to a DC voltage) the voltage (AC voltage) of the utility power supply 11 and supplies it to the backup storage battery 612, and a third voltage converter (DC / AC converter 613) that adjusts (converts to an AC voltage) the output voltage (DC voltage) of the backup storage battery 612 and supplies it to the load 31, the specific load 41, and the fuel cell auxiliary equipment. The second voltage converter (AC / DC converter 611) and the third voltage converter (DC / AC converter 613) are constantly driven during system operation.

[0116] With the above configuration, the uninterruptible power supply device 61 can be constructed with a simple configuration.

[0117] In the present embodiment, a fourth voltage converter (DC / DC converter 21) is further included that boosts the output voltage of the storage battery 22 and outputs it to the first voltage converter (DC / AC converter 12). When the fourth voltage converter (DC / DC converter 21) is stopped before the detection means (current sensor (not shown)) detects a power failure of the utility power supply 11, the controller (power control controller 8) starts the fourth voltage converter (DC / DC converter 21) when the detection means (current sensor (not shown)) detects a power failure of the utility power supply 11. The capacity of the backup storage battery 612 is set corresponding to the power required by the load 31, the specific load 41, and the fuel cell auxiliary equipment (pump 72, blower 73) from the detection of the stop of the utility power supply 11 until the fourth voltage converter (DC / DC converter 21) is started.

[0118] With the above configuration, the size and cost of the backup storage battery 612 can be reduced.

[0119] In the present embodiment, the detection means (current sensor (not shown)) is a current sensor (not shown) arranged in the second voltage converter (AC / DC converter 611). The current sensor (not shown) detects the stop of the utility power supply 11 based on the change in the input / output current of the second voltage converter (AC / DC converter 611) and transmits a detection signal to the controller (power control controller 8).

[0120] With the above configuration, it is possible to detect a power failure of the utility power supply 11 in a short time without having a dedicated line interruption detection function.

[0121] As described above, the embodiments of the present invention have been described. However, the above embodiments merely show a part of the application examples of the present invention, and are not intended to limit the technical scope of the present invention to the specific configurations of the above embodiments. Also, the above embodiments can be combined as appropriate.

Explanation of Reference Numerals

[0122] 11 Utility power supply, 22 Storage battery, 71 Fuel cell stack, 72 Pump, 73 Blower, 8 Power control controller

Claims

1. A system power source and / or a storage battery that can be charged with power from a fuel cell, and a fuel cell auxiliary machine that drives the fuel cell with the power from the system power source and / or the storage battery, and includes: A power control method that executes stop control of the fuel cell when the system power source fails and supplies the power generated by the fuel cell during the execution of the stop control to the fuel cell auxiliary machine, comprising: Detecting the current temperature of the fuel cell; When starting the stop control at the time of detecting the current temperature, estimating the power consumption of the fuel cell auxiliary machine from the start to the completion of the stop control; When starting the stop control at the time of detecting the current temperature, estimating the power generation amount of the fuel cell that can generate power during the execution of the stop control; A power control method for setting a target remaining charge amount of the storage battery based on a difference obtained by subtracting the power generation amount from the power consumption amount.

2. The power control method according to claim 1, wherein the power generation amount is calculated based on a power generation temperature characteristic representing the relationship between the power generation power and temperature of the fuel cell and a temperature decrease characteristic representing the temperature change until the temperature of the fuel cell reaches a lower limit temperature for power generation.

3. The power control method according to claim 1, wherein the detection period of the current temperature is set based on an estimated temperature decrease rate of the fuel cell at the start of the stop control when starting the stop control at the time of detecting the current temperature.

4. The power control method according to claim 1, wherein when it is determined that the storage battery can be charged from the system power source and / or the fuel cell, the storage battery is charged so that the remaining charge amount of the storage battery is equal to or greater than the target remaining charge amount.

5. The power control method according to claim 4, wherein when the remaining charge amount of the storage battery is equal to or greater than the target remaining charge amount, charge and discharge of the storage battery are performed based on an external request within a range from the target remaining charge amount to a predetermined upper limit value higher than the target remaining charge amount.

6. The power control method according to claim 5, wherein the upper limit value is set so that the sum of the remaining charge amount of the storage battery at the time of detecting the current temperature and the power generation amount of the fuel cell that can generate power during the execution of the stop control when starting the stop control at the time of detecting the current temperature does not exceed the maximum remaining charge amount set for the storage battery.

7. A voltage converter that connects the system power source and the storage battery, A load connected in parallel with one of the voltage converters together with the system power supply, A first switch for disconnecting and connecting between the system power supply and the voltage converter, A second switch for disconnecting and connecting between the load and the voltage converter, further comprising, The fuel cell is connected to the other side different from the one side of the voltage converter together with the storage battery, The fuel cell auxiliary machine is connected to the one side of the voltage converter together with the system power supply and the load, The operating state of the voltage converter can be mutually switched between a first state of adjusting the output voltage of the system power supply and supplying it to the storage battery, and a second state of adjusting the output voltage of the storage battery and / or the output voltage of the fuel cell and supplying it to the load and / or the fuel cell auxiliary machine, The operating state of the voltage converter is set to the first state while the system power supply is operating, The power control method according to claim 1, wherein when the system power supply stops power supply, the first switch and the second switch are set to a non-conducting state, and the operating state of the voltage converter is switched from the first state to the second state.

8. A storage battery connected to a system power supply and a fuel cell, A fuel cell auxiliary machine that receives power supply from the system power supply and / or the storage battery and drives the fuel cell, A controller for controlling the remaining charge amount of the storage battery, comprising, The controller is a power control system that executes stop control of the fuel cell when the system power supply stops power supply and supplies the power generated by the fuel cell during the execution of the stop control to the fuel cell auxiliary machine, Further comprising temperature detection means for detecting the current temperature of the fuel cell, The controller, When starting the stop control at the time of detecting the current temperature, estimates the power consumption amount of the fuel cell auxiliary machine from the start of the stop control to the completion, When starting the stop control at the time of detecting the current temperature, estimates the power generation amount of the fuel cell that can generate power during the execution of the stop control, A power control system that sets the target remaining charge amount of the storage battery based on the difference obtained by subtracting the power generation amount from the power consumption amount.

9. A first voltage converter for electrically connecting the system power supply and the storage battery, A load connected in parallel with one of the first voltage converters together with the system power supply, A first switch for disconnecting and connecting between the system power supply and the first voltage converter, A second switch for disconnecting and connecting between the load and the first voltage converter, Further comprising detection means for detecting a power failure of the system power supply, The fuel cell is connected to the other side of the first voltage converter, which is different from the one side, together with the storage battery, The fuel cell auxiliary machine is connected to the one side of the first voltage converter together with the system power supply and the load, The operating state of the first voltage converter can be mutually switched between a first state of adjusting the output voltage of the system power supply and supplying it to the storage battery, and a second state of adjusting the output voltage of the storage battery and / or the output voltage of the fuel cell and supplying it to the load and / or the fuel cell auxiliary machine, The controller, Sets the operating state of the first voltage converter to the first state while the system power supply is operating, When the detection means detects a power failure of the system power supply, sets the first switch and the second switch to a non-conductive state, and switches the operating state of the first voltage converter from the first state to the second state. The power control system according to claim 8.

10. A specific load for driving the system, Further comprising an uninterruptible power supply device that temporarily stores the power supplied from the system power supply and supplies it to the load, the specific load, and the fuel cell auxiliary machine. The power control system according to claim 9.

11. The uninterruptible power supply device, A backup storage battery, A second voltage converter that adjusts the voltage of the system power supply and supplies it to the backup storage battery, A third voltage converter that adjusts the output voltage of the backup storage battery and supplies it to the load, the specific load, and the fuel cell auxiliary machine, The second voltage converter and the third voltage converter are constantly driven during system operation. The power control system according to claim 10.

12. Further comprising a fourth voltage converter that boosts the output voltage of the storage battery and outputs it to the first voltage converter, When the fourth voltage converter is stopped before the detection means detects a power failure of the system power supply, The controller, Starts the fourth voltage converter when the detection means detects a power failure of the system power supply, The capacity of the backup storage battery is set corresponding to the power required by the load, the specific load, and the fuel cell auxiliary machine from the time when the power failure of the system power supply is detected until the fourth voltage converter is started. The power control system according to claim 11.

13. The detection means is a current sensor disposed on the second voltage converter, The current sensor, The power control system according to claim 11, which detects the stop of the system power supply based on a change in the input / output current of the second voltage converter and transmits a detection signal to the controller.

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