JP6305830B2 - Uninterruptible power system - Google Patents

Description

  The present invention is an uninterruptible power supply device that continues to supply power to a load device regardless of the stop of power supply from a commercial AC power supply, and in particular, a combination of a system connected to a commercial power supply and a system connected to a fuel cell Relates to an uninterruptible power supply.

  Conventionally, as disclosed in Patent Document 1, as an uninterruptible power supply device that continues to supply power to load equipment even when power supply from a commercial power supply is stopped, a system that supplies AC power from the commercial power supply, and a fuel cell The DC power generated by the converter is converted to AC power with the same frequency and voltage as the commercial power supply system via an inverter and transformer, and this converted AC power is connected in parallel with the commercial power supply system so that power can be supplied to the load equipment. Blackout power supplies are known. Further, as disclosed in Patent Document 2, a fuel cell is provided in the uninterruptible power supply system, a fault in the AC power supply or a voltage drop in the power storage device is detected by a detector, and the fuel cell is activated at the time of detection. A system for supplying DC power from a fuel cell to an inverter has been proposed.

JP-A-7-336894 JP 2000-341879 A

  By using a fuel cell for the uninterruptible power supply as described above, it becomes possible to increase the backup time without increasing the capacity of the storage battery built in the uninterruptible power supply, but the fuel cell takes time to start up. Therefore, when using it for an uninterruptible power supply, it is necessary to supply power to the load equipment from the storage battery until the fuel cell is completely started after a power failure occurs. When switching between power supply from the storage battery, the power supply operation may become unstable. In particular, when a power failure and power recovery occur repeatedly in a short period of time with a commercial power source, for example, if power is restored after a power failure and then a power failure occurs again, the uninterruptible power supply receives the first power failure and fuel The battery is activated to supply power to the load device, and then the fuel cell is stopped when power is restored. For this reason, if a power failure occurs again after entering the fuel cell shutdown process, power must be supplied from the storage battery to the load device, and the storage battery that has been discharged once at the time of the first power failure will be used again. Cannot be avoided.

  In this way, the capacity of the storage battery is reduced due to repeated occurrences of power outages and power restorations, or the power outage is performed with a storage battery whose charging capacity is intentionally lowered as a safety measure during transportation attached to the uninterruptible power supply. If this occurs, there is a possibility that the power supply to the load device until the fuel cell is activated cannot be sufficiently performed from the storage battery, which may hinder the operation of the load device.

  The present invention has been made in view of the above-described problems, and an object thereof is to provide an uninterruptible power supply device having a stable power supply operation.

  (1) In order to achieve the above object, the present invention starts when an electric power supply from a commercial power supply is stopped in an uninterruptible power supply device comprising a combination of a power supply system connected to a commercial power supply and a fuel cell. A fuel cell that outputs direct current power, a storage battery that stores electric power supplied from the fuel cell and electric power supplied from a commercial power source, and alternating current power supplied from the commercial power source to direct current power to convert the fuel into the fuel cell A first AC / DC converter that supplies power for driving the battery, power for charging the storage battery, and power for external output to an external load device connected to the uninterruptible power supply, and a commercial power supply A second AC / DC converter that converts AC power into DC power and supplies it as external output power to an external load device connected to the uninterruptible power supply; the fuel cell; and the first A DC / AC inverter that converts DC power output from each of the AC / DC converter, the second AC / DC converter, and the storage battery into AC power and outputs the AC power, and a current value that is output from the fuel cell. A fuel cell state monitoring unit that determines the operating state of the fuel cell, and a control unit that controls the operation of the entire uninterruptible power supply, and the control unit determines the state of the fuel cell that is determined by the fuel cell state monitoring unit And the presence / absence of electric power supplied from a commercial power source, the on / off switching control of the operations of the first AC / DC converter and the second AC / DC converter is independently performed, and the charging of the storage battery is performed. An uninterruptible power supply characterized by controlling discharge operation is proposed.

  (2) When the proposed uninterruptible power supply (1) is in a state where power is supplied from a commercial power source and the fuel cell state monitoring unit determines that power generation is being performed by the fuel cell, By turning on the operation of the second AC / DC converter while turning off the operation of the first AC / DC converter and charging the storage battery with electric power generated by the fuel cell, It is desirable to maintain a state where power generation is performed.

  (3) The uninterruptible power supply proposed in (1) above supplies power from the storage battery to an external load device via the DC / AC inverter when power supply from a commercial power supply is stopped. The operation of the second AC / DC converter and the first AC / DC converter are kept on in the same state as before the power supply from the commercial power supply is stopped, and the fuel cell state monitoring unit supplies power in the fuel cell. When it is determined that power generation is performed in a possible state, the operation of the second AC / DC converter is kept on, while the operation of the first AC / DC converter is turned off, and the external load device It is desirable to supply power to the battery and charge the storage battery with power generated by the fuel cell.

  (4) Further, the proposed uninterruptible power supply (3) is configured such that when the power supply from the commercial power supply is stopped and the power is restored from the power failure state, the second AC / DC converter and the first AC / DC Charging with the power generated by the fuel cell until the charge rate of the storage battery reaches a predetermined ratio with respect to full charge while maintaining the operation of the DC converter in the state at the time of a power failure, the fuel cell state monitoring unit It is desirable to turn on the operation of the first AC / DC converter as soon as it is determined from the current value that the operation has completely stopped.

  (5) In the proposed uninterruptible power supply (3), the fuel cell state monitoring unit detects that the power generation operation of the fuel cell has stopped while the power supply from the commercial power supply is stopped. Is detected, the operation of the second AC / DC converter is kept on, while the operation of the first AC / DC converter is turned on, and the power supplied to the external load device is supplied by the power stored in the storage battery. It is desirable to do.

  (1) According to the proposed invention, as an AC / DC converter that converts AC power supplied from a commercial power source into DC power, it is connected to an external load device connected to the uninterruptible power supply and to the uninterruptible power supply. A first AC / DC converter that supplies power to each of the fuel cell and the storage battery provided in the uninterruptible power supply, and a second that only supplies power to external load devices connected to the uninterruptible power supply Two types of AC / DC converters are provided. Then, the operating state of the fuel cell determined from the value of the current input from the fuel cell to the uninterruptible power supply and the presence or absence of power supplied from the commercial power source to the uninterruptible power supply are grasped, and the first The AC / DC converter and the second AC / DC converter are independently switched on and off to perform power supply to the external load device and charge / discharge control of the storage battery. As a result, in a normal use state in which power is supplied to the external load device via the DC / AC inverter while receiving power supply from the commercial power supply, the charging current value to the storage battery is rated by the first AC / DC converter. The power supply to the external load device can be increased while the storage battery is protected to the following level. On the other hand, in a power outage state in which power supply from the commercial power supply is lost, for example, in a state where power is supplied from the storage battery to the external load device until the fuel cell is started, the first AC / DC converter is turned on. In this state, when the power supply is restored, the fuel cell that has been started by turning off the first AC / DC converter is now maintained. Thus, it is possible to perform control to maintain the operation as it is, and to stabilize the power supply operation to the external load device.

  (2) According to the proposed invention, power is supplied to an external load device via a DC / AC inverter while receiving power from a commercial power source, and the fuel cell is activated When power generation is performed, the operation of the second AC / DC converter is turned on to supply power to the external load device with the power supplied from the commercial power supply, and at the same time, the operation of the first AC / DC converter is performed. The battery is charged with the power generated by the fuel cell. As a result, the state in which the fuel cell is generating power can be maintained, and the operation of the uninterruptible power supply can be prevented from becoming unstable due to the fuel cell being repeatedly started and stopped more than necessary.

  (3) According to the proposed invention, when power supply from the commercial power supply is stopped and a power failure occurs, power is supplied from the built-in storage battery to the external load device via the DC / AC inverter, and the first AC / The operations of the DC converter and the second AC / DC converter are kept on as in the state before the power supply from the commercial power supply is stopped. Next, when the start of the fuel cell is completed and power generation is possible, the power generated by the fuel cell is generated by supplying power to the external load device and charging the storage battery by turning off the operation of the first AC / DC converter. Do by. As a result, the fuel cell can be kept in an activated state, and even when a commercial power failure and power recovery occur repeatedly in a relatively short time, the fuel cell is started and stopped each time. The power supply to the external load device and the charging to the storage battery can be stably performed without performing.

  (4) According to the proposed invention, when the commercial power supply recovers from the power failure state, the operations of the first AC / DC converter and the second AC / DC converter are maintained in the same state as at the time of the power failure. The fuel cell is activated, and charging is performed with the power generated by the fuel cell until the charge rate of the storage battery reaches a predetermined ratio. Then, when it is detected that the charging rate of the storage battery has reached a predetermined ratio and the operation of the fuel cell is stopped, the first AC / DC converter is switched on. As a result, when power is restored from a state where the commercial power supply has been cut off, charging is performed from the fuel cell until the charge rate of the storage battery reaches a predetermined ratio without immediately stopping the fuel cell. Even if a storage battery whose remaining charge is low due to a power failure is still not fully charged, power is supplied to the external load device from the fuel cell, eliminating the risk of excessive discharge of the storage battery. At the same time, it is possible to prevent a situation in which the power supply to the external load device is interrupted due to the battery being out of charge. Further, when it is detected that the charging rate of the storage battery has reached a predetermined ratio and the power generation operation of the fuel cell is stopped, the first AC / DC converter is immediately turned on, and the power of the commercial power supply is passed through the DC / AC inverter. Since it supplies to external load equipment, consumption of the electric power charged to the storage battery can be reduced as much as possible. As long as the power failure does not recur between the time when the commercial power supply is restored and the time when the charge rate of the storage battery is charged to a predetermined rate, the second AC / DC converter supplies power to the external load device from the commercial power supply. Therefore, efficient power supply with little power loss can be performed.

  (5) According to the proposed invention, when it is detected that the power generation operation of the fuel cell is stopped while the commercial power supply is in a power failure state, it is determined that the fuel cell has run out of fuel, and the first AC / DC converter is Is switched from the off state until on, and power is supplied to the external load device from the storage battery. Accordingly, the control operation for starting the fuel cell when the commercial power source is restored is not performed, and accordingly, power can be supplied to the external load device from the commercial power source immediately after the power restoration.

It is explanatory drawing which shows the whole structure of the uninterruptible power supply which concerns on this invention Example. It is a flowchart which shows operation | movement when a commercial power source is a normal state and the fuel cell 3 is in a power generation state. It is a flowchart which shows operation | movement at the time of a power failure in a commercial power source. It is a flowchart which shows operation | movement when a fuel cell runs out of fuel while the commercial power source is carrying out a power failure.

  Preferred embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is an explanatory diagram showing the overall configuration of an uninterruptible power supply according to an embodiment of the present invention. Reference numeral 1 denotes a commercial power supply, which supplies commercial AC 100-volt power to the uninterruptible power supply apparatus according to the embodiment of the present invention. Reference numeral 2-1 denotes a charging AC / DC converter (first AC / DC converter described in claims), which converts AC 100 volt power supplied from the commercial power source 1 into DC power, which will be described later. The fuel cell, the storage battery, the DC / AC inverter for external output, and the control unit are supplied. Reference numeral 2-2 denotes a load AC / DC converter (second AC / DC converter described in claims), which converts AC 100-volt power supplied from the commercial power source 1 into DC power for external output. Supply only to the DC / AC inverter. Reference numeral 3 denotes a fuel cell, whose output end is connected to the output side DC bus of the charging AC / DC converter 2-1. Reference numeral 4 denotes a lithium ion battery (storage battery described in claims), which is supplied from a commercial power source and converted via a charging AC / DC converter 2-1, and is generated by a fuel cell and supplied. On the other hand, when the commercial power supply 1 fails, the electric power charged in the battery is discharged. Reference numeral 5 denotes a DC / AC inverter, which is a DC power supplied from the charging AC / DC converter 2-1 and the load AC / DC converter 2-2, or a DC power supplied from the fuel cell 3, or a lithium ion battery. 4 receives the direct-current power discharged from 4 and converts it into 100-volt AC power and outputs it to the external load device 14. Reference numeral 6 denotes a control unit that controls operation of each device constituting the uninterruptible power supply according to the present embodiment. Reference numeral 7 denotes a fuel cell state monitoring unit, which is based on the value of the current generated and output by the fuel cell 3, but is in a stopped state where the fuel cell is not operating at all or is in the starting operation. A determination is made as to whether the power generation amount is in a starting state where the power generation amount is insufficient, or whether the power generation amount is sufficient. Reference numeral 13 denotes a power consumption monitor, which monitors the power consumption consumed on the output side of the DC / AC inverter 5 by detecting the current value flowing through the DC / AC inverter 5. 8-1 and 8-2 are heaters. The heater 8-1 is used as an auxiliary load when the power consumption of the external load device 14 is less than the minimum demand power (for example, 300 W) of the fuel cell when a power failure occurs and the external load device 14 performs power backup. Is done. There is a minimum amount of power consumption (minimum demand power) to maintain the operation state once the fuel cell is started. When the power consumption falls below this minimum demand power, the fuel cell stops and serves as an uninterruptible power supply. Therefore, when the power consumption of the external load device alone does not reach the minimum demand power, the power consumption monitoring unit 13 determines this and energizes the heater 8-1 through the control unit 6. . The heater 8-2 is an auxiliary heater, and when the power consumption of the external load device 14 and the heater 8-1 does not reach the minimum demand power of the fuel cell when a power failure occurs, the heater 8-2 is energized. Reference numeral 9 denotes an air conditioner that cools the inside of the uninterruptible power supply casing, and automatically operates / stops according to the set temperature. Further, the operating condition and abnormal condition of the air conditioner 9 are output to the control unit 6. Reference numeral 10 denotes a path switching relay, which feeds power supply paths to the heaters 8-1 and 8-2 and the air conditioner 9 directly from the commercial power supply 1 and AC power output from the DC / AC inverter 5. Switch between which route and which route to perform. A control operation unit 11 includes a liquid crystal monitor and a touch panel function, and performs status display, various settings, and maintenance operations of the uninterruptible power supply.

  Next, the operation of the embodiment of the present invention will be described with reference to FIGS. FIG. 2 is a flowchart showing an operation when the commercial power source 1 is in a normal state in the embodiment of the present invention. When the commercial power supply 1 is in a normal state where commercial alternating current 100 volt power is being supplied, the control unit 6 switches from the control unit 6 to the charging AC / DC converter 2-1 and the load AC / DC converter 2-2 as a normal mode. On the other hand, an ON signal for switching to the ON state is output, and an instruction signal for switching the path switching relay 10 to the commercial power source is output (S1). As a result, the commercial AC 100-volt power supplied from the commercial power source 1 is converted into DC power via the charging AC / DC converter 2-1 and the load AC / DC converter 2-2. / AC converted to 100 volt power through an AC inverter and supplied to the external load device 14 connected to the uninterruptible power supply. The lithium ion battery 4 is charged with power supplied from the commercial power source 1 via the charging AC / DC converter 2-1. Further, the heaters 8-1 and 8-2 and the air conditioner 9 are driven by electric power supplied from the commercial power source 1. In a state where commercial AC power is supplied from the commercial power source 1 (S2), the fuel cell status monitoring unit 7 determines the operating status of the fuel cell, and the fuel cell 3 is generating power. Upon confirmation (S3), the operation of the fuel cell charging mode is started and the on-state of the load AC / DC converter 2-2 is maintained as it is, while the charging AC / DC converter 2-1 is changed from on to off. Switching (S4). Thereby, the fuel cell 3 charges the lithium ion battery 4 from the state where the power supply to the external load device 14 and the charging to the lithium ion battery 4 are performed with the commercial AC 100 volt power supplied from the commercial power source 1. Switch to a state where power is generated.

  The operation of charging the lithium ion battery 4 with the power generated by the fuel cell 3 is continued until the charging rate of the lithium ion battery 4 reaches 70%. Until the charging rate reaches 70%, the energization control of the heaters 8-1 and 8-2 is performed so as to ensure the minimum demand power so that the fuel cell 3 does not repeat the start and stop in a short time. When the power consumption of the external load device 14 and the power consumed for charging the lithium ion battery 4 do not reach the minimum demand power of the fuel cell 3, the path switching relay 10 is switched to the output side of the DC / AC inverter 5. The energization switching control to the heater 8-1 and the heater 8-2 is performed by the control unit 6. In this way, the lithium ion battery 4 is charged in a state where the fuel cell 3 is continuously activated, and when the charging rate reaches 70%, an operation stop command is output from the control unit 6 to the fuel cell 3. When the power generation stop of the fuel cell 3 that has received the operation stop command is confirmed (S5), the operation returns to the normal mode, the charging AC / DC converter 2-1 is switched from OFF to ON, and the path switching relay 10 is switched. Is switched to the commercial power supply 1 side. As described above, when the commercial power source 1 is in a normal state and the fuel cell is in a power generation state, the operation of the fuel cell charging mode is started and the energization control of the heater is performed so as to ensure the minimum demand power of the fuel cell. The fuel cell is kept in an activated state without being stopped, and the lithium ion battery is charged. Therefore, it is possible to prevent the fuel cell from repeatedly starting and stopping, and to stably charge the lithium ion battery.

  Next, the operation when the commercial power supply 1 fails will be described based on the flowchart of FIG. When the commercial AC power supply from the commercial power source 1 is blacked out (circle numeral 1) during operation in the normal mode shown in FIG. 2 (S1), the processing operation shown in FIG. 3 is performed. When the supply of commercial AC 100 volt power is lost due to the occurrence of a power failure, the power supply to the external load device 14 is performed from the lithium ion battery 4 instead of the commercial power source 1, and the power backup operation is performed to prevent the power failure of the external load device 14. At the same time, the controller 6 outputs a start command to the fuel cell 3. At this time, the charging AC / DC converter 2-1 and the load AC / DC converter 2-2 are kept in the same ON state as in the normal mode shown in FIG. An instruction signal for switching to the output side of the inverter 5 is output (S10). Here, by setting the charging AC / DC converter 2-1 and the load AC / DC converter 2-2 to be in the same state as the normal mode, the commercial AC 100 V immediately after the commercial power source 1 is restored. It can be restored with electric power.

  Next, the operating state of the fuel cell is judged by the fuel cell state monitoring unit 7 and when it is confirmed that the fuel cell is generating power (S11), the operation of the fuel cell backup / charge mode is started ( S12). In this operation mode, the load AC / DC converter 2-2 is kept on, while the charging AC / DC converter 2-1 is turned off, and the path switching relay 10 is connected to the DC / AC inverter 5. Holds the state connected to the output side. As a result, both the power supply to the external load device 14 and the charging to the lithium ion battery 4 are switched to a state where the power generated by the fuel cell 3 is used, and the heater 8- Energization control to 1 and 8-2 is performed. Even when the commercial power source 1 repeats power recovery and power outage, the fuel cell does not start / stop each time, and the start-up state is continuously maintained to stably supply power to the external load device. It is.

  When the commercial power source 1 recovers (S13), the fuel cell shutdown transition is made while the charging AC / DC converter 2-1 and the load AC / DC converter 2-2 are kept in the same state as the fuel cell backup / charging mode. The mode operation is started (S14). In this operation, the fuel cell 3 is continuously operated, and charging is performed with the electric power generated by the fuel cell 3 until the charging rate of the lithium ion battery 4 reaches 70%. The reason why the fuel cell is operated even after the commercial power supply is restored is to recover the charging rate of the lithium ion battery in case a power failure occurs again after the power restoration. If the power for charging is switched to the commercial power source 1 without fully recovering the charging rate of the lithium ion battery, the fuel cell stops, and if a power failure occurs immediately after that, the remaining charge of the lithium ion battery is low. Since power is supplied to the external load device from the lithium ion battery, there is a risk that sufficient backup time cannot be guaranteed. It restores the battery charge. Therefore, as already described, until the charging rate of the lithium ion battery reaches 70%, the heaters 8-1 and 8- are used to secure the minimum power demand so that the fuel cell 3 does not repeat starting and stopping in a short time. The energization control to 2 is performed. In order to prioritize recovery of the charging rate of the lithium ion battery, power is supplied to the external load device 14 from the commercial power source 1 via the load AC / DC converter 2-2 and the DC / AC inverter 5. Commercial AC 100 volt power is applied. In this way, the lithium ion battery 4 is charged in a state where the fuel cell 3 is continuously activated, and when the charging rate reaches 70%, an operation stop command is output from the control unit 6 to the fuel cell 3. When the power generation stop of the fuel cell 3 that has received the operation stop command is confirmed (S15), the operation returns to the normal mode, the charging AC / DC converter 2-1 is switched from OFF to ON, and the path switching relay 10 is switched. Is switched to the commercial power supply 1 side.

  Next, based on the flowchart of FIG. 4, the operation when the fuel cell runs out of fuel while the commercial power source 1 is out of power will be described. When the fuel cell state monitoring unit 7 detects that the power generation of the fuel cell is stopped while operating in the fuel cell backup / charge mode shown in FIG. 3 (circle numeral 2), the fuel in the fuel cell is exhausted. The power recovery standby mode is started (S22). In this operation, while the load AC / DC converter 2-2 is kept in the on state, the charging AC / DC converter 2-1 is switched from the off state to the on state, and the path switching relay 10 is connected to the DC / AC inverter 5 The state connected to the output side of is maintained. The power supply to the external load device 14 is performed from the power stored in the lithium ion battery 4. Since the load AC / DC converter 2-2 is kept on and the charging AC / DC converter 2-1 is switched from the off state to the on state, when the commercial power source 1 recovers ( S23), it is possible to immediately output the power supplied from the commercial power source 1 to the external load device 14 through the load AC / DC converter 2-2 and the charging AC / DC converter 2-1. When the fuel cell runs out of fuel and shifts to the power recovery standby mode operation, when there is no power recovery of the commercial power source 1 and the remaining charge of the lithium ion battery 4 reaches the lower limit value in the system operation. (S23), the system stop processing operation as the entire uninterruptible power supply is executed and the process ends.

  The uninterruptible power supply according to the present invention is a device that continuously supplies power to a load device at the time of a power failure, and in particular, by providing both a storage battery and a fuel cell, a long-time power backup operation for the load device is performed. It can be used for applications to be performed.

1 Commercial power supply 2-1 Charging AC / DC converter (first AC / DC converter)
2-2 Load AC / DC converter (second AC / DC converter)
3 Fuel cell 4 Lithium ion battery (storage battery)
5 DC / AC inverter 6 Control unit 7 Fuel cell state monitoring unit 8-1 Heater 8-2 Auxiliary heater 9 Air conditioner 10 Path switching relay 11 Control operation unit 13 Power consumption monitoring unit 14 External load device

Claims (5)

In an uninterruptible power supply consisting of a combination of a power supply system connected to a commercial power source and a fuel cell,
A fuel cell that starts when the power supply from the commercial power supply stops and outputs DC power; and
A storage battery for storing electric power supplied from the fuel cell and electric power supplied from a commercial power source;
AC power supplied from a commercial power source is converted into DC power to drive power to the fuel cell, charge power to the storage battery, and power for external output to an external load device connected to the uninterruptible power supply A first AC / DC converter to supply;
A second AC / DC converter that converts AC power supplied from a commercial power source into DC power and supplies it as external output power to an external load device connected to the uninterruptible power supply;
A DC / AC inverter that converts DC power output from each of the fuel cell, the first AC / DC converter, the second AC / DC converter, and the storage battery into AC power and outputs the AC power;
A fuel cell state monitoring unit that determines an operating state of the fuel cell based on a current value output from the fuel cell;
A control unit that controls the operation of the entire uninterruptible power supply,
The control unit grasps the state of the fuel cell determined by the fuel cell state monitoring unit and the presence / absence of power supplied from a commercial power source, and the first AC / DC converter and the second AC / DC An uninterruptible power supply, wherein the operation of the converter is independently controlled to be switched on and off, and the charge / discharge operation of the storage battery is controlled.   2. The uninterruptible power supply according to claim 1, wherein when the electric power is supplied from a commercial power source and the fuel cell state monitoring unit determines that the fuel cell is generating electric power, By turning on the operation of the AC / DC converter while turning off the operation of the first AC / DC converter and charging the storage battery with the power generated by the fuel cell, power is generated by the fuel cell. An uninterruptible power supply characterized by maintaining   2. The uninterruptible power supply apparatus according to claim 1, wherein when power supply from a commercial power supply is stopped, power is supplied from the storage battery to an external load device via the DC / AC inverter, and the second AC / DC converter is provided. And the operation of the first AC / DC converter is kept on as in the state before the power supply from the commercial power supply is stopped, and the fuel cell state monitoring unit generates power in a state where the fuel cell can supply power. If it is determined that the operation is being performed, the operation of the second AC / DC converter is kept on, while the operation of the first AC / DC converter is turned off to supply power to an external load device and An uninterruptible power supply characterized by charging a storage battery with electric power generated by a fuel cell.   4. The uninterruptible power supply apparatus according to claim 3, wherein when the power is restored from a power failure state in which power supply from a commercial power supply is stopped, the operations of the second AC / DC converter and the first AC / DC converter are interrupted. The battery is charged with the electric power generated by the fuel cell until the charge rate of the storage battery reaches a predetermined ratio with respect to the full charge while maintaining the state of the time, and the operation of the fuel cell is completely stopped by the fuel cell state monitoring unit An uninterruptible power supply characterized by turning on the operation of the first AC / DC converter as soon as it is determined from the current value.   The uninterruptible power supply apparatus according to claim 3, wherein when the fuel cell state monitoring unit detects that the power generation operation of the fuel cell is stopped while being in a power failure state in which power supply from a commercial power supply is stopped, The operation of the second AC / DC converter is kept on, while the operation of the first AC / DC converter is turned on, and the power supply to the external load device is performed by the electric power stored in the storage battery. Uninterruptible power system.

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