UNINTERRUPTIBLE POWER SUPPLY

摘要

PROBLEM TO BE SOLVED: To provide an uninterruptible power supply which can switch between power feeding from an AC power supply and power feeding from an uninterruptible power supply without interruption and stably.

SOLUTION: In a lap period at the time of switchover between power feeding from a three-phase 4-wire non-insulated type inverter and power feeding from a commercial AC power supply, a zero-phase voltage control circuit 18 generates a zero-phase voltage directive so as to restrict a zero-phase current flowing in the inverter which is derived from an output current detection value of a current sensor, and generates a zero-phase current directive based on a deviation between the zero-phase voltage directive and a zero-phase voltage extracted from the output current detection value of the current sensor. An output current control circuit 22 adds the zero-phase current directive to a three-phase current directive which is output from an output voltage control circuit 16 to generate an output current directive for the inverter, and generates an output voltage directive for the inverter circuit based on a deviation between the output current directive and the output current detection value of the current sensor.

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