| 摘要 |
PROBLEM TO BE SOLVED: To suppress an overcurrent generated in a V-phase or a neutral stabilization circuit, at the time a V-connection type inverter is started. SOLUTION: The V-phase among three phases of an AC power supply 20 is connected directly to the V-phase of a load 8 through the neutral point of DC power supplies 1a and 1b to construct the V-connection type converter or inverter of an uninterrupted power supply device. Further, a middle point between switching devices 3e and 3f is connected to the V-phase via a reactor 5e to construct a neutral stabilization circuit. In order to start the inverter when a power is not supplied to the load 8, the inverter is started when a V-phase current is zero, i.e., when the phases of Vuw and Vvw are equal or very close to each other. In order to start the inverter when the V-phase is switched by a bypass switch 24, the inverter is started at a phase when the current of the reactor 5e is below an overcurrent level. |
