THREE-LEVEL INVERTER DEVICE

摘要

PROBLEM TO BE SOLVED: To enhance conversion efficiency and operation stability by controlling the resonance current of the DC bus of a three-level inverter device. SOLUTION: This device controls a resonance current going through a middle potential bus by interposing resonance control resistors 6a-6d in the middle potential bus C between the DC neutral point potential terminal and the DC link part of a multiphase inverter. This can arrange the resonance frequency of the DC link part not to accord with the switching frequency of a PWM by interposing reactors 7a and 7b for resonance control at least either between the DC positive potential terminal of the multiphase inverter and the DC positive potential bus, or between the DC negative potential terminal of the above multiphase inverter and the DC negative potential bus, thereby setting the resonance frequency properly.