Patent ID: 8228699

Claim:
A power converting apparatus comprising: two sets of half-bridge inverters connected between positive and negative terminals of a DC power supply, each set of half-bridge inverters including two series-connected switching devices; single-phase inverters connected in series with individual AC output lines of said two sets of half-bridge inverters; and two series-connected capacitors for dividing a voltage of said DC power supply which is a DC input of said half-bridge inverters, wherein, output terminals of said individual single-phase inverters are connected to two ungrounded phases of a three-phase power system of which one phase is grounded, an intermediate point of said two series-connected capacitors is connected to a neutral point of AC outputs from said single-phase inverters of said two phases, and the intermediate point is connected to the one grounded phases of said power system, and each of said half-bridge inverters is caused to output voltage pulses of which frequency is same to that of a system voltage and said individual single-phase inverters are controlled by PWM control operation to make up for a voltage insufficiency from the system voltage.