NOVEL DC-RAIL SOFT-SWITCHED 3-PHASE VOLTAGE-SOURCE INVERTERS

A family of de-rail soft-switched three-phase voltage-source inverters (VSI's) adopting the zero-voltage-transition (ZVT) or zero-current-tr ansition (ZCT) techniques are proposed in this paper, Adding an active switch on the de-rail makes the implementation of the ZVT and ZCT as easy as in a single-ended dc/dc converter, while true pulsewidth modul ation (PWM) operation is achieved by a modified space-vector modulatio n, As a result, these inverters can run at much higher switching frequ encies than the conventional hard-switched VSI's and with higher power density and efficiency, The operation and control strategy will be an alyzed, Implementation and experimental results of a prototype de-rail ZVT VSI, which is rated at 15 kVA and run at a switching frequency of 62.5 kHz, are presented, The measured efficiency with static loads re aches 93% under the input voltage of 400 V.