New drive concepts using single chip inverters

Emerging single chip inverters are very attractive for small variable speed drives but have a rather limited power handling capability. To maximize the power handling, square-wave excited high phase number induction motor drives are proposed which have significantly reduced inverter losses due to a low switching frequency. An analysis of the airgap MMF in high phase number induction motors and basic PSpice inverter model are used to verify these ideas. As an example an integrated drive design is presented that uses a six-phase induction motor and two Hitachi ECN3067 high voltage integrated circuit (HVIC) inverters for a demanding vacuum pump application. Results confirm reduced inverter losses and good drive performance.