A comparative study of a family of zero-current-transition schemes for three-phase inverter applications

This paper explores the fundamental properties of a family of zero-current-transition (ZCT) inverters in a systematic and comparative approach. The inverters studied include several schemes for a circuit configuration with six auxiliary switches and one topology that requires only three auxiliary switches. First, a simplified equivalent circuit is presented to unify common traits of ZCT commutations and their design criteria. Mechanisms for achieving zero-voltage turn-on in ZCT inverters are investigated. Then, with the visual aid of state planes, behaviors of individual inverters, including switching turn-on and turn-off conditions, circulating energy, and device/component stresses, are analyzed against the simplified equivalent circuit. Finally, a comparison of major features is conducted. Both simulation and experimental results are provided for verification.