A generalized zero-current-transition concept to simplify three-phase soft-switching inverters

A concept of a generic half-bridge zero-current-transition (ZCT) cell is developed, which employs one auxiliary switch and one LC resonant tank to assist switching transitions. Application of the concept leads to the discovery of a family of simplified soft-switching inverters, including two-level inverters using only three auxiliary switches and three-level inverters using six auxiliary switches. Unlike existing techniques, these inverters require no modification to normal space-vector modulation (SVM) schemes, and in the meantime achieve soft commutation for all main switches, diodes and auxiliary switches at all operation modes. The three-level ZCT inverters are analyzed in detail, based on PSPICE simulation using actual device models and including parasitic inductance. Hardware implementation and experimental results are provided.