A low-cost three-phase zero-current-transition inverter with three auxiliary switches

Most existing three-phase soft-switching inverters with less than six auxiliary switches have fundamental drawbacks in performance. Those with six auxiliary switches have potentially good performance, but with penalties of high cost and large space. This paper proposes a new zero-current-transition (ZCT) inverter topology that reduces the number of auxiliary switches from six to three, without increasing the device power rating or requiring any additional components, for electric vehicle propulsion. With considerable reduction in cost and size, the performance of existing ZCT inverters remains as desired. At main switches and auxiliary switches are turned off under zero-current conditions, and main switches are turned on under a near zero-current condition. Meanwhile, the ZCT implementation does not modify normal space vector modulation (SVM) schemes. A 10 kW prototype has been built and tested to verify the fundamental principle and simulation results