Implementation of a three-level ZVZCS converter with passive snubber

Abstract

A soft switching three-level pulse-width modulation converter with the functions of low primary circulating current loss, low output current ripple and zero voltage switching of switches is presented for industry power units. Two circuit cells are adopted in the proposed converter to reduce the current rating of passive components at the secondary side. Passive snubber circuit is adopted to generate a positive rectified voltage instead of zero voltage at the secondary side. The positive rectified voltage is reflected to the primary side to reduce the circulating current during the freewheeling interval. Hence, the circulating current loss is improved in the proposed converter. Finally, experimental results based on a 1.44kW prototype circuit are presented to verify the effectiveness of the proposed converter.