A turn-on switching losses study in a ZCT soft-switching converter

This paper presents a mathematical approach of calculating the turn-on switching losses in a ZCT soft-switching converter. In theory, the ZCT scheme enables all main switches and auxiliary switches to be turned on and off under zero-current conditions. For the diode reverse-recovery problem can not be eliminated at the IGBT turn-on transition even though the diode current is resonated to zero, and the switching losses in IGBT and diode can not be ignored. Instantaneous voltage and current waveforms of the ZCT soft-switching converter are studied and linearized, and a diode charge-control model is employed to formulate the turn-on switching losses equations. The proposed method is verified by experimental results using a three phase ZCT soft-switching converter.