New Screening Method for Improving Transient Current sharing of Paralleled SiC MOSFETs

Abstract

In this paper the effect of the spread of SiC MOSFET device parameters on transient current sharing is investigated. To aid in this investigation, the coefficient of variation is proposed firstly and then used as the evaluating specification for the spread of device parameters. Two main factors which affect transient current sharing, threshold voltage and trans-conductance, are analyzed based on transfer characteristics of MOSFET. Experimental studies show that threshold voltage has larger spread than trans-conductance. Moreover, there is mutual compensation of the effects of threshold voltage and trans-conductance on SiC MOSFET transient current sharing. Finally, to improve transient current sharing of paralleled devices, this paper proposes the transfer curve screening method. Compared to the traditional single parameter screening method, experimental results show that the current imbalance rate with proposed method is only 3.5%, whereas it reaches 26% with traditional method.