Analysis on Static Current Sharing of N-Paralleled Silicon Carbide MOSFETs

Abstract

The influences of on-resistances and parasitic elements on the static current sharing of N-paralleled discrete silicon carbide (SiC) MOSFETs are analyzed in this paper. First of all, the limitation of self-balancing effect of MOSFETs caused by the positive temperature dependent on-resistance is quantitatively analyzed. From a statistical analysis, the current sharing distribution according to the spread of on-resistances is presented, which helps to screen the proper devices based on the current sharing requirement. Furthermore, a general circuit model is proposed to analyze the effect of inevitable circuit parasitic elements on current sharing with a given current slew rate. With the recursive circuit model, current imbalance contributed by parasitic resistances and inductances can be separately calculated, which can be used to guide the hardware design to improve current sharing in a real converter. The theoretical analysis is verified by experimental results.