Evaluation and Suppression Method of Turn-Off Current Spike for SiC/Si Hybrid Switch

Abstract

SiC MOSFET/Si IGBT (SiC/Si) hybrid switch usually selects the gate control pattern that SiC MOSFET turns on earlier and turns off later than Si IGBT, with the aim of making the hybrid switch show excellent switching characteristics of SiC MOSFET and reduce switching loss. However, when SiC MOSFET turns off, the fast slew rate of drain source voltage causes the current spike in Si IGBT due to the effects of parasitic capacitance charging and carrier recombination, which will produce additional turn-off loss, thus affecting the overall efficiency and temperature rise of the converter. Based on the double pulse test circuit of SiC/Si hybrid switch, the mathematical model of the turn-off transient process is established. The effects of the remnant carrier recombination degree of Si IGBT, the turn-off speed of SiC MOSFET and the working conditions on the turn-off current spike of hybrid switch are evaluated. Although adjusting these parameters can reduce the turn-off current spike somewhat, additional losses will be introduced. Therefore, a new method to suppress the turn-off current spike is proposed to balance the power loss and current stress.INDEX TERMS SiC MOSFET/Si IGBT, hybrid switch, current spike, suppression method

Accurate current measurement method in high frequency hybrid switch test and application

“…Fu et al proposed the inductive current overshoot calculation model of HyS and related driver designs [7], [8]. Qin et al explored the IGBT current spike behaviors with loop inductance involved [9,10]. Besides, Funaki discussed the ringing oscillation caused by parasitic inductance in Si/SiC devices tests [11,12].…”