Comprehensive evaluation on Si/SiC hybrid switch including single-pulse avalanche and short-circuit robustness

In this paper, a comprehensive evaluation on silicon/silicon carbide (Si/SiC) hybrid switch is made by experimental tests in terms of both electrical performances and robustness under extreme stresses. Based on the optional turn-on and turn-off delay times under the efficiency controlling mode obtained from the double-pulse test (DPT), both nondestructive and destructive single-pulse avalanche testing are conducted on the Si/SiC hybrid switch as well as on the two fresh discrete device branches inside the hybrid switch. In addition, the avalanche voltage, critical avalanche energy, and peak avalanche current, which can intrinsically characterize the unclamped-inductive-switching (UIS) avalanche characteristics, were carefully examined. In this way, the physical factors that dominate the UIS characteristics of the hybrid switch, thus limiting its single-pulse avalanche withstand capability, are specifically and comprehensively identified, the underlying physical mechanisms are analyzed and revealed in depth, and how the gate controlling sequence affects the UIS characteristics of the hybrid switch is extensively investigated. We additionally carried out short-circuit (SC) tests under the fault-under-load (FUL) condition and applied a parallel in-depth analysis to determine experimentally which branch determines the SC withstand capability of the hybrid switch. Our experimental study indicates that, for both SC robustness and single-pulse avalanche capability, the limiting factor is one single device branch within the two parallel discrete devices, and the UIS behavior is sensitive to the variation of the gate turn-off delay time T off_delay . The study conducted in this paper not only provides deep academic insights into the electrical performance and reliability of the Si/SiC hybrid switch, but also provides fundamental theoretical principles as well as technical evidence for the hybrid switch towards its more efficient and long-term reliable applications in the industrial field.