Optically Triggered Self-Adaptive Zero Voltage Switching

Zero voltage switching (ZVS) is useful to increase power electronics efficiency but difficult to achieve due to the nonlinear parasitic capacitance of the power semiconductors and varying load current. This letter proposes a self-adaptive ZVS method by using the intrinsic electroluminescence (EL) property of SiC mosfets to automatically adjust the switching frequency in every switching cycle to retain the optimal ZVS in varying load current. A sensing circuit is developed to digitally utilize the EL to trigger ZVS and embodied in a customized PCB-embedded half-bridge power module. Experimental results demonstrate the effectiveness of the proposed optically triggered self-adaptive ZVS in a Buck converter. The proposed method is compatible with conventional PWM gate drives for various power electronic devices and applications.