Current-Transformer Based Gate-Drive Power Supply with Reinforced Isolation

Wide-bandgap power semiconductors are enabling power electronics to meet higher power density and efficiency thanks to their fast switching frequency and high blocking voltage. In the high-power area, 10 kV, 240 A SiC MOSFET module has recently become a candidate for medium-voltage converters. The particular device characteristics require both high insulation and isolation strength from its gate driver power supply. To address that, this paper presents a complete design and optimization of a high-density 20 kV isolated power supply. Four objectives of high density under high-voltage insulation, low input-output coupling capacitance, fault ride-through, as well as fair voltage regulation and efficiency, have been achieved. The power supply leverages GaN-based LCCL-LC resonant circuit that produces a 1 MHz resonant current source to take multiple isolated loads. Experimental results show 1.67 pF input-output capacitance, 86% efficiency at rated load, and excellent resiliency at load short-circuit fault.