High-Density Current-Transformer-Based Gate-Drive Power Supply With Reinforced Isolation for 10-kV SiC MOSFET Modules

With features such as faster switching frequency and higher breakdown voltage, wide bandgap power devices are key enablers to address the increasing demand for higher power density and higher efficiency in future medium-voltage converters. The 10-kV SiC MOSFET is one of such devices; yet, to fully utilize its benefits, a gate-drive power supply capable of meeting the necessary insulation (voltage) and isolation (dv/dt voltage slew rate) requirements is needed. To this end, this article presents the complete design and optimization of such a power supply meeting four critical objectives: 1) high power density with high-voltage (HV) insulation; 2) minimum input-output capacitance; 3) fault ride-through capability; and 4) good voltage regulation. To this end, a GaN-based inductor-capacitor-capacitor-inductor (LCCL)-LC resonant converter switching at 1 MHz was used to produce a resonant current source and to supply multiple isolated loads (gate-drivers) through the single-turn primary winding loop. Experimental results are shown demonstrating the attained power density (6.3 W/in3), input-output capacitance (1.67 pF), peak efficiency (86.0%), short- and open-circuit fault withstanding capacity, and insulation rating (partial discharge inception voltage of 12 kV).