A Very-High-Frequency Isolated Gate Driver Power Supply Using Solid Dielectrics for Medium Voltage SiC MOSFETs

This paper presents a very-high-frequency (VHF) isolated gate driver power supply (GDPS) using the solid dielectrics for the medium-voltage (MV) SiC MOSFETs. The resonant flyback converter operating at a VHF range enables the coreless transformer with a simplified insulation requirement. An insulation scheme using the solid dielectrics is proposed. The solid dielectric of printed-circuit board (PCB) is utilized as the isolation barrier, and the silicone gel potting is applied to improve surface flashover properties. The VHF operation and proposed insulation scheme achieve a compact GDPS size of 36 mm × 20 mm × 6 mm, an insulation voltage of > 12 kV rms, and a small common-mode (CM) capacitance of 3.2 pF. Experimental results are provided to validate the effectiveness of proposed insulation scheme and the performance of developed GDPS.

I. Introduction

In recent years, medium-voltage (MV) SiC MOSFETs have gained the increased attention due to their low switching loss, high switching frequency, and high-temperature endurability [1]. However, the high operating voltage and high dv/dt switching transients of MV SiC MOSFETs pose challenges for the isolated gate driver (GD) power supply (GDPS) design, where a high insulation strength and a small common-mode (CM) capacitance are required accordingly [2]–[3].