2 W Gate drive power supply design with PCB-embedded transformer substrate

Abstract

As silicon carbide (SiC) and gallium nitride (GaN) devices become commercially available nowadays, high switching frequency operation becomes a popular way to increase the power converter efficiency and power density. A key trade-off of these gains is the increasing electromagnetic inference (EMI) noise. In order to attenuate the EMI noise from the power loop into the auxiliary sources, the isolation capacitance in the isolated gate drive power supply is expected to be as small as possible. To this end, a gate drive power supply dedicated to driving two 650 V GaN devices in a phase leg is presented with a PCB-embedded transformer as substrate, achieving an ultra-low inter-capacitance 1.6 pF, high efficiency 83% and high power density 72 W/in3. The power supply uses active-clamp flyback topology, switching at 1 MHz with soft-switching technique, and owns two isolated outputs, generating 1 W each. A PCB-embedded transformer is proposed, whose toroidal core and three windings are fully embedded into PCB, using standard lamination process, in favor of high-integration converter design.