18 kV Partial Discharge Free Medium Voltage Insulated Gate Driver Power Supply for SiC-Based Power Conversion System

With the adoption of the medium voltage power conversion systems, arises the requirement for capable devices and their drivers which have been fulfilled by silicon carbide (SiC) MOSFETs and their respective drivers which have been powered by commercial power supplies in the past. For such high voltages, insulation requirement increases while maintaining a small form factor for the increased power density of the overall converter. Traditionally, the size of the commercial (GDPS) is limited due to wire wound magnetics whose size must be increased to cater to high insulation ratings or needs to be potted with epoxy resin which makes the solution very bulky. The proposed solution comprises a PSFB converter driving a medium-voltage (MV) current transformer (CT), and a secondary circuit with a hysteresis controller to regulate the output voltage. A 1 MHz, 16 W PCB-winding-based GDPS is designed and built for SiC-based MV power converter, achieving a partial-discharge inception voltage (PDIV) higher than 18 kV rms, with a very small form factor of about 5.2 in³. The MV CT can withstand a dielectric strength test (or Hi-pot) test at 41 kV DC for 1 minute without showing any signs of insulation breakdown.