Dual-Output Isolated Gate Driver Power Supply for Medium Voltage Converters using High Frequency Wireless Power Transfer

With the recent advancement in semiconductor technology, SiC Mosfets with a high blocking voltage, e.g. 10kV, and a high switching frequency, e.g. 100kHz, has been fabricated and bring great opportunities for medium voltage (MV) converters to have a high power density while achieving simple architectures compared to conventional multilevel converters. However, the high blocking voltage and high switching frequency results in a high dV/dt during switching transients, causing a serious common-mode (CM) current noise that circulates through gate driver (GD) and control circuit, which can interrupt the operation of the MV converters. Therefore, in order to ensure a proper operation of the MV converters, gate driver power supplies (GDPSs) should have a low coupling capacitance as well as a high voltage insulation. This paper presents a compact dual-output isolated power supply (PS) powering GD circuits of medium voltage (MV) converters, which satisfies the two above requirements. The impact of rectifier and shielding on the coupling capacitance is analyzed in details. The proposed PS is based on the principle of wireless power transfer (WPT) with one transmitter (Tx) coil powering two receiver (Rx) coils simultaneously at the operation frequency of 4MHz. These coils are fabricated on a single PCB. Measurements are performed to validate the designed gate driver power supply (GDPS) and show that it achieves a compact size and a high voltage isolation while maintaining a low coupling capacitance.