Construction of a Planar Transformer With Low Common-Mode Capacitance for Medium-Voltage Isolated Gate-Driver Power Supply

The isolated gate-driver power supply is one of the crucial components inside the medium-voltage (MV) power converter, which provides galvanic isolation featuring low common-mode (CM) capacitance and high dv/dt immunity. Therefore, the design of the isolation transformer needs to be customized. However, none of the known papers have proposed a convenient transformer assembly method. For this purpose, an easy-to-manufactured planar transformer for MV gate-driver power supply is proposed in this paper. The designed isolation transformer has been tested at 7 kV DC voltage and measured the CM capacitance of 0.628 pF. Thus, the voltage isolation capability and low CM capacitance characteristics of the transformer have been verified.