High dv/dt immunity, high insulation voltage, ultra-compact, inductive power supply for gate-drivers of wide-bandgap semiconductor switches

Abstract

The high dv/dt transient speed of wide-bandgap (WBG) semiconductor switches can generate common-mode current of considerable magnitude, which can distort the gating signals. An isolated power supply is required for gate-driver circuits to prevent the faulty operation of the switches. However, an isolation capacitance of several pF between the gate-driver circuit and the main control circuit induces a common-mode current, which is sufficiently large to distort the switching signals. In this study, an isolated power supply with a high dv/dt immunity, ultra-compact size, and high insulation voltage is developed using inductive power transfer (IPT) coils. A parameter design method for a series-parallel compensated IPT system that can achieve a load-independent output voltage is presented. In addition, a novel design for I-core coils is proposed using finite element analysis results. An isolation capacitance of 1.6 pF between the primary and secondary coils was achieved over a 4 mm air gap. The dimensions of the IPT coils were 38 x 22 x 15 mm(3). The measured coil-to-coil and DC-to-DC efficiencies at an output power of 12 W were 95% and 87%, respectively.