Galvanic isolation system for multiple gate drivers with inductive power transfer — Drive of three-phase inverter

Medium-voltage motor drive systems, medium-voltage inverters, which have an input voltage and an output voltage of 3.3 kV or 6.6 kV, are widely used in industry applications. In the medium-voltage inverter, robust galvanic isolation among a control circuit and each gate drive supplies is required in order to drive high-voltage switching devices. In present, a transformer, which is designed to satisfy the safety standards, provides galvanic isolation. However, transformers prevent cost reduction of the isolation system. In this paper, the galvanic isolation system using only printed circuit boards are proposed. Moreover, a three-phase inverter is driven using the isolation system in order to confirm the utility of the isolation system. The proposed system transmits power from the transmitting board to six receiving boards using each transmitting coils made on the printed circuit boards. The air gap among the printed circuit boards assumes galvanic isolation. From the experimental results, it is confirmed that the three-phase inverter can be driven by the proposed galvanic isolation system.