Frequency Tracking Burst-Mode PDM-controlled Class-D Zero Voltage Soft-Switching Resonant Converter for Inductive Power Transfer Applications

A newly developed prototype of zero-voltage soft-switching (ZVS) high-frequency resonant for inductive power transfer (IPT) applications is presented in this paper. By adopting the burst mode pulse-density-modulation (PDM) scheme with resonant frequency tracking, the load power can be continuously regulated under the conditions of full-range soft-switching due to the undamped resonant currents through the coils, thereby the current surges which appears with the conventional PDM scheme can be eliminated effectively. The essential performances on the output power regulation and soft-switching operations are demonstrated in experiment using a class of 400 W-500 kHz prototype, and the validity is evaluated from the practical point of view.