Precise Gate Timing Control based on State Trajectory Analysis for 3.3kW Bidirectional AC/DC Converter

We propose a simple control method for AC/DC and DC/AC conversions with zero voltage switching (hereinafter, ZVS) operation, which we call Optimal Trajectory Control (hereinafter, OTC). In the OTC, precise gate timing is calculated using the analysis of the state trajectory model for the converter, with considering the resonance between the inductor and the output capacitance of the transistors. Since the gate timing is calculated precisely, the converter is operated without sensing zero current detection (hereinafter, ZCD) signal of the inductor current. The OTC makes more ideal ZVS waveforms compared with the case where the ZCD signal is used, since the latter case is subject to the delay of gate driving after ZCD signal is detected, while the former not. Employing the OTC, we demonstrate a ZVS operation of 3.3kW bidirectional totem-pole converter with the switching frequency of around from 200kHz to 700kHz, whose power density is as high as 5.3W/cm
³
. The peak efficiencies of the AC/DC and DC/ AC conversions are 98.5% and 98.4
^%
, respectively.