Research on the Optimal Control Timing of ZVS-QSW

Abstract

This article introduces a research method aimed at achieving optimal control timing for the zero-voltage quasi-square wave switch (ZVS-QSW) in a silicon carbide buck converter across a wide range. The method establishes the correlation function between optimal control timing parameters and load current through composite segmented curve fitting to the plane of the ZVS-QSW state over the entire operating range. It also compensates for the charge change on the filter capacitor to determine the load current at the corresponding operating point. By collecting the input/output voltages and load currents and substituting them into the correlation function, the optimal timing parameters for achieving ZVS-QSW can be determined online. The proposed method is validated on a silicon carbide buck converter prototype with an input voltage of 400 V. ZVS-QSW can be achieved in the conversion ratio range of 0.1-0.9. Consequently, the proposed method not only reduces the difficulty of inductance current measurement but also simplifies and visualizes the timing control of the converter.INDEX TERMS Curve fitting, digital control, quasi-square wave, silicon carbide, zero-voltage switching.