A review and performance evaluation of control techniques in resonant converters

This paper presents different control techniques that are frequently applied in the resonant converters. The paper first discusses each control technique and then gives quantitative comparison of such techniques to highlight their merits and demerits. A full bridge series parallel resonant converter with an inductive output filter is taken as a study case for this comparative study. The different control techniques include: variable frequency (VF) control, phase shift modulation (PSM) control, self-sustained oscillation (SSOC) control, self-sustained phase shift modulation (SSPSM) control, and optimal control (sometimes called linear quadratic regulator LQR). The comparative study illustrates the effect of each controller on the converter rating, transient response, the allowable range of zero voltage switching (ZVS), and the range of the switching frequency variation. It is shown in the paper that the traditional linear controllers offer good performance at one operating point only while the nonlinear controllers, can improve robustness, reliability, and dynamic performance over a wide range of operation.