Small Signal Modeling of Series Resonant Converter based on State-plane Analysis

In this paper, small signal modeling of series resonant converter (SRC) operating under variable frequency modulation is presented. Noting that the existing small signal models are of higher order and mathematically complex, a reduced order model is proposed to make the control loop design easy. Both time-domain-based exact state plane analysis and averaging technique of an electrical variable are adopted to derive control-to-output transfer functions of SRC. Accuracy of the proposed approach is validated using LTSPICE simulation.