Steady-state analysis of series resonant converter using extended describing function method

This paper presents the steady-state analysis of series resonant converter (SRC) using the extended describing function (EDF) method. The EDF method is used to express non-linear terms of switching waveforms as linear descriptors to develop a linear model of the converter. The converter under consideration consists of a half-bridge inverter and a full-wave rectifier. The steady-state analysis in the frequency-domain is presented. The characteristics such as input-to-output-voltage transfer function and input impedance are obtained by first harmonic approximation of the converter state variables. Experimental results are given for a laboratory prototype of the SRC operating at 24 VDC input, 10 VDC output, output power of 15 W, and at a switching frequency of 110 kHz to verify the theoretical analysis.