Novel dynamical modeling for series-parallel resonant converter

Extended describing function method is one of the commonly applied state-of-the-art methods for dynamical modeling of series-parallel resonant power converters. Thanks to the relative good sinusoidal voltage waveform across the parallel capacitor C_p it has a good modeling accuracy under light and medium load conditions. However, under heavy load condition this method becomes inaccurate due to the distortion of the voltage across C_p. Sampled-data method provides a much higher modeling accuracy, but its modeling complexity and computational effort are too high. In this contribution a novel dynamical model for series-parallel resonant converter is proposed, which is simpler than sampled-data method, but provides a considerable enhancement on modeling accuracy. Large- and small-signal behaviors predicted by the novel dynamical model are verified by circuit simulation.