Half-cycle sampled discrete model of series-parallel resonant converter with optimized modulation

Because of low switching losses and wide operation range, series-parallel resonant converter with optimized modulation is attractive. There are three major modeling methods for resonant converters, including approximation method, extended describing function method, and sampled-data method. Approximation method and extended describing function method are simple but relatively inaccurate on heavy load conditions. Sampled-data method requires many computation resources which limits the utilization in control algorithm. A low computational cost and relatively accurate model, half-cycle sampled discrete model is proposed in this contribution. The model describes the behavior of converters with slow-varying variable and assumes variables constant in every half cycle. The model is verified by circuit simulation and experiments.