A sampled-data reduced order dynamic model for a self-sustained series-parallel resonant converter

Resonant converters are well known in many industrial applications due to their high operating frequency and lossless switching. The series parallel hybrid type converter has been known as the most promising resonant topology, as it provides a considerably wide operating range with optimized ratings of components. Unfortunately, it has a wide range of operating frequency under the conventional variable frequency control (VF). The self-sustained oscillation control (SSOC) technique was proposed in 1997 in order to further reduce the range of regulating frequency necessary for zero voltage switching (ZVS) and consequently optimize the converter design to achieve a more compact size and consequently lower cost. However, optimizing the converter design at such high frequencies is not an easy task. The first step for achieving this objective is to have a sound and accurate mathematical model for the converter. This paper describes a simple fifth-order dynamic model with a more systematic approach based on the sampled data technique; it has the advantages of being more accurate, easily computed, and has a lower order than its continuous time predecessor found in [1], which was of a seventh order model. In this paper, the complete analysis, modeling, and design of the series parallel resonant converter with an inductive output filter under the SSOC is investigated and verified.