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Steady-state analysis of soft-switching converters is discussed in this paper. Finding the steady-state solution of soft-switching converters by means of start-up transient simulation may involve onerous computations and convergence failure, because of the mix of fast and slow natural frequencies determined respectively by the presence of soft-switching Lr-Cr cells elements and bulky L-C filter elements. The numerical method proposed in this paper shows high reliability and fast convergence, thanks to the adoption of an interval analysis based technique for the detection of commutations and of a compensation theorem based technique for the analysis of commutations. Some examples of steady-state analysis of two dc-dc converters, an inverter and a power factor corrector are presented to highlight the good performances of the simulation algorithm. Index Terms--Compensation theorem, interval analysis, soft-switching converters, steady-state analysis.

In this paper, the small signal analysis of the conventional parallel resonant converter (PRC) operating in the continuous conduction mode will be given. This analysis is based on the state-plane approach that has been successfully used to obtain the steady-state response for resonant converters. Applying perturbation directly to the steady-state trajectory, a discrete small signal model for the converter can be derived in terms of the input voltage, switching frequency, and the converter state variables. Furthermore, it can be shown that this method can be applied to resonant converters in general, regardless of the order of their resonant tanks. Based on the derived closed-form solution, frequency responses of two transfer functions will be obtained: input-to-output and control-to-output transfer functions. Finally, computer simulation and experimental results will be reported.