Average modeling and simulation of series-parallel resonant converters by SPICE compatible behavioral dependent sources

A new methodology for developing average models of resonant converters is presented and verified against cycle by cycle simulation. The proposed modeling approach applies the concept of R_ac(t) which represent the instantaneous effective load of the resonant network. Unlike the treatment given in previous studies, the value of R_ac is evaluated here dynamically as a function of the temporal low-frequency-average of other relevant variables. Once defined, the model can be used as is to run steady state (DC), large signal (transient) and small signal (AC) simulations on any modern circuit simulators. The proposed methodology was used to develop a behavioral model of a series-parallel resonant converter. Excellent agreement was found between simulation by the proposed model and cycle by cycle simulation.