A general method for modelling DC/DC and DC/AC resonant converters in steady-state

A generalized approach for the steady-state analysis of DC/DC and DC/AC resonant converters is presented. The analysis can be used for topologies with voltage or current source at the input. Different modulation techniques can be considered: variable switching frequency modulation and duty-ratio modulation. All topologies with 2 and 3 resonant elements, as well as many others up to 12 resonant elements are covered. The model is equally valid for explicit high order resonant tanks as well as high order resonant tanks because of parasitics. Generalized Π and T networks and first harmonic approximation are used. A number of operating characteristics can be systematically obtained: steady-state transfer function, peak currents and voltages of the converter and the tank, peak reactive energy stored in the resonant tank, efficiency, etc. In order to verify the method, a DC/DC LCC current source resonant converter has been built and measured