A step-superposition based analysis approach to modeling resonant converters

This paper introduces a new analysis approach to modeling resonant converters that can be used to determine closed-form expressions for the exact resonant network waveforms. This approach, based on superposition of step responses to inverter and rectifier imposed steps, does not require analysis of the different operating modes of a resonant converter, and can easily be applied to resonant converters with high-order resonant networks, multiple inverters and/or rectifiers. The usefulness of the proposed analysis approach is demonstrated by applying it to a series resonant converter and the recently-proposed impedance control network (ICN) resonant converter. The modeling results are validated using a 200 W, 500 kHz ICN resonant converter. It is shown that there is an excellent agreement between the experimental and modeled waveforms during steady-state operation and during startup.