Analysis of Time Domain Loss Model of the LLC Resonant Converter above Natural Resonant Frequency

This paper presents a modeling method of loss model for LLC series resonant converter (LLC-SRC) operating above the series resonant frequency. Traditional Fundamental Harmonic Approximation (FHA) modeling method only considers the fundamental components of switching frequency, and the model established by FHA method has low precision when the LLC-SRC works far away from the series resonant frequency points. Therefore, this paper adopts the Time Domain Analysis method (TDA) to model LLC-SRC with higher accuracy, and the gain characteristic equation as well as the physical quantities of each component of the converter are also derived to established the loss model, and the theoretical conclusions are finally verified by simulations.