A Simple yet Accurate Discrete Time Series Resonant Converter Model for Transient Operation

The efficiency, size and weight of electrical converters grew in importance during the ongoing electrification over the last decade. Especially when galvanic isolation is required, resonant converters are now among the most often used converters.Many different models can be obtained using the methods of Fundamental Harmonic Approximation, Generalized Averaging Method and Extended Describing Function. The nature of these techniques is such that, when the requirement for accuracy increases, the model becomes more complex due to the higher order this entails.To remedy this shortcoming, the following article presents a second order, discrete time, control-oriented model for CL(L)LC Series Resonant Converters. Due to the model’s simple structure and its applicability below as well as above resonance frequency, it can be used in a wide range of applications including control system transfer function estimation, stability analysis, mode prediction and in advanced control methods such as active damping.