Proposing a new rotating frame-based method for dynamic modelling of resonant converters

Abstract

Resonant converters are widely used in various industrial applications due to features such as wide input voltage range, high efficiency, and high-power density. Mathematical modelling of these converters is crucial because they simultaneously exhibit AC and DC modes, complicating the design of their controllers. This paper proposes a new method for modelling of resonant converters based on the rotating frame theory. The proposed model possesses two essential features for controller design: being dynamic and having all DC states. The complexity of the model is significantly lower than other methods, such as MHA methods. Also compared to first harmonic approximation, Dp and generalized state space averaging methods, the proposed dq model has not any approximations for the inverter output voltage and transferred output voltage in the transformer primary side. The proposed method is compared with conventional modelling methods for such converters, including the first harmonic approximation, generalized state space averaging, nonlinear equation models, and circuit simulation models. According to the presented results, the proposed model demonstrates superiority in terms of accuracy and simplicity over the methods. Simulation results along with practical results from a prototype circuit are provided, highlighting the effectiveness of the proposed method.