A Two-time-scale Modeling Method for WPT Systems Powered by Distributed Energy Sources

When the wireless power transfer (WPT) system is directly powered by the distributed power sources, it can greatly improve the range per charge of the electric vehicles (EVs). However, the conventional modeling methods cannot describe the behavior of the cascaded system accurately because of the different operating frequencies. To overcome this drawback, a two-time-scale modeling method consisting of a fast and slow reference state variable is proposed in this paper by using the two time-scale. Each stage of the system is considered in the model, enabling the high accuracy. Besides, the pseudo-continuous conduction mode zero-voltage-switching (ZVS) modulation strategy is used in the first stage to achieve the high efficiency and voltage step-down/up without changing the operating mode. Simulation results verify the accuracy of the proposed model and theoretical analysis.