Nonlinear behavior of wireless power transfer systems: modeling, analysis, and experimental verification

Wireless power transfer (WPT) systems typically consist of multiple cascaded power converters with their own operating modes. This paper proposes a cascaded modeling method, which segments the complex structure of the whole system into a number of power converter units (PCUs). For each PCU, a state-space model is constructed with the preceding PCU’s output voltage as its input voltage, and the succeeding PCU’s input impedance as its equivalent load. A regressive algorithm is developed to evaluate the full dynamic responses of the whole system using these PCU models. To illustrate the effectiveness of the proposed cascaded modeling method, a buck converter with a series connected inverter of a two-PCU WPT system is analyzed as an example. Both simulation and experiment results are used to verify the proposed modeling method. The proposed method significantly simplifies the modeling process of cascaded power electronic systems and achieves excellent accuracy for analyzing the nonlinear bifurcation behaviors.