Single-stage Output Converter Based Wireless Power Transfer System And Its Singular Perturbation Modeling And Control

Wireless power transfer(WPT)technology is widely adopted in different applications.It is of vital importance to improve WPT system comprehensive performances,which consider power modulation range,output quality,overall efficiency,and so on.Output converter in the receiving side greatly impacts on the comprehensive performance.Conventional cascaded converter and the commonly-used single-stage converter fail to optimize system performance comprehensively.Therefore,a single-stage output converter is proposed in this paper to improve system comprehensive performance.Moreover,dynamic model is needed to investigate system dynamic characteristics and design closed-loop controller.Precedent dynamic models suffer from the problems of high order or inaccuracy.It is a challenging task to establish an accurate while simple dynamic model.Singular perturbation theory is adopted to develop a simple and accurate dynamic model for high-order WPT system and design closed-loop control based on the derived model.Work of this paper are mainly as follows.Firstly,surrounding the goal of improving WPT system comprehensive performance,a single-stage output converter,combining bridgeless rectifier and Cuk topology,is designed.The impacts of the proposed converter on the system performances are analyzed in detail.Afterwards,WPT system parameters are designed.The proposed converter is proved to perform comprehensively advanced features with the characteristics of a wide power adjusting range,tiny output ripple and relatively high efficiency.Secondly,in terms of time scales separation of the WPT system,dynamic model of the WPT system is developed based on singular perturbation theory.Also,validity of the model is explained and verified by theoretical analyses and simulation.Comparing to other accurate models,the derived model well balances simplicity,integrity and accuracy.Thirdly,closed-loop control for the output converter is designed based on the singular perturbation model to realize constant voltage or constant current for system output.The cascaded PI control structure is adopted,and the control parameters are designed according to the time-scale separation principle to guarantee stability and rapidity of the closed-loop control.This designe method is much simpler than that based on original high-order model.Finally,a WPT system prototype is built to carry out experiments.The modulation effect of the single-stage output converter is tested.The proposed singular perturbation model is furtherly verified.At last,closed-loop control is conducted.Experiment results give firm support to the advantages of the single-stage output onverter and the singular perturbation method.