Research On Dynamic Compensated Wireless Power Transfer Systems With Switch Controlled Capacitor

As the wireless charging of electronic devices and electric vehicles gradually go into public's vision and life,wireless power transfer(WPT)attracts more and more attention.Compared with contact power transfer,WPT has advantages of high security,flexibility and convenience.One kind of WPT is inductive wireless power transfer and it is used broadly.Then there are growing expectations for the flexibility of load and coils' relative position in inductive WPT system.However,the change of load or coils' relative position can cause the change of efficiency and system characteristics,which limits the application of WPT a lot.Therefore,solving the contradiction between the flexibility of coils' relative position,load and the system performance has become an urgent problem.To solve the aforementioned problem,based on compensation network design,a switch-controlled capacitor(SCC)based WPT system scheme is proposed in this thesis.Here SCC is formed by switches and capacitor,whose equivalent capacitance is adjustable.In the proposed system,SCC is applied as compensation capacitor,thus its equivalent capacitance can be modulated to realize tuning when coils' relative position varies.Therefore it provides the topology basis for dynamic regulation.A double-loop dynamic compensation control strategy is introduced for the proposed SCC based WPT system scheme,with which constant output voltage and efficiency optimization can be realized in variable parameter condition.Frequency modulated loop is implemented by phase-locked loop(PLL)for the tuning of leakage inductances and series compensation capacitor s.Besides,SCC loop is modulated by PI controller,whose design is assisted by the open loop Bode plot got from frequency sweep simulation.With SCC loop,parallel compensation is also realized.Then efficiency optimization and constant output voltage are achieved.Simulation model is built in PSIM to verify the proposed system.Experiment platform is also constructed for verification.The simulated and experimental results confirm the feasibility of the proposed SCC dynamic compensation based WPT system scheme.