LC/CL compensation topology and efficiency-based optimisation method for wireless power transfer

Wireless power transfer (WPT) has attracted a large amount of attention due to its inherent advantages such as convenience, safety, low maintenance, weather proof and so on. Compensation topology is crucial for WPT system due to its function of reducing reactive power and improving system efficiency. Series-series (SS) compensation topology is widely employed due to a simple structure and the characteristic of constant current output (CCO). However, it has three serious drawbacks: high-voltage stresses on compensation capacitors, poor CCO characteristic under practical situations and significant dependence on coupling coils. This study proposes LC/CL (primary inductor-capacitor and secondary capacitor-inductor) compensation topology to eliminate aforementioned deficiencies of SS. The voltage stresses on compensation capacitors of LC/CL are much lower than those of SS. LC/CL also provides better CCO characteristics in imperfect scenarios. Load current of LC/CL compensated system only increases by 1.89% when the load is reduced by half. In contrast, the load current of SS compensated system increases by 6.87% with identical load reduction. An efficiency-based optimisation method is proposed for higher end-to-end efficiency as well. The validity of the optimisation is justified by both simulation and experiment. The efficiency of the optimised system is about 2% higher than that of a non-optimised system.