Non-contact energy transfer system is one of the key technologies of the future electric vehicle charging system.Due to its low coupling coefficient compared to usual transformers, much effort must be applied to improve its efficiency.Especially, series or parallel resonant capacitors are usually applied to improve its rating utilization of the transformer. However,for electric vehicle applications, the relative position between primary and secondary coils can change; therefore, transformer parameters also can change. For that case, the fixed resonant capacitor cannot achieve the maximum efficiency. This paper proposes an active series compensator named MERS applied to the non-contact energy transfer system. The MERS works as aseries variable capacitor in an ac circuit; therefore, can achieve the maximum efficiency of the transformer by optimal equivalent capacitor. A control principle to achieve the optimal operation of the system is described. Experimental results with 1 kW model confirm the operation principle of the proposed method and can achieve a high efficiency off the transformer.
