Comparison of two kinds of compensation schemes on inductive power transfer systems for electric vehicle

Inductive power transfer (IPT) system is expected for various applications such as battery charger for electric vehicle. In IPT system, series or parallel compensating capacitors are connected to primary and secondary coils to improve power factor on output of inverter. A characteristics difference appears depending on whether the compensation capacitor is connected in series or parallel. Therefore, it is necessary to select the suitable connection method of compensation capacitor depending on applications. This paper experimentally compared the efficiency characteristics of the following IPT systems: series-parallel (S/P) compensation in which primary and secondary side compensation, respectively and parallel-parallel (P/P) compensation in which both primary and secondary side compensation capacitors are connected in parallel, respectively. As a result, it was understood that the efficiency characteristics between S/P compensation and P/P compensation are different. Specifically, it was understood that the total efficiency of P/P compensation is higher than that of S/P compensation when the misalignment of coils is large. Therefore, P/P compensation is suitable for EV.