Design, implementation issues and performance of an inductive power transfer system for electric vehicle chargers with series-series compensation

The design, construction and evaluation of a contactless battery charger for electric vehicles (EVs) based on inductive power transfer (IPT) is presented in this study. The design of such systems entails a high degree of complexity because of the large number of design parameters involved and, consequently, trade-offs in selecting the key design parameters have to be established. The design process and selection of the IPT system parameters is detailed in this study, considering the most common specifications of EV chargers and the practical issues of the implementation. Regarding the compensation scheme, which is one of the main issues in the design, series compensation in both the primary and secondary has been adopted because of the advantages identified after a comprehensive analysis. A laboratory prototype has been built and tested, providing extensive results of the system performance in terms of efficiency and power transfer capability, considering load power variations, as well as changes in the air gap between coils. A detailed analysis of the efficiency of each stage in the IPT system and their contribution to the overall efficiency is also provided.