Review of inductive power transfer technology for electric and plug-in hybrid electric vehicles

For the last two decades, significant improvements in charging technologies have been made. Moreover, novel applications have been proposed and tested, obtaining important and promising results. Inductive charging for electric vehicles (EV) and hybrid electric vehicles (HEV) is one of them. Because of the positive impact that this technology represents, it is important to understand the general characteristics of this novel application. This paper aims to give a general understanding of inductive charging systems for EV and plug-in HEV. The explanation of what is an inductive power transfer (IPT) transformer and how electrical power is transferred through air is also presented. The review of the electrical characteristics of an IPT transformer is shown: derivation of equations and presentation of the equivalent circuit. The analysis of the series-series (SS) compensation topology is covered. Additionally, to validate the theoretical concepts, an IPT transformer setup with a 5cm air gap is simulated. The simulation results where as expected from the theory. The power transfer capability of the system was increased from 0.05 W, with no capacitive compensation, to 87.6 W, with capacitive compensation. The plots and circuit simulations where obtained in MATLAB and SIMULINK respectively.