Wireless power transfer for electric vehicles: Comparative analysis of inductive and resonant coupling with misalignment effects

Abstract

Wireless Power Transfer (WPT) has emerged as a promising charging technology for electric vehicles (EVs), offering enhanced user convenience, improved safety, and reduced mechanical wear compared with conventional plug-in charging systems. Among short-range WPT technologies, inductive power transfer (IPT) and resonant inductive power transfer (RIPT) are currently the most mature and widely investigated approaches. This paper presents a comparative theoretical and numerical analysis of both techniques with particular emphasis on power transfer efficiency and sensitivity to coil misalignment. Equivalent circuit models are developed for non-resonant and resonant topologies using Kirchhoffs voltage laws under sinusoidal steady-state conditions. Closed-form efficiency expressions are derived and analysed. The obtained results show that conventional inductive transfer exhibits a practical efficiency limitation under weak coupling conditions. In contrast, resonant compensation significantly enhances power transfer capability and may theoretically approach unity efficiency under ideal operating conditions. Furthermore, the influence of lateral and angular coil misalignment is investigated through its impact on mutual inductance and coupling coefficient. The study confirms that resonant topologies provide superior robustness against positioning errors, making them highly suitable for next-generation EV wireless charging infrastructure.