An Optimal Design of Contactless Power Transfer System Applied for Electric Vehicles Using Electromagnetic Resonant Coupling

Abstract

Over the past decades, contactless power transfer (CPT) has been acquiring considerable attentions for investigations on wireless power transmitting (WPT) based electric vehicles (EV) charging solutions. This paper describes a geometrically improved CPT system using innovative H-shape ferrite core prototype and electromagnetically analytical methods. In order to address the key issues such as system power transfer rating levels, maximization of system efficiency and charging distance of two coils, the CPT prototype in this paper focuses on operating frequencies, coupling distances and electromagnetic performances. This H-shape CPT prototype has been modelled in 3D finite element method (FEM) environment, resulting in a maximum coil transmitting efficiency of 63%, an optimal system efficiency of over 40% and a maximum RMS real power of 20.39 kW on the load end, with an air gap of 30 mm. Moreover, the H-shape system with 20-mm air gap could be measured to output an RMS real power of 31.95 kW on the load of the CPT system, achieving a maximum coil transmitting efficiency and overall system efficiency of over 77% and 47%, respectively. Furthermore, from the perspective of electromagnetics, the proposed CPT coupling design in this paper tends to appear advantages on electromagnetic field performance by analyzing the generated parameters of flux linkage, flux line distributions, magnetic flux density and so on. In addition, the limitations and future works on the CPT technologies for EV have been discussed in this research paper.