Metamaterial Slabs for Electric Vehicle Wireless Charging Application

Abstract

Design and development of a wireless charging system with metamaterial slabs for electric vehicles (EV) based on the Society of Automotive Engineers (SAE) standard is proposed in this paper. The objective is to study the effect of the metamaterial slab on wireless charging efficiency. The wireless charging system was set with a distance between the coils of 0.15 m and a resonant frequency of 81.64 kHz. The symmetrical metamaterial slab (SM) and the edge metamaterial slab (EM) were designed. The experiment varied the placement position of the metamaterial slab in four cases. The efficiency of the wireless power transfer system without the metamaterial slab (WOM) was the highest at 75.78% with the coils aligned. The position at which the coils are in alignment has the maximum efficiency. The efficiency tends to decrease when the coil is more misalignment. The EM over the receiver coil (EMR) results in a maximum efficiency of 75.87% at a 0.10 m misalignment. The EMR provides an efficiency that is 8.00% higher than the WOM at a misalignment of 0.20 m. The metamaterial slab is important in increasing the efficiency when the misalignment occurs. In addition, the metamaterial slab shields the magnetic fields over the receiver coil. The magnetic field of the WOM had an average value of 0.0216 mT. Therefore, the magnetic fields of the system are within safe exposure levels according to the International Commission for Non-Ionization Radiation Protection (ICNIRP) guidelines which are 0.1 mT for occupational exposure and 0.027 mT for general public exposure, respectively. The placement of metamaterial slabs can significantly impact the efficiency and safety of wireless power transfer systems.

Keywords

• Electric vehicle
• magnetic fields
• metamaterial
• wireless charging
• wireless power transfer