A 1-kW wireless power transfer system for electric vehicle charging with hexagonal flat spiral coil

Abstract

Wireless Power Transfer (WPT) technology is getting more attention in these days as a clean, safe and easy alternative to charging batteries in several power levels. Different coil types and system structures have been proposed in the literature. Hexagonal coils which have a common usage for low power applications, have not been well studied for high and mid power applications such as in Electric Vehicle (EV) battery charging. In order to fill this knowledge gap, the self and mutual inductance equations of a hexagonal coil are obtained and these equations have been used to design a 1 kW WPT system with hexagonal coils for a mid-power stage EV charging. The theoretical and simulation results have been validated with an implementation in the laboratory and a DC-to-DC power efficiency of 85% is achieved across a 10 cm air gap between the perfect aligned coils. The misalignment performance of the system was observed for different positioning of the secondary coil and the output power variation is given. In addition, the effect of shielding on magnetic field exposition of a driver sitting in an EV was obtained and these simulation results were compared in order to check the compliance with international health standards.

Inductive Power Transfer for Electric Vehicle Charging Applications: A Comprehensive Review

“…A 1 kW design with a flat spiral square coil design was proposed for mid-power EV charging [28]. Hexagonal coil was proposed to have a high coupling coefficient, more tolerance to misalignment and effective structure for multi-array coils such as honeycomb designs [29][30][31][32]. A circular coil structure is the most common, but it is particularly sensitive to misalignment.…”

“…An aluminum plate is used as shielding to reduce magnetic field density values in this work. In order to show the effect of aluminum shielding effect on magnetic field density values of a 1 kW WPT system with an operating frequency of 20 kHz and hexagonal coil, the 3D model was created and analyzed on ANSYS Maxwell [30]. The FEA (Finite Element Analyses) results show that the aluminum shielding has a significant effect on reducing the magnetic field density.…”

Literature Review on Wireless Power Transmission by Magnetic Resonance Coupling Method

“…Ayrıca tasarımın uluslararası sağlık standartlarına uygun olması için alıcı bobin üzerine alüminyum tabaka yerleştirilmiş ve bu tabakanın manyetik alan sonuçlarına etkisi simülasyon ile elde edilmiştir. Maksimum manyetik alan yoğunluğu, uluslararası standartlara göre kabul edilebilir bir değer olan 20 μT olarak elde edilmiştir (Aydın & Aydemir, 2021).…”