Dual Loop Reactive Shield Application of Wireless Power Transfer System for Leakage Magnetic Field Reduction and Efficiency Enhancement

Seungyoung Ahn,Jedok Kim

doi:10.1109/access.2021.3106336

Seungyoung Ahn, Jedok Kim

Open Access

https://doi.org/10.1109/access.2021.3106336

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Abstract

The wireless power transfer (WPT) system generates a high density leakage electromagnetic field (EMF) during its operation. Exposure to leakage EMF has adverse effects on human health. In order to reduce the leakage EMF, a shielding method can be applied to the WPT system. The shielding methods in previous studies reduced leakage EMF, but the power transfer efficiency (PTE) of the WPT system was decreased. Therefore, a shielding method providing high shielding effectiveness (SE) without PTE degradation is necessary. This paper proposes a dual loop reactive shield application for reducing leakage EMF with PTE enhancement. The proposed dual loop reactive shield generates in phase and out of phase magnetic fields simultaneously. The out of phase magnetic field depresses leakage EMF, and the in phase magnetic field increases the PTE. The proposed method is verified for the cases of symmetric and asymmetric WPT systems, including misalignment conditions. The experimental results of the symmetric WPT system showed a 2.1% PTE increase with 55.5% SE in an alignment condition, and a 3.9% PTE increase with 53% SE in a misalignment condition. In addition, the experimental results of the asymmetric WPT system presented a 1.6% PTE increase with 61.3% SE in an alignment condition, and a 2.7% PTE increase with 54.1% SE in a misalignment condition.

Highlights

Since a wireless power transfer (WPT) system providing mid-range power transmission was introduced [1], applications of the WPT system have been drawing attention
This paper proposes a new reactive shielding method having shielding effectiveness (SE) with increased power transfer efficiency (PTE)
2) EXPERIMENTAL RESULTS Figure 18 shows the simulation and experimental results of the transferred power to load for the symmetric WPT system in the alignment condition

Summary

Introduction

Since a WPT system providing mid-range power transmission was introduced [1], applications of the WPT system have been drawing attention. Consumer electronics such as smartphones and smartwatches can be classified as low power WPT applications [2,3]. Home appliances such as televisions and unmanned aerial vehicles (UAVs) can be classified as intermediate power WPT applications. WPT applications to UAVs are gradually increasing with the proliferation of UAV applications [4,5,6]. The WPT system transmits electrical power through a magnetic field, and a high density magnetic field is generated during the operation. A leakage electromagnetic field (EMF) is radiated around the WPT system, and this leakage EMF has adverse effects on human health

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Conclusion