Triple-Coil-Structure-Based Coil Positioning System for Wireless EV Charger

In this article, a triple-coil-based coil positioning approach is proposed for the wireless electric vehicle charger to realize the accurate coil positioning with low electromagnetic field. Based on the working principle of the proposed triple-coil architecture and the discussion of the sensing-coil configuration, the received signal strength (RSS) equations are derived, revealing the way of enhancing the positioning signals by taking advantage of the quality factor (
Q_M
). Thereafter, an RSS fingerprint positioning algorithm is proposed for obtaining coordinates in
x
-,
y
-, and
z
-direction. Specific considerations are also given for designing the exciting frequency and the coil parameters. Finally, the proposed positioning system is tested on a 3.3-kW wireless charger. The RSS of the proposed positioning system has been proved to be 3.2 times as that of the state-of-the-art one, whereas the excitation current is reduced by more than half. A number of positioning cases, with the targeted coil placed in an area of 32 cm × 32 cm, are tested in the lab. The experimental results show that more than 95% of these test cases have been well positioned with test errors less than 1.5 cm.