A Wireless Power Transfer System With High Misalignment Tolerance and Low Component Count

To improve the misalignment tolerance of wireless power transfer (WPT) systems, two or more transmitting coils are generally required with independent control. The independent control of multiple coils usually needs the multiple inverters or additional switches, which increases the size and component count of the WPT system. In this article, a WPT system with novel TX coil driving circuit is proposed for high misalignment tolerance and low component count. The proposed circuit allows a single inverter with only two switches to control the magnetic field of two TX coils independently, which helps achieve the low component count and compact size. In the propose WPT system, two decoupling square coils are adopted as the bipolar transmitter and each of the coil is driven by one switch. When the receiving coil is misaligned, the two coils of the transmitter can distribute the output power according to the different positions of the receiving coil by the proposed driving circuit, thus ensuring a fixed total output voltage, namely high misalignment tolerance. Moreover, the detailed theoretical analysis and design approach are given in this article and the proposed circuit is compared with the existing approaches. A 1 MHz WPT prototype is built for verification purpose, and the constant output voltage can be achieved within a coil misalignment of −6 to 10 cm.