Design and Optimization of IMF Coil Structure to Obtain Strong Misalignment Tolerance and High Transmission Efficiency in Wireless Power Transfer Systems

ABSTRACT In wireless power transfer (WPT) systems, lateral misalignment between coils can lead to substantial fluctuations in transmission efficiency. Although various misalignment‐tolerant coil structures have been proposed, many still face challenges in maintaining high transmission efficiency under displacement conditions. To overcome these limitations, this paper propose a novel interwoven magnetic field (IMF) coil structure that simultaneously achieves strong magnetic coupling and enhanced misalignment tolerance. The proposed IMF structure partitions the transmitting coil into two functional components: a primary transmitting coil configured as a double‐D (DD) coil, and auxiliary compensating coils implemented as bipolar (BP) coils symmetrically placed on both sides of the DD coil. The receiving side employs a reverse‐series connection coil configuration. The IMF structure benefits from the inherently high coupling efficiency of DD coils relative to conventional single coils for the same footprint, while the BP coils provide edge compensation. This configuration enables the system to sustain high efficiency even under coil displacement. Specifically, when lateral misalignment occurs along the direction of vehicle motion, the magnetic interaction between the reverse‐series receiving coil and the edge‐positioned BP coils adaptively compensates for the misalignment, thereby preserving the stability of the system of transmission efficiency. Under a horizontal misalignment along the ‐axis corresponding to 50% of the transmitter coil length (394 mm), the IMF system exhibits a maximum transmission efficiency fluctuation rate of only 0.21%, while achieving a peak efficiency of 97.16%.