A Strong Misalignment Tolerance and Low Stray Magnetic Fields Wireless Power Transfer System for Planar Type AUV with Hybrid Magnetic Coupler

The influence of multi-dimensional misalignments on the output characteristics and stray magnetic fields interference present critical challenges to the wireless power transfer (WPT) systems for planar-type underwater vehicles. To address the aforementioned issues, this article proposes a dual-channel magnetic coupling mechanism. The newly developed stepped bipolar four-coil (SBF) transmitter structure, integrated by bipolar four-coil units and stepped coils, effectively suppresses the stray magnetic fields while simultaneously generating a uniform magnetic field distribution. Furthermore, a rectangular cross-shaped solenoid pad (RCSP) receiver featuring a structural compatibility is put forward. The complement effect of rectangular and cross-shaped solenoid coils is employed to ensure the pick-up of both vertical and horizontal magnetic flux, thus, a nearly constant mutual inductance between the proposed SBF-RCSP magnetic coupler is achieved. A 500W experimental prototype is constructed to validate the proposed WPT system. Within a lateral misalignment range of 100 mm, full 360° rotational offset, and 15° tilt angle, the output power fluctuation does not exceed 9.06%, and the transmission efficiency variation remains within 0.88%. Stray magnetic field in the evaluation region is reduced by 72.83% compared with that of a rectangular coil with the same self-inductance.