An Antirotation Wireless Power Transfer System With a Flexible Magnetic Coupler for Autonomous Underwater Vehicles

Combining wireless power transfer (WPT) technology with an underwater inclusive charging platform is an effective method to solve the problem of energy replenishment for autonomous underwater vehicles (AUVs). To ensure a stable charging state of the AUV at arbitrary positions, an antirotation flexible magnetic coupler (FMC) is proposed in this article. The transmitter structure can follow the retractable cage changes of the charging platform. Through the optimization analysis, the FMC, composed of a single-layer transmitter coil and a double-layer receiver coil and rotated 45° between the two layers of receiver coils, has excellent antirotation capability under 360° rotations. Moreover, the magnetic field of the FMC is evenly distributed and concentrated between the magnetic cores of the transmitter and receiver, causing little effect on the equipment inside the AUV. To address the coupling parameter variations due to AUV rotation and the transmitter contraction during FMC operation, soft switching of the WPT system is achieved by pulse density modulation and slight detuning of the resonator. An experimental prototype was established to verify the antirotation characteristics of the FMC as well as the soft-switching attributes of the system, and the experimental results matched well with the simulations.