High-Power-Density Wireless Power Transfer System for Autonomous Underwater Vehicle Based on a Variable Ring-Shaped Magnetic Coupler

The mass of a magnetic coupler increases with the output of its wireless power transfer (WPT) system, limiting broader application of this technology. It is imperative to solve this tradeoff between output power and coupler mass. Here, we present a high-power-density WPT system designed for autonomous underwater vehicles (AUVs) based on a variable ring-shaped magnetic coupler. A lightweight design is achieved through the system topology and magnetic coupler structure, and the system parameters are optimized and analyzed. Our magnetic coupler can eliminate the gap between the AUV and the platform when charging and fix the posture of the AUV to improve the system power output and stabilize the transmission process. An 800-W prototype was built, and the manipulation of the variable ring-shaped magnetic coupler maintained the dc–dc transmission efficiency of the system at 86.4% and increased the output power by 69.47 W or 9.1%. With these improvements, the system power density reached 1.6 W/g after using the variable ring-shaped magnetic coupler, realizing an increase of 9.6%. Experimental results validate the theoretical analysis and simulation outcomes to prove the effectiveness of this new method.