A Rotating Wireless Power Transfer Method With Scalable Current Sharing Topology and Spiral Interwoven Q Coils for the Rotary Steerable System

For rotary steerable systems (RSS) used in oil and gas drilling, wireless power transfer (WPT) technology faces challenges such as the excessive number of compensation components, high coil copper loss, and unbalanced branch currents. Under low-voltage and high-current conditions, these issues might degrade system efficiency and reliability. To address these issues, this paper proposes a WPT system based on a scalable current sharing topology and spiral interwoven Q coils. The proposed scalable current sharing topology, which requires no compensation inductor, effectively reduces losses in both the coils and the compensation components. Meanwhile, the magnetic coupler is constructed by spiral interwoven Q coils, featuring high scalability and uniformity of mutual inductance. In addition, a universal parameter design method is introduced to effectively balance the branch currents. Finally, A 478 W prototype with 48 V input and output is built for validation. During the rotation process, the output voltage fluctuation is only 3.84%, and the average efficiency is 90.59%. It has stable and efficient output under both load changes and multi-directional misalignment of the magnetic coupler.