A Rotary Wireless Power Transfer Topology with Constant Voltage Output for Oil and Gas Well

Among the power supply methods of deep down-hole equipment, wireless power transfer (WPT) technology has unique advantages compared with traditional power transfer methods. For rotating drilling equipment, it is necessary to overcome the changes in system performance caused by coil offset. At the same time, a constant voltage (CV) output under a wide temperature range is realized to ensure the safety of electrical equipment in a complex deep down-hole environment. Based on the multilayer disc coil structure, this paper presents a hybrid topological structure with high anti-offset performance. It proposes an impedance network matching method to achieve a CC output independent of the load, which not only avoids complex communication, but also prevents the intervention of complex control means. The effectiveness of the proposed design method is verified by simulation and experiment. It shows that when the coil is axially offset by 200% from the initial position, the voltage change rate is not higher than 7.4%, which is less than the preset value (10%), and basically remains unchanged. On this basis, the overall efficiency of the wireless charging system is not less than 94.8%, realizing high-efficiency power transmission in deep down-hole.