A superconducting wireless energiser based on electromechanical energy conversion

A superconducting magnet (SM) can produce high magnetic fields up to a dozen times stronger than those generated by an electromagnet made of normal conductors or a permanent magnet (PM), and thus has attracted increasing research efforts in many domains including medical devices, large scientific equipment, transport, energy storage, power systems, and electric machines. Wireless energisers, e.g., high temperature superconducting (HTS) flux pumps, can eliminate the thermal load from current leads and arc erosion of slip rings, and are thus considered a promising energisation tool for SMs. However, the time-averaged DC output voltage in existing HTS flux pumps is generated by dynamic resistance: the dynamic loss is unavoidable, and the total AC loss will become significant at high frequencies. This study introduces a highly efficient superconducting wireless energizer (SWE) designed specifically for SMs. The SWE takes advantage of the inherent properties of a superconducting loop, including flux conservation and zero DC resistivity. Extensive theoretical analysis, numerical modelling exploiting the H-ϕ formulation, and experimental measurements were conducted to demonstrate the efficiency and efficacy of the novel SWE design. The electromechanical performance and loss characteristics of the SWE system have also been investigated. Compared to conventional HTS flux pumps, the proposed SWE has lower excitation loss, in the order of 10⁻¹ mW, and thus can achieve a high system efficiency of no less than 95%. Furthermore, it has a simpler structure with higher reliability, considered ready for further industrial development. In addition to deepening the understating of the intricate electromechanical dynamics between magnetic dipoles and superconducting circuits, this article provides a novel wireless energisation technique for SMs and opens the way to step changes in future electric transport and energy sectors.