Feedback Control of Superconducting Current Based on Linear-Motor Type Magnetic Flux Pump

The linear-motor type magnetic flux pump serves as a wireless power source intended for charging second-generation (2G) high-temperature superconducting (HTS) double-pancake coils (DPC). This study is grounded in the utilization of magnetic flux pump apparatus, in conjunction with the theoretical framework of macroscopic magnetic coupling effects (MMCE). The real-time manipulation of the direct bias magnetic field and the alternating traveling wave magnetic field of the flux pump is employed to facilitate the precise and stable operation of the HTS DPC with a persistent current mode (PCM). Experimental findings demonstrate that the regulation of both the DC bias magnetic field and the alternating traveling wave magnetic field effectively governs the pumped current in the HTS DPC. Notably, exerting control on the alternating power supply, specifically the alternating traveling wave magnetic field, enables the attainment of even greater precision in current regulation and lower system energy consumption, with the load current accuracy presently achievable up to 1%. Additionally, controlling the AC power supply is expected to save between 30% to 70% of energy compared to controlling the DC power supply. This study provides an alternative solution for the PCM operation of the linear-motor type magnetic flux pump, laying a foundation for achieving higher precision PCM and applications in MRI magnets in the future.