Presentation Information
[WBP2-05]Technology for trapping strong magnetic fields in HTS bulk by a single pulse magnetic field
*Tetsuya Ida1, Mitsuru Izumi1,2 (1. Tokyo University of Marine Science and Technology (Japan), 2. National Institute of Technology, Toba College (Japan))
Keywords:
Pulse field magnetization,Bulk,WCPM,Flux jump
The superconducting synchronous rotating machines exhibit high torque at low speeds, making them suitable for gearless ship propulsion and wind turbines. Because they have multiple field poles, we want to efficiently magnetize the high-temperature superconducting (HTS) bulk material by pulsed field magnetization (PFM) [1]. However, as is well known, a single pulse magnetic field traps low magnetic field in a HTS bulk material. Until now, many researchers have applied the magnetic fields for multiple times to achieve trapped strong magnetic field. Although this method takes time to magnetize several bulk materials and may cause distortion in the structure of the rotating machine during magnetization, it’s impractical. Recently, active control of power through advances in power electronics freely shapes the pulsed magnetic field waveform generated by the magnetizing coil with low loss. So-called waveform-controlled pulse magnetization (WCPM) controls the generation of flux jumps by applying a pulse field waveform with a shape different from the conventional LCR transient to the HTS bulk, thereby improving the trapped magnetic field properties [1]. In particular, the WCPM using negative feedback control (NFB-WCPM) by using the magnetic flux density measured at the surface of HTS materials as input, trapped magnetic flux density of approximately 4 T was achieved in ø45 GdBCO bulk materials cooled to 40 K [2]. The NFB-WCPM enables strong field trapping by actively controlling the flux jump caused by the transient behavior of magnetic flux within HTS material. Therefore, based on the experimental results, it is expected that a single pulse magnetic field will trap 5 T in the bulk at 30 K. In this presentation, we will show the results of recent magnetization experiments.