High-temperature superconducting (HTS) coil wounds without turn-to-turn insulation (NI coils) present excellent electrical and thermal performance compared to HTS coil wounds with Kapton tape (INS coils). However, NI HTS coils are physically connected to power supplies at room temperature, resulting in increased operating costs due to complex cooling systems and constant heat loads. To overcome this issue, recent studies have investigated alternative charging methods such as flux pump, a power source without any physical contact with the HTS coil at cryogenic temperatures. Even though the NI coil is charged using a flux pump, the disadvantageously slow charge and discharge time remain. In this study, we conducted experiments to compare the charging characteristics of INS and NI coils using a rotary HTS flux pump. A superconducting circuit comprising two coils with equal inductance magnitude is connected in series. From the experiments, we compare the charging characteristics of charging time constant and magnetic field when the same current is applied to the two coils with a power supply and a rotary HTS flux pump. In the NI coil rotary HTS flux pump case, the charging time constant converged to about 6 s in the alternating magnetic field (AMF) above 20 Hz, and the value is similar to the power supply. At 60 Hz and higher AMF, the maximum magnetic field difference from the power supply converged to less than 1%, which appears to be a difference in current and voltage source.
Bibliographical noteFunding Information:
Manuscript received September 20, 2019; accepted April 20, 2020. Date of publication April 27, 2020; date of current version May 12, 2020. This work was supported in part by the National Research Foundation of Korea (NRF) grant funded by the Korea government (MSIP), and in part by "Human Resources Program in Energy Technology" of the Korea Institute of Energy Technology Evaluation, and Planning (KETEP), granted financial resource from the Ministry of Trade, Industry & Energy, Republic of Korea under grants 2019R1A2C1004715 and 20184030202270. (Corresponding author: Yong Soo Yoon.) Seunghak Han, Haeryong Jeon, and Tae Kuk Ko are with the School of Electrical and Electronic Engineering, Yonsei University, Seoul 30722, South Korea.
All Science Journal Classification (ASJC) codes
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics
- Electrical and Electronic Engineering