A new vision of short-time and long-time AC loss measurement and modelling: A superconducting power electronic circuit. (September 2021)

• Record Type: Journal Article
• Authors: Chen, Xiaoyuan; Chen, Yu; Gou, Huayu; Jiang, Shan; Zhang, Mingshun; Shen, Boyang
• Is Part Of: Cryogenics. Volume 118(2021)
• Publication Date: 2021-09
• Subjects: High-temperature superconductor (HTS) -- HTS coil -- AC loss -- Time/temperature dependence -- Power electronic circuit; Low temperature engineering -- Periodicals; Low temperature research -- Periodicals; 536.56
• DOI: 10.1016/j.cryogenics.2021.103348
• Languages: English
• ISSNs: 0011-2275

Abstract

Highlights: A new vision of loss measurement and modelling for superconducting coils for high-frequency operations. The temperature and time dependence of AC loss in the HTS coil in a power electronic circuit. Both the short-time and long-time loss tests for the HTS coil by a commercial power analyzer. A new time-dependent analytical model for accurately modelling the real-time loss in the HTS coil. Prediction of the real-time performance for numerous HTS devices during practical AC operations. Abstract: This paper provides a new vision of loss measurement and modelling for superconducting coils, with both the short-time test and long-time test, as the behaviour of the AC loss in superconductors is actually a dynamic process with the temperature and time dependence, particularly for the medium-to-high frequency AC operation. A single-pancake High temperature superconducting (HTS) coil was tested in a power electronic circuit (DC-AC inverter). The operating current was from 15 A to 50 A, and the operating frequency was from 1 kHz to 5 kHz. The AC loss measurements were carried out using the function of fully decoupling power by a commercial power analyzer. This method was able to measure the real-time AC loss, and the loss measuring process is much easier than the conventional electrical and magnetic method. As expected, for short-time loss tests, the experiment, the FEM H -formulation model, and the conventional analytical model agree with each other. However, the AC losses in long-time tests are found having power-law relations with the operating time (above kHz level). As the accumulated heat in the HTS coil as well as the interrelation between the critical current and temperature, the real-time AC losses are strongly time-dependent. A new time-dependent analytical model is developed, for the purpose of accurately modelling the real-time loss in the HTS coil. The new analytical model well matches the AC loss tests over both the long and short testing time. The experimental method and new analytical model offer a new sight at the AC loss of superconducting coil for both the short-time and long-time operation in a power electronic circuit, which is able to explore more reasonable guidelines of safe operating area (SOA) during the practical AC operation of superconducting applications.