Abstract Body

REBCO coated conductors will be exposed to rotating magnetic fields in various high-temperature superconducting (HTS) applications,such as HTS rotating machines and flux pumps.  AC loss will be generated in the conductors when they carry AC current under rotating magnetic fields. We define AC loss in the coated conductors with and without AC current as total AC loss and magnetization loss, respectively. Up to now, most of AC loss research has focused on AC loss when the coated conductors are exposed to AC standing magnetic fields [1-5].

In this work, magnetization loss and total AC loss in REBCO stacks comprised of with different number of coated conductors under rotating magnetic fields and AC standing magnetic fields are numerically investigated. We employ 2D finite element method (FEM) based on the T-A formulation. The measured asymmetric temperature-, field- and field-angle-dependent critical current data are applied to each case through the interpolation method. In the simulations, the magnetic field amplitudes are up to 500 mT and the reduced AC current (I_t / I_c0) varies from 0.1 to 0.9, where the I_t and I_c0represent the amplitude of the transport current and self-field critical current of the conductor, respectively. The simulation results are then compared with each other as well as some analytical values.

References

[1] Ashworth, S.P. and M. Suenaga, Measurement of ac losses in superconductors due to ac transport currents in applied ac magnetic fields. Physica C, 1999. 313(3-4): p. 175-187.
[2] Ogawa, J., et al., AC losses in YBCO coated conductors carrying AC transport currents in perpendicular AC external magnetic field. IEEE Transactions on Appiled Superconductivity, 2003. 13(2): p. 1735-1738.
[3] Amemiya, N., et al., Total AC loss of YBCO coated conductor carrying AC transport current in AC transverse magnetic field with various orientations. Superconductor Science and Technology, 2004. 17(8): p. 983-988.
[4] Jiang, Z. and N. Amemiya, An experimental method for total AC loss measurement of high Tc superconductors. Superconductor Science and Technology, 2004. 17(3): p. 371-379.
[5] Grilli, F., et al., Computation of Losses in HTS Under the Action of Varying Magnetic Fields and Currents. IEEE Transactions on Applied Superconductivity, 2014. 24(1): p. 78-110.

Acknowledgment

This work was in part supported by the New Zealand Ministry of Business, Innovation and Employment under the Advanced Energy Technology Platform program “High power electric motors for large scale transport” contract number RTVU2004 and in part supported by the Air Force Office of Scientific Research under award number FA2386-22-1-4054. Yuan Wang acknowledges financial supports from the Chinese Scholarship Council (CSC) and the CSC/Victoria University of Wellington Scholarship.