Speaker
Description
In practical high-temperature superconducting (HTS) applications, various harmonics are present, causing the transport current to become non-sinusoidal, which may pose new challenges for controlling AC losses. However, the transport AC loss characteristics of REBCO coated conductor (CC) with magnetic substrates under non-sinusoidal currents are still unclear. In this study, we performed a numerical study of the AC loss of a 4.8 mm wide RABiTS REBCO CC carrying both sinusoidal and non-sinusoidal currents. The current amplitude, frequency, and n-value were varied. The non-sinusoidal current waveforms studied included square waves, trapezoidal waves, and triangular waves. The results show that at low frequencies, the AC loss is predominantly due to the superconducting layer and the magnetic substrate, with the AC loss being highest for the square wave current waveform and lowest for the triangular waveform, as determined by the flux penetration depth. At high frequencies, the eddy current loss in the metal layer dominates, but the AC loss remains highest for the square wave and lowest for the triangular wave, driven by the induced eddy currents. Furthermore, the REBCO CC with a magnetic substrate still follows the critical state model, meaning that for an infinitely large n-value, the differences in AC loss values for all waveforms would disappear.
