AC loss calculation in self-field of NI-HTS coil carrying different transport currents

To solve the problems of the AC loss in self-field for no-insulation (NI) HTS coils carrying different currents, such as AC transport current, the current scanning inverse in order to decrease the screening current, and so on, by using the T-Ahomogenization model based on the E-J power law, the effects of the transport current, frequency, and the n-value on the magnetic flux density and AC loss of NI-HTS pancack coils were simulated. The instantaneous AC losses of square wave, sawtooth wave, and sinusoidal wave for double-pancake coil were simulated quantitatively. The effects of charging and discharging ramping rates on the current distribution were also discussed by using partial element equivalent circuit (PEEC). The results show that the AC losses increase with the increase of frequency from several hundred to kilo Hz. Due to the transfer of the radial current within coil’s turns, some inverse azimuthal currents may appear in the NI-HTS coil in the early charging period, and some of the azimuthal currents may increase during short discharging period for the same reason. The simulation work can provide some theoretical references for the studies of the stability and AC loss for NI-HTS pancake coils.