Study of circulating current distributions for HTS windings

In high temperature superconducting windings a slight unbalance of the branch inductances of the windings might result in heavy circulating current because of zero resistance of HTS tapes compared with conventional ones. It is proverbial that the circulating current worsens the distribution of leakage magnetic filed and consequently does harm to the ac loss and critical current in the tapes. In this paper, the influence of the subcircuit electric resistance on the circulating current is studied by the method of combining magnetic field calculation with circuit analysis. Circulating current distributions of pancake windings can be calculated. The analysis shows that the circulating current caused by zero resistance of HTS tapes is huge, and cannot be ignored. If the subcircuit electric resistance increases, circulating current will tend to uniformity. ly, circulating current caused by unbalance of the branch inductances will decrease in the wake of total current unbalance diminution by degrees.