Comparison of study on circulating current for different HTS transformer windings

In a HTS transformer a slight unbalance of the branch inductances of the windings might result in heavy circulating current because of zero resistance of HTS tapes. It is well-known that the circulating current worsens the distribution of leakage magnetic field and consequently does harm to the ac loss and critical current in the tapes. In this paper, the influence of the secondary winding configurations on the circulating current is studied by combining magnetic field calculation and circuit analysis, and some suggestions for improving the distribution of circulating current are also presented to make HTS transformers more efficient.