T - formulation based numerical modelling of dynamic loss with a DC background field

High-temperature superconducting (HTS) generators offer the advantages of high efficiencies and increased power densities. Most superconducting generator designs feature DC field windings to provide the required magnetomotive force. The superconducting field windings in HTS machines are subject to complex magnetic fields, which lead to dynamic losses occurring in the winding. This magnetic field environment has a large DC background component due to the self-field of the superconducting field windings. This paper investigates the dynamic loss in combination with a DC background field using a T – formulation based numerical model, where the dynamic region is used to identify the dynamic loss. Our double claw pole generator design, which offers a high power density at low superconducting tape requirements, is used as a case study for dynamic loss analysis with a DC background field. Results show that DC background field has a strong effect on the dynamic loss due to the reduced critical current. In addition it was shown that the T – formulation based numerical model in conjunction with the dynamic region requires further research to accurately predict the dynamic loss due to the changing DC current transport region.