Fast Distributed Simulation of 'Defect-Irrelevant' Behaviors of No-Insulation HTS Coil

This paper proposes a new equivalent circuit model to calculate current distribution in an NI (no-insulation) high temperature superconductor (HTS) coil that contains a defect. When the well-known defect irrelevant behaviors of an NI HTS coil are analyzed, the so-called partial element equivalent circuit (PEEC) technique has been commonly adopted. However, the PEEC technique often takes an extremely long time, days or even weeks, for just a single simulation depending on the number of internal elements within the target NI coil. Here we propose an alternative method that may substantially reduce computation time and load in distributed simulation of the defect-irrelevant behaviors of an NI HTS coil. We showed that the current sharing region of an NI coil containing a defect could be divided into 5 segments, and an equivalent circuit, which is named 'B model' as the equivalent circuit resembles the alphabet 'B,' could be constructed using circuit parameters in each segment. Using the proposed method that significantly simplifies the existing PEEC model, we successfully simulated the defect-irrelevant behaviors of an NI HTS single pancake coil, essentially the local current sharing between the defect spot and its healthy neighboring turns.