Improved Equivalent Circuit Model of HTS Dynamo Based on Integrating a Feature on Frequency Dependency of Critical Current

The charging current and output voltage of the High temperature superconducting (HTS) dynamo flux pumps can be calculated using a simple equivalent circuit model (ECM). Thus, the charging curve prediction would be faster. Creating a model that accurately and quickly simulates HTS Dynamos' operation enables the obtaining of expected results with sufficient accuracy before experimentation and prototyping, thereby improving design, research and development efficiency. Previous studies on ECM-based simulation indicate a growing discrepancy between simulation and experimental results as the operating frequency increases. Yet, no model has addressed this problem. In this paper, a frequency-improved ECM for HTS Dynamo based on the integration of the frequency dependence of critical current into ECM has been proposed and developed in SIMULINK, which directly addresses the aforementioned research gap. The model takes into account the impacts of dynamic resistance, the E-J Power Law, and the frequency dependence of the critical current of the HTS tape on the HTS Dynamo performance. The simulated charging current and output voltage of the HTS Dynamo were investigated by varying the rotor rotation frequency and the air gap between the permanent magnets and the HTS tape. An analysis has been carried out regarding the simulation results from the frequency-improved ECM and the original ECM, compared with the corresponding experimental data under the same operating conditions. Finally, the simulation accuracy of the frequency-improved ECM is compared with that of the ECM without considering the frequency dependence of the critical current under the same operating conditions, yielding a significant improvement, with up to a 96.7% reduction in error.