Extrapolation of HTS Induction Machine Performance From No-Load and Locked-Rotor Ambient Tests Using Hybrid Models

This work proposes a methodology to predict the performance of a superconducting induction motor, with a High Temperature Superconducting (HTS) rotor cage, from its conventional non-superconducting ambient temperature characteristics. This methodology avoids using computationally expensive time-dependent Finite Element Simulations to extrapolate the HTS machine performance. First, the equivalent circuit parameters of the conventional non-superconducting machine are estimated from experimental or simulated no-load and locked-rotor results. Then, these parameters are adjusted for cryogenic conditions and converted to an HTS rotor cage induction machine using a static Finite Element Method (FEM) to capture non-superconducting phenomena, and an analytical model to include the influence of HTS tapes. The methodology is validated experimentally for ambient and cryogenic conditions. Results show that the accurate estimation of the machine torque-speed curve highly depends on the rotor leakage inductance and on the HTS tapes' perpendicular magnetic field. To capture the correct start-up behaviour of the machine, it is required to include the estimation of the tapes' resistive losses and the presence of all HTS tapes' conductive layers. The method can be applied in the early stages of SC-IM development for performance estimation or even preliminary optimization.