Optimization of an HTS Induction/Synchronous Motor According to Changing of HTS Tapes Critical Current by Analytical Hierarchy Process

This paper represents the performance of a squirrel-cage High Temperature Superconducting Induction/ Synchronous Motor (HTS-ISM) based on nonlinear electrical equivalent circuit. The structure of the HTS-ISM is the same as that of the squirrel-cage type induction machine, and the secondary windings are fabricated by the use of the HTS wires. It has already been shown that based on the experiments that even this simple replacement realizes the excellent improvement of the performances such as coexistence of slip and synchronous rotations, higher efficiency (due to the synchronous operation), and robustness against the overload. In this paper, the transient modeling of this motor is performed by Matlab Simulink. Also, it is shown by FEM that starting and synchronous torque is extremely dependent on input voltage and critical current of superconducting tapes of the rotor. So, the starting and synchronous torque of the HTS induction motor can be improved with adjustment of the input voltage and critical current of the rotor HTS tapes. Also, in order to optimize both the starting and synchronous torques simultaneously, the relationship between these torques and the critical current of the HTS tapes have been investigated. Finally, according to the variation of the critical current, we optimized the design of the motor by analytical hierarchy process with finding the appropriate critical current for HTS tapes of rotor. The equations obtained are nonlinear, and then the typical Newton–Raphson method is used for the calculation.