Loss Reduction and Operating Time Extension Using Segmented HTS Field Coil Bobbin for High-Speed Operation of EV Traction Motor

This study investigated the thermal and electrical characteristics of a high-temperature superconducting motor intended for electric vehicle traction. Particular attention was paid to mitigating the temperature increase induced by eddy currents in the aluminum bobbins and to increasing the operating time while maintaining the critical current margin. Adjustments were made to incorporate multiple axial segments composed of anodized aluminum, thereby establishing segmented eddy current loops. Models ranging from two to 40 segments were investigated at the maximum power of 300 kW for the motor. It was observed that the implementation of a 40-segment bobbin reduced the eddy current losses by approximately 78%. A marked decline in the temperature rise was realized, considerably extending the operational time of the motor. The operational time increased from an initial 7 seconds at maximum power to 221 seconds, attributed to the reduced eddy current losses and the resulting decrease in temperature rise.