Performance Study of Cold and Warm Rotor in Superconducting Machine

Superconducting machines can be classified into cold-rotor and warm-rotor topologies based on the rotor's cooling structure. The distributed modular cryostat design gives the warm-rotor topology a novel electromagnetic structure. This paper investigates and compares the electromagnetic performance of both topologies. A 5 MW high-temperature superconducting (HTS) machine is used as the subject of study, with designs for both topologies analyzed. The electromagnetic performance of the optimized designs is then compared. The results indicate that the cold-rotor topology offers superior advantages in weight and volume, while the warm-rotor topology achieves higher efficiency, lower cost, reduced torque ripple, lower AC losses in the superconducting magnets, and thermal load of the low-temperature system. Overall, the analysis suggests that the warm-rotor topology has greater commercial potential.