Cooling Design of Oil-Cooling Air-Core Stator for a High-Temperature Superconducting Motor

Temperature rise determines the lifetime of the motor. Wuhan Institute of Marine Electric Propulsion has conceptualized and designed a 20 MW high-temperature superconducting motor (HTSM) with an oil-cooling air-core stator and a superconducting rotor. This paper describes the design and analysis process of the cooling system of this stator: Firstly, We simplified the full structure of the HTSM and established the model of the oil-cooling air-core stator for thermal analysis. Second, We analyzed and compared the cooling effect of different oil inlet forms under different thermal loads and coolant flow, and sequentially determined the optimized inlet form. The analysis results show that the average and maximum temperature of the oil and coil increase with a higher thermal load, or a smaller oil flow. Underrated operating conditions (240 kW@60 m3/h), the maximum temperature of the coil is 72 °C, and the maximum temperature of the cooling oil is 65 °C, meeting the temperature rise requirement. Finally, we present a structural solution for a compact oil-cooled air-core stator that can increase the torque density of the HTSM.