Analysis and Verification of cooling structure of superconducting motors for electrical aircraft propulsion

The hydrogen-powered aviation hybrid technology is one of the important directions of the development of electrical aircraft propulsion. Superconducting motors (SCMs) are the core components of a hydrogen-powered aircraft due to their high power-to-weight ratio. Among SCMs, partial SCMs with superconducting armature windings and permanent magnets (SC-PMMs) are the research front and hotspots. This study focuses on the key issue of cooling the superconducting (SC) coils of SC-PMMs. The advantages and disadvantages of three cooling structures, namely core conduction cooling, coil immersion cooling, and core and coil immersion cooling, are compared. The temperature of the SC coils in different cooling structures is simulated and analyzed in detail. The obtained results show that the temperature of the coils in the core and coil immersion cooling structure is not much different from that in the coil immersion cooling structure, with a temperature difference of about 1.5 K only. However, the implementation of the core and coil immersion cooling structure is much easier. Therefore, an SC-PMM prototype is developed using it as the cooling structure, and the temperature change in the prototype under different operating conditions is investigated experimentally. The obtained results show that the final stable temperature during the cooling process is 76.8 K, and the coil on the top is more likely to quench than that at the bottom. The maximum frequency and maximum current at which the prototype can operate stably for a long time are 200 Hz and 49 A, respectively. This study verifies the effectiveness of the core and coil immersion cooling structure, obtains the quench prone area in SC-PMMs, and lays the foundation for the development of high-performance and highly reliable SCMs.