Research of Cryogenic Permanent Magnet Synchronous Motor for Submerged Liquefied Natural Gas Pump

Cryogenic motors, as one of the key components of submerged liquefied natural gas (LNG) pumps, have gradually attracted the attention of researchers with the vigorous development of LNG industry. In this paper, the design, performance analysis, and experiment of a submerged cryogenic permanent magnet synchronous motor (PMSM) are investigated. Considering the effect of cryogenic temperature on material properties, the cryogenic temperature design method is proposed, and on this basis, an 18.5-kW cryogenic PMSM is designed. Then, the finite-element method is used to analyze the motor performance. The analysis is focused on the comparison of electromagnetic characteristics at two different cryogenic temperatures. A multiphysical field model coupling with electromagnetic, fluid, thermal, and stress is established and simulated, and the analysis results proved the rationality of the design. Finally, a prototype was fabricated and tested, providing measurement results that show a stable operation of the motor, which validated the theoretical design and analysis.