Design and Analysis of a Direct-Drive Motor for Antarctic Astronomical Telescopes in Extreme Environments

Motors are crucial for astronomical telescopes, especially for those operating in Antarctica. The harsh environment and operation conditions in Antarctica, including extreme low temperature, ice/snow accumulation and invasion, low power consumption and unattended operation, introduces a lot of challenges in the design and development of motors used in telescopes. This paper presents the design of a permanent magnet synchronous motor suitable for this environment. A quantitative analysis is conducted on the impacts of cryogenic conditions on lubricant performance, differential thermal contraction of metallic components, and remanent flux density of neodymium iron boron (NdFeB52) permanent magnets. To mitigate ice crystal intrusion risks, a labyrinth seal structure combined with silicone sealing rings is implemented. Finite element analysis and laboratory tests demonstrate a maximum torque output of 25 Nm. This kind of motor is used in the near-infrared telescope with 150 mm aperture at Dome A, Antarctica. Operation data shows a total encoder feedback error of 0.0678" for the telescope control system with 15''/s tracking speed at -56.79°C. These results comprehensively validate the motor's high reliability and precision under polar extreme environmental conditions.