A Miniature Permanent Magnet Motor for Low Capacity Reverse-Brayton Cyle Cryocoolers for Space

This proposal addresses the development of a novel permanent magnet motor for a miniature centrifugal compressor. The compressor is a critical component in a low capacity, vibration free, long life cryocooler. Key features of the development include the incorporation of a permanent magnet in a miniature high speed shaft, and a unique and simple control system to synchronize the motor at its optimum efficiency point. This motor concept promises a major increase in efficiency over existing miniature induction motors. The increase in efficiency will, for the first time, enable the use of turbomachine-based cryocoolers in spaceborne applications where input power to the system is limited to about 100 W and where cooling requirements are in the range of 0.5 W - 2 W at temperatures between 35 K and 100 K. Phase I consists of proof-of-concept demonstration of the permanent magnet motor. In Phase II, prototype compressor will be designed, fabricated, and tested in reverse-Brayton cryocooler.