Clearance seal compressors with linear motor drives part I: background and system analysis

Linear compressors with clearance seals and flexure bearings have been used for many years for space applications, and this article describes the development of linear compressors at Oxford. A new design of moving magnet motor is introduced and the use of flexure springs, linear motors, valves and their integration are all discussed. A ring down test indicates that the ‘viscous’ damping in the linear compressor is acceptable (in terms of the decay ratio against the number of periods). The measured motor characteristics compared well with the vector fields electromagnetic finite element model. With a revised structural design it is predicted that the motor efficiency would be 86% for the rated power (200W shaft power at 50 Hz) enabling the linear compressor to have a high overall efficiency. The companion paper covers the experimental evaluation of the linear compressor.