Magnetostatic analysis of a linear motor compressor for micro cryocooler

Abstract Pulse tube cryocoolers are preferred for cooling space satellites, night vision cameras, infrared surveillance systems, because of the absence of moving parts in their cold end. In this paper, a rigorous numerical simulation has been conducted to investigate the magnetostatic characteristic of a moving coil linear motor compressor. Influences of both axial and radial configurations of magnetic circuits on the magnetostatic performance have been analyzed. The distribution of flux density vector and flux density streamlines of both axial and radial configurations have been studied. Finally, response surface methodology algorithms have been utilized to determine the synchronous effects of geometrical parameters on the average magnetic flux density of both radial and axial configurations. It is seen that at a minimum value of width and thickness of the air gap, the maximum value of magnetic field intensity is achieved. Also, at maximum values of width and outer radius of the permanent magnet, magnetic field intensity attains its maximum value. Single objective particle swarm optimization algorithm has been used to optimize the selected geometrical parameters so as to maximize the magnetic flux density of both axial and radial configuration moving coil linear motor compressor. Sobel’s global sensitivity approach has been adopted to determine the local and global sensitivity index of each parameter that has the capability of altering the overall performance. The sensitivity analysis suggests that the radius of the magnet is the most sensitive geometrical parameter.