Abstract: A reciprocating compressor includes an electric motor having fixed and moveable components within a housing for reciprocating a moveable assembly, to compress a working fluid within a variable volume compression chamber within the housing. An integrated flexure spring and circuit connected between the housing and the moveable assembly axially and radially centers the moveable assembly within the housing, and additionally, supplies an electric current to a moveable current coil of the electric motor associated with the moveable assembly. The moveable assembly is axially reciprocated against a restoring force of the integrated flexure spring and circuit responsive to an axial force exerted on the moveable assembly by the electric motor when the electric current is supplied to the moveable current coil via the integrated flexure spring and circuit.

Abstract: A highly efficient motor driver circuit of an electronic controller for linear cryogenic coolers operates directly from a variable power supply, such as a battery, without the need for the voltage regulator control circuit of the prior art. Elimination of the prior art voltage regulator ensures a higher efficiency motor driver circuit of the electronic controller. Both open-loop and closed-loop controllers electronically control the motor driver circuit. The open-loop controller protects against temperature sensor failure, and will limit maximum motor power as a function of system ambient temperature. The closed-loop controller regulates the temperature of the cold finger accurately to a preset value, using feedback from a temperature sensor along with a novel pulse-width modulation concept for modifying motor drive waveforms.