Importance

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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. The motor driver circuit provides the advantages of increased efficiency, operation from a variable power source, tight control of temperature regulation, a fail-safe mode of temperature sensor feedback, and a small envelope space enabling electronic controller mounting internal to the cooler motor/compressor assembly of a linear cryogenic cooler.

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First Claim