  IR (Infra-Red) detectors are widely used in Space-borne remote sensing
satellites. In order to achieve a high signal to noise ratio, the IR detectors
need to be operated at cryogenic temperatures. Traditionally, the cryogenic
cooling of these detectors is achieved using passive cooling techniques.
However recent trend is to employ Stirling-cycle based miniaturized active
cryocoolers. An accurate and stringent control of active cryocooler cold-tip
temperature is essential to accomplish high signal & image quality from the IR
detectors. This paper presents work on investigations and comparison of
performance of proposed 2-DOF (2-Degrees-of-Freedom) versus traditional 1-DOF
feedback-control structures for the control of cryocooler cold-tip temperature
used in IR (Infra-Red) detectors of Space Satellites. Towards this,
first-principle based control oriented mathematical model simulated in
Matlab/Simulink is proposed to support such investigation and controller
tuning. Open-loop (system) and closed-loop (controls) simulation results are
tuned & validated with the experimental data obtained from the Lab-scale
test-setup of a commercial Stirlingcryocooler. The performance of 2-DOF
feedback control structures are analyzed with the help of experiment results
offering a better cold-tip temperature control performance.
