Subramanya
Thermal Systems Group, U R Rao Satellite Centre, Bangalore 560017
Goutam Tanneru
Thermal Systems Group, U R Rao Satellite Centre, Bangalore 560017
Spacecraft thermal testing involves characterizing the
performance of the constituent sub-systems as well as
integrated satellite at their respective specified acceptance
temperature levels. The acceptance level temperatures of the
subsystems differ from one subsystem to other within a
spacecraft. During the test, the subsystems are maintained at
those temperature levels specified by a pre-defined
temperature profile using skin bonded heaters and IR lamps.
The heaters and IR lamps can be operated using open loop or
closed loop control with temperature set point. As the number
of heaters to be controlled using open loop increases, it
becomes increasingly difficult to maintain the temperatures of
the subsystems at their acceptance temperature limits. Closed
loop PID control is one of the simplest and reliable means of
maintaining the temperature in the dynamic thermal
environment inside spacecraft. The paper describes and
establishes the closed loop control parameters for IR lamps,
skin bonded heaters mounted on low and high thermal inertia
systems using Ziegler − Nichols method as the basis. The
performance of the controller is evaluated using tuned
parameters.