Project Description:
Using an improved version of the existing Hybrid Heater Controller (HHC) as the fundamental building block (see figure 4 & 5), provide design, analysis and test a prototype of a scalable, single master/multiple slave Thermal Heater Controller System that can be arrayed in a distributed fashion with centralized control by encoding/decoding modulated signals via the power lines (see figure 1, 2 & 3). Improvements in modern electronics and packaging suggest an on-orbit programmable, higher performance system could reduce overall weight and power consumption (15-30%).
Satellite Thermal Management Enhancement Background:
Future satellite imaging systems are moving towards lightweight, scalable, modular, power efficient thermal control systems that thermally stabilize/enable critical optical subsystems. Precious Satellite resources, such as power, need to be configurable on-orbit to provide enhancements in operational mission effectiveness. Design improvements that enhance spacecraft robustness are of considerable value. Example areas of interest include, but are not limited to the following:
· Ability to individually adjust thermal set points on-orbit
· Ability to verify thermal model by system testing prior to launch
· Designs that are lighter weight, more power efficient, and more reliable
· Cost effective increases in subsystem redundancy
· No significant change to EMI/EMC.
ITT would like to demonstrate an enhancement of their current distributed, autonomous thermal control system. The current Heritage system can be described as a group of distributed, autonomous thermal control units that share the same power input. When bus power is present, each controller creates an analog voltage error from a resistance bridge (one element is a thermister that measures the actual temperature), and applying a bang-band control-law with dead-band hysteresis, appropriately supplies energy to a thermal heater to control temperature within ±0.3 °C from a fixed thermal set point.
Using Texas Instrument DSPs (28x family), design, build and test a single master with 4 slaves connected to a single +28v power bus shown in figure 1 below (each slave interfaces to a single heater controller and has its own unique ID). Modify the HHC design as required to provide “the hooks” for local/remote telemetry/control via the slave.
Figure1, System Interconnect Block diagram
Demonstrate:
1. Power-up a HHC in local control mode.
2. Wake/Sleep any individual slave in a network
3. Determine the unique ID of all powered, awakened slaves
4. Obtain thermal telemetry of any unit
5. Command new set temperature to any unit
Team composition:
2 Electrical, 1 Mechanical
Resources:
1. Facilities for developing packaging for slave boxes.
2. Facilities for developing/testing TI DSP and printed circuit boards.
3. Facilities for Vibrational testing of unit
4. Facilities for Thermal testing of the unit
Figure1, System Interconnect Block diagram
Figure2, Master Block diagram
Figure3, Slave Block diagram
Figure4, Hybrid Heater Controller Circuit diagram
Figure5, Hybrid Heater Controller Mechanical diagram