The Power sub-system is responsible for supplying regulated electric energy throughout the satellite. The power subsystem sustains all the other electrical subsystems on board the satellite. Solar energy being the primary source is tapped using advanced space-grade solar cells, and stored in Lithium Ion batteries.
This energy is conditioned efficiently and distributed to the electrical loads of other sub-systems at the required voltages. The batteries are charged in by a charger running a specialized Li-ion battery charging algorithm.
The system incorporates some of the best off-the-shelf DC-DC converters available in the market so as to condition the raw energy from the sun and the batteries to regulated and stable voltages which are fed to the rest of the satellite. Various methods and tweaks in the design are incorporated to extract the best performance possible.
COEP Pico-satellite is equipped with an ingenious load protection mechanism to perform functions similar to a circuit breaker arrangement. This mechanism caters to all the possible faults that may occur in the systems’ functioning and can take regulatory action. This module has been provided triple redundancy to make it foolproof.
Owing to its critical role in the mission success, the power system is simple and robust. A notable feature of the system is its fully Analog, Microprocessor Independent Design to co-ordinate critical functions. Almost all critical decision making tasks are hard-wired by basic feedback from the components. Hence, as small as our system is, we have improved the systems’ stability to single event effects. The power subsystem is completely analog in nature and also fully autonomous in its functioning, being the first subsystem to start up after the launch.
The power system is also entrusted the responsibility of gathering important parametric information like temperature, solar panel current and battery health. The sensors gather these parameters and relay the same to the On-board Computer for data logging.
Work of the power system is also bound by the elaborate “Power budget” that has been carefully crafted. It matches the consumption of each module and validates that the generated energy supports the demands of all the on-board modules.
1. Design of digitally controlled battery charger with Maximum Power Point Tracker (MPPT)
2. Designing motor drivers for deployment
Recently presented two papers titled “Qualification tests and performance validation of power system for small satellites” and “A generic fine-grained energy budget for satellite applications” in the Space Power Symposium at the 66th International Astronautical Congress, Jerusalem, Israel.
The team also completed stress testing for stand-alone Power card as well as in integrated form with OC and Communication sub-systems of Swayam.