Electrical Power Systems
The Electrical Power Systems [EPS] team is responsible for the generation, storage and distribution of electrical power on-board the satellite. To cut costs and leverage industry experience, an attempt is being made to ensure as many components in our design as possible are available off-the-shelf.
The satellite EPS can be divided into two sections: power generation and storage, and power
distribution. This division occurs in order to conform to competition guidelines as laid down by the Canadian Satellite Design Challenge [CSDC]. The guidelines state that during launch, all components in the satellite must be disconnected from any power source. In addition, due to the fact that the satellite will be physically inaccessible for maintenance for the duration of its mission, both circuits will be designed to eliminate all single points of failure.
Power Generation and Storage
In order to mitigate the possibility of the satellite losing power while tumbling (e.g. directly after being released into space before its orbit has been established), solar cells are to be placed on all six faces of the satellite. This configuration will help to ensure that, while the satellite is on the sun-facing side of the earth, some amount of electricity will always be being generated. The difficulty with this design is that, during normal operational modes, sunlight will be hitting the different sides of the satellite at different angles and, therefore, the cells on each side will be producing different amounts of power. The optimal solution lies somewhere between adding components to the circuit to match the voltages coming off each side, thereby losing more power to component inefficiencies and to powering the components themselves, or just combining the mismatched voltages and losing some to internal dissipation. Once the electricity has been generated, it will be stored in batteries until such time as it is needed.
The distribution of power to the satellite has to be carefully budgeted, since the amount which can be produced and stored at a given time is very limited. Since we are currently in the early phases of a new mission, the budget is currently being reworked to account for our new propulsion system, which requires a lot of power.