Design and Implementation of On-board Electrical Power ... - OUFTI-1

subsystems must be supplied with 3.3V, 5V, and/or 7.2V. The EPS has a power conditioningunit, able to deliver the required amount of electrical power at these voltages.The EPS secondary functions.Some important voltages, currents, and temperatures (they are called the ”HousekeepingParameters”) are measured, scaled, converted from analogical to digital, and transferred toan I 2 C bus. The EPS gathers measurements of its own parameters, but also the temperatureof the external faces of the CubeSat.The switches controlling the current for the antenna’s deployment are on the EPS.Heavy radiations can cause ”single event latch-up” in the semiconductor devices on thesatellite. This can burn the component if the power is not turned off quickly enough. Protectingthe power outputs against over-currents was initially one of the secondary functionsof the EPS. The choice has been made to place such protection circuits on other cards, onthe power input of each system. So, the power can be turned on and off for each systemindependently.In short, the primary functions of the EPS are:• Power source• Power storage• Power conditioning and distribution.The secondary functions of the EPS are:• Telemetry measurements and conditioning• Power control of the antenna’s deployment system• Over-current protection (located on user’s cards).11