The UoSAT-2 spacecraft power system

Four panels of Si solar cells provide power to charge packs of NiCd battery cells via a battery charge regulator. Regulated + 10 V, ¿ 10 V and + 5 V supplies from a centralized power regulating system, as well as + 14 V unregulated battery voltage, are supplied to a power distribution module which uses bipolar transistors to switch power as required to different loads. As UoSAT is in eclipse for over one-third of its orbit, batteries with good cyclic performance must be provided. UoSAT-2 operates on a negative power budget where the power required to keep all systems fully operational is greater than the solar power available. Consequently, significant groundstation effort is required to monitor and manage the power system. Future satellites may incorporate a microprocessor-driven control element in a further step towards system autonomy.