Power Supply

The electrical power supply of the Flying Laptop is facilitated by three solar panels, which were manufactured by Airbus Defence and Space. One solar panel is body mounted, two are deployed once the satellite is launched and separated from the launcher. The bus voltage is unregulated between 19V and 26V. The necessary voltage for every component is obtained by DC/DC converters dedicated to every unit.

The Power Control and Distribution Unit (PCDU) was manufactured by Vectronic Aerospace. It detects the launcher separation, controls the power distribution to the components and adjusts the charging of the battery. Beyond these default operations the PCDU executes further tasks. The PCDU collects data, currents and voltages of a majority of the satellite´s sensors and forwards them to the On-Board Computer (OBC) for further processing. Together with the OBC system the PCDU is one of the central controlling units, which can switch over to the redundant unit branch in case of an emergency. In particular, the PCDU can activate the available redundant units in case there is a breakdown of the OBC. The PCDU features dedicated input interfaces for High Priority Commands (HPCs). The HPCs are decoded and sent to the PCDU without involving the OBC. Thus, essential telecommands can be received and executed by the PCDU, fulfilling its purpose as a backup system.

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As a secondary power source, the FLP is equipped with a battery (see image). It consists of three independent battery strings made of Lithiumironphosphate cells manufactured by A123 Systems (type ANR26650M1-B). Each of these strings is directly connected to one of the solar panels. As the middle body mounted solar panel generates less power than the wing panels, the battery string for this panel consists of 28 cells, whereas the strings for the wing panels consist of 35 cells each. In total, a voltage of 19V to 26V is yielded at a total capacity of all strings combined of roughly 700Wh. Additional circuitry is used to balance the cell voltages and to send a signal to stop charging to the PCDU if the voltage of one cell reaches the maximum allowed value. The battery is used to supply power to the satellite system during eclipse and to provide additional energy during maneoeuvres in which the power consumption of the system exceeds the power generated by the solar panels.