The main objective of the Power Distribution Unit (PDU) is to supply electrical power to the subsystems and payloads of the satellite and to prevent the overload of the main power bus.
Power distribution with high reliability and built-in overload protection
The PDU consists of two identical units (the main and the redundant) that are interfaced with each other in order to provide the required redundancy. Both motherboards are interfaced with the Power Management Unit (PMU) of the satellite by redundant synchronous serial Low-Voltage Differential Signalling (LVDS) lines using a full cross-strapping redundancy scheme. In order to manage the power distribution and prevention functions each payload and subsystem has a dedicated Latched Current Limiter (LCL) circuit which connects them to the main power bus. An individual current limit and undervoltage protection level is defined for every LCL as referred by the requirements of the payload or the subsystem. The control function of the PDU is managed by an FPGA, using CRC protected communication interfaces and combinational logic network in it. The FPGA controls the LCLs with individual ON and OFF command interfaces, furthermore collects and processes their telemetry by reading the telemetry interfaces of the LCLs. Since the main and the redundant PDU unit are interfaced with each other every single LCL, including the command and the telemetry interfaces, can be accessed and managed by both PDU section so the prevention against any single-point errors can be realized.
Dr József Szabó
szabo @ hvt.bme.hu