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DC/DC converters

The power system provides necessary regulated Voltage for the functioning of different Sub-system of the spacecraft via the DC/DC converter. The number of DC/DC converter has to maximized for the load isolation and to be minimized because of the limitation on mass, volume and complexity.

The load of the satellite is of three types 1. Continuous 2. Payload (switchable) and 3.redundant. Hence it preferred to choose a maximum of three DC/DC converters one for each payload. The starting bias will be obtained directly from the raw bus. The controller has to maintain the output voltage under wide variation of bus voltage and load current. The voltage regulation is maintained during opening and closing of the peak loads. The converter is designed to operate with sufficient stability margin to compensate for parameter variation due to temperature and aging. The configuration and the scheme of control are chosen to provide simplicity, high efficiency and good regulation ( + 3%).

The Telecommand and Telemetry Interfaces

The TM interface consists of defining optimum number of parameters to be monitored to give maximum information about the power system. The TC interface for the power system consists of a safety command (a pulse command) for e.g. to put the K- relay, to internal position and two commands to enable and disable the automatic battery protection logic. Two more commands are introduced for switching OFF the payloads during de-tumbling and to switch the S&F TX whenever required.

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