Propulsion Power Distribution Module - Terma

Propulsion Power Distribution ModuleSPACEFor generation and distribution of redundant 29 volt buslines to Galileo spacecraft propulsion equipments aPropulsion Power Distribution (PPD) module isavailable. The module provides two independent 29 voltsupply lines and four 50 volt Latching Current Limiters(LCL), each one followed by a series switch.From a regulated 50 volt bus two independent DC/DCconverters generate redundant regulated 29 volt bussescompatible with spacecraft equipments designed for 28 voltbus applications.For other applications e.g. local heaters, the module providesfour LCLs, each one followed by a separate series switch toensure no permanent failure mode.Each switch function can be commanded on/off via a dualcommand & monitoring bus, distributed by a backplaneinterface. Each switch provides telemetry of switch statusand load current.In case of overload or short circuit, the output current isinstantly limited to protect the upstream main power bus.When exceeding a predefined delay the LCL willautomatically switch off.The voltage drop for each switch function is compatible withrequirements for a regulated 28 or 50 volt bus.Each LCL on the module is fully self-contained with provenno failure propagation in-between, thus eliminating the needfor “A and B sides” in the distribution function. The moduleforms an autonomy function deriving its internal supplyvoltages directly from the power bus.References:• One module onboard each of the four Galileo IOVspacecrafts. The first two spacecrafts were launched inOctober 2011Propulsion Power Distribution ModuleSpace Engineering and Knowledge

Specifications:Dimensions (L x W x H)193 x 150 x 24 [mm]Mass528 gramBus voltage50 volt29V Redundant BusOutput voltage29 +/-1.1 voltPower capability2 x 75 wattEfficiency at full power 92.9%Load transient @ 50% load step < 0.5V50V Bus DistributionNumber of LCL Blocks 4LCL load current class1.0 AmpereLCL trip off & current limitation level +5 % to +15 %Switch trip off delay11 +/-1 msSwitch current regulation response< 500 nsSeries Switches 4Idle consumption, all switches off< 0.75 wattLoad current TM inaccuracy < 5 %Propulsion Power DistributionRNMBIDC/DC ConverterAuxSupplyIV29V output1N+1RPWMControlOnOffCurrent LimitationRefOVPCSEnableCMB Power Distribution#2#1I4 outputs2N+2ROnOffCCSOnOffC C SPropulsion Power Distribution Module Functional SchematicTerma A/S Spacewww.terma.com