power control system for the agile satellite… 2005 presentation.pdf · power control system for...

POWER CONTROL SYSTEM FOR THE AGILE SATELLITE

G. Ebale, A. Lamantia, M. La Bella

Blu Electronic s.r.l. via Gallarate,150. 20151 Milano (Italy)

7th European Space Power Conference May 97th European Space Power Conference May 9--13, 2005 13, 2005 StresaStresa, Italy, Italy


Introduction

AGILE (Astrorivelatore Gamma a Immagini Leggero) main features:detects and images photons in the 30 [MeV] ÷ 50 [GeV] and 10–40 [keV] energy bands.

excellent spatial resolution and timing capabilityextremely large field of view covering 15% of the entire sky at energies above 30 [MeV]based on an innovative design allowing the simultaneous detection of hard X-rays and gamma-rays with high imaging and timing capabilities


Additional technical data

Required orbit: Equatorial (550 km)Total mass: 300-330 kgPayload absorbed power: 130 WSatellite expected orbit life: 2 yearsOrbit period: 95,65 min.Average lighting time is 60.31min.Maximum eclipse time is 35.4 min.


PEB (Power Electronic Box) features

Solar Array Power managingBattery reconditioningPower distribution to the PayloadPower distribution to the OBDHPower Distribution to the ACS, ORBCOMM, TMTC communication systemPower distribution to the battery and payload heatersI/F ing with the OBDH (TLC/FLAG/HKM)OVC/OVV detection on the power distribution lines


PEB specificationsUnregulated main bus: 22.5÷35VDCMaximum battery voltage: 34VMaximun battery charge/discharge current: 12 ANominal battery charge/discharge current: 8 AOBDH maximum power consumption: 30WPAYLOAD (gamma ray detector and the associated electronics)maximum power consumption: 130WPEB maximum power consumption: 70WOther satellite loads: 100W

momentum wheelmagnetic torquesmagnetometersbattery and payload heatersOrbcommTMTC communication system

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POWER SYSTEM ARCHITECTURE


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Solar array features:Maximum dimensions:

2080 mm (width)1050 mm (length)26 mm (thickness)

Electrical structure:14 electrical sections per panel.6 sections type with 5 strings8 sections type with 1 string.Strings formed with 13 solar cells.

404,8 23,19 17,455 EOL @ 90

580,79 36,43 15,942 EOL @ -90

435,39 23,8 18,285 BOL @ 90

601,68 37,41 16,084 BOL @ -90

[W] [V] [A][°C]

PmaxVmpImpT


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Solar array curves:


BOL EOL

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Battery features:

Battery type: 11 NiH2 cells in seriesBattery capacity: 10 °C is 12 Ah (330 Wh)Battery nominal voltage: 27.5 VBattery maximum voltage: 34VNominal Charge current: from 6 to 8 AMaximum Charge/discharge current: 12 AAverage power that the battery shall supply in the eclipse periods is: 195 WPeak power is approximately: 230 W .


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Battery reconditioning

PS board

S3R philosophyInternal logic to manage the redundancy of the CR boardsSolar Array current and voltage monitorInternal fold back circuits against auxiliary power supply short circuitLatch up protection


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CR board

Boost topologyInternal logic to manage the MPPT functionInput, output, battery current monitorBattery voltage monitorBattery OVV, OVC, OVD detectionInternal fold back circuits against auxiliary power supply short circuitLatch up protection


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Redundancy philosophy

Two redundant Power Switches (PSM and PSR) control two redundant Charge Regulators (CRM and CRR) providing the Solar Array (SA) power to the battery and to the main bus. CRM and CRR can manage about 8 A each to charge the battery, if the battery needs more current they can work in parallel mode to supply about 12 A


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PEB Operational ModesPos 1: Psa > Pbat+ Pmb, the system works in S3R domain controlling the total current within the battery.Pos 2: Psa < Pmb+Pbat, a Maximum Power Point Tracking (MPPT) mode controls the battery charging current.Pos 3: Psa <Pmb, the current delivered to the node ‘battery + main bus’ is controlled at 8A in the S3R domainPos 4: Psa@Vbat<Pbat,theMaximum Power Point Tracking (MPPT) mode is utilised again to control the current delivered to the node “battery+main bus”(Fig. 3 pos 4).


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Error signal domain

S3R: 6 high current section with a very large hysteresis for the switch on threshold and switch off threshold (10V).CR mode with maximum power point tracking


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Error signal response to load variation 0,5 A section

Error signal variation

load variation1A/div

Main bus variation200mV/div


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Error signal response to load variation 2,5 A section


Error signal variation



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Error signal response to load variation CR




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Power DistributionIn order to supply power to the satellite different distributionboards directly connected to the unregulated bus have beenforeseen

DC/DC board:supplies internal and external auxiliary voltages:

±15V12V isolated5V

main and redundant electrically and thermally separated linesUndervoltage and overvoltage protectionCurrent monitoring


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PR board

Connected to the battery bus through the separation switches by redundant and fault tolerant linear regulators in order to perform basic operations if internal power supply is not availableconnects the internal DC/DC converters to the power bus by latching relays and performs a switch over from nominal to redundant DC/DC converter branches in the case of a failure detection (input over-current, output under or over voltage). provides power distribution to the OBDH main and redundant protected power linesperforms switching and OR-ing of the PEB internal supply lines.Fold back protection circuits for the auxiliary power supply


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PD board

Supply power to the external loads through dedicated power linesMAIN and the RED branches designed to guarantee separation between the two branches from an electrical and thermal point of view.Primary power lines distributed from the PEB individually protected against short circuit through series n-channel power MOS and dedicated current sensing circuits.


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Cross-trapping philosophy for the vital loads nominal and redundant equipment (receivers and transmitters)fold-back current limiters for the auxiliary supply


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PL board

Supplies power to the external payload through dedicated power linesSupplies power to the external payload heatersMAIN and the RED branches designed to guarantee separation between the two branches from an electrical and thermal point of view.Primary power lines distributed from the PEB individually protected against short circuit through series n-channel power MOS and dedicated current sensing circuits.controls the payload in-rush current providing power to the load following a ramp wave-shape


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HK board

Collects and provides to the OBDH all the internal analog monitorsMain and redundant philosophy.Cross trapping of the main and analog monitors.Fold back circuits for the auxiliary power supply

Mux main

Mux red

Analog main

Analog red

OBDH main

OBDH red

HK


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PC board

Performs OBDH commands via RS422 lines.Collects and provides to the OBDH all the internal digital flagsPerforms high priority commands via differential linesHot redundancy philosophy for both RX and TX functionsInternal opto isolation respect to the RX and TX lines.Fold back circuits for the auxiliary power supplyLatch up protection for the logic


power control system for the agile satellite… 2005 presentation.pdf · power control system for...

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