POWER CONTROL SYSTEM FOR THE AGILE SATELLITE G. Ebale, A. - - PowerPoint PPT Presentation

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POWER CONTROL SYSTEM FOR THE AGILE SATELLITE G. Ebale, A. - - PowerPoint PPT Presentation

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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 9- -13, 2005 13, 2005 Stresa Stresa, Italy , Italy

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SLIDE 1

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 9 7th European Space Power Conference May 9-

  • 13, 2005

13, 2005 Stresa Stresa, Italy , Italy

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SLIDE 2

2 7th European Space Power Conference May 9 7th European Space Power Conference May 9-

  • 13, 2005

13, 2005 Stresa Stresa, 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 capability extremely large field of view covering 15% of the entire sky at

energies above 30 [MeV]

based on an innovative design allowing the simultaneous detection

  • f hard X-rays and gamma-rays with high imaging and timing

capabilities

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SLIDE 3

3 7th European Space Power Conference May 9 7th European Space Power Conference May 9-

  • 13, 2005

13, 2005 Stresa Stresa, Italy , Italy

Additional technical data

Required orbit: Equatorial (550 km) Total mass: 300-330 kg Payload absorbed power: 130 W Satellite expected orbit life: 2 years Orbit period: 95,65 min. Average lighting time is 60.31min. Maximum eclipse time is 35.4 min.

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4 7th European Space Power Conference May 9 7th European Space Power Conference May 9-

  • 13, 2005

13, 2005 Stresa Stresa, Italy , Italy

PEB (Power Electronic Box) features

Solar Array Power managing Battery reconditioning Power distribution to the Payload Power distribution to the OBDH Power Distribution to the ACS, ORBCOMM, TMTC

communication system

Power distribution to the battery and payload heaters I/F ing with the OBDH (TLC/FLAG/HKM) OVC/OVV detection on the power distribution lines

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  • 13, 2005

13, 2005 Stresa Stresa, Italy , Italy

PEB specifications

  • Unregulated main bus: 22.5÷35VDC
  • Maximum battery voltage: 34V
  • Maximun battery charge/discharge current: 12 A
  • Nominal battery charge/discharge current: 8 A
  • OBDH maximum power consumption: 30W
  • PAYLOAD (gamma ray detector and the associated electronics)

maximum power consumption: 130W

  • PEB maximum power consumption: 70W
  • Other satellite loads: 100W

momentum wheel magnetic torques magnetometers battery and payload heaters Orbcomm TMTC communication system

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SLIDE 6

6

POWER SYSTEM ARCHITECTURE

7th European Space Power Conference May 9 7th European Space Power Conference May 9-

  • 13, 2005

13, 2005 Stresa Stresa, Italy , Italy

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SLIDE 7

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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

strings

8 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] Pmax Vmp Imp T

7th European Space Power Conference May 9 7th European Space Power Conference May 9-

  • 13, 2005

13, 2005 Stresa Stresa, Italy , Italy

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SLIDE 8

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Solar array curves:

7th European Space Power Conference May 9 7th European Space Power Conference May 9-

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13, 2005 Stresa Stresa, Italy , Italy

BOL EOL

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SLIDE 9

9

Battery features:

Battery type: 11 NiH2 cells in series Battery capacity: 10 °C is 12 Ah (330 Wh) Battery nominal voltage: 27.5 V Battery maximum voltage: 34V Nominal Charge current: from 6 to 8 A Maximum Charge/discharge current: 12 A Average power that the battery shall supply in the

eclipse periods is: 195 W

Peak power is approximately: 230 W .

7th European Space Power Conference May 9 7th European Space Power Conference May 9-

  • 13, 2005

13, 2005 Stresa Stresa, Italy , Italy

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SLIDE 10

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Battery reconditioning

PS board

S3R philosophy Internal logic to manage the redundancy of the CR boards Solar Array current and voltage monitor Internal fold back circuits against auxiliary power supply short

circuit

Latch up protection

7th European Space Power Conference May 9 7th European Space Power Conference May 9-

  • 13, 2005

13, 2005 Stresa Stresa, Italy , Italy

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SLIDE 11

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CR board

Boost topology Internal logic to manage the MPPT function Input, output, battery current monitor Battery voltage monitor Battery OVV, OVC, OVD detection Internal fold back circuits against auxiliary power

supply short circuit

Latch up protection

7th European Space Power Conference May 9 7th European Space Power Conference May 9-

  • 13, 2005

13, 2005 Stresa Stresa, Italy , Italy

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SLIDE 12

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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

7th European Space Power Conference May 9 7th European Space Power Conference May 9-

  • 13, 2005

13, 2005 Stresa Stresa, Italy , Italy

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SLIDE 13

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PEB Operational Modes

  • Pos 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 domain

  • Pos 4: Psa@Vbat<Pbat,the

Maximum Power Point Tracking (MPPT) mode is utilised again to control the current delivered to the node “battery+main bus” (Fig. 3 pos 4).

7th European Space Power Conference May 9 7th European Space Power Conference May 9-

  • 13, 2005

13, 2005 Stresa Stresa, Italy , Italy

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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

7th European Space Power Conference May 9 7th European Space Power Conference May 9-

  • 13, 2005

13, 2005 Stresa Stresa, Italy , Italy

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Error signal response to load variation 0,5 A section

Error signal variation load variation 1A/div Main bus variation 200mV/div

7th European Space Power Conference May 9 7th European Space Power Conference May 9-

  • 13, 2005

13, 2005 Stresa Stresa, Italy , Italy

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Error signal response to load variation 2,5 A section

Main bus variation 500mV/div Error signal variation load variation 2A/div

7th European Space Power Conference May 9 7th European Space Power Conference May 9-

  • 13, 2005

13, 2005 Stresa Stresa, Italy , Italy

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SLIDE 17

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Error signal response to load variation CR

7th European Space Power Conference May 9 7th European Space Power Conference May 9-

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13, 2005 Stresa Stresa, Italy , Italy

Main bus variation 200mV/div load variation 2A/div

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Power Distribution

In order to supply power to the satellite different distribution boards directly connected to the unregulated bus have been foreseen

DC/DC board:

supplies internal and external auxiliary voltages:

±15V 12V isolated 5V

main and redundant electrically and thermally separated lines Undervoltage and overvoltage protection Current monitoring

7th European Space Power Conference May 9 7th European Space Power Conference May 9-

  • 13, 2005

13, 2005 Stresa Stresa, Italy , Italy

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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 available

connects 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 lines

performs switching and OR-ing of the PEB internal supply lines. Fold back protection circuits for the auxiliary power supply

7th European Space Power Conference May 9 7th European Space Power Conference May 9-

  • 13, 2005

13, 2005 Stresa Stresa, Italy , Italy

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PD board

Supply power to the

external loads through dedicated power lines

MAIN 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.

7th European Space Power Conference May 9 7th European Space Power Conference May 9-

  • 13, 2005

13, 2005 Stresa Stresa, Italy , Italy

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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

7th European Space Power Conference May 9 7th European Space Power Conference May 9-

  • 13, 2005

13, 2005 Stresa Stresa, Italy , Italy

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PL board

Supplies power to the external payload

through dedicated power lines

Supplies power to the external payload

heaters

MAIN 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

7th European Space Power Conference May 9 7th European Space Power Conference May 9-

  • 13, 2005

13, 2005 Stresa Stresa, Italy , Italy

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HK board

Collects and provides to the OBDH all the internal

analog monitors

Main 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

7th European Space Power Conference May 9 7th European Space Power Conference May 9-

  • 13, 2005

13, 2005 Stresa Stresa, Italy , Italy

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PC board

Performs OBDH commands via RS422 lines. Collects and provides to the OBDH all the internal digital

flags

Performs high priority commands via differential lines Hot redundancy philosophy for both RX and TX functions Internal opto isolation respect to the RX and TX lines. Fold back circuits for the auxiliary power supply Latch up protection for the logic

7th European Space Power Conference May 9 7th European Space Power Conference May 9-

  • 13, 2005

13, 2005 Stresa Stresa, Italy , Italy