Cryomagnetic Avionics Box

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Cryomagnetic Avionics Box
Short Overview and Status
Gert Viertel (ETH-Zurich) January 2004
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CAB Responsibilities
CAN Bus Connection
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Cryomagnet Avionics Box (CAB)
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AMS-02 STS Power Distribution Block Diagram
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Functionality

• CAB is the main interface between the AMS control
  and power distribution system on one side and the
  AMS cryomagnet on the other side. Its main
  functions are
• Charging and discharging the magnet
• Protection of the AMS cryomagnet under any
  unwanted conditions, including a magnet
  quench
• Supervision of the cryogenics system
• Providing an interface to the AMS slow control
  system
• Providing 5.5 kV interface protection between
  the cryomagnet and ISS

• The functionality is split between three
  subsystems
• Cryomagnet Current Source (CCS)
• Cryomagnet Self Protection (CSP)
• Cryomagnet Controller and Signal Conditioner
  (CCSC)

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Cryomagnet Current Source (CCS)

• Magnet ramping mode (AMS-02 powered down to its
  minimum)
• Convert the ISS high voltage (107 V 127 V) to
  a low voltage between
• 1.0 V and 3.3 V at up to 455 A for
  cryomagnet charging
• With increasing current the output voltage drops
  in order to keep the
• power consumption below 1875 W.

• Experiment mode (CCS is powered down)
• CCS semi-conductor switch is OPEN in order to
• prevent current circulation through the CCS
  which would cause an excessive power consumption
  of the CAB
• prevent a magnet discharge from taking several
  hours

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Cryomagnet Current Source CCS and Magnet Load
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Cryomagnet Self Protection (CSP)

• The CSP is maintained operational also in case of
  an external power loss by means of an UPS in
  order to provide the following functionality
• Quench detection and quench heaters activation
• Auto ramp-down in case of communication and/or
  external power loss
• Permitting OCP (Operations Command Posts)
  control of all CAB
• functions
• Identifies the coil section initiating a quench
• Permit an autonomous operation of all important
  CAB functions
• quench heaters
• current lead dis-connectors
• current lead valves
• vapour cooled shield vent valves
• cool down circuit vent valves
• current lead TMP (Thermo-Mechanical Pump) heater
• cool-down TMP heater and persistent switch
  heater

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CSP Functional Block Diagram
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Cryomagnet Dump Diodes (CDD)

• In the event that the magnet must be powered
  down, the persistent switch will be opened to
  allow the current in the magnet to be dumped to a
  bank of 18 rectifiers (six sets in series of
  three rectifiers in parallel)
• These rectifiers will be protected by a cover to
  prevent incidental contact
• The rectifiers will be mounted on the two
  wake-side sill trunnion joints (large thermal
  mass)
• Worst case thermal analysis reveals that with a
  continuous load rectifiers will maintain junction
  temps well below ratings even if one of a
  parallel series of three fail.
• Dump time is estimated at 80 minutes

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Cryomagnet Dump Diodes
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Cryomagnet Dump Diode Mounting Locations
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Cryomagnet Controller and Signal Conditioner
(CCSC)

• CAB interface to the AMS-wide redundant CAN-BUS
  providing
• Control of the CCS
• Telemetry of the magnet cryogenics including
  temperatures and pressures
• and of the CAB Status.
• Control of the power switches
• Control and monitoring for the Direct Liquid
  Content Measurement
• Control of charging of the Uninterruptible Power
  Source (UPS) and
• relaying of telemetry from the UPS

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Uninterruptible Power Source (UPS)

• The UPS will consist of a redundant set of
  Lithium-Ion batteries
• Battery will provide control power during loss of
  ISS power or communication to payload for mission
  success
• Watch-dog timer/control circuit
• Normal Ramp down function
• Quench monitoring
• Initiation of quench, 45A pulse
• Battery is designed to meet NSTS 1700.7B, "Safety
  Policy and Requirements For Payloads Using the
  Space Transportation System", NSTS 1700.7B ISS
  Addendum, "Safety Policy and Requirements For
  Payloads Using the International Space Station",
  and JSC 20793, "Manned Space Vehicle Battery
  Safety Handbook and will be sized for a minimum
  of 8 hours of operation, plus ramp-down time

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Battery Cell Characteristics

• Manufactured by Yardney/Lithion
• Prismatic cell
• Dimensions 95mm (3.74) X 27.84mm (1.096) X
  139.7mm (5.500)
• Weight 900g (1.982 lbs)
• Operational Temperature Range -30 degC to 50
  degC

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Interfaces

• Input power interface
• main power input to the Cryomagnet Current
  Source (CCS) 107 lt-gt 127 VDC
• 28 VDC supply (PDS) for relays and heaters and
  conversion within the CAB to other
• internally required voltages

• Control interface
• AMS redundant CAN-Bus for interface and control

• Cryomagnetic sensors
• Temperature sensors, current lead voltage taps,
  control valve positions, thermo mechanical
• pump currents and voltages, power consumption,
  vacuum case vacuum sensors,
• helium pressure sensors

• Cryomagnet control
• Cryogenic and warm valves, quench heaters,
  persistent switches, helium tank heaters,
• current lead dis-connectors, thermo-mechanical
  pump heaters

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Weight, Dimensions, Power, Temperature Limits
Total weight 43640 g 10 contingency ? 48000 g

• Power consumption
• CCS is not charging the magnet lt 45 W
• CCS is charging the magnet lt 2000 W

• Temperature limits
• Storage -40 oC to 70 oC
• Operating -40 oC to 60 oC

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Up-dated Electrical Specifications from B.
Anderson (SCL)
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AMS-02 CAB Progress Report 15 July 2003

• Electrical
• Software
• Mechanical
• Thermal
• Programmatic
• Managerial

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ELECTRICAL

• Cryomagnet Current Source Subsystem (CCS)
• DC/DC Power Converters (CCS_CS module)
• Electrical Design DONE
• Worst Case AnalysisDONE
• Parts Stress Analysis DONE (on the critical EEE
  parts gt100mW)
• Failure analysis DONE
• PCB layout in progress
• Control TM/TC (CCS_CTRL TMTC module)
• Electrical Design DONE
• Worst Case AnalysisDONE
• Parts Stress Analysis DONE (on the critical EEE
  parts gt100mW)
• Failure analysis DONE
• PCB layout in progress

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Electrical
ELECTRICAL

• Cryo Controller Signal Conditioner Subsystem
  (CCSC)
• Standard Telemetry (CCSC_STM module)
• Standard Telemetry Function
• Electrical Design DONE
• Worst Case AnalysisDONE
• Parts Stress Analysis DONE (on the critical EEE
  parts gt100mW)
• Failure analysis DONE
• CPU Function
• Electrical Design Pending to include the last
  modifications
• Worst Case AnalysisDONE
• Parts Stress Analysis DONE (on the critical EEE
  parts gt100mW)
• Failure analysis DONE
• DC/DC Converter
• Electrical Design DONE
• Worst Case AnalysisDONE
• Parts Stress Analysis DONE (on the critical EEE
  parts gt100mW)
• Failure analysis DONE
• PCB layout not yet started waiting for the
  "Valves Status Monitoring" definition. It affects
  to STM function

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ELECTRICAL

• Power Switches Subsystem (PS module)
• PS TM/TC Power Drivers Function
• Electrical Design DONE
• Worst Case AnalysisDONE
• Parts Stress Analysis DONE (on the critical EEE
  parts gt100mW)
• Failure analysis DONE
• PS DC/DC Converter Function
• Electrical Design DONE
• Worst Case AnalysisDONE
• Parts Stress Analysis DONE (on the critical EEE
  parts gt100mW)
• Failure analysis DONE
• PCB layout not yet started waiting for the "Warm
  Valves" choice and the "Valves Status" monitoring
  definition.

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ELECTRICAL

• 28V_ISO module
• Detailed Electrical Design in progress
• Worst Case Analysisin progress
• Parts Stress Analysis in progress (on the
  critical EEE parts gt100mW)
• Failure analysis DONE

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ELECTRICAL

• Cryomagnet Self Protection Subsystem (CSP)
• CSP Power Drivers (CSP_PWR_DRV module)
• Electrical Design DONE
• Worst Case AnalysisDONE
• Parts Stress Analysis DONE (on the critical EEE
  parts gt100mW)
• Failure analysis DONE
• PCB layout PCB layout not yet started waiting
  for the "Warm Valves" choice.
• CSP TM/TC /CSP_TMTC module)
• Electrical Design Very poor advance. Still
  waiting for the "Valves Status" monitoring
  definition and for the closure of the definition
  of Autonomous quench recovery sequence regarding
  to the small flight vent valves DV08A to DV08D
  and DV15A to DV15D
• Failure analysis in progress, at block level

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ELECTRICAL

• Cryomagnet Self Protection Subsystem (CSP)
• Current Lead Detectors (CSP_CL_DET module)
• Electrical Design DONE
• Worst Case AnalysisDONE
• Parts Stress Analysis DONE (on the critical EEE
  parts gt100mW)
• Failure analysis DONE
• PCB layout not yet started. Analysis of the
  layout to keep the 2KV Isolation in progress
• Magnet Detectors (CSP_MAG_DET module)
• Electrical Design DONE
• Worst Case AnalysisDONE
• Parts Stress Analysis DONE (on the critical EEE
  parts gt100mW)
• Failure analysis DONE
• PCB layout not yet started. Analysis of the
  layout to keep the 2KV Isolation in progress

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ELECTRICAL

• Cryomagnet Self Protection Subsystem (CSP)
• Detectors DC/DC Converter (CSP_DET_CV module)
• Electrical Design DONE
• Worst Case AnalysisDONE
• Parts Stress Analysis DONE (on the critical EEE
  parts gt100mW)
• Failure analysis DONE
• PCB layout not yet started. Analysis of the
  layout to keep the 2KV Isolation in progress

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SOFTWARE

• The SW development has started and the following
  documents have been produced
• CAB HW/SW ICD. Delivered for comments
• Software Requirements Document (SRD), in internal
  signatures cycling. To be issued before end of
  July 2003.
• Software Interface Control Document (SICD), in
  internal signatures cycling . To be issued before
  end of July 2003.
• Next
• Architectural and Design Document
• Coding phase

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MECHANICAL
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MECHANICAL

• CAB boards location

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MECHANICAL
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MECHANICAL
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MECHANICAL
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MECHANICAL
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MECHANICAL

• FIRST NATURAL FREQUENCY ON Y AXIS IN THE PLOT AT
  126 HZ

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THERMAL

• This information was provided during the TIM at
  CERN on April 2003
• CAB Power Budget
• Conditions
• Both nominal and redundant 28V busses turned on,
  in hot redundancy
• No external heater or valve activated and the CCS
  current source turned off
• Only CAB internal consumption has been considered
• (All the CAB nominal and redundant modules are
  being supplied)
• Typical power consumption of the CAB unit in
  standby mode 67 Watts
• Maximum power consumption of the CAB unit in WCA
  80 Watts
• (CAB unit in operating mode including temperature
  effects)
• In Cold Redundancy (only nominal 28V Primary bus
  ON)
• Maximum power consumption of the CAB unit in WCA
  50 Watts
• (CAB unit in operating mode including temperature
  effects)
• Additionally 280W max full load (final period of
  ramp-up process) of the CCS current Source and
  42W max of the current shunt

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THERMAL

• AMS CAB THERMAL DESIGN
• Box fixed onto a AMS USS Beams (Dec.2002)
• thermally connected
• conductively to USS
• AMS CAB POWER INPUT
• CCS TRANSIENT RAMP UP
• CONTROL STEADY STATE
• AMS SURROUNDINGOUTER SPACE (NOMINAL COLD
  HOT) 
• AMS CAB BOUNDARIES (CGS e-mail February 26th
  2003)
• HEAT LOADS FROM AMS AND OUTER SPACE (NOMINAL
  COLD HOT)
• RADIATION INHIBIT BY BETHA COLTH
• CONDUCTION TO UPPER TRUNNION MAIN PATH
• CONDUCTION TO LOWER TRUNNION NEGLECTED (SPRING)
• CASES STUDIED
• CONDUCTANCE FROM CAB TO UPPER TRUNION 1W/ºC
• TWO SCREWS SIMULATING POOR COUPLING
• CONDUCTANCE FROM CAB TO UPPER TRUNION 3W/ºC
• SIX SCREWS SIMULATING GOOD COUPLING

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THERMAL

• RESULTS COMPARISON
• Three environmental conditions studied with two
  conductive couplings.
• NOMINAL
• REACHED STEADY STATE CONDITION WITH 6 SCREWS
• HOT
• NOT REACHED STEADY STATE CONDITIONS WITH 6 SCREWS
• COLD
• REACHED STEADY STATE CONDITIONS WITH 6 SCREWS
• NONE OF CASES WITH 2 SCREWS CAN WITHSTAND
  PERMANENT OPERATION.
• CONCLUSIONS
• It is necessary a good coupling (equal or better
  than 8 screws) with the AMS upper trunnion in
  order to provide enough heat sinking capabilities
  to drain the total heat loads in steady state
  condition (around 100w).

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THERMAL

• Results of Thermal Analysis RadiativeConductive
  Exchange

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THERMAL

• Temperatures Prediction

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Status Summary January 2004

• Up-dated specifications for CAB from SCL
• Mounting Design for the CAB on USS
• CRISA CGS Iterations of the thermal model in
  progress
• Data on some components still missing to finalise
  the CAB design
• New Version of the Final Technical Proposal
  submitted by CRISA
• Deliverables EM FM (Both fully functional)