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LHC Power Converter Controls

LHC Power Converter Controls. Real-time control for Closed Orbit Feedback Mini-workshop presentation. How many Front Ends?. 1712 Power Converters (PC) in LHC 752 for COD PCs in tunnel One Function Generator/Controller (FGC) per PC Up to 30 FGCs per WorldFIP fieldbus

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LHC Power Converter Controls

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  1. LHC Power Converter Controls Real-time control for Closed Orbit Feedback Mini-workshop presentation AB-PO-CC

  2. How many Front Ends? • 1712 Power Converters (PC) in LHC • 752 for COD PCs in tunnel • One Function Generator/Controller (FGC) per PC • Up to 30 FGCs per WorldFIP fieldbus • One Gateway (front end) per fieldbus • 10 Gateways per IP, 80 for LHC AB-PO-CC

  3. What/where are the Gateways? • Gateways will be rack mounted Intel PCs • They will be installed on the surface with fibre links to the underground areas • COD PCs are grouped in fours (H/V B1/2) • One group per LHC cell (100m) • FIP cable lengths are up to 800m, so copper-copper WFIP repeaters will be needed in the tunnel (500m is the limit) AB-PO-CC

  4. Architecture Loggingapplications Alarmsystem Commandapplications DB RTdisplays RTServer(s)(1-5) CMW Diagnosticapplications RT feedbackapplications FGC Gateways (80) Time of dayms events50 Hz synch Post mortem WorldFIP Fieldbuses Function Generator/Controllers (1712) Fast dataacquisition Dumbterminal AB-PO-CC

  5. Real-time communications • One 32-bit floating-point number per FGC per WorldFIP cycle • Exclusive access to RT channel will be assured by RT server • UDP/IP for transport from applications to RT-server and from RT-server to Gateways • WorldFIP to FGCs AB-PO-CC

  6. WorldFIP bottleneck • WorldFIP network runs at 2.5Mbps but interface chip (FullFIP2) was designed as a 1Mbps device • Interface to host processor (Intel P4) cannot keep up with network transfer rate. • We must reduce FIP cycle from 10ms to 20ms to work around communication bottleneck within the Gateway’s WorldFIP interface • 50Hz operation more than enough but care with synchronisation will be required AB-PO-CC

  7. Function Generation for Current The predefined contribution to the reference has only two basic states: 1. HOLDING 2. CHANGING I(t) Change starts at “held” value New change loaded Event triggers new change Change completed & forgotten time AB-PO-CC

  8. Real-time control options 1. The current reference can be completely predefined: Iref = I(t) 2. The current reference can be the sum of predefined and real-time parts: Iref = I(t) + Irt 3. The current reference can be the product of predefined and real-time parts: Iref = I(t).Grt 4. The current reference can be completely defined in real-time: Iref = Irt AB-PO-CC

  9. Area Number of FGCs Estimated Flux of hadrons > 20 MeV Estimated Dose Rate Under Arc cryostats 752 < 1010 /cm2/year 2-10 Grays/year RRs 262 < 108 /cm2/year 0.1 Grays/year UAs & SRs 705 ~ 0 /cm2/year ~ 0 Grays/year The Radiation Problem in LHC AB-PO-CC

  10. Tunnel Operation • 2-10 Grays per year expected • FGC designed to be as tolerant as possible to radiation, within budget • Time between crashes estimated to be1-4 weeks for 750 systems • Many crashes will hopefully be reset transparently AB-PO-CC

  11. COD transfer function • Not tested • String2 now shutdown so no easy way to test in the near term • Perhaps parasitic tests can be done with magnet test benches next year • Theoretical performance can be estimated given circuit and converter characteristics • Small signal bandwidth will be a few Hz AB-PO-CC

  12. Multipole correctors? • Different Gateways to the CODs • Identical software everywhere, so all power converters can be controlled in real-time, though only correctors are expected to use the facility • Gateway layer will be invisible to application – it will simply see a set of controllable devices AB-PO-CC

  13. Thanks to AB-PO-CC and AB-CO • Any questions? AB-PO-CC

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