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SNS Power Supply Control

SNS Power Supply Control. Sheng Peng. Overview. Power supplies are from different vendors IE power, Danfysik, Alpha … Power supplies have different capability +/- 20 Amps, +/- 35 Volts stackable +525 Amps, +35 Volts +400 Amps, +20 Volts +375 Amps, +80 Volts +390 Amps, +24 Volts

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SNS Power Supply Control

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  1. SNS Power Supply Control Sheng Peng

  2. Overview • Power supplies are from different vendors • IE power, Danfysik, Alpha … • Power supplies have different capability • +/- 20 Amps, +/- 35 Volts stackable • +525 Amps, +35 Volts • +400 Amps, +20 Volts • +375 Amps, +80 Volts • +390 Amps, +24 Volts • +700 Amps, +18 Volts • +900 Amps, +51 Volts • +1300 Amps, +95 Volts • +1405 Amps, +390 Volts • +4000 Amps, +18 Volts • +6000 Amps, +440 Volts • +185 Amps, +27 Volts • +1400 Amps, +800 Volts • +2200 Amps, +33000 Volts • +20 Amps, +75 Volts • +40 Amps, +75 Volts • … • Uniform control interface for most of power supplies • SNS Power Supply Controller (PSC)/Power Supply Interface (PSI) • EPICS based software

  3. Revisons • PSC • 6U single wide VME board for operation • 1U rack mounted for PSI test and calibration • PSC based function generator (RHIC only) • PSI • 1U rack mounted for rack mounted/standalone power supply • 6U single wide VME board for VME-style power supply • “Higher speed less ADC” PSI (Under development in RHIC)

  4. Power Supplies in SNS

  5. Automated Power Supply Test and Calibration

  6. PSC/PSI Software

  7. PSI and VME with CPU and PSC PSI PSC CPU PSC/PSI Hardware

  8. PSI

  9. PSC/PSI in SNS • PSC/PSI is the SNS standard interface to every power supply • PSI (Power Supply Interface) • Installed with every power supply • One 16-bit DAC with jumper selectable Unipolar/Bipolar mode • Four 16-bit ADCs • Self calibration • 15 bits digital out with selectable static or 100ms pulse mode • 16 bits digital in • Fiber link to PSC, 9-pin analog connector/37 pin digital connector to power supply • PSC (Power Supply Controller) • Customized VME board with serial port available • Fiber link to PSI • Support 6 power supplies per board • 128K circular buffer per channel to save 5458 samples • Software or hardware triggered read/write up to 5KHz • Burst read up to 10K samples/second (BNL is upgrading it to 100K)

  10. Communication Protocol/Real-time performance • CPU  PSC • Communicate thru VME bus backplane • All registers are memory mapped • Large circular buffer holds read back • Typical VME access cycle is 0.5~1.0 µs/word • PSC  PSI • Multimode fiber with SC connector • 5MHz carrier, upgradeable to 50MHz • Each frame consist of 1 start bit, 1 byte frame ID, 3 bytes data, 1 byte CRC and 2 stop bits. So 43bits(8.6µs)/Frame in total. • Setpoint/command needs only 1 frame (plus 1 echo) • Readback needs 7 frames (1 request, 6 response) • Whole write action takes ~20µs (include DAC setup time) • Whole read action takes ~80µs

  11. Portable Power Supply Test Stand

  12. Long Term Reliability Test Stand Each VME Has 4 PSC’s Each Rack Has 24 PSI’s Running at up to 4000Hz for several months Many 10^12 messages without CRC or timeout errors.

  13. Electrical performance (Some test results) • Fiber interface provides the best electrical isolation • ADC Reading Accuracy

  14. Some Test Results • ADC Linearity Test • Approximately 1-bit (300uvolts) variation from –10v to +10v input.

  15. Some Test Results • ADC Temperature Stability 300uvolts = 1 bit Approximately ½ bit change with 10 degree F change in temp.

  16. Cost • There are two choice to get PSC/PSI • Buy as COTS from Apogee Labs • Get design then have a manufacturer to build it • PSI • RHIC built it recently with a small amount: $895 each • RHIC built revised PSC with a small amount: $1600 each • Apogee Labs ask for $2854.50 (~$2000 for BNL) per board with the order more than 100 boards • Assume we buy PSC from Apogee Labs and build PSI like RHIC did, the cost will be $895 + $2854.50/6 = ~$1380/PS • If we build PSC too, the target cost should be ~$1150/PS

  17. Status • In use at NSRL and SNS • DC power supplies 100ppm accuracy • 60Hz triggered read/write • Preliminary use at IHEP • planned for BEPC-II • Under evaluation for other BNL applications • Design owned by BNL • EPICS S/W freely available

  18. Summary • PSC/PSI combination can be a cost-effective solution • H/W is proven reliable • H/W design is “open” • EPICS S/W is available • User community is growing

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