ICS – Software Engineering Group 1 SNS Power Supply Control Sheng Peng

ICS – Software Engineering Group 2 Overview l Power supplies are from different vendors »IE power, Danfysik, Alpha … l 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, Volts »+20 Amps, +75 Volts »+40 Amps, +75 Volts »… l Uniform control interface for most of power supplies »SNS Power Supply Controller (PSC)/Power Supply Interface (PSI) »EPICS based software

ICS – Software Engineering Group 3 Revisons l PSC »6U single wide VME board for operation »1U rack mounted for PSI test and calibration »PSC based function generator (RHIC only) l 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)

ICS – Software Engineering Group 4 Power Supplies in SNS

ICS – Software Engineering Group 5 Automated Power Supply Test and Calibration

ICS – Software Engineering Group 6 PSC/PSI Software

ICS – Software Engineering Group 7 PSC/PSI Hardware PSI and VME with CPU and PSC PSC PSI CPU

ICS – Software Engineering Group 8 PSI

ICS – Software Engineering Group 9 PSC/PSI in SNS l PSC/PSI is the SNS standard interface to every power supply l 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 l 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)

ICS – Software Engineering Group 10 Communication Protocol/Real-time performance l 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 l 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

ICS – Software Engineering Group 11 Portable Power Supply Test Stand

ICS – Software Engineering Group 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.

ICS – Software Engineering Group 13 Electrical performance (Some test results) l Fiber interface provides the best electrical isolation l ADC Reading Accuracy

ICS – Software Engineering Group 14 Some Test Results l ADC Linearity Test »Approximately 1-bit (300uvolts) variation from –10v to +10v input.

ICS – Software Engineering Group 15 Some Test Results l ADC Temperature Stability 300uvolts = 1 bit Approximately ½ bit change with 10 degree F change in temp.

ICS – Software Engineering Group 16 Cost l There are two choice to get PSC/PSI »Buy as COTS from Apogee Labs »Get design then have a manufacturer to build it l 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 $ (~$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 + $ /6 = ~$1380/PS »If we build PSC too, the target cost should be ~$1150/PS

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

ICS – Software Engineering Group 18 Summary l PSC/PSI combination can be a cost-effective solution l H/W is proven reliable l H/W design is “open” l EPICS S/W is available l User community is growing