SNS Power Supply Control Sheng Peng ICS

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

Overview l Power supplies are from different vendors » IE power, Danfysik, Alpha … l Power supplies have different capability » » » » » l +/- 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 ICS – Software Engineering Group 2

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

Power Supplies in SNS ICS – Software Engineering Group 4

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

PSC/PSI Software ICS – Software Engineering Group 6

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

PSI ICS – Software Engineering Group 8

PSC/PSI in SNS l l PSC/PSI is the SNS standard interface to every power supply PSI (Power Supply Interface) » » » » l 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 100 ms 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 128 K circular buffer per channel to save 5458 samples Software or hardware triggered read/write up to 5 KHz Burst read up to 10 K samples/second (BNL is upgrading it to 100 K) ICS – Software Engineering Group 9

Communication Protocol/Real-time performance l CPU PSC » » l 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 » 5 MHz carrier, upgradeable to 50 MHz » Each frame consist of 1 start bit, 1 byte frame ID, 3 bytes data, 1 byte CRC and 2 stop bits. So 43 bits(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 10

Portable Power Supply Test Stand ICS – Software Engineering Group 11

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

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

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

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

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 $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 ICS – Software Engineering Group 16

Status l In use at NSRL and SNS » DC power supplies 100 ppm accuracy » 60 Hz 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 17

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 ICS – Software Engineering Group 18