1. Power Supply Control for BEPCII
Chunhong Wang
Control Group
Accelerator Center of IHEP
20 Aug., 2002
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2. Outline BEPC Power Supply Control System Overview
BEPCII Power Supply Control Requirements
Hardware Architecture
PSC/PSI System Configuration
PSC/PSI Testing Configuration
PSC/PSI pricing
Conclusion
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3. BEPC Power Supply Control
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4. BEPCII Power Supply Control Requirements
About 400 magnet power supplies distributed in the double ring and transport line.
Turning on/off all magnet power supplies locally and remotely.
Monitoring current and status of the power supplies, such as the status of on/off, local/remote, normal/alarm, etc.
Setting values
Direct setting mode
Synchronized ramp mode: time interval between two setpoints 30~50ms. Total ramp time: 3min.
Standardization mode
Knobs - adjusting individual power supply.
Interlock system for protection of magnets and power supplies.
Saving the real-time and historical data in the database for later analysis.
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5. Requirements(Cont.) Interfaces
Simple.
Easy to install and maintain.
Isolation between the control system and the power supplies.
Preserve our investment in the hardware, the CAMAC in the transport line will remain.
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6. Parameters of the magnet power supplies
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7. Hardware Architecture
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8. Front-end
IOC: 21slot VME64x crate with Motorola MVME2431 PowerPC CPU. VxWorks kernel.
Power Supply I/O:
For high precision PS, use a BNL-designed Power Supply Controller/Interface technology.
For corrector PS, use direct VME I/O IP module.
For transport line PS, VME-CAMAC interface and CAMAC I/O module.
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9. BNL-designed Power Supply Controller/Interface
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10. System Configuration
PSC in VME crate with FEC. PSI in the power supply. One PSC can control 6 PSI’s.
Connection between PSC and PSI：a pair of fibers.
Data transmission speed up to 5 Mb/s.
Up to 500 Meter Distance.
Provide isolation between the control system and power supply.
Outgoing messages from PSC to the PSI’s can be initiated by:
VME commands
RS-232 commands
Event timing signals (Read and Write pulses)
Burst mode (automatically performs multiple writes/reads once started)
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11. System Features Performance for both operations and diagnostics:
Burst mode. To determine ripple and other higher frequency components at up to 10KHz.
Circular buffer: to store about 5,000 sets of historical data.
Timed readings and setpoints: by either hardware or software triggers.
Data access by VME or serial port: allow power supply testing with or without a complete control system.
Interface simple:
No isolation circuitry required. Don’t need opto-isolators and isolation amplifiers
Installation simple.
The connection between the PSI and power supply: two cables
1 for analog signals, 1 for the digital signals
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12. PSC
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13. PSC a VME module. RS-232 serial port for test purposes.
6 fiber connectors 1 send, 1 receive pair per channel.
2 Event Link decoder Inputs, 1 for Write, 1 for Read
An outgoing message can be initiated either by the VME bus or by the external read or write pulses.
Operation mode:
Normal mode: 60Hz synchronous with the beam
Burst mode: to gather data with finer time resolution. >60Hz It can show the ripple of power supply.
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14. PSI
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15. PSI PSI 4 A/Ds、1D/A、command bits、status bits。
Analog to Digital (ADC) converter:
Resolution-16 bits
Accuracy-15bits
Conversion time-20μSec
Analog input-Bipolar ±10 Volts
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16. PSI (Cont.) Digital to Analog(DAC)Converter: Digital Outputs:
Resolution-16 bits
Accuracy-15 bits
Conversion time-20μSec
Analog output-Bipolar ±10 Volts
Digital Outputs:
Level-15 Volt CMOS levels
Drive capability-Sink or source at least 1mA
Digital Inputs:
Drive requirements-Sink or source no more than 1mA
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17. PSI(Cont.) All signals for the power supply：
Timing: timed setpoints and readbacks.
Setpoint: D/A 16 bit resolution with 15bit stability。Most stability 1x10-4. unipolar or bipolar.
readback：bipolar
Current setpoint - The analog voltage from the PSI’s D/A is converted back as a measure of both the D/A and the A/D. A voltage of 10V will represent full scale current.
Measured current - A voltage representing the current as measured by DCCT. 10V will represent full scale current.
Measured Voltage – A voltage representing the power supply voltage. It includes both magnet and cable voltage drops. 10V will represent full scale voltage.
Current Error：A voltage representing the current error, amplified within the power supply by a factor of 50.
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18. PSI(Cont.) Commands: 8bit。 ON – Turns the power supply on.
OFF- Turns the power supply off.
STANDY- Turns on control power in the supply, but does not energize the magnet load. In some supplies, this also resets faults.
RESET-Resets faults in supplies that require a separate line.
NEGATIVE POLARITY-Reserses polarity of current in the magnet to what is defined as
Three unallocated command bits。
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19. PSI(Cont.)
Status:16bit
ON- the power supply on and delivering power to the magnet load.
OFF- the control power to the power supply off, but AC power on.
STANDBY-control power to the power supply on, but no power is being sent to the magenet load.
NEGATIVE-the power supply is in the reverse polarity
FAULT SUMMARY: fault,shutdown the power.
OVERVOLTAGE – the power supply output voltag has exceeded it’s set limit.
OVERCURRENT – the power supply output current has exceeded it’s set limit
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20. PSI(Cont.) Status:16bit OUT OF REGULATION FAN FAULT OVERTEMP
WATER FLOW
WATER MAT
SECURITY INTERLOCK
GROUND FAULT
RIPPLE FAULT
PHASE FAULT
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21. Communication between PSC and PSI
A message from the PSI to the PSC consists of several frames. Each frame has a start bit, ID, Data, CRC and end bits.
Messages Sent From The PSC To The PSI
a) Write a new setpoint (16 bits of data to DAC)
b) Write a new command (15 bits of data to digital output port)
c) Read Requests (readback command & setpoint data or readback status and 4 analog inputs
d) Read status and four analog channels
Messages Sent From The PSI To The PSC
Read Response
Write Response
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22. Communication(Cont.) A frame consists of the following:
1 start bit “0”
8 bit frame ID
16 bit data field twos compliment binary
8 bits unused “0”
8 bit crc error check (x8+x7+x5+x4+x+1 generating polynomial, excluding start and stop bits)
2 stop bits ones
 43 bits total
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23. Communication (Cont.)
SNS Power Supply Interface Timing
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24. Maximum communication time
One frame is sent from the PSC to the PSI: 8.6µSec.
The analog to digital conversion is initiated on receipt of frame from the PSC: 20 µSec.
A reply of six frames and sent from the PSI to the PSC: 8.6x6 µSec.
The time to send the read request: 10 µSec.
The time to process the received data: 5 µSec.
Total is 95.2 µSec.
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25. The PSI System The Test Configuration
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26. The PSI System The Test Configuration
A laptop connected to RS-232 serial port.
Labview software programming.
Reading and writing at 15Hz.
Check accuracy and linearity of DAC and ADCs and temperature stability of PSI.
Test power supplies.
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27. Pricing
Vendor: Apogee Labs Inc.
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28. Conclusion The performance and reliability have been tested.
Vxworks/Epics software drivers for the PSC available.
PSC/PSI meet the requirements of large power supply control except for B and SCQ power supplies.
Change DAC and ADC resolution for B and SCQ power supplies.
Best solution for large power supplies.
A good system integration compared to other methods.
Save time and reduce work.
Small power supplies are different from SNS’s.
SNS use regulators packaged in a VME crate (bulk power supply)
choose VME IP modules for small power supplies.
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29. Thanks!
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