Power Supply Control for BEPCII

1. Power Supply Control for BEPCII Chunhong Wang Control Group Accelerator Center of IHEP 20 Aug., 2002

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

3. BEPC Power Supply Control

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.

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.

6. Parameters of the magnet power supplies

7. Hardware Architecture

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.

9. BNL-designed Power Supply Controller/Interface

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)

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

12. PSC

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.

14. PSI

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

16. PSI (Cont.) • Digital to Analog(DAC)Converter: • 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: • Level-15 Volt CMOS levels • Drive requirements-Sink or source no more than 1mA

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.

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。

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

20. PSI(Cont.) • Status:16bit • OUT OF REGULATION • FAN FAULT • OVERTEMP • WATER FLOW • WATER MAT • SECURITY INTERLOCK • GROUND FAULT • RIPPLE FAULT • PHASE FAULT

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

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

23. Communication (Cont.) • SNS Power Supply Interface Timing

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.

25. The PSI SystemThe Test Configuration

26. The PSI SystemThe 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.

27. Pricing • Vendor: Apogee Labs Inc.

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.

29. Thanks!