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

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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 3050ms. 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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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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Parameters of the magnet power supplies
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Hardware Architecture
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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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BNL-designed Power Supply Controller/Interface
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System Configuration

• PSC in VME crate with FEC. PSI in the power
  supply. One PSC can control 6 PSIs.
• Connection between PSC and PSIa 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 PSIs 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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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. Dont 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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PSC
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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. gt60Hz It can show the ripple of
  power supply.

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PSI
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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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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

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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.
• readbackbipolar
• Current setpoint - The analog voltage from the
  PSIs 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 ErrorA voltage representing the current
  error, amplified within the power supply by a
  factor of 50.

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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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PSI(Cont.)

• Status16bit
• 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 its set limit.
• OVERCURRENT the power supply output current has
  exceeded its set limit

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PSI(Cont.)

• Status16bit
• OUT OF REGULATION
• FAN FAULT
• OVERTEMP
• WATER FLOW
• WATER MAT
• SECURITY INTERLOCK
• GROUND FAULT
• RIPPLE FAULT
• PHASE FAULT

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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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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 (x8x7x5x4x1
  generating polynomial, excluding start and stop
  bits)
• 2 stop bits ones
•  43 bits total

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Communication (Cont.)

• SNS Power Supply Interface Timing

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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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The PSI SystemThe Test Configuration
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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.

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Pricing

• Vendor Apogee Labs Inc.

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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 SNSs.
• SNS use regulators packaged in a VME crate (bulk
  power supply)
• choose VME IP modules for small power supplies.

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Thanks!