# Presentation: 419795

## Power Supply Control for  BEPCII 

- Chunhong Wang
- Control Group
- Accelerator Center of IHEP
- 20 Aug., 2002

## 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

## BEPC Power Supply Control

## 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.

## 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.

## Parameters of the magnet power supplies

## Hardware Architecture

## 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.

## BNL-designed Power Supply Controller/Interface

## 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)

## 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

## PSC

## 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.

## PSI

## 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

## 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

## 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.

## 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。

## 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

## PSI(Cont.)

- Status:16bit
- OUT OF REGULATION
- FAN FAULT
- OVERTEMP
- WATER FLOW
- WATER MAT
- SECURITY INTERLOCK
- GROUND FAULT
- RIPPLE FAULT
- PHASE FAULT

## 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

## 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

## Communication (Cont.)

- SNS Power Supply Interface Timing

## 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.

## The PSI SystemThe Test Configuration

## 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.

## Pricing

- Vendor: Apogee Labs Inc.

## 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.

## Thanks!