18. June 2003 EPICS WS

Control of Digital Power Supplies

Andreas LüdekeSwiss Light Source / PSI

20 May 2003EPICS Collaboration Meeting

18. June 2003 EPICS WS

PSI Digital Power Supplies

ADC/DACCard

DSPController

DCCT

0..6Slaves

Magnet

PWMSignal

Fast Optical Link(5 MHz)

DIO U1..4

I

PowerConverter

Master

Optical Trigger

18. June 2003 EPICS WS

Why use Digital Power Supplies?

• Single source of drifts: ADC voltage reference– All PS at the SLS proved to have excellent stability

• Flexibility of the power supplies– Regulation loop can be adapted to load– Easy to add new power supply features on DSP

• Good reproducibility, reliability• PWM is digital, modern DCCT will be digital• Why not?

18. June 2003 EPICS WS

Hardware Overview

Linux PCConsoles

IOC EVRCarrier

IP IP IP IP OrbitDSP

Timing

Trans.Mod.VME T.Mod

Power SupplyController

Parallel fast access (10k frames per sec)

• IOC IP• DSP IP• …

18. June 2003 EPICS WS

Power Supply Hardware

• DSP Controller Card– Euro card size– Shark DSP– Shark links on backplane

• ADC/DAC card– 2 ADC, 16 Bit, 50 kHz– 4 ADC, 12 Bit– 2 DAC for debugging

18. June 2003 EPICS WS

Fast and precise ADC

0 200 400 600 800 1000 1200 1400 1600 1800 20004.7888

4.7889

4.789

4.7891

4.7892

4.7893

4.7894

4.7895

- 10 µV

- 10 µV

+ 20 µV

- 40 µV

33 min t [s]

UADC

[V]

Umax

Umin

1 kHzFilter

10 µV 1 ppm 20th Bit

600 µV

18. June 2003 EPICS WS

VME Hardware

Industry Pack Carrier VME64x 4 slot boards“off-the-shelf”:• Greenspring Vipc664• Hytec 8002

VME64x Transition modulefor 8 power supplies

Industry Pack Module for 2 power supplies

18. June 2003 EPICS WS

DSP Software

• Local intelligence:– 50 kHz pulse width modulation loop– Sophisticated alarms, like change in load resistance– Triggered current waveform (DSP ramp)

• Scaleable, arbitrary waveform

• 16000 times 80 µsec steps > 1 second waveform

• The same DSP program for all PS– Locally stored parameter settings for each PS

18. June 2003 EPICS WS

EPICS device/driver

• Carrier board independent by use of drvIpac• Read and write 256 power supply registers• DSP waveform and program downloads• Softramps: synchronised current waveforms

– Arbitrary clock rate (<1kHz) for 8000 setpoints– Synchronised by timing system

• Diagnostic records– Statistics of optical fibre link and IP failures

18. June 2003 EPICS WS

EPICS database

• One template for 500 power supplies• Each power supply supports

– Download and save of DSP programs, parameter sets, DSP ID– current waveform: download, scaling, offset, length, …– reading max. and min. current from PS– reading actual magnet resistance from controller– ...

• Magnet cycling configurable for each PS• Detailed fault diagnostic for PS, link and driver

18. June 2003 EPICS WS

Software Management

• DSP software is documented by Excel sheets– Script transforms sheets into a C include file– Easy upgrade of the driver for new PS functions

• Identical DSP and EPICS software for all PS– Configuration by parameter set

18. June 2003 EPICS WS

Outlook

• PSI type digital PS are “en vogue”– Each manufacturer can get a PSI licence

– Diamond will use exclusively digital PS for magnets

– Soleil is evaluating the PSI digital PS• Industry Pack module can be used on CPCI

• Driver source can be reused for Tango

• Customized DSP programs – For specific application

– To drive several PS with one DSP card