18. June 2003EPICS WS Control of Digital Power Supplies Andreas Lüdeke Swiss Light Source / PSI 20 May 2003 EPICS Collaboration Meeting

18. June 2003EPICS WS PSI Digital Power Supplies ADC/DAC Card DSP Controller DCCT 0..6 Slaves Magnet PWM Signal Fast Optical Link (5 MHz) DIO U 1..4 I Power Converter Master Optical Trigger

18. June 2003EPICS 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 2003EPICS WS Hardware Overview Linux PC Consoles IOCEVRCarrier IP Orbit DSP Timing Trans.Mod. VME T.Mod Power Supply Controller Parallel fast access (10k frames per sec) IOC  IP DSP  IP …

18. June 2003EPICS 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 2003EPICS WS Fast and precise ADC µV + 20 µV - 40 µV 33 min t [s] U ADC [V] Umax Umin 1 kHz Filter 10 µV  1 ppm  20 th Bit 600 µV

18. June 2003EPICS WS VME Hardware Industry Pack Carrier VME64x 4 slot boards “off-the-shelf”: Greenspring Vipc664 Hytec 8002 VME64x Transition module for 8 power supplies Industry Pack Module for 2 power supplies

18. June 2003EPICS 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 times 80 µsec steps  > 1 second waveform The same DSP program for all PS –Locally stored parameter settings for each PS

18. June 2003EPICS 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 2003EPICS 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 2003EPICS 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 2003EPICS 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