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Control of Digital Power Supplies. Andreas L ü deke Swiss Light Source / PSI 20 May 2003 EPICS Collaboration Meeting. PSI Digital Power Supplies. Master. Fast Optical Link (5 MHz). DSP Controller. ADC/DAC Card. Optical Trigger. 0..6 Slaves. PWM Signal. I. DIO. U 1..4. DCCT.
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Control of Digital Power Supplies Andreas Lüdeke Swiss Light Source / PSI 20 May 2003 EPICS Collaboration Meeting
PSI Digital Power Supplies Master Fast Optical Link (5 MHz) DSP Controller ADC/DAC Card Optical Trigger 0..6 Slaves PWM Signal I DIO U1..4 DCCT Magnet Power Converter
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?
Hardware Overview • Parallel fast access • (10k frames per sec) • IOC IP • DSP IP • … Power Supply Controller VME Trans.Mod. T.Mod Orbit DSP IP IP IP IP Linux PC Consoles IOC Carrier EVR Timing
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
Fast and precise ADC UADC [V] 10 µV 1 ppm 20th Bit Umax 4.7895 4.7894 - 10 µV + 20 µV 4.7893 1 kHz Filter 600 µV 4.7892 - 10 µV - 40 µV 4.7891 4.789 Umin 4.7889 4.7888 0 200 400 600 800 1000 1200 1400 1600 1800 2000 33 min t [s]
VME Hardware • Industry Pack Carrier • VME64x 4 slot boards • “off-the-shelf”: • Greenspring • Vipc664 • Hytec 8002 Industry Pack Module for 2 power supplies VME64x Transition module for 8 power supplies
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
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
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
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
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