NUMI

Power Supply Regulation

WBS 1.1.3 Power Supply System

Level 3 Manager

Nancy Grossman

FNAL

June 28, 2001

NUMI

Internal NuMI ReviewJune 28, 2001

Power Supply RegulationPage 2Overview of Regulation Needs

7 Magnet Strings with regulation requirements ranging from 55 ppm to 400 ppm. 55 ppm means +/- 55 ppm relative to the flattop operating current (RMS). V105 string requirement is 60 ppm, close to the tightest requirement. Discussion will center around simulations of the V105 string.

3 sources of current variation for magnet strings: 720 Hz power supply voltage ripple being applied to the magnets. Line voltage changes. Load changes.

Simulations of a particular power supply (or series of power supplies) can be used to see the effects of these changes on the resulting flattop current.

NUMI

Internal NuMI ReviewJune 28, 2001

Power Supply RegulationPage 3720 Hz Ripple Effect

720 Hz line ripple effect on the PS currents is shown in the table below. Not acceptable Need filters for each string Refurbish existing filters

Have costed 3, have claimed 7 for NuMI.Estimated cost to remove, refurbish and install: ~$10k/string (extra $40K)

String

Maximum Current of

PS

Peak Current (amps)

Corresponding target RMS in

microns

Allowed Instability in

ppm

Variation due to 720 Hz in ppm with no

Filters

Variation due to 720 Hz in ppm with Filters

Lam60 2500 1445 240 200 298 21V100 5000 2786 200 400 660 25HV101 2500 1449 250 65 214 14V104 2500 1449 75 200 248 21V105 5000 4254 170 60 254 7V109 1250 880 250 200 216 23V110 2500 1210 250 55 207 17

NUMI

Internal NuMI ReviewJune 28, 2001

Power Supply RegulationPage 4Line Voltage and Load Changes

Simulations were run for the NuMI V105 string, assuming a constant reference voltage. 5% change in line voltage was easily corrected for at the level of ~25 ppm

with standard voltage regulation. (most variation one would expect) 5% load change (resistance) gave a 240 ppm current variation. Corresponds to about a 100 C change in the copper in the magnet or the LCW changing 150C Other magnet strings would have similar results most likely. Not acceptable. Need additional regulation.

HOLEC transductor ($5K/string) Special FNAL regulation electronics ($5K/string) Both are designed and installed in the Main Injector This combination of electronics would give another factor of 2 120 ppm

NUMI

Internal NuMI ReviewJune 28, 2001

Power Supply RegulationPage 5Line Voltage and Load Changes

Three strings are still above the required specifications.

So now what?

String

Maximum Current of

PS

Peak Current (amps)

Corresponding target RMS in

microns

Allowed Instability in

ppm

Instability in ppm with Filters & HOLEC & Special Electronics

Extra Factor Needed

(reg/spec)Lam60 2500 1445 240 200 173 0.87V100 5000 2786 200 400 179 0.45HV101 2500 1449 250 65 173 2.65V104 2500 1449 75 200 173 0.86V105 5000 4254 170 60 118 1.96V109 1250 880 250 200 142 0.71V110 2500 1210 250 55 207 3.76

NUMI

Internal NuMI ReviewJune 28, 2001

Power Supply RegulationPage 6Additional Factor of 2 - 4

Bandwidth Each string will be tuned for maximum bandwidth. 20 Hz is assumed in the previous calculations. 40 Hz is frequently achieved (but not guaranteed).

Gives a factor of 2 in current stability.

Auto-tune Load changes are typically slow changes and thus Auto-tune can correct for

these. One could then argue why do you need the extra power supply regulation too?

Auto-tune does not always work.Needs beam and working beam position monitors to work.Assumes next beam pulse like the previous one.

Experience at FNAL where significant beam control is needed says do both. Since the power supply regulation is also driven some by groundwater

concerns, we want something that is always working.

NUMI

Internal NuMI ReviewJune 28, 2001

Power Supply RegulationPage 7Other Primary Beam Power Supplies

Quadropole power supplies (20 KW PEI’s): Standard regulation is at +/- 0.05% of the maximum current (100 or 200 amps)

Corresponds to up to +/-0.44% variation in operating current.

Believed to be sufficient.

Main Injector Trim Magnet power supplies: Standard regulation is at +/- 0.1% of the maximum current (15 amps) Believed to be sufficient.

NUMI

Internal NuMI ReviewJune 28, 2001

Power Supply RegulationPage 8Summary

NuMI power supply regulation levels will be achieved by: Filters on all 7 strings. HOLEC and FNAL Electronics on all 7 strings. Auto-tune. Tuning for maximum bandwidth.

Cost increase to NuMI: ~$40k for 4 additional filters (refurbished) ~$70k for 7 sets of HOLEC/regulation electronics (one for each string)

Other slightly less expensive (and perhaps more effective) options may be designed by Fermilab before NuMI runs, in which case we would certainly use them.

Studies in the Main Injector P1 line will also help us to better define the level of regulation one obtains with a HOLEC transductor and special regulation electronics.