Ring magnet system—Power supplies—
T. OkiT. Adachi
T. Kawamoto
S. Nakamura

21th KEKB Accelerator Review Committee

List of Magnet power supplies• Newly fabricated or old power supplies for Main Ring
Output power

Newly
Reused PS
fabricated #( overhauled)PS

0.95 MW20

Main dipoles

0.4-1 MW90Wigglers

0.1-0.5 MW

018#

Main quadrupoles

2-105 kW92

335#

Bend./Quad./Sext.

0.3-2.4 kW

138

1681

Steering magnets/
corrector coils

Total

359

2034

・ Newly fabricated or to be fabricated (*) QCS power supplies2kA, 15V

2+6*0

QCS Main quads.

<500 A, 20 V

3*0

QCS Solenoids±70A, ±10V

450

QCS correction coils

Start up: system check and full power load test
• Full-scale start-up tasks such as network test, interlock systemtest, full power load test, cable connection check to avoid
abnormal heating, polarity check, magnet standardization test andso on were completed before Feb.8 beam injection to the MR.

Test example 1/2 —switching noise• Old medium-class power supplies were overhauled. Replacementof chemical capacitors, AC-DC converters, circuit breakers andIGBTs was performed.
Ceramic capacitors• In order to reduce switching noise,ceramic capacitors are added at theoutput terminal. Switching noise isreduced to 1/20.

W/O capacitor

W/ 1 μF capacitor

VPVP
0.1 V/div

5 V/div
VNVN
10 μs/div

10 μs/div

Test example 2/2 —ripples• Newly fabricated medium class power supplies were designed tobe lower current ripples. Histograms of current ripples arecompared with the results of old (overhauled) power supply.

#of PS’s#of PS’s

Overhauled 335 of old PS

Newly fabricated 92 of PS

1 ppm

0.6 ppm

5 ppm

0.2 ppm

50 Hz

First Commissioning in Phase 1• Magnet power supply system works well except for following
failures occurred up to now.
Failures in Large class PS# of event comment

AC input over current

3

AC distortion (RF system crowbar work)

AC input over current

6

AC distortion (VAR system# work in line facility)

AC input Stop, CB Fault

2

Earthquake

Failures in Medium class PS# of event comment

Thermostat

4

Thermal control equipment was repaired.

Over current (IGBT modules)

2Modules were replaced. Repaired.

Cable GND fault

1

The fault cable was disconnected.

Tracking error

1

Fault in the polarity inversion circuit. Repaired.

Failures in small class PS
DC-DC board failure
Output over voltage etc.

# of event comment
17Power supplies themselves were replaced.

#) Compensation system for a reactive power in the AC power distribution facility. AC line phase-advancing capacitor equipment was automatically controlled. However, unexpected operation occurredin early stage of Phase 1. Since capacitors has been manually operated, failures doesn't occur.

First Commissioning in Phase 1-cont.

standardization• How the system works well? Current stability ofMain dipole magnet power supply is comparedwith one of KEKB.
KEKB (1250 A, 770 V)
5 mA

SuperKEKB (860 A, 1100 V)
standardization

0.5 mA~20 ppm(p-p)/week

1.3 ppm(p-p)/week

1 week

1 weekTwo prompt contributions to Phase 1 commissioning
1. As Funakoshi-san and Sugimoto-san reported: in order tocompensate a leak field of a lambertson magnet, additional coilsof SX and skew Q magnet were wound/ applied for this purpose.
2. As Funakoshi-san and Suetsugu-san reported: Solenoid coils
were tentatively wound over LER vacuum chamber by vac. group,and small class power supplies also support to drive it.
Shift report(April. 8)

Y. Suetsugu (IPAC16)

Preparations for Phase 2: IP collision feedback system• SLAC Dithering coils for IP horizontal collision feedback systemwere installed.
• Power supplies were also installed, and cabling for the coils werecompleted. Magnetic polarity check was done.

Coil installation was performed
with U. Wienands, SLAC.

Preparations for Phase 2: QCS power supply system• Many works are in progress to be ready for the QCS operation,
which starts in Nov. 2016 for L-side or Feb. 2017 for R-side.
- Power supplies
Prototype power supply for both of main and corrector coils
was developed. Mass production and fabrication of antisolenoid PS’s has been carried out.
- Cabling
Cable laying work from PS building to IR was completed.
Work for the connection of the cables to PS’s or QCS is planedin this summer.
- Facility for power supply
AC power distribution board and water cooling system has
been designed. These will be ready by the end of this Oct.
- Interlock/monitor system
PLC system has been fabricated, and will be derived by theend of this July.

QCS cable laying work

Cables were laid from PS building…

and cable rack to the interaction region…

through vertical shafts…

Cables to beconnected
with QCS magnets

A full-scale prototype of QCS power supply
Aiming spec.
Rated output

DC 2 kA, 10 V

Current setting resolution< 0.1 ppm

Current stability< 2 ppm/8 hrs.

Current ripple (< 10kHz)< 1 ppm (rms)Current noise (> 10kHz)< 1 ppm (0-peak)(1) For low ripple and noise: Symmetric structure DCCTs on both output
terminals.
 Symmetric circuit structurewith respect to ground.
 Shielded high-frequency
transformer

Digital feedback control for QCS power supply(2) For high stability: Digital feedback with 24-bit control board
24-bit control board
Major setting
value (20 bits)+-

Minor setting
value (4 bits)
Two 20bit
DACs(AD5791)

DAC+++-

1/24

DAC

-

Analogcurrentcontrol
loop

Error

Digital feedback
loop

8.5-digit DMM
1/2Output
terminalNPDCCT(N)+1/2

DCCT(P)Temp. coefficients of the system• 0.125 ppm/K (AD5791 DAC with Buffer amps.)• 0.3 ppm/K (Keithley 2002)• 1.5 ppm/K (TOPACC) (or 0.5 ppm/K (TOPACC optional))--------Total: 1.925 ppm/K
Constant climate chamber keeps temp. within 0.2 deg.
→ 0.385 ppm for 0.2 deg

Test result of the digital feedback system
Output current measured by
DCCT (0.25 mA/div)• Performed by using a medium-class power supply (15 V, 500 A).
Digital feedback loop
well corrects DAC input
by 24bit resolution

1 hour
1.9 ppm

Test result of QCS prototype: 1.9 ppm (p-p)/8 hrs.
Ripple, noise, quench protection test, etc :OK.
→Mass production has been carried out.

8 hrs.

QCS corrector power supply
45 of QCS corrector power supplies was fabricated.
Rated output

DC ± 70 A, 10 V

Current setting resolution< 1 ppm

Current stability< 5 ppm/8 hrs.

Current ripple (< 10kHz)< 5 ppm (rms)Current noise (> 10kHz)< 5 ppm (0-peak)

Test results: Stability 2.1 ppm/24 hrs. with temp. coeff. of 0.6 ppm/℃
24 hrs.

12.34 ppm

20.5 ℃
Ripple, noise, quench protection test and so on: also OK.

Summary• Magnet power supply system was integrated and finished before
Phase 1. Where the full-scale start-up tasks were completed.
• In the full-scale load test, both the old and newly fabricatedmedium-class power supplies showed low ripple and low noisecharacteristic, successfully.
• Magnet power supply system has been worked well during Phase
1 commissioning except for several minor failures. The current
stability of main dipole power supply should be remarkably
mentioned.
• Preparations for Phase 2 have been in progress. Dithering coils for
the IP collision feedback system and power supplies have been
already installed.
• For the QCS system, many works are in progress to be ready for
the QCS operation, which starts in Nov. 2016 for L-side or Feb.
2017 for R-side.