• C. Kondo, K. Shirasawa
  JASRI/SPring-8, Hyogo-ken
• T. Inagaki, T. Sakurai, T. Shintake
  RIKEN/SPring-8, Hyogo

Low electro-magnetic noise interference (EMI) is required to the klystron modulator power supply for XFEL/SPring-8 project in order to realize the highly stable beam operation with aid of various feedback loops using high-performance beam monitors. The dominant noise source is the thyratron switching noise, associated with its rapid voltage swing of 50 kV maximum. To suppress the noise leakage, special care was taken to the enclosure design of klystron modulator, i.e., using thick steel plates a monocoque enclosure was fabricated, in which all of the high power circuits was installed. The rapid image current flows on the inner surface, thus EMI was minimized. A special co-axial feed-though was developed for filtering the conducted noise on power line for thyratron and klystron heaters. In this presentation, we will report the details of the devices and the results of the noise suppression.

• T. Ozaki, A. Akiyama, K. Harada, T. Kasuga, Y. Kobayashi, T. Miyajima, S. Nagahashi, T.T. Nakamura, M. Ono, T. Sueno
  KEK, Ibaraki

At PF-AR, a bending magnet power supply was updated in 2007. The converter works in the 3 pulsed PWM. A trouble caused by higher harmonics above 40th had occurred. We manufactured filters and installed in 6.6kV ac lines in 2008. Furthermore, a QF magnet power supply was updated in 2009. This paper reports on the update of PF-AR main magnet power supplies.

• H. Sato, t.s. Shintomi
  KEK, Ibaraki
• T. Ise, Y. Miura
  Osaka University, Graduate School of Engineering, Osaka
• S. Nomura, R. Shimada
  RLNR, Tokyo

Magnets of the synchrotron accelerator which extracts the accelerated beams are excited by pulse operation power supply, and then the load fluctuation should be a severe problem. An energy storage system, such as SMES, fly-wheel generator so far, will be required for compensating the pulse electric power, and reducing the disturbances of the connected power line. The system is also expected to protect the instantaneous voltage drop and contributes the reliability of the storage ring. Present status of R & D and the features for the energy storage systems are discussed. The application of the energy storage systems to synchrotrons for the medical use is described. The compensation of the typical pulse electric power of the synchrotron for the cancer therapy is studied.

• H. Someya, S. Igarashi
  KEK, Ibaraki
• S. Nakamura
  J-PARC, KEK & JAEA, Ibaraki-ken

The power supply current ripple of the quadrupole magnets of the J-PARC main ring has been measured to be the order of 10^-4. The magnetic field of the quadrupole magnets has been measured and the ripple frequency distribution of each magnet was observed to be depending on where the magnet is in the magnet chain. A transmission line model for the cable and magnets was able to explain the distribution. The field ripple made by the common mode current ripple was reduced by changing the magnet cabling to be symmetrical with respect to the N and S poles of the quadrupole magnets. The common mode ripple was drastically reduced. The normal mode ripple of 600, 1200 and 1800 Hz however remained. The field ripple was further reduced using resistors those are connected in parallel to the magnet coils and bypass the current ripple. It was effective to the higher frequency ripple of 1200 and 1800 Hz and the effect was in a good agreement with an electric circuit simulation program LTspice.

• Y. Watanabe
  JAEA, Ibaraki-ken

In J-PARC RCS, horizontal closed orbit distortion (COD) which is ±2 or 3mm in amplitude was observed all over the ring. Main component of the horizontal COD is 1kHz, phase variation period about 140 seconds. This paper demonstrates phase variation of the 1kHz horizontal COD caused by switching ripple from dipole magnet power supply. To suppress the phase variation of the horizontal COD, switching timing of the dipole magnet power supply was synchronized J-PARC timing system.

• H. Toki, K. Sato
  RCNP, Osaka

The ordinary electric circuits produce and receive electromagnetic noise. The noise is a problem for stable operation of synchrotron accelerators. We do not know the origin of the noise generation due to the lack of electric circuit theory, which takes into account the noise sources. The proper treatment of electric circuit together with noise requires a proper knowledge of multiconductor transmission-line theory. We have developed a new multiconductor transmission-line theory in which we are able to describe the performance of multiconductor transmission-line system*. In this theory, it is essential to use the coefficients of potential instead of capacities and the introduction of the normal and common modes. After understanding the multiconductor transmission-line theory, we propose the introduction of the middle line (three lines) and symmetric arrangements of electric loads**. The use of this concept made the J-PARC MR successful in operation.

* H. Toki and K. Sato, J. Phys. Soc. Jpn 78 (2009) 094201.
** K. Sato and H. Toki, Nucl. Inst. Methods A565 (2006) 351.

• S.-C. Kim, K.R. Kim, S.H. Nam, C.D. Park, Y.G. Son, C.W. Sung
  PAL, Pohang, Kyungbuk

Lattice of the Storage Ring (SR) is changed from TDB to DBA, and beam energy is enhanced from 2.5 GeV to 3.0 GeV at the Pohang Light Source upgrade (PLS-II). Therefore all magnet specification and number have to change compare with exist PLS SR. At the PLS-II, Magnet Power Supplies (MPS) must be re-designed according to magnet specification of the PLS-II. Newly development MPSs are adopted switching type power conversion technology. High current unipolar MPSs are parallel operation type of unit module buck type power supply, and low current bipolar MPSs are H-bridge type. All MPSs are performed ± 10 ppm output current stability and adopted full digital controller. In this paper, we report on the development and characteristics of the MPS for PLS-II SR.

• M. Pont, D. Alloza, R. Petrocelli, D. Yepez
  CELLS-ALBA Synchrotron, Cerdanyola del Vallès
• R. Camell, G. Gross, M. Teixido
  CITCEA-UPC, Barcelona

ALBA is a 3 GeV third generation synchrotron light source under construction in Spain. The design and performance of the ALBA Storage Ring Power Converters will be described. A total of 122 power converters are required: 1 for the dipoles (all connected in series), 112 for the quadrupoles (each magnets with its own power supply) and 9 for the sextupoles (each family connected in series). All converters are switched mode with full digital regulation and a common control interface. The paper will describe the performance of the power converters and compare it with the design specifications.

• M. Pont, D. Alloza, R. Petrocelli, D. Yepez
  CELLS-ALBA Synchrotron, Cerdanyola del Vallès
• R. Camell, G. Gross, M. Teixido
  CITCEA-UPC, Barcelona

ALBA is a 3 GeV third generation synchrotron light source under construction in Spain. The injection system is composed of a 100 MeV Linac as pre-injector followed by a full energy booster synchrotron. The booster requires AC power converters operating at 3.125 Hz with a sinusoidal current waveform. All converters are switched mode with full digital regulation and a common control interface. The design specifications have been demonstrated and early tests on the Booster commissioning with beam will be presented

• H. Thiesen, M.C. Bastos, G. Hudson, Q. King, V. Montabonnet, D. Nisbet, S.T. Page
  CERN, Geneva

The LHC was restarted on the 20th of November 2009 after 14 months of shutdown. The machine is composed of 8 powering sectors, each containing a main dipole circuit and two main quadrupole circuits. Each of these main circuits is entirely independent. To operate the LHC, the magnetic fields in the main magnets must be controlled with unprecedented accuracy. Indeed, the current in each power converter must be controlled with an accuracy of a few ppm (parts per million of nominal current) and the currents must be perfectly synchronised between sectors. To achieve the performance required of the LHC power converters, many challenges have been resolved. These include: measuring the power converter currents with an extreme absolute precision, control of these currents without tracking error or overshoot, perfect synchronisation of the current references sent to the power converters of the 24 main circuits. This paper details how these various problems have been resolved to obtain the performance required. Many experimental results are included, in particular the results of the tracking tests performed with the main circuits of the LHC.

• M. Emmenegger, H. Jaeckle, R. Künzi, S. Richner
  PSI, Villigen

In accelerator applications, high precision high speed power supplies (PSs) for magnets are needed to guarantee the high beam quality. These PSs are the main purpose of the presented second generation of a Digital Power Electronic Control System (DPC) which has been designed and successfully applied at the Paul Scherrer Institute PSI. The main components of the DPC are the controller board (DPC_CC) and the high precision analogue to digital converter board (DPC_AD). Compared to the first generation the properties such as precision, acquisition rate, processing power and functionality have been improved considerably. This allows faster control cycles and/or more complex control algorithms. The controller board now features 12 standard precision (16 bit) ADC channels and allows the simultaneous control of multiple power supplies. High precision requirements are met by adding the DPC_AD to the system. In conclusion, the modular and flexible design allows well-matched solutions for the typically heterogeneous accelerator power supplies.

• Y.-H. Liu, J.-C. Chang, C.-Y. Liu
  NSRRC, Hsinchu

The purpose of this paper is to estimate the conductive Electromagnetic Interference (EMI) from magnet power supply in NSRRC. A LISN system was conducted to measure the EMI spectrum of power supply. The different frequency range of conductive EMI was measured. For the future TPS(Taiwan Photon Source) power supply design, the EMI signals must be lower than TLS kicker. Therefore reducing and eliminating the interference of electromagnetic waves will be a very important issue. A filter and shielding method were used to test the effects of reducing EMI. The EMI prevention scheme will be used in the future.

• K.-B. Liu, K.T. Hsu, Y.D. Li, B.S. Wang
  NSRRC, Hsinchu
• J.C. Hsu
  CMS/ITRI, Hsinchu

Based on the requirement of beam stability for the third-generation synchrotron radiation light source is more stringent, lower ripple and higher bandwidth of output current of corrector magnet power converters should be developed to implement the closed orbit correction of Taiwan Photo Source (TPS). The ±10A/±50V corrector magnet power converter uses a full bridge configuration, the switching frequency of power MOSFET is 40 kHz, in that each bridge leg has its own independent PWM controller and the output current bandwidth is 1 kHz when connected with the corrector magnet load. Using a DCCT as the current feedback component the output current ripple of this converter could be lower than 5 ppm. In this paper, we will describe the hardware structure and control method of the corrector magnet power converter and the test results will be demonstrated.

• C.-Y. Liu, Y.D. Li
  NSRRC, Hsinchu

We design and implement a power convert to supply dc power bus for the MCOR30 correction supply. The dc power supply's characteristics were variable frequency at heavy and medium/light load. These characteristics matched with the correction supply working requirement. The dc power bus has a relaxation oscillator generating a symmetrical triangular waveform, which MOSFET's switching is locked to. The frequency of this waveform is related to a current that will be modulated by feedback circuitry. As a result, the tank circuit driven by half-bridge will be stimulated at a frequency dictated by the feedback loop to keep the output voltage regulated, thus exploiting its frequency-dependent transfer characteristics. The high performance characteristics of the resonant dc power bus are illustrated in this paper.

• K.-B. Liu, K.T. Hsu, Y.D. Li, B.S. Wang
  NSRRC, Hsinchu

The Taiwan Photon Source (TPS), a third-generation synchrotron radiation light source, should be installed with 1032 sets of magnet power supplies for the storage ring and 152 sets for the injector. All of the power supplies are preferred in PWM switched mode with IGBT or MOSFET. A high precision DC power supply for 48 dipoles of the storage ring; there are 240 quadrupole magnets and 168 sextupole magnets in storage ring, the main winding of quadrupole and 168 sextupole magnets are powered by individual power supplies. In the booster ring, one set of dynamic power supply for the dipole magnets and four sets for quadrupole magnets run at the biased 3Hz quasi sinusoidal wave. There are several hundred corrector (fast and slow) magnets and skew quadrupole magnets in storage ring and injector are powered by the same bipolar power converters.

• B.S. Wang, K.T. Hsu, Y.D. Li, K.-B. Lin, K.-B. Liu
  NSRRC, Hsinchu

This paper presents an implementation of a precision corrector magnet power converter using the digitally controlled pulse width modulation method. The output current precision of this ±10A/±50V corrector magnet power converter is within ±10ppm. The digital control circuit of the power converter is implemented with using a high speed ADS8382 18-bits analog-to-digital converter and a TMS320F28335 digital signal processor. The converter uses a full bridge configuration, the switching frequency of power MOSFET is 40 kHz and the control resolution is 17-bits. Using a DCCT as the current feedback component the output current ripple of this converter could be lower than 5 ppm that is beyond the requirement of TLS corrector power converter and suitable to be used in TPS.

• G. Feng, B. Deriy, T. Fors, J. Wang
  ANL, Argonne

The DC/DC converters in the Advanced Photon Source storage ring are more than 15 years old, and an upgrade is underway to resolve the aging and obsolescence issues. In the upgrade, an 18-bit resolution for current regulation is desired. This paper describes a digital control system to achieve this goal. The system uses a serializer chip, TI TLK2541, combined with a ∑-Δ modulator to realize a 21-bit digital pulse width modulation (DPWM). Analog and digital filters are implemented to block the ripple currents and to reduce the EMI noises. Deployed with filter circuits, a digital compensator has been designed to meet the requirements of output current regulation. Furthermore, a voltage feed forward is employed to compensate for input bus voltage variations. A prototype digital controller using a field-programmable-gate-array development board has been developed. The resolution of the current regulation, and the effect of noises into the digital controlled power converter system have been tested and analyzed.