Novel Topology for Four-Quadrant Converter

Particle accelerators, like the LHC (Large Hadron Collider), make use of true bipolar power converters to feed superconducting magnets. Moreover, the LHC imposes that most converters must be installed underground. This constraint leads to the necessity of a high efficiency and a reduced volume for all the power converters. In this paper, the authors present a novel four-quadrant topology composed by an association of a ZVS-inverter and a ZCS-rectifier. This DC-AC-DC converter is fully reversible and a soft-switching operation mode is achieved for all switches over the full operating range. After a thorough analysis of the prototype design [±600A, ±10V], simulation and experimental results confirm the general performance of this power structure

CERN Proton Synchrotron working point control using an improved version of the pole-face-windings and figure-of-eight loop powering

The working point of the CERN Proton Synchrotron, which is equipped with combined function magnets, is controlled using pole-face-windings. Each main magnet consists of one focusing and one de-focusing half-unit on which four pole-face-winding plates are mounted containing two separate coils each, called narrow and wide. At present they are connected in series, but can be powered independently. In addition, a winding called the figure-of-eight loop, contours the pole faces and crosses between the two half units, generating opposite fields in each half-unit. The four optical parameters, horizontal and vertical tune and chromaticity, are adjusted by acting on the pole-face-winding currents in both half units and in the figure-of-eight loop, leaving one physical quantity free. The power supply consolidation project opened the opportunity to use five independent power supplies, to adjust the four parameters plus an additional degree of freedom. This paper presents the results of the measurements that have been made in the five-current mode together with the influence of the magnetic nonlinearities, due to the unbalance in the narrow and wide winding currents, on the beam dynamics

High-Current Low-Voltage Power Supplies for Superconducting Magnets

In a synchrotron accelerator, the beam trajectory is controlled thanks to magnets, where superconducting technology allows to generate very strong magnetic fields. This was a key element in the construction of the Large Hadron Collider (LHC), the world largest accelerator. Such magnets need special power supplies providing very high DC current under low voltage. In the frame of High Luminosity-LHC (HL-LHC), stronger superconducting magnets are developed and require enhanced supplies. This article reviews the present power supply topologies and introduces new concepts: HL-LHC project offers an opportunity for upgraded system, increased operational performances as well as integrated energy storage to recover energy from the superconducting magnets

Comparative Study of Two-Quadrant DC/DC Stage in Power Supply for Superconducting Magnets

To improve the performances of the present European Organization for Nuclear Research (CERN) Large Hadron Collider (LHC), a new family of power supplies for Superconducting Magnets (SCM) is being designed to enhance the operating cycle and recover magnetic-stored energy. Those specific magnets require low-voltage high-current high-precision isolated power supplies. This paper compares different modes of operation for 4-quadrant full-bridge DC/DC converter and its reduced 2-quadrant variant, with emphasis placed on semiconductor losses and overall electrical performances. From the presented comparative study, it can be seen that 2-quadrant topology combined with synchronous rectification offers the most interesting characteristics for considered application

Fifty years of the CERN Proton Synchrotron : Volume 2

This report sums up in two volumes the first 50 years of operation of the CERN Proton Synchrotron. After an introduction on the genesis of the machine, and a description of its magnet and powering systems, the first volume focuses on some of the many innovations in accelerator physics and instrumentation that it has pioneered, such as transition crossing, RF gymnastics, extractions, phase space tomography, or transverse emittance measurement by wire scanners. The second volume describes the other machines in the PS complex: the proton linear accelerators, the PS Booster, the LEP pre-injector, the heavy-ion linac and accumulator, and the antiproton rings.Comment: 58 pages, published as CERN Yellow Report https://cds.cern.ch/record/1597087?ln=e

The CERN PS multi-turn extraction based on beam splittting in stable islands of transverse phase space: Design Report

Since 2001 considerable effort has been devoted to the study of a possible replacement of the continuous-transfer extraction mode from the PS to the SPS. Such an approach, called Multi-Turn Extraction (MTE), is based on capture of the beam inside stable islands of transverse phase space, generated by sextupoles and octupoles, thanks to a properly chosen tune variation. Both numerical simulations and measurements with beam were performed to understand the properties of this new extraction mode. The experimental study was completed at the end of 2004 and by the end of 2005 a scheme to implement this novel approach in the PS machine was defined and its performance assessed. This design report presents the outcome of the studies undertaken both in terms of technical issues as well as of resources necessary to implement the proposed scheme

La nouvelle alimentation pulsée de 60MW à 0.5Hz pour le Synchrotron à protons du CERN: un système totalement statique avec stockage d’énergie par condensateurs

Le Synchrotron à proton (PS) du CERN est un accélérateur de particules mis en service en 1959. Aujourd’hui, il est plus que jamais un élément essentiel de la chaine des accélérateurs du CERN. Il reçoit les protons d’un pré-accélérateur à une énergie de 1.4GeV et il les accélère jusqu’à 25GeV. Les cycles d’accélération durent 1.2 ou 2.4 secondes et s’enchainent les uns à la suite des autres, 5000 heures par an. Cent un aimants sont répartis sur les six cents mètres de circonférence de la machine et créent un champ magnétique qui permet de conserver les protons sur la trajectoire circulaire de la machine. Ils sont tous connectés en série et alimentés par un seul convertisseur de puissance. En réalité, ce convertisseur est un système de puissance complexe comprenant un groupe tournant de 90MVA. Ce groupe est en service depuis 1968 et après plus de 200 millions de cycles, montre des signes de fatigue. Une nouvelle alimentation prendra bientôt la relève. La solution retenue est une solution innovante qui est basée sur des convertisseurs statiques associés à des bancs de condensateurs comme réservoir d’énergie locale. Cette nouvelle technologie a été développée par le CERN et réalisée par l’entreprise CONVERTEAM