High Current, Low Voltage Power Converters for LHC Present Development Directions

The superconducting LHC accelerator requires high currents (12.5 kA) and relatively low voltage (~10 V) for its magnets. The need to install the power converters underground is the driving force for reduced volume and high efficiency of the power converters. Moreover, the machine will require a very high level of performance from the power converters, particularly in terms of DC stability and dynamic response. To meet these requirements switch-mode techniques will be used. This paper gives a survey of current switch-mode converter topologies for high DC current output. The presentation is primarily focused on the various methods for low-loss switching in DC power converters operating with high switching frequency (20 - 50 kHz). A modular concept is being studied, using several current sources in parallel, to adapt to the various circuits and also provide redundancy

Full Range ZVS Phase Shifted Power Converter with "Poles"

The study and development of a quasi-resonant power converter, with Full Bridge - PhaseShifted - Pulse Width Modulation (FB-PS-PWM) topology is presented. The originality of thepaper is the adding of resonant networks (poles) on each leg to get soft commutation (ZeroVoltage Switching ZVS) over the full range of the output current. The design of the polestructure and the component ratings are described. Simulations and a [1000A-15V] converterprototype, using dual-thyristor, validate the theoretical studies

High Precision and High Frequency Four-Quadrant Power Converter [+-600A,+-12V]

The LHC (Large Hadron Collider) particle accelerator makes extensive use of true bipolar power converters. All these converters will be installed in excavated caverns underground; hence the necessity for minimum volume and high efficiency for the power converters. This paper presents the design and the realisation of a compact (19", 6U) and high frequency (50 kHz) four-quadrant power converter [±600 A, ±12 V]. The obtained performance (DC stability, efficiency EMC,...) is presented and discussed

Four Quadrant Convertor [600A, 12V] Prototype for LHC

The CERN Large Hadron Collider (LHC) project will make extensive use of true bipolar power converters [±600 A, ±12 V]. The need to install the power converters in excavated caverns underground requires considerably reduced dimensions and high efficiency. Moreover, the LHC machine demands a very high level of performance from the power converters, particularly in terms of DC stability, dynamic response and also with regard to ElectroMagnetic Compatibility (EMC). To meet these requirements, soft-switching techniques are used. The design and the performance (DC stability, bandwidth, efficiency, EMC of a compact (6U) and high frequency (30 kHz) four-quadrant power converters are presented

High Current, Low Voltage Power Converter [20kA, 6V]: LHC Converter Prototype

The superconducting LHC accelerator requires high currents (~12.5kA) and relatively low voltages (~10 V) for its magnets. The need to install the power converters underground is the driving force for reduced volume and high efficiency. Moreover, the LHC machine will require a very high level of performance from the power converters, particularly in terms of DC stability, dynamic response and also in matters of EMC. To meet these requirements soft-switching techniques will be used. This paper describes the development of a [20kA,6V] power converter intended as a stable high-current source for D CCT calibration and an evaluation prototype for the future LHC converters. The converter is made with a modular concept with five current sources [4kA,6V] in parallel. The 4kA sources are built as plu g-in modules: a diode rectifier on the AC mains with a damped L-C passive filter, a Zero Voltage Switching inverter working at 20 kHz and an output stage (high frequency transformers, Schottky rectifi ers and output filters). The obtained performance (DC stability, bandwidth, efficiency, EMC,...) is presented and discussed

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

The State Socialist Mortality Syndrome

Death rates for working-age men in European state socialist countries deviated from general improvements in survival observed in the rest of Europe during the 20th century. The magnitude of structural labor force changes across countries correlates with lagged increases in death rates for men in the working ages. This pattern is consistent with a hypothesis that hyper-development of heavy industry and stagnation (even contraction) of the service sector created anomic conditions leading to unhealthy lifestyles and self-destructive behavior among men moving from primary-sector to secondary-sector occupations. Occupational contrasts within countries similarly show concentration of rising male death rates among blue collar workers. Collapse of state socialist systems produced rapid corrections in labor force structure after 1990, again correlated with a fading of the state socialist mortality syndrome in following decades