Convertisseur DC-DC

Résumé

Un Convertisseur DC-DC est un circuit d'électronique de puissance ou un dispositif électromécanique qui convertit une source de courant continu (DC) d'un niveau de tension spécifié à un autre différent. C'est un type de convertisseur de puissance électrique. Les niveaux de puissance considérés par de tels circuits vont de très bas (petites batteries) à très haut (transmission de puissance à haute tension voire très haute tension). Histoire Avant le développement des semi-conducteurs de puissance, une façon de convertir la tension d'une alimentation en courant continu en une tension plus élevée, pour des applications de faible puissance, était de la convertir en courant alternatif en utilisant un vibrateur, puis un transformateur élévateur et enfin un redresseur. Lorsqu'une puissance plus élevée était nécessaire, on utilisait souvent un groupe moteur-générateur, dans lequel un moteur électrique entraînait un générateur qui produisait la tension souhaitée. (Le moteur et le gé

Source officielle

https://fr.wikipedia.org/wiki/Convertisseur_DC-DC

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In view of the Large Hadrons Collider experiments upgrade, where the inner front-end electronics will require higher supply power, a new power distribution scheme has to be designed. This thesis presents a new and more efficient scheme based on step-down DC-DC converters, which will be placed close to front-end electronics where it will be exposed to intense radiation (250 Mrad) and magnetic field (4Tesla). Other than tolerance to these fields, additional constrains are small volume and mass and low noise emission not to affect the sensitive front-end electronics. Since no commercial component can meet these requirements, an Application Specific Integrated Circuit (ASIC) DC/DC converter has been developed and is presented in this work. The chosen converter topology is the buck because it presents the best compromise in terms of efficiency and low mass among the different compared topologies. Radiation hardness can be achieved with appropriate choice of the semiconductor technology combined with layout modifications. Magnetic field tolerance is attained with the use of an air core inductor whose shape can be toroidal for limiting the magnetic field emissions. All the ASIC building blocks are presented in this thesis likewise their design methodology: their schemes and the transistors sizing are discussed as well as the AC analysis to grant the stability of the output voltage over the selected range of frequencies. Three different prototypes had been integrated in the two chosen semiconductor technologies (mainstream and backup). Tests showing high efficiency (up to 85%) and the required level of radiation hardness are presented and discussed.

EPFL2012

Chargement

Low noise DC to DC converters for the sLHC experiments

Stefano Michelis

The development of front-end systems for the ATLAS tracker at the sLHC is now in progress and the availability of radiation tolerant buck converter ASICs enables the implementation of DC to DC converter based powering schemes. The front-end systems powered in this manner will be exposed to the radiated and conducted noise emitted by the converters. The electromagnetic compatibility between DC to DC converters and ATLAS short strip tracker hybrid prototypes has been studied with specific susceptibility tests. Different DC to DC converter prototypes have been designed following a noise optimization methodology to match the noise requirements of these front-end systems. The DC to DC converter developed in this manner presents a negligible emission of noise that was confirmed by system tests on an ATLAS tracker front-end module prototype. As a result of this, power converters can now be integrated in close vicinity of front-end chips without compromising their overall noise performance.

2010

Chargement

Enhanced-performance integrated Resonant Switched-Capacitor and Buck DC-DC converters for application in extreme radiation and magnetic field environments

Giacomo Ripamonti

DC-DC converters based on Application Specific Integrated Circuits (ASICs) have been developed in this doctoral work for the High-Luminosity Large Hadron Collider (HL-LHC) experiments at CERN. They step down the voltage from a 2.5 V line and supply a load current up to 3 A. The main focus has been the miniaturization of the converters while maintaining high efficiency, together with the improvement of the dynamic performance and the minimization of the impact of substrate parasitic devices. These are challenges that industry and research are facing to power modern microprocessors, with the aim of minimizing the system volume, cost and power consumption, while guaranteeing good regulation performance. Miniaturization is a key requirement for application in the HL-LHC experiments, since any added material is detrimental for the physics performance. In addition, the converters must be tolerant to a high magnetic field (up to 4 T) and to ultra-high levels of radiation. Tolerance to the magnetic field is achieved by employing air-core inductors (which are the bulkiest components on the board), while radiation-hard ASICs have been designed in this work in a commercial 130 nm CMOS technology by extensively applying hardening by design techniques. Converters using two different architectures have been designed: a buck converter, which had been identified in a previous work as a good option to achieve high efficiency and low mass, and a Resonant Switched-Capacitor (ReSC) converter, which can further increase the power density while keeping high efficiency. A novel dual-edge pulse width modulator for the buck converter that has improved dynamic performance compared to conventional solutions has been designed and implemented. Its small-signal response has been modeled, and the model has been validated by measurements. In addition, this thesis proposes an integrated system that monitors in real-time the voltage stress experienced by the devices of the buck converter and adjusts its operation accordingly, in order to guarantee the required reliability, while maximizing the efficiency. The main building block of this system has been designed and has proved to be fully functional. A substrate-currents-aware characterization method that allows the evaluation of the impact of substrate parasitic devices on the circuit performance and reliability has been also devised, and it has been applied to select the best floor-plan for the buck converter. A novel control scheme that optimizes the efficiency of the ReSC converter for the whole load current range by adopting different operation modes has been proposed and implemented. This thesis reports the steady-state analysis of each mode and a small-signal model for one of them. The buck converter uses a 100 nH inductor, and the last prototype shows a peak efficiency of 88.4% for the 2.5 V-to-1.2 V conversion. It complies with the radiation specifications, and mass production will soon start. The designed prototype ReSC converter employs a 12 nH inductor, and its area occupancy and thickness are respectively 20% and 55% lower than the buck. Its efficiency is larger than that of the buck converter in a range of conversion ratios and load currents, reaching a peak efficiency of 91.4% for the 2.5 V-to-1.2 V conversion. Radiation tests have highlighted that the converter complies with Total Ionizing Dose specifications. By introducing a few improvements, a future prototype could be close to production readiness.

EPFL2020

Chargement

Enhanced-performance integrated Resonant Switched-Capacitor and Buck DC-DC converters for application in extreme radiation and magnetic field environments

Giacomo Ripamonti

EPFL2020