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Alfred Rufer

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Related publications (215)

Page 2 of 11

Proposal and Validation of Medium-Frequency Power Transformer Design Methodology

Alfred Rufer

Power electronics is continuously evolving toward higher power densities. Consequently, volume, weight, and material reduction are becoming major design issues, which lead the research focus toward high/medium-frequency power conversion systems. This paper ...

2011

Analysis of Empirical Core Loss Evaluation Methods For Non-Sinusoidally Fed Medium Frequency Power Transformers

Alfred Rufer

Nowadays medium voltage conversion systems, like traction and energy distribution systems, aim to increase power density. Volume, weight and material reduction are gaining the market today. Due to the development of new high power semiconductor devices a n ...

2008

Fuzzy Logic Control of the Cross Connected Intermediate Level (CCIL) Voltage Source Inverter

Alfred Rufer

The Cross Connected Intermediate Level (CCIL) Voltage Source Inverter Topology was first introduced in 2007 [1]. The idea behind this novel multilevel topology is to explore the area of reduced number of component topologies producing large number of volta ...

2009

Energetic Macroscopic Representation of A Linear Reciprocating Compressor Model

Alfred Rufer, François Gallaire, Philippe Barrade, Mahbod Heidari

This article introduces the energetic macroscopic representation (EMR) as approach for the dynamic nonlinear modeling of a reciprocating air compressor. EMR has been introduced recently for research development in complex electromechanical systems and is b ...

Elsevier2015

Sizing of a Supercapacitive Tank: Finite Elements Thermal Modelling

Alfred Rufer, Philippe Barrade

The sizing process of a supercapacitive tank is today a well-known procedure. It enables the identification of the number of cells needed to match energy requirements. In some cases, this number must be increased, in order to match the power needs of the a ...

2008

Efficiency Considerations for the Fast Charge of Supercapacitors in the Frame of Low Voltage Applications

Alfred Rufer, Philippe Barrade, Simon Delalay

Even if supercapacitors present a reduced energy density, they allow to store a significant amount of energy which leads to a significant autonomy for applications with reduced energy needs. The main advantage of supercapacitors is to compensate a limited ...

2010

A Multilevel Power Converter with Integrated Storage for Particle Accelerators

Alfred Rufer

The PS accelerator (Proton-Synchrotron) at CERN (European Organization for Nuclear Research) is composed of one hundred magnets connected in series. During a cycle of 2.4 seconds, the active power at the magnets terminals varies from plus to minus 40 MW. A ...

2007

A High Efficiency Pneumatic Drive System Using Vane-Type Semi-Rotary Actuators

Alfred Rufer

A compressed air driven generator is proposed, where the pneumatic energy is converted into mechanical energy using two vane-type rotational actuators. The use of a second actuator with a higher displacement in order to produce a thermodynamic expansion al ...

UNIV NIS2021

Design Considerations for the Fast Charge of Supercapacitors in the Frame of Low Voltage Applications

Alfred Rufer, Philippe Barrade, Simon Delalay

Even if supercapacitors present a reduced energy density, they enable to store a significant amount of energy, which leads to a significant autonomy for applications with reduced energy needs. The main advantage of supercapacitors is there to compensate a ...

2011

Principle of a hybrid Compressed Air and Supercapacitors Energy Storage system with Maximum Efficiency Point Tracking

Alfred Rufer, Philippe Barrade, Sylvain Lemofouet-Gatsi, Félix Grasser

This paper presents a hybrid energy storage system based on Compressed Air Energy Storage (CAES), where the extraction of energy is done within maximum efficiency conditions. As the maximum efficiency conditions impose the level of converted power, an inte ...

2003

A Fully Analytical PEM Fuel Cell System Model for Control Applications

Alfred Rufer, Félix Grasser

Maintaining a fuel cell (FC) system in correct operating conditions when subjected to fast load changes requires good system control. The best results are typically achieved using model-based control strategies. This paper elaborates a control-oriented pro ...

2007

Optimization-Based Voltage Support in Traction Networks Using Active Line-Side Converters

Alfred Rufer, Behrooz Bahrani

Low system voltage in traction networks, mainly caused by active power absorption of locomotives, adversely affects the performance of the locomotives and also the power transmission capability of the catenary line. This paper introduces a voltage support ...

2013

Today’s and Tomorrow’s Meaning of Power Electronics within the Grid Interconnection

Alfred Rufer

Power Electronics is expected to become a major component in the field of the global electric power management, as it is already today within most of electric power applications like variable speed drives or other conventional user applications. From the e ...

2007

The Dream of Efficient Energy Storage - From Bess, Kers & Co to the Hybrid Power Plant

Alfred Rufer

Storage is an important domain of the energy sector, with its traditional, classical solutions for smaller and larger amounts of energy. Energy storage has become of higher importance in relation with the development of alternative energy sources, called a ...

IEEE2017

Analysis and Development of a New Compressor Device Based on The New Finned Piston

Alfred Rufer, Mahbod Heidari

In the general frame of Compressed Air Energy Storage system (CAES), the LEI Laboratory of EPFL has introduced the concept of dry finned piston. The main goal is to achieve energy storage by means of compressed air thanks to high isothermal efficiency comp ...

2013

Global Loss Evaluation Methods for Nonsinusoidally Fed Medium-Frequency Power Transformers

Alfred Rufer

Medium-voltage conversion systems, such as traction and grid-connected converters, are continuously evolving toward higher power densities. Consequently, volume, weight, and material reductions are becoming major design issues, which lead the research focu ...

2009

Modular Converter Architecture for Medium Voltage Ultra Fast EV Charging Stations: Dual Half-Bridge-based Isolation Stage

Alfred Rufer, Michail Vasiladiotis, Behrooz Bahrani

The concept of ultra fast charging of Electric Vehicles (EVs) is expected to contribute significantly to their widespread utilization in long-distance travels. Towards this direction, emerging power electronic topologies will be the key components of the d ...

2014

Towards the Isothermal Gas Compression—A Novel Finned Piston-Cylinder with Increased Efficiency

Alfred Rufer

In this paper, a novel concept of a finned piston system is presented and analyzed in which the compression heat is continuously extracted from the compression chamber. The resulting compression characteristic moves in the direction of an isothermal proces ...

2024

The Equivalent Electron Density Concept for Static and Dynamic Modeling of the IGBT Base in Soft- and Hard-Switching Applications

Alfred Rufer, Serge Pittet

The transient and static behavior of an insulated gate bipolar transistor (IGBT) are analyzed through finite elements simulations and physically based equations. The standard model using a bipolar transistor driven by a MOSFET is abandoned for three partia ...

2007

Impact of Grid Asymmetries on the Operation and Capacitive Energy Storage Design of Modular Multilevel Converters

Alfred Rufer, Michail Vasiladiotis, Nicolas Cherix

The grid-connected modular multilevel converter (MMC) is very likely to operate under asymmetric grid conditions. Such a converter features several unique characteristics, whichmake its analysis different from other types of power converters in similar cas ...

Institute of Electrical and Electronics Engineers2015