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Alfred Rufer

Cette personne a quitté l’EPFL

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Publications associées (215)

Page 3 sur 11

Analytical analysis of Quasi-Saturation Effect in PT and NPT IGBTs

Alfred Rufer, Serge Pittet

During the turn-on process insulated gate bipolar transistors (IGBTs) traverse a quasi-saturation region from the off.state to the on-state (saturation). The additional voltage drop due to the quasi.saturation of the junction hardly depends on the DC-link ...

2002

Hybrid Energy Storage System based on Compressed Air and Super Capacitors with MEPT (Maximum Efficiency Point Tracking)

Alfred Rufer, Sylvain Lemofouet-Gatsi

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

2005

A new solution for increasing the efficiency of an electric scooter with supercapacitors through a novel, interleaved multi-channel DC/DC converter

Alfred Rufer, Philippe Barrade

Scooters are a well-established transport system for short distances – particularly within cities. Currently, the majority of scooters are petrol powered. Their engines typically exhibit bad efficiencies and thus contribute to global warming by CO2 product ...

2005

Reversible DC/DC Converter as interface between Low and Medium Voltage DC Networks

Alfred Rufer, Stephan Kenzelmann, Carlo Arrioja

This paper introduces an isolated reversible DC/DC converter with a particular topology, which benefits from both the Neutral Point Clamped (NPC) structure and the series-parallel connection of converters. The key property of the proposed topology is the o ...

2011

New Optimized PWM VSC Control Structures and Strategies Under Unbalanced Voltage Transients

Alfred Rufer

Control structures and strategies have a critical influence on a power electronic converter’s behavior during disturbances. Most of the previous works in the field of pulsewidth modulation voltage-source converter (VSC) operation under unbalanced condition ...

2007

On The Strategies Towards Isothermal Gas Compression And Expansion

Alfred Rufer, Sylvain Lemofouet-Gatsi, Mahbod Heidari

Isothermal compression/expansion is regarded as the most promising process in many applications and many researchers and inventors have tried different methods to achieve this goal. The current article first studies the gradual roadmap from adiabatic towar ...

2014

Catenary Voltage Support: Adopting Modern Locomotives With Active Line-Side Converters

Alfred Rufer, Behrooz Bahrani

This paper proposes a voltage support scheme for traction networks, which compensates for the voltage drop along the catenary line to which locomotives are connected. The proposed method is based on the injection of capacitive reactive power through the cu ...

2013

Comparison of Control Strategies for Maximizing Energy in a Supercapacitor Storage Subsystem

Alfred Rufer, Philippe Barrade

A storage supercapacitor subsystem is studied for insertion in a series hybrid electric vehicle (Fig. 1). This subsystem is composed of a supercapacitor bank and a braking resistor used when the supercapacitor voltage is at its maximum value. Generally, wh ...

2009

Decoupled dq-Current Control of Grid-Tied Voltage Source Converters Using Nonparametric Models

Alfred Rufer, Alireza Karimi, Behrooz Bahrani

This paper presents a vector control strategy for regulating the current of grid-tied voltage source converters (VSCs) in a rotating reference frame. The proposed approach is based on shaping the open-loop and closed-loop transfer matrices of the system. S ...

Institute of Electrical and Electronics Engineers2013

Power Compensation Approach and Double Frame Control for Grid Connected Converters

Alfred Rufer, Daniel Siemaszko

The handling of weak networks with asymmetric disturbances implies the accurate handling of the second harmonic component appearing under unbalanced networks. This paper proposes a two-step approach using classic vector control for operating the current co ...

Ieee2013

A Flexible, High Efficiency, VSI-based HVDC Transmission System with Reduced Harmonics

Alfred Rufer, Aziza Benaboud

In this paper a High Voltage Direct Current (HVDC) transmission system is proposed, based on using three level three phase (3L3P) converters, coupled through a specific transformer connection in order to benefit from natural and selective harmonic cancella ...

2008

Expansion Work Recovery of Hydrogen for a FC-Truck-Tentative Design of an Expansion Machine

Alfred Rufer

Hydrogen powered vehicles use high-pressure reservoirs from which the gas is transferred to the low-pressure fuel-cell via a classical pressure reduction valve. In these systems no expansion work is recovered and the question is addressed of the potential ...

MDPI2023

Optimal Energy Management of an Improved Elevator with Energy Storage Capacity based on Dynamic Programming

Alfred Rufer, Philippe Barrade

Efficiency and energy consumption reduction are becoming a key issue in elevation applications. Energy Storage Systems (ESS) can play a significant role on this field, together with their associated Energy Management System (EMS) in order to optimize the o ...

Ieee2012

Multivariable Control of Single-Inductor Dual-Output Buck Converters

Alfred Rufer, Alireza Karimi, Behrooz Bahrani

Cross regulation is the main technical drawback of a Single-Inductor Multiple-Output (SIMO) dc-dc converter. This paper proposes a multivariable digital controller to suppress the cross regulation of a Single-Inductor Dual-Output (SIDO) buck converter in C ...

Ieee2013

A Five-Level NPC Photovoltaic Inverter with an Actively Balanced Capacitive Voltage Divider

Alfred Rufer

A new five-level photovoltaic Inverter is presented, implemented by associating a Multistage Stacked Boost Architecture (MSBA) with a 5-level NPC inverter. Ahead of the MSBA conversion stage, a conventional boost converter allows the operation of the PV ce ...

2015

Non-Isolated DC-DC Converters for High Power Appli-cations - Control of the Capacitive Voltage Divider

Alfred Rufer, Philippe Barrade

A non-isolated DC-DC converter is presented, based on the current diverter principle. The converter is foreseen for large power electronic applications where normally the converters are fed from DC supplies at a typical voltage level of around one or two k ...

2014

Modeling of a Vanadium Redox Flow Battery

Alfred Rufer

New concepts of power generation, the emergence of renewable energies as well as the liberalization of the electrical market have recently raised strong intereset in electricity storage technologies. The vanadium redox flow battery (VRB) is among the new s ...

2007

DC-DC Converter based on the Asymmetric Multistage Stacked Boost Architecture with Feed-Forward Control for Photovoltaic Plants

Alfred Rufer, Gina Kristin Steinke

A new feed-forward control technique for a DC-DC step-up converter based on the asymmet-ric Multistage Stacked Boost Architecture (MSBA) is presented in this paper. The proposed closed loop control scheme can provide improved accuracy in the steady-state o ...

2016

Bond Graph Model Representation of a New Reciprocating Finned Air Compressor

Alfred Rufer, Mahbod Heidari

A new finned reciprocating air compressor model is developed recently for compressed air energy storage. First the mechanism of operation of the new compressor is described. The complexity of the design encouraged us to develop the model based on the bond ...

2014

A Closed Loop Control Strategy for a Frequency-Only Converter with High Efficiency

Alfred Rufer, Aziza Benaboud

Many electric power generators use gas turbines as power sources, coupled through a mechanical gearbox in order to adapt their synchronous speed to the optimal rotation speed of the turbine. This paper proposes to replace the mechanical gearbox with a flex ...

2007