Publications by Alfred Rufer | EPFL Graph Search

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A new converter topology for drives is presented in this paper: a three-phase multilevel converter with separately regulated dc power supplies. The dc voltages are provided by medium-frequency dc–dc converters. The applications for the converter are especially high-power traction systems, where the voltage applied to the induction motor is bigger than 1 kV. The motor current is of a very high quality, compared to a classical three-phase converter. This allows keeping the switching frequency low by using pha

Similar to the classical solution of hydraulic pump-turbine plant, new means for accumulation of eletrical energy are given for lower but respectable quantities by the so called BESS (Battery Energy Storage System) and SMES (Super conducting Magnet Energy Storage). Another energy accumulator is given by using mecanichal kinetic energy of fly-wheel. Each system has advantages and disadvantage from the point of wiew of the quantity of stored energy and magnitude of the instantaneous usable power. A realistic

This paper compares different cascaded and multilevel topologies to interface supercapacitors to a dc bus in regenerative braking applications. It is shown that the modular multilevel dc/dc converter (MMC) can benefit from both reduced voltage and increase ...

A new isolated DC-DC converter is presented suited for high voltage applications. It is based on the series connection of NPC inverter cells, using semiconductor devices with lower voltage blocking capability than the total input voltage. The galvanic isol ...

This paper presents a vector current control method tailored for single-phase voltage source converters. In order to imitate the behavior of a three-phase system, the Fictive Axis Emulation (FAE) concept is employed. The latter is able to synthesize the ro ...

Maintaining a fuel cell system in correct operating conditions when subjected to fast load changes requires good system control. Best results are typically achieved using model based control strategies. This paper elaborates a control oriented PEM fuel cel ...

A topology based on the Modular Multilevel Converter (MMC) is presented, using two MMC linked by a medium frequency transformer. The back to back structure proves to have effective circuit breaker properties and reduced passive components. Due to the adopt ...

Cross regulation is the main technical challenge 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 ...

Supercapacitors are new components ale to store a high energy density aven if this energy is still lower than the energy batteries can store. This paper shows how supercapacitors can be used to supply electric vehicle such as busses and tramways. The "on-board" supercapaitors need a fast loading at some stations. This needs a high power, not always suitable when a distribution network is too weak, or when the power supplied by a network must be limited. Such type of limitations will hav o be more considered

This paper presents a bidirectional modular DC/DC converter. It consists of two Modular Multilevel Converters (MMC) linked by a transformer to achieve galvanic isolation. This topology serves as “DC transformer” interfacing low and medium voltage DC grids. ...

The cascaded H-Bridge multilevel active rectifier is an emerging converter topology, which offers significant advantages, such as modularity and high flexibility for a wide range of applications, including traction systems, industrial automation plants, un ...

PFC rectifiers are more and more used as front end circuits for low and mid sized apparatus. Especially for the eigh current applications, the size and weight of passive components are an imprtant factor, also for the economic aspect. The number and size of the active switches of classical PFC scheme, together with the design of heatsinks must be carefully investigated. A new possibility has been investigated using the current sharing on a higher amount of silicon devices, together with the effect of cancel

Multilevel Converters and battery energy storage systems (BESS) are key components in present and future medium voltage networks, where an important integration of renewable energy sources takes place. The Modular Multilevel Converter (MMC) offers the capa ...

This paper presents a Discrete-time Model Predictive-based Control strategy for the voltage regulation of an islanded distributed generation (DG) unit. The DG unit includes a voltage source converter (VSC) interfaced to the grid through a switch and a coup ...

Large physics experimentation as in particle accelerators or in nuclear fusion is often characterised by a strong and modulated power demand, incompatible with the power availability of the grid. Therefore, large facilities for short-term energy storage ha ...

In the transportation field, the empty weight of the vehicle has to be as light as possible in order to have the highest energetic efficiency. For onboard storage electrical systems, dc/dc converters are usually used to control the power flows in the vehic ...

Recently, multilevel applications have know n many improvements. Initially introduced to answer the problem of the series-connection of components in medium voltage applications, multilevel topologies have now to serve new purposes. Recent multilevel techn ...

This paper proposes a cascade or multiloop digital control strategy for the voltage regulation of a three-phase islanded single distributed generation (DG) unit microgrid and its dedicated load. The cascade control strategy consists of an inner dq-currents ...

In the framework of the diversification of the electric vehicle charging standards, the configurable modular multilevel converters (CMMC) have been found as one of the best concepts for a universal and flexible charging system. It is foreseen that they inc ...

A bidirectional buffered charging unit for EV's is presented, allowing the charge with high power even if the line current capability is limited. The bidirectional buffer is connected to the AC line and is mainly dedicated to vehicles with on-board AC-DC c ...

Alfred Rufer

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A Three-Phased Multilevel Converter for High-Power Induction Motors

Modern power conversion for complementary energy storage

Design and Control of a Modular Multilevel DC/DC Converter for Regenerative Applications

High-Power High-Voltage Isolated DC-DC Converters using an NPC Balanced Capacitive Divider

Fictive Axis Emulator-based State Feedback Vector Current Control for Single-Phase Voltage Source Converters

A fully analytical PEM fuel cell system model for control applications

A versatile DC/DC converter based on Modular Multilevel Converter for energy collection and distribution

Multivariable Control of Single-Inductor Dual-Output Buck Converters

Power smoothing and high power fast energy exchange between storage systems

Modular DC/DC Converter: Comparison of Modulation Methods

Model Predictive-based Control Method for Cascaded H-Bridge Multilevel Active Rectifiers

A High Current, Low Ripple, Low Weight PFC Rectifier Using a Standard Power Module

Analysis and Control of Modular Multilevel Converters with Integrated Battery Energy Storage

Model Predictive-based Voltage Regulation of an Islanded Distributed Generation Unit

A novel 60 MW Pulsed Power System based on Capacitive Energy Storage for Particle Accelerators

High Efficient Interleaved Multi-channel dc/dc Converter Dedicated to Mobile Applications

Cross-Connected Intermediate Level (CCIL) Voltage Source Inverter

A Cascade Voltage Controller for Three-phase Islanded Microgrids

Influence of High Frequency Charge-Discharge Cycling Induced by a Configurable Modular Multilevel Converter

A Bidirectional Buffered Charging Unit for EV's (BBCU)