Jean-Paul Ferrieux

Novel Half-Bridge Inductive DC–DC Isolated Converters for Fuel Cell Applications

This paper proposes a new class of converters based on the inductive input converters for the design of a power electronic interface for fuel cell (FC) applications. After studying the half-bridge structure, two soft-switching dc-dc converters are analyzed: one operating in zero-voltage-switching (ZVS) mode and the other in zero-current-switching (ZCS) mode. The ZVS converter can overcome the drawbacks of the original structure but is more complicated. The ZCS converter cannot operate at duty cycles below 0.5, but is simpler and more suitable for FC applications. Flexible choice of components, low losses, high efficiency, and modular converter possibility are all interesting characteristics of these converters. Their operation principle and characteristics are presented in this paper. Experimental results on 2 kW converters of each structure validate the theoretical analysis.

Current-source resonant converter in power factor correction

A 3 kW AC/DC converter is studied to comply the following conditions: power factor correction, output voltage regulation, electrical insulation, high efficiency. In this study we are interested in current-source resonant converter topologies with two energy storage elements and electrical insulation which allow the leakage inductance of a transformer to be included in order to achieve smaller size and lighter weight.

Boost-chopper-derived PFC rectifiers: interest and reality

This work presents an overview of single-phase boost-chopper-derived power-factor-correction rectifiers. Converters are presented for several control strategies in continuous and discontinuous current mode operations. The presentation highlights the main characteristics of the converters and underlines harmonic content over a wide frequency range. A methodology is derived to compute these harmonics in order to facilitate the analysis and performance evaluation of the converters. Based on this methodology, a comparison is conducted in order to highlight advantages and drawbacks of the most popular converters and control strategies. A table is given where main converter critical parameters are summarized in order to help the designer, in converter and operating mode selections. Practical results are provided to validate the modeling technique.

PFC full bridge rectifiers EMI modeling and analysis-common mode disturbance reduction

Switched mode power supplies must comply with electro-magnetic interference (EMI) regulations. Due to technological improvements, switching frequencies have been increased leading to reduced passive component values but also greater EMI levels, especially conducted common mode disturbances. This paper presents a simple and effective EMI forecast method to study and to analyze the conducted EMI effects before prototype testing. The methodology is validated and applied to the single phase full bridge power factor correction (PFC) rectifier. Several techniques to reduce common mode current (CMC) levels created by the converter are presented. The study is based on high frequency models and understanding of phenomenon. Looking at the control strategies and/or the propagation paths, it is demonstrated that EMI levels may be reduced. It is shown that with symmetrical EMI propagation paths, synchronized control strategies such as bipolar pulse width modulation (PWM) are preferred and lead to reduced CMC levels. On the other hand, with asymmetrical propagation paths, unipolar and half bridge control strategies may be preferred to reduce both differential mode current (DMC) and CMC levels. Results are validated using practical experiments performed under EMI regulation testing conditions.

A Global Study of a Contactless Energy Transfer System: Analytical Design, Virtual Prototyping, and Experimental Validation

This paper presents a design methodology dedicated to a two-winding transformer with large air gap and magnetic cores. To design this kind of components, it is necessary to consider the influence of inductive parameters on electrical magnitudes and the converter, which supplies this magnetic device. Indeed, this kind of a magnetic device has a large leakage inductance and a small magnetizing inductance. Therefore, to transfer the desired power, the transformer needs important reactive energy to magnetize magnetic core and to provide leakage flux. Like inductive parameters can be determined only when geometry is known, sizing has to be iterative. Moreover, resonant converters can be used to compensate inductive behavior, but modify electrical constraints of the transformer. A robust algorithm of design and all necessary tools are presented in order to make it easier to size such components. After the analytical design, 3-D FEM simulations and experimental measurements have been carried out in order to validate the theoretical study. Moreover, the power electronics converter has been optimized in order to improve the efficiency of power transfer. A prototype of 1.6 kW 100 kHz with an air gap of 6 mm has been realized with its converter. The global efficiency is 93.3%.

Optimized linearization via feedback control law for a STATCOM

Much attention has been paid to FACTS devices. The STATCOM (static compensator) is a FACTS device used to maintain voltage stability and is usually represented as a time-invariant model. This model can then be used to design an efficient nonlinear control law, based on exact linearization via feedback. In this paper, the control law is optimized in order to stabilize the internal dynamics of the STATCOM. Furthermore, the model is implemented in the EUROSTAG software in order to analyse the influence of the control law on the transient response of the power system.

Modeling and Computation of Losses in Conductors and Magnetic Cores of a Large Air Gap Transformer Dedicated to Contactless Energy Transfer

This paper focuses on the study of the losses in conductors and magnetic cores of a large air gap transformer dedicated to contactless energy transfer. It is composed of two E -shaped cores and two windings. In order to estimate the losses, homogenization method and three-dimensional finite-element method (3D-FEM) have been used. Indeed, the equivalent complex properties of the windings composed of Litz wire, and magnetic core in ferrite have been calculated from homogenization method. Then, they have been implemented in 3D-FEM simulations to compute copper and iron losses with accuracy and by considering working condition of the magnetic component. Theoretical approach is validated by experimental results for a prototype of 1.6 kW-100 kHz.

A Simplified Resonant Pole for Three-Level Soft-Switching PFC Rectifier Used in UPS

Efficiency of high-power uninterruptible power supplies (UPSs) is a fundamental criterion regarding the permanent use of such a device. A state of the art on soft switching over constraint of UPS application has been made. The principle of auxiliary resonant commutated pole using autotransformer has been identified as the most interesting way to increase efficiency or switching frequency. Its application for multilevel converters has been studied. A simplified resonant pole has been proposed for a three-level rectifier used as power factor corrector. The design criteria have been discussed. A single phase of a 200-kVA three-level rectifier has been realized and qualified in switching mode. To assess the gain of this principle, the switching losses have been measured on the prototype in both hard and soft switching. The switching losses have been divided by two.

Copper losses of flyback transformer: search for analytical expressions

Because analytical expressions are required to run optimization software, this subject is very topical. This work uses equivalent permeability to homogenize the winding structure and approximations for the window field. A progressive approach leads to the needed expressions for a transformer built around a gapped ferrite core. At every step, analytical expressions are compared to Flux3D simulation.

Volume optimization of a PFC flyback structure under electromagnetic compatibility, loss and temperature constraints

The aim of this paper is to present an analytical optimization approach of a flyback structure in PFC mode. Indeed, softwares like Saber, Pspice or Simplorer are effective means for the power electronics structure time-domain studies. However, if these structures have an AC input and a high switching frequency (various time scales), time-domain simulation becomes painful and expensive in memory and computing time. The study of EMC performances is also difficult because of the line impedance stabilizer network (LISN) time-constants which comes to penalize the time-domain simulation. In addition, in sizing and optimization process, results in short computing times are needed, so the time-domain simulation may be too time consuming. In this way, the paper proposes to carry out a compromise between the model accuracy and the tool rapidness and recommends the use of analytical models to optimize the passive element volume of a flyback structure by respecting EMC standards, by minimizing the whole losses dissipated in the structure (conduction and switching semiconductor losses, core and copper losses in the transformer) and by constraining the semiconductor junction, the winding and the magnetic circuit temperatures. Firstly, analytical models of the flyback structure for these various optimization aspects are developed, validated by numerical simulation or measures and integrated in an optimization process. Then, the optimization results are presented and validated thanks to a measurement workbench of the flyback structure.