EPE Journal Volume 17-1 
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EPE Journal Volume 17-1 - Editorial
EPE Journal Volume 17-1 - In Memoriam
EPE Journal Volume 17-1 - Papers



 EPE Journal Volume 17-1 - Editorial 

Welcome to EPE 2007 in Denmark - Aalborg  [Details]
By Frede Blaabjerg, Aalborg University
EPE Journal 17-1, Editorial -"Welcome to EPE 2007 in Denmark - Aalborg", written by Prof. Frede Blaabjerg, Aalborg University, EPE 2007 Conference Chairman


 EPE Journal Volume 17-1 - In Memoriam 

In Memoriam - Prof. Dr. Ir. Em. Gaston Maggetto  [Details]
By B. Sneyers
In Memoriam of Prof. Dr. Ir. Em. Gaston Maggetto, who passed away on the 9th of February 2007.


 EPE Journal Volume 17-1 - Papers 

Modelling of the supercapacitors during self-discharge  [Details]
By P. Venet, Z. Ding, G. Rojat, H. Gualous

The self-discharge behaviour of supercapacitors is an important factor because it determines the duration time of stored energy on open circuit. For the supercapacitor technology with activated carbon and organic electrolyte, the self-discharge is based on two mechanisms [1]. The first is due to the diffusion of ions from regions of excess ionic concentration. The second is due to the leakage of charge across the double-layer at the electrolyte-carbon interfaces. This paper treats the modelling of the supercapacitors, which takes into account the self-discharge phenomenon. Supercapacitor characterization is presented and analyzed, particularly the behaviour of self-discharge. To establish the supercapacitor model parameters, it's proposed to supplement an existing equivalent circuit model [2] by adding some new elements, which can be, describe the supercapacitor self-discharge behaviour. Simulation and experimental results are presented and compared.

Five-Level Inverter Topology for Induction Motor Drives With Common-Mode Voltage Elimination in Complete Modulation Range  [Details]
By P. N. Tekwani, R. S. Kanchan, K. Gopakumar, A. Vezzini

Common-mode voltage (CMV) generated by different topologies of the pulse width modulated (PWM) inverters causes shaft voltage, bearing current and ground leakage current in the induction motor (IM) drive system. Consequently the premature mechanical failure (fluting) of machine bearings and conducted electromagnetic interference (EMI) are observed in the multilevel PWM inverter fed IM drive systems. A five-level inverter topology with switching state combination selection strategy for PWM control is proposed for an IM drive for complete elimination of CMV in the entire operating range of the drive, including over-modulation. The proposed scheme is based on a dual five-level inverter fed open-end winding IM drive structure. Each individual five-level inverter of the proposed drive is formed by cascading a three-level neutral point clamped (NPC) inverter with two conventional two-level inverters. Hence, the proposed individual five-level inverter offers simple power-bus structure with less number of power diodes as compared to the conventional NPC five-level inverter. The proposed open-end winding IM drive structure requires nearly half the dc-link voltage and provides increased number of redundant switching state combinations as compared to a single five-level NPC inverter fed conventional IM drive. The proposed CMV elimination scheme is experimentally verified on a 1.5 kW openend winding IM drive.

A Space Vector PWM Technique for Symmetrical Six-Phase Voltage Source Inverters  [Details]
By D. Dujic; A. Iqbal; E. Levi

Six-phase a.c. motor drives are usually supplied from two-level six-phase voltage source inverters (VSIs), which are controlled using appropriate PWM techniques. Most of the existing work applies to the asymmetrical six-phase VSI, supplying an asymmetrical a.c. machine (two three-phase windings shifted in space by 30° degrees) with two isolated neutral points. However, it has been shown recently that a symmetrical six-phase induction machine (equidistant spacing of all six-phases, with 60° spatial displacement between any two consecutive phases) offers the same quality of performance as the asymmetrical machine, provided that good quality current control and an adequate PWM technique are utilised for the symmetrical six-phase VSI (Fig. 1) control. Since this requires sinusoidal VSI output voltages (neglecting the PWM ripple), a space vector PWM technique (SVPWM) is described in this paper, such that sinusoidal or at least nearsinusoidal output voltages are generated across the whole range of the available output voltage fundamental for the sixphase load with a single neutral point. Operation of the SVPWM scheme is investigated by extensive experimentation and time-domain waveforms and spectra are given for inverter leg, phase-to-neutral, line-to-line and common mode voltages, as well as for the load current, for a variety of operating conditions. Total voltage harmonic distortion (THD) is also calculated using experimental results and is used as a figure of merit in evaluation of the quality of performance of the SVPWM schemes.

Hybrid circuit breaker test bench  [Details]
By G. Bats; P. Ladoux; J.M. Blaquière; M. Francis

The target application of the Hybrid Circuit Breaker presented in this paper is a 6.6 kV/60 Hz network for an electric ship. This Hybrid Circuit Breaker is based on a series association of IGCTs (Integrated Gate Commutated Thyristors) and a fast mechanical switch. In this new topology, thanks to the IGCT turn off control, the fault current is strongly limited and the mechanical switch, turned off at zero current, provides the voltage sustaining. To validate the principle of this Hybrid Circuit Breaker, the authors propose a test bench that can provide a 50 Hz sinusoidal short circuit current with a 18 kA-peak value and a maximum di/dt of 20kA/ms. This test bench displays interesting results and validates many key points of the new topology.

Simple Control of Photovoltaic Generator Systems with High-Speed Maximum Power Point Tracking Operation  [Details]
By Y. Toshiya; O. Katsumi; M. Osamu

A simple control method for photovoltaic power generation systems is proposed. This achieves very-high-speed maximum- power-point tracking (MPPT): the controller finds out the optimal operating point within 2 milliseconds. Although this control method is based on the so-called “perturb-and-observe method”, the perturbing signal generator for MPPT operation is not necessary; switching ripples by the DC/DC converter are used as the perturbing signal. This controller measures the photovoltaic array power and tracks the optimal point with consideration of dynamic characteristics of the arrays. The proposed controller is cost effective because it can be implemented by a simple analog circuit; the controller is simplified in comparison with the conventional methods. The high performance of the proposed method is verified by experiment.

Comparison of the Induction Motors Stator Fault Monitoring Methods Based on Current Negative Symmetrical Component  [Details]
By A. Lebaroud; A. Khezzar; A. Bentounsi; G. Clerc

This paper presents a survey of the diagnosis methods detecting the stator faults of the induction machines without modeling. The fault signature is based on the analysis of the negative sequence symmetrical component of the current. Two approaches are described and compared: the spectral analysis of the signature using the Discrete Fourier Transforms (DFT), the Short-time Discrete Fourier Transform (SDFT), the Gortzel algorithm and the synchronous demodulation of the current space vector. The theoretical principles of these methods are presented and their performances compared. The main purpose of this study lies in the investigation of the computational tools dedicated to the diagnosis and minimization of computing time. These methods are applied to an induction machine of 1.1 kW.