Showing papers presented at "European Conference on Power Electronics and Applications in 2001"

A Generalized Design Principle of a Uniform Step Asymmetrical Multilevel Converter For High Power Conversion

Abstract: This paper is focused on a general design principle of a uniform step multilevel converter, with K series-connected full bridges inverters per phase. A new design terminology is proposed and analytical relationships are established. The DC-voltage sources supplying partial inverters are supposed to be rationally unbalanced. The corresponding “Asymmetrical” topology provides more flexibility to the designer, and can generate a large number of levels (any odd number from 2K+1 to 3K) without increasing the number of H-bridges. Simulation results and experimental tests shown the reliability of the design approach suggested.

Unified power quality conditioner based on current source converter topology

Abstract: Nonlinear devices, such as power electronics converters, inject harmonic currents in the AC system and increase overall reactive power demanded by the equivalent load. Also, the number of sensitive loads that require ideal sinusoidal supply voltages for their proper operation has increased. In order to keep power quality under limits proposed by standards, it is necessary to include some sort of compensation. Different types of power quality compensators of higher or lower complexity have been reported. The aim of this paper is to present a unified power quality conditioner (UPQC) that consists of two three-phase current-source converters connected on the same inductive DC link. Such system has faster phase voltage control loop than its voltage-source converter based counterpart, as well as the inherent short circuit protection capability. Also, in this case passive filter connection between UPQC and the load is not needed, which minimizes the cost of the system.

P.W.M Current converter for electric energy production systems from fuel-cells

Abstract: Fuel Cells are destined to supply electric energy beginning from primary resources. A static DC-AC converter is necessarily inserted between the fuel cells and the distribution network. This paper describes a new P.W.M. strategy for a current source inverter. This modulation strategy reduces the energy losses and harmonics in the P.W.M. current source inverter. This technique allows the P.W.M. current source inverter to become a new feasible solution to adapt a low continuous voltage into a three-phase voltage of higher amplitude.

Multilevel Converter with 2 Stage-Conversion

Abstract: The use of electrical equipment in rail and ship transportation is bound to consideration on mass and size, particularly because of conventional low frequency transformers. On this paper, an optimized multilevel converter with medium frequency transformer is presented. It allows to adapt voltage from primary generators (6.6kV) to service use (440V). From a pseudo continuous model of the converter, we present a method to improve its working and to define a corresponding operating domain.

Brushless-DC Motor using Soft Magnetic Composites as a Direct Drive in an Electric Bicycle

Abstract: Recent advances in materials research have produced soft magnetic composites that can be considered for use in electrical machines. New drive concepts are needed to fully take advantage of this new material. An electric bicycle with a new drive with very good performance and low cost is presented. A major part of this drive is a new brushless-dc motor using soft magnetic composites. The motor is also suitable for other drive applications.

On a Three-Phase Modular Double Salient Linear Motor’s Optimal Control

Abstract: The three-phase modular double salient permanent magnet linear motor (DSPMLM) has several advantages over the classical hybrid linear motor. In this paper an adjustable speed control system is proposed for this motor. The motor is energised simply from a low cost readily available standard three-phase compact converter, which is connected to a microcontroller-based intelligent speed control unit. A sensorless closed-loop control strategy based on the so-called back-EMF-voltage detection of the un-energized command coils is proposed. All the drive system's characteristics are analysed by means of simulation. The SIMULINK programs are based on a circuit-field mathematical model of the motor. The results obtained prove the ability of the motor and confirm the usefulness of the presented control strategy.

Visual Diagnostics Based on Image Wavelet Transform

Abstract: The image processing described in this paper is used for visual quality control in ceramic tile production. The tiles surface quality is described by the surface defects. The described image processing is based on the discrete wavelet transform method. The diagnostic algorithm is described. It is based on comparing of the wavelet coefficients of the original image without surface defects and the real images of ceramic tiles. The method is verified by using the artificial defects on the image and sensitivity testing on failure contrast and size is done. The algorithm is evaluated experimentaly using the real tile images. The analysis of the detection capabilities and sensitivity expressed in nondetected failures and false proclaimed defect is done also. Optimal connection between the segment size and DSL for each type of surface failure could be used to make efficient system for quality control and failure classification in automated production process.

BLDC motor position detection at standstill

Abstract: In some applications, it is interesting to know the position of a BLDC Motor at standstill. This paper propose one solution using the saturation property of the motor. Principle, simulation and measures are presented. The results of industrial applications are exposed and discussed. Several preview works has been done on this subject. The purpose of this paper is to present a new method allowing to enhance the precision up to 2°. Furthermore, the method can be applied to all type of brushless DC motors, even with airgap or toothless ones