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The high-frequency common-mode voltage introduced by power converters, using conventional modulation techniques, results in common-mode current that has the potential to cause physical damage to the shaft and bearings of electric drives as well as unwanted tripping of ground fault relays in motor drives and electrical networks. The paper aims to provide a complete elimination of common mode voltage using a matrix converter (MC) with a new modulation strategy that reduces the size of the power converter system considerably. Further, a new MC topology is proposed to eliminate the common mode voltage with improved voltage transfer ratio (VTR).

The direct MC topology is selected, as it is the only converter topology that has the potential to eliminate common mode voltage in direct AC to AC systems. Using the rotating space vector technique, common mode voltage is eliminated but this reduces the VTR of the converter. To improve the VTR, a modified MC topology with a modified rotating space vector strategy is proposed. In addition, for improving the power factor at the input, the input current control strategy is developed.

The use of rotating space vector technique eliminates the common mode voltage even under all input abnormalities like unbalance and harmonics. By applying positive and negative rotating space vectors, input power factor control can be achieved. However, the control range is limited from unity power factor to the output power factor. It is observed that in the current controlled technique the modulation index reduces further. It is also found that there is a reduction in switching stresses of individual switches in proposed topology compared to direct MC topology.

In this paper, a modified rotating space vector technique is applied to the proposed converter topology for elimination of common mode voltage with an increased VTR. The topology can be used for common mode voltage elimination in existing electric drives without the need for modifying the drive system.

A direct power control (DPC) of the doubly-fed induction generator (DFIG) is presented. A new method, which is based on the rotation of the space sector, clockwise or vice versa, is proposed to improve the performance of the switching table. Then, it is combined with a fuzzy system to have advantages of both rotation sector and fuzzy controller. The paper aims to discuss these issues.

In this paper, a new DPC of the DFIG is presented. To improve the performance of the switching table, a new method is proposed. The method is based on the rotation of the space sector, clockwise or vice versa. The excellence of the proposed method is proven. Then, it is shown that the performance of the system can be enhanced by using a fuzzy logic controller. The rotation method is combined with a fuzzy system.

Simulation shows that although sector rotation and fuzzy controller can improve the performance of the DFIG, a combination of both demonstrates a smoother response in order that reactive and active power ripples and THD of the injected current decrease in different speeds. Also, it is demonstrated that the proposed method is robust against parameters variations. However, a hardware experiment should be performed to be practically verified.

A sector rotation is proposed and its effect on the performance of the DFIG is considered. A simple method to write rules table is presented and the performance of sector rotation and fuzzy controller on the DFIG is analysed.

The paper suggests a fully digital technique, which may be successfully used for electric drives for road vehicles. The technique is based on the use of a feeding algorithm which allows the drive to electrically satisfy all traction requirements, i.e. forward and reverse speed or braking action. Theoretical considerations are supported by sample results of numerical simulations which confirm the practical suitability of the suggested technique.

In the dispersed generation system, power electronic converters allow for coupling between energy sources and the power grid. The requirements of Transmission System Operators are difficult to meet when the share of distributed energy sources of the total energy balance increases. These requirements allow to increase penetration of distributed generation sources without compromising power system stability and reliability. Therefore, in addition to control of active or reactive power, as well as voltage and frequency stabilization, the modern power electronic converters should support power grid in dynamic states or in the presence of nonlinear distortions. The paper aims to discuss these issues.

The research methodology used in this paper is based on three steps: Mathematical modelling and simulation studies, Experiments on laboratory test stand, Analyzing obtained results, evaluating them and formulating the conclusions.

The authors identified two algorithms, αβ-Filter and Voltage Controlled Oscillator, which are able to successfully cope with notch distortions. Other algorithms, used previously for voltage dips, operate improperly when the voltage grid has notching disturbances. This work evaluates six different synchronization algorithms with respect to the abilities to deal with notching.

The paper presents results of the synchronization algorithms in the presence of nonlinear notching interference. These studies were performed using the original hardware-software power grid emulator, real-time d’Space platform and power electronic converter. This methodology allowed us to exactly and accurately evaluate synchronization performance methods in the presence of complex nonlinear phenomena in power grid and power electronic converter. The results demonstrated that the best algorithms were αβ – Filtering and Voltage Controlled Oscilator.

In this paper, different synchronization algorithms have been tested. These included the classical Phase Locked Loop with Synchronous Reference Frame as well as modified algorithms developed by the authors, which displayed high robustness with respect to the notching interference. During the tests, the previously developed original test rig was used, allowing software-hardware emulation of grid phenomena.

This paper aims to suggest a parameter independent and simple speed estimator for primary field-oriented control of a promising electro-mechanical energy conversion device in the form of brushless doubly-fed reluctance machine (BDFRM) drive.

The speed estimation algorithm, in this context, is formulated using a modified secondary winding active power (mPs)-based model reference adaptive system (MRAS). The performance of the proposed estimator is verified through computer aided MATLAB simulation study, compared with conventional active power-based MRAS and further supported with experimental validation using a 1.6 kW BDFRM prototype run by a dSPACE-1103 controller.

The formulation of mPs-MRAS is insensitive to any machine parameters and does not involve any integration/differentiation terms. Thus, any deviation therein does not hinder the performance of the mPs-MRAS-based speed estimator. The proposed speed estimator shows stable behavior for variable speed-constant load torque operation in all the four quadrants.

The formulation of mPs-MRAS is insensitive to any machine parameter and does not involve any integration/differentiation terms.

The purpose of this paper is to develop a system for estimating the position of the active magnetic bearing (AMB) shaft. A new approach using the static and dynamic inductances and complex analytic signal to simplify the estimation procedure. Finite element (FE) simulations are introduced as a part of the system synthesis.

The paper presents an AMB displacement estimation system. The system is created with three inductive sensors. The position is computed from refined static and dynamic inductance obtained from complex analytic signals of flux and current. FE simulation is used to relate refined inductances to the displacement and to verify the model.

This paper shows the applicability of complex analytic signal transformation on estimation systems. The use of new refined inductance is presented in contrast to the classical approach of static and dynamic inductances. The paper shows that classical approach of static and dynamic inductance is not usable for the presented estimation system.

For the practical implementation of the presented system, it is necessary to know the exact dimensions of the AMB stator and the voltage and frequency used to supply the inductance estimation system.

The paper presents a system for estimating the displacement of AMB. The paper introduces the application of complex analytic signal to the estimation of AMB displacement. The mentioned signal is used to compute the new refined inductances. The comparison to the classical approach of static and dynamic inductances is given in this paper. The paper introduces FE simulations to the estimation system synthesis.

Gives introductory remarks about chapter 1 of this group of 31 papers, from ISEF 1999 Proceedings, in the methodologies for field analysis, in the electromagnetic community. Observes that computer package implementation theory contributes to clarification. Discusses the areas covered by some of the papers ‐ such as artificial intelligence using fuzzy logic. Includes applications such as permanent magnets and looks at eddy current problems. States the finite element method is currently the most popular method used for field computation. Closes by pointing out the amalgam of topics.

Discusses the 27 papers in ISEF 1999 Proceedings on the subject of electromagnetisms. States the groups of papers cover such subjects within the discipline as: induction machines; reluctance motors; PM motors; transformers and reactors; and special problems and applications. Debates all of these in great detail and itemizes each with greater in‐depth discussion of the various technical applications and areas. Concludes that the recommendations made should be adhered to.

Differential relaying is one of the most widely used techniques for protecting power transformers. The purpose of this paper is to discuss and cover a developed methodology for analyzing the signals obtained from the differential protection of power transformers.

The differential signal obtained from the protective relays of power transformers is analyzed in this paper, in order to establish a relation between time‐dependent symmetrical components and space vectors. As a result of the formulation of such a relation, specific patterns are obtained and classified for the plot of the space vector during fault and inrush conditions.

What was found in the course of the work? This will refer to analysis, discussion, or results. It has been found that the discrimination between inrush and fault conditions is possible by observing a characteristic asymmetry in the plots of the space vector. A method for dealing with the said asymmetries based on the absolute value of the space vector as obtained from the differential signal is proposed and discussed. The theoretical approaches given in the paper are further validated through finite element simulations and laboratory tests, which include linear and non‐linear loads, in order to account for more severe exploitation conditions.

A complete protective algorithm can be developed from the analysis of the methodology proposed, which avoids the spectral analysis, since the methodology is based in pattern analysis rather that in the latter technique.

The methodology provides faster identification of the fault during inrush condition, since the spectral analysis is prevented.

It may be stated that the major contribution of the paper is the methodology proposed for identifying internal faults in power transformers using pattern characterization of the plot of the space vector.

A tentative idea of introducing rotating electromagnetic force for dynamic balancing is presented in the paper. A method of generating the force is put forward, the force generated has adjustable magnitude, speed and phase angle. Working characteristics of the force are analyzed. Phase windings fed with half sine currents are designed to restrain pulsation of the force vector in space. Simulation results of a model indicate that a rotating force vector can be obtained by selecting a proper number of phases simultaneously fed with currents, which is able to meet the needs of ordinary engineering problems.