Journal Volume 12 Issue 2

Electromagnetically Excited Audible Noise - Evaluation and Optimisation of Electrical Machines by Numerical Simulation

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Christoph Schlensok, Benedikt Schmülling, Michael van der Giet, Kay Hameyer

Disturbing vibrations and noise of electrical machines are gaining impact. Therefore, it is necessary to estimate the electromagnetic, structure-dynamical, and acoustic behaviour of the machine during designing and before prototyping. An adequate tool is numerical simulation applying the Finite-Element Method (FEM) and Boundary-Element Method (BEM) allowing for the structured analysis and evaluation of audible noise also caused by manufacturing tolerances. The methods developed and proved at the Institute of Electrical Machines (IEM) at RWTH Aachen University can be applied to any electromagnetic device in general.

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Additional losses by magnetic field harmonics in the rotor bars of asynchronous machines and their influence

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Uwe Schuffenhauer, Hans Kuß

Optimizing the efficiency of modern asynchronous machines requires the knowledge of the particular loss components. In this contribution a method shall be presented, where by the transient FEM-calculation the copper losses in the rotor bars by harmonic field effects and the consequential originating harmonic currents can be estimated. By this way the determination of the current density of the rotor current harmonics is carried out along the height of the rotor bar.

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Rotor power loss in a PM SM by calculation, simulation and measurements, mutual verification of methods

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Jean Claude Vannier, Robert Kaczmarek, Zhu-Yun Wang, Andry Randria

The subject of the paper is the comparison of four complementary methods of the rotor loss estimation in a PM SM, supplied by a PWM voltage source. An ANSYS based finite element model produces values of W, the magnetic energy stored, and P, the rotor losses. On analytical level the machine is represented by a parallel two elements equivalent circuit for each voltage harmonic. Its parameters are estimated using P and W values. Finally, the eddy current losses representation in the ANSYS code is verified for magnets under study by direct losses measurements.

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Extreme possibilities of circuital models of electrical machines

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Tadeusz J. Sobczyk

The paper presents possibilities of so-called circuital mathematical models of electric machines, in which the machine is treated as a set of magnetically coupled coils. It is a very popular class of models used for analysis of operational conditions of electric machines. However, the progress in numerical solutions of electromagnetic filed causes the interest of researchers to shift into so-called field-models. This paper shows the author’s opinion on extreme possibilities of circuital models putting main attention to their creation, simplification and solving.

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Multiresonant ZVS CUK Convertor

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Elżbieta Szychta

The article presents properties of multiresonant ZVS Cuk converter. The control system of the converter is based on PWM technique. The operating range of the converter is defined where ZVS operation is assured. Control characteristics are given and the converter’s efficiency is defined. The converter’s operation is analysed on the basis of simulation testing.

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Modelling and analysis of the Quadrature-booster phase shifter with PWM AC bipolar matrix-reactance chopper and passive load

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Zbigniew Fedyczak, Maciej Jankowski, Paweł Szcześniak

This paper deals with a quadrature-booster phase shifter for power flow control and for transient stability improvement in AC transmission systems. The PWM AC bipolar matrix chopper (MC) is proposed for the control of the qudrature voltage component of the original voltage. There are presented in this paper both steady and transient state analyses of a transmission system with passive load based on averaged circuit models. Furthermore, simulation and experimental test results obtained in a three-phase 3 kVA laboratory model are also presented.

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Mitigation of the wind generation integration related power quality issues by energy storage

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Kyung Soo Kook, Yilu Liu, Stan Atcitty

The wind power which has been expected to be a promising alternative energy source can bring new challenges when it is connected to the power grid due to the fluctuation nature of the wind and the comparatively new types of its generators. This paper illustrates a possible solution to mitigate these integration issues of the wind power by application of the energy storage to the wind farm in power systems focusing on its short-duration perspective.

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Methods of voltage unbalance estimation in electric power networks

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Zbigniew Olczykowski, Andrzej Wąsowski

Methods of voltage unbalance estimation based on the theory of symmetrical components and the method of differential — angular coefficients of asymmetry have been discussed. It has been proposed the last one to estimate the asymmetry of square absolute voltage value, as useful for distorted processes.

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Unified power quality conditioner in a grid-connected photovoltaic system

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Marcelo C. Cavalcanti, Gustavo M.S. Azevedo, Bruno A. Amaral, Francisco A.S. Neves

This paper presents a system that provides photovoltaic generation as well as the functions of a unified power quality conditioner. The system can be controlled for current harmonics and reactive power compensation simultaneously by using a converter operating as active shunt filter. The other converter is used as active series filter and it compensates voltage harmonics or voltage sags and swells. Using only an inverter in photovoltaic energy conversion process, the system presents increased efficiency when compared to the conventional systems.

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Contactless multipolar double-fed asynchronous generator for windmills

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Nikolaj Levin, Vladislav Pugachov, Leonids Ribickis, Anastasia Zhiravetska

A multipolar contactless doubly-fed asynchronous generator is considered where the primary and secondary generation windings are arranged on the teeth of the stator, while the rotor is tooth-like and without windings. Analytical treatment of such a generator has been performed and the basic equations that allow the parameters and performance of the machine to be calculated in generation mode of operation have been obtained.

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