Numerical simulation of electromagnetic and mechanical phenomena in the end-winding region of three-phase induction machines*

Abstract

The 3-D geometry of the motor end-region consisting of the end-winding together with the motor cross-section, housing and complementary construction parts is very complex, which makes the analytical computations of the electromagnetic phenomena related to the end-region very cumbersome and non accurate. Furthermore, owing to the complicated geometry, also the preparation of the numerical model is extremely time consuming and numerical simulation very computationally pretentious. The aim of this paper is to present the numerical approaches, which overcome these problems by introducing methods to simplify the modeling procedure of the machine end-winding and the consideration of the rotor current excitation. In this paper the use of the proposed methods is demonstrated by computing the induction motor end-winding leakage inductance, the computation of the eddy-current losses in the machine clamping-plates and by the calculation of the mechanical deformations of the synchronous generator end-winding under operating load conditions. Analysis of the time-variant magnetic field has been performed using T, F À F formulation for a 3-D timeharmonic finite element method (FEM). Numerische Simulation von elektromagnetischen und mechanischen Vorgä ngen im Stirnbereich von dreiphasigen Asynchronmaschinen.Die dreidimensionale Geometrie des Motor-Stirnbereichs, bestehend aus dem Wickelkopf, dem Gehä use und ergä nzenden Konstruktionsteilen, ist ä ußerst komplex und deshalb fü r analytische Berechnungen sehr schwer zugä nglich. Die Komplexitä t der Geometrie erfordert darü ber hinaus zeitaufwä ndige Modellierungen und rechentechnisch anspruchsvolle Simulationen. In dieser Publikation werden numerische Ansä tze vorgestellt, die es erlauben, die Wickelkopf-Geometrie und die Rotorstrom-Erregung vereinfacht zu erfassen. Die Anwendung der gezeigten Methoden wird zunä chst anhand der Berechnung der WickelkopfStreuinduktivitä ten und der Wirbelstromverluste in den Pressplatten gezeigt. Zudem werden die mechanischen Verformungen des Wickelkopfes eines Synchrongenerators im Nennbetrieb untersucht. Fü r die Analyse des zeitvariablen Magnetfeldes wurde die T, F À F-Formulierung in Verbindung mit einer 3-D zeitharmonischen Finite-Elemente-Methode (FEM) angewandt.Schlü sselwö rter: elektrische Maschine; Finite-Elemente-Methode; numerische Analyse IntroductionThe simulation of phenomena associated with machine end-regions are very challenging owing to the complex geometry of the endwinding together with the motor cross-section and supporting construction parts. In the design process, often diverse semi-empirical formulas are employed in order to compute the end-region effects. Regretfully, such analytical approaches are rather inaccurate due to the complicated geometry. Moreover, the employment of numerical procedures is also very demanding, owing to a laborious modeling procedure and high computational costs. These parasitic effects are not to be disregarded in the design process, since they are in close correlation to the machine performanc...

Numerical simulation of the end-winding deformations in the synchronous machine under symmetrical short-circuit conditions using FEM*

“…1) have been calculated using a network simulation model based on the Park transformation. In contrast to (Stermecki et al, 2011), in this research the rotor current excitation has been neglected. The assumption has been made that the field components provoked by the short-circuit stator currents dominate over the rotor fields.…”

“…As pointed out in the introduction, a transient time-stepping numerical simulation has been carried out. Similarly to the method presented in (Stermecki et al, 2011) where the magnetic field and forces have been evaluated for the synchronous generator nominal operation conditions, the non-conforming FE mesh approach has been employed in this research, too. Since the magnetic problem has been described using the T, F -F formulation, the stator current excitation (J) has been represented by a current vector potential T 0 satisfying the following condition:…”

OVE Nachrichten

“…Whereas the previous two problems required two-dimensional models, the simulation of the end-windings of electrical machines and computing the corresponding inductances as well as losses in the structural parts has made the development of three-dimensional models necessary [6][7][8]. In Fig.…”

Analysis on Electromagnetic Force Properties of End Windings in Turbo-Generators

“…Under the action of the electromagnetic forces, mechanical responses such as deformation, stress, elastic strain, etc., will be caused. The deformation (displacement) and stress distribution of the stator end winding in single-phase short circuit, double-phase short circuit, and three-phase short-circuited case are studied [8,11,12]. Yang Zhao employed the finite element software ABAQUS/CAE to obtain the transient magnetic force and it is found that the vibration mode of the end windings is ellipse [12].…”