2008 18th International Conference on Electrical Machines

The suitability of solid rotor technology in a high power output hermetic natural gas compression application was studied. Two new solid-rotor designs for an 8 MW, 6.6 kV, 12000 min-1 and a 10 MW machine were done and the motors successfully tested. The former carries a purely solid, slitted rotor and the latter has a copper cage manufactured of copper bars inserted in solid rotor core ... View full abstract»

The homo-polar DC flux, which is generated in the air gap of a magnetically levitated two-pole induction machine by the by-pass flux of a nearby axial magnetic bearing, modulates the two-pole fundamental field of the induction motor. The additional modulation field wave generates a radial force, which rotates with the fundamental electric stator frequency. This disturbing force is analyzed and cal... View full abstract»

This paper presents the modeling, simulation and analysis of the dynamic behavior of a fictitious 2times320 MW variable speed pump-turbine power plant including hydraulic system, electrical equipments, rotating inertias and control systems using the software SIMSEN. First, the modeling of hydraulic and electrical components of the power plant is presented. Then the pseudo continuous approximation ... View full abstract»

The paper presents a new calculation method for induction motors with an unsymmetrical stator winding. In these cases, the usual T-equivalent circuit for stationary operation is no longer valid, but one coil of the machine has to be used as the smallest symmetry unit. Unsymmetrical windings may cause additional asynchronous and synchronous harmonic torques that might e.g. prevent the start-up. The... View full abstract»

Partial discharge (PD) mechanisms are widely acknowledged damage threads to high voltage windings of electrical machines. The immense number of papers on this subject and the development of prosperous PD monitoring industries provide the impression that PD is the only electrical damage mechanism which threatens high voltage machine insulation [1]. However, this is wrong because another electrical ... View full abstract»

Over the last few years industry branches with a growing demand for high purity and contamination-free high-acceleration spin processes, such as biotechnology, chemical, pharmaceutical and semiconductor industry, have tightened their cleanness specifications for the process environments. A recent trend to meet these specifications is to use magnetically levitated slice motors with air gaps being l... View full abstract»

A buried magnet rotor structure, which is supported only by permanent magnets, is proposed for medium speed permanent magnet machines. Different solutions with pole numbers six to fourteen are studied with electromagnetic and structural finite element simulations. An optimal solution with optimal pole number is discussed. View full abstract»

Using the analysis method for resolving the starting torque of line-starting permanent magnet (PM) synchronous machines with starting cage, the electromagnetic torque can be separated into two components, the driving ldquocage torquerdquo and the braking ldquomagnet torquerdquo. The correct saturation of the iron must be considered, when calculating the separate torque components. The sum of the t... View full abstract»

This paper deals with the sensorless-oriented design of interior permanent magnet (IPM) motor for the general industrial application. The finite element analysis is used to examine the influence of the IPM rotor geometry on the feasibility region for the sensorless rotor position detection. Consequently, the design guideline is established to obtain a suitable rotor geometry which can maximize the... View full abstract»

This study aims to estimate equivalent circuit parameters for a synchronous machine. The need for equivalent circuits rises from practical applications. Accurate models are needed for control design and power system analysis. The research was conducted using the 2D finite element analysis and the differential evolution algorithm. As an input to the synchronous machine, a pulse is used within the F... View full abstract»

The cross-magnetizing phenomenon of saturated synchronous machines plays an important role in their analysis using the two-axis frame models. To determine the parameters representing this phenomenon by the finite element method (FEM), the analysis has to be performed for excitations in the direct, quadrature and intermediate axes of the synchronous machines. This paper presents some investigations... View full abstract»

The idea of designing and manufacturing intelligent clothes with magnetic fibres is discussed in the paper. This paper deals with the creating 3-D computer structural models of magnetic microfibres, which could be introduced as the textile magnetic sensors or actuators. View full abstract»

An error estimation technique based on the L2 error norm is implemented in this paper for magnetostatic finite-element analysis. Convergence of both the global and local errors are used as indicators. The air gap is refined based on the rate of change in the calculated force and consists of layers. Results that highlight the accuracy of the combined methods for cogging torque calculatio... View full abstract»

In the paper a non-linear mathematical model for the performance assessment and the design improvement of small single-phase PM synchronous motor is proposed. The calculation of the model parameters is carried out by 2D FEM analyses suitably corrected to take also into account of the 3D effects. The procedure implemented in a numerical code allows to investigate significant design aspects related ... View full abstract»

This paper investigates simulation models for salient pole solid rotor synchronous machines through experimental model identification. Two different methods are used, the classical stand-still frequency response test method and the more recent prediction error method. The results are compared and analyzed. It is shown that a third order model is required to describe the machine dynamics accurately... View full abstract»

In induction motors with closed rotor slots the enclosure upper part of the rotor slot saturates during the machine operations, involving an additional non-linearity in the machines behavior. A simple locked rotor test gives prominence to this phenomenon. In fact, in this test the supply voltage versus adsorbed current characteristics are not linear. In the paper a single-phase induction motor equ... View full abstract»

The concept of power transformer design with a symmetric core construction (the hexa-transformer) provides a more compact solution compared to traditional technology based on an E-type core. This paper evaluates parameters of two 100 kVA three-phase transformers built according to both concepts. The evaluation includes calculations of induced voltages, inductances, core losses and weight differenc... View full abstract»

Various performance aspects of multi-phase machines are investigated with the main focus on 6-phase (dual stator) synchronous machines. It is shown that 6-phase machines have benefits over their 3-phase counterparts regardless of machine topology i.e., PM, induction or synchronous. Differences between 6-phase and 3-phase machines are emphasized through detailed design parameter sensitivity. It is ... View full abstract»

This paper describes the self-excitation characteristics of a hybrid excitation single-phase synchronous generator with the features of both wound-rotor and PM synchronous machines. The wound field provides field regulation and allows the field-strengthening operation. The voltage compensation of the generator uses the negative-phase sequence field in the field winding. View full abstract»

The asynchronous machine is the most popular machine in industry. The paper is about how machine current signature analysis (MCSA) can reliably diagnose faults in squirrel cage motors or generators and determinate if there is any difference in the application of this method when the same machine is working as motor or as generator. This paper focuses on the experimental investigation for incipient... View full abstract»