engleski

3D finite element analysis of magnetic stress in the end region of a turbogenerator

This study involves 3D finite element (FE) modelling of a loaded turbogenerator for the purpose of analyzing flux density in the stator core end and force density acting on the stator teeth of the first packet of a laminated stator core. The principal tasks of the study are: developing 3D finite element model to make it suitable for simulation of on-load condition of the turbogenerator with rotation of the rotor, calculation of the axial flux density in the stator core end in general, and more locally in front of the tooth and inside the tooth of the first packet at the moment when the axial flux is maximal and display of the force density distribution on the stator tooth surfaces of all modelled lamination layers of the first packet at the moment when the force is maximal. All 3D finite element simulations have been performed using commercially available software Infolytica MagNet. In order to obtain the most realistic model and to provide maximum feasible accuracy of the obtained results, all significant geometric features of the studied generator and the properties of materials have been taken into account within the limits of the available software and PC hardware. Those include: detailed representation of all parts of the generator geometry in 3D space that have significant influence on magnetic field solution inside the generator and in the surrounding space in its end region, modelling of rotor rotation, modelling of laminated core using nonlinear materials with anisotropic permeability and anisotropic conductivity, inclusion of eddy current effects in the laminations of the first packet and tuning of the finite element mesh density in the critical regions considering the presence of induced eddy currents and skin depth of the magnetic material. In the process of modelling certain simplifications described later in more detail had to be introduced, but always with an attempt to minimize their negative effect on accuracy of the final results.

Turbogenerator ; 3D finite element ; Magnetic stress ; End region

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