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8. Influence of the rotor eccentricity on the torque of a cage induction machine

Author

Silwal Bishal, Rasilo Paavo, Belahcen Anouar, and Arkkio Antero

Subjects
cage induction machine, dynamic eccentricity, electromagnetic torque, energy balance, finite element method, harmonics, Electrical engineering. Electronics. Nuclear engineering, TK1-9971
Abstract

The non-uniform air gap in an electrical machine caused by rotor eccentricity creates an asymmetrical flux-density distribution in the air gap. This can affect the nominal torque produced by the machine. Eccentricity also produces forces that act on the rotor which may also have an effect on the torque. Thus, it is important to know how the torque of the machine behaves. In this paper, the torque of a cage induction machine is studied when the machine has dynamic eccentricity. The study is performed using the finite element method and a magnetic vector potential formulation. The torque is calculated by the method of energy balance. The harmonic components of the torque are also analyzed. The results show that the machine under eccentricity does not exhibit the same torque as a normal healthy machine. The harmonic components around the first principal slot harmonic is most affected.

Published
2017
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13. Wire-Arc Additive Manufacturing of Reduced Activation Ferritic Martensitic (RAFM) Steel

Author

Reichenbach, Alexandar and Silwal, Bishal

Subjects
RAFM steel, Additive manufacturing, wire-fed AM
Abstract

RAFM steel has been considered as the candidate material for an in-vessel component of the fusion wall reactor. Known as F82H in Japan and Eurofer-97 in Europe, RAFM steel is not commercially available. The goal of this research project is to fabricate and study the technical feasibility of producing RAFM steel welding wire with wire arc AM. Metal-cored wire is a tubular electrode comprised of an outer metal sheath with alloying powdered materials inside the core. Applications of such wire include but not limited to welding, thermal spray, cladding and additive manufacturing (AM). The advantage of using the metal-cored wire is that a higher deposition rate, higher side-wall fusion, can be achieved, and more important, special alloys for special applications can be manufactured at relatively lower cost. A preliminary investigation of wire arc AM of RAFM steel was carried out using Ar-CO2 (c-25) gas. A design of experiments with GMAW based power source waveform using the metal cored wire was conducted to study the printability. The microstructure and mechanical properties (hardness and toughness) was tested, and the data were analyzed and compared with the literature.

Published
2022
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29. Computation of eddy currents in a solid rotor induction machine with 2-D and 3-D FEM

Author

Belahcen, Anouar, Elektroniikan laitos, Arkkio, Antero, Silwal, Bishal, Belahcen, Anouar, Elektroniikan laitos, Arkkio, Antero, and Silwal, Bishal

Abstract

Although a two-dimensional numerical analysis of an electrical machine provides an approximately accurate solution of the electromagnetic field in the machine, a three-dimensional study is needed to understand the actual phenomena. But due to the large problem size and the complex geometries, the three dimensional model requires a huge amount of degrees of freedoms (DoFs) to be solved, which is not possible with a limited computing resources. Therefore, a coupled 2D-3D model can be the best alternative to solve such type of problems. In this thesis, a 2-D finite element analysis is performed on a solid rotor induction motor by an in-house software FCSMEK. The eddy current in the solid steel rotor was computed. A 3-D model for the same machine was built and solved in COMSOL MultiphysicsTM. To reduce the computation time of the 3-D model, the solution of the 2-D model was used as the source to the 3-D model where the stator current density is used as a transferred variable. The eddy currents are computed and the results from both 2-D and 3-D simulations are compared. Other quantities of interest such as the torque of the machine computed with the 2-D and 3-D models are also computed and compared.

Published
2012

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