Article
A Boundary Integral Formulation on Unstructured Dual Grids for EddyCurrent Analysis in Thin Shields
Dipt. di Ingegneria Elettrica, Padova Univ.
IEEE Transactions on Magnetics (Impact Factor: 1.39). 05/2007; 43(4):1173  1176. DOI: 10.1109/TMAG.2006.890948 Source: IEEE Xplore
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 "where R and M are the classical resistance mass matrix and the magnetic matrix [2], respectively. This solution is more convenient than the one proposed in [5] since the system is symmetric. "
Article: A Boundary Integral Method for Computing Eddy Currents in Thin Conductors of Arbitrary Topology
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ABSTRACT: We present an effective technique to solve eddy current problems in thin conductors of arbitrary topology by a boundary element method based on a stream function. By considering a mesh of the thin conductor, which we assume to be a surface (i.e., an orientable combinatorial twomanifold embedded in R 3), the aim of this paper is to introduce a novel technique to render the stream function single valued when the thin conductor is not topologically trivial. In particular, a novel combinatorial algorithm to compute the appropriate cohomology generators in linear time worst case complexity is introduced, providing an effective and rigorous solution for the required topological preprocessing. Index Terms— Boundary element method (BEM), cohomology, eddy currents, stream function, thin shields with holes. 
Conference Paper: Mitigation of residential magnetic fields generated by MV/LV substations
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ABSTRACT: The design of a magnetic shielding arrangement for an indoor substation is considered. The aim of the intervention is to reduce the magnetic field intensity inside a room above the substation. Stray fields are mitigated by using metallic screens and by rearranging LV cables in order to limit intervention costs. A threedimensional electromagnetic analysis of stray fields is performed by means of an original integral code, whereas a twodimensional FEM software is used for assessing the shielding performance locally, in proximity of LV cables. Simulations show that the highest field attenuation levels are attained when phases of conductors and transformers are arranged in optimised configurations. The developed procedure is then applied to design a magnetic shield for a MV/LV substation. It is shown that measured and computed field r.m.s. values of the magnetic flux density are in good agreement.  [Show abstract] [Hide abstract]
ABSTRACT: We propose a novel 3D hybrid approach, based on a discrete formulation of Maxwell equations (the cell method CM), suitable for solving eddy current problems in unbounded domains. Field equations for magnetodynamics are expressed directly in algebraic form thanks to the CM. The eddy current problem inside bulk conductors is formulated in terms of discrete modified vector potential, whereas magnetic scalar potential is used in order to model the free space. The CM is coupled to the boundary element method by using a surface boundary operator, which maps the surface magnetic fluxes to the surface magnetic scalar potentials. This leads to a unique set of linear equations to be solved in terms of discrete potentials. The eddy currents in bulk conductors are then obtained from discrete potentials. It is shown that formulation of hybrid approaches can be simplified by expressing field equations directly in algebraic form without need of weighted residual techniques. An original strategy, based on Green’s formula for the magnetic scalar potential, is proposed in order to couple conducting parts to the exterior domain. Conducting bodies with multiply connected parts cannot be modelled by the proposed approach, since it is based on the magnetic scalar potential. The resulting global matrix is partially dense and nonsymmetric; therefore, standard iterative solvers such as GMRES have to be used. The proposed approach can be suitably used for analyzing eddy current problems involving models with high degree of complexity, large air domains and moving parts. These are typical of induction heating processes. This paper proposes a new 3D hybrid approach, based on a discrete formulation of Maxwell equations. A novel coupling strategy relying on integral electromagnetic variables, i.e. magnetic fluxes and magnetic scalar potentials, is devised in order to solve uniquely for eddy currents inside conducting bodies.