Abstract-A general approach for the frequency-domain homogenization of multi-turn windings in 2D FE calculations is presented. First a skin and proximity effect characterization of the individual conductors, of arbitrary crosssection and packing, is obtained using a representative 2D FE model. Herein three excitation modes are considered, viz current and flux density in two perpendicular directions. In practical cases, the three modes are independent and the obtained frequency-dependent impedance and complex reluctivity tensor can be readily used in a FE model of the complete device. By way of example and validation, the method is applied to an inductor having an airgap and one of three different windings. The homogenized model produces global results (impedance versus frequency) that agree well with those obtained with a more precise FE model. In the latter each turn of the winding is explicitly modelled and finely discretized.

The authors present a novel time-domain homogenization technique for laminated iron cores in three-dimensional (3-D) FE models of electromagnetic devices when using the magnetic vector potential formulation. The method is based on a polynomial orthogonal decomposition of the variation of the induction throughout the thickness of the laminations. The nonconstant components, due to skin effect, produce additional degrees of freedom and equations for the homogenized core. Insulating layers of finite width between the laminations (fill factor 1) are taken into account as well. A linear 3-D axisymmetric test case is considered. The results agree well with those obtained with the reference model, in which all laminations are finely discretized and the eddy currents are directly modeled.

No abstract

The authors present a novel nonlinear homogenization technique for laminated iron cores in 3D FE models of electromagnetic devices. It takes into account the eddy current effects in the stacked core without the need of modelling all laminations separately. A nonlinear constitutive magnetic law is considered. The system of nonlinear algebraic equations obtained after time discretisation is solved by means of the Newton-Raphson scheme. By way of validation the method is applied to a 3D FE model of a laminated ring core with toroidal coil.

No abstract

No abstract

No abstract

This paper deals with the incorporation of a vector hysteresis model in 2D finite-element (FE) magnetic field calculations. A previously proposed vector extension of the well-known scalar Jiles-Atherton model is considered. The vectorised hysteresis model is shown to have the same advantages as the scalar one: a limited number of parameters (which have the same value in both models) and ease of implementation. The classical magnetic vector potential FE formulation is adopted. Particular attention is paid to the resolution of the nonlinear equations by means of the Newton-Raphson method. It is shown that the application of the latter method naturally leads to the use of the differential reluctivity tensor, i.e. the derivative of the magnetic field vector with respect to the magnetic induction vector. This second rank tensor can be straightforwardly calculated for the considered hysteresis model. By way of example, the vector Jiles-Atherton is applied to two simple 2D FE models exhibiting rotational flux. The excellent convergence of the Newton-Raphson method is demonstrated.