An iron-loss model for laminated ferromagnetic cores of electrical machines is presented and applied to estimate the core losses of an induction machine with finite element analysis. Skin effect in the cross section of the core lamination is modeled using a set of sinusoidal basis functions while locally considering both the hysteretic material properties and the excess field caused by domain wall motion. After spatial and time discretization, a single nonlinear equation system is obtained. An accurate vector Preisach model, the differential reluctivity tensor and the Newton-Raphson method guarantee excellent convergence of the iteration procedure. Results from the model correspond well to iron-loss data obtained by measurements.
This paper presents a simple and efficient magnetic equivalent circuit (MEC) model for surface axial flux permanent magnet synchronous machines. The MEC model is used to solve all the electromagnetic properties of the machine including the no load, full load voltages, cogging torque, torque ripple and stator iron core losses. Moreover, this approach can be extended for all surface permanent magnet synchronous machines. The main novelty of this approach is the development of a static system, which accounts for the rotation. The model takes into account the rotor rotation via time dependent permanent magnet magnetization sources. The static system matrix facilitates a very fast solving. In addition, to take into account the 3D effect, a multi-slicing of the machine in the radial direction is done. This boosts the simulation time to only 60 seconds for 6 slices and 50 time steps including the non-linear behaviour of the stator elements with a great accuracy. Additionally, the number of elements in the MEC can be adjusted to reduce the computational time. This model is verified by means of 3D and 2D multi slice finite element (FE) models. In addition, experimental validations are also provided at the end. Index Terms-Analytical modeling, Axial flux permanent magnet synchronous machines (AFPMSM), Cogging torque, Magnetic equivalent circuit (MEC), Surface permanent magnet synchronous machines (SPMSM), Torque ripple. Peter Sergeant received the M.Sc. degree in electromechanical engineering and the Ph.D. degree in engineering sciences from
Effect of mechanical stress on the magnetic loss of electrical steel sheets is analyzed utilizing the statistical loss theory. The focus of the study is on the variation of the excess loss component with the applied stress and its correlation with the hysteresis loss. The model and its correlation are validated by performing comprehensive measurements at various combination of induction levels, frequencies and stresses. It is found that the excess losses can be modeled with sufficient accuracy by their correlation with the hysteresis losses over a wide range of stresses, frequencies and flux densities.
A novel approach for predicting magnetic hysteresis loops and losses in ferromagnetic laminations under mechanical stress is presented. The model is based on combining a Helmholtz free energy -based anhysteretic magnetoelastic constitutive law to a vector Jiles-Atherton hysteresis model. This paper focuses only on unidirectional and parallel magnetic fields and stresses, albeit the model is developed in full 3-D configuration in order to account also for strains perpendicular to the loading direction. The model parameters are fitted to magnetization curve measurements under compressive and tensile stresses. Both the hysteresis loops and losses are modeled accurately for stresses ranging from -50 to 80 MPa.
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