Accurate prediction of power loss distribution within an electrical device is highly desirable as it allows thermal behavior to be evaluated at the early design stage. Three-dimensional (3-D) and two-dimensional (2-D) finite element analysis (FEA) is applied to calculate dc and ac copper losses in the armature winding at high-frequency sinusoidal currents. The main goal of this paper is showing the end-winding effect on copper losses. Copper losses at high frequency are dominated by the skin and proximity effects. A time-varying current has a tendency to concentrate near the surfaces of conductors, and if the frequency is very high, the current is restricted to a very thin layer near the conductor surface. This phenomenon of nonuniform distribution of time-varying currents in conductors is known as the skin effect. The term proximity effect refers to the influence of alternating current in one conductor on the current distribution in another, nearby conductor. To evaluate the ac copper loss within the analyzed machine a simplified approach is adopted using one segment of stator core. To demonstrate an enhanced copper loss due to ac operation, the dc and ac resistances are calculated. The resistances ratio ac to dc is strongly dependent on frequency, temperature, shape of slot and size of slot opening.

This paper considers a Brushless Direct Current (BLDC) machine prototype with six poles and 36 stator slots including a three phase double-layered distributed winding. Presented modifications of rotor construction are identified in order to achieve the best possible compromise of eddy-current losses and cogging torque characteristics. The permanent magnet (PM) eddy-current loss is relatively low compared with the iron loss; it may cause significant heating of the PMs due to the relatively poor heat dissipation from the rotor and it results in partial irreversible demagnetization. A reduction in both losses is achieved by magnet segmentation mounted on the rotor. Various numbers of magnet segmentation is analysed. The presented work concerns the computation of the no-load iron loss in the stator, rotor yoke and eddy-current loss in the magnets. It is shown that the construction of the rotor with segmented magnets can significantly reduce the PM loss (eddy-current loss). The eddy-current loss in PMs is caused by several machine features; the winding structure and large stator slot openings cause flux den sity variations that induce eddy-currents in the PMs. The effect of these changes on the BLDC motor design is examined in order to improve the machine performance. 3-D finite-element analysis (FEA) is used to investigate the electromagnetic behaviour of the BLDC motor.

The purpose of this paper is to focus on the loss separation of non-grain-oriented electrical steels used for speed-variable rotating electrical machines. The impact of laser-cutting, used in prototype manufacturing and of flux density harmonics, occurring locally in the lamination, on the loss distribution is studied in detail. Iron losses occurring under operation can physically be separated in different loss components. In this paper, a frequency-based loss model with parameters identified for single-sheet tester specimens, cut in strips of different widths, is therefore used. Moreover, a time-domain approach considers loss distributions occurring from higher harmonics. Hysteresis losses having high sensitivity to cut edge effects are calculated by the well-known Jiles-Atherton model adapting the frequency-based loss parameters. The model is validated by free-curve measurements at a single-sheet tester. It has been shown that the studied elliptical hysteresis model becomes inaccurate particularly for specimens with small strip widths with similar dimensions as teeth of electrical machine laminations. The incorrect mapping of losses occurring from minor hysteresis loops due to higher harmonics is concluded. The results showconsequently that both, the impact of a cut edge effect and local distributions of flux density harmonics need to be considered in terms of accurate iron loss prediction of electrical machine design.

Switched reluctance motors (SRMs) are still under development to maximise their already proven usefulness.Amagnetic circuit of theSRMcan be made of soft magnetic composites (SMCs). The SMCs are composed of iron powder with dielectric and have a lot of advantages in comparison to commonly used electrical steel. The paper deals with the modelling and analysis of theSRMproduced by Emerson Electric Co. forwashing machines. Numerical calculations and modelling were done using the FEMM 4.2 program. Magnetic flux densities and magnetic flux lines were calculated, as well as electromagnetic torque and inductance for changing the position of a stator to a rotor. The obtained results were compared with other measurement results and are quite similar. The developed numerical model will be used for the project of a motor with an SMC magnetic circuit.