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The calculation of the leakage quasi‐stationary magnetic field of a three‐phase transformer with disk‐windings is presented in the paper. A mathematical model of the transformer based on Maxwell's equations has been applied. Computational results of the short‐circuit reactance have been compared with analytical formulas according to Richter's formulas.

A three‐dimensional analysis of the quasistationary, magnetic leakage field of a one‐phase transformer with asymmetrical disk windings is presented. A simplified mathematical model of the transformer based on Maxwell’s equations is applied. Computational results of the leakage reactance for asymmetrical disk‐type windings are compared with the analytical ones according to Richter’s formulae.

Analysis of test data monitored for a number of electric machines from the low volume production line can lead to useful conclusions. The purpose of this paper is to trace the machine performance to find quality-related issues and/or identify assembly process ones. In this paper, the monitoring of experimental data is related to the axial flux motor (AFM) used in hybrid electric vehicle (HEV) and in electric vehicle (EV) traction motors in the global automobile market.

Extensive data analyses raised questions like what could be the causes of possible performance deterioration of the AFM and how many electric motors may not pass requirements during operation tests. In small and medium research units of AFM for HEV or EV, engineers came across a number of serious issues that must be resolved. A number of issues can be eliminated by implementing methods for reducing the number of failing AFMs. For example, improving the motor assembly precision leads to reduction of the machine parameters deterioration.

Assembly tolerances on electric motor characteristics should be investigated during motor design. The presented measurements can be usable and can point out the weakest parts of the motor that can be a reason for the reduced efficiency and/or lifetime of the AFM. Additionally, the paper is addressed to electric motor engineers designing and/or investigating electric AFMs.

Performance of AFM was monitored for a number of identical motors from low volume production line. All tested motors were operated continuously for a long period of time and the tests were repeated every few weeks for half a year to check the reliability of motor design and indicate how much the motor parameters may change. The final results point how many motors fail the requirements of motor performance. A few batches of AFM were selected for testing. Each batch represents a different size (nominal power) of the same type of AFM.

The results of calculation of the 3D electrostatic field in a cylindrical tank provided with a system of vertical grounding rods are presented. The field intensities of the original tank without the grounding rods are very large, which may cause a spark discharge, even at a relatively small space‐charge density. The presented results involving the grounding rod system can be used to eliminate or reduce fire and/or explosion hazards.

Two approaches to 3‐D magnetic field calculations for low‐power special transformers are presented in the paper. The application of fast calculation procedures based on the finite difference method, to direct solving of the Poisson and Laplace equations is given. The calculated example deals with the three‐phase leakage transformer. On the other hand, the iterative solution of regularized integral equations used for calculation of 3‐D field distribution and integral parameters of leakage field in current transformer is also presented. The software packages developed by the authors are useful for computer‐aided design of low‐power special transformers.

The paper deals with the inductance calculation of air‐core coils system by means of 3‐D analysis of magnetic field of the coils with rectangular cross‐section. The possibility of mutual and self‐inductance calculation is presented. For magnetic field calculation, the Finite Difference Method with application of fast calculating procedures was applied. The method of calculation has been verified by experiments. The obtained difference between calculating and measurement results is equal to a few percent. The computer program is usefull especially for asymmetrical configuration of the coils.

The calculation of quasistationary magnetic fields and electrostatic fields of several objects is presented in the paper. In the range of the magnetic fields of coils and transformer systems parallelepiped calculation regions are assumed. In the range of electrostatic fields analysis of the field in tanks of different shape storing inflammable liquids was undertaken. Fast subroutines using finite differences [FDM] to calculate the field were employed. These subroutines are based on the Fast Fourier Transform (FFT).

This paper presents the field‐circuit analysis of a disc‐type torus DC motor with permanent magnets. Calculations of the magnetic field are carried out using the finite element method (FEM) in the 3D space. The integral quantities like the ripple‐cogging torque, back electromotive force, flux linkage, self and mutual inductances of the winding are analyzed. The electromagnetic torque is comparatively determined from the Maxwell stress tensor and co‐energy methods. Based on the 3D magnetic field calculations, the lumped‐parameter model of the tested motor is constructed, taking into account an electronic power converter as well. For comparison, various permanent magnet widths and teeth thicknesses of the stator core are considered. The torque pulsations are shown in simulations to be effectively reduced by an appropriate selection of a permanent magnet width on the pole pitch. Additionally, the efficiency of the tested motor can be significantly improved by a proper selection of the teeth thickness. The simulation results are verified with experimental data obtained from the slotless version of the motor prototype.

A brushless, permanent magnet, three‐phase disc‐type salient‐pole DC motor with co‐axial flux in the stator is considered. Electromechanical properties of a basic eight‐pole motor are compared with those for a 16‐pole one of the same volume, in order to contrast the two potential candidates for variable‐speed, low‐cost drives. As a basis of the comparative analysis, 3D FEM magnetic field modelling and circuit analysis considering an electronic commutator are employed. Increasing the number of poles results in unfavourable raising in the switching frequency. The eight‐pole motor construction has been shown in simulations to have higher efficiency and lower power losses than its 16‐pole counterpart.

Presents an approach to determine sources of cogging torque harmonics in permanent magnet electrical machines on the basis of variations of air‐gap magnetic flux density with time and space. The magnetic flux density is determined from the two‐dimensional (2D) finite element model and decomposed into the double Fourier series through the 2D fast Fourier transform (FFT). The real trigonometric form of the Fourier series is used for the purpose to identify those space and time harmonics of magnetic flux density whose involvement in the cogging torque is the greatest relative contribution. Carries out calculations for a symmetric permanent magnet brushless machine for several rotor eccentricities and imbalances.