Kemal Hot

Multi-Objective Optimization of Permanent Magnet Motor Using Taguchi Method

The performance of permanent magnet motor can be improved by optimization of its magnetic circuit. That can be achieved by means of finite element method in torque calculation and statistical analysis using orthogonal arrays and multi-objective approach. The magnetic field was calculated taking into account non-linear density and effect of current commutation. The electromagnetic torque was determined from magnetic vector potentials of moving conductors. The effect of change for every geometric parameter was particularly calculated. A fast improvement in shapes of the motor magnetic parts was achieved by an appropriate number of field and torque calculations.

Inequalities among quasi-arithmetic means for continuous field of operators

In this paper we study inequalities among quasi-arithmetic means for a continuous field of self-adjoint operators, a field of positive linear mappings and continuous strictly monotone functions which induce means. We present inequalities with operator convexity and without operator convexity of appropriate functions. Also, we present a general formulation of converse inequalities in each of these cases. Furthermore, we obtain refined inequalities without operator convexity. As applications, we obtain inequalities among power means.

Optimization of Permanent-Magnet DC Motors Using Orthogonal Arrays

The performance of permanent-magnet DC motor can be improved by optimization of its magnetic circuit taking into account important effects of magnetic density distribution in motor air-gap and neutral zone. The optimization can be achieved by means of finite element method in field and torque calculation and statistical analysis using orthogonal arrays. The electromagnetic torque as an objective function was calculated directly from magnetic vector potentials of moving conductors as an average value through a slot pitch shift. A fast improvement in shape of some motor parts was achieved by a very limited number of field and torque calculations. The optimization results verified this approach in modeling of DC motors with permanent magnets.

Shape optimization of GIS insulator barrier

A gas insulated substation (GIS) barrier with conical insulators from a cast epoxy resin is optimized to withstand AC and DC stresses. The field distribution across insulators with long creepage path and field distortion due to the deposition of charge on the insulator surface is calculated on a parametric geometry model by finite element techniques. The shape of the insulator and surrounding electrodes was improved fairly quickly using a direct search method with constraints. The results of optimization were verified by standard measurements on high voltage insulators in SF6 gas.

Design of GIS insulators including small metal particle influence

The influence of accidentally left metal particles inside high voltage gas insulated switchgear was investigated using 3D finite element method for transient electric field with slightly non‐linear permittivity and floating potential of moving particles.

Inverse problem of voltage over electrostatic shield gap in helical transformer windings

Multi-conductor transmission line model of a helical winding for an analysis of the very fast electromagnetic transients will include the lumped voltage between the edges of the open electrostatic screen, previously found to be responsible for experimentally found anomalous distortion of the travelling waves. Contrary to the former model with distributed voltage and axial symmetry, the new model requires parameters beyond those of classical theories of wave propagation in transformer windings. The additional parameters are found by matching the simulated voltage transients with the experimental results.