Volume 3 Issue 3

Authors: Reza Namazi Nanekaran; Esmail Fallah Chulabi

Abstract: The use of the Brushless DC Motors (BLDC) for industrial and transportation applications has been developed increasingly. These motors have many advantages such as good efficiency and high torque to weight ratio but the torque pulsation is the most concern of these motors. Pulsating torque can be considered as the result of two components, torque ripple and cogging torque. Torque ripple is the result of the overlap between the feeding time of the two adjacent phases while cogging torque is the result of the variable magnetic reluctance. In this paper, changing two parameters including embrace (pole arc to pole pitch ratio) and offset (displacement of the pole arc center), cogging torque was calculated using Finite Element Method (FEM). An Artificial Neural Network (ANN) was used to interpolate between the limited results of the time-consuming Finite Element Analysis (FEA). Two optimization methods including Particle Swarm Optimization (PSO) and Imperialist Competitive Algorithm (ICA) were used to find the best design parameters in which the torque ripple reaches the minimum. Finally, the optimum designs were validated by FEA.

Keywords: BLDC; FEM; ANN; PSO; ICA


Authors: Alexander V. Strizhachenko

Abstract: This work is the continuation of series of works on research of physics of resonant phenomena in waveguide junctions of various cross-section and to their using for measurement of electric characteristics of materials. The comparative characteristic of eigen Q-factor waveguide junctions of various cross-section section has been given: cylindrical - radial waveguides, rectangular - rectangular waveguides, cylindrical – rectangular waveguides. The recommendations on using of concrete type of waveguide junctions for measurement of dielectric losses of the certain materials has been given.

Keywords: Waveguide Junctions; Permittivity; Dielectric Losses