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The paper presents an optimized design of a low mass brushless DC (BLDC) permanent magnet motor for propulsion of an ultra light aircraft. The optimization has been carried out using Differential Evolution algorithm implemented in Matlab combined with SPEED and MotorCAD software packages for electromagnetic and thermal modeling of the BLDC motor using ActiveX technology. The credibility of the models created with SPEED and MotorCAD has been confirmed by comparing the results of simulation and measurement performed on a 12 kW synchronous permanent magnet motor available in the laboratory. The goal of the optimization has been to minimize the weight of the motor under condition that the motor delivers rated power of 15 kW at rated speed of 3000 rpm with hot-spot temperature not exceeding the temperature limits of class F insulation (155 °C). Two optimal BLDC motor designs with slot/pole combinations 12/10 and 18/16 have been obtained. The motor with 18 slots and 16 poles yields the highest torque density with the lowest mass of active parts (copper+laminations+magnets) of only 5.1 kg. Source


Opetuk T.,University of Zagreb | Tosic M.,University of Zagreb | Dukic G.,University of Zagreb | Solaja J.,KONCAR Distribution and Special Transformers Inc
International Conference on Industrial Logistics, ICIL 2014 - Conference Proceedings | Year: 2014

Nowadays many storage systems exist, requiring proper analysis for a decision which one to implement in a real case. This professional paper presents cost-based analysis of one case study, aimed to evaluate implementation of storage system with moveable pallet racks. Main advantage of moveable racks, storage space saving, justified higher investment costs. Second part of paper illustrates implementation process of selected variant in practice. Copyright © FSB, Zagreb, Croatia, 2014. Source


Opetuk T.,KONCAR Distribution and Special Transformers Inc | Zolo I.,KONCAR Distribution and Special Transformers Inc | Dukic G.,University of Zagreb
Journal of Industrial Engineering and Management | Year: 2010

Due to climate change and the increase in environmental awareness in the world, the concept of Green Supply Chain Management appeared. The concept is aimed at the reduction of several elements: energy, materials, the pollution and the waste in production and logistics processes. Power networks are a part of a supply chain of production and distribution of electrical energy, and similar principles of greening could be applied. Currently, the losses within the distribution networks in the whole world are between 3.7 to 26.7% and they primarily occur due to the losses in the conductors and the losses within distribution transformers. After an overview of the losses in the power networks and related CO2 emission, some solution of how to reduce the above mentioned losses are given. Such improvements, apart from the significant economic repercussions, in the same time represent non-negligible greening element in the area of electrical energy distribution. © Journal of Industrial Engineering and Management, 2010. Source


Sitar I.,KONCAR Distribution and Special Transformers Inc | Janic Z.,Koncar Power Transformers Ltd. | Cucic B.,KONCAR Distribution and Special Transformers Inc
COMPEL - The International Journal for Computation and Mathematics in Electrical and Electronic Engineering | Year: 2012

Purpose - The purpose of this paper is to determine the external magnetic field density of the traction transformer for EMU and to find the model for its computation. Design/methodology/approach - The magnetic flux density in the surrounding region of the traction transformer was modeled and calculated using FEM. The transformer was modeled in a way that tank, clamps and current sources were taken into account. Most frequent operating modes for the basic 50 Hz current harmonic, and most represented higher harmonic of 1,950 Hz loading current, were analyzed. Findings - Matching calculated and measured values were obtained on the finished transformer. The developed calculation has proved to be a useful tool for the stray field calculation outside this type of transformer. Calculated values of the flux density are lower then the maximum permitted values defined by the DIN VDE 0848 standard. Originality/value - This paper presents a study of calculation compared to measurement of magnetic field density outside an oil immersed transformer. © 2012 Emerald Group Publishing Limited. All rights reserved. Source

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