Design and Optimization of Fractional Kilowatt or Medium Power Electrical Machines

Dear Colleagues,

How can the role of electric motors in the contemporary technological era be emphasized? With tangible data since it is estimated that around 43 to 46 percent of the world's electricity is consumed by propulsion systems with electric motors, of fractional kilowatt or medium power (0.75 kW - 375 kW) having the largest share. Induction motors are dominant, while lighting systems are the second-largest consumer of energy.

Like many other devices, electrical machines require modeling of a series of coupled physical phenomena, depending on the material properties. We are also dealing with several requirements regarding their properties, such as obtaining the highest value of electromagnetic torque or power output, high efficiency in the case of several machines resulting from international standards, low noise levels, and, very importantly, low production costs. The production process and therefore the design of electrical machines are also influenced by several factors related to the production process, e.g., the automation of winding preparation and placement. The manufacturing process also influences the properties of particularly magnetic materials, for instance, the impact of the punching method and the use of heat treatment. Since an electric machine is the basis of every electric drive, maximizing its efficiency is clearly a priority. Currently, both analytical and numerical models are used in electric motor modeling. They allow us to determine, with enough accuracy, the electromagnetic parameters of these motors as well as their operational characteristics, for various nominal power and load conditions. Known numerical models of electric motors—like those amenable to the finite element method—consider the impact of certain technological processes on motor parameters while existing analytical models assume that implemented technology does not introduce any additional phenomena affecting the motor parameters. In this respect, the impact of technology at the stage of electric motor modeling is often considered by introducing correction factors, heuristically identified after measurement results are obtained for different groups of motors with different frame sizes.

Progress in sophisticated optimization methods combined with effective numerical and analytical modeling techniques introduce a superior quality into the design process. However, it is necessary to consider several, sometimes very severe, technological and economic restrictions, which often prevent the use of optimal design solutions in practice. A new additional constraint introduces the environmental footprint that exceeds the criteria of efficiency. More often than not, conflictual design criteria have to be simultaneously met; in this case, multiobjective optimization methods help to find the best compromise among conflictual objectives. The use of quick optimization methods, however, can improve the design parameters of electrical machines, taking into account new materials and technologies, and, very importantly, conditions of strong competition on the market; this way the time it takes to introduce new solutions can be substantially shortened, also thanks to the possibility of abandoning the construction of a number prototypes.

We invite you to submit articles on both theoretical and algorithmic aspects of optimization, but with a clear application in our area of interest as well as examples of design optimization considering new technologies, e.g., new magnetic composites, additive manufacturing, and 3D printing.

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• Electrical machines
• Optimization methods
• Rapid Electric motor design
• Quick optimization methods
• Technology impact
• Electrical machines modeling for optimization
• Multiobjective optimization methods
• New materials and technologies