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In this paper, a numerical model describing the heat transfer and air flow inside and outside the casing of the permanent magnet brushless direct current (PM BLDC) motor is presented. In the model, a conjugate heat transfer including the heat conduction with heat sources in windings, magnets, bearings, natural and forced convection and radiation phenomena within internal and external air domain were analysed. The complex geometrical model included windings, a magnet circuit, a rotor with neodymium magnets, a PCB electronic plate, plastic covers, internal air between solid parts as well as a portion of the external air. The validation process of the developed model was realised on the basis of the velocity and temperature fields. The experimental data were recorded by 7 constant temperature anemometers at 4 levels above the motor housing, Laser Doppler Anemometry sensors in two axes inside the rear portion of the motor and 25 thermocouples fixed inside and outside the motor. The experimental and numerical tests were performed for 4 motor loadings and 3 rotational speeds. The average temperature error for the internal point was of 9 K, while that of the external points was of 2 K. The velocity field was very well predicted close to the housing wall in terms of horizontal and vertical components. A slightly worse agreement was found for the vertical component, especially in the vicinity of the shaft. The results were consistent for all the considered motor loadings and rotational speeds. [ABSTRACT FROM AUTHOR]

This paper presents a finite-element-based simulation methodology to improve on multiscale modeling and analysis limitations of power electronics development. The method utilizes homogenization and nonmatching grid concepts to offer a high degree of flexibility and reduce computational effort. The applied homogenization method provides effective material properties to realize full-chip modeling performance without the need to model geometric details. The concept of nonmatching grids allows the inclusion of a subregion with substantially finer mesh than its surrounding regions. This allows the flexible integration of micrometer scale geometries with a high degree of detail within the full-chip model. Both concepts are thoroughly introduced and an application to a state-of-the-art power electronics semiconductor technology is presented. This paper focuses on electrothermal interaction and is experimentally verified on a dedicated test structure. The presented results provide electrothermal insights in current power electronic technologies and emphasize their potential to further improve the robustness and reliability of next generation technologies. [ABSTRACT FROM PUBLISHER]

The paper presents analytical and numerical model calculation results of the temperature distribution along the thermal flow meter. Results show a very good conformity between numerical and analytical model. Apart from the calculation results the experimental investigations are presented. The author performed the test where a temperature of duct wall surface was measured. The relation between mass flow rate in terms of the duct surface temperature difference was developed. [ABSTRACT FROM AUTHOR]