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The estimation and calculation of the acoustic sound of electric machinery is of high interest. Various approaches have been presented relying either on analytical or on numerical models. In general, the analytical models are based on the electromagnetic-field theory and the results are compared to measurements. Numerical models allow for the separation of different exciting forces stemming from various effects. In the studied case of an induction motor with squirrel-cage rotor three effects are taken into account in the analytical model: the fundamental field, saturation, and eccentricity. The numerical analysis is applied for the analysis of acoustic sound of an electric machine. Nevertheless, the numerical results have to be verified. Hence, they are compared to the physically based analytical results. The radiated noise depends directly on the surface's deformation of the machine. Therefore, the analysis is focused on the structure-dynamic vibrations. The combined analysis presented here, allows for the reduction of vibrations and noise optimizing the coupling of stator and housing. Here, an induction machine (IM) with squirrel-cage rotor is studied. Its housing is mounted with six spiral-steel springs to the stator. With the presented method the impact of different numbers of springs is analyzed.
In this paper a phenomenogical energy-based harmonic ferromagnetic material model is presented which considers time-dependent hysteresis losses as a part of the material characteristic. The model is based on the effective reluctivity concept and can be applied to simulate hysteresis losses of electromechanic devices. The hysteresis losses of a C-Core are simulated and compared to the results of an iron loss estimation by loss curves.
The evaluation of the electromagnetic, structural and acoustic behavior of an induction machine is computationaly expensive. Optimization algorithms are therefore not applicable.
This papers demonstrates that the methodology of design of experiments (Taguchi method) has been successfully applied for the multi-objective optimization of such multiphysics devices. A significant improvement of the machine performances can be achieved with this approach after only a few evaluations of the coupled FE model
Non grain-oriented electrical steel has an inherent anisotropy, which is normally neglected in the calculation of electrical machines. Moreover, the magnetic anisotropy is usually measured in small material samples. Due to the cutting effect, the magnetic anisotropy in the machine is not the same as in the sample. In this paper, the magnetic anisotropy is considered as a global problem. A method to measure it is presented and its influence on the electromagnetic and acoustic behavior is considered through the example of an induction motor.
Numerical Calculation of Iron Losses in Electrical Machines with a modified Post-Processing Formula
(2007)
The motivation of this analysis is the need of high efficiency and high power density permanent magnet synchronous motor (PMSM) drives for use in electrical vehicle power trains. It is clear that the chosen electrical steel for the lamination stack plays an important role, but proper quantification is missing. The purpose of this paper is to formalize the problem of selecting the optimal steel grade for the construction of PMSM’s. This question is important to steel producers, not only for helping customers selecting the most appropriate existing grade for their application, but also for defining the strategic orientation of the further R&D of enhanced electrical steel grades. The notion of steel efficiency is defined and, after describing the FE implementation of iron loss models, a methodology for material optimisation is proposed.
The estimation and the calculation of the acoustic sound of electric machinery are of particular interest nowadays. Various approaches have been presented, relying either on analytical or on numerical models. The analytical models presented here are based on the electromagnetic-field theory. Numerical models are applied to derive the exciting forces stemming from various sources and effects. The numerical results have to be verified. Hence, they are compared with the physically based analytical results. The radiated noise depends directly on the surface deformation of the machine. Therefore, the analysis is focused on the structure-dynamic vibration. The combined analysis presented here allows for the reduction of vibration and noise, optimizing the coupling of the machine's stator and housing. The studied induction machine's housing is mounted with six spiral-steel springs to the stator. With the presented method, the impact of different numbers of springs is analyzed exemplarily.
Purpose - The purpose of this paper is to describe how a minimisation of cogging torque is performed with respect to the non-ideal manufacturing process, aiming at a robust design of the studied machine, focusing on magnetisation faults and the use of different qualities of the permanent magnet material. Design/methodology/approach - The applied methodology is a combination of design of experiments and finite element analysis to minimise the cogging torque of the estimated machine. Different qualities of the permanent magnet material are investigated by a stochastic analysis. Findings - A robust design of the machine is achieved, which is verified by a stochastic analysis. Furthermore, this analysis shows the strong influence of the magnet quality on the cogging torque. Practical implications - This paper provides a method for a machine design which is robust against non-ideal manufacturing and an approach to prove the use of a bad quality for a possible reduction of the fabrication costs. Originality/value - This paper gives a close insight on how to investigate non-ideal manufacturing and in particular its influence on the cogging torque.
In this paper, a phenomenological energy-based material model for ferromagnetic materials under harmonic conditions is presented. The model is based on the concept of a complex effective permeability and an accurate representation of energy is adopted as identification criteria. The material model is implemented in a time-harmonic finite element model, which allows to solve for the loss characteristics of electromagnetic devices. Identification is based on measured hysteresis loops and no additional fitting parameters are required. Hysteresis losses in a ferromagnetic C-core and a ferromagnetic torus are simulated and compared to the results obtained by means of tabulated loss characteristics.
For the reduction of the cogging torque of permanent-magnet synchronous machines several approaches are known. But cogging torque predictions for arbitrary types of machines using the same approach are still troublesome and imprecise. Therefore, a fast optimization process is developed and presented in this paper. Here, the combination of both numerical and analytical simulation results in such a fast method
Non grain-oriented electrical steel has an inherent anisotropy, which is normally neglected in the calculation of electrical machines. Moreover, the magnetic anisotropy is usually measured in small material samples. Due to the cutting effect, the magnetic anisotropy in the machine is not the same as in the sample. In this paper, the magnetic anisotropy is considered as a global problem. A method to measure it is presented and its influence on the electromagnetic and acoustic behavior is considered through the example of an induction motor.