Analysis of Hysteresis Torque in a High-Speed Induction Motor

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Helsinki University of Technology | Diplomityö
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This work is carried out toward the development of high-speed motor design technology. The thrust of this research is twofold: First, to address the problem of modelling hysteresis in solid rotors whose iron made of magnetically semi-hard material. Second, to investigate the consequent hysteresis torque acting on the solid rotor of a high-speed induction motor. In hysteresis torque calculation, the accurate modelling of hysteresis loops is a priority should be superiorly handled. In the absence of a delicate straightforward method to model symmetrical minor loops with satisfactory results, a novel method for modelling symmetrical minor loops in hysteresis magnetic media is introduced. The proposed method is simple and effective. It takes on experimentally measured symmetrical minor loops combined with certain portions of the initial magnetization curve (the an hysteretic curve) to identify the Preisach distribution function. The numerical simulations and experimental results show that the presented method is much more adequate than other existing methods for predicting symmetrical minor loops in terms of both the modelling quality and the computation time. We also examine the hysteresis torque produced by a solid rotor of a high-speed induction motor. By applying an experimental method to an unloaded high-speed induction motor it has been possible to determine the change of power at small positive and negative slips. The change of power is believed to correspond to the hysteresis torque associated with the high-speed induction motor. Because of the two fundamental reasons that the rotor of the high-speed motor is solid and made of semi-hard ~ material, it is found that under certain measuring conditions the obtained hysteresis torque is relatively significant and approximately represents 2.2% of the rated torque.
Arkkio, Antero
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Saitz, Julius
high-speed induction motor, suurnopeussähkökone, solid rotor, massiiviroottori, semi-hard magnetic material, puolikova magneettinen materiaali, hysteresis modeling, hystereesi, the Preisach model, mallinnus, hysteresis torque, Preisach-malli, hystereesimomentti
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