Translated Abstract
Hysteresis loop is an important characteristic loop which reflects the performance of magnetic materials. It is also important in the application of magnetic materials. Now, determining the reflection of hysteresis of magnetic materials accurately becomes more and more important in engineering design. For example, when analyzing the peculiarity of electromagnetic equipment, such as transformer and electromotor, accurate waveform is needed with considering the hysteresis of magnetic materials. Hence, in order to improve the precision and consider the magnetic hysteresis loss, the hysteresis loop of magnetic materials must be considered.
In this thesis, after considering the hysteresis of the core of transformers, research and simulation on single-phase shell-type transformer and three-phase transformer (three legs) are done. The main research contents are as following:
Firstly, the traditional J-A hysteresis model is introduced, of which the parameter expressions are deduced. And the traditional J-A hysteresis model is modified due to its non-physic solution at certain conditions. The equation set of the modified J-A hysteresis model is deduced. According to the measured hysteresis loop and magnetizing curve of the silicon steel sheet used in the single-phase shell-type transformer and three-phases transformer, the modified J-A hysteresis model is used to simulate its hysteresis loop. The change of hysteresis loop with the parameters’ variation is given.
Second, research and simulation on single-phase shell-type transformer are done. In the process, the eddy current loss is equivalent to the reflection of a nonlinear resistance, and the modified J-A hysteresis model is used. The simulation results are obtained under loaded condition. As to the unloaded single-phase shell-type transformer, the results of exciting current when consider hysteresis and neglect hysteresis are compared. As to the unloaded single-phase shell-type transformer the exciting currents and their harmonics are analyzed under two conditions: there are DC bias and there are not DC bias. The hysteresis loss of the core is calculated.
Finally, research and simulation on three-phase transformer (three legs) are done. In the process, the eddy current loss is considered, and and the modified J-A hysteresis model is used. The simulation results are obtained under loaded condition. As to the unloaded three-phase transformer (three legs), the exciting currents and their harmonics are analyzed under DC bias. The hysteresis loss of the core of each phase is calculated.
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