Vector Magnetic Properties Oriented to Magnetic Field Analysis

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Numerical simulation of magnetic fields requires a proper material modeling as well as a robust method of discretization of governing equations. Only a robust discretization is not enough to get higher accuracy and to improve design strategy. Recently, the material modeling receives large engineering attention. In this project, magnetic anisotropy (vector magnetic property) of electrical steel sheet, which is used as a material for principal magnetic path in electrical machine, is discussed. A standard method of measurement by means of a double-excitation type of single sheet tester is investigated and a modeling method for anisotropy is developed based on the finite element formulation. Then it is applied to the analysis of typical electrical machines for verification. The contents discussed are as follows.(1)Construction of a measuring system, and examination of measurement accuracy and its improvement,(2)Measurements of vector magnetic properties of various electrical steel sheets,( … More 3)Development of an approximation method of vector magnetic property, its verification by using numerical simulation method, and its stabilization and speedup,(4)Application to three-phase transformer core and interior permanent magnet motor.Regarding to a method of measurement, magnetization properties up to 2 T can be measured for various kinds of electrical steel sheets with different degree of anisotropy Reproducibility of the measurement is within about ±3%, which is similar to that for ordinary 1-D measurements. Therefore, the proposed method of measurement seems to be fairly useful.Regarding to numerical simulation, a method of modeling anisotropy using normal magnetization curves are established. Its stability for nonlinear iterative analysis is nearly equivalent to ordinary calculations without taking account of anisotropy because of the introduction of a line search technique. Robustness of the method is verified by applying it to the analysis of typical electrical machines using recently developed cube-textured electrical sheets. Less