Permanent magnets, especially Nd-Fe-B magnets, are very important engineering elements that are widely used in many applications. The detailed design of electrical and electronic equipment using permanent magnets requires the precise measurement of magnetization characteristics. High pulsed magnetic fields can be used to measure the magnetization characteristics of permanent magnets in the easy and hard magnetization directions. Errors influencing the measurements stem from the relationship between the tested material, pick-up sensor configuration, and excitation coil. We present an analysis of the effect of the sensor construction on the accuracy of the measurements of the material's magnetic properties. We investigated the coaxial and series types sensor configurations.
2-D vector magnetic properties accurately represent the magnetic properties of various kinds of electrical steel sheets, because they can represent an alternating magnetic field in any direction and a rotating magnetic field by using the relationship between the flux density vector B and the field strength vector H. E&S modeling is proposed as a method for representing 2-D vector magnetic properties in magnetic field analyses. However, the E&S modeling used in magnetic field analyses is very time-consuming. To solve this problem, we propose complex E&S modeling on the assumption that both the flux density and field strength waveforms are sinusoidal. We carried out FEM analyses taking account of complex E&S modeling. Finally, we compared the analyses results considering complex E&S modeling with those of conventional E&S modeling, and made clear the efficiency of complex E&S modeling.
The measurements of the coercive force (Hc) of magnets are very difficult to determine as a function of the true effective fields in samples with arbitrary shapes. In this study, we tried to obtain the exact coercive force, M-H curve in high and high pulsed magnetic fields up to 20T by using a double-core pick-up. The values of Hc were found over-estimated more than 20% for the Nd-Fe magnets in comparison with those announced by the company, which coincided well with the numerical simulations by using JMAG. The two samples cut along easy and hard axis showed the same saturation magnetizations, reflected by the isotropic microstructure of the raw material.
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