Grant-in-Aid for Scientific Research (B)
|Allocation Type||Single-year Grants|
|Research Institution||Okayama University|
TAKAHASHI Norio Okayama University, Department of Electrical and Electronic Engineering, Professor, 工学部, 教授 (40108121)
TAKABAYASHI Hirofumi Sumitomo Special Metals Co.Ltd., Magnet Product Section, Section Chief, マグネット製品課, 課長(研究職)
OHASHI Ken Shin-Etsu Chemical Co.Ltd., Magnetic Materials R&D Center, Project Manager, 磁性材料研究所, 室長(主任研究員)
MURAMATSU Kazuhiro Okayama University, The Graduate School of Natural Science and Technology, Resea, 大学院・自然科学研究科, 助手 (30263627)
FUJIWARA Koji Okayama University, Department of Electrical and Electronic Engineering, Associa, 工学部, 助教授 (20190093)
|Project Period (FY)
1995 – 1996
Completed(Fiscal Year 1996)
|Budget Amount *help
¥2,900,000 (Direct Cost : ¥2,900,000)
Fiscal Year 1996 : ¥800,000 (Direct Cost : ¥800,000)
Fiscal Year 1995 : ¥2,100,000 (Direct Cost : ¥2,100,000)
|Keywords||Permanet Magnet / Magnetic Characteristic / Standard Measuring Method / Magnetic Field Analysis / Demagnetizing Factor / Hysteresis / 強磁場|
The basic investigations for preparing the draft about IEC standard method of for measuring magnetic characteristic of strong magnet are carried out. The results obtained can be summarized as follows :
1. Development of Method for Analyzing Magnetic Field in Non-Oriented Materials Taking into Account Hysteresis Characteristics
In order to calculate demagnetizing factor for permanent magnet, the method for analyzing magnetic field in non-oriented materials taking into account hysteresischaracteristics is developed. In this method, M-B loop is used as magnetic characteristics and the direction of magnetization is assumed to be the same with that of flux density.
2. Development of Method for Analyzing Magnetic Field in Electric Machine Magnetized by Discharging Current of Capacitors
If the pulse width of the open magnetic circuit method is small, the error of measured magnetic field strength due to the opposing magnetic field produced by he eddy current is not negligible. In order to investigate the effect of the pulse width on the accuracy, the finite element method, in which the magnetizing current is unknown, is developed. The validity of the method is verified by comparing the calculated results with measured ones.
3. Factors Affecting Accuracy of Measurement
(1) Shape of specimen
The optimum shape of specimen is that the height of magnet is the same with the diameter from a standpoint of constant demagnetizing factor.
(2) Magnetic characteristics of specimen
The variation of demagnetizing factor of Nd-Fe-B magnet is larger than that of Sm-Co magnet near the coercive force.
(3) Manufacturing deterioratration
The effects of manufacturing deterioratin of side surface of specimen on the demagnetizing factor is larger than that of edge surface. This effects is large when the specimen is long.
(4) Eddy current
The change of magnetic field dB/dt produced by the pulse magnet should be less than 80T/ms in order to obtain 3% accuracy.