| There exists multi-physics coupling such as magnetic field,temperature field,and structural force field during operating process of electrical devices like electrical machine and transformer.In order to accurately carry out performance analysis in the design stage,it needs not only to study method of high-performance numerical analysis for multi physical field coupling,but also requires material characteristics under influence of external physical factors.Electrical steel sheet known as silicon steel sheet is one of the most widely used soft magnetic materials in the world.It is mainly used as core material of rotating motor and transformer.Under the complex magnetic field,the magnetic properties of silicon steel sheet show obvious hysteresis,eddy current,and anisotropy.In addition,during manufacturing and operation of electrical machine such as motor and transformer,the grain in silicon steel sheet has a certain degree of plastic deformation due to mechanical and thermal stresses.Its magnetic properties will also change.Therefore,in the design and optimization of modern electrical equipment,it is particularly important to obtain magnetic characteristics of silicon steel under complex magnetic field and stress.There are many technical problems in the design of complex magnetic properties measurement technology of silicon steel sheet.This thesis mainly studies stress loading method in the measurement of magnetic properties,and completes measurement of alternating and rotating magnetic properties of oriented and non-oriented silicon steel sheet by using the complex magnetic properties measurement device considering stress.The main contents are summarized as follows:First of all,in order to improve the area and saturation degree of uniform magnetic field,a measuring device with circular yoke structure is designed and compared with the traditional planar structure and three-dimensional excitation structure.The stress required in the measurement process is realized by piezoelectric fiber sheet.The piezoelectric fiber sheet is affixed on upper and lower surfaces of silicon steel sheet.Driven by the adjustable voltage,the piezoelectric fiber sheet will lead the silicon steel sheet to a certain degree of deformation.The deformation can be adjusted by the driving voltage to realize the tensile(compressive)stress loading.Secondly,in order to measure complex magnetic properties of silicon steel sheet,the probe method and double compound H-coil method are utilized to detect magnetic induction intensity B and magnetic field intensity H respectively.For the probe method,by collecting induced voltage between probes,the waveform of the internal magnetic induction intensity of the silicon steel sheet can be calculated based on electromagnetic induction.For the double compound H-coil method,according to the principle of continuity of magnetic field on the interface of different mediums.The magnetic field intensity waveform inside the silicon steel sheet can be obtained by synchronously measuring the magnetic field intensity at different positions on the surface of the sample.The obtained magnetic induction intensity B signal and magnetic field intensity H signal are very weak,which can be amplified and isolated by the isolation amplifier and collected by analog input channel of data acquisition card to upper computer for further processing.Finally,the magnetization trajectory and iron loss of non-oriented silicon steel sheet(35W470)and oriented silicon steel sheet(30QG120)under alternating magnetization and rotating magnetization are measured by using a new type of complex magnetic characteristics measuring device for electrical steel sheet under stress loading.According to the measurement results,the complex magnetic characteristics of these two kinds of silicon steel sheets under different stress loading conditions and magnetization conditions are summarized. |
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