Study On Measurement Method Of Two-dimensional Magnetic Properties For Silicon Steel Sheet Under Stress Loading

The main method for improving the performance of electrical equipment is to optimize the design of the core structure,and the premise of the optimization design is to measure and model the actual magnetic properties of the core material.The complex mechanical stress in core of electrical equipment,such as motor and transformer,not only produced in process of manufacturing or assembling but also occurred in the actual operation,which would affecting the magnetic properties.At present,the measurement method of magnetic properties under stress loading is still limited to the case of one-dimensional alternating magnetic field magnetization,and the direction of stress application is parallel to the direction of magnetization,which cannot meet the design needs of current electrical equipment.In order to obtain the magnetic properties of silicon steel sheet in actual working conditions more accurately,the measurement method of two-dimensional magnetic properties under the condition of stress loading for silicon steel sheet are studied in this paper.It focuses on the design and optimization of the excitation structure of the two-dimensional stress magnetic properties tester,the design and optimization of the biaxial stress-loading device,the construction of the stress magnetic properties tester platform and the experimental verification.The main content is as follows:(1)A novel two-dimensional excitation structure is proposed base on the one-dimensional single-sheet tester,which can meet the needs of two-dimensional rotary excitation and the stress loading.The magnetic circuit structure is simulated with finite element software.The shape of the sample is optimized to eliminate the influence of eddy current effect.The layered excitation winding is designed by calculation.(2)The B-H composite magnetic sensor combining the probe and the induction coil is designed and manufactured,and the coefficient of induction coil is corrected through the coil calibration experiment.Through the finite element simulation software,it is verified that the measurement accuracy of double-layer h-coil in the vertical excitation structure is higher than single-layer h-coil and the double-layer h-coil is designed and manufactured based on the simulation results.(3)A biaxial stress loading acquisition system is designed based on the new excitation structure.The feasibility of stress loading method is verified by Ansys finite element simulation,and the sample shape and fixture structure are optimized.The best control mode of motor is explored and determined through stretching experiment.No-magnetic aluminum material is used to manufacture the stress loading device,which can not only flexibly complete one-dimensionalalternating and two-dimensional rotating excitation,but also can apply two-directional tensile and compressive stress on the sample within a certain range.Tension sensor and strain card are used to display the stress.(4)Combined with the above work,the magnetic properties measurement system of silicon steel sheet under stress loading is built,which can measure the magnetic properties of silicon steel sheet under stress loading and achieve data collection and processing automatic.Based on the experimental system,the magnetic properties of silicon steel sheet under alternating magnetization were measured and compared with Epstein’s test data.At the same time,the one-dimensional alternating magnetic properties and the two-dimensional rotating magnetic properties under stress loading were measured and analyzed.