Research And Measurement Of High Frequency Rotational Magnetic Proprieties Of Nanocrystalline Alloys

In recent years,with the rapid development of power electronics and power grid technology,electrical equipment has shown a trend of high frequency and miniaturization.However,due to the lack of deep understanding of the magnetic characteristics of new highfrequency materials,high frequency electromagnetic equipments with good performance are limited.Nanocrystalline and amorphous alloys as new type of high frequency soft magnetic materials,compared with ferrite,have higher permeability and higher saturation flux density,but due to the lack of two-dimensional magnetic properties and rotating experimental data,their application in high power applications have been limited.Based on the National Natural Science Foundation of China,a series of studies have been carried out,with emphasis on the developing the high frequency rotating magnetic properties experimental system for nanocrystalline alloys.The main innovative works are summarized as follows:(1)Based on analysis of the physics properties of nanocrystalline alloys and the state of art of soft magnetic materials characterization,the necessity of two-dimensional high frequency rotating magnetic properties measurement for nanocrystalline alloys has been discussed.Four kinds of magnetizing structures have been analyzed and compared based on FEM calculation.It is found that the square sample magnetizing structure has better homogeneity.Based on the calculation results,a newly double-C magnetizing structure has been proposed especially for nanocrystalline soft magnetic materials which can extend the rotational magnetic properties measuring frequency up to 10 kHz.(2)To improve the homogeneity of magnetizing the sample,magnetic shielding structure has been considered.Because the nanocrystalline alloys are super thin and fragile after annealing,a newly compact two-dimensional hysteresis vector sensor has been carried out and calibrated.After that the vector and rotating magnetic properties of nanocrystalline alloys have been measured.(3)A measuring system based on NI PXI platform for measuring the high frequency magnetic properties of nanocrystalline alloys has been developed.A waveform control method based on time domain waveform period voltage control is proposed,which improve the efficiency of the implementation process,reduce the requirement of measurement for high frequency magnetic properties of the system hardware.(4)Varies of experiments of measuring high frequency alternating and rotating magnetic properties of nanocrystalline alloys have been performed.It is found in the testing results that the nanocrystalline alloys have some transverse anisotropy properties: When flux density is low,the permeability of casting direction significantly higher than that in the transverse direction,which cause the losses on the transverse direction are higher than losses in the casting direction;When the flux density increased,the anisotropy of nanocrystalline alloys changed: the transverse direction has higher permeability.In rotational magnetization conditions,similar results are obtained.With the increase of magnetic flux density,the anisotropy changed.What's more,when the magnetization goes to saturation,the rotational losses will decrease.