Measurement and Analysis of Hysteresis Loss of Nd-Fe-B Permanent Magnet under Superheated Loss of Magnetism

Rare earth permanent magnet materials, such as NdFeB, are widely used in permanent magnet motors because of their good magnetic properties, low price and good mechanical properties. The harmonic magnetic field in the motor will cause permanent magnet loss, which will lead to permanent magnet overheating loss of excitation and affect the stable operation of the motor. In this paper, through the design of permanent magnet comprehensive magnetic characteristics test device, quantitative application of AC magnetic field, it is found that under low frequency, saturation magnetization of NdFeB will appear obvious hysteresis phenomenon. In this paper, the hysteresis loss of NdFeB material under the condition of overheating loss of excitation is measured quantitatively and the magnetic characteristics are analyzed. It is found that the NdFeB with overheated loss of magnetism will produce obvious hysteresis loss.The test results show that the permanent magnet will lose its magnetism when it runs at high temperature for a long time, and the hysteresis loss of the permanent magnet will increase gradually, and even the hysteresis loss will be higher than the eddy current loss under certain conditions. This shows that the hysteresis loss of the permanent magnet will accelerate the failure of the permanent magnet, and in some cases is the main reason for the loss of excitation.