Simulation Research on the Service Performance of NdFeB Permanent Magnets for Permanent Magnet Motors

Abstract

Electrical motors is the equipment that convert the electrical energy into the mechanical energy. And they are the main source of power for modern industry application. However, the energy efficiency level of the ordinary stepper motors is low, and the rare earth permanent magnet motors are needed to replace them for the needs of higher energy efficiency in the new era. As an important rare earth functional material, rare earth permanent magnet is the most widely used magnetizing material for permanent magnet motors at present. Its comprehensive magnetic performance is excellent, but its temperature coefficient is relatively high. When it is demagnetized by an external magnetic field at high temperature, it is easy to cause irreversible demagnetization, resulting in the reduction of motor torque performance and even the scrapping of the whole machine. Therefore, it is necessary to understand its demagnetization characteristics to effectively overcome or slow it down. Secondly, the loss generated by the permanent magnets is one of the important sources of the eddy current loss of the rotor part, and the in-depth understanding of it will help to reduce this kind of loss. In addition, the radial force generated acting on the stator teeth will cause the teeth to swing, which is also an important source of motor vibration and noise. It is necessary to conduct in-depth research on it. Aiming at the above three aspects, this paper conducts in-depth and systematic analysis and research through simulation calculation. It is very significant to improve the service performance of rare earth permanent magnets for the interior permanent magnet motors, and it is also a beneficial fundamental academic exploration. In this paper, the performance of the permanent magnet is analyzed and designed. It is known that the anti-demagnetization ability of the permanent magnet decreases with the continuous increase of temperature, and the ability of the permanent magnet to generate a magnetic field also decreases. This is mainly due to the internal material of the permanent magnet, which is also our most concerned permanent magnet demagnetization mechanism. The loss of magnetism of the permanent magnet will induce the motor fail to meet the torque output we need, and it will not be able to continue to meet the service lifetime requirements. Due to the permanent magnet demagnetization, the motor needs a higher current to drive, and the higher current will bring higher heat energy and cause the motor to heat up seriously. Therefore, the superposition will shorten the lifetime of the motor and eventually lose its working ability. We conduct research on these issues to protect and prevent the permanent magnets from loss of magnetism.