Study In The Post-assembly Magnetization Method Of Permanent Magnet Motors

With the development of Rare earth permanent magnetic material,Permanent magnet motor has been widely applied in various fields. As an important part of permanent magnet motor, the magnetizing system has been put forward higher requirement, post-assembly magnetizing method has the characteristics of convenient assembly and high efficiency etc, so it has great research value and broad prospects. For the conventional permanent magnet motor’s permanent magnet, the traditional before-assembly magnetizing method is usually be used for magnetization, but after magnetization, powerful electromagnetic force will make it difficult to assemble the permanent magnet and the rotor. This paper presents a new method of magnetizing which is using the coil wrapped around the outside of the magnet to provide the magnetizing field, the paper is focusing on the method of theoretical calculation and experimental research.First of all, this paper introduced the basic pulse current magnetizing technique of magnet, and discussed magnetizing methods of permanent magnet motor, compare to the magnetizing method that using the armature winding to provode magnetizing field, the paper focus on magnetizing current and energy to introduce the new magnetizing method.Secondly, this paper analyzed the multi-physics fields coupling processes of electromagnetic magnetizing including circuit, magnetic field, temperature field and structure field. And established the magnetizing method system in the finite element numerical calculation model, including 2-D FEM numerical model of magnetizing with COMSOL Multiphysics software and 3-D FEM model with CEDRAT FLUX software. The magnetizing field and magnetizing coil stress and temperature are simulated and analyzed, and then a magnetizing coil winding is make out from design.Thirdly, some experiments of the new magnetizing method were researched, the experiments were divided into two parts. One part is the basic research of the characteristic of permanent magnet when under magnetizing or demagnetizing. Another part is using the coil just design to do unipolar magnetization and demagnetization experiments, the charge and basic experimental research so as to verify coil magnetization and demagnetization effect and heating, stress, etc. The experimental results show that the design can realize an excellent magnetizing effect.Finally, on the basis of above mentioned, magnetizing system scheme of the motor is designed, including magnetizing parameters selection and optimization, motor magnetizing power solutions. After calculation, demonstration and experimental verification, the new post-assembly magnetizing method of permanent magnet motor is efficient, convenient assembly, under the method, magnetizing and demagnetizing can be done without disammbly, the method will have important applications in the future.