Magnetic Field Analysis And Design Of Coreless Disk Permanent Magnet Motor

Disk permanent magnet motor is a kind of axial flux motor which developed fastly as high performance servo motor recently. It has many advances such as small volume, low weight, close structure, low moment of inertia of rotor, steady operation and so on. It has been used widely for military affairs, spaceflight, agriculture and daily life as new drive device. The different air gap structures of disk coreless PM motors have been made, specially, disk coreless PM motors of average air gap structure, wedge airgap structure and multi-airgap structure have been concerned widely as a significant research project in recent years.Disk permanent magnet motor is a new sort of permanent magnet motor. So this paper introduced the classification of permanent magnet motor, the present development and the application. And this paper analyzed the performance of the permanent magnetic material and selection criterion, and then we chose Nd2Fe14B as the permanent magnetic material. Secondly, the structure and the parameter calculation of disk permanent magnet motor are also discussed. After that, a coreless disk permanent magnet motor which adopted a one-rotor-two-stators configuration was presented. Specailly, the permanent magnetic material is fixed on the both rotors. Due to the permanent magnet motors with the general permanent magnet arrangement have numerous magnetic flux in yoke and the leakage of magnetic flux is more serious, the text developed a disk coreless PM motor based on Halbach. Halbach permanent magnet arrangement can greatly reduce the magnetic flux in motor’s yoke department. In addition, the struction could reduce the production cost and improve motor’s dynamic performance. Motor’s quality and inertia will decrease. Halbach permanent magnet arrangement has three types in terms of variable angles. This paper analyzed the variable Halbach permanent magnet arrangement by the finite element analysis software Ansoft. Then, we proved the60°arrangement is the most suitable one for simplifying the production of the PM. As the theory of the electromagnetic field for studying the motor is the most important theory, and finite element analysis software Ansoft is the most common tool in the theory of the electromagnetic field, we introduced the theory of the electromagnetic field and the finite element analysis software in the forth section. In the last section,2D and3D modeling simulations of coreless disk PM motor were proposed with the finite element analysis software Ansoft. In the paper, the simulation was presented for the armature magnetic field.The magnetic lines were compared when the disk motor worked in load and unload situation. It could be seen that the two cases do not change a lot. In the3D modeling simulation, the selection of air cover to the performance of motor has very big effect. So diverse air-gap flux density was simulated in the paper, and flux density curve showed that at the condition when the air cover size was three times of peripheral size for motor, the performance was better. Finally the air-gap flux density in different radius was simulated. The air-gap flux density amplitude in average radius was the largest one.