Analysis Of Load Capacity And Eddy Current Loss In Axial Permanent Magnet Coupling

The axial permanent-magnet coupling which uses the interaction of the rare earth permanent magnets to transfer mechanical energy without mechanical connection, is a new type of coupling. The axial permanent-magnet coupling is mainly consisted of three parts:the driving magnetic ring, driven magnetic ring and the isolative plate. The difference between the axial permanent magnet coupling and the general coupling is that it has no direct mechanical connection, but the mechanical movement and energy are transferred through the interaction of the driving magnetic ring and driven magnetic ring which are installed in the driving shaft and driven shaft, and it is a non-contact coupling. It has achieved transmission without mechanical connection and solved the protection of overload, pair, soft start, and also solved a series of seal leakage problems in the transmission of mechanical device. It is now used widely in the chemical machinery, instruments machinery, food, vacuum and so on.As the axial permanent magnet coupling in the course of the work is able to pass the motion and energy without mechanical contact, it virtually eliminating the leaks resulted from the shaft seal. The size of the axial force which is generated from the interaction between the driving magnetic ring and driven magnetic ring is related to the life issues of the bearings which are at both ends of the driving shaft and driven shaft; the transmission torque is the main parameters as a measure of coupling performance. In the course of the axial permanent magnet coupling, the isolative plate relative to the driving rotor and driven rotor has a certain speed, and the magnetic field between the driving and driven magnetic ring constantly changing, so in the metal isolative plate induced current is generated and that is vortex. Since the existence of the isolative plate of its own resistance, it will produce a lot of heat, resulting in significant loss of energy, reducing the mechanical transmission efficiency, how to accurately calculate the size and energy losses of eddy current, and take effective measures to improve the efficiency of magnetic drive has become the most concerned topic of the field of permanent magnet couplings. The research of permanent magnet couplings in foreign countries for a long time.The research of the principles and characteristics of permanent magnet coupling in domestic only started in eighties, includes the following three aspects:air-gap magnetic field, magnetic torque and eddy current losses within the isolation plate, and its approach is relatively simple. With the development, its research methods are constantly improved and perfected and species also increases. For the calculation of axial force and torque, there are a variety of methods domestic and international, including empirical methods, finite element method and magnetic circuit method and so on. Since the calculation of the equivalent magnetic charge method have higher precision and shorter time compared to several other algorithms, the time is short, so this article will adopt this method to calculate and analysis the axial force between the driving magnetic ring and driven magnetic ring, transmission torque and eddy current generated within the isolative plate, and then use finite element software ANSYS to analysis and verify the air-gap magnetic field and eddy current loss.In this paper, the axial force, torque, air gap magnetic field strength and the eddy current losses are analyzed and calculated of axial permanent-magnet coupling with twelve poles. The detailed contents shown as followed:(1) This part briefly introduces the background and significance of the axial magnet coupling permanent magnetic coupling, the development trend, and research contents of this article.(2) The study of force and torque of the axial permanent magnet coupling. The mathematical model of force and torque based on the equivalent magnetic theories of the axial permanent magnet coupling is established.(3) The analysis of air gap magnetic field of the axial permanent-magnet couplings. The mathematical model of Air-gap magnetic field based on the equivalent magnetic theories of the axial permanent magnet coupling is established, and influences of main parameters on air gap magnetic field are analyzed.(4) The analysis of eddy current loss of the axial permanent-magnet couplings. The mathematical model of eddy current loss is established, the formula of eddy current loss is derived and the size of the eddy current loss is calculated and influences of main parameters on eddy current loss are analyzed.(5) The finite element analysis of Air-gap magnetic field and eddy current losses. The finite element model of air-gap magnetic field and eddy current loss is established. Using the electromagnetic modules of ANSYS software, Air gap magnetic field of axial Permanent magnet coupling and eddy current loss of isolation plate are analyzed respectively. The theoretical results are compared with the finite element analysis and further verify the correctness of the results.(6) Finally, conclusion of this article and prospects of the study in the future are given.