Research On Eight Magnetic Poles Heteropolar Radial-Axial Permanent Magnet Biased Magnetic Bearing

Permanent magnet biased magnetic bearings compared with active magnetic bearings have the advantages of reducing the system power loss, saving material, reducing the volume and weight with great application prospect. The novel eight magnetic poles heteropolar radial-axil permanent magnet biased magnetic bearing was proposed in this paper and the noval magnetic bearings were studied. First of all, the structure and working principle of the eight magnetic poles heteropolar radial-axil permanent magnet biased magnetic bearing were introduced, then the mathematical model was built based on equivalent magnetic circuit, and the performance of permanent and permanent magnet biased magnetic bearing were analyzed. Then taking the maximum bearing capacity into consideration, the parameters of the permanent magnet biased magnetic bearings were designed, and magnetic levitation force coupling for different degrees of freedom was also analyzed based on the bearing capacity formula. The results show that the magnetic levitation force coupling between the various degrees of freedom were low near the equilibrium position. Secondly, for the designed structure, three-dimensional finite element simulation of magnetic field were completed by Ansoft. The magnetic field distribution and the magnetic induction intensity near the air gap were analyzed, and the parameters were adjusted according to the simulation results. Through the simulation analysis of magnetic levitation force, the force-current curve and force-displacement curve were obtained. The magnetic coupling of the structure were simulated in order to verify the correctness of the coupling theoretical analysis. Finally, a series of experiments of the novel permanent magnet biased magnetic bearing designed and manufactured were conducted, including static suspension test, dynamic rotation test, dynamic response test and the magnetic bearing capacity test. The experimental results show that the eight magnetic poles heteropolar radial-axil permanent magnet biased magnetic bearing can be raised-up during 60 ms. The vibration amplitude of rotor was about 0.02 mm during static suspension test. After impact it took about 40 ms to be stable suspension. Better suspension performance could be satisfied even at the speed 3000 r/min with rotor vibration amplitude at about 0.06 mm. The maximum bearing capacity of actual radial and axial were 190 N and 170 N respectively. It takes up the 82.6% and 81% of corresponding bearing capacity.