Modeling, Design and Suspension Force Analysis of a Novel AC Six-Pole Heteropolar Hybrid Magnetic Bearing

To improve the radial suspension force of heteropolar hybrid magnetic bearing (HMB), a novel AC six-pole heteropolar HMB is proposed. Firstly, the structure, magnetic circuit, and suspension force generation principle are introduced and analyzed. Secondly, the equivalent magnetic circuits are established. The mathematical models of magnetic resistances, air gap magnetic fluxes, and levitation force are derived by node magnetomotive force (MMF) method. The main parameters of prototype heteropolar HMB, such as outer and inner air-gap length, winding turns, and permanent magnets, are designed. Then, the analysis model is established by MagNet 3D. The magnetic circuit, air-gap flux density, suspension mechanism, force-current relationships, force-displacement relationships, and force coupling characteristics are analyzed and calculated. Finally, the experimental system was built to test the levitation force and levitation displacement waveforms. The research results have shown that the proposed novel six-pole heteropolar HMB has a reasonable structure and magnetic circuit. The design method is also proven to be correct. Furthermore, it is compared with the traditional heteropolar six-pole HMB, the maximum suspension forces in the X and Y directions are increased by 1.96 and 2.02 times, respectively.