Decoupling Structure for Heteropolar Permanent Magnet Biased Radial Magnetic Bearing with Subsidiary Air-Gap

For existing heteropolar permanent magnet (PM) biased radial magnetic bearing, magnetic circuits in X and Y channels are coupled with each other, which makes it more difficult to design the control system and influence control precision of the whole system. A new heteropolar PM biased radial magnetic bearing is proposed in this paper. The X and Y magnetic circuits of the presented bearing are independent of each other, which decreases the magnetic field coupling of the two channels significantly. First, the structure and working principle of the proposed bearing are demonstrated. Then, the analytical formulas for calculating the magnetic force of this magnetic bearing are deduced using the equivalent magnetic circuit method and virtual displacement principle. Finally, magnetic field distribution, basic magnetic force characteristics, and coupling characteristics of the designed magnetic bearing are analyzed by the 2-D finite-element method.