A new permanent magnet biased radial magnetic bearing

A new permanent magnet biased radial magnetic bearing is proposed. The control flux passes through the second air gap. The magnetic bearing has four stator pole pieces compared to the heteropolar bearing which has eight stator pole pieces, so the new magnetic bearing can reduce the eddy loss three times. The radial magnetic bearing is analyzed and calculated by using equivalent magnetic circuit and 3D finite element method (FEM). The math expression and some equations are given for maximum carrying capacity, current stiffness and displacement stiffness. Some parameters design and calculation method are presented. The theory analysis and simulation show that this radial magnetic bearing is of little displacement stiffness produced by permanent magnet by means of designing the second air gap. It is useful to reduce perturbance, the stiction torque and improve control accuracy of reaction flywheels. It has wide application in bearingless motor, other flywheel systems, and so on.