Abstract: Due to the nonlinear relationship between force and current/displacement, the performance of active magnetic bearings (AMB) system based on local linearization varies greatly as the operating point of the spindle changes. The same stiffness and the same displacement tracking performance are demanded for grinding spindle with AMB especially when noncircular workpieces need grinding. The influence of changing operating point on performance is presented theoretically and proved with experiments. Linear compensation is adopted to realize global linearization because of its simplify. Three linear compensation methods: minimum flux (MIF), constant flux sum (CFS), constant flux product (CFP) are compared in terms of power loss and dynamic performance. The result shows that the power loss of MIF is least and CFS behaves best dynamic performance. The performance of AMB system based on global linearization is measured and almost the same result is obtained despite the change of operating point.

Key words: Magnetic bearings(MB), Nonlinear Linearization, Spindle