Control Systems and Dynamics of Cone-Shaped Magnetic Bearings Actuated by Five Electromagnets

A five-axis control system actuating five electromagnets is considered for a symmetric magnetic bearing system composed of six electromagnets whose pole faces are in the shape of a cone to combine radial bearings with a thrust bearing. The extra one electromagnet is used only as a bias actuator. The square-root compensation is applied to linearize the control force. The linearized model is obtained with the five resultant inputs which are given by the combination of actual inputs of the electromagnets. The control system is realized with the actual inputs asigned to generate these resultant inputs, the control inputs into the individual control axes. A little modification of the assignment of the actual inputs leads to a simpler form that gives some interaction. Experimental data are obtained for frequency responses of the control systems and transient responses to impact to show the characteristics of the system.