Design of four-axis magnetic bearing for high speed motor

Active magnetic bearings can not only solve the bearing wear and life problems but also reduce the loss and noise of bearings, which makes it more and more popular in the use of high speed motor. In this paper, the design procedure and control method are presented for four-axis magnetic bearings designed for a 200kW/40000rpm high speed motor. The working principle and actuator model of magnetic bearings are introduced and graphically illustrated at first. Both analytical method and finite element analysis (FEA) method are used to design the actuator of the magnetic bearings and their results are compared to validate the results. Then the layout of the high speed motor integrated with the designed active magnetic bearings is introduced. To improve the dynamics performance of the high speed motor system, the rotor dynamic of high-speed rotor are also analyzed in detail. In the end, a novel converter for the magnetic bearing drive is introduced. Moreover, an effective control method is simulated in detail and the simulation results show the feasibility of the control method.