Air-gap flux oriented vector control for the sensorless bearingless permanent magnetic motor

A bearingless permanent magnetic synchronous motor (BPMSM) has combined the characteristics of a permanent magnetic synchronous motor and magnetic bearings. The rotor suspension force is closely related to the air gap magnetic field of the torque windings. So accurately getting the magnitude and phase of the air-gap magnetic field on the torque windings is the key to precisely control the levitation force. And to achieve the stable suspension of the BPMSM, it requires accurate real-time detection of the rotor radial displacement. In the application of the BPMSM, the rotor field orientation control method is usually used, but it cann´t achieve a complete decoupling control. In response to what is mentioned above, a new control algorithm for the surface mount-type BPMSM based on the torque winding air-gap-flux-oriented vector control and a detection method using suspension winding air-gap flux to calculate the rotor radial displacement under rotating coordinate system have been proposed in this paper. For the further optimizing control, based on the feed forward control theory, it has introduced the suspension force feed forward compensation in the suspension control subsystem to eliminate the delay between the levitation force and its command. Finally, the Matlab / Simulink tool has been used to establish the simulation model. The simulation results show that the proposed algorithm can achieve the fully decoupling between electromagnetic torque and suspension force, realizing the stable operation without the radial displacement sensor, with the good dynamic and static performance and hardly any delay.