Mathematical model and control technology of bearingless PMSM

A bearingless permanent magnet-type synchronous motor (PMSM) is a strong-coupled complicated nonlinear system, establishing exact mathematical models of electromagnetic torque and radial suspension forces is a precondition for designing control system of the bearingless PMSM. The inductance matrix of the bearingless PMSM is given after analyzing the magnetic flux linkage intersection between torque windings and radial suspension force windings. Based on the operating principle of the bearingless PMSM and this inductance matrix, complete formula of radial suspension force and electromagnetic torque equation of the bearingless PMSM are deduced. In order to realize decoupling control of the bearingless PMSM, control strategy of rotor flux orientation is adopted in the paper, and on this basis, the diagram of control system and digital control test rig are designed. The experimental results testify the validity of the adopted method.