Research On Fault-tolerant Control Of Six-phase Bearingless Slice Motor

The bearingless slice motor not only has the advantages that the ordinary bearingless PM motors have, such as without lubrication, no mechanical noise, long life and high integration, but also has some characters like simple structure, high axial-utilization, small volume, low cost and high reliability. So it has unique application advantages in high speed driving and the ultra-pure fields including medical industry, modern semiconductor manufacture, biology, and aerospace industry.This paper takes the six-phase bearingless slice motor as the research object, researching the fault-tolerant control of the motor with faulty phases. The mainly work can be concluded as follow: Firstly, the structure and the working principle of the six-phase bearingless slice motor were introduced. The short-circuit current of the faulty phase was derived, and the relationship between the short-circuit current and each parameter of the motor was researched. Then, the influence of the levitation force and torque caused by the short-circuit current was analyzed.Secondly, a short-circuit fault-tolerance control strategy was presented by the stator-current reconfiguration principle. In the strategy, levitation force compensation and torque compensation were added to the normal phases'current based on the mathematical model of the levitation force and torque. A general stator-current mathematical model when each phase worked at the short-circuit fault state was put forward. Then the open-circuit and the short-circuit fault-tolerance control strategies were combined, an improved fault-tolerant control strategy suitable for ordinary fault modes were presented. All the fault modes can be carried out in the fault-tolerant control were concluded.Finally, the finite element simulation model of the motor was established. The open-circuit and short-circuit fault self-diagnosis methods based on the characteristics of the faulty phases'current were proposed, which can judge the real time state of the motor. Then the software control system of the experimental platform was designed, including the calculation programs, the faults self-diagnosis programs, and the two fault-tolerant control programs.