Fundamental Research On Vibration Analysis And Control For A Bearingless Switched Reluctance Motor

Taking the advantage of the similarity of magnetic bearings and motor structure, Bearingless Switched Reluctance Motor (BSRM) concentrates the magnetic suspension winding used to provide radial suspension force in the traditional Switched Reluctance Motor's (SRM's) stator, which is capable of rotating and magnetic suspension supporting functions. BSRM not only expands the theory and application scope of bearingless motor, inherits and exerts the high-speed feature of Switched Reluctance Motor (SRM) and its adaptability to harsh environment, but also, by initially controlling the radial position of the rotor, provides a new approach to solve the vibration and noise problems caused by asymmetric magnetic pull.This paper takes the 12/8 structure dual-winding BSRM as the object of study, and researches the magnetic vibration from the aspect of stator/rotor geometric eccentricity, rotor mass eccentricity and the controlling mode.From the in-depth study upon the previous research results, the mathematical model of BSRM is improved in this paper. The new model not only considers the magnetic saturation and the rotor eccentricity displacement of the motor during the running process, which has provided a more trusty basis to analysis motor's running state and to design the motor; but also solves the problem that previous models cannot be used to calculate the radial magnetic pull upon a single stator pole, whichhas laid the foundation for the prediction and control of vibration and noises in the BSRM. Secondly, as the unilateral magnetic pull is caused by the problem of stator eccentricity, the serious problem of vibration and noise becomes even worse. Based on theory of circumferential vibration and the characteristics of radial force in BSRM, by the system simulation based on Matlab/Simulink, this paper analyzed the compensation function upon the unbalanced radial force after introducing the bearingless technology into SRM, and points out that BSRM is more applicable in the field with low noise requirement.Then, as the rotation and suspension of BSRM is the result of motor main winding current and suspension winding current working together, the different combination of main winding and suspension winding will have direct impact upon the stator radial force and stator vibration. This paper makes an in-depth analysis from this aspect upon the several existing control strategies of the BSRMs. This paper calculates out the main winding and suspension winding currents when motor is ideal suspension with the several control strategies under different torque and radial load; it makes the analysis of time domain and frequency domain upon the generated radial force; it points out the control strategy for reducing the stator vibration, and lays the foundation for the choice of control strategies of BSRM under different situations. Experiments in this paper also verifies the theoretic analysis.Later, for the problem of rotor mass eccentricity caused by mechanical imbalance, in this paper, the adaptable filter based on Least-Mean-Square (LMS) algorithm is adopted to compensate the imbalanced radial force. It introduces the generation and features of imbalanced vibration, introduces in detail the theory and design of adaptable filter, analyzes the stability after introducing this filter, and makes the simulation and experiment verification of this plan.Finally, for the problem of rotor magnetic eccentricity existing in the actual running of rotor, this paper researches the impact of rotor eccentricity upon airgap magnetic field and stator vibration when the main winding is under different connections. It proposes the combination of main winding that can reduce the vibration and noises of bearingless reluctance motor.