Abstract
To handle the unbalanced vibration caused by uneven rotor mass distribution in a bearingless induction motor (BIM), a control strategy that integrates unbalanced feed-forward compensation and current compensation is presented. Firstly, based on the analysis of the BIM rotor vibration mechanism and the unbalanced vibration influence on the performance of the BIM, the dynamic model of the rotor is derived. Secondly, an unbalanced force feed-forward compensation controller is designed to extract the synchronous vibration signals through the synchronous signal detection unit, and then the compensation force components are generated by unbalanced feed-forward compensation controller. In addition, considering the influence of current in the rotor induced by suspension winding, a current compensation link is applied to the system to enhance the suspension performance. Finally, a rotor unbalanced vibration compensation control system of the BIM is established. The simulation and experimental results show that the proposed compensation control strategy not only can effectively reduce the rotor radial displacement and suppress the unbalanced vibration, but also can improve the suspension performance.
Highlights
A bearingless motor is a new type of motor which breaks through the balance of air-gap magnetic field of the traditional motor to produce electromagnetic torque and radial suspension force
In this paper, based on the analysis of unbalanced vibration caused by the rotor eccentricity of the bearingless induction motor (BIM), the dynamic model of the rotor vibration is derived
The rotor vibration is reduced by means of the control strategy combined with the unbalanced force feed-forward compensation and current compensation, and the effectiveness of the proposed method for vibration suppression is verified by comparing the rotor displacements with and without compensation in simulation and experiment
Summary
A bearingless motor is a new type of motor which breaks through the balance of air-gap magnetic field of the traditional motor to produce electromagnetic torque and radial suspension force. As the control system is adjusted by traditional PID control, it is difficult to meet the high-performance control requirements of the BIM nonlinear system, which needs further improvement in future research [36], [37] In this strategy, the feed-forward compensation controller is applied to the suspension control system, the synchronous signal processor is utilized to extract the synchronous component of the displacement signal and the synchronous component is converted to weaken the unbalanced exciting force. The simulation and experimental results show that the proposed vibration suppression strategy can achieve good suspension effects, which realizes the stable suspension in a wide speed range, and reduces the radial offset caused by the rotor vibration of the BIM. 1d and 1q are the air gap flux linkage components of the torque winding in the d-q coordinate system; is2d and is2q are the stator current components of the suspension winding in the d-q coordinate system; N1 and N2 are the effective turns of the torque winding and suspension winding; P1 and P2 are the pole-pairs of the torque winding and the suspension winding; r is the outer diameter of the rotor; L2m is the mutual inductance of the suspension winding; μ0 is the vacuum permeability; l is the effective length of the shaft
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