Optimization Design And Electromagnetic Force Characteristics Of Bearingless Permanent Magnet Synchronous Motor

Compared with bearing-based motors,bearingless permanent magnet synchronous motors(BPMSM)have the advantages of no mechanical friction,long life and high efficiency,and have a wide range of application prospects in many hightech fields such as flywheel energy storage and high-speed centrifuges.Two sets of three-phase windings are embedded in the stator slot of BPMSM with double winding structure,which not only reduces the utilization rate of the slot,increases the loss on the stator side,but also increases the difficulty of motor processing and limits the development of BPMSM.Different from the traditional double-winding structure,a set of multi-phase winding is embedded on the stator side of the single-winding BPMSM to combine the suspension mechanism of bearingless motor with the theory of multi-phase motor to realize the drive and levitation of the rotor,which is of great research significance.In this dissertation,the suspension mechanism of double-winding BPMSM and the principle of multi-control degrees of freedom of multi-phase motors are first described,and then the conditions of single-winding BPMSM rotor drive and stable suspension are obtained.On this basis,the two-dimensional finite element model of the motor is established,the mathematical model of single-winding BPMSM is derived,and its suspension force model is established.Based on the finite element simulation results,the influence of stator winding current and eccentric magnetic tension generated by rotor eccentricity of single-winding BPMSM on the controllable suspension force is analyzed,and the accuracy of the suspension force model is verified.In view of the high requirements of single-winding BPMSM on torque performance and suspension force performance,this paper aims to improve the motor performance by optimizing the single-winding BPMSM magnetic pole,and a multiobjective optimization scheme based on improving the eccentric pole structure is proposed to reduce the torque ripple and levitation force pulsation of single-winding BPMSM under the premise of ensuring the output capacity of the motor.The singlewinding BPMSM before and after optimization is compared and analyzed,and the superiority of the optimized motor performance is verified.Aiming at the problem that single-winding BPMSM is affected by unbalanced electromagnetic force at all times,the spatiotemporal characteristics of radial electromagnetic force when the motor is normal and considering rotor eccentricity are studied,and the harmonic order and harmonic distribution law of radial electromagnetic force of single-winding BPMSM are calculated,and the correctness of this law is verified by finite elements.On this basis,the influence of unbalanced electromagnetic force generated under different eccentricity degrees of rotor on the electromagnetic vibration of the motor is studied.The research methods and conclusions of this paper provide a reference for the further development of singlewinding BPMSM.