Optimal Design And Vibration Suppression Of Outer Rotor Coreless Bearingless Permanent Magnet Synchronous Motor

As an important equipment in modern industrial production,the motor plays an important role in social production.The traditional motor uses mechanical bearings to support the rotor,which hinders the development of the motor towards the direction of high speed,high precision,high efficiency and maintenance free.Bearingless permanent magnet synchronous motor(BPMSM)gets rid of the limitation of mechanical bearing,and can realize the stable suspension of rotor while operating.It has a broad application prospect in aerospace,life science,flywheel energy storage and other fields.In order to reduce the core loss,improve the energy transmission efficiency and reduce the torque ripple caused by cogging torque,a new type of outer rotor coreless BPMSM(ORC-BPMSM)is proposed in this dissertation.The ORC-BPMSM integrates the advantages of bearingless permanent magnet motor,such as no friction and wear,long service life,maintenance free,and the advantages of coreless permanent magnet motor,such as no cogging torque,low loss and so on.The ORC-BPMSM is taken as the main body,the working principle,mathematical model,parameter optimization design,rotor vibration compensation control method and digital control system of which are studied.The main work and achievements of this dissertation are as follows:(1)The research background of bearingless motors and coreless motors are introduced,and their development process are summarized with time node.Then,the research status and future development trend of ORC-BPMSM are summarized.(2)The basic structure of ORC-BPMSM is introduced,and the working principle of ORC-BPMSM is analyzed.The principles of electromagnetic torque and suspension force of ORC-BPMSM are expounded.Considering the rotor eccentricity,the mathematical models of electromagnetic torque and radial suspension force are established.Then,the rotor dynamic equations are derived based on the mathematical model.(3)The initial parameters of ORC-BPMSM are designed,and the corresponding finite element model is established.In order to improve the performances of the motor output torque and suspension force,Taguchi-Response Surface Method(T-RSM)is used to optimize the average and ripple values of the output torque,and that of the suspension force.The optimization variables are the pole-arc coefficient,the thickness of permanent magnet,the length of air gap and the thickness of the rotor.Then,in order to verify the feasibility of the optimization,the simulation waveforms of the torque and the suspension force before and after the optimization are compared and analyzed by finite element simulation software,and the conclusion is obtained that the output torque and the suspension force performance of the motor are improved after the optimization.(4)In order to solve the vibration problem caused by rotor mass unbalance,a variable step size Least-Mean-Square(LMS)adaptive filter is proposed.Based on the traditional fixed step size LMS filter,the step size is designed as a Sigmoid function related to the error.The improved LMS algorithm has better convergence performance and accuracy,which can better suppress the vibration signal.Then,the designed filter is simulated in the MATLAB/Simulink simulation environment,and the effectiveness of the proposed unbalance compensation control strategy is verified.(5)The digital system control platform of ORC-BPMSM is designed,including hardware design and software design.The hardware design includes the design of DSP minimum system board,power driver board and interface circuit board.The software design includes the design of main program and interrupt service subroutine.The relevant experiments are completed on the experimental platform to verify the reliability of the motor.