Design And Control Method Research On Conical Bearingless Permanent Magnet Synchronous Motor

Bearingless Permanent Magnet Synchronous Motor(BPMSM)has the advantages of no friction and wear,no lubrication,long life,high efficiency and high power factor.Applicable to flywheel energy storage,aerospace,medical instruments,chemical industry,precision machining and other fields.Conical Bearingless Permanent Magnet Synchronous Motor(CBPMSM)can not only realize high-speed rotation and radial suspension,but also has the ability of axial suspension.Therefore,the five-degree-offreedom maglev system based on two CBPMSM structures can reduce the axial length and improve the system integration,but also poses a challenge to the motor rotation and suspension control.At the same time,the mathematical model of the system is more complex,and each component has strong coupling,which increases the complexity of the control algorithm.In this dissertation,the conical bearingless permanent magnet synchronous motor is taken as the research object,and the operation principle,mathematical model and control strategy are studied.Firstly,the body structure of conical bearingless permanent magnet synchronous motor is introduced in detail,and the principle of rotor suspension force is analyzed.The mathematical model of suspension force of CBPMSM is established based on Maxwell stress tensor method and electrical theory.According to the design objectives,the basic size of the motor is preliminatively designed and simulated by Ansoft Maxwell finite element software.The relevant electromagnetic characteristics and characteristics are studied,and the mathematical model of suspension force is compared with the simulation results to verify the correctness of the model.Secondly,in order to realize the five-degree-of-freedom suspension of the motor,a simple decoupling design of the mathematical model is carried out,and a magnetic field oriented control method is proposed for the system to realize the double closedloop high-precision control of the CBPMSM torque system and suspension system.The control structure block diagram of the system is given.Finally,the hardware circuit and software of the conical bearingless permanent magnet synchronous motor control system are designed in detail,and the function of each module is described.The minimum system board,power driver board and interface circuit of DSP are designed and the software flow chart is provided.After the completion of the experimental platform,the experimental analysis of CBPMSM is carried out,mainly to study the suspension characteristics of CBPMSM in static state and dynamic state.The experimental prototype is verified to achieve stable suspension.