Research On Bearingless Flux Switching Permanent Magnet Motor And Its Control System

As a kind of high performance stator-Permanent Magnet(stator-PM)motor,flux-switching PM motor(FSPMM)solve some problems such as mechanical integrity,thermal instability and demagnetization of PMs.At the same time,its PMs locate in the stator while the rotor is a simple salient structure.It is convenient for flux regulation of the air-gap flux distributions.By the effect of powerful assembled flux,the torque output capacity of FSPMM can be improved under the same size o f the motor.On the other hand,bearingless motor has the characteristics of wear-free,maintenance-free,lubrication-free and long operation life.There are broad application prospects in some special areas,such as ultra clean medical and health,high precision,sealed pump and so on.In this dissertation,a bearingless flux-switching permanent magnet motor(BFSPMM)is proposed,which combines bearingless motor technology with the basic theory of FSPMM.Around the aspects of structure design,operation principle,electromagnetic performance analysis,mathematical model,control and digital control system.The novel structure of BFSPMM is designed.The generation principle of radial suspension forces has been studied.The related performances between torque and radial suspension forces have been analyzed.The mathematical models of torque and radial suspension forces are established.The adaptive non-singular terminal sliding mode control is proposed.The digital control system of BFSPMM is designed and constructed.And the experimental research is carried out.The main work and achievements of this dissertation are as follows:(1)Due to the complex flux distribution,the coupling problems between torque and radial suspension forces,the difficulty of precise direction control of radial suspension forces,and the lower power per PMvolume performance,which are easy to occur.In order to solve these problems,a novel BFSPMM is proposed.On the basis of basic motor structure,some parameters and structure are determinded such as the power size equation of the motor,the ratio of stator to rotor poles,the structure of PMs,the basic structure parameters,winding structure and parameters are designed.Among them,the selection of PM structure is analyzed by finite element method,and the motor structure is finally determined by comparing the main electromagnetic performance differences between the two PM structures and the differences of power per PMvolume performance.Finally,the generation principles of torque and radial suspension forces are analyzed in detail.(2)The basic electromagnetic performances of BFSPMM,such as flux distribution,no-load PM flux linkage,no-load back EMF,cogging torque,inductance,torque and radial suspension forces,are studied analyzed by finite element method.Based on the analysis above,the rationality of the basic motor structure of BFSPMM is proved.At the same time,the correctness and validity of generation principle of torque and radial suspension forces are verified.(3)The direction of radial suspension forces of BFSPMM is difficult to control and the coupling problems between torque and radial suspension forces are serious.The controllability of radial suspension forces and the coupling problems between torque and radial suspension forces are deeply analyzed.Because of the special design of suspension force windings,the any magnitude and direction of radial suspension forces can be realized,and radial suspension forces can be controlled reliably.By finite element met hod,the coupling problems between torque and radial suspension forces are analyzed in detail,which proves that it possesses good decoupling performance.(4)For the mathematical model of torque subsystem of BFSPMM,voltage equation,flux equation and mechanical motion equation are established.The mathematical model of radial suspension forces is realized by combining Maxwell tensor method.The mathematical model of magentomotive force of torque windings,suspension force windings and PM are established as well as air-gap permeability model.Then,the mathematical model of radial suspension forces is deducted.Finally,the correctness and validity of mathematical model of radial suspension forces are proved by comparing the finite element calculation results with the mathematical model calculation results.(5)Based on the conventional stator field-oriented control,an adaptive non-singular terminal sliding mode control is proposed.This control possesses some advantages such as low dependence on mathematical model,stronger anti-jamming ability and faster dynamic reponse of the system and so on.This control method can improve the whole system by smaller overshoot and steady-state static error,stronger robustness,so the system can be converged in a predetermined time.The feasibility of this method is vertified by simulation results.(6)The processing of experimental prototype of BFSPMM is completed,and its digital control system which based on TMS320F28335 is designed and constructed.In order to verify the validity and correctness of the control system,SVPWM technology is used to realize stator field-oriented control.Then,the start-up,suspension of the rotor,speed regulation and interference experiments of BFSPMM are carried out.It can be seen fro m the experimental results that the digital control system of BFSPMM can realize the stable suspension operation.At the same time,this system possesses excellent dynamic and static characteristics.All of these advantages above provide an experimental basis for its application in some fields such as ultra clean medical and health care,sealed pump and other related fields.