| In the field of advanced manufacturing,the requirement of motor performance is getting higher and higher,so the development of high-quality transmission system has become an urgent problem to be solved.For the advantages such as high torque density,low torque ripple and strong fault-tolerant performance,multi-phase motor has a broad application prospect in the fields of aerospace,medical and health,urban rail transit and so on.At the same time,the bearingless motor,relying on its superiority of no friction and wear,no lubrication and maintenance free,has attracted extensive attention in the fields of ultra clean medical treatment,high pressure seal pump,high speed and high precision,etc.The multi-phase bearingless motor combines the dual advantages of multi-phase motor and bearingless motor,which can not only realize the rotating operation without the support of bearing,but also have many advantages of the multi-phase motor.In this dissertation,a five-phase 10-slot/8-pole fractional-slot concentrated dual winding bearingless permanent magnet synchronous motor(FSCDW BPMSM)is taken as the research object,and the winding structure,electromagnetic analysis,operation mechanism,control method and digital system are studied.The winding structure of the five-phase FSCDW BPMSM is designed,the shape of the permanent magnets(PMs)is optimized and the experimental prototype is developed.The generation principle and the interaction relationship of various radial suspension forces are studied.The mathematical model of the suspension subsystem and the torque subsystem is established,and the direct suspension force control based on the model reference adaptive is proposed.The five-phase FSCDW BPMSM digital control system is designed,and related research experiments are carried out.The main works and achievements of this dissertation can be summarized as follows:(1)The winding structure of five-phase FSCDW BPMSM is designed,the distribution of air-gap MMF is studied and summarized,the shape of PMs is optimized and the experimental prototype is developed.On the basis of comparing the traditional multi-phase fractional-slot and integral-slot concentrated winding motor,the multi-phase bearingless motor with fractional-slot and dual winding structure is proposed.An improved winding function method is proposed to study the distribution of the stator MMF,which is verified by finite element method.Combining the characteristics of the traditional five-phase motor using the third harmonic current to increase the torque density,the PMs are optimized as saddle-shaped to obtain the maximum output torque,and the optimal ratio of the third harmonic is sought.The performance of the torque and controllable radial suspension force of the motors with square-,saddle-,and sine-shaped PMs is simulated and compared.At last,a five-phase FSCDW BPMSM prototype is designed according to the optimized parameters.(2)The generation principle and interaction relationships of various radial suspension forces of five-phase FSCDW BPMSM are expounded.Since the five-phase FSCDW BPMSM with third harmonic current injected has more harmonic content in the air-gap MMF,the interaction relationships between harmonics are complicated.Thus,the magnetic equivalent virtual current analysis method is proposed,the influence of various radial suspension forces on the main suspension force is analyzed carefully by the method.It is verified that the five-phase FSCDW BPMSM with the saddle-shaped PMs can reconcile the contradiction between the motors with square-shaped and sine-shaped PMs,which can also greatly reduce the pulsation of the radial suspension force while improving its amplitude.(3)The mathematical models of five-phase FSCDW BPMSM torque subsystem and suspension subsystem are constructed.The voltage and flux linkage equations of the torque subsystem are established in the natural coordinates.Considering the effect of the third harmonic current on the torque of the five-phase motor,the equations of voltage,flux linkage,torque and motion are established in the synchronous reference frame by using the generalized coordinate transformation matrix.Based on Maxwell tensor method,the mathematical model of radial suspension force in eccentric rotor is derived,including controllable radial suspension force and uncontrollable radial suspension force.The mathematical model of controllable radial suspension force and the motion equation of suspension subsystem are established in synchronous rotating coordinate system.(4)A direct suspension force control method of five-phase FSCDW BPMSM is proposed based on model reference adaptive control method,and related simulation research is carried out.Aiming at the shortcomings of traditional vector control method such as weak robust performance and poor adaptive ability,a double-closed loop direct suspension force control strategy is adopted in the suspension subsystem.The voltage-current model is used to calculate the flux linkage produced by the winding current.To improve the accuracy of the calculation results,the model reference adaptive method is used to identify the stator resistance values of the two sets of winding.The simulation results verify that the direct suspension force control after the resistance on-line identification is more accurate and the suspension performance is more stable.The traditional control method of five-phase permanent magnet synchronous motor control method is adopted in torque subsystem,and the fundamental current and third harmonic current are simultaneously controlled by SVPWM space vector control.(5)A digital control system of the motor based on TMS320F28335 is developed,and relevant experimental research is carried out.The realization methods and techniques of signal detection and conditioning modules,DSP main circuit control modules and power drive modules are analyzed and studied,and the main hardware and software of the digital control system are designed.The experiments of startup,speed regulation and interference of the five-phase FSCDW BPMSM are studied.The experimental results show that the five-phase FSCDW BPMSM digital control system can realize the stable suspension and operation of the motor,and the system has good dynamic and static characteristics. |
PDF Full Text Request