| With the advantages of high power density,small torque ripple,and high reliability,dual threephase permanent magnet synchronous motors have been used as a key executive component in servo control systems,the research of high-performance control strategy has become a hot spot.Based on the analysis of the electromagnetic characteristics,structural characteristics,and mathematical models of dual three-phase motors,this thesis studies the frequency characteristics of typical servo control systems.The corresponding improved methods are proposed in the typical position servo systems to solve the problems of poor current response,slow response speed,and low tracking accuracy.Moreover,back-EMF compensation is added to the current loop which can improve the current response.A limiter in the integral part of the speed controller is added to achieve anti-integral.To achieve error-free tracking,a feedforward and feedback compound controller are designed through the analysis of the steady-state error of the servo control system.The main research contents are as follows:1.The electromagnetic and torque characteristics of the dual three-phase motor are briefly analyzed.The dual d-q transformation model and the vector space decomposition model of the dual three-phase motor are established.The basic principle of SVPWM of the six-phase inverter is explained,Then,the vector control block diagram of the dual three-phase motor is built,which lays the foundation for the subsequent servo research.2.By analyzing the transfer function of each object in the position servo control system,a frequency domain model is constructed.The amplitude-frequency and phase-frequency characteristics of the current loop,speed loop,and position loop are analyzed.Each closed loop is corrected into a typical system by designing a controller to meet the performance requirements.3.In order to solve the problem of current response fluctuation caused by back-EMF,the product of torque coefficient and speed given value is used as compensation to improve the effectiveness of the current response.In the integral part of the speed controller,the limiter is added to make the system desaturate quickly and speed up the response of the system.The feedforward feedback compound controller of the position loop is designed by analyzing the steady-state error of the position.The controller improves the position tracking accuracy and can realize error-free tracking for various input signals.Meanwhile,the simulation model of the position servo control system is built to verify the control principle.4.The hardware and software systems of servo control are designed,and the key circuit and software are analyzed.A method for measuring the mechanical angle of the rotor with a multi-pair resolver is proposed.Then,the experimental platform of the dual three-phase motor position servo system is built.Finally,the experimental results verify the effectiveness of the proposed control method. |
