Coordinated Control Of Multi-motor Drive Systems And Its Applications To Straight Wire-drawing Machine

Cooperative control of multi-motor drive system has always been one of the important topics in the field of motion control. It is widely applied in automatic control of wire-drawing, textiles, printing and dyeing, paper making, steel rolling and other manufacture and production process. Research and Develop the multi-motor drive cooperative control system with high performance has a widely applicable prospect and practical significance.With the enhancement of the demands of manufacture technology, the system now available has not been able to meet the needs of modern manufacturing. In order to solve the problem of cooperative control with multi-motor drive system, the structure of the system requires to be further researched and the transmission performance of the motor should be improved. The thesis aims at solving the above problems. The research results have been applied to straight wire-drawing machine which has been a great benefit to society and economy. The main content of the paper is as follows:We first study the structure and characteristics of the asynchronous motor control system, and the type and characteristics of non-cross-coupled multi-motor drive system as well. Considering the uses of AC motor drives in multi-motor drive system and the large differences of the axle load disturbance, a new cross-coupled multi-motor drive system structure is proposed which can achieve good dynamic and static performance.To obtain good performance of induction motor vector control system without speed sensor, from the SVPWM principle, the thesis studies the discriminant of the current polarity and the dead zone compensation method. According to the angle of voltage vector in the static coordinates and the angle of electrical power factor, the current vector in the static coordinates can be calculated. Thereby the phase current polarity can be obtained, and a dead-zone compensation method has been proposed. Based on vector control system of asynchronous motor, we design an adaptive sliding mode speed observer which has two sliding current observers. Through the interaction of two observers, the dependence on the accuracy of the electrical parameters can be reduced.On the basis of simplifying the dynamic structure of the vector control system, the transfer function of speed ring in vector control system is obtained, which facilitates the coordinated controller design. The thesis adopts PI controller and presents an efficient non-convex optimization based method for designing PI controllers. The design is based on optimization of load disturbance rejection with constraints on sensitivity and overshoot of set point response. Thus, the formulation of the controller design captures three essential aspects of industrial control problems, leading to a non-convex optimization problem. So as to further enhance the properties of the coordinated control of multi-motor drive system, such as robustness, rapidness, degree of coordination, tracking accuracy and so on.According to the components and functions of the vector control system, a control system based on DSP hardware and software is designed; according to the components and functions of the multi-motor coordinated control system, a control system based on AVR hardware and software is designed. Based on the realization of both hardware and software of Vector Control System and cooperative control system, the experimental multi-motor drive coordinated control system is constructed which involves three parts as start-up characteristics experiment, dynamic tracking experiment and regulation experiment, and the validity of the proposed control mode is proved.According to the techniques and applications of the straight wire-drawing machines' coordination control system driven by multiple asynchronous motor, the thesis proposes a method which can arbitrarily cut blocks. By further studying the design technology of the multi-motor drive coordinated control system, a control strategy based on PI regulation for the multi-motor drive coordinated control system is designed. Furthermore, an asynchronous iterative method based on controller output is investigated to identify the speed ratio coefficient, so as to achieve a fast dynamical tracking performance. In addition, illustrations are presented to explain the accomplishment of the constant tension control of winder and the repetitive control of the strand oscillator servo system. The simulation and experiment results and the performance testing results with straight wire-drawing machine control system show the correctness and effectiveness of the system structure and control strategy.Finally a brief review is given. Some future research prospects are highlights.