The Study On The Control Of AC Servo Drives

AC servo drives have got more and more applications in the past decades. Since having played a dominant role in the field of drives, it should be paid more attention by the researchers on such area.Besides, from the academic view, ac servo drives embrace the many areas of technologies: materials, motor design, sensors, microelectronics, power electronics, computer control, etc. And it, is also the mainstream of servo drive. Obviously, The research of ac servo drives will give a momentum to the development of related technique areas.In this dissertation, to overcome the parameter variations of ac drive system, some new efforts are made. The goal of the study is to improve the robustness of ac drive system and to meet the increasing demand of high performance on ac drives.Firstly, in chapter 1, the generalizations about ac drive system are given, including the developing states and trends of ac drives, and the main contents of this dissertation.In chapter 2, a generalization of ac drive's control strategies is given. The contents include the control strategies based on the mathematical model of ac motor, the control strategies based on modern control theory and the control strategies based on intelligent control.In chapter 3, the hardware of ac servo drives is discussed, including the construction of ac servo drives, etc. and an AC 200 position servo system is introduced.In chapter 4, the problem to simplify the system's mathmatical model is analyzed and discussed based on vector control.In chapter 5, for alleviating the chattering of SMC (Sliding model control) ac servo drive system, a new method is proposed. This new method employ Fuzzy Logic (FL) in SMC. The new hybrid scheme makes full use of the advantages of SMC and FL. FL is used to reduce the chattering of the system while SMC enhances the robustness to parameter variations and load disturbance. Both simulation studies and experiment results indicate the superiority of proposed approach over the conventional SMC methodsIn the last chapter, chapter 6, the problem of motor efficiency is discussed. And proposed a new approach, Fibonacci Sequence based on-line efficiency optimization control, for improving the efficiency of induction motor drive system. The most attractive feature of this method is its independence from the loss model. Furthermore, it makes the system operate at maximum efficiency quickly. For compensating the decrease of flux, which results from the decrement of the excitation current and will result in torque loss, Feedforward algorithm is employed. The simulation results demonstrate the effectiveness of the proposed method.