The Research Of Sliding Mode Control In Servo Drive System

With the development of modern industrialization, high performance AC servo drive system is widely used in various areas. AC servo drive system is a high order, nonlinear, coupling system, in order to realize better characteristic of the system, the higher performance control strategy is expected. In the dissertation, some new efforts are made to overcome the parameter variations of AC servo drive system. The purpose of the study is to improve the robustness of AC servo drive system and to meet the increasing demand of high performance on AC servo drive system.Sliding Mode Control (SMC) has been known for its robustness in accounting for modeling imprecision and bounded disturbances. However, in practice, the high frequency chattering phenomenon becomes a severe problem when it comes to SMC. Fuzzy Logic Control (FLC) has excelled in dealing with system which is complex, non-linear, or time-varying as it convert the linguistic control strategy of human experience or experts' knowledge into an automatic control strategy. At the same time, the major drawback of FLC is the lack of design techniques. Merging of the FLC with SMC can form a Fuzzy Sliding Mode Controller (FSMC). In this hybrid control system, the advantage of the SMC lies in its ability to account for modeling imprecision and external disturbances while the FLC can reduced chattering and provides better damping.The dissertation studies an AC servo drive system with the Permanent Magnet Synchronous Motor (PMSM) as the executive component, focus on the design and development of fuzzy sliding mode vector control system. First, by analyzing the mathematical models of the PMSM and the vector control strategy, the disadvantages of the conventional methods is found. Then, an sliding mode control is proposed which is a more ideal methods compared with the conventional. At last, an fuzzy sliding mode control is proposed. The fuzzy inference mechanism is utilized to estimate the bound of uncertainty, so it not only can fully exert the characteristics of SMC which are insensitive to parameters change and disturbance, but also has the ability of fuzzy self-adjusting, thereby the aim of decreasing chattering can be achieved. To prove practicability of intelligent ccontrol in AC servo drive system ,the dissertation uses the software of MATLB/Simulink to make a simulation. The simulation results show that the theory proposed consists with the results of simulation.The system meets the demand of required performance and paves the way for future research.