Fuzzy Adaptive Dynamic Surface Control Of AC Motors

In recent years, Alternating-Current motors gradually replace DC motors in the industrial application because of their simple structure, low cost, high reliability and ruggedness. It is still a challenging problem to improve the efficiency of its operation of AC motor because its dynamic model is usually multivariable, coupled and highly nonlinear. Therefore, research of advanced control strategy, which improves the dynamic and static performance of ac motor drive system, is a rich theoretical and practical application value of the research subject.In order to solve the problems of the classical control method of AC motors, the problems of position tracking control for PMSM and induction motor including iron losses systems by incorporating the dynamic surface technology into adaptive backstepping. During the design process, fuzzy logic systems are used to approximate the unknown nonlinear functions in the systems, and combine dynamic surface technology with backstepping to design nonlinear controller. The proposed method can eliminate the influence of unknown parameters, overcome the problem of “explosion of complexity” inherent in the traditional backstepping and guarantee the high quality of the system.First, the adaptive fuzzy dynamic surface control is proposed for a class of single input single output strict feedback nonlinear systems. During the design process, fuzzy logic systems are used to approximate the unknown nonlinear functions in the systems, and the dynamic surface control technique is used to overcome the problem of “explosion of complexity” inherent in the traditional backstepping design procedure by introducing first-order low-pass filters, then backstepping is employed to design adaptive fuzzy controllers. Finally, Lyapunov method is used to analyze the stability of the system. The controller can ensure the boundedness of system and the good tracking performance.Second, the problem of position tracking control for Permanent magnet synchronous motor is proposed based on dynamic surface technique and fuzzy appromaximation via adaptive backstepping. Fuzzy logic systems are used to approximate the unknown nonlinear functions in the PMSM systems and the dynamic surface control technique is used to overcome the problem of “explosion of complexity” inherent in the traditional backstepping design procedure by introducing first-order low-pass filters. Then backstepping is employed to design controllers. Finally, Lyapunov method is used to analyze the stability of the system. The designed controller can guarantee system tracks the given signal quickly and all the closed-loop signals are bounded. The simulation results are provided to demonstrate the effectiveness and robustness against the parameter uncertainties and load disturbances.Third, for the dynamic model of induction motors including iron losses, the dynamic surface backstepping technology is used to design the new fuzzy adaptive position controller. Fuzzy logic systems are used to approximate the unknown nonlinear functions in the induction motor systems and the dynamic surface control technique is used to overcome the problem of “explosion of complexity” inherent in the traditional backstepping design procedure by introducing first-order low-pass filters. Then the adaptive technology is combined to estimate the unknown parameters. Furthermore, backstepping is employed to design controllers. It should be pointed that the proposed controller has a simple structure and only one adaptive parameter. So it will be easy to be implemented in practice. And also the controllers can guarantee that the boundedness of all the signals in the closed-loop system. The simulation results are provided to demonstrate the effectiveness and robustness against the parameter uncertainties and load disturbances.