Ac Motor Adaptive Control Based On Fuzzy Approximation

Modern electrical drives based on AC (Alternating-Current) motors are the most spread automatic electromechanical systems. AC motors including the induction motor and the permanent magnet synchronous motor are multivariable, high-order and tight coupling nonlinear system. It is a challenging research subject full of theoretical significance and application value to get their high dynamic and static performance. The adaptive fuzzy method based on backstepping technology is an effective method to deal with the nonlinearity. Fuzzy logic systems are used to approximate the nonlinearities in order to overcome the system uncertainties of modeling and parameters. The adaptive technology is used to estimate the unknown parameters and the fuzzy controllers based on backstepping technology is constructed to control the AC drive system with high performance. The main results of the thesis are summarized as follows:1. The adaptive fuzzy control is proposed for a class of single-input-single-output strict-feedback nonlinear systems. During the control design process, fuzzy logic system is utilized to approximate the unknown virtual control signals and the unknown nonlinear functions. Backstepping technology is used to construct adaptive fuzzy controllers for the systems and the Lyapunov method is employed to analyze the stability of the closed-loop system. The proposed method guarantees the boundedness of all the signals in the resulting closed-loop system and gains good tracking performance. It is worth pointing out that the proposed scheme has a simple structure and less adaptive parameters, which will alleviate the computational burden of the scheme and render the developed scheme more suitable for practical applications.2. The problem of speed and position tracking control for Permanent magnet synchronous motor is proposed based on backstepping technology. Fuzzy logic systems are used to approximate the nonlinearities in order to overcome the system uncertainties of modeling and parameters. Adaptive backstepping technique is employed to construct controllers and the Lyapunov method is employed to analyze the stability of the system. The proposed adaptive fuzzy controllers guarantee the tracking error converges to a small neighborhood of the origin and good tracking performance even with the existence of the parameter uncertainties and load torque disturbance. Simulation results illustrate the effectiveness of the proposed control scheme.3. For the problems of parameter uncertainties and load torque disturbance of induction motor, an adaptive fuzzy scheme of speed and position tracking is developed for induction motor based on backstepping technology and the Lyapunov theory. Fuzzy logic systems are utilized to approximate the nonlinear functions and virtual control functions, the adaptive technology is combined to estimate the unknown parameters. Furthermore, the fuzzy controllers are contructed for the drive system based on backstepping. It should be pointed out that the proposed scheme has a simple structure and less adaptive parameters. So it will be easy to be implemented in practice. And also the controllers can guarantee the boundedness of all the signals in the closed-loop system and good tracking performance even existence of parameter uncertainties and load torque disturbance. Simulation results demonstrate the effectiveness of the designed control program.4. The question of controlling chaos in the Permanent magnet synchronous motor is addressed based on the adaptive fuzzy backstepping technology technology. The dynamic model of PMSM full of nonlinearity and multivariate maybe appear Hopf bifurcation, limit cycles and chaotic attractors with systemic parameters falling into a certain area. The chaotic behavior in PMSM is undesirable since it can extremely destroy the stabilization of the motor even induce drive system collapse. For this matter, adaptive fuzzy technology is exploited to control the chaos of the PMSM drive system. Fuzzy logic systems are used to approximate the nonlinear functions and the fuzzy controllers is constructed for the drive system to remove chaos phenomenon. Compared with the conventional backstepping, the designed fuzzy controllers’ structure is very simple and easy to be put into practice. Simulation results illustrate that the proposed control scheme forces the output of the controlled system to follow the tracks of the given speed and position signals well.