Speed Sensorless Control Of Induction Motor

With the development of electric propulsion techniques, various control techniques for AC servo motors has been proposed. Among them Vector Control technique was developed as a new AC motor drive control system in the last decades. Vector Control System attracts more and more attention for it can convert complex AC motor into equivalent DC motor model, then we can imitate many effective control strategies for DC motor to achieve perfect performance. The technique can make the nonlinear, complex, strong coupling induction motor drive easier to control.Speed sensorless control techniques can make the hardware simple and improve the reliability without the lumbersome velocity sensor, and it becomes more and more important in the modern AC servo drive. It is one of the attracting research directions in the high-precision servo control field because of its robust characteristics, simple realization and excellent dynamic response. Several common rotor speed estimation was introduced in the paper. The technique of rotor speed estimated by Speed observation estimation was introduced emphasized. The basic principle of Vector Control System and the nonlinear mathematical model of induction motor are first presented. Then the sensorless control for induction motor is developed in detail. A high-precision speed estimator and a new second-order control scheme are formulated to solve the high-precision sensorless control for induction motor, based on the favorable results obtained by Marino et al. The global asymptotic stability of the closed-loop system with the induction motor dynamics is proposed in agreements with Lyapunov's direct method. Computer simulation performed on a three-phase single-pole pair induction motor demonstrates the improved performance of the proposed approach, including the fast response, simple implementation.