Research On Control System Of Asynchronous Motor

VVVF are the main mode of asynchronous motor speed control system. But the inverter output has high harmonic content in the traditional control system and had adversely affected for power and speed control system, so high-performance frequency converter must be needed. Asynchronous motor is a multivariable, nonlinear, strong coupling of time-varying parameter system, it is difficult to use precise mathematical modeltodescribe, and the induction motor control system is often subject to various disturbances. To get high-performance induction motor inverter system, it is necessary to applicate modern control theory. Therefore sliding mode variable structure control is used in this article.The research work is mainly application of sliding mode variable structure control in Induction motor vector control system in this paper.First of all, after the analysis of theses five-level inverter types and the advantages and disadvantages, the diode-clamped five-level inverter is carried out for an in-depth analysis. And according to the type five-level inverter output analysis, SVPWM control algorithm is used to control inverter. It has severl switch states for the same space vector,the principle of soused on each side is used to determine the slip state of the main device switches. In order to improve the utilization of DC power supply, the five-level inverter output has been modulated treatment, and modulation algorithms have been simulated.Secondly, the rotor magnetic field oriented vector control principle and realization in asynchronous motor speed control system is clarified, based on the three-phase squirrel cage induction motor dynamic mathematical model. slide-mode variable structure control is such a strategy that is characterized of low mathematical model precision,insensitiveness to system parameter variation and external disturbances, omission of parameter identifications, fast dynamic response and easy implementation. These advantages make it suitable to. high performance vector controlled asynchronous motor drives. A sliding mode variable structure speed controller is designed to enhance three-phase squirrel cage induction motor vector control system of anti-interference ability and robustness.the sliding mode variable structure control algorithm is verified by simulation and the result is perfect.