The Study Of Vector-controlled System For Induction Motor By Stator Voltage Decoupling

Three-phase induction motor is a non-linear, multivariable, high-order and close coupling system. It's torque isn't controlled as the DC motor. But induction motor is controlled as the DC motor by vector control .While sensorless vector control technique can makes the relative inductor motor drive easier, more economical and more reliable. For this reason.the sensorless vector control is becoming the more important researching project.Firstly, the dynamic mathematical model of inductor motor is analysised and studied under static reference frame. Then through coordinate transforming, the mathematical model of inductor motor in terms of flux linkage is deduced. The rotor flux linkage control and torque control based on the rotor field orientation control are separately achieved.Secondly, based on the rotor field orientation vector-controlled, Error signal of the stator M, T-axis current in the synchronous reference frame is utilized to attain the induction motor voltage compensation. And error signal of the stator T-axis current is utilized to attain the induction motor speed, This speed estimation method is simple and has self-adaptability. Because classical PI controllers is used, the structure of the sensorless vector control is very simple.Thirdly, based on MATLAB , a simulation model of the proposed vector control sysem is established. In this model, because of adopted PU of controlled variables, the system has high self-adaptability and parameters of PI controller are easy to be adjusted; The simulation model is a discrete control system and in this system sample period of different signal is different; To improve the system dynamic and static performance ,a compensation method of the phase shift caused by discrete system is presented .Finally,dynamic and static characteristic of induction motor are simulated. Simulation results demonstrate that the proposed vector control system is feasible and valid.