Study Of Speed-Sensorless Field Oriented Control For The Induction Motor Based On DSP

The AC motor speed controlling is a complex subject, it includes the knowledge of many other subjects such as the electric and electronic technology, the control engineer, the computer and the induction motor etc. The realization of the good performance AC control system is a hard work. This is because the AC motor is a strongly-coupled nonlinear system with many variables. The torque is not easy to control either. The method of the rotor flux position checking improves greatly the development of motor control system. The induction motor speed-sensorless FOC system makes it much easier to control the system. The FOC control theory realizesthe decoupling of the stator voltage and the torque control. The basic idea is using the coordinate transformation to change the three-Phase system to the two-Phase system and it realizes the decoupling between field current and torque current of the stator current. The method makes it possible to control the flux and current respectively, just like the DC motor. With the development of the electric and electronic technology and the development of computer, high-integrated special modules and high-precision digital signal processor(DSP)are applied to AC drive so that vector control has been developed rapidly.Now, the speed-sensorless FOC is one of the most important developing directions of the motor control system. The FOC control needs to get the accurate position of the rotor flux. It is always through the speed sensor. But if we do that it will result in the degrading of the credibility and adaptability and cost increasing of the control system. So many scholars have paid much attention to the speed-sensorless FOC control method. The speed and flux checking is the key problem. Inthis article, we calculate the speed by using the stator flux searching and improved the result precision.In this article, first we introduce the now state of the motor control development. Then we induce the basic theory of the coordinate transformation. And based on it, we designed an mathematic model by using MATLAB/SIMULINK.