Research On The Speed-sensorless Vector Control System For Induction Motor

In recent years, with power electronic technology, microelectronics technology progress and the rapid development of modern control theory, based on this induction motor speed control technology also has made good progress. As is known to all, induction motor is a multivariable and high order, close coupling nonlinear systems, unlike dc motor so easy to control torque, vector control technology in speed control and torque control makes speed system can communicate with dc speed control system, and comparable speed sensorless vector control technology because it can save speed sensor, make corresponding ac drive system becomes simple, reliable, also cut costs, so has become the hotspot in recent years.It firstly discussed in three-phase asynchronous motor static coordinate system, two-phase static and revolving coordinate motor basic dynamic mathematical model of induction motors, analyzed according to the rotor field-oriented vector control methods and rotor flux of open loop speed sensorless vector control scheme. Flux observing speed sensorless system is the core technology, for voltage model rotor flux observer, pure integrator easily lead to output signal saturation and dc offset voltage, based on detailed model rotor flux observer is observation error causes on the basis of several classic integral, the improved scheme theory analysis, comparative simulation. Pointed out that their initial value only for integral improved, has failed to effectively solve the input dc shifts problem. Based on this, the paper proposed the improvement of pure integrator of sampling signal while eliminating the stator current dc offset, so as to solve the input dc bias problems.Meanwhile compares some speed sensorless speed estimation methods, including direct speed estimation and indirect speed estimation, using the difference and synchronization by turn of speed of angular speed indirect estimates. The paper to the whole governing system simulation software is simulated, and the simulation results show that speed estimation algorithm is correct, high accuracy; speed by using this method of the drive system has a good dynamic and static performance.Speed sensorless vector control system control performance depends largely on the speed regulator and current regulator PI parameters. Papers on the basis of known motor parameters, current loop is decomposed into two independent system, realize dynamic fully decoupling. Design the speed and the current PI adjuster, realized the vector control system PI parameter self-setting. The simulation and experiment results show that using this method the control system design regulator has good static, dynamic performance.Finally, this paper established based on DSP digital control of induction motor speed sensorless vector control system. In order to improve the calculation accuracy, what value based on motor marked the mathematical model control system software design. Experimental results show that the designed by speed sensorless vector control system has good dynamic and static performance.