Study On Position Sensorless Induction Motor Servo System

AC induction motors are widely used in high-performance servo systems because of their simple structure,low price and easy maintenance.Moreover by using the advanced control technology,they can have good static and dynamic performance.Induction motor servo systems require fast dynamic response,good anti-interference ability and robustness for the parameters change.One of the keys which limit the above factors is the postion / speed sensor. Therefore,the research on sensorless speed control of motor has become a hotspot.This paper introduces a sensorless induction motor servo system based on DSP.With the TMS320LF2407A of TI company as core chip,this paper adopts field oriented control and the extended Kalman filter arithmetic.The main tasks are included in this paper as follows:Firstly,the paper analyzes the development of sensorless control of induction motor technology.After comparison of several control strategies,sensorless field oriented control is choosed and the extended Kalman filter arithmetic is proposed to develop this project.Secondly,with discussing the principle of vector control,the mathematic model of AC induction motor in two-phase rotating coordinates is educed from three-phase coordinates by Clarke transform and Parke transform.Based on the rotor field oriented theory,the stator's currents are decoupled suitably.The article also focuses on the illustration of the principle of EKF,and deduces the EKF equations of induction motor in theα-βcoordinate.Combination of the EKF algorithm for rotor position and speed estimation,it realizes a sensorless vector control system and gives the control structure diagram of this system.Lastly,with DSP as core chip,this paper designs the drive system's hardware and software. Moreover a system experiment platform is built aiming at a 2.2kw induction motor.The software is implemented by assembly language.Finally a fully digital motor control system is realized on sensorless field oriented control.The debugging results of motor's real operation are given and analyzed in the end of the paper.The experimental results show that this control system has characteristic of fast response, fine dynamic behaviour,strong anti-disturbance and good control performance.Moreover the reasonability and validity of the EKF arithmetic for rotor speed estimation have been testified. It confirms practical value of application on low-cost and high-performance control system.