Research On Speed Sensorless Vector Control Of Induction Motors

In terms of speed and torque control, based on vector control AC speed control system has good control effect, the speed sensorless technology simplifies the AC speed control system, enhance the adaptability of the system and reduce system cost. The combination of speed sensorless technology and vector control technology became a research focus. Based on this, the thesis carries out an in-depth research on speed sensorless vector control system of induction motor.Firstly, research on the basic theory of vector control, including the vector coordinate transformation and the mathematical model of induction motor in different coordinate system. And then combined with the field oriented method, the technology of field oriented control and flux signal detection, designed the vector control system of induction motor based on rotor field oriented. Finally the control principle and algorithm of SVPWM technology are analyzed.Combined with the characteristics of model reference adaptive system(MRAS), the speed estimation of vector control system of induction motor is studied. Based on the traditional model reference adaptive system, a speed estimation model of variable parameter is designed. The accuracy of vector control system is affected by the flux observation, through the analysis of basic flux observers, a combined model of rotor flux observer has been designed.Combined with the research on speed sensorless vector control system, a hardware and software of speed sensorless vector control system based on the TMS320F240 DSP is designed. The hardware circuit mainly includes the main circuit of the system,the detection circuit and the control circuit. The software design includes the main program and the interrupt service program.The model of each part of the system is built by the Matlab/Simulink, and then the model is simulated combined with the theory of model reference adaptive speed estimation. Simulation results show that the method of MRAS speed estimation based on variable parameter has a high accuracy, a good convergence and good performance on the speed sensorless vector control system of induction motor.