Research On Speed Identification Of Induction Motor In Vector Control System Based On Improved MRAS

As a simple structure power machinery, the induction motor has the advantages of low manufacturing process, saving cost and running more reliable, and it is widely used in various industries. However, with the deepening of the research,based on the principle of vector control, for asynchronous motor AC drive system and AC servo control system of the increasingly high demand. The system reliability can be improved and the hardware cost can be also reduced when using the speed identification structure to replace position sensor. However, the premise of replacing the position sensor is the need for accurate speed identification, the motor speed identification of the following aspects will be studied in this paper.From the perspective of the motor mathematical model, according to the principle of vector control, a simulation platform is built based on the rotor field oriented induction motor vector control system using Simulink,and this platform is simulated. In this paper, the method of parameter identification is introduced, and the model reference adaptive(MRAS) algorithm is studied. The adaptive law of speed identification based on Popov’s theory is derived.Based on the MRAS algorithm, an improved algorithm based on the elimination of the integral is proposed, which can effectively eliminate the influence of DC deviation and integral saturation caused by the voltage pure integral, and the improved algorithm is composed of the position sensorless control system of small signal analysis and modeling, based on root locus determines the system stability.The simulation results show that improved MRAS method to make up a closed-loop control system based on the given speed and full load range is stable. In addition,the sensitivity analysis of the parameters sensitivity of the improved MRAS speed identification system is carried out, and the simulation results show that the change of the motor parameters can have a effect on the identification of the convergence speed.The MRAS and improved algorithm of speed and mutation load and torque test comparison, simulation and analysis. The simulation results show that the improved identification algorithm of higher accuracy and smaller overshoot.The whole experimental platform is built, and the sampling circuit of welding voltage and current is designed. Dave 3 as the software development platform in XMC4500, design the algorithm to achieve the main program and interrupt service program, eventually in the experimental platform is built to verify the MRAS and improved algorithm. The results show that the improved algorithm of identificationresults with smaller overshoot, faster response and accuracy higher.