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

Induction motor has made great development both in the physical structure and the controlmethods so far. Domestic and international scholars have never stopped research on the controlmethod of induction motor, such as the VVVF control, the direct torque control system and thevector control system. The vector control system has been favored by the majority of scholarswith it’s simple structure, good control performance.The vector control system is based on the the coordinate transformation theory. We cansimplify the mathematical model of induction motor by using coordinate transformation. Alsowe can separately control flux and torque by decoupling the strong coupling model of theinduction motor, so the speed control of it becomes better. The merits of vector controlperformance relies on the closed-loop speed control system, and speed is usually measured bythe speed sensor directly or got from the mathematical model of induction motor. The existenceof the speed sensor increases the cost of hardware and it will also be affected by external harshenvironments or the concentricity of induction motor. Therefore, people pay more and moreattention to the speed sensorless vector control.In this paper, the parameter identification method of MRAS (Model Reference Adaptive) wasused to achieve speed sensorless vector control. it includes the following main contents: Firstly,uses the rotor flux oriented vector control and SVPWM (Space Vector Pulse Width Modulation)to complete the basic vector control system; Secondly, estimates it’s speed and flux by theparameter identification method of MRAS, combined with the first step to establish the doubleclosed loop speed loop and flux loop speed sensorless vector control system; Finally, bymodifying the reference model and adjustable model, an instantaneous reactive power modelbased MRAS without integration and rotor resistance is gained on the analysis of basic principleof MRAS.TMS320F2812was used to complete the design of hardware and software. And get outputwaveform of this experiment from the oscilloscope. The results show that, the improved MRASspeed sensorless vector control system has good start and steady state performance.