Research On Speed Sensor-less Control System Of AC Induction Motor Based On MRAs

Compared to DC motor, asynchronous motor has the advantages of simple structure, high reliability, durability and capacity, low cost and so on, which makes it widely used in industrial production. For pursuing production efficiency, energy saving and emission reduction, the improvement of speed regulation performance of induction motor is necessary. Vector control technology is an excellent speed control technology, which refer to the control mode of DC motor. To achieve excellent control performance, it controls the excitation current and torque current independently. The speed sensor-less technology, which overcome the application restricts of sensor and enhance the reliability and stability of system, get accentuated attention. The Model Reference Adaptive System(MRAS) has higher identification accuracy and stability, which makes it further explored.This paper begins with the space vector and then the vector control theory is analyzed in detail and applied in the asynchronous motor. In this paper, the vector control scheme based on the rotor field oriented is proposed; the theory and implementation are further explored. At the meantime, the speed sensor-less vector control system based on MRAS is proposed. The speed identification method based on reactive power MRAS is proposed and the system's stability is verified. The speed sensor-less vector control system based on reactive power speed identification scheme is completed by combining with the speed vector control system proposed before.In this paper, the proposed speed identification scheme overcomes the influence of integral drift and stator resistance, which improves the accuracy and robustness of the system. In order to eliminate the noise of the sampled signal, the filter is added. The stability of the system is verified and the adaptive law is designed by using the theory of Popov and the speed identification is accomplished.Using Matlab/Simulink platform to construct the system simulation model, the performance of the speed sensor-less control system is verified. Finally, the software program design of the digital control system is completed on the experimental platform with TMS320F2812 DSP as the control core, and the experimental analysis is carried out. The simulation and experiment has achieved ideal results, which verified the excellent performance of speed identification scheme based on reactive power.