Research On Parameter Identification Of Asynchronous Motor And Speed Sensorless Control Technology

Asynchronous motors are widely used in the field of drive control because of their many advantages,such as simple structure,low cost,easy maintenance,wide speed range and operation in harsh environments.In an asynchronous motor speed closed-loop control system,it is necessary to use position sensors to collect information for speed measurement to improve motor control performance.However,the installation of the sensor complicates the structure of the motor and reduces its reliability,and its impact is more pronounced in harsh environments.In order to improve the operation reliability,the speed sensorless control technology is studied to further improve the motor control performance.In addition,in the vector control of asynchronous motors,the accuracy of the motor parameters will directly affect the orientation of the magnetic field,which will reduce the performance of the vector control system of the asynchronous motor.In this paper,based on vector control,the research on asynchronous motor speed senssorless control technology and parameter online identification method is carried out.The main research contents and achievements are as follows:(1)Analysis of research status at home and abroad.To study and analyze the current parameter identification method and speed sensorless control technology of asynchronous motors,a model reference adaptive(MRAS)for online parameter identification and speed sensorless control method is proposed.(2)Modeling of asynchronous motor vector control system.According to the principle of coordinate transformation,the mathematical model of the asynchronous motor in rotating and stationary coordinates is simplified,and the decoupling of the excitation component and torque component of the asynchronous motor is achieved.Adopt SVPWM modulation technology and build an asynchronous motor vector control system based on rotor flux observation.(3)Analysis of the influence of parameter changes on the vector control of asynchronous motors and dead zone compensation.The effects of changes in the stator resistance under the voltage model and the rotor time constant under the current model on the amplitude and phase of the winding flux linkage are studied,and the online identification of the parameters based on the MRAS method is proposed.Research on dead time compensation strategy.The first-order low-pass digital filter is used to filter the current feedback signal to reduce the torque ripple.(4)The MRAS method based on rotor flux linkage is used to identify the speed and parameters.An adaptive law that can satisfy the stability of the parameter identification system is designed.Since the rotor flux linkage observation is affected by the stator resistance,a reference adaptive method based on excitation reactive power model is proposed to eliminate the error caused by the temperature change of the stator resistance.In order to better simulate the actual environment,by changed the rotor time constant amplitude Simulation experiments were carried out on the size,and the results of the simulation experiments showed that when the rotor time constant is abrupt,the identification parameters can quickly follow the system given value in a short time and are not affected by the change of the stator resistance,which proves the feasibility and effectiveness of the proposed method.