Research On Rotor Time Constant Identification Of Induction Motor Based On Rotor Field Orientation

Because of its simple structure and good speed regulation performance,induction motors are often used in electric vehicles and CNC machine tools.In the control strategy of induction motor,the rotor field oriented vector control system can decouple the excitation current and torque current,which is an ideal control strategy for high performance speed regulation of induction motor.However,in the rotor flux oriented control strategy based on current model,the change of motor parameters,especially the rotor time constant,will affect the observation of the phase angle of the magnetic field,resulting in the deviation of the rotor flux orientation and the oscillation of the output torque of the induction motor.In this paper,on the premise of fully understanding the research status at home and abroad,in order to develop a high-performance vector control system of induction motor,we carry out the research on the related problems with the correction of rotor time constant as the main content.Based on the mathematical model and coordinate transformation of induction motor,the rotor magnetic field orientation control system of induction motor is introduced.The simulation results show that the system has good dynamic and static performance on MATLAB/SIMULINK platform.The main factors that influence the phase observation of rotor magnetic field are discussed.The influence of rotor time constant on the rotor magnetic field orientation control system is analyzed.Based on the traditional off-line identification method of rotor time constant,the method of rotor time constant off-line identification based on recursive least square algorithm is studied.By using the linear model of least square algorithm,the second-order filter is reduced to the first-order filter,which avoids the second derivative after the filtering signal.The simulation results show that the identification effect based on least square method is better than that of traditional identification method.On the basis of off-line identification,the rotor time constant is identified online.A model reference adaptive system is constructed by using stator current and point multiplication of stator flux as the setting physical quantity,and the observer of stator flux without considering DC bias is improved.A new method of rotor time constant identification based on flux chain optimization model is proposed.The simulation results show that the method has high identification accuracy.Finally,the experimental test platform is built,the software design of theoretical algorithm is carried out,and the program flow chart is given.The vector control and parameter identification experiments are carried out for a 3.7k W induction motor,which verifies the feasibility of the relevant algorithm.