Research On Parameter Identification Of Asynchronous Motor Based On Inverter Device

In modern AC motor speed control technology,magnetic field oriental control can decouple the torque component and excitation component of stator current according to the parameters of asynchronous motor,and realize the control method similar to that of a DC motor,which effectively improves the control performance of asynchronous motor.The accuracy of the parameters will affect the degree of decoupling,which in turn affects the performance of the control system.Therefore,the identification of motor parameters plays a fundamental role in the high performance control of motor.Aiming directly at the issue,in this thesis,theoretical analysis was established from the two aspects:the initial value of offline identification acquisition parameters and the change of online identification tracking parameter.The feasibility and accuracy of the parameter identification method were both verified using MATLAB simulation and through experiments.Firstly,based on the coordinate transformation and the dynamic model of asynchronous motor,the motor model under the two-phase coordinate system was deduced,the principle of direct magnetic field orientation control according to the orientation mode of rotor magnetic field is expounded,the principle of spatial vector modulation method was analyzed,and the calculation method of spatial vector action time was also given.Secondly,the principle of parameter identification of asynchronous motor was analyzed.Based on the steady state mathematical model of asynchronous motor,DC motor experiments,single-phase AC experiments and no-load experiments were carried out on the hardware platform to identify the initial values of the motor parameters and quickly establish the motor model required for the field-oriented control system.Aiming directly at the motor parameters variation,the motor parameter identification model based on recursive least squares method is established for online identification,to update asynchronous motor parameters in real time and improve the accuracy of parameter identification.According to the above method of motor parameter identification,the simulation model was built using MATLAB/Simulink,and its feasibility is verified by simulation.Finally,in order to test the accuracy of the identification method,the experimental platform for parameter identification of asynchronous motor was built,which includes TMS320LF2407A DSP as the core of the loop control and IGBT as the main core of the circuit,and the CCS software package was used to write the program in C language,Interrupt program,communication program,offline identification parameter as well as online identification parameter program and other software programs were used,an asynchronous motor with 22kW was selected for parameter identification of the test object.The experimental results show that the method of identifying the initial value of the offline identification parameters can quickly identify the motor parameters,the identification results have small error compared with the actual values,which satisfies the demand of magnetic field orientation control,the online identification method can update motor parameters in real time,which provides theoretical basis for improving the accuracy of parameter identification.