Research On Position Sensorless Vector Control Scheme Of Asynchronous Motor

Asynchronous motor has the advantages of simple structure,low maintenance cost,durability,reliable performance,strong adaptability to the environment and so on.It has become the main force in industrial applications.However,it has the following disadvantages: the model is nonlinear,influenced by the parameters,the load torque disturbance is unknown,resulting in the asynchronous motor control complex.Because the motor speed and Angle position information are not suitable for measurement,the sensorless position technology has become a research hotspot.The main content of this paper is sensorless vector control technology of induction motor based on extended Kalman filter(EKF).Firstly,the vector control technology is introduced.The mathematical model of induction motor is established,and the equations of state under two coordinate systems are derived by using the model.By comparing three kinds of flux orientation,the vector governing equation was derived by selecting rotor orientation,and the parameter design of regulator,SVPWM and discretization technology are introduced.Secondly,two sensorless control algorithms are introduced.The first is a hybrid model,in which the calculation steps are given,the PI regulator parameters are designed and the formula of speed estimation is derived.The second is EKF algorithm,introduces the principle of Kalman filter(KF).By discretization and linearization of KF,the EKF algorithm suitable for nonlinear motor system can be obtained.The coefficient matrix of EKF is derived by the state equation in ?-? coordinate system,and the calculation steps of asynchronous motor EKF are summarized.By using the sensitivity of stator resistance to compare and analyze the two algorithms,it can be concluded that the estimation accuracy of EKF is high and the anti-interference is strong.Therefore,an in-depth study on EKF was conducted.The initial values of traditional EKF are selected to verify the open loop and closed loop performance of the system,and the sensitivity analysis of rotor resistance is carried out.Then,the third order EKF is derived from the state equation in d-q coordinate system,aiming at the shortcoming of the traditional EKF.After parameter sensitivity analysis,it is found that after EKF descending order,the calculation amount is greatly reduced,the system running speed is accelerated,but the system performance is reduced.Therefore,the strong tracking algorithm(STF)is used to optimize the thirdorder EKF,and the residual selection of STF is optimized.Finally,the asynchronous motor double closed-loop control system is built on the Matlab/Simulink simulation platform.The sensorless control algorithm is added,and the waveform such as speed and flux flux is derived.The dynamic and static performance of each algorithm is analyzed to verify the effectiveness of the algorithm.TMS320F28335 chip was selected for experimental verification on the asynchronous motor frequency conversion and speed regulation experimental platform.The vector control experiment of induction motor is carried out to verify the rationality and practicability of double closed loop and sensorless algorithm.