Research On Speed Sensorless Vector Control System Of Induction Motor

Speed sensorless control has the advantages of reducing hardware cost,reducing signal interference,simplifying system structure and high reliability,and is widely used in industrial production.In order to improve the reliability of speed sensorless control system,the adaptive observer is studied and the performance of speed estimation is improved,which improves the stability of control system.The motor parameters will affect the magnetic field orientation in vector control,and the inaccurate parameters will lead to the performance degradation of the vector control system of asynchronous motor.Based on the field-oriented control,this paper studies the speed sensorless vector control system and parameter identification of induction motor.The main research work of this paper is as follows:1.The development history of asynchronous motor control technology is briefly described,and the common motor speed estimation methods are compared.Then the mathematical model of the motor is analyzed and studied,and the basic principle of vector control is described.According to the mathematical model,a feedforward decoupling vector control system is established,and the PI parameter design method of the current loop and the speed loop of the asynchronous motor is described.2.The speed estimation method based on the full-order flux observer is studied,and the stability of the full-order observer is analyzed in depth.In order to improve the speed adaptive performance,the feedback gain matrix is used to make the pole of the observer on the left side of the pole of the asynchronous motor,which accelerates the convergence of the observer and improves the stability of the observer when the stator current frequency is low.The feedback gain matrix uses the pole shift left method and the pole multiple method,Reduce the state variable error between the observer and the motor.The influence of the flux linkage error caused by the stator current excitation component error on the speed estimation is analyzed,and the excitation current error is introduced into the speed adaptive law.Secondly,the digital discretization method of the observer is introduced.3.Because the inaccuracy of stator and rotor resistance parameters will cause errors in speed observation and flux estimation,the parameter identification based on full-order flux observer is adopted,and the influence of stator and rotor resistance parameters on indirect magnetic field orientation is analyzed.The adaptive law of stator and rotor resistance is deduced by Lyapunov stability theorem,which realizes the identification of stator without speed sensor The rotor resistance and the rotor resistance are identified simultaneously at high speed.