Research On Dynamic Performance And Robustness For Sensorless Controlled Pmsm Drives

Sensorless control could improve the robustness of permanent magnet synchronous motor(PMSM)drive and reduce the cost,which has been widely applied in wide industrial fields.Through the researches in the past few years,sensorless controlled AC motor drives has made great progress,and has been successfully applied in many occasions.However,As the high accuracy and dynamic performance is required in applications,sensorless control needs to be further investigated.To meet these requirements,this dissertation focuses on the key techniques concerning the robustness and dynamic performance improvement of sensorless control drive,including current predictive control,rotor position estimation and flux-weakening control,etc.The current predictive control can effectively solve the influence of the crosscoupling term and the delay in the current loop to improve the current control performance,which could expand the bandwidth of the current loop.However,measurement errors and variation of motor parameters cause a static current error.In this paper,a static current error suppression strategy based on the SVM predictive control is proposed to overcome the problem of system efficiency reduction,weakening of torque output capability and difficulty of torque control mode caused by the static error in the d-q axis current.In view of the deviation between the parameters of the predictive controller and the actual parameters,the negative effects of the control system stability are analyzed.In addition,the quantitative relationship between static current error and model parameter error is established to study an effective static current error elimination method.This method corrects the parameters of the predictive control model by the cross-axis feedback current,which is applied to eliminate the static error caused by the parameter error of the motor model.Finally,the reliability and effectiveness of this method are verified by experiments.Initial rotor position detection is the basis of sensorless control for PMSM drives.Considering that the traditional DC orientation method will force the rotor to rotate before startup,a parameter tuning method based on extended state observer(ESO)for detecting the initial position of rotor at still is proposed.Aiming at the issues of obvious current ripple,torque ripple and voltage error caused by nonlinearities of inverter in high-frequency rotating sinusoidal voltage injection,an improved highfrequency square-wave voltage injection method is proposed,which effectively reduces the initial position identification time and improves position detection accuracy.Considering that the traditional proportional-integral(PI)observer has slow convergence speed,and the differential operation of the proportional-integraldifferential(PID)or proportional-integral-integral-differential(PIID)controllers can introduce large noise to the drive system,which makes it difficult to configure parameters,a parameter tuning method based on ESO is studied.ESO estimates state variables quickly and accurately,and it has a higher bandwidth.ESO can effectively avoid the amplification effect of differential operation on noise and improve the performance of position estimation by integrating operation to estimate state variables.To realize sensorless vector control of PMSM in high speed operation,it is necessary for PMSM to operate in the deep field weakening area.A sensorless flux weakening control strategy based on voltage phase angle control is proposed.In the high-speed range,the current regulator has integration saturation problem,and there is the output voltage saturation phenomenon.At the same time,the current crosscoupling effect becomes more serious,and the exciting current and the torque producing current need to be properly distributed.To solve this problem,the voltage angle control method can not only solve the problem that the two current regulators conflict with each other,but also has the advantage of maximally utilizing the DC link voltage.This flux weakening method has higher stability in the deep field weakening region.In order to further improve the performance of flux weakening,it is essential to reduce the current ripple in the voltage phase angle control method to improve the stability.In this paper,a method based on the voltage phase angle control strategy is studied to reduce current ripple and frequency compensation.As the flux weakening control strategy based on voltage phase angle control cause more current ripple than the traditional method,an effective method of suppressing ripple is proposed to reduce current noise and torque ripple,and a frequency compensation method is proposed to improve the stability of motor operationOn the basis of the above research,a prototype of general industrial sensorless PMSM drive with integrated sensorless control method was developed.The digital control algorithm is implemented in the ARM chip.The experimental results verify the effectiveness of the proposed method.