PMSM Speed Sensorless Control Based On Current Regulation And Fault Tolerant Control

In recent years,permanent magnet synchronous motor(PMSM)has been used in a variety of high-end manufacturing industries because of its many advantages.PMSM speed sensorless control technology has received extensive attention from scholars at home and abroad because it does not need to install sensors in the gearbox.However,the existing speed sensorless control technology has the problems of inaccurate and unreliable acquisition of current and voltage information.Therefore,this paper studies some problems in PMSM speed sensorless control.The main contents are summarized as follows:(1)A voltage compensation method based on disturbance observer is designed to solve the voltage distortion of PMSM caused by nonlinear factors in the voltage source inverter(VSI).The nonlinear VSI factors in the stator and rotor coordinate systems are first studied and modeled.The disturbance voltage caused by the non-ideal switching characteristics of IGBT is then compensated to the d-q axis current loop in a feedforward manner in real time,reducing the error between the command voltage of PI controller and the actual output voltage of VSI,and thus improving the dynamic and steady-state performance of PMSM vector control and speed sensorless control.(2)A PMSM speed sensorless control scheme based on d-axis variable structure current controller is proposed to solve the problem that the d-axis PI controller is sensitive to changes in motor parameters under the i_d=0 control strategy.The continuous function is then introduced as the exponential approach rate to improve the discontinuous symbolic function in order to reduce the chattering effect in sliding mode motion.Finally,two classic speed sensorless algorithms are used to verify it:the model reference adaptive(MRAS)observer and the sliding mode observer.The proposed scheme achieves better speed estimation performance when the stator resistance and speed change,according to simulation results.(3)A fuzzy PI adaptive control scheme based on double closed-loop speed and current is proposed to solve the problem of fixed gain of PI controller in double closed-loop control strategy.First,the speed and current controller has been upgraded to a fuzzy PI adaptive controller,which improves the accuracy of current and voltage data acquisition even more.A switched PI adaptive mechanism is then proposed to solve the problem that the MRAS observer has fixed gain and is difficult to work consistently under variable working conditions.By setting different thresholds,the system can choose the appropriate PI adaptive mechanism based on the amplitude of the current error variable,improve the identification accuracy of stator resistance R_s,and further strengthen the robustness of PMSM sensorless control under parameter perturbation.(4)A PMSM speed sensorless control based on current sensor fault-tolerant control is proposed to solve the problem of obtaining an accurate current signal after the current sensor fails.To improve the robustness of current estimation,the extended state observer is used to identify R_sand iterate it into the estimation equation of d-q axis current.The Popov hyperstability theorem is then used to derive the inductance and flux parameter identification equations.Then,in the MRAS observer,the traditional PI adaptive mechanism is improved to a super spiral algorithm,and an error correction term is introduced to complete the closed-loop estimation,allowing the observer to improve its speed estimation accuracy while reducing chattering.Finally,the identified parameters and estimated current are fed into the MRAS observer that has already been built.The proposed scheme’s effectiveness is confirmed by simulation experiments.