Research On Current Sensorless Technology For Permanent Magnet Synchronous Motors Control System

Permanent Magnet Synchronous Motor(PMSM)is used for high performance speed regulation system due to its well-known advantages.In order to realize the high precision control of PMSM,the feedback control of the current is required,so two phase current sensors should be installed in three-phase Voltage Source Inverters(VSI).Nevertheless,sudden severe failure of phase current sensors would result in over-current malfunction of the drive system.And if there is no protection scheme in the gate-drive circuit,the failure would lead to irrecoverable fault of power semiconductors in VSI,which causes degradation of motor drive performance.So it is indispensable to consider fault tolerant control of phase current sensor.The method of Extended State Observer(ESO)is adopted for study of PMSM drive control system without current sensor in the dissertation.The control strategy of PMSM drive system adopted the dissertation has Vector Control(VC)and Finite Control Set model Predictive Control(FCS-MPC).VC is decoupling control of the torque and flux linkage by coordinate transformation,so making the system have good torque characteristics.FCS-MPC strategy is a control algorithm based on the system model to predict the control variables in the future.The advantage is that it doesn't need complex PWM modulator and reduce torque and flux linkage pulsation,thus improve the dynamic and steady-state performance of the system.The main research contents are as follows:(1)For PMSM drive system with single-phase current sensor,the PMSM sliding mode-model prediction torque control system based on ESO single current observer is constructed.Considering the change in stator resistance,the ESO theory is used to design single-phase current observer,in order to replace the fault phase current sensor,and the phase current and stator resistance are estimated in real time.The model predictive torque control strategy is adopted for PMSM drive system to reduce torque and flux linkage pulsation so as to achieve high performance control of the control system.The sliding mode speed controller is designed based on the exponential function to improve the robustness of the control system.(2)For PMSM drive system with any phase current sensors,the PMSM model prediction torque control system based on ESO current-sensorless observer is constructed.Considering the change of stator resistance,the ESO theory is used to design the current-sensorless observer to estimate the three-phase stator current and stator resistance in real time.The model predictive torque control strategy is adopted for PMSM drive system to reduce torque and flux linkage pulsation so as to achieve high performance control of the control system.(3)For PMSM drive system with any phase current sensors,the PMSM VC system based on double ESOs current-sensorless observer is constructed.Considering the robustness of the change of stator resistance and stator inductance,the double ESO theory is used to design the current-sensorless observer to estimate the three-phase stator current in real time.