Research On Advancedcontrolstrategy And Application Of PMSM Drive System

Because of the superior performance of the Permanent Magnet Synchronous Motor,it is widely used in industry,scientific research and daily life.Therefore,it is of great theoretical significance and practical value to study the advanced control strategy of permanent magnet synchronous motor drive system with high performance.The domestic and foreign studies about the field of PMSM control are so large.The main control strategy of PMSM includes vector control and direct torque control.So far,the research of vector control,including the basic theory and control method,has been relatively mature.The direct torque controlhas been successfully applied to the asynchronous motor and PMSM,but its basic theory is far from perfect compared to the vector control.In addition,the application ofvariable structure sliding mode control in the field of motor control is becoming more and more widely.Considering these factors,the main research contents of this thesis are as follows:Firstly,the control principle of the PMSM and the research status at home and abroad are summarized.Then,the mathematic model of PMSM in different coordinate systems is analyzed.And the control methods of PMSM applied to different occasionsare analyzed in detail,including thezero d-axis current control,the unity power control and the maximum torque per ampere control.The three control methods are suitable for vector control and direct torque control.Because of the inherent shortcomings of traditional direct torque control such as large torque ripple and variable switching frequency,the traditional direct torque control strategy is improved in this thesisand a non-constant stator fluxamplitudereferencecontrol method for PMSM based on the space vector modulation is studied,which can reduce reactive power loss and improve the efficiency of PMSM.The simulations about the improveddirect torque control compared with the traditionaldirect torque control are analyzed.And the simulation results verify the effectiveness of the improved direct torque control.To extend the high-speed operation range of PMSM,a field-weakening control is analyzed,which is divided into three stages according to the speed of the motor,including the maximum torque per ampere control,the constant power speed range control and the maximum torque per voltage control.And the drawing methods of each curve are given in detail.The direct torque control still depends on the stator resistance of the motor,which will affect the accuracy of the stator flux estimation when the motor is running at low speed.So the thesis studiesanintegralsliding mode control strategy based on the permanent magnet synchronous motor direct torque control,which uses the sliding mode controller to replace the hysteresis controller of the traditional direct torque control and enhances the system robustness to various disturbances.And for the sake of improving the speed of convergence,the product part of sliding mode control is added in the controller to enhance the transient performance of the system.Finally,an experimental platform of PMSM control system based on the processor of TMS320F2812 is built and some experiments are done.