Research On Vector Control System Of Permanent Magnet Synchronous Motor

As the mainstream of power source in today's digital machine tools and intelligent robots,permanent magnet synchronous motor(PMSM)'s development is closely related to the progress and breakthrough of rare earth permanent magnet materials,digital signal processing methods,power electronics technology and new motor control theory.With the promotion of permanent magnet synchronous motor,methods to control it has become the focus and hot spot in the field of AC motor control,among which vector control is the most common.In this thesis,basic knowledge of permanent-magnet synchronous motor and its mathematical model in different coordinate systems are firstly introduced,which include the structural features of permanent-magnet synchronous motor and the major transformations in the three kinds of coordinate systems,by which,the fundamental equation and space state model in the three coordinate systems are deduced.And then,based on the mathematical model of synchronous motor under d-q rotating coordinate system,the basic theories of vector control are analyzed,deduction of space vector modulation and design of current loop controller are completed.Secondly,at the end of Chapter ?,various types of field current control methods are analyzed.And through comparison of various control methods,the field-oriented control method applied in this thesis is selected.On such basis,several types of permanent-magnet synchronous motor speed outer-loop controllers are designed in this thesis,including PI speed controller,improved PI speed controller,sliding mode speed controller and improved sliding mode speed controller.PI speed controller is designed on the basis of classic control theory;the improved PI speed controller is provided with improvement on saturation in the integral element,which is of anti-saturation effects.Sliding model controller is designed on the basis of modern control theory;and the improved sliding model controller is provided with a optimization design of sliding mode plane switching function for the problem of large torque fluctuation of the sliding mode speed controller in steady state in order to reduce the torque fluctuation.Finally,a simulation test of the vector control system of permanent-magnet synchronous motor with different speed controller is conducted and an analytical summary is presented from the three aspects of rotate speed in dynamic state,steady state and torque in steady state according to the simulation results.It is shown by the simulation test in this thesis that,the sliding mode controller has absolute superiority in rotate speed dynamic response to the PI controller.To be specific,the improved sliding mode controller can effectively solve the problem of large fluctuation in torque in steady state of common integral sliding mode controller while maintaining the advantages of common integral sliding mode controller,which include quick dynamic response and zero overshoot.