Research On Three-Level Permanent Magnet Synchronous Motor Control Based On Position Sensorless Technology

Permanent Magnet Synchronous Motor(PMSM)is widely used in the fields of industry,railway transportation and electric locomotive because of its high power factor,high control accuracy and fast response speed.However,in high-voltage and high-power situations,the traditional two-level inverters appear to be inadequate due to the influence of the voltage stress of the power switch,while the three-level inverters have greater advantages.At the same time,in some special occasions,the application of the motor system is greatly limited due to the large size of the position sensor,the difficulty of installation,and the increased cost.The sensorless technology solves these problems.In this dissertation,PMSM is used as the controlled object,and three-level space vector pulse width modulation(SVPWM)and sensorless technology are studied.The main research contents are as follows:Firstly,this dissertation consults a large number of related literatures about three-level inverters and no position sensor,and makes an in-depth analysis of the research status at home and abroad.Secondly,set up the vector control system,and analyze the implementation process of the control system.The hardware topology of a diode clamped three-level inverter is designed,and the implementation of traditional three-level SVPWM algorithm is analyzed.A simplified three-level SVPWM algorithm is presented for the complexity of traditional algorithm which requires multi-sector judgments and trigonometric function calculation.The algorithm is further simplified while satisfying the system output,and a simulation model is built to verify the algorithm.Thirdly,the sensorless control of PMSM at medium and high speed is studied.In order to solve the problem of chattering in the estimation process of traditional sliding mode observer,the estimation error becomes larger and affects the dynamic and static performance of the system.In this dissertation,a composite sliding mode observer is designed.The extended nonlinear disturbance observer is used to obtain the estimated back EMF,and the sliding mode observer is designed to obtain the rotor position information and speed.The simulation results show that the new algorithm improves the anti disturbance performance and response speed of the system.Finally,the experimental platform of three-level SVPWM sensorless control system is built,and the hardware circuit and software of the system are designed.The correctness and feasibility of the control strategy and sensorless detection technology proposed in this dissertation are verified by experiments.