Research On Common Mode Power Repression And Position Sensorless Strategy Of Six-phase Permanent Magnet Synchronous Motor

With the progress of industrial civilization,permanent magnet synchronous motor(PMSM),as the most important part of electromechanical energy conversion,has attracted extensive attention.Because the traditional three-phase motor can not meet the requirements of high power density or fault-tolerant performance occasions,the polyphase motor has more obvious advantages.Under space vector modulation,high frequency common mode voltage pulse will inevitably occur,and then axial current will flow through the insulation or bearing of the motor,affecting the normal service life of the motor.The motor position sensor will increase the volume cost of the motor control system,and the problem that it cannot work in a bad environment is also urgent to be solved.In this dissertation,a control strategy which can suppress the common mode voltage is proposed instead of the traditional control strategy,and an improved sliding mode observer is proposed instead of the traditional position sensor and the traditional sliding mode observer to detect the motor position and speed.The main research contents of this dissertation are as follows:First of all,consult domestic and foreign literature and related materials,in-depth analysis of the multiphase motor common mode voltage suppression,position sensorless detection and multiphase motor control strategy at home and abroad,so as to lay a theoretical foundation for further research.Secondly,the decoupling control mode of six-phase motor is introduced through the dual d-q transformation and vector space decoupling transformation,and the similarities and differences of the two decoupling modes are discussed.On the basis of the vector space decoupling transformation,the two-vector control mode and the fourth-most vector control mode are introduced.Then,based on the common mode voltage of six-phase PMSM,a space vector modulation method with the function of suppressing common mode voltage is proposed as the vector modulation strategy in this dissertation.According to the column of the common mode voltage amplitude of all space vectors,the limitations of the traditional vector control are analyzed,and the new Space Vector Pulse Width Modulation(SVPWM)and vector action time are given.Thirdly,the traditional sliding mode observer is studied and analyzed,and its chattering problem is improved to improve its dynamic and steady state performance,improve the robustness of the senseless control system based on the position,and improve its dynamic response ability in different speed domain.Fourthly,this dissertation uses the MATLAB/Simulink simulation platform to build the system simulation platform for the above introduced content,and through the simulation analysis of relevant results,it verifies the effect of the new space vector modulation on the common mode voltage suppression,and the accuracy of the improved sliding mode observer for the motor position information extraction.Finally,the hardware platform of six-phase PMSM based on position senseless is built,and the experimental research is carried out.The results verify the correctness and feasibility of the content discussed in this dissertation.