Research On Lack-phase SVPWM Technology Of Sensorless Symmetrical Six-phase Permanent Magnet Synchronous Motor

In modern electric drive control systems,more and more engineering control fields with high voltage,high current and high reliability,such as electric vehicles,aerospace and national defense projects,put forward strict requirements for the safe and reliable operation of motors.Permanent magnet synchronous motor（PMSM）is widely used because of its high efficiency and good stability.Multiphase PMSM has attracted more and more attention because it can realize low voltage and high power,small torque ripple and fault tolerance that three-phase PMSM does not have.In many harsh environments,multiphase PMSM sensorless control system has become a research hotspot because of its advantages such as less interference,low cost and small volume.In this dissertation,six relative symmetrical winding PMSM is taken as the research object and its efficient and reliable operation is taken as the research content.The key technologies in its application,such as sensorless detection,fault tolerance vector control and so on.Firstly,the literature and development status of multiphase motor vector control,position sensorless detection and fault tolerance at home and abroad are consulted;At the same time,the mathematical models of six symmetrical PMSM in natural coordinate system,two-phase stationary coordinate system and rotating coordinate system are analyzed,and the dimensionality reduction mathematical models of the motor in each coordinate system after one-phase open-circuit fault is deduced.Secondly,the sensorless vector control system of six phase PMSM is emphatically studied,the working principle of traditional model reference adaptive（MRAS）observer and the construction process of parameter adaptive law are analyzed,and its advantages and disadvantages are deeply analyzed.Aiming at the problem of inaccurate rotor position estimation of the traditional MRAS observer during low-speed start-up process,a MRAS observer is proposed to improve it.The simulation results verify the feasibility and effectiveness of the improved MRAS.Thirdly,the fault-tolerant control of six phase PMSM is studied,and the basic theory of traditional space vector pulse width modulation（SVPWM）is analyzed.At the same time,considering the damage of common mode voltage to motor,this dissertation proposes a lack-phase six phase SVPWM which can suppress common mode voltage,and carries out simulation research.The results verify the correctness and feasibility of the new SVPWM modulation technology.Finally,the improved MRAS observer and lack-phase SVPWM strategy are applied to the symmetrical six-phase PMSM system.The system software programming and hardware design are carried out,the double closed-loop vector control system platform is built,and the experimental research is carried out.The results verify the feasibility and correctness of the sensorless detection method,fault tolerance method and lack-phase SVPWM method proposed in this dissertation.