Research On Position Sensorless Vector Control Of Permanent Magnet Synchronous Traction Motor

With the development of control technology of permanent magnet synchronous motor(PMSM),PMSM has been widely used in rail electric traction.Using sensorless permanent magnet synchronous motor can arrange larger traction power in bogie limited space,and make traction system more reliable,therefore,the position sensorless system in the track traction system has a broader application prospects.Therefore,the research on the control strategy of sensorless permanent magnet synchronous motor(PMSM)in electric traction control system is carried out in this thesis.In this thesis,through the analysis of the main circuit and operation mode of the metro permanent magnet synchronous traction system,the basic structure of the permanent magnet synchronous traction system is determined,the position sensorless torque vector control is determined as the bottom control of the traction system.According to the characteristics of permanent magnet synchronous traction motor(PMSM)with constant DC output voltage and wide speed range,the flux weakening control method of PMSM is studied in depth.According to the principle of minimum stator current,the sensorless permanent magnet synchronous motor(PMSM)can be effectively controlled by using optimization theory and motor vector control theory.Based on this,the current closed-loop control strategy and SVPWM control strategy of traction inverter are designed,and the vector control of traction motor in full speed range is realized.In this thesis,the method of pole position observation for sensorless permanent magnet synchronous motor(PMSM)in full speed domain is studied according to the vector control requirements.Through the comparison of several schemes,it is determined that high frequency pulse voltage injection based on the control of sliding film is used to observe the magnetic pole position at low speed.At medium and high speed,the model reference adaptive method based on sliding film variable structure is used to observe the magnetic pole position.A smooth switching strategy is proposed to avoid oscillation in the switching process,and then the pole position observation in the full speed range is designed.The method of pole position observation in the full speed range is combined with the vector control strategy to realize the vector control of the sensorless PMSM in the full speed range.According to the characteristics of train operation and the vector control algorithm proposed in this thesis,the simulation model of permanent magnet synchronous electric traction is established,the full-speed observation pole position and vector control algorithm proposed in this paper can basically meet the needs of metro traction.