Sensorless Control System Of Full Speed Field Permanent Magnet Synchronous Motor

Permanent magnet synchronous motors have many advantages like large starting torque,easy control and energy saving,which have been widely used in motor drive systems.Accurate rotor position information measured by mechanical components such as photoelectric encoders and hall sensors is needed in high-performance control.However,the introduction of traditional position sensors increases the complexity of the control system,and which is difficult to operate reliably under harsh conditions.Therefore,position sensorless control technology has become a research hotspot of scholars from all over the world.This thesis mainly studies the position sensorless control of permanent magnet motor in full speed domain.Firstly,in the medium and high-speed domain,this thesis proposes to use a smooth piecewise exponential function to replace the switching function in the traditional sliding mode observer.The system chattering is effectively weakened by combining the adaptive algorithm with the improved sliding mode observer.The normalization process is added in the phase-locking link to obtain higher-precision motor rotor position and speed estimation information.By establishing the corresponding simulation model,it is proved that the improved sliding mode observer proposed in this thesis can effectively reduce chattering compared with the traditional sliding mode observer.Secondly,in the low-speed domain,this thesis adopts the improved highfrequency square wave voltage injection method to replace the traditional pulse vibration injection method,which reduces the influence of narrowing of the system bandwidth when acquiring the fundamental frequency current and high-frequency current signals.The control method realizes the separation of fundamental frequency signal and high frequency signal without filter.And the more accurate rotor position and speed information can be obtained through the Luenberger observer.The position sensorless control algorithm in the full-speed domain is obtained by combining the high-frequency square wave injection method in the low-speed domain and the improved sliding mode observer in the medium-high-speed domain with a weighting factor.The system simulation model is built by the simulation software platform to verify the validity of the algorithm.Finally,an experimental platform for the position sensorless control system of permanent magnet synchronous motor is built with TMS320F28335 as the core.The platform is to verify the actual effect of the positionless composite control strategy of permanent magnet synchronous motor proposed in this thesis.The experimental results show that the rotor position and speed can be improved in the full speed range estimating ability.