Position Sensorless Control Of PMSM Based On Recursive Observer

Because of its low loss,high power factor,high efficiency and other advantages,permanent magnet synchronous motors have been widely used in all walks of life.The quality of their control performance directly affects people's production and life.Because mechanical sensors have high installation and maintenance costs,limited application scenarios,and low reliability,in order to broaden the application field of permanent magnet synchronous motors,the position sensorless control of permanent magnet synchronous motors was studied.The specific contents are as follows:First,in order to obtain accurate rotor position and speed,a recursive observer was designed.The back-EMF frequency was estimated first,and then the continuous smooth back-EMF was calculated by the reverse recursion method,and the rotor position and speed are obtained through the relationship of the arc tangent function,thus effectively avoiding the phenomenon of sliding mode chatter.The simulation shows that the designed observer has the characteristics of high precision,and the phase delay was smaller and the tracking performance was better.Secondly,the sliding mode is very robust to disturbances caused by uncertain factors,and a composite observer switching estimation strategy was proposed.By designing a fractional-order adaptive terminal sliding mode observer,the continuous smooth back EMF was estimated,and the rotor position and speed were obtained through the phase-locked loop.Finally,a suitable switching strategy was obtained to achieve smooth switching between the two observers,and a composite observer based on the recursive observer and the fractional-order adaptive terminal sliding mode observer was constructed,which weakens the phenomenon of sliding mode chattering.Through simulation,the superiority of the composite observer was verified.Finally,in order to improve the performance and accuracy of the sensorless control,a speed controller based on disturbance observation was designed.The global sliding mode factor was introduced on the non-singular terminal sliding mode surface,the sign function was replaced with a saturation function,a new approach law was designed and an interference observer was constructed to estimate regular disturbances in the motor system,so chattering was effectively reduced,the robustness of the system was improved.Through simulation verification,the designed controller can cooperate with the composite observer,which can realize the sensorless control of the motor,and at the same time ensured the robustness and estimation accuracy of the observer.