Research On The Control System Of Permanent Magnet Synchronous Motor Without Position Sensor

Permanent magnet synchronous motor has high efficiency,low loss,high power and other characteristics,is one of the commonly used automotive motor,permanent magnet synchronous motor need to use position sensors to obtain rotor position information for control.In order to further improve the control reliability and reduce the control components,it is of good application to study the position sensorless control system in automotive permanent magnet synchronous motor.The traditional control strategy of permanent magnet synchronous motor without position sensor generally takes zero-low speed control and medium-high speed control as independent units,for the stable control of automotive permanent magnet synchronous motor in the full speed domain,it is necessary to study the segmented control of different speed domains and constitute a composite control system.This paper analyzes the control system of permanent magnet synchronous motor without position sensor,specifies the control strategy based on magnetic field orientation,adopts pulsation high frequency injection method for rotor position detection at zero and low speed,adopts sliding mode observer for rotor position detection at medium and high speed,and analyzes the control algorithm switching strategy.Analysis of the convex polarity of permanent magnet synchronous motors during motor start-up to achieve zero-voltage inductorless rotor initial position detection.The low-speed control system is optimized for the influence of nonlinear factors in the inverter on the rotor position observation using a second-order generalized integrator based on the pulsating high-frequency voltage injection method.The simulation verifies that the improved pulse oscillation high-frequency voltage injection method can effectively suppress harmonic interference and improve the estimation accuracy.Sliding mode observer based position sensor free control in a medium and high speed control system.To address the problems of system jitter and lag in the observed position information of the inverse tangent function of the traditional sliding mode observer,the superhelix algorithm is introduced to build a superhelix second-order sliding mode observer,and the sigmoid saturation function is chosen to replace the sign function,and the fuzzy control is designed to optimize the sliding mode gain,which effectively reduces the jitter problem of the sliding mode observer.At the same time,the normalized phase-locked loop is designed to replace the inverse tangent function for rotor position estimation in response to the observed position information lag.The simulation verifies that the improved sliding mode observer can effectively reduce the system jitter and improve the rotor position detection accuracy.A weighted switching method based on the improved sigmoid saturation function is designed for switching from zero low speed to medium high speed without position sensor control algorithm,which effectively improves the accuracy of switching interval estimation and smoothness of switching.To weaken the interference of the injected voltage signal to the sensorless algorithm in the middle and high speed stages,an attenuation function is designed to gradually reduce the injected voltage to zero to ensure a smooth switching process.The feasibility and effectiveness of the improved weighted switching method are verified by simulation.Based on the system simulation verification of the full-speed domain composite control strategy,the permanent magnet synchronous motor experimental platform is built,hardware and software system debugging is performed,and the feasibility and effectiveness of the control strategy is experimentally verified.