Research On Position Sensorless PMSM Based On Sliding Mode Observer

When adjusting the speed of a motor,the speed control of a permanent magnet synchronous motor requires the use of rotor position information,but the installation of mechanical sensors will have many effects on the control system,such as being susceptible to noise,increasing the system volume,weight,and increasing the drive.The complexity of the system reduces the reliability of the system.In order to improve system performance,sensorless control technology is generally used to collect the position signal of the motor rotor.This paper comprehensively and in-depth discusses the research status of the sensorless control algorithm for permanent magnet synchronous motors,selects the sliding mode observer method for research,and based on the existing algorithms,makes related improvements and proposes application saturation.The functional segmented function replaces the original switching function,which improves the accuracy of the observation position.Finally,the research is carried out based on the demand of the pumping unit for the frequency conversion speed regulation function.The content of this article is as follows:Firstly,the research significance of this article is explained,and the development trend,classification and research status of permanent magnet synchronous motors are analyzed.Permanent magnet synchronous motors have simple body structure,small size,high energy density,light weight,high power factor,high reliability,and maintenance.Convenience and other advantages are very suitable for application in oil fields.Compared with the various control methods and advantages and disadvantages of the position sensorless method of the permanent magnet synchronous motor,the sliding mode observer method has the advantages of strong robustness,insensitivity to external environment interference and parameter changes,and finally the sliding mode observer method is selected as research content.Secondly,starting from the main modules and control principles of the permanent magnet synchronous motor control system,the conversion relationship between the three coordinate systems and the motor model are derived in detail.The advantages and disadvantages of several commonly used vector control strategies are discussed respectively.Through comparative analysis,starting with PWM,the principle of voltage space vector pulse width modulation(SVPWM)is deeply studied,and SVPWM technology is used as the control strategy in this paper.Thirdly,the theory of sliding mode variable structure control is studied in depth,and the sliding mode observer is analyzed and applied to sensorless control.Aiming at the problem ofhigh-frequency chattering of sliding mode observer,an improved saturation function type piecewise function is selected to replace the traditional switching function,and a phase-locked loop is added to eliminate the effect of chattering.Through MATLAB simulation,the simulation model of the sensorless control system of sliding mode observer under the vector control of permanent magnet synchronous motor is established.Establish a comparison between the traditional sliding mode observer and the improved sliding mode observer model,and test whether the response can be fast when the load changes.By comparing the results,it is proved that the improved control system is indeed superior to the traditional algorithm.Finally,the speed regulation system of the pumping unit is briefly introduced,and the position sensorless control of the sliding mode observer is applied to the variable frequency speed regulation system of the pumping unit.Through performance testing,the improved algorithm can indeed estimate rotor position information and complete the entire control process,and analyzes the development prospects and market value of this strategy from the aspects of power saving and cost saving.