| In driving equipments,the angular position of Permanent Magnet Synchronous Motor must be accurate and reliable,which is related to the performance of the control system.Under harsh working conditions,the conventional motor position sensor may not be able to accurately obtain the rotor position information,resulting in position deviations in the closed-loop control of the system,and the control accuracy is greatly reduced.Therefore,in order to increase the reliability of the control system,this dissertation proposes a concept of sensorless observer in a full speed range to replace the traditional position sensor.In different speed regions,the method of pulse high frequency voltage injection and sliding mode observer in synchronous rotating coordinate system are switched to realize the position estimation of each speed region.By detecting electrical signals containing position information,the observer estimates the rotor position and completes the closed-loop control of the motor in the full speed range.In the high-speed area,the control algorithm compensates the lag angle,detects the out-of-step condition of the estimated speed,and optimizes the accuracy of the positionless control system.First,this article comprehensively investigates the current research status of positionless sensor algorithms,and summarizes the existing shortcomings of positionless observers: firstly,how to complete the closed-loop control of the motor without position sensor in the full speed domain;second,in the high speed area,how to optimize the control accuracy of the motor;third,in the medium and high speed area,when the load is suddenly applied,the real-time tracking performance of the traditional sliding mode observer is poor.Taking the above three issues as the starting point,this article mainly does the following research:In this dissertation,a new observer and a weighted transition scheme with asynchronous speed and position are proposed to complete the positionless control of the motor in the full speed range.In the low-speed region,the observer is estimated based on the pulsed high-frequency voltage injection method;in the medium-high-speed region,the sliding mode is used for synchronous rotating coordinate system observation.In the transition zone between the two sections,a transition scheme in which the angular position and the rotational speed are not synchronized is used,and two algorithms are flexibly switched to complete the rotor position estimation in the full speed range.In order to further improve the controlled accuracy of the motor in the high-speed region,this dissertation proposes a step-out detection strategy and a lag angle compensation strategy to ensure the load capacity and reliability of the motor in the high-speed region.In the medium and high speed region,this dissertation comparatively analyzes the tracking effect and estimated deviation of two sliding mode observers under sudden load conditions,and selects the sliding mode observers in the synchronous rotating coordinate system to complete the rotor position estimation.Secondly,this dissertation carries out theoretical derivation and mathematical modeling,verifies the feasibility of the theoretical basis from a theoretical level,and makes theoretical preparations for building experimental projects.This dissertation uses Matlab/Simulink software to build a simulation model for simulation analysis.The results verify: the reliability of the operation of the motorless position control system at full speed,the smoothness of the estimated speed of the transition of the weighted switching scheme with asynchronous speed and position,and good tracking performances when the new sliding mode observer in the medium and high speed region is suddenly loaded.Finally,set up a hardware experimental platform for positionless sensor control system,and design software algorithms for positionless control systems.From the practical application level,the correctness and practicability of the conclusions obtained in this dissertation are verified. |
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