Research On Position Sensorless Control Of Permanent Magnet Synchronous Motor

Permanent Magnet Synchronous Motor(PMSM)has attracted more and more attention from academia and industrial applications due to its high power density,fast dynamic response and large constant power speed range.In traditional highperformance control,the speed and position loops require real-time and accurate position information.The position information is often obtained by installing encoders on the crankshaft,but mechanical position sensors will increase the cost and reduce the reliability of the system.And sometimes the actual working environment is not suitable for installing the encoder,so the PMSM high-performance drive based on the position sensor has become a research hotspot.When the PMSM is in low-speed and zero-speed operation,high frequency(HF)injection is an effective method to obtain motor position information,but the additional HF signal injected into the motor will cause the motor to vibrate and generate HF noise,which will affect it in some cases User experience.Therefore,this thesis studies the PMSM position sensorless drive control technology based on random HF signal injection,and verifies the studied position sensorless control strategy through simulation and experiment.The main research contents of this thesis are as follows:First,the research status of PMSM sensorless control at home and abroad is reviewed.The basic structure,mathematical model,and the principle of three commonly used coordinate transformations of the PMSM rotor magnetic circuit are studied,and then the principle and implementation of the Space Vector Pulse Width Modulation(SVPWM)technology are introduced in detail,and analyzed and determined the Field Oriented Control(FOC)motor control strategy used in this thesis and a simulation model were built to verify the relevant simulations.Secondly,in order to obtain motor speed and position information under low or even zero speed conditions,a fixed HF injection method is used.According to the difference of the injected signal,the expressions of the HF response current excited by the two HF injection signals are analyzed and deduced,and the filter and position observer are designed to realize the estimation of the rotor position.Finally,two HF signal injection methods are built.The simulation verifies the effectiveness of the HF signal injection method.Then,based on the above analysis results,this thesis studies the causes of HF noise generated by the HF signal injection method.When a fixed frequency is used to inject into the motor,the power spectral density(PSD)of the response current is concentrated on the fixed frequency.Therefore,the motor will emit a sharp and piercing noise.This thesis adopts the random HF signal injection method to reduce the peak value of the current PSD by randomly changing the frequency of the injected signal,and introduces the injection method and selection conditions of the random signal.Finally,a simulation model of the random HF signal injection method was built to verify the effectiveness of the method.Finally,experiments were carried out by designing and building an experimental platform.The results show that the random HF signal injection method can effectively estimate the rotor position of the PMSM at low speed and zero speed,and realize the high-performance closed-loop drive control of PMSM without position sensor at low speed,Verified the feasibility and effectiveness of the algorithm designed in this thesis.