Research On Sensorless Control System Of PMSM For Inverter Air Conditioning Compressor

With the growth of economy and the lack of energy,the inverter air conditioner has more advantages in energy saving and environmental protection than traditional fixed frequency air conditioner,so that the technology of air conditioning is developing towards frequency conversion,antibacterial,silent and intelligent.Comparison of induction motor,permanent magnet synchronous motor(PMSM)has high power factor,high efficiency and easy control etc,so it is widely used in the field of household air conditioners and commercial air conditioners,which has become a hot topic in the new generation of universitity and enterprise’s research.In the procedure of PMSM vector control,the motor rotor pole position information is the key to detection.The mechanical sensor is installed on the motor shaft,which is susceptible to high temperature/pressure and bad environment.Therefore,it is necessary to adopt the sensorless control algorithm to obtain the rotor pole position information.Firstly,this thesis fouces on the position sensorless vector control system of PMSM for air conditioning compressor.Based on the analysis of PMSM’s structure,this thesis builds the PMSM’s mathematic model according to its characteristics.This thesis also does theoretical research on the two closed loop vector control system in great depth and builds PMSM’s vector control simulation model on the basis of the vector control’s principle in Matlab/Simulink.Secondly,this thesis deeply improves and extends traditional sliding mode observer(SMO).Variation gain,Sigmoid function and back-EMF adaptive filter are used to resolve high frequency chattering issue for SMO,and PLL theory is uesd to estimate rotor pole position information.At the same tine,the stator resistance online identification is joined in SMO to improve estimation accuracy of rotor’s position and system robustness.Because of the fluctuation of the speed caused by the periodic change of the compressor load,the PDFF speed feed-forward regulator is selected instead of the PI speed loop.In addition,apply for the method of pre-position open-loop starting to resolve the problem of starting for PMSM sensorless control.Finally,the Matlab/Simulink simulation platform is built to analyze the dynamic/static performance and robust performance of the sensorless vector control system of PMSM based on observers.