Research On Sensorless Control Of Surface-Mounted Permanent Magnet Synchronous Motor

In recent years,permanent magnet synchronous motor is widely used in fields of numerical control machine,electric vehicle and rail transit traction drive,because of it owns such qualities as simple structure,reliable operation,high power density,high efficiency,flexible design of shape and size,and well control performance.As well known,rotor position and rotate speed information are usually provided by mechanical position sensor,which is necessary in permanent magnet synchronous motor control system.But problems as reliability decline,power density decrease,cost increase,application environment limitation,etc,come with the utilization of mechanical position sensor.Thus,the method of sensorless control which solve problems above become a research focus in electric field.Take an overview of research on sensorless control worldwide,we can find most of them are based on the mathematical model of motor and only applicable when motor's rotate speed fast enough.In low speed situation to realize sensorless control,high frequency signal injection is a applicable and well-performed method.It make use of the structure or saturation saliency of permanent magnet synchronous motor,through processing the response of injected signal to determine rotor position information,and send it to control system as feedback.This article is about to research on sensorless control of motor under low rotate speed situation,basing on high frequency signal injection method.The kind of motor this article research on is non-salient pole machine,so the well researched rotating high frequency voltage injection method which base on the structure saliency of salient pole machine to work,is unable to be used.Only fluctuating high frequency signal injection,which inject signal into machine's direct axes to create saturation thus get saliency,is qualified to realize speed estimation.This article firstly do a thorough theory research about fluctuating high frequency voltage and current signal injection,and then by means of MATLAB/Simulink.the simulation realization of sensorless control basing on signal injection is done.Voltage injection scheme extracted response current through band-pass filter,to remove the position estimation error in the modulation signal,the PI regulator was uesd,whose output is estimated speed.As for the current injection method,by changing signal injection position,it has improved the stability compared to the voltage injection scheme,and by adopting the proportional resonant controller,also has improved the performance of motion control system.The simulation results shows that the proposed methods perform well in estimation of rotor rotate speed,and also shows well performance in rotor steady and dynamic state.