Research On Sensorless Control Of Surface Permanent Magnet Synchronous Motor In Low Speed

Permanent magnet synchronous motor(PMSM)is widely used in various industrial fields with its features of high efficiency,energy saving and good speed regulating performance.In PMSM control system,the direct way to guarantee closed-loop control to PMSM is install a velocity/position sensor on the rotor shaft.However,high cost,low reliability,more space needed and hardly to change or maintenance prompt people turn to the sensorless control technology research.Due to the salient pole effect is small especially for the surface PMSM,traditional control method always has a bad efficiency.In view of this kind of situation,this paper adopt low frequency signal injection method which does not rely on motor's parameters and salient pole effect,could achieve a good control result to SPMSM in a low speed.Firstly,this paper introduced the structure characteristic,mathematic models and coordinate transformation of PMSM.Then analyzed the Space Vector Pulse Width Modulation(SVPWM)technology in vector control,according to this theory,set up simulate modules including Clarke transform,Park transform and SVPWM,established integrated model of vector control system with(28)0di method and realized the simulation.Secondly,analyzed the principle of low frequency signal injection method,built SPMSM sensorless control system model which based on low frequency signal injection method in MATLAB/SIMULINK,utilized speed estimate module instead of speed sensor to estimate motor speed.Chose suitable injection signal after analyzed,then had a system simulation under the condition of speed and load changed.Finally,adopt TMS320F28335 DSP,PS21867 IPM,voltage and current sampling circuit,drive circuit,filter circuit,buffer circuit and a PMSM which rated power is 1.8kW to established experimental platform.Programmed in CCS6.0 including main routine,interrupt subroutines and software arithmetic,and gave the routine flow chart.