Research On Sensorless Control Of PMSM At Full Speed Range

Compared with other types of motors,Permanent Magnet Synchronous Motor has a smaller space occupancy,a larger power density and a higher efficiency,which is widely used in all aspects of production and life.However,the traditional mechanical sensors are often difficult to maintain in the ac drive system of PMSM,which reduces the stability and reliability of ac drive control.For the problem of low reliability of mechanical sensors,this paper adopts sliding-mode observer in the middle and high speed range and pulse-vibration high-frequency voltage injection method in the low speed range to realize the sensorless control in the full speed range in PMSM control.In order to ameliorate the estimation accuracy of rotor position and velocity of the permanent magnet synchronous motor by traditional sliding mode observer,an s-type control function based on adaptive sliding mode boundary layer is designed,and an improved sliding mode observer is constructed by PLL system.Firstly,a motor model with PMSM as the research object is established and the current sliding surface is constructed.Secondly,by using the design idea of variable sliding mode boundary layer and considering the characteristics of the boundary layer,the s-type control function with the speed adaptive adjustment to the boundary layer thickness is used to replace the traditional switching function,which is beneficial to suppress the chattering of the system and improve the observation performance.Then,in view of the weak tracking performance in the dynamic phase when PLL is used to estimate the rotor position and speed signal,and the phenomenon of speed jump when the boundary layer changes,a signal suppressor is designed to reduce the dynamic error and improve the estimation accuracy of the system.Finally,the simulation analysis by Matlab/Simulink proves that this method is feasible and achieves high estimation accuracy.In order to establish the estimation algorithm in the low-speed range,the basic principle of the pulsed high-frequency voltage injection method is first explained.Secondly,the estimation process of the algorithm is analyzed in detail.Finally,build a model on the Matlab/Simulink platform and perform simulation analysis.A composite control system based on sigmoid function is designed to ensure that the high and low speed estimation algorithm can switch control smoothly.Firstly,a reasonable compound control interval is designed according to the parameters of PMSM.Secondly,Sigmoid function is used to calculate the weight value to further reduce the rotation speed fluctuation in the switching process of the two estimation algorithms,so as to ensure the smooth transition of the composite control interval system.Finally,Matlab/Simulink simulation is used to verify the effectiveness of the method.