Research On Sensorless Control Strategy For PMSM And Its Improved Sliding Mode Observer

Permanent Magnet Synchronous Motor(PMSM)is widely used in military,aerospace,power transmission systems,and other fields due to its superior structural characteristics,working reliability,and operating efficiency compared to DC and asynchronous motors.This article conducts research on the working principle of PMSM,vector control model,traditional sliding mode observer design,position sensorless control strategy of PMSM based on improved sliding mode observer,and digital control system implementation.The main work and achievements are as follows:1.Summarized the research background,significance,technical research status,and development trend of PMSM,with a focus on analyzing the traditional vector control methods of PMSM.On the basis of analyzing the position sensorless control of PMSM,mathematical models under two coordinate systems of PMSM were established,and conventional control methods were studied.The model was built using MATLAB for vector control simulation verification.2.A traditional sliding mode observer for PMSM was designed.Based on the analysis of the development history of sliding mode observers and the principle of sliding mode variable structure control,a sliding mode observer for PMSM was designed in two-phase stationary and two-phase synchronous rotating coordinate systems.3.The characteristics of sliding mode observers designed in different coordinate systems were analyzed,and a simulation model of PMSM sliding mode observers in different coordinate systems was built using MATLAB,providing the basis for selecting two-phase synchronous rotating coordinate systems.Based on the analysis of the pulse voltage method,a vector application method based on the bisection idea is proposed to address the small amplitude "jitter" phenomenon in the estimated rotor position and speed,which improves the accuracy of initial angle identification.At the same time,improvements have been made in four aspects: switch function,low-pass filter,speed extraction,and Kalman filtering,which have been verified through MATLAB simulation to further effectively suppress "jitter".4.A control system was designed based on DSP+FPGA,introducing hardware design principles,software workflow diagrams,etc.The upper computer interaction system was designed based on DMT80480T070＿06W.The communication between the upper computer and the control board was elaborated in detail.The experimental results verify the correctness of the improved sliding mode observer and initial angle identification theory designed in this dissertation.