Research On PMSM Sensorless Control System Based On Improved Sliding Mode Observer

Permanent magnet synchronous motor(PMSM)sensorless control system using sliding mode algorithm has many advantages such as simple structure,high efficiency,good robustness,etc.,and has gradually expanded its market share in the industrial control field.However,the PMSM control system based on the traditional sliding mode algorithm(TSMO)has a large chatter error,which cannot meet the requirements of high precision control in the fields of machine tools,robots,and pure electric vehicles.Therefore,it is of great engineering significance to study the improved sliding mode observer to improve the estimation accuracy while effectively suppressing chatter.Based on the mathematical model of PMSM,this paper adopting the SVPWM vector control scheme and i_d=0 control strategy,establishes the construction of TSMO sensorless control system and improves it.Aiming at the problems of high-frequency chattering in TSMO and large errors in the rotor position estimation of motors,the method of adding a secondary back-EMF observer was used to introduce the back-EMF observation signal into the sliding mode algorithm as feedback to form the back-EMF-sliding mode(BEO-SMO)two-stage observation equation to obtain a smoother and more accurate back-EMF signal,thereby achieving high-precision tracking of the rotor position.The convergence is proved by Lyapunov stability theory.Theoretical analysis shows that the addition of a secondary observer has a Kalman filtering effect,which is equivalent to secondary filtering of the back-EMF signal,while avoiding the phase shift problem and greatly suppressing chattering.To enhance the robustness of the system.In addition,the system chattering can be further reduced by changing the switching function and the PLL curcuit.TSMO and BEO-SMO simulation models are established in MATLAB to verify the feasibility and effectiveness of the algorithm proposed in this paper.Compared with the results of TSMO simulation analysis,the control system after adding back-EMF observers can effectively suppress chattering,improve the estimation accuracy of the rotor position,and have better dynamic response characteristics.Finally,an experimental platform of PMSM sensorless control system was established with TMS320F28335 and PS21865 as the core components.The proposed PMSM sensorless control system based on BEO-SMO observer was verified.The experimental results show that the control system can maintain good operating characteristics.The estimation accuracy of the sensorless algorithm meets the requirements.