Position Estimation And Control Of Permanent Magnet Synchronous Motor Based On Composite Observer

A back-EMF observer is designed for the sensorless control technology of permanent magnet synchronous motors.In the presence of current measurement errors,a design method of composite observer is proposed.By adjusting the parameters of the observer in the closed-loop system,the effectiveness of the designed observer is guaranteed.The robustness of the composite observer in the presence of measurement errors is analyzed,and a fuzzy PI control is built in the speed loop PI regulator based on the composite observer.The specific research work is as follows:(1)In order to obtain the position signal and speed signal of the motor,a back-EMF observer is designed.The motor reference model is constructed according to the actual mathematical model of the motor,and the back EMF characteristics are excited by the error signal obtained.A nonlinear observer is designed to estimate the constant scalar related to the frequency of the back EMF,and an auxiliary filter is constructed to reconstruct the back EMF.The observer design method has a simple structure and is easy to analyze.The back-EMF observation value only involves the calculation of an unknown frequency of a parameter,which greatly weakens the chattering,reduces the harmonic content,and further improves the back-EMF observation accuracy.(2)Aiming at the current measurement error value of the current sampling process,a design method of composite observer is proposed.The reference model is introduced to obtain the error signal including the characteristics of the back EMF,and it is decomposed into the standard error signal and the measurement error value.The improved auxiliary filter is constructed to express the standard error signal as a parameter form related to the auxiliary variable,so as to realize the separation of the standard error signal and the measurement error.The back-EMF observer is designed according to the estimated value of the standard error signal.The robustness of the composite observer is ensured by adjusting the observer parameters.(3)First,the robustness of the composite observer under the measurement error environment is verified,which can ensure the boundedness of the position estimation and coordinate transformation matrix errors,and then convert the problem into a closed-loop vector control system design problem.The fuzzy PI controller is constructed based on the compound observer.The simulation results show that the fuzzy PI control realizes parameter self-tuning,and has higher stability and superior dynamic performance.