Harmonic Suppression Technology Of Permanent Magnet Synchronous Motor Based On New Generalized Integral Observer

In recent years,permanent magnet synchronous motors(PMSM)with many advantages such as small size and high efficiency have been gradually applied in various industries.However,due to the nonlinear characteristics of the inverter and the harmonics of the space flux linkage,harmonic components are generated in the motor drive system.Among them,current harmonics will cause torque ripple of the motor;back-EMF harmonics will cause errors in the rotor position observed in the sensorless control system.In order to suppress the harmonic components in the drive system and improve the control accuracy of the system.In this paper,based on the traditional second-order generalized integrator,two new generalized integrators are proposed and applied to the harmonic suppression strategy of PMSM drive system.First,under ideal conditions,the ideal voltage equation is derived based on the PMSM equivalent structure diagram.Furthermore,under non-ideal conditions,the PMSM voltage equations with 5th and 7th harmonics are derived from the analysis of the nonlinear characteristics of the inverter and the flux linkage harmonics.Secondly,aiming at the current harmonic problem in the control system with position sensor.The traditional method is to use harmonic compensation strategies to suppress current harmonics.However,in the harmonic observation process of this strategy,the observer has the problems of wide pass band and difficult parameter setting.This paper proposes a third-order generalized integrator for current harmonic observation.Through detailed theoretical derivation,this paper demonstrates that the new integrator has the characteristics of narrow bandwidth,high attenuation and easy adjustment compared with the traditional second-order generalized integrator.The simulation verifies that the harmonic compensation method based on the new integral observer has a higher harmonic attenuation rate than the traditional method,which effectively improves the observation accuracy of current harmonics.The current waveform in the drive system is obviously sinusoidal,and the torque ripple Got weakened.Then,the problem of back-EMF harmonics in the sensorless control system is addressed.This paper proposes a fourth-order generalized integrator for back-EMF harmonic suppression.The new integrator is combined with a frequency-locked loop that can track the rotor frequency without difference,and is suitable for a position sensorless control system with low rotor frequency accuracy.Theoretical analysis proves that the new integrator can highly suppress the harmonic components of the back electromotive force.Experiments show that the position observer based on the integrator can basically filter out the 5th and 7th back-EMF harmonics,the back-EMF waveform is closer to the ideal sine,and the accuracy of the rotor position observed is significantly improved.Finally,a comprehensive experiment and comparative analysis of the results were carried out on the PMSM experimental platform.The comprehensive experimental results show that the harmonic suppression technology of the permanent magnet synchronous motor based on the new generalized integral observer effectively reduces the harmonic components in the drive system and improves the control accuracy of the drive system.