Research On Harmonic Suppression Strategy Of Permanent Magnet Synchronous Motor Based On Harmonic Extractor

Permanent Magnet Synchronous Motor(PMSM)has the characteristics of small size,light weight,high efficiency and power density,and simple control structure.With the gradual improvement of the performance of permanent magnet materials such as neodymium iron boron,control theory and high performance With the increasing development of processors,they are widely used in fields such as CNC machine tools,electric power drives,and aerospace.However,PMSM is affected by the non-linear factors of the inverter during operation and the lack of structural design of the motor itself,which will cause the stator current to produce harmonics during the operation of the motor,thereby distorting the stator current of the motor,causing the motor to produce torque ripple and Additional loss.In this thesis,aiming at the harmonic problem of PMSM stator current,a PMSM harmonic suppression strategy based on harmonic extractor is proposed.The research work can be summarized as follows:First of all,the mechanism of the harmonic generation of the motor stator current is analyzed,and the control strategy to suppress the motor harmonic current is studied from the control point of view.In the harmonic component extraction link of the traditional harmonic current detection method,the PI controller cannot track the harmonic AC quantity without static error,which leads to the low accuracy of this harmonic detection method.Secondly,in response to the above problems,this paper proposes an improved harmonic detection structure based on positive and negative sequence fundamental wave extractors.This structure is constructed based on the principle of amplitude integral signal and frequency selection characteristics.It can track AC signal volume without static error.According to the band-pass filtering characteristics of the fundamental wave extractor,a specific order harmonic extractor is obtained by setting the frequency to extract the 5th negative sequence harmonics and the 7th positive sequence harmonics respectively,and extract the 5th negative sequence The harmonics and the 7th positive sequence harmonics are compensated to the output reference voltage as the compensation amount,which reduces the 5th and 7th harmonic content in the stator winding current.This strategy reduces the cumbersome calculations caused by the coordinate transformation of the traditional algorithm.The control performance of the system has been improved.Then,with three-phase PMSM as the research object,a PMSM system simulation model with dead time is built based on the Matlab/Simulink platform.Finally,in order to prove that the harmonic suppression strategy of the PMSM vector control system based on the harmonic extractor is feasible,the simulation research under different load torques was carried out on the Matlab/Simulink platform,and the harmonic detection proposed in this paper was added separately.The simulation results before and after the structure were compared.The simulation results show that after adding the PMSM harmonic suppression strategy based on the harmonic extractor proposed in this paper,the harmonic content of the phase current in the stator winding is reduced,and the sine of the phase current waveform has been significantly improved.The harmonic suppression strategy can achieve the purpose of harmonic suppression.