Research On Current Harmonics Suppression Strategy Of Permanent Magnet Synchronous Motor

Permanent magnet synchronous motors(PMSMs)have been widely used in the fields of industrial,aerospace and household appliances because of its high operating efficiency and high torque output ratio.However,due to the nonlinearity of the inverter and the design and process deviation of the motor,the back-EMF waveform is distorted and the harmonic current is introduced.The current harmonic causes the increase of motor loss and torque ripple,which makes the control effect of the system worse,which greatly affects the application of PMSM in the high performance situation.Therefore,it is of great significance to analyze the source of current harmonics,and to study the current harmonic suppression strategies to improve the control performance of the system.First of all,the voltage and current harmonics generated by the nonlinearity of the inverter are analyzed and studied.The PMSM harmonic mathematical model,which considers the voltage current distortion and the non sinusoidal back EMF,is established,which provides the necessary theoretical support for the next step of the effective current harmonic suppression algorithm.Aiming at the 5th and 7th current harmonics with high content in permanent magnet synchronous motor system,the harmonic suppression strategy of specific frequency current based on rotating PI controller is studied.The harmonic current loop is constructed to suppress the current harmonic component and improve the control performance of the system.On this basis,a complex PI controller which is extended to the whole complex domain is proposed,which can be used to suppress the current harmonics with the characteristics of the AC signal without static difference following.Studying the implementation method of the plural PI controller,and analyze and discuss the influence of its parameters on the control system.In order to solve the problems of complex calculation and difficult parameter setting of PI controller and improve the motor current waveform,this paper proposes a current harmonic suppression strategy based on repeated controller.The non-linear characteristics of the inverter and the magnetic field distortion of the air gap are regarded as disturbance signals.The repetitive controller can eliminate the harmonics,suppress the torque ripple,and improve the control performance by completely suppressing the periodic disturbance.The mathematical relationship between the repetitive control and the resonance control is deduced,and the idea of using the resonance controller to increase the bandwidth is used to improve the repetitive controller internal model,and the sensitivity of the repetitive controller to frequency fluctuation changes is improved.By improving the delay time of therepetitive controller,the data storage space demand can be reduced,and a fractional order repetitive controller is designed to solve the problem of decimal precision based on the Lagrange interpolation method,which can make up for the shortcomings of the repetitive controller.Finally,the hardware experiment platform of PMSM based on DSP control chip TMS320F28335 is designed,and the experimental verification of current harmonic suppression strategy is carried out by software programming.The experimental results verify the effectiveness and rationality of suppression strategies proposed in this paper.