Research On Torque Ripple Suppression Of Permanent Magnet Synchronous Motor System

Permanent magnet synchronous motor(PMSM)is more and more widely used as the main actuator in high precision servo system.But the traditional motor control system of permanent magnet synchronous motor in cogging torque and back EMF harmonics and the inverter power devices lead to problems such as torque ripple and electromagnetic noise,affect the control performance of the control system.This paper analyzes the factor that cause control system of permanent magnet synchronous motor torque ripple,through the research of motor structure design optimization and torque ripple suppression control method and dead time compensation control strategy,the purpose of reducing torque ripple is achieved.The main contents of this paper are as follows:In view of the domestic and foreign development situation of permanent magnet synchronous motor servo control system of torque ripple suppression techniques are summarized,analysis of various characteristics of reducing torque ripple of the motor structure optimization method and torque ripple suppression control strategy,summarized all kinds of optimization methods and the advantages and disadvantages of control strategy.Through theoretical analysis on the factors of permanent magnet synchronous motor torque fluctuation,the structure such as permanent magnet parameters,magnetic bridge,pole slot combination that affect the torque ripple are discussed.,the effects of back EMF,gap density,harmonic and cogging torque on the output torque of motor are studied.By using the finite element calculation of eccentricity of rotor,permanent magnet design parameters were optimized to reduce the back EMF and torque harmonic,and put forward an optimum design method of an auxiliary magnetic bridge optimization motor,further optimize the magnetic circuit to achieve further suppression of torque ripple.The current distortion caused by dead voltage deviation resulting in increased motor torque ripple.According to analyze the effect of dead time error on phase voltage and current,the laws of output voltage error and the power device turn-on and turn off time and voltage drop under fixed dead time disturbance voltage regulation are obtained.This paper presents a simple and direct compensation technique to solve this problem in a three-phase VSI.Thus,the current harmonic and torque ripple in the running state of the motor are suppressed,and the system modeling and Simulation of the method are also carried out.A vector voltage model of dead time disturbance voltage in stationary and rotating coordinate system is established,to deal with the change of switching time and the change of voltage drops on power devices.A dead time voltage observer is used to identify the dead time characteristics of the inverter in order to compensate the dead time effect precisely based on the relatively stable trend of the amplitude of the disturbance voltage vector.In order to improve the robustness of the current loop,the paper proposes a control strategy based on the combination of model reference adaptive control strategy(MRAC)and voltage of current loop disturbance observer.And simulation verification is also carried outFinally,the torque ripple suppression controller of permanent magnet synchronous motor is developed based on DSP control chip,and the test platform is built with the prototype.The flux linkage and the d-q axis inductance are measured,and the dead time observer compensation control strategy is tested.The experiment based on the combination of dead observer and MRAC compensation is carried out.The effect of disturbance compensation is verified by dead zone observer and model reference adaptive.