Study On Current Loop Harmonic Suppression Technology Of Permanent Magnet Synchronous Motor

In the traditional AC speed control system of Permanent Magnet Synchronous Motor,there is a lot of high order harmonic in the motor stator current due to the distortion ofair-gap magnetic field and the nonlinear characteristics of the inverter. These harmonicwill cause the motor electromagnetic torque ripple, which restricts the applications ofPMSM in high speed and high precision areas. To improve the motor dynamicperformance and extent the use of the PMSM, it is very significant and meaningful toanalyze the causes of harmonic and study the methods to restrain the harmonic.For the reason of analyzing the causes and characteristics of harmonics, thetime-based harmonics are chosen as the key object in our research firstly. Then, asignificant conclusion is derived that they are mainly the fifth and seventh harmonic of thefundamental wave. In order to suppress these harmonics mentioned before, two kinds ofnovel compensation algorithm are proposed, and they are based on coordinatetransformation and adaptive notch filter respectively. In the former proposed method, theharmonic current are extracted by the fifth and seventh rotating coordinate separately, andthe corresponding harmonic current controllers are constructed to suppress harmonics. Inthe later proposed method, the adaptive notch filters extract the sixth harmonic in d/qsynchronous rotating coordinate shaft. Taking full advantage of the original d, qcontrollers, harmonic current in three-phase current can be well suppressed. Both of themethods improve the quality of motor three-phase current and d/q current, and suppressthe torque ripple effectively.In order to verify the effectiveness of the two presented methods, simulation and experiments are conducted on MATALB/Simulink and a STM32based Servo Driver TestPlatform respectively. Both of the methods improve the quality of motor three-phasecurrent and d/q current, and suppress the torque ripple effectively.