Research On Current Harmonic Suppressions Strategy Of High Speed Permanent Magnet Synchronous Motor Based On Super-twisting Sliding Mode Control

Compared to ordinary permanent magnet synchronous motors,High Speed Permanent Magnet Synchronous Motor has advantages such as small size,high power density,and high power factor,and has broad application prospects in many fields such as high-speed electric spindles and fuel cell air compressors.At present,the control technology of HSPMSM has the following difficulties:(1)During the high-speed operation of the motor,the current cross coupling problem between the d and q axes is particularly prominent,which seriously affects the stability of the current loop;(2)Due to the small stator inductance of HSPMSM,the filtering effect of current harmonics caused by nonlinear factors of the inverter and the structural design of the motor body is poor,which increases the loss of the motor core and causes serious motor heating,resulting in torque ripple.Solving the above problems is of great significance for improving the stability of HSPMSM operation.Firstly,HSPMSM adopts magnetic field oriented control technology to establish a static decoupling model of HSPMSM through coordinate transformation,but dynamic coupling remains unresolved during high-speed operation.To further improve the stability of the current loop and address the serious problem of cross coupling in the current loop,a time-domain mathematical model of HSPMSM is established to analyze the causes of cross coupling;Then,a complex vector mathematical model of HSPMSM was established,and the control performance of traditional PI current regulators and complex vector current regulators was compared through zero pole plots and baud plots.Finally,the effectiveness of decoupling based on complex vector current regulator was verified through simulation,thereby suppressing cross coupling and improving the dynamic response performance of the current loop.Secondly,in response to the problem of small stator inductance in HSPMSM,which leads to high harmonic current components,the reasons for harmonic current generation due to nonlinear factors in the inverter are analyzed first,and a mathematical model of HSPMSM containing harmonics is established;A harmonic extraction module based on Butterworth filter is designed,and the direct current of a specific order harmonic can be obtained by setting the frequency in d-q coordinate system.Then a harmonic suppression algorithm based on super twisted sliding mode controller is proposed to suppress the 5th and 7th current harmonics.Finally,through simulation verification,after adding the harmonic suppression algorithm,the total harmonic content decreased from 10.93%to 2.81%,the 5th harmonic content decreased from 3.15%to 0.31%,and the 7th harmonic content decreased from 10.32%to 0.39%.Finally,a hardware experimental platform based on SiC devices was designed based on the power of the experimental motor,and experimental verification was conducted on this experimental platform.The results showed that the proposed method can effectively solve the cross coupling problem of HSPMSM and has good suppression effect on specific harmonics.The amplitude of the 5th harmonic decreased from 38.4dB to 21.3dB,and the amplitude of the 7th harmonic decreased from 28.8dB to 13.2dB.