A Cascaded Current Harmonics Suppression Method Considering Steady-state and Dynamic Characteristics for PMSM Based on Quasi-Resonant Extended State Observer

The issue of current harmonics caused by inverter nonlinearity factors affects the high-quality operation of PMSM. Dynamic suppression is important and affects the whole suppression effect. However, it is usually ignored because the transition process is brief. Therefore, a current harmonics suppression method considering steady-state and dynamic characteristics for PMSM based on quasi-resonant cascaded extended state observer (QR-CESO) is proposed. Firstly, according to the cascaded characteristics, a composite QR-ESO is applied to pre-estimate the target current harmonic, while an additional ESO is cascaded to re-estimate the remnant one, and thus the current harmonics are estimated as much as possible to improve the steady-state suppression performance. Secondly, benefiting from the collaborative characteristics, the multiple state variables of QR-CESO reasonably cooperate with each other and simultaneously estimate the current harmonics, and thus the dynamic suppression performance of QR-CESO is improved. Furthermore, the steady-state and dynamic characteristics are analyzed by the theoretical derivation and frequency domain analysis. The stability and parameter design are verified through the discrete domain analysis. Finally, the proposed scheme is verified on a 17.26-kW PMSM drive system.