Robust Notch Filter-Based Active Damping Design for LCL-Equipped High-Speed PMSMs Considering Dual Resonance Problem

In this article, the dual resonance problem is first described in LCL-equipped high-speed permanent magnet synchronous motor drives. Since the synchronous coordinate transformation, the natural resonance in stationary coordinate will be converted into two resonances, which are located at
$f_{\text{res}}-f_{e}$
and
$f_{\text{res}}+f_{e}$
, respectively. (
$f_{\text{res}}$
is the natural resonant frequency and
$f_{e}$
is the motor frequency). Theoretical analysis and experimental results indicate that the traditional notch filter-based methods cannot ensure stability when the
$f_{\text{res}}$
is located between
$f_{s}/3-f_{e}$
and
$f_{s}/3+f_{e}$
because of the dual resonance problem. To address this issue, a robust notch filter-based active damping with a magnitude attenuator is proposed. Besides, the coefficient selection method of the magnitude attenuator is analyzed in detail. Finally, the effectiveness and robustness of the proposed method are verified by the experimental results of a 72 kr/min motor.