Critical Damping Double Integral Control for PMSM Speed Control Applications via Order Reduction Technique

This study presents an advanced q -axis current-independent feedback system design technique for permanent magnet synchronous motors (PMSMs), which robustly regulate speed and d -axis current in the presence of model-plant mismatches. The contributions of this study are summarized as follows: 1) model-independent pole-zero cancellation (PZC) filters for the position, speed, acceleration, and d -axis current, to improve closed-loop accuracy; 2) simple filter-based double integral control laws for speed and d -axis current, involving feed-forward terms by the filtered signals and disturbance observers; and 3) assignment of the critically damped transfer function to the closed-loop system through high-order PZC technique for the feedback system gains. An experimental study with a 700-W PMSM dynamo validates the practical effectiveness of the beneficial closed-loop analysis results.