Model-Free Deadbeat Direct Speed Control with Adaptive Bandwidth Factor in Surface-Mounted Permanent Magnet Synchronous Motor

This paper presents a model-free deadbeat predictive direct speed control strategy for surface-mounted permanent magnet synchronous motors incorporating an adaptive-bandwidth extended state observer. Unlike conventional extended state observers with fixed bandwidth factors, which lack adaptability under varying conditions and introduce coordination difficulties between speed and current loops, the proposed method presents an observation-error-driven bandwidth adjustment mechanism. This method enables real-time and independent adjustment of the bandwidth factors for the lumped disturbance observers of speed and current, thereby dynamically balancing disturbance rejection and estimation accuracy under various operating conditions and enhancing the algorithm's adaptability. To ensure theoretical stability, an integral-type Lyapunov function is constructed to guarantee the asymptotic convergence of the proposed adaptive bandwidth observer. Moreover, practical guidelines for parameter design principles are formulated to facilitate the implementation of the proposed method. Experimental results on a 750W SPMSM platform demonstrate that the proposed strategy significantly improves transient performance and adaptability compared to fixed-bandwidth observer-based approaches.