Sensorless control strategy for SPMSM with improved full-order sliding mode observer and novel converged switching strategy

In pursuit of improving both the estimation accuracy and dynamic performance of sensorless control technology of surface-mounted permanent magnet synchronous motor (SPMSM), this article proposes the higher-order terminal sliding mode control on the basis of the full-order state equation. Through rigorous theoretical derivation, this study substantiates the stability and rapid convergence of the proposed scheme. Meanwhile, this research addresses the demands of a wide speed range by introducing a novel adaptive switching strategy. This strategy dynamically modulates the amplitude of the square-wave injected signal in response to variations in motor speed. This approach mitigates the impact of the injected signal amplitude on the sliding mode observer within the transition zone and it facilitates smooth transitions between the two sensorless control algorithms. Finally, the overall control scheme is validated through experimental results, demonstrating the capability to achieve wide speed range acceleration and deceleration from 0 to 1000 r/min, and seamless transitions between the two control strategies.