A Robust Encoderless Control for PMSM Drives: A Revised Hybrid Active Flux-Based Technique

Hybrid active flux estimation technique takes advantage of both the voltage model for high-speed operation and the current model for low-speed, which considerably enlarges the system operating range. However, the accuracy of the motor parameters, particularly the stator resistance, severely impacts the robustness of this technique, especially at low speeds ( $\leq 5$ % per unit). In this work, we propose a new robust hybrid active flux observer-based technique, which is simple in structure and realization, but immune to stator resistance variations. It further broadens the operation region from standstill to full speed and has fast control dynamics. The proposed solution is verified via experimental data at a lab-constructed test bench. Results confirm that the proposal achieves good control performances at both low and high speed ranges, and is robust against parameter mismatches and load disturbances.