Hybrid Control of Permanent Magnet Synchronous Motor Using Unknown Input and Extended State Observers with Improved Inter-Axis Decoupling

This paper presents a novel hybrid observer-based control framework integrating Unknown Input Observer (UIO) and Extended State Observer (ESO) for robust disturbance rejection performance and reduced <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$d q$</tex>-axis current coupling in Permanent Magnet Synchronous Motor (PMSM) drives. The proposed approach addresses the dual challenges of disturbance caused by the VSI-fed PMSM, motor design traits, and parameter uncertainties, as well as inter-axis coupling that degrades dynamic performance. The UIO is employed to estimate and compensate for structured disturbances and unmodeled inputs, such as load torque variations. Concurrently, the ESO estimates lumped disturbances, including parameter mismatches and external disturbances, and provides real-time compensation to enhance control system reliability. The hybrid observer design is developed to ensure accurate state estimation while maintaining low computational complexity, and achieving improved decoupled <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$d q$</tex> axis current control. Simulation results of a laboratory prototype PMSM demonstrate considerable control performance improvement, compared to other similar observer-based methods, establishing a comprehensive framework for control of PMSM drives in high-power industrial and automotive applications.