Synchronous Estimation Scheme of PMSM Mechanical Parameters: A Decoupled Extended Sliding Mode Observer

In the permanent magnet synchronous motor drives (PMSM), high-quality controller optimization and condition monitoring rely heavily on accurate knowledge of mechanical parameters. To address this need, this study presents a novel decoupled extended sliding mode observer (DESMO) capable of achieving high-quality synchronous estimation of the moment of inertia and the load disturbance. An extended state-space equation is, firstly, constructed by extending the mechanical equations. Subsequently, the novel DESMO is designed by introducing two new recursive equations. On this basis, the excitation weight on the moment of inertia is analyzed, resulting in the derivation of Lyapunov-mechanism-based decoupling updating conditions (DOCs) to further exploit the DESMO's estimation potential. Furthermore, when the DOCs are not all satisfied, the second observation equation is derived with the reaching law of the moment of inertia set to zero to achieve state decoupling during estimation process. With the switching excitation of DOCs, notably, the DESMO is capable of serving as a more competitive candidate for observing multi-mechanical parameters, as demonstrated through simulation and experimental results.