A Comparative Study on Reduced-Order Disturbance Observer-Based Optimal Control Strategies for Surface-Mounted PMSM Drives

This paper proposes a simple 1
^st
-order disturbance observer (DO)-based optimal control (DOBOC) strategy for surface-mounted permanent magnet synchronous motor (SPMSM) drives. A detailed comparative analysis of three reduced-order (i.e., 1
^st
, 2
^nd
, and 3
^rd
) DOs has been presented in terms of structural complexity along with transient and steady-state performances. A simple 1
^st
-order DOBOC is proposed with a considerably simple and easy gain tuning procedure without any complex equation and time-consuming weighting matrices selection while ensuring a competitive control performance. Also, the stability of three DOBOCs is proven using the Lyapunov function, which has not been carried out in the previous studies. Furthermore, this paper provides a detailed procedure to systematically select the controller and observer gains of three reduced-order (i.e., 1
^st
, 2
^nd
, and 3
^rd
) DOBOC by experiment. Comparative experiments are performed to confirm the feasibility of the proposed 1
^st
-order DOBOC using a prototype SPMSM test-bed with a TI TMS320F28335 DSP. Finally, verification results and comparative table are presented to compare the speed tracking performance (e.g., transient response, undershoot (US), steady-state error (SSE), and robustness to load torque disturbances) of three reduced-order DOBOC methods under speed and load torque step-changes.