A formal finite-control-set control approach for PMSM drives under disturbances

This paper proposes a formal finite-control-set (FCS) control method based on the control Lyapunov function (CLF) for permanent magnet synchronous motors (PMSM) with disturbances. The unique feature of the proposed method is that the formal stability of a closed-loop system with discrete control inputs in the presence of disturbances is rigorously guaranteed. A reduced-order generalised proportional integral observer (GPIO) technique is first introduced to estimate unknown disturbances.

Second, unlike previous work, the estimated term is integrated into the design of a disturbance observer-based (DOB) input-tostate stable (ISS) control Lyapunov function. The optimal switching states are selected by solving a quadratic programme (QP) subject to the FCS constraint and the proposed DOB-ISS-CLF constraint. A rigorous theoretical proof of closed-loop stability is provided for the advocated control law. Finally, the benefits of the proposed approach are demonstrated in the presence of step / time-varying speed reference signals, step / time-varying load torque disturbances, and parameter uncertainties.