A two stage control scheme towards stability and robustness for PMSMs with unknown load torque

The issue of developing a robust control scheme for permanent magnet synchronous motors is investigated. Towards this aim a two stage control scheme is proposed. The inner loop controller is a robust controller of the feedback linearization type with degrees of freedom satisfying I/O decoupling and pole assignment for the motor's currents. The outer loop controller is a PI controller regulating the angular velocity of the rotor. The conditions for the stability of the overall closed loop system are derived in the form of analytical inequalities covering also the issue of robustness of the closed loop system. The internal and external controllers' degrees of freedom are determined metaheuristically, through computational experiments.