Tuning of PI gains for FOC of induction motors with guaranteed stability

It is well known that the performance of field oriented controllers (FOC) for induction motors critically depends on the tuning of the gains of the PI velocity loop. In this paper, the authors give some simple rules to carry out this task ensuring robust stability vis-a-vis uncertainty in the rotor time constant. The main contribution of their work is an algorithm that, for each setting of the PI gains, evaluates the maximal error of the rotor time constant estimate for which (global) stability is guaranteed. Instrumental for their study is the exploitation of a passivity property of FOC. The analysis is carried out by invoking some standard Lyapunov stability arguments