Stabilization of Controlled Current Induction Motor Drive Systems via New Nonlinear State Observer

In this paper a new bilinear and nonlinear second-order state observer which is globally asymptotically stable is constructed to estimate the unmeasurable state variables. Then an unstable controlled current induction motor drive system which cannot be stabilized by a linear state observer is successfully stabilized by feeding the reconstructed state variables from the nonlinear observer to the frequency control channel. This scheme is easily implementable, resulting in an asymptotically stable overall closed-loop system. These results are numerically verified by simulation.