Observer based magnetic flux estimation of induction motors

This paper presents an observer design methodology for a estimation of magnetic flux estimation of induction motors. First, we characterize the class of MIMO nonlinear systems of induction motors that consists of the linear observable part and the nonlinear part with a block triangular structure. Also, the similarity transformation that plays an important role in proving the convergence of the proposed observer is generalized to the MIMO systems. Since the gain of the proposed observer minimizes a nonlinear part of the system to suppress for the stability of the error dynamics, it improves the transient performance of the high gain observer. Moreover, by using the generalized similarity transformation, it is shown that under some observability and boundedness conditions, the proposed observer guarantees the global exponential convergence to zero of the magnetic flux estimation error.