Observer design for control and fault detection of an induction motor

A nonlinear observer has been designed for an induction motor using a parametric eigenstructure assignment design procedure. With a fixed gain observer the error dynamics are a function of speed and for some operating points the error can diverge. The nonlinear observer has a gain matrix which is a function of speed which keeps the eigenvalues of the error response dynamics in fixed locations. The design, although simple in concept, would not have been possible without the power of the MATLAB Symbolic Math Toolbox. Using SIMULINK it has been possible to set up and test the observer within the complete traction model.