A nonlinear positioning controller for an induction motor

The application of a two degrees of freedom nonlinear controller to an induction motor is presented. The control structure proposed has been obtained by combining the standard geometric nonlinear model matching and disturbance decoupling feedback structures. The resulting control law is composed of a simplified model of the motor, a tracking (or reference model) and a regulation filter. Its implementation only requires measurements of the shaft position, but no attempt to estimate the motor states is made. Instead, an output error dynamics estimation is performed. The scheme proposed leads to a two degrees of freedom controller, where the performance is determined by the tracking model, in the same manner as in the model matching problem. Meanwhile, the robustness properties are defined by the regulation filter. A major feature of the control structure proposed, is that it is much more simple to analyse and implement, than previous nonlinear control-observer solutions proposed. The effectiveness of the approach is shown through a series of nonlinear simulations