A nonlinear tracking control for sensorless induction motors with uncertain load torque

We propose a novel nonlinear tracking control algorithm for induction motors with uncertain load torque in which only stator currents are used for feedback: rotor speed and flux sensors are not required; no open‐loop integration of flux dynamics is used. For a class of reference signals, for sufficiently small computable time‐varying load torque uncertainty and for any initial condition belonging to an explicitly computed region, closed‐loop boundedness is guaranteed while, under persistency of excitation, local exponential rotor speed and flux modulus tracking are achieved in the case of constant load torque.