Observer-based online parameter estimation of squirrel-cage induction machines based on the gradient descent method

This paper deals with the online parameter estimation of squirrel-cage induction machines using the Gradient Descent Method and coupled stator and rotor flux observers. Stator resistance, rotor resistance and mutual inductance can be estimated in real time. The presented approach is applicable on a standard industrial drive, including a current measurement and a motor speed feedback. The adaptation algorithm is described with simple analytical terms. The performance has been demonstrated by experiments. Furthermore, the influence of an asymmetrical stator winding, saturation and incorrectly assumed leakage inductances are discussed.