Comparative study of two robust online rotor resistance estimators for induction machine adaptive control

This paper presents two adaptive variable structure identifiers that provide finite time convergent estimate of the induction motor (IM) rotor resistance under feasible persistent of excitation condition. Experiments show that both approaches achieved very good estimation of the rotor resistance which is subjected to online large variation (up to 75%) during operation of the induction motor and are robust with respect to the variation of the stator resistance (up to 100%), measurement noise, modeling errors, discretization effects and parameter uncertainties. The results illustrate globally the superiority of the second approach. Important advantages of the proposed algorithms include that they are suitable for IM adaptive control and are relatively simple to implement in real-time.