On-line stator and rotor resistance estimation for induction motors

A ninth-order estimation algorithm is designed which provides on-line expon entially convergent estimates of both rotor and stator resistance for induc tion motors, when persistency of excitation conditions are satisfied and th e stator currents integrals are bounded, on the basis of rotor speed, stato r voltages, and stator currents measurements. Rotor flux is also asymptotic ally recovered. Experimental tests are reported which show that: persistenc y of excitation and boundedness of stator currents integrals hold in typica l operating conditions; both resistance estimates converge exponentially to true values; the algorithm is implementable on-line by currently available digital signal processors; and the algorithm is robust with respect to mod eling inaccuracies. The proposed estimation scheme is intended to improve p erformance and efficiency of currently available induction motor control al gorithms.