On-line stator and rotor resistance estimation for induction motors

A ninth-order estimation algorithm is designed which provides online exponentially convergent estimates of both rotor and stator resistance for induction motors, when persistency of excitation conditions are satisfied and the stator current integrals are bounded, on the basis of rotor speed, stator voltages, and stator current measurements. Rotor flux is also asymptotically recovered. Experimental tests are reported which show that: persistency of excitation and boundedness of stator currents integrals hold in typical operating conditions; both resistance estimates converge exponentially to true values; the algorithm is implementable online by currently available digital signal processors; and the algorithm is robust with respect to modeling inaccuracies. The proposed estimation scheme is intended to improve performance and efficiency of currently available induction motor control algorithms.