Patent ID: 7250739

Claim:
A method for estimating the rotor time constant (τ r ) of an induction machine when the stator resistance (R s ) and rotor resistance (R r ) of the induction machine are known, the method comprising: feeding a DC current to the stator of the induction machine, injecting a sine-wave current component into the stator of the induction machine, the current having an amplitude (i sc ) and an angular frequency (ω c ), measuring the voltage component (u scd ) of the stator voltage of the induction machine in the same direction and with the same angular frequency as the injected current, and calculating the rotor time constant using equation τ r = 1 ω c ⁢ u scd - R s ⁢ i sc ( R s + R R ) ⁢ i sc - u scd .