Method for estimating the rotor time constant of an induction machine
View Patent ↗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 comprises the steps of 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 .
1. 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
.
2. A method according to claim 1 , wherein the frequency of the injected sine-wave current is selected to be 1/τ e , where τ e is an estimate for the rotor time constant.