Method for automated measurement of the ohmic rotor resistance of an asynchronous mechine

Abstract

Method for automated measurement of the ohmic rotor resistance (Rr) of an asynchronous machine (1) controlled via an inverter (8) while being acted upon by a non-rotating field, the method involving a. measuring the ohmic stator resistance (Rs), the leakage inductances (Lσs, Lσr) and the main inductance (Lm) of the asynchronous machine, b. leading a testing signal (Usa) being formed by a predetermined direct signal with a superimposed alternating signal to a phase winding (a) of the asynchronous machine, the frequency of the alternating signal corresponding approximately to the nominal slip frequency (fs) of the asynchronous machine (1), c. measuring the amplitude and the phase (φ) of the phase signal ({overscore (I)}sa) resulting from the testing signal, and d. calculating the ohmic rotor resistance (Rr) from the measured values according to a) and c). Measuring the ohmic rotor resistance in accordance with this method can be performed in a very short time, when the inductances and the ohmic stator resistance are known. Further, current displacement does not appear due to the low frequency of the alternating signal.

Dependencies are inferred from the claim text.