AC Induction Motor Stator Resistance Estimation Algorithm

Stator resistance identification algorithm for AC induction motor is presented in this paper. It does not require additional external excitation. The algorithm is intended to capture slow variations of stator resistance which are given by the changes in stator windings temperature. Steady state operation with harmonic voltages and currents are located during the operation of the motor and the stator resistance is determined from RMS values of the voltage, current and from actual active power. Simulation experiments have proved the theoretical expectations. The algorithm is not computationally intensive which makes it suitable for real time implementation in reasonable hardware. The experimental results confirm that the proposed method gives acceptable results on a real motor. The disadvantage is the dependency of the stator resistance estimate on the level of magnetic flux excitation. The off line measurement of stator inductance on excitation current is proposed to solve this problem. Key–Words: AC induction motor, stator resistance, identification, on-line