Nonintrusive efficiency estimation of induction machines using parameter identification based on steady state stator current curve

The equivalent circuit method is one of the promising methods for induction machine efficiency estimation. Conventionally, parameters of the machine are usually obtained from a no-load and lock rotor test. For in-service induction machines, performing these tests may not be possible without disrupting the machine operations. In this paper, a nonintrusive equivalent circuit based efficiency estimation method using Artificial Bee Colony (ABC) optimization algorithm is proposed for in-service induction motors. The parameter identification scheme minimizes the error between the measured and estimated steady state stator dq currents for various slip speed values ranging from no-load to full load condition. Efficiency estimates using the identified parameters at specific loading points for a 7.5kW motor are presented. Finally, the results are compared to the IEEE standard 112 test method B and the direct measurement from an in-line torque transducer. An error within 0.808%-0.295% is obtained on a 50%-100% loading range when compared to the IEEE method B.