Nonintrusive method for estimating field efficiency of inverter-fed induction motor using measured values

This paper presents a nonintrusive method for estimating field efficiency of inverter-fed induction motor at various operating frequencies and loads using only a set of data from field measurement. The performances of motor such as torque and efficiency can be estimated by using measurement data coupled with the use of genetic algorithm based on the modified motor equivalent circuit concept. The 2.2 and 4.0 kW motors fed by inverter were tested in laboratory under frequencies of 30, 40, 50, and 60 Hz. The subway tunnel ventilation fan motors controlled by variable speed drive were also on-site investigated. The estimated performances found to give a better correlation over a wide range of speeds and loads.