A Noninvasive External Flux Based Method for In-Service Induction Motors Torque Estimation

This paper presents a novel method to determine the electromagnetic torque of grid-powered induction machines (IM). The torque determination constitutes a key point for the energy diagnosis and for choosing the well adapted motor in industrial processes. The proposed method is noninvasive as it is based on the measurement of the current and the magnetic external flux around induction machines. The torque estimation protocol is explained and experimental validations are made with an 11 kW IM. The impact of supply voltage variations on the accuracy of the proposed method is also analyzed.