An Algorithm for Nonintrusive In Situ Efficiency Estimation of Induction Machines Operating With Unbalanced Supply Conditions

Abstract

The development of an in situ efficiency estimation technique is a challenging task where the lowest level of intrusion and the highest possible accuracy are required. In this paper, a new algorithm is discussed for the in situ efficiency estimation of induction machines under unbalanced power supplies. Prior work in the literature has concentrated on balanced supplies. In addition, to have a nonintrusive speed measurement, a specific adaptive nonlinear algorithm is applied for the extraction of the speed-dependent current harmonics from the measured current signal. A similar algorithm is used to extract the symmetrical components from the current and voltage signals to handle the unbalanced supply conditions. Experimental results with two different machines are used to prove the effectiveness and generality of the proposed method. Measurement error analysis, as well as repeatability tests, has been done to determine the credibility of the proposed method.Index Terms-Error analysis, evolutionary algorithm, induction motor, in situ efficiency estimation, nonlinear adaptive filter, repeatability test, unbalanced supply.

Analysis of a Nonintrusive Efficiency Estimation Technique for Induction Machines Compared to the IEEE 112B and IEC 34-2-1 Standards

“…Given that [12] reported that accurate speed estimates implementing vibration analysis can be ascertained in 3 seconds (as opposed to [11] requiring 60 seconds), it is suggested that any real-time implementation of the NIEE-PBIL utilizes vibration analysis. This is due to the nature of the test requirements requiring measuring a machine's power profile at a singular thermal load point.…”

“…An alternative implementation of determining speed from a motor's current signature is proposed in [11], where speed dependent harmonics that can be found in the stator current which are related to the supply frequency are extracted using a non-linear adaptive algorithm. The aforementioned method is able to estimate a machine's speed to within 0.07% of the measured speed [11].…”

“…The aforementioned method is able to estimate a machine's speed to within 0.07% of the measured speed [11].…”

“…Due to the brief time at which the differing loads are kept, the operating temperature at these incidental load points are assumed to be equal to that of the 'stable' load point. The result of having varying load points at the same thermal condition results in a non-singular set of data available in order for the optimization algorithm to converge to a unique solution [11]. The measured values are instantaneous 3-phase line voltages and currents supplied to the induction machine.…”

Software Sensor for Airflow Modulation and Noise Detection by Cyclostationary Tools

“…To develop the software sensor, we propose a non-linear algorithm to obtain the frequency information. The technique used was introduced in [17,18]. It is mainly used for signals encountered on electrical domain.…”