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

Abstract

International efficiency testing standards such as the IEEE 112-B and IEC 34-2-1 can determine an induction machine's efficiency accurately at the cost of hindering the machine's productivity. Alternatively, various methods used to determine a machine's efficiency in-situ do so at the cost of accuracy. This paper proposes a method that determines an induction machine's efficiency over a range of load conditions from tests conducted and centered around one thermally stable load point in the least intrusive manner possible. The results are then compared to those of the IEEE 112-B and IEC 34-2-1 motor testing standards using segregated loss analysis. It was found that despite the proposed algorithm being unable to accurately determine core losses, the efficiency of a machine can be estimated to within 0.5-2.1% and 1.1-1.7% error when compared to the IEEE 112-B and IEC 34-2-1 standards respectively over a 25-150% machine load profile (dependent upon the proposed method's implementations).

In-Situ Efficiency Estimation of Induction Motors Based on Quantum Particle Swarm Optimization-Trust Region Algorithm (QPSO-TRA)

“…T load,Est = I load I rated (T rated − T ambien ) + T ambien (1) where I rated is the rated load current stated on the machine's nameplate, I load is the actual load current, T load,Est is the actual temperature, T ambien is the ambient temperature, and T rated is the rated load temperature…”

“…While effort is being made to design and manufacture more efficient induction motors (IMs), monitoring a machine's operational efficiency helps reduce energy costs by ensuring that it is running in its optimal efficiency range. Numerous works have been published for estimating the efficiency of the electrical machines in situ, under the loaded condition without disturbing their operation [1,2]. To assess energy efficiency and enhance the overall performance of the industrial processes, it is essential to identify energy loss and monitor the efficiency in real time [3].…”

Experimental Study for the Assessment of the Measurement Uncertainty Associated with Electric Powertrain Efficiency Using the Back-to-Back Direct Method

“…The authors obtained similar results in Reference [23], where the difference between the measured and estimated efficiency was 0.4% for a 3 kW rated power. In Reference [27], for an 11-kW rated power induction motor, the Realistic Error Estimation (REE) was ±0.24%, which was lower than the Worst Case Estimation (WCE) of the method recommended by the IEEE 112-B standard for polyphase induction motors. In Reference [28], the accuracy difference for a 3-hp machine, when comparing the measured and estimated efficiencies, was 1.2%.…”

“…The increasing demand for the use of small AC motors has stimulated research related to the development and enhancement of techniques for the measurement of the motors' efficiency, and for the computation of the associated accuracy [18][19][20][21][22][23][24][25][26][27][28], where we provide a short review of the related research papers. In Reference [9], a comparative analysis of direct and indirect efficiency estimation techniques was presented for a 3 kW, three-phase induction motor, and it was concluded that the direct determination of efficiency should be used for all sizes of induction motors.…”

Treatment Strategy Research on a Squirrel-Cage Induction Motor with Broken Rotor Bar Faults

“…Here, the iron loss and copper loss of the motor are calculated, and the relationship between the power loss of the motor and its equivalent circuit parameters is obtained. To reduce interference in the operation, the efficiency change of an induction motor under different load levels is studied in the form of an equivalent circuit in paper [27]. Here, the calculation accuracy is exemplary.…”