217 – Creating Efficiency Maps for 3-Phase Induction Motors

Application Note / Model Data

Overview

Due to advances in the variable speed drive technology of induction motors, its application to fields requiring wide drive ranges is making progress. Efficiency maps for drive ranges are available as an effective method of evaluating the properties of induction motors in these industries.
In order to create an efficiency map on actual measurements or on the computer, it is necessary to search for the highest efficiency point by allocating rotation speeds, voltage, and slip in the drive range at each load point as parameters. This would lead to vast amounts of calculations and would require time to organize the results. To help with this problem, efficiency maps can be easily obtained by creating a JMAG-RT model of the target as well as using JMAG-RT Viewer’s efficiency map calculation function.
In this example, the use of JMAG-RT Viewer to create efficiency maps for three-phase induction motors when drive temperatures change.

Efficiency Map

Fig. 1 and Fig. 2 show the efficiency map when the drive temperature is changed to 20 deg C and 120 deg C.
In the figure, it is possible to ascertain the efficiency of each drive state. Also, as the temperature rises, we can see that efficiency decreases.

Loss Map

Fig. 3 and Fig. 4 show the stator copper loss map when changing the drive temperature to 20 deg C and 120 deg C, and Fig. 5 and Fig. 6 show the rotor copper loss map. When the temperature is high, you can see that copper loss on the primary and secondary sides gets larger. This is because the electrical characteristics of the primary coil and secondary conductor degrades, and the electrical resistance increases which leads to a decrease in efficiency.

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