217 – Creating Efficiency Maps for 3-Phase Induction Motors

Application Note / Model Data

Overview

Due to advances in the variable speed operation technology of induction motors, applications to areas requiring a wide range of operation are progressing. As an effective way to evaluate the characteristics of induction motors in such areas, efficiency maps can be used in the operating region.
To create efficiency maps using actual measurements or computations, it is necessary to search for the highest efficiency point by using voltage and slip as parameters for each rotation speed and load point. Doing this makes the analysis execution enormous, taking time to output the results as well. With JMAG, efficiency maps can easily be obtained by creating a JMAG-RT model which is a plant model and using the efficiency map creation function in JMAG-RT Viewer.
In this example, JMAG-RT Viewer is used to create efficiency maps of a 3-phase induction motor when the driving temperature has been changed.

Efficiency Map

Fig. 1 and Fig. 2 show the efficiency maps when the drive temperature is changed to 20 deg C and to 120 deg C respectively. From the figures, the efficiency for each drive condition can be understood. Also, as the temperature rises, it can be seen that the efficiency becomes worse.

Loss Map

The stator copper loss map for when the drive temperature is changed to 20 deg C and to 120 deg C is shown in Fig. 3 and Fig. 4 respectively, and the rotor copper loss map is shown in Fig. 5 and in Fig. 6.
When the temperature is high, it can be seen that the copper loss on the primary side and the secondary side is large. This is because the electrical characteristics of the primary coils and the secondary conductors deteriorate and the electrical resistances increase, which leads to a decrease in efficiency.

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