Methods measure power electronics efficiency

Focus:

This short article describes two techniques for measuring the efficiency of high-power power converters that provide power to motors, generators, industrial equipment and other loads. These test techniques eliminate the need for a power source capable of delivering the full input power expected by the power converter in the application. One test method shorts the load of the power converter under test and configures the power converter so that it develops circulating reactive power to achieve the desired current levels and frequency on the converter's input and output. This requires that the power converter allows the user to adjust its power factor or that the designer be able to modify the power converter's control algorithm to create reactive power. Using this first test method, the power source delivers real power equal to the losses in the power converter plus the necessary reactive power. A second method adds another power converter (like the one under test) to cancel out the reactive input current draw by the converter under test.

What you’ll learn:

• How to measure the efficiency of high-power motor drives and other power converters without applying full input power

Notes:

The techniques described here have been used by the author's company to measure the efficiency of a 125-kW power system.

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Author & Publication:

Liping Zheng, Calnetix, Yorba Linda, CA; Edited by Martin Rowe and Fran Granville , EDN, Jul 29 2010

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