Initial findings in electromagnetic emissions above 30 MHz from power inverters and variable speed motor controllers

This paper describes research being done at the University of Wyoming (USA) on radiated emissions from power inverters and variable speed motor controllers/adjustable speed drives (ASDs) of 5 kW and larger size. Measurements have been done in the frequency range 30 MHz to 1 GHz using an EMC precompliance test system. Most measurements were performed in-situ. These measurements have found that these devices are radiating noise at frequencies up to 800 MHz. Sample graphs showing the measurements are given as well as a table summarizing some measurement results