Conducted emission measurements in the power electronics environment

The University of Nottingham and several industrial partners are undertaking a project to investigate EMC in variable speed drives and the power electronics environment. Electronic drives are complex systems from a EMC point of view as they contain many subsystems which will contribute to emissions over a wide frequency range, e.g. mains frequencies, high power switching in the 100 kHz range and microprocessor clocks in the 100 MHz ranges. The overall objective of the work is to produce computer based tools that can be used to predict EMC performance of various drives at the design stage. The initial work has involved measurement and simulation of conducted emission modes. The paper identifies the methods used for the measurement of conducted emissions and highlights some of the important points to consider in making meaningful and repeatable measurements.