Influence of the inverter´s modulation technique on the audible noise of electric motors

The noise emissions of inverter-driven electric motors are highly influenced by additional electromagnetic noise generated by the current harmonics from inverter operation. The amplitude and the frequency of these harmonics depend on the modulation technique applied in the power electronic converter. Purpose of this paper is to highlight the important role that the modulation techniques play in the noise generation in variable speed drives and analyze the different characteristics of the current harmonics as well as of the generated noise. A good understanding of the available choices and their characteristics, advantages and limitations is necessary in order to optimize the acoustic design of the “motor-converter” system.