Random Modulation in Inverters With Respect to Electromagnetic Compatibility and Power Quality

Random modulations are treated as one of the solutions for reducing conducted electromagnetic interference (EMI) in power electronics inverters. Although in papers related to inverters, this view has not been clearly demonstrated. Especially in the state-of-the-art papers related to randomly modulated inverters, it is hard to find information about EMI measurement procedures or deeper EMC analyses. Therefore, this paper will discuss the influence of random modulations used in power electronic inverters on selected issues related to inverter EMC and power quality. A complete case study is carried out on a three-phase inverter. The undertaken analysis refers to the generation of interference, EMI measurement methodology, the conditioning of EMI filtration, and the quality of output voltage. The results show which EMI parameters are improved and which parameters are aggravated, when random modulation is used. The presented results show that random modulation should be applied in inverters with great caution. In addition, we show the limitations of EMI measurement methods and propose a more reliable way to assess the EMI spectrum.