71% Common-mode voltage suppression modulation strategy for indirect matrix converters

Common-mode voltage (CMV) with a high amplitude and frequency is generated when an indirect matrix converter (IMC) is operating, which damages the motor winding insulation and accelerates motor aging. Existing IMC modulation methods can only suppress the CMV by 42.3%. However, this paper proposes a modulation strategy with a 71% reduction in the peak CMV. The proposed method selects active vectors based on the characteristics of the CMV amplitude under each of the active vectors. The rectifier stage selects two active vectors within each modulation sector. According to the sector where the input reference current vector is located, the inverter stage chooses active-voltage vectors whose corresponding peak CMV is 1/3 the minimum peak line voltage for modulation. Moreover, the CMV spikes caused by the dead zone effect are eliminated by reasonably arranging the switching sequence of the voltage vectors in the inverter stage. The proposed approach considerably lowers the peak CMV and has a good suppression effect on the amplitude of high-frequency CMV. Finally, experimental results illustrate the CMV reduction efficiency of the modulation strategy.