Modified Single-Edge Modulation to Decrease Common-Mode Voltage With Considering Deadtime Effects and Switching Losses for Three-Phase VSIs

As the switching frequency of power semiconductor devices increases, it is necessary to suppress the common-mode voltage (CMV) generated by the pulsewidth modulation action of the voltage-source inverters, which can produce serious electromagnetic interference (EMI) and hazards, such as motor axial current. This article proposes a modified modulation technique based on the single-edge carrier form to decrease the amplitude and frequency of CMV by selecting different combinations of active voltage vectors in different voltage vector sectors. On this basis, the method of optimizing the sequence of voltage vector action is adopted to reduce the switching losses of the inverter and designing a reasonable carrier frequency variation function based on the mathematical derivation, considering the phase angle of output current and distribution characteristics in the time domain of switching frequency, which is combined with the above-modified modulation strategy to further restrain the switching losses and differential-mode conducted EMI. Moreover, a deadtime effect correction methodology for estimating the phase current at the moment of switching action is introduced to eliminate the CMV spikes during the deadtime interval. Finally, the experimental platform is built to validate the effectiveness and practicality of the modified single-edge modulation technique.