Constant Common-Mode Voltage Strategies Using Sigma-Delta Modulators in Five-Phase VSI

This article proposes and studies different sigma-delta (\Sigma\Delta) modulation strategies for obtaining a constant common-mode voltage (CMV) by eliminating the CMV level transitions in a five-phase voltage source inverter (VSI). These techniques are based on choosing vectors that generate a constant CMV with values of 0.1V_{\text{dc}} or -0.1V_{\text{dc}}. Because of the high-switching frequencies used with wide-bandgap semiconductors, pulse-width modulation techniques continually generate high d v /d t values. Therefore, the proposal to combine a \Sigma\Delta modulation strategy with vector selections achieves a constant CMV level due to the elimination of its level transitions, a reduction in conducted electromagnetic interference and a high-efficiency converter operation. The average number of switching per transistor of the VSI is analyzed using the results from MATLAB/Simulink and PLECS simulations. Experimental results are obtained by applying the proposed \Sigma\Delta modulation strategies on a VSI with silicon carbide MOSFETs. The results demonstrate the achievement of the aforementioned features.