Fast-Processing Sigma–Delta Strategies for Three-Phase Wide-Bandgap Power Converters With Common-Mode Voltage Reduction

The electromagnetic compatibility of wide-bandgap (WBG) power converters can be greatly improved using spread-spectrum modulation techniques. This article proposes a family of reduced common-voltage sigma–delta modulations (RCMV-
$\Sigma \Delta$
) for voltage source converters (VSC) that use gallium nitride (GaN) semiconductors. Specifically, this article proposes three new techniques: two reduced-state sigma–delta modulations (RS-
$\Sigma \Delta 1$
&2), and an active sigma–delta strategy (A-
$\Sigma \Delta$
). The proposed modulation techniques reduce or eliminate the common-mode voltage (CMV)
dv/dt
transitions and suppress the noise spikes in the conducted electromagnetic interference spectrum. Furthermore, this article proposes the use of fast-processing quantizers for RCMV-
$\Sigma \Delta$
techniques as well as for hexagonal sigma–delta (H-
$\Sigma \Delta$
). These quantizers use a novel calculation methodology that simplifies the implementation of the proposed modulations and considerably reduces their computational cost. The performance and the total harmonic distortion (THD) of RCMV-
$\Sigma \Delta$
techniques are analyzed here using MATLAB/Simulink and PLECS. Experimental results performed on a VSC converter that uses GaN e-HEMTs show how RCMV-
$\Sigma \Delta$
techniques considerably improve electromagnetic compatibility and exhibit similar efficiencies and THD to those of H-
$\Sigma \Delta$
.