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- $\Sigma \Delta$ .