Comprehensive Analysis of Hexagonal Sigma-Delta Modulations for Three-Phase High-Frequency VSC Based on Wide-Bandgap Semiconductors

TLDR: Modulations of single-loop and double-loop hexagonal sigma-delta modulations for voltage source converters that use silicon carbide (SiC) semiconductors greatly improve efficiency and generate fewer low-order harmonics than the SVPWM and VSFPWM strategies do.

Abstract: The efficiency of wide-bandgap (WBG) power converters can be greatly improved using high-frequency modulation techniques. This article proposes using single-loop and double-loop hexagonal sigma-delta (H- $\Sigma \Delta$ and DH- $\Sigma \Delta$ , respectively) modulations for voltage source converters (VSC) that use silicon carbide (SiC) semiconductors. These allow high switching frequencies to operate more efficiently than silicon devices. Thus, $\Sigma \Delta$ modulations are excellent candidates for taking advantage of WBG devices. The proposed modulation techniques allow working with a variable switching frequency, thus producing an extreme reduction in switching losses and mitigating the low-order harmonics in comparison with the classical space vector pulsewidth modulation (SVPWM) technique, and with the innovative variable switching frequency pulse-width modulation (VSFPWM). The performance and losses of both $\Sigma \Delta$ techniques are analyzed here using MATLAB/Simulink and PLECS, and then compared with SVPWM and VSFPWM. Furthermore, the frequency spectrum and the total harmonic distortion are evaluated. Experimental results performed on a VSC converter that uses SiC MOSFET s show how H- $\Sigma \Delta$ and DH- $\Sigma \Delta$ greatly improve efficiency and generate fewer low-order harmonics than the SVPWM and VSFPWM strategies do.