Five-Level Hybrid Active-NPC H-Bridge Converter With Novel Space-Vector-Modulation Scheme

This article presents a five-level hybrid active-neutral-point-clamped H-bridge (HANPC H-bridge) converter topology for a single-phase system. The proposed HANPC H-bridge topology utilizes a combination of silicon (Si) and silicon carbide (SiC) switches to enable high switching frequency operation. Furthermore, a novel space-vector-modulation (SVM) scheme is proposed to switch the two legs of the proposed converter at different switching frequencies. For this, a generalized approach to control relative difference in the switching frequencies of the two converter legs based on converter switching losses is proposed. Using the proposed modulation scheme, HANPC H-bridge converter features reduced switching losses, improved harmonic performance of output voltage and current, and optimal device utilization to achieve low cost at high efficiency. Moreover, a closed-loop control to balance the dc-link capacitors is presented, which provides the capacitor voltage balancing even under dynamic loading conditions without affecting its output voltage. The performance of the proposed converter is analyzed using the analytical and simulation results. Finally, experimental results are presented using the scaled-down prototype to validate the operating principles and performance of HANPC H-bridge converter using the proposed SVM scheme and capacitor voltage balancing control.