A Novel Modular Multilevel Converter Based on Interleaved Half-Bridge Submodules

Abstract

A new Modular Multilevel Converter with Interleaved half-bridge Sub-Modules (ISM-MMC) is proposed in this paper. The ISM-MMC exhibits a higher modularity and scalability in terms of current ratings with respect to a conventional MMC, while preserves the typical voltage level adaptiveness. The ISM-MMC brings the known advantages of classical MMC to low-voltage, high-current applications making it a novel candidate for the sector of ultra-fast chargers for all types of electrical vehicles (EV). This advanced topology makes it possible to easily reach charging power of the EV charging system up to 4.5 MW and beyond with low-voltage supply. To operate the new converter, a hybrid modulation scheme that helps to exploit advantages of the interleaving scheme, is implemented, and explained in this paper. It has been verified that the typical MMC control methods are still applicable for ISM-MMC. A comparative study between classical MMC and ISM-MMC configurations in terms of output characteristics and efficiency is also given. Furthermore, it has been demonstrated that the number of ac voltage levels is synthetically multiplied by the number of interleaved halfbridge legs in submodules. Simulations, Hardware-in-the-Loop and Experimental tests are carried out to demonstrate the feasibility of the proposed topology and implemented modulation scheme.

Self-aligned hybrid carrier-based PWM for modular multilevel converters

“…In this paper, the MMCs with parallel cells in SM are considered. [16]. The output voltage of SM (𝑣 𝑠𝑚 ) is the voltage between the common point of the leg currents and the below side of the capacitor.…”

“…In this topology, each SM is constructed by several parallel half-bridge legs (or called . This structure not only allows the total current to be shared across cells to increase quality output [16], but it also ensures the redundancy concept. For that reason, an appropriate modulation method is required to exploit the advantages of this converter.…”