A Review on Modular Multilevel Converters in Electric Vehicles

This paper discusses the state of the art of different topologies of Modular Multilevel Converters (MMC) used in Electric Vehicle (EV) power-train. A comparative study of recently proposed MMC used as a propulsion application in EV is elaborated here for the first time in EV research field. First, this paper delivers a general overview on multilevel converters associated with their various types and advancements. Then, it discusses the change from Internal Combustion Engine Vehicle (ICEV) to EV. Finally, it conducts a comparative study on the existed MMC topologies by categorizing them into five sections according to their types and contribution. First section includes the topologies that follow the same MMC architecture of cascaded half bridges. Second section discuses topologies consisting of cascaded H-bridge (CHB) and points any recorded contribution in comparison with conventional topologies. Third section focuses on topologies that reduces switching elements significantly making the whole system more reliable, cost competitive, more efficient and more size compressed. Fourth section tackles topologies with hybridized energy storage system using Ultra-Capacitors (UC) in order to track its impact on power density limitation. Last section adopts hybridized multilevel converters to observe its effect on system's efficiency and switching losses. The contribution of this paper is pointing on the strength and weakness of each topology in terms of fault tolerance, balance control, size, reliability, efficiency, cost, power density, mobility range, switching elements and switching losses.