A multi-level converter (MLC) or (multi-level inverter) is a method of generating high-voltage wave-forms from lower-voltage components. MLC origins go back over a hundred years, when in the 1880s, the advantages of DC long-distance transmission became evident.[1]
Modular multi-level converters (MMC) were investigated by Tricoli et al in 2017. Although their viability for electric vehicles (EV) was established, suitable low-cost semiconductors to make this topology competitive are not currently available (as of 2019).[2]
In 1999, Tolbert described the use of MLC for battery operated electric motors.[3]
Habib's 2018 review paper[4] reviews multi-level inverters (a synonym for MLC) stating the advantages of bi-directional energy flows to power the motor or charge the battery system.