Modular Multilevel Converter (M2C) system:
Battery cell-based, multilevel converter provide an attractive solution for realizing Medium Voltage Drives as they offer serveral benefits such as: battery cell redundancy, scalability, low fault energy and easy battery cell exchange. These features, and more, put the M2C topology above the available topologies for MV inverters. The M2C technology provides an almost sinusoidal output current that is load and motor friendly making it the best solution for numerous applications. The M2C topology as used for medium voltage drives connects several low battery voltage cells into series to produce a medium voltage output voltage.
In the simplest case, the power cell consists of two IGBTs and one capacitor (or capacitor bank). Such power cells are also called “single submodules” whereas the “double submodule” or “twin submodule” consists of four IGBTs and two capacitors. Due to its common dc link, the M2C topology allows using state of the art diode front ends as well as integration of braking chopper for dynamic braking operation. Unlike as with other battery cell based topologies, the number of battery cells on the motor side is independent of the selection of the line side pulse number. This allows not only adjusting the pulse number to the drive system requirements but also improves the system reliability as standard converter transformers can be used.