Advanced Automotive System based on Modular Multilevel Converter
Battery packs in recent electric vehicles (EVs) have high energy and high power densities which exerts a strong thermal stress upon them. This means that the individual battery cells are more prone to decline away and eventually fail early because of an excessive loss of capacity and an increase of internal resistance caused by accelerated aging. Moreover, for electromechanical reasons, each cell is totally unbalanced in operating mode. Unfortunately, most of the published literatures are carelessly emphasizing the fault ride-through capabilities of actual automotive battery packs. Therefore, for safety, efficiency and flexibility reasons, this presentation proposes a new concept for packaging EVs battery based on Configurable Modular Multilevel Converter (CMMC). In addition, EVs owners are confronted by the limited compatibility of available charging infrastructures. Hence, the CMMC is designed for a large range of charging infrastructure; from AC household basic supply to AC or DC ultrafast charging infrastructure. The CMMC proposes an intelligent control for power quality in EV application. The concept is proposed for universal and flexible EV charger and it is based on the MMC. It aims to use the existing motor winding as current filter during charging mode and the traction converter like charger converter. It distributes also the conventional battery pack into multilevel module, which increases the fault ride-through capabilities of the EV battery against thermal runaway. The electrical motor is fed by multilevel voltages which also increases the motor efficiency. In fact, the switching mode is controlled by a shifted angle between the upper-arm and lower-arm currents. This new concept allows interfacing EV to worldwide charging infrastructure which increases the flexibility of EV owner.