State of Charge Equalization of Battery Modules Using Single-Phase Cascaded Multilevel Converters

This paper aims to use cascaded multilevel converters for connecting several battery modules to a single-phase AC grid or load. Electrical power is exchanged either from storage to AC side to discharge battery modules, or from AC side to the storage to charge battery modules. Charging and discharging operations are performed while battery modules' state of charges get equalized. AC side current is also controlled to follow its reference while high differential-mode dv/dt on load are avoided using adjacent voltage levels assignment. For these purposes, no additional controlling circuit is implemented and only one controlling block is defined to handle AC current reference tracking, and state of charge balancing tasks. Model predictive control, as a technique capable of multi-parameter controlling, is used to achieve beforementioned system objectives in a simple, efficient, and scalable manner. MATLAB Simulink simulations demonstrate the feasibility of proposed controlling strategy for this sort of application.