Scalable battery cell cascaded H-bridge converter

Abstract:
Based on cascaded H-bridges at battery cell level, a 132-stage multi-level converter battery system was developed and tested, which has greatly improved properties and functions compared to the state of the art. In addition to the full coverage of the typical battery management functions for the battery cells, the system includes active cell balancing at full operating current and highest inverter efficiencies without additional hardware. With the use of very low-ohmic, low-voltage Si-MOSFET and the low resulting switching frequency of the individual stages, the design can, in a first approximation, be reduced to the consideration of the resistive components in the power path. The low-resistance design of the electromechanical connection between the battery cell and the PCB-based power electronics plays a key role for an efficient battery energy storage system. The presented design shows a very good scalability for current (parallel connection of the power semiconductors) and voltage (series connection of the stages) and thus for power and energy for electrical storage systems.