Design of a cascaded H-bridge multi-level inverter with hot swappable capability for battery energy storage systems

The objective of this paper is to propose a cascaded multi-level inverter for battery energy storage systems. This paper proposes the implementation of the multi-level inverter system having five H-bridge structure inverter modules connected in series with distinct linked batteries. Based on the developed controller, the proposed inverter system can uninterruptedly operate to overcome the disadvantage of power downtime while one of the battery modules is under fault condition or maintenance. By taking advantage of the hot swappable capability, not only the flexibility and fault tolerance of the proposed system can be improved, but the capacity expansion is possible for the battery energy storage systems in microgrids. The control strategy is implemented on a 32-bit floating point TMS320F28335 DSP and tested in standalone mode and grid-connected mode. Finally, the simulations and hardware experimental results from the prototype system are presented to verify the validity of the proposed inverter.