Outstanding Efficiency of a Multilevel CHB-Converter on Battery Cell Level based on LV-Si-MOSFETS

A power electronics platform for battery energy storage systems based on cascaded H-Bridges (CHBs) multilevel topology at single cell level has been developed. A 132s1p battery energy storage system has been implemented on the basis of this platform and is studied with regard to various efficiency aspects in accordance with the Efficiency guideline for PV storage systems. The battery cells used in the system are analyzed separately with regard to (i) their efficiency, (ii) the efficiency trends related to ageing and (iii) different current profiles. It is demonstrated how the inverter efficiency for a system of 132 levels can be derived from the values of the round-trip efficiency (RTE) and the cell efficiencies. The results of these analyses show very promising values for both the system RTE and the derived inverter efficiency.