DC-Side Sensorless Control of Battery Interfaced Three-Phase Full Bridge Cascaded H-Bridge Multilevel Grid-Connected Inverter

Grid connected battery systems play an important role in present day power systems. In this paper, a DC-side sensoreless control of battery interfaced three-phase full bridge cascaded H-bridge multilevel grid-connected inverter is proposed. The key achievement of this paper is the use of the DC-link voltage and current estimation proposed in [1] for a three-phase battery storage system and achieving battery SOC balancing using the estimation algorithm. Coulomb counting (Amp-hour balancing) method is used for SOC estimation because of its simplicity and it can utilize the value of the estimated battery current directly. One disadvantage of this method is the need to identify the value of the initial SOC value which was assumed to be known. The balancing between the batteries has been done using the estimated SOC values. Simulated results are presented to show the efficacy of the proposed algorithm.