A novel power balance control scheme for cascaded H-bridge multilevel converters with battery energy storage

Abstract

Battery energy stored quasi-Z source cascaded H-bridge based photovoltaic power generation system combines advantages of quasi-z-source inverter, cascaded H-bridge, and battery energy storage system. However, the battery state of charge imbalance between the cascaded H-bridge inverter modules would reduce the system's performance and efficiency and potentially cause the system to fail. An integrated control technique of adaptive state of charge balancing based on gain scheduling and three-phase power balance of third harmonic injection based on fundamental frequency whole zero sequences is suggested for the quasi-Z source cascaded H-bridge battery storage system. Based on the mathematical relationship between the instantaneous state of charge of battery energy stored quasi-z-source cascaded H-bridge and the voltage reference value, this method updates the proportional controller gain in each sampling period. It combines the third harmonic injection method based on the fundamental frequency zero sequence to select the optimal modulation ratio Mn. Rapid state of charge balancing is accomplished without overmodulation while increasing the power balance range and decreasing DC link voltage swings. The simulation results validate the method's usefulness. The simulation results validate the proposed control method for ensuring power distribution between each phase and achieving a balanced state of charge of the battery energy stored quasi-Z source cascaded H-bridge photovoltaic system's battery energy storage.