Control of Active Power Exchange With Auxiliary Power Loop in a Single-Phase Cascaded Multilevel Converter-Based Energy Storage System

Cascaded multilevel converter (CMC)-based energy storage system, which consists of cascaded H-bridge converters and energy storage components, is a promising option to compensate fluctuating electric power of renewable energy. This paper proposes a novel single-phase CMC-based battery storage system, which includes an
LC
branch. The cascaded converter cells and the
LC
branch form an auxiliary power loop, which could realize active power exchange between different cells with the proposed dual-frequency phase-shifted carrier pulse width modulation (DF-PSC PWM). The principle and effectiveness of DF-PSC PWM and the power transfer mechanism are analyzed. Meanwhile, the design of the tuned filter, output filter, and the state of charge balancing control system is introduced. The operation principle of the power exchange in the proposed energy storage system has been successfully verified by simulation and experimental results.