Mitigating Common Mode Current in Chain Energy Storage Inverters With Novel Approach

The chain energy storage converter, a type of multilevel converter, exhibits characteristics such as multi-modularization, easy scalability, and low harmonic voltage output, rendering it suitable for medium to high voltage and large capacity energy storage systems. However, the large volume of battery cabinets in large-scale energy storage systems introduces parasitic parameters into the cascaded H-bridge converter, leading to significant common-mode current during switching operations. This paper presents a novel suppression scheme for the chain energy storage inverter's common-mode current. The proposed approach incorporates symmetrical filter inductors and one-dimensional vector modulation to minimize common-mode current and voltage. Simulations conducted in MATLAB/Simulink confirm the effectiveness of the proposed strategy, showcasing substantial reductions in common-mode current and improved compliance with grid specifications.