Common Mode Analysis and Suppression of Chained Energy Storage Systems

The chain energy storage system has the structural characteristics suitable for use in large-capacity battery energy storage systems, but the energy storage battery is large in size, and it introduces certain parasitic parameters in the chain energy storage system, which will lead to the inverter in the switching tube high-frequency turn-on and turn-off process, generating a large common-mode current, which will damage the life of the power devices and jeopardize the stable operation of the system equipment. Firstly, a simplified model of chain energy storage system is established to analyze the common mode voltage intrusion into the battery system pathway of the chain energy storage system. The characteristics and influencing factors of the common-mode current of single inductor circuit and symmetric inductor circuit are studied separately, and it is pointed out that the common-mode current of the symmetric inductor circuit can be effectively suppressed by optimizing the modulation strategy. To this end, an improved one-dimensional modulation strategy is proposed for the symmetric inductor circuit and the power tube switching state, which can effectively suppress the system common mode current. Finally, the correctness of the analysis is verified by simulation experiments.