A Hierarchical Modular Equalizer Based on Multi-Winding Transformers
In response to the current issues with battery equalizers in addressing the inconsistency of energy a-mong individual batteries in large-scale series-connected lithium-ion battery energy storage systems,such as slow equalization speed,low equalization efficiency,and weak modularization,a hierarchical modular equalizer based on a multi-winding transformer is proposed by combining a Buck-Boost equalization circuit with a multi-winding transformer equalization circuit.The equalizer adopts a layered parallel equalization mode,and the first-layer equalization adopts a complementary PWM-controlled Buck-Boost equalization circuit with a dead zone,which can effectively avoid energy return,with low energy loss and improved equalization efficiency;the second-layer equalization adopts a multi-winding transformer equalization circuit,which can realize multi-objective equalization at the same time,and optimize the equalization speed.At the same time,the equalizer a-dopts a modular design,which makes the equalizer easy to expand and has a wide range of applications.The structure,working principle and control strategy of the equalizer are analyzed,and a battery system equalization experimental platform composed of 8 single batteries in series is established on this basis.The equalization exper-iment verifies the correctness of the theoretical analysis and the advantages of the equalizer in terms of equaliza-tion speed and equalization efficiency.
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