Search

With the widespread application of lithium-ion battery packs, it calls for efficient balancing methods to improve the performance of these battery systems. The relevant research has focused on the design of equalization circuits and control strategies while neglecting quantitative analysis and comparison of battery active equalization structures from the systematic level. In this paper, we propose an improved system-theoretic modeling approach for active equalization structures that takes into account the battery's constraints, including equalization current rate and SOC operation range. Accordingly, the mathematical models of various active equalization structures are derived that can describe their equalization dynamic behavior. Then, the analytical algorithms are developed to estimate the balancing time of active equalization structures online. Finally, extensive numerical simulations are conducted to evaluate and compare the average performance of these equalization systems in term of equalization time. It then comes up with a comprehensive comparison among them. Consequently, the Multicell-to-Multicell (MC2MC) balancing structure benefits the fast balancing speed and the lowest sensitive to initial batteries’ SOCs. The global structure has the lowest implementation cost and the series structure benefits the simplest control. Moreover, the module-based structures have faster balancing speed when each module contains about 4–6 batteries. [ABSTRACT FROM AUTHOR]

In order to realize power flow control among photovoltaic (PV) panel port, battery port, and load port in the distributed photovoltaic power generation system, integrated three-port dc–dc converters (TPCs) are widely adopted. The objective of this article is to provide a comprehensive, comparative, and insightful analysis and overview of these TPCs. First, based on the power transmission and control requirements of the system, five topological structures of three-port dc–dc conversion system (TPCS) composed of two or three two-port dc–dc converters are presented. And the five structures are comparatively analyzed. Second, based on these topological structures, and combing with the basic two-port dc–dc converters, three groups of typical TPCs with different galvanic isolation requirements are derived, respectively, by sharing switches, combining branches, etc., And comprehensive analysis, comparisons, and reviews of these TPCs with different structures of each isolation type are presented with tables and figures. Finally, the comparison results of the three isolation groups are summarized, which leads to a guidance for the selection of TPCs in different applications, and then some suggestions for the future research on TPCs are given. [ABSTRACT FROM AUTHOR]