A Novel Dynamic Performance Analysis and Evaluation Model of Series-Parallel Connected Battery Pack for Electric Vehicles

Due to the low voltage and small capacity of a Li-ion battery cell, large numbers of cells are connected to construct a battery pack to satisfy the voltage and capacity requirement of the power system of an electric vehicle. Focusing on parallel and series connection mode of battery packs, the main contributions include the following. First, in order to increase the utilization rate of cells and enhance the performance of the battery pack, a method that makes the battery pack achieve their maximum initial capacity has been proposed. Second, a dynamic modeling and analysis method for the battery pack based on the equivalent circuit model has also been proposed. The results show that the battery pack in parallel and then in series has a better performance on charge/discharge capacity, efficiency, and utilization rate of cells. Third, the performance analysis and evaluation platform of the battery pack has been built, and the battery pack test results of different groups supported the conclusion of the simulation. The battery packs in parallel and then in series can achieve superior performance and greatly increase capacity and energy utilization.