Electric vehicle battery equalization technology applied to vehicle-to-grid

Abstract

Electric vehicles (EVs) do not rely on oil and are in line with the low-carbon concept; vehicle-to-grid (V2G) technology can quickly and flexibly dispatch the energy storage of EVs, which has an extensive development prospect. Automotive battery equalization technology can allow many series-connected lithium-ion batteries in EVs to be fully charged and discharged simultaneously, significantly improving the battery pack's available capacity and operational safety. Considering the actual needs of EVs, the optimized buck-boost-based equalization circuit is proposed, which has the advantages of simplicity, small size, and high reliability. Meanwhile, this article presents the optimized voltage-based equalization control strategy, which has the advantages of convenient control and is easy to implement. It analyzes in detail the working principle of the proposed equalization technology and its applicability to EVs. A test platform is built for testing, and the results show that the consistency of battery cells in the battery pack is significantly improved under three working conditions: resting, charging, and discharging. The experimental results prove the feasibility of the proposed strategy.