Dynamic Equalization Control of Battery Pack Based on Switched Capacitance Method

Abstract

Energy storage technology can greatly promote the smooth supply of electric energy to the grid and facilitate the stability of the power system. However, it is difficult to control the same charging and discharge power of energy storage units with the increasing scale of energy storage power stations. Switched capacitance method is proposed to achieve energy balance between large-scale batteries in this paper, which is easy to implement and more suitable for applications with high power density and energy density. Supercapacitors as energy transfer components are presented to achieve the balance of the high-capacity battery pack. The novel method of parameter selection of supercapacitors, the analysis method of factors that affect the speed of the switched capacitor method are introduced. A two-stage balance main circuit is proposed to simulate the multi-box lithium battery pack’s balance and verify its validity. It is proved that the switched capacitance method proposed in this paper can clearly reflect the battery’s energy state reasonably. Compared with other methods, it has the better compromised performance with small volume, high equalization efficiency and fast equalization speed.