Voltage Equalization of Series Energy Storage Unit Based on LC Resonant Circuit

Abstract

In energy storage systems, multiple energy storage monomers are usually connected in series to obtain higher voltages, but the inconsistency of the voltage of each energy storage monomer will reduce the utilization of the storage unit. To address this problem, this article proposes a method for equalizing the voltage of series energy storage units based on LC resonant circuit. The equalization circuit consists of a switch array and an LC resonant converter, which can achieve energy transfer between any monomer and continuous multi‐monomer, and realize zero‐current conduction of the switch. The equalization circuit does not have a large number of magnetic components, and for each additional energy storage monomer, the circuit only needs to add a pair of switches, which has the advantages of high flexibility and expandability. Finally, the equalization simulation experiments are conducted on the Matlab/Simulink platform for the energy storage unit composed of four series‐connected energy storage monomers. The experimental results show that under static equalization, the voltage reaches equalization in about 25 min and the equalization efficiency reaches 96.64%, which greatly reduces the switching loss, improves the equalization speed and efficiency, and verifies the feasibility and effectiveness of the method.