Battery charge equalization circuit with a multi-winding transformer

摘要

This study proposes a battery charge equalization circuit with a multi-winding transformer. A full-bridge converter with soft switching is applied at the primary side of a multi-winding transformer for reducing the switching loss and increasing the system efficiency. A voltage doubler type rectifier is used at the secondary side of multi-winding transformer to decrease the number of transformer windings and the conduction loss. The important advantages of the proposed circuit include the following: The charge current is limited by the transformer leakage inductance without any choke inductor, and charge equalization is realized by adjusting the transformer's turn ratio. A measurement index, charge equalization performance (C.E.P.), is introduced for the performance measurement of the charge equalization method. In experiments, four LiFePO4 battery modules are connected in series and discharged at different C-rates. The experimental results show that the discharging time of the series-connected battery modules can be greatly increased using the proposed battery charge equalization circuit.