A Study on Battery Charge Equalization Circuit with Multi-Winding Transformer

• Main Authors: Yi-Hsiung Fang, 方毅雄
• Other Authors: none
• Format: Others
• Language: zh-TW
• Published: 2013
• Online Access: http://ndltd.ncl.edu.tw/handle/14948544178144909456

碩士 === 國立雲林科技大學 === 電機工程系碩士班 === 101 === Due to the LiFePO4 batteries contain not only the advantages of the Lithium batteries, but also have large current discharging characteristics, higher cycle life and better security. Over-charging (over-discharging) phenomenon will not occur as long as the terminal voltage of battery is strictly controlled. Therefore, LiFePO4 battery pack is suitable to apply for power sources of electric vehicles. This thesis proposes a battery charge equalization circuit with multi-winding transformer. Full-bridge converter with soft-switching is applied in primary-side of the multi-winding transformer for reducing switching losses and increasing the efficiency of the proposed circuit. A voltage doubler type rectifier is used in secondary-side of the multi-winding transformer for decreasing the amount of transformer windings and conduction losses of the rectifier. The proposed circuit has a crucial advantage that no choke inductor in the circuit due to charge current is all limited by the leakage inductance of the transformer and charge equalization is realized by adjusting the turn ratio of transformer. In experiments, four LiFePO4 battery modules (12.8 V/12 Ah) are series connected and discharged with different C-rates. The experimental results show that the discharging time of series-connected battery modules can be increased obviously by the proposed battery charge equalization circuit.