| Summary: | 碩士 === 國立臺灣科技大學 === 電子工程系 === 102 === The market of electronic products changes so fast that batteries play an important role in the related area nowadays. One of the major rechargeable batteries is Lithium-ion battery, which features high energy capacity, high power density, long lifetime, and no memory effect. Lithium-ion batteries are connected in series to satisfy the high voltage demand. However, because of the mismatches in the manufacturing process, it may occur an imbalance problem among the batteries during the charging period. Therefore, a balance charger to maintain the normal operation of batteries is required for a battery management system (BMS).
This thesis aims to design a Lithium-ion battery charger which can be used in a BMS. To achieve this target, a quasi-resonant flyback DC/DC converter with secondary synchronous rectification to effectively reduce the loss and improve the converter efficiency is studied and designed. Finally a 22.5-W laboratory prototype is implemented and verified with theoretical analysis and simulations. The input voltage range is from 38 V to 65 V, and the output voltage is 4.5 V. A charging strategy with two-stage constant-current charging and one-stage constant-voltage charging is adopted. The efficiency achieves 86% at low input and full load condition.
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