| Summary: | 碩士 === 國立高雄應用科技大學 === 應用工程科學研究所 === 101 === In recent years, rechargeable batteries are developed from the very beginning Lead-Acid battery to the higher energy-density Li-Ion battery or Li-Polymer battery. The increased energy density escalates battery capacity, and applications of rechargeable batteries also become more popular and widespread. However, in battery applications, series-connected batteries still need to be connected by quantity to reach certain voltages required by the devices. Furthermore, due to the difference from individual battery among series-connected batteries, it leads to an unbalancing voltage existed between batteries, causes some series-connected batteries over-charged or over-discharged, influences the efficiency of series-connected batteries, shortens the battery life of series-connected batteries and even results in battery expansion or burning during the application of series-connected batteries. Therefore, the research of voltage balancing for series-connected batteries is nowadays a very important task.
This research is to offer a circuit structure automatically balances the voltage difference between batteries. Under the basis of switched capacitor balancing structure, it is applied programmable logic controller (PLC) to substitute for the pulse generator from the original structure, to monitor single battery voltage, to switch ON/OFF through PLC command, to make battery energy from the higher-voltage battery transfer into the balanced capacitor first and transfer the battery energy to the lower-voltage battery later through switching ON/OFF. It is also expected to reach voltage balance of series-connected batteries through this circuit structure.
The experiment based on this research is to use 1C, 1.5C and 2C respectively for charging and discharging, and to compare the voltage difference from batteries with or without voltage balancing circuit. The result shows the average voltage difference value will be at most 30.7% lower.
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