| Summary: | 碩士 === 輔仁大學 === 電子工程學系 === 91 === Since they were first introduced in the early 1990’s, lithium ion batteries are rapidly becoming the technology of choice for portable computer and cellular phones. With the outstanding features of high specific energy, high energy densities, long cycle life, and 3.6V nominal working voltage, lithium ion batteries have been greatly promising power sources and get into various applications, especially bring in high volume and high power batteries.Most of the battery module applications must connected cells in series providing high voltage power sources, as the sequence, cells will be quite different in internal resistance after many times rugged usage. Lithium ion batteries are sensitive to both over-charge and over-discharge, due to the electrochemical reaction that may occur during abnormal voltage. Therefore, we adopt inevitably battery equalization circuit to balancing cell voltage to prevent the risks of battery string damage, sequentially obtain best battery module energy and extended the battery cycle life.
There are many battery equalization scheme published on the literature, based on different battery type, charging strategy, BMS scheme, and miscellaneous requirement. In this thesis, we classify the famous equalization circuit, also make a summary analysis, and predict the tendency of the large scale lithium-ion battery application.
For the project of lithium ion batteries Electronic Scooter, we study two types of reverse voltage output, non-isolated DC-to-DC converter, analysis the characteristic of bi-directional Bulk-Boost type and Cûk type converter. We designed equalization circuit for high volume lithium ion battery with bi-directional Cûk converter, just because of adjustable continuous current, for high equalizating efficiency；and low EMI character, using ripple free technology, etc.
Via IsPice software simulation, circuit designed review, stability analysis, and Maccor 4000 battery test system examination. From the result, the proposed bi-direction Cûk converter equalization circuit can effectively balance cells voltage during both charge and discharge state. Consequence, it also prolong the calendar life of battery module and guarantee the best module energy.
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