Development of a Remaining Capacity Estimation System for Lithium-ion Batteries

• Main Authors: CHUN-TA CHEN, 陳俊達
• Other Authors: Yi-Hua Liu
• Format: Others
• Language: zh-TW
• Published: 2012
• Online Access: http://ndltd.ncl.edu.tw/handle/40237329394199821563

碩士 === 國立臺灣科技大學 === 電機工程系 === 100 === Nowadays, the number of portable consumer electronics such as mobile phones and laptop computers has grown rapidly. These developments have resulted in massive demand for batteries. Secondary batteries are often used in these devices because they are cost-effective over the lifetime of the product. For secondary batteries, lithium-ion (Li-ion) batteries are the most popular type of battery for portable electronics, due to their high energy-to-weight (volume) ratios, no memory effect and high open circuit voltage. Li-ion battery requires monitoring system that is capable of measuring the parameters (voltage, current and temperature) of individual cell in order to prevent damage and identify defective cell. In addition, knowing the amount of energy left in a battery compared with the energy it had when it was full gives the user an indication of how much longer a battery will continue to perform before it needs recharging; therefore, the battery state of charge (SOC) information is essential. However, measuring the battery SOC is not an easy task because the SOC depends on many factors such as temperature, battery capacitance and battery internal resistance. The main objective of this thesis is to estimate the state of charge of the Li-ion battery accurately and effectively. In this thesis, a battery monitoring system for Li-ion cells is proposed. The presented BMS provides the following features: accurate measurement of battery parameters including charging/discharging current, cell voltages and cell temperatures and information of SOC. It also provides battery over voltage, battery overcharge/over discharge and battery over temperature protection. The presented BMS can communicate with an external host using UART/USB communication protocols. In this thesis, the central controller utilized is STM32 microcontroller from STMicroelectronics Corp. In order to provide the real-time display and data logging of the battery parameters, a user-friendly graphical user interface (GUI) is also developed using Borland C++ Builder. Detailed description of the hardware and software of the proposed BMS will be provided, and experimental results will also be provided to verify the correctness of the proposed BMS.