Design of the Measurement of the AC Internal Resistance Portable System for Lithium-Ion Battery

• Main Authors: Tzu-Lun Tseng, 曾子倫
• Other Authors: Van-Tsai Liu
• Format: Others
• Language: zh-TW
• Published: 2017
• Online Access: http://ndltd.ncl.edu.tw/handle/s8mcb8

碩士 === 國立虎尾科技大學 === 電機工程系碩士班 === 105 === This paper proposes a portable online measurement system architecture for internal resistance in lithium-ion batteries that uses internal resistance for estimating state of charge (SOC) and state of health (SOH), as well as its application in electric vehicles where dynamic measurement for lithium-ion batteries is required. Based on the electrochemical impedance spectroscopy (EIS), an equivalent circuit model for batteries is used to describe complex chemical reactions inside batteries. Internal impedance in the battery is calculated and obtained by injecting a small sine wave excitation signal into the battery and observing the response signal from the battery. The proposed architecture uses pure AC sine wave excitation signals because of the advantage that pure AC sine wave current is less likely to generate consumption or affect the battery state during measurement. With a micro controller unit (MCU) in combination with purpose-built hardware circuits at all levels and the use of four-wire measurement that prevents wires from affecting measurement signals. Calculation of internal resistance in the battery via the MCU and finally displaying internal resistance and voltage in the battery on the LCD for users to refer to.