| Title |
A Portable Impedance Spectroscopy Instrument for the Measurement of the Impedance Spectrum of High Voltage Battery Pack |
| Authors |
힘Gul Rahim ; Woo-Jin Choi |
| DOI |
10.6113/TKPE.2021.26.3.192 |
| Keywords |
High voltage battery pack; EIS (Electrochemical Impedance Spectroscopy); AC impedance spectrum; DLA (Digital Lock-in Amplifier); ARM cortex-M4 microcontroller |
| Abstract |
The battery’s State of Health (SOH) is a critical parameter in the process of battery use, as it represents the Remaining Useful Life (RUL) of the battery. Electrochemical Impedance Spectroscopy (EIS) is a widely used technique in observing the state of the battery. The measured impedance at certain frequencies can be used to evaluate the state of the battery, as it is intimately tied to the underlying chemical reactions. In this work, a low-cost portable EIS instrument is developed on the basis of the ARM Cortex-M4 Microcontroller Unit (MCU) for measuring the impedance spectrum of Li-ion battery packs. The MCU uses a built-in DAC module to generate the sinusoidal sweep perturbation signal. Moreover, it performs the dual-channel acquisition of voltage and current signals, calculates impedance using a Digital Lock-in Amplifier (DLA), and transmits the result to a PC. By using LabVIEW, an interface was developed with the real-time display of the EIS information. The developed instrument was suitable for measuring the impedance spectrum of the battery pack up to 1000 V. The measurement frequency range of the instrument was from 1 hz to 1 Khz. Then, to prove the performance of the developed system, the impedance of a Samsung SM3 battery pack and a Bexel pouch module were measured and compared with those obtained by the commercial instrument. |