A low-cost approach to on-board electrochemical impedance spectroscopy for a lithium-ion battery: supplementary materials
Description
The folder "Supplementary data" contains the codes used to manage the EIS acquisition and the EIS data obtained in the tests performed in the paper "A low-cost approach to on-board electrochemical impedance spectroscopy for a lithium-ion battery". CODES: 1) The folder Pynq C code contains the C code running on the Pynq Z2 microcontroller with the libraries used to manage two main functions: - to control a custom FPGA layer used to generate a PWM-modulated sinusoidal stimulus signal to inject as a reference signal in the current control loop of a DC/DC converter, which is used as a sinusoidal stimulator for a lithium ion battery; - to control the EVAL-L9963E-MCU board manufactured by STMicroelectronics through an SPI channel to manage the EIS acquisition. The source files could be used to better understand the stimulation/acquisition routine used in the linked paper. 2) In the file "MATLAB main code.txt" there is the MATLAB code used to communicate with the Pynq through a serial interface to download the measurement data acquired by the system. EIS DATA: In this folder you can find some MATLAB data file with the measurements obtained in every test performed in the paper: 1) EIS vs SOC - In this folder you can find some MATLAB data file with the EIS made at 6 different State of Charge (25%, 35%, 45%, 55%, 65%,75%) on a Lithium Cobalt Oxide (LiCoO2) 18650 2600mAh battery manufactured by Alcapower, part code LIR18650HFT. The sinusoidal stimulus signal is generated with a commercial battery charger manufactured by Microchip, part code MCP1630RD-LIC2. It is controlled to generate 100mA peak amplitude sinusoidal stimulus signals in a frequency range from 0.1Hz to 325Hz, with a DC offset of +100mA. The tests are made at an ambient temperature of 24°C+-2°C. 2) Reference RC load test - This folder contains the EIS measurements made on a reference RC load of a 5 Ohm resistor in parallel with a 22uF capacitor used to calibrate the EVAL-L9963E-MCU board. 3) Lithium battery EIS compensation - This folder contains the EIS measurements made with 100mA peak amplitude sinusoidal stimulus signal and zero DC offset, in a frequency range from 0.162Hz to 500Hz, on a Lithium Cobalt Oxide (LiCoO2) 18650 2600mAh battery manufactured by Alcapower, part code LIR18650HFT. The stimulus signal is generated by the Biologc SP200 impedance spectrum analyzer at an ambient temperature of 24°C+-2°C. 4) Reproducibility test - In this folder you can find some MATLAB data file with 90 impedance measurements made with 100mA peak amplitude and zero DC offset sinusoidal stimulus signal at four specific frequencies (1Hz, 10Hz, 100Hz, 500Hz), on a Lithium Cobalt Oxide (LiCoO2) 18650 2600mAh battery manufactured by Alcapower, part code LIR18650HFT. The measurements are made with EVAL-L9963E-MCU battery monitor and the stimulation and reference measurement are performed by an impedance spectrum analyser Biologic SP200.
Files
Steps to reproduce
To work on the data files you can use MATLAB development environment and directly import them in your variable work space. To communicate with the Pynq Z2 and to process data we used MATLAB. To program the Pynq Z2 we used Xilinx Vivado development Environment 2019.1 to design the FPGA layer and Xilinx SDK 2019.1 to program the Pynq microcontroller.