Design And Study On Carbon Coated Aluminum Nanoparticles/Paraffin Wax Phase Change Composite And Battery Management System

Under the threat of energy shortage and environment pollution, every country is trying to look for new substituted green energy in new era. In many energy-consuming applications, traffic transportation cost most energy and cause heavy environment pollution. Therefore, In new energy industry, more and more study focuses on electric vehicle in recent year. However, the development of electric vehicle relies on its power supply-battery. Since lithium battery carries excellent characteristics, such as light weight, small volume, high energy density, good cycling performance and so on, lithium battery vehicle is the perfect power supply for Electric Vehicles. Nevertheless, the performance of lithium battery used by electric is limited by many factors. The major affecting factors include working temperature, discharge and charge voltage, working current and battery capacity. Therefore, in order to ensure lithium battery working at optimized state, it’s necessary to build up battery control and management. This study prepared carbon-coated aluminum(Al@C) nanoparticles by using direct current arc discharge method, and filled Al@C nanoparticles into paraffin wax (PW) matrix to prepared carbon-coated aluminum/paraffin wax (Al@C/PW) phase change composite, then applied Al@C/PW composite into battery management system as cooling medium and studied its thermal characteristic and cooling performance. And according to the working requirement of lithium battery, this study designed a battery management system which can manage a 6-series battery module, it could monitor and control battery module. The main points are summarized as follows:(1) We prepared Al@C nanoparticles by direct-current discharge method, and investigated its crystal structure, morphology, mircosturcture and its thermal characteristics by using X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscope (TEM), thermogravimetric (TG) and differential scanning calorimeter (DSC) analysis. And we filled Al@C nanoparticles into paraffin wax to prepare Al@C/PW phase change composite and studied its thermal characteristics, thermal stability and conductive performance by DSC, TG and laser flash method. Al@C/PW composite was aoolied as lithium battery cooling material, and its cooling effect on lithium battery series was tested in battery discharge experiment. Results show that Al@C nanopartilces are spherical particles with core-shell structure. It can be added into paraffin and prepare Al@C/PW composite. Comparing to pure paraffin, the thermal stability and conductive performance of Al@C/PW composite are significantly improved. In the battery discharge test, the cooling speed of system using Al@C/PW composite as cooling medium is fastest, and control the batteries surface temperature effectly.(2) According to the working requirement of lithium battery, a battery management system was designed, which can control a 6-series battery module. The designed system includes functions such as battery voltage monitoring, batteries balancing, SoC evaluation, working current monitoring and battery protect. According to these functions, the whole system can be divided into five basic functional modules, and we develop all the circuit schematics and PCB layouts based on five functional modules design. The whole printed circuit board (PCB) was prepared and debugged based on the designed circuit schematics and PCB layouts.(3) Driver program of every module and user interface software were developed. According to the working process of every module, the initialization program and interruption program of every module was developed as well as the serial peripheral interface (SPI) and inter-intergrated circuit (I2C) transmission initialization program. According to the required system function, the menu and the settings of the user interface software were designed and developed, and the actual function of BMS was tested in battery charge/discharge test. Results show that the system generally finished the data-collecting tasks successfully and meet the design requirement of BMS.