Research Of Technologies Of Pure Electric Vehicle Battery Pack

As technology advances and the energy crisis, car manufacturers are working on new energy vehicles now, our country even treat new energy vehicles as a national strategy. As one of the most important new energy vehicles, pure electric vehicles (PEV) have low noise, low pollution, simple structure and other advantages. Battery pack is one of the key technologies of pure electric vehicles, Outstanding battery pack has many characteristics such as excellent energy density, stable electrical performance and good temperature consistency. The research object of this paper is commercial ternary polymer lithium-ion battery used to PEV.The principal results are as follows:1. The structure of battery cell is analyzed, the voltage-capacity curve and the resistance-capacity curve of the battery characteristics are obtained by experiment. Thermal model of single battery is established and carried out temperature rise experiment with different current in insulation and nature cooling. The influence of the pressing force of the battery cell is analyzed and find out the best pressing force by cycling experiment.2. Based on the characteristics of the battery cell, The first packing-scheme is designed by using pressing way to fix the mechanical structure and circuit configuration and trial manufacture of module. Discharge performance of the battery modules, temperature distribution in different current, ability of anti-vibration are measured by experiment. The advantages, disadvantages and feasibility of the scheme is analyzed.3. Referring to the first packing-scheme and the test results, A new scheme is designed by using pressing way to fix the mechanical structure and welding to circuit configuration. The second scheme is better at battery life, reliability of the electrical connection and consistency of temperature and the experiment also prove it.4. The vehicle module is established by using Matlab/Simulink software platform. The module parameters are based on second packing-scheme and a commercial vehicle. Using the model, the uniform speed conditions, urban condition and extreme conditions of pure electric vehicles are simulated. The highest speed,0-100km/h acceleration time, battery temperature and other data are received. The result prove that under normal temperature, normal driving process does not require forced cooling measures. When PEV used in extreme conditions, battery temperature may appeared to damage battery life. The paper proposed a control strategy that limited motor output power to achieve the limited temperature of the battery.