Research On The Structure Design And Equalization Technique Based On The Safety Of Electric Vehicle Battery

Heavy pollution and energy shortage in current times have around intense concern about various counties about environment-friendly energy-saving technology. Electric automobiles experienced booming development as a result. However, electric automobiles tend to burn up after crash. People worried a lot about individual differences between batteries, because the batteries exposed to high temperature often encounter spontaneous combustion. Electric automobiles were powered by batteries. Due to low voltage of cells, we need to connect them in series, so as to meet voltage demands of electric automobiles. Batteries are produced in batch and they are different from each other. Limited by current technology, such problem can’t be solved through processing solution. Differences between batteries will be increased in practical use, which may lead to deterioration, soaring temperature, shortening life-span and poorer safety performance, and other problems of batteries.Concerning a series of problems, the thesis researched international and domestic battery safety technologies of electric automobiles and design a three-layer structure which could protect electric automobile batteries in case of crash. Protecting batteries from external crash, this structure can guarantee safety and lower burning risk. In addition, batteries are equipped with temperature equalization structure for cooling. This structure could cool batteries and keep their temperature at a rational level through direct contact, so as to prevent natural burning due to high temperature of batteries. This thesis compared advantages and disadvantages of various equalization circuits and finally adopted the battery equalization circuit based on fly-back transformers. Establishment of equalization circuit could guarantee the two-way balance of batteries and solve the consistency problem of batteries.The thesis first obtained voltage of cells and determined relationships between current and time through charging experiment of cells. This laid s foundation for series connection experiment of batteries. Then, the thesis compared advantages and disadvantages of various equalization circuits through simulation experiment on basis of equalization circuit structure. Afterwards, the thesis completed software and hardware designs for equation system, voltage, temperature, and current measurement.At last, the thesis carried out equalization experiment of lithium ion phosphate batteries by using circuit boards and proved practicality of equalization circuits.