Electric Car Lithium-ion Battery Management System Research And Design

With the continuous development of auto industry,the number of cars in the world grows very fast,the problem of the energy and the environment is more and more serious.In order to alleviate the pressure of energy and environmental pollution,all countries consider electric vehicles as the substitute for conventional cars.As the future direction of development,electric vehicles have been paid more and more attention.But the problems which restrict the development of the electric car are still the battery storage and application technology.How to prolong the service life of the battery,improve the energy efficiency of the battery and reliability,is the problem that industrialization of election vehicles must be solved,so the research of battery management technology and the system has very important significance.Electric vehicles would make the batteries in series with groups in order to obtain sufficient electricity.Due to the process of production of monomer battery,each monomer battery has differences in capacity and performance,and with the increase of cycles of battery charge and discharge,these differences will expand,then will accelerate the damage of the battery.So power battery needs the equalization circuit to extend the life of batteries.This paper studied the balance management system of the electric vehicles and designed an reasonable balance management method and carried out the simulation verification.This paper including the following work:First,this paper analyzed the influence factor of the working performance of the lithium-ion batteries,presented the modeling method of lithium battery.Based on the working characteristics of lithium battery and the battery management system,analyzed the architecture of the common lithium battery management system,introducing the realizing way of the partial function of lithium-ion battery management system.And analyzed the cause of the affect that in the lithium battery SOC and the consistency of lithium battery.Then,due to the problem that current balance control of lithium batteries are controlled by the battery management system and can’t use independently,this paper designed the rechargeable battery equalization protection method.This design has applied for national invention patent（Application Number: 201610108649.4）.This method is different from embedded battery management system,and makes the simple simulation electronic voltage detection unit directly connected to the battery.The voltage comparison is made by its own reference voltage and battery voltage comparator.The charging,balancing and discharging is controlled by outputting high and low level.At last,this paper used the Multisim to make the simulation of the design,and made the circuit board to do the performance testing.The simulation results and performance test showed that,the balanced protection method can accomplished the control of charging control and balanced protection accurately in the charging process,and can give the warning during the over discharge.Now this design is working with the enterprise to make product.