Research On Battery Equalization For Electric Vehicle

With the increasing environmental pollution and energy crisis, electric car become more andmore valued with its diversified energy sources and will be the mainstream direction of futureautomobile industry. Battery management system is one of the three key technologies of electric cars,it plays an important role on energy efficiency and battery life of electric cars and the batteryequalization technology is one of the core technologies of battery management system. This paperfocuses on the electric vehicle battery equalization technology and the main contents are as follows.Firstly, the paper makes a deep research on the performance of all kinds of power batteryaccording to the literature from home and abroad, and selects the power battery type, and analyzecharge-and-discharge characteristics of lithium iron phosphate battery, and lay a theoreticalfoundation for the establishment of equilibrium strategies.Secondly, the paper formulates the overall scheme of balance system hardware circuit anddesigns the optocoupler gating circuit, voltage sampling circuit, switch driving circuit andequalization circuit.Thirdly, the paper makes the equilibrium strategies of grouping module, and writes software unitlike initialization module, data acquisition module, CAN communication module and balanced controlmodule in the system by using C language.Finally, the paper verifies the reliability of voltage acquisition circuit by experiment, and makesrelated experiments about balanced system, and studies the effects of different duty ratio D on theequilibrium speed after verifying the effectiveness of the equilibrium system.