The Research Of Active Balanced Electric Bike Lithium-ion Battery Intelligent Protector

Electric bicycles are widely used in most families. Although in 2015 the sales of electric bikes dropped to 29.5 million compared with 35 million in 2014, the sales of electric bicycles with lithium battery reached 4.5 million to 5 million, which benefited from favorable policies and declining cost of lithium batteries. In next three years, lithium bike will maintain an average annual growth rate of 40%, and will reach 12 million by 2017. Meanwhile, the lithium penetration will reach 30%. Therefore, it is particularly important to make a study on related technologies of lithium batteries for electric bicycles in a period of time in the future.Lithium battery protector has become an indispensable part of electric bicycle lithium batteries. This thesis puts forward a balanced active electric bicycle lithium battery intelligent protector, completing 13 string 48 V lithium battery overcharge protection, over-discharge protection and active balance. This thesis presents a balanced active lithium battery protector used in electric bicycle. It aims at solving the problem of taking power a single lithium battery pack and the monomer SOC inconsistency in the process of charging and discharging, which cannot be resolved well with passive equalizer type lithium battery protector. In this thesis, an active equalization algorithm based on outliers is proposed. It can increase the voltage acquisition precision of lithium battery cells by establishing a model for voltage outliers, reducing the risk of signal interference when lithium battery protector collects the voltage of the lithium battery monomer. This algorithm can effectively reduce the risk of the monomer SOC inconsistencies caused by balancing strategy. Combining with intelligent protector function, it is easy for lithium battery protector to check the health status of the lithium battery monomer and make a pre-judgment with a programmable control functions and CAN communication transceiver functions.In summary, the thesis proposes a balanced active and intelligent protector for electric bicycle lithium battery, creative solutions for single cell lithium battery electric bicycle take power problems, which aims at resolving inconsistent state of charge on electric bicycle lithium battery, and increasing the battery voltage sampling accuracy, improving the accuracy of balanced lithium battery protector. In this thesis, we use DCDC active equalization circuit, to achieve the maximum balanced current to 194 mA. In addition, the use of CAN communication can realize intelligent application of lithiumion battery protector. This topic puts forward the active balanced electric bicycle lithium battery intelligent protector, which can improve conversion efficiency of the lithium-ion batteries power and prolong the service life of lithium-ion batteries.