Research And Design Of Lithium-ion Battery Management Unit For Electric Bicycle Based On The Internet Of Things

Electric bicycles were introduced to the market on a large scale earlier than electric vehicles.With their features such as environmental protection,convenience,speed,and reasonable price,electric bicycles have long been recognized by consumers.With the rapid expansion of the scale of the electric bicycle industry and the popularization of its use,the promotion of electric bicycles to China's economic development and green China has received more and more attention.With the rise and development of the sharing economy,shared electric bicycles and shared power batteries have gradually gained consumer favor,and the shared electric bicycle companies and power battery leasing companies behind them also have realistic and unaided equipment Urgent regulatory needs.How to meet the real-time monitoring needs of the battery leasing industry and the location of the battery leasing industry represented by shared power battery companies has become an urgent issue for these companies.Aiming at the problem of remote monitoring and management of power lithium batteries,this paper combines the related technology of the Internet of Things to conduct targeted research and design on the basis of traditional power battery protection boards.The main works are summarized as follows:(1)Analyze some typical equalization circuit topologies,compare the characteristics and applicable objects of various schemes,and design a series switch resistance equalization control unit in combination with the design requirements.Use Saber software to perform hardware circuit simulation on the equalization control unit to verify the effectiveness of the circuit.The simulation results show that the current flowing through the balancing resistor is about 120 m A,which meets the design goals;Then the grouping module passive balancing topology is built based on the balancing control unit to achieve independent balancing between the battery cells or subgroups.(2)Based on the battery terminal voltage as the criterion of equilibrium,a terminal voltage balancing algorithm based on dynamic threshold is designed.The dynamic balancing threshold is to dynamically adjust the battery balancing threshold according to the terminal voltage change curve of the battery in different power stages.In different power stages,the battery balancing threshold is different in size.Aiming at the research on the grouped modular equalization topology and dynamic threshold equalization algorithm,MATLAB / Simulink is used to build an equilibrium model for simulation experiments.During the simulation,the battery pack with inconsistent power is set first,and after balancing,the monitor module is used to observe the voltage of each cell terminal of the battery pack to judge the consistency of the battery pack.The simulation results show that the dynamic threshold equalization algorithm combined with the grouped modular equalization topology reduces "over-equalization" and improves the efficiency of equalization.(3)According to the requirements of remote data transmission,the communication method and data transmission method between the battery management unit and the server side of the monitoring platform are researched.Based on the Internet of Things communication module,the battery management unit terminal and the remote server side are established TCP through the GPRS mobile communication network.Connect and complete the custom protocol data transmission from end to end in the form of TCP transparent transmission.(4)Based on the above design,complete the hardware design of the battery management unit.The hardware circuit includes three parts: power conversion and power balance,information collection and processing,and Internet of Things communication module;Then the battery management unit software design is completed based on the hardware platform.(5)Complete the functional test and performance test of the lithium battery management unit from the aspects of basic circuit,battery information collection,data transmission and positioning,and battery balance.The experimental results show that this targeted balancing threshold adjustment method can effectively avoid the "over-balancing" problem when the terminal voltage is used as the balancing criterion for power balancing.The terminal voltage balancing algorithm based on the dynamic balancing threshold combined with the grouping modular balancing topology has obvious effect on improving the consistency of battery power.Based on GPRS network,in the form of TCP transparent transmission,it can well meet the remote data transmission requirements under the condition of custom protocol.