Research On Modular Power Supply Of Second Use Power Li-ion Battery For Communication System

With the vigorous development of electric vehicle industry,the recycling and utilization of power Li-ion batteries are facing great pressure,and the communication system has become a good stage of retired power Li-ion batteries due to its working condition and price demand.In this thesis,a modularized power supply for communication system is studied.Based on the second use of retired power Li-ion battery,the research and design of modularized power supply are completed.The stability of the intermediate DC link in the multi-power system is analyzed and verified by simulation and experiment.First,the method of battery second use and the economic benefit of battery second use for peak cut in communication system are analyzed in this thesis.For communication system,considering the inconsistency of retired power Li-ion batteries in the second use process,the whole design of modular power supply is completed.Combined with the design requirements of the power system,the circuit topologies of each module of the system are compared and selected,and the program design of the control system is completed.The MATLAB simulation model and experimental platform of the power supply system are built,and the rationality and feasibility of the control design of the power supply system are verified based on the simulation waveform and experimental waveform.Secondly,the stability of the intermediate DC link of the multi-power system is analyzed.The small signal models of full-bridge DC/DC converter,bi-directional DC/DC converter in Buck mode,Boost mode and Buck-Boost mode are established.The open-loop input and output impedance of the system is analyzed through the small signal model,and the closed-loop input and output impedance of each converter in each mode is analyzed based on the designed control system.Based on the impedance ratio criterion,the open and closed loop stability of the "1+1" cascade system with one full-bridge DC/DC and one bidirectional DC/DC converter is studied,and the influence of inductance and capacitance is analyzed.In addition,the phase-shifting dual-carrier modulation strategy of a dual-mode bi-directional DC/DC converter is proposed.The integrated strategy of charge and discharge of two groups of Li-ion batteries and the control structure of double voltage current double closed loop are proposed.The identification and change method of main and auxiliary Li-ion battery and the matching method of charge and discharge process of main and auxiliary Li-ion battery are proposed.The closed-loop stability analysis of"1+2" cascade system is completed,and the results show that the designed system can run stably.There are 131 figures,12 tables and 78 references in this thesis.