Reasearch On Active Equalization Technology Of Battery Pack Based On Bidirectional Flyback Converter

As the energy crisis and environmental problems continue to intensify,energy storage technology,as an effective way to consume clean energy,plays an important role in many fields.In rail transportation,aerospace and other fields,battery packs of various voltage levels can be used as energy systems.Due to the influence of battery factory parameters,working environment and other factors,there is inconsistency between the batteries,which reduces the usable capacity and cycle life of the battery pack and seriously affects the use of the battery pack.This thesis proposes a equalization system solution based on bidirectional flyback converter for battery inconsistency.First of all,this thesis analyzes the working principle of the bidirectional flyback converter and derives the formula,explaining its difference from the unidirectional flyback converter.Different control methods are introduced.The voltage and current stresses of the flyback converter are analyzed and compared.The suggestions of circuit parameter design are given.For the energy of leakage inductance and part of magnetizing inductance in the transformer,the working principle of RCD absorption circuit is analyzed,and the relationship between the overvoltage of the switch tube and the absorption parameter is analyzed from a power perspective,and the design formula of the absorption circuit parameter is derived.By building a simulation model,the principle of bidirectional flyback converter and absorption circuit is verified.Secondly,the battery active equalization system based on the bidirectional flyback converter is introduced,which mainly includes a modular-based equalization system and a switching array-based equalization system.The structure and working principle of the equalization system are analyzed separately.According to different application scenarios,different structures of equalization system can be adopted,which increases the practicality and versatility of the equalization system.Thirdly,by analyzing the battery inconsistency,the equalization control strategy based on battery voltage,state of charge and switch array is introduced.In order to verify its feasibility,a simulation platform was built to verify and analyze several equalization control strategies.The simulation results all proved the effectiveness and feasibility of the equilibrium control strategy.Finally,based on the above principle analysis,the hardware and software of the equalization system are designed,and a hardware experiment platform is built.Combined with software control,the working principle,equalization control strategy and battery balancing effect of each part of the equalization system are verified,and the equalization control between the batteries can be realized...