Battery Management Strategy Research And Circuit Implementation Based On Active-passive Hybrid Equilibrium

In the context of the energy crisis and the increasingly serious environmental pollution situation,the promotion of new energy vehicles based on electric vehicles have become one of the effective ways to solve the above problems.Lithium-ion batteries are widely used as power batteries for electric vehicles due to their high energy density,high voltage,and no memory effect.Overcharge and over discharge of single cells can result in reduced or even permanent damage to the available capacity of the series battery pack.This problem seriously affects the life of the battery and has become an obstacle to the development of electric vehicles.At present,balancing battery packs is an effective way to resolve battery pack inconsistencies.Therefore,the paper takes lithium-iron phosphate battery as the research object,aiming to improve the usable capacity and equalization efficiency of the battery pack.It mainly studies the characteristics of the balanced topology and equalization strategy,hardware and software design and experimental analysis.The paper first proposes an equilibrium system with active-passive hybrid equalization as the topology and multivariate fusion as the equilibrium strategy.Among them the active-passive hybrid equalization structure overcomes the disadvantages of passive equalization energy utilization,low equalization current and active control system complexity and high cost.The multivariate fusion equalization strategy introduces a fuzzy control algorithm,so that the equalization system can choose SOC or voltage or SOC and voltage,according to different states of the battery,which overcomes the single variable as the equilibrium strategy cannot be true representation of battery status.Shortcomings.In addition,the implementation process of the multivariate fusion equalization strategy is designed and analyzed in detail,and the optimal equalization current is output according to the actual state of the battery to achieve the balance between the battery cells.Secondly,the hardware and software design is carried out for the battery equalization topology and the equalization strategy of this paper.The hardware selects the host-slave architecture.The host system is mainly for SOC estimation and equalization control.The slave system is centered on the LTC6803 as the center,which is mainly for the collection of battery information.The active equalization selects the flyback transformer as the equalizer,and the passive equalization selects the switch resistor as the equalization.Device.In the software system design process,the modular and hierarchical ideas are used to implement the specific functions of the battery equalization system on the hardware system.Finally,build a battery equalization test platform to test each functional module on the hardware circuit.The main test objects include the sampling accuracy of the battery information in the system,and the function of the fuzzy fuser.Finally,the validity and feasibility of the multi-variable fusion based on fuzzy control proposed in paper.are verified.The experimental results show that the equalization strategy proposed in this paper can achieve equalization under different states and ensure that the maximum voltage difference is less than 0.012 V.The balanced topology and equalization strategy proposed in this paper have balanced efficiency,feasibility and scalability.