Research On Battery Management And Energy Recovery System Of Regenerative Braking For Agricultural Tricycle

Fossil fuel shortage and environmental pollution are becoming more serious problems,which make contribution to the the development of agricultural tricycle(AT).In consideration of the relatively low economic affordability of rural areas,lead-acid batteries was used in AT for the advantage with low cost and good stability performance.For lack of system management,it will lead to easy to be damaged in the use course of lead-acid batteries of AT.In addition,low capacity is still the biggest obstacles when the long-term work of AT was needed.Therefore,this paper focus on lead-acid battery management system and regenerative braking energy recovery about the AT under the premise of lead-acid battery as major research object.The following is the main work and results:The charge-discharge management of battery,estimation of state of charge(SOC)and state of health(SOH)are the focus of research in the battery management system of AT.In this paper,an intelligent multi-stage constant voltage and limiting current method is proposed,which is different from the traditional lead-acid battery charged by constant voltage or constant current method in the battery management system.Under ensuring the sureness of efficiency in the process of charging,the intelligent charging module is used to take charging in lead-acid battery of AT.In the process of discharging of lead-acid battery,the threshold voltage is set to avoid over-discharging.In the research of SOC estimation,firstly,according to the SOC algorithm and Thevenin equivalent circuit model of lead-acid battery,then a HPPC test was carried out based on equivalent circuit model of the battery,in order to fit out the mathematical function relationship between model parameters and the battery SOC,the corresponding calculation formula is used for the model identification,such as open circuit voltage,polarization resistance,resistance,polarization capacitance and other parameters of battery.Secondly,through two different experimental conditions simulation,the model of battery with high accuracy was verified.Finally,simulation worked in MATLAB operating environment and experimental results show that,the estimation model of SOC based on extended kalman filter(EKF)principle has the advantages of high accuracy and adaptability.In addition,a least squares method is used when the SOH of the battery is estimated,which fits the partial discharge curve aswell as assesses the battery performance and remaining life by obtaining the first-order coefficient.The regenerative braking energy recovery of AT is necessary in order to recycle the battery power.The contents of the braking energy recovery research include: the mathematical model of AT is established,which based on the mathematical model of permanent magnet DC motor and the equation of motion when the AT are driven.A velocity-current double closed-loop control system was devised for the AT to control driving and braking.In the process of braking,the energy was recovered by controlling the two quadrant DC/DC chopper circuit with a constant braking torque control method and a RBF neural network are taken as control algorithms.Under the MATLAB operating environment,the results in different experimental conditions show the regenerative braking energy of AT can be effectively recovered after building the entire AT model with structures of ADVISOR,especially on the long downhill braking condition.The regenerative braking experiment of AT under long downhill condition is carried out after having verified the feasibility of regenerative braking energy recovery of AT.The results show that the braking energy recovery of AT is ideal,and the energy of the battery can be improved by the the braking energy recovery,therefore,the driving range of the AT can be increased.