Energy Efficiency&Consumption Analysis And System Optimization Of Lithium Ion Battery Bus System And Supercapacitor Bus System

Bus is playing an important role in rural transportation network,but it is also one of the main sources of rural pollution.Pure electric bus system is suitable to the global requirement for energy saving and environmental protection,which is also a new bus system with great potential.Under the background that pure electric bus is replacing traditional fossil fuel bus,how to choose electric bus types and how to effectively reduce energy consumption by using today’s technology,are becoming the most challenging problems on electric bus application.Lithium-ion battery bus system and supercapacitor bus system are two types of pure electric bus systems in application.Due to the differences of their energy storage systems,the two systems have different charging and operation modes.This paper analyzes the energy efficiency of each component which participates in energy transmission,studies the real-time energy consumption during operation,and proposes an optimized bus charging distribution planning method.The main content is divided into the following three parts:Firstly,the energy storage system of pure electric bus was studied,which is composed of lithium-ion battery or supercapacitor.Lithium titanate battery and double-layer supercapacitor were selected as the research objects.The charging and discharging experiments were designed and completed.The energy efficiency and coulombic efficiency under different discharge conditions were studied.Then a real-time energy efficiency estimation model of energy storage components was built based on artificial neural network to estimate the energy efficiency and coulombic efficiency of the two energy storage components.According to test,the modeling error is less than 1%.Secondly,based on previous research on the efficiency of energy storage unit and electric powertrain system,a real-time energy consumption estimation model of pure electric bus was established.The energy consumption model estimates the real-time energy consumption of the vehicle during operation with known speed,acceleration,state of charge and road slope.In addition,by using the energy consumption estimation model,compared the energy efficiency and total consumption of two types of electric buses.Finally,for the supercapacitor bus’s charging station distribution problem,a dynamic programming method is proposed,which also analyzed actual traffic flow data and combined the vehicle energy consumption estimation model with the optimization progress.The method can help to reduce nearly 5%energy consumption.