不同模式下电动汽车充电负荷及充电设施需求数量计算

电动汽车充电设施技术路线的选择可从多种角度出发。基于现有充电设施特性和用户需求分析,对常规充电、快速充电、电池更换3种模式下的充电负荷进行了建模。应用蒙特卡罗仿真方法计算了3种模式下一定规模电动汽车在一日内的充电负荷曲线。根据一日中最大在线充电汽车数量得出快速充电设施的数量需求,根据换电站内充满电和正在充电电池数量的计算,得出换电站电池配置数量需求。计算结果表明,由于充电相对集中,一定规模电动汽车采用慢速充电时其电力需求最大。相比于慢速充电,快速充电和电池更换模式一定程度上提高了设施的利用率,但为了保证换电服务,换电站需配置足够数量的电池。     

V2G or VEG?An investigation into the business model for future electric vehicles based on technological developments

基于目前电动汽车产业发展的困境认识,提出未来电动汽车技术发展与商业实现的VEG模式(Vehicle-Energy station-Grid).在VEG模式中,电动汽车充电方式由用户自己选择,可以在能量站快充,也可以在停车场或家庭车库进行慢充.能量站安装有低成本,长寿命的MW级储能电池,能够从电网充电储存电量后给电动汽车快速充电;同时,能量站能够与电网互动,用于电力调峰或调频.作者认为,开发低成本长寿命的新型储能电池和可以安全快速充电的新型动力电池是实现VEG模式的两大技术关键.只有这两大技术关键突破后,纯电动汽车产业发展的春天才能够真正到来.     

电动汽车充换电混合运行方式和电网储能协同发展的探讨

家用电动汽车的发展面临着两个致命的问题:一是在电池的生命周期内无法收回电池成本;二是电动汽车充电时间长,限制了其使用的便捷性。目前电动汽车的研究方向及应用方案基本都是围绕这两个问题展开的,比如:增加电池的循环次数,提高电池的单位容量以增加续驶里程,利用换电站更换蓄电池等等。但是家用电动汽车用户的行为特性决定了目前的应用方案都不是最优解决方案。为此,本文提出了一种单车充换电混合的运行方式,并探讨了新的电动汽车和电网储能协同发展的运行模式,以期为家用电动汽车的推广提供一种新的思路。     

我国电动汽车市场推广分析及建议

电动汽车是实现“以电代油”及碳减排的有效手段.同样行驶100km路程,在不考虑电池购置成本的前提下,电动汽车耗费成本18.9元,燃油汽车耗费成本80元,是电动汽车的4.23倍;按照当前电源结构计算,假设电动汽车电源均来自燃煤发电及清洁能源发电,且清洁能源发电不排放二氧化碳,则电动汽车可比燃油汽车降低二氧化碳排放量约42％;同时燃油替代效果明显,理论上6座试点换电站可替代燃油29510～31580t,71座试点充电站可替代燃油77033t,7031个交流充电桩可替代燃油76989t.虽然我国推广电动汽车具有一定的优势,但也面临着许多问题,如电池购置成本高、充电时间长,换电容易带来新旧电池管理及电池产权问题,经济效益不理想,尤其是电动汽车无序大量充电将影响电力系统的安全可靠运行,因此现阶段我国不适合大规模推广电动汽车.技术进步是发展电动汽车的关键因素,目前应加大电池技术研发力度,降低工程造价,提高服务能力,规范电池标准和插头标准,加强充换电设施建设,只有提高电池技术水平及清洁能源发电比重,才能真正推动我国电动汽车市场的健康稳定发展.     

充换电站电动公交车自动有序充电系统设计

摘要： 对于服务于电动公交车的充换电站,单位时间内可供更换的动力电池越多,整站服务能力就越强。运用动态规划的充电控制策略和动力电池的状态评价体系,借助共享配电数据,关注站内负荷变化,调节充电功率消耗,达到站内自动有序充电的控制目标,实现可供更换动力电池数量最大化。同时,根据工位需求情况、可换电池组数等信息,通过充电机与其电气连接的充电架,设计对放置于电池架的动力电池自动充电功能,制定合适的自动有序充电计划。最后,跟踪电池全寿命周期信息,结合一段时间换电效率判断充电监控设计效果,提高整站自动化水平和运行效率。     

电动汽车“换电”还是“充电”？

7月22日,南方电网首次对外公布其电动汽车发展方针——“换电为主、充换结合、统一服务、统一配送”。而在此前,国家电网公司总经理刘振亚也高调宣称,国家电网将电动汽车的基本商业运营模式确定为：换电为主、插充为辅、集中充电、统一配送。两大电网公司一致宣称的“换电为主,充电为辅”的发展模式,     

基于群系统一致性电动车充电桩接入微电网的控制研究

针对电动汽车快速充电和动力电池换电功率大,造成变流器不均流问题,文章提出群系统一致性策略对群充电桩进行协同控制。考虑充电桩节点间的通信拓扑和信息交互权值以及有充电桩退出系统等客观情况,分析了系统收敛特性,然后将交互后的一致性信息与电压、电流双闭环控制策略相结合,实现了群充电桩的电压、电流状态快速一致。Matlab/Simulink仿真结果表明,所提控制方案能有效地实现多充电变流器的电流一致和电压稳定,对实现电动汽车快速充电和大规模动力电池充换电有一定的理论意义。     

电动汽车换电网络规划研究综述

换电模式是电动汽车的一种重要能源供给模式,但是目前还没有形成一套成熟的换电网络布局规划体系。通过总结梳理当前换电网络规划的研究现状,从换电网络规划研究对象和内容等方面进行详细介绍,归纳了与换电网络相关的电池数量、配送站、集中型充电站、换电站及电网规划等问题的研究进展,可为未来电动汽车换电网络基础设施规划理论框架的形成提供参考。     

我国电动汽车大规模接入电网影响分析与建议

为了分析我国未来电动汽车大规模接入电网充电对电网的影响,本文首先分析了电动汽车充电负荷的特性,并定量计算了不同能源补给方式下,全国电动汽车作为充电负荷的电量和电力需求。结果表明,至2020年,充电负荷占总负荷的比例很小。到2030年,充电负荷占全网负荷的比例较高。无序充电情景下,充电负荷有一个明显的晚高峰,将会较大的增加电网的峰荷需求及峰谷差。充电负荷具有较大的调控潜力,换电模式总负荷峰荷小于充电模式。本文从规划和运行的角度研究了充放电优化对于电网的效益。计算结果表明,从规划的角度,充放电优化具有较大的容量效益,从运行的角度,充放电优化能够有效提高电网运行的可靠性,但其总成本不能忽略。提出了积极应对电动汽车大规模接入电网充电,应在研究和相关政策等方面采取措施的建议。     

Research and characterization of pulse charging strategy for lithium-ion traction battery

动力电池充电策略对提高电动汽车性能和使用寿命起着至关重要的作用。针对一种三元材料体系18650圆柱形电池进行脉冲充电策略研究,将其与标准恒流恒压充电策略进行综合比对,全面客观地分析脉冲充电策略关键参数对动力电池电性能的影响,并系统地评估了脉冲充电策略对电池寿命的影响。在循环寿命研究方面,采用电化学交流阻抗欧谱（EIS）分析不同循环周数和SOC下的交流阻抗,采用X射线断层扫描（CT）无损分析技术对循环500周后电池结构进行表征分析,揭示了带负脉冲充电策略对电池循环性能和结构影响的关系。     

电动汽车的能耗效率分析及提高能耗经济性的研究

通过对比电动汽车和内燃机汽油车的热效率及能耗,得出电动汽车的热效率及能耗明显优于内燃机汽油车的结论,并推断出降低电动汽车的运行能耗、提高其经济性是推动电动汽车产业化的关键因素之一。从整车动力系统、电池以及充电设备等几个方面分析了提高电动汽车能耗经济的途径,指出了今后需要重点研究的关键性问题。     

Investigation of battery end-of-life conditions for plug-in hybrid electric vehicles

Plug-in hybrid electric vehicles (PHEVs) capable of drawing tractive energy from the electric grid represent an energy efficient alternative to conventional vehicles. After several thousand charge depleting cycles, PHEV traction batteries can be subject to energy and power degradation which has the potential to affect vehicle performance and efficiency. This study seeks to understand the effect of battery degradation and the need for battery replacement in PHEVs through the experimental measurement of lithium ion battery lifetime under PHEV-type driving and charging conditions. The dynamic characteristics of the battery performance over its lifetime are then input into a vehicle performance and fuel consumption simulation to understand these effects as a function of battery degradation state, and as a function of vehicle control strategy. The results of this study show that active management of PHEV battery degradation by the vehicle control system can improve PHEV performance and fuel consumption relative to a more passive baseline. Simulation of the performance of the PHEV throughout its battery lifetime shows that battery replacement will be neither economically incentivized nor necessary to maintain performance in PHEVs. These results have important implications for techno-economic evaluations of PHEVs which have treated battery replacement and its costs with inconsistency.     

Analysis of Adverse Effects on Performance due to Battery Deterioration Installed in BEV and HEV

This paper reports the results of investigating the permissible amount of battery deterioration. An investigation was carried out using the following two types of vehicles： a BEV （battery electric vehicle） and a HEV （hybrid electric vehicle）. First, a detailed evaluation was carried out to identify how the vehicle performance was adversely affected as the lithium-ion batteries installed in the vehicles deteriorated. Next, an attempt was made to determine the permissible amount of deterioration for the vehicle-mounted lithium-ion batteries. In the case of the BEV, the driving distance declined by 20% when the capacity maintenance rate was approximately 80%. Therefore, this was specified as the permissible amount of battery deterioration for the BEV. In the case of the HEV, the fuel consumption increased by 20% when the maximum battery output maintenance rate was approximately 40%. Therefore, this was specified as the permissible amount of battery deterioration for the HEV.     

一种电动汽车光伏充电站的分时段有序充电策略

  目的  针对电动汽车光伏充电站的有序充电问题,提出一种分时段有序充电策略。  方法  研究了光伏充电站的结构体系及工作原理,构造了电动汽车充电时间、储能电池荷电状态（SOC）范围等约束条件。负荷高峰时段,在满足车辆充电需求的同时,减少向电网的购电量,降低购电费用,并辅助电网“消峰”。负荷低谷时段,在满足车辆充电需求的同时,增加向电网的购电量,辅助电网“填谷”。  结果  通过仿真事例验证了所建模型的有效性,并与即时充电方案进行比较,说明了所建模型在减小充电站的购电费用,降低电网峰谷差方面的优势。  结论  所提电动汽车光伏充电站的充电策略是正确并有效的,可为实际应用提供参考。     

Cost-effectiveness of plug-in hybrid electric vehicle battery capacity and charging infrastructure investment for reducing US gasoline consumption

Federal electric vehicle (EV) policies in the United States currently include vehicle purchase subsidies linked to EV battery capacity and subsidies for installing charging stations. We assess the cost-effectiveness of increased battery capacity vs. nondomestic charging infrastructure installation for plug-in hybrid electric vehicles as alternate methods to reduce gasoline consumption for cars, trucks, and SUVs in the US. We find across a wide range of scenarios that the least-cost solution is for more drivers to switch to low-capacity plug-in hybrid electric vehicles (short electric range with gasoline backup for long trips) or gasoline-powered hybrid electric vehicles. If more gasoline savings are needed per vehicle, nondomestic charging infrastructure installation is substantially more expensive than increased battery capacity per gallon saved, and both approaches have higher costs than US oil premium estimates. Cost effectiveness of all subsidies are lower under a binding fuel economy standard. Comparison of results to the structure of current federal subsidies shows that policy is not aligned with fuel savings potential, and we discuss issues and alternatives.     

A novel multiobjective charging optimization method of power lithium‐ion batteries based on charging time and temperature rise

Power lithium‐ion batteries have been widely utilized in energy storage system and electric vehicles, because these batteries are characterized by high energy density and power density, long cycle life, and low self‐discharge rate. However, battery charging always takes a long time, and the high current rate inevitably causes great temperature rises, which is the bottleneck for practical applications. This paper presents a multiobjective charging optimization strategy for power lithium‐ion battery multistage charging. The Pareto front is obtained using multiobjective particle swarm optimization (MOPSO) method, and the optimal solution is selected using technique for order of preference by similarity to ideal solution (TOPSIS) method. This strategy aims to achieve fast charging with a relatively low temperature rise. The MOPSO algorithm searches the potential feasible solutions that satisfy two objectives, and the TOPSIS method determines the optimal solution. The one‐order resistor‐capacitor (RC) equivalent circuit model is utilized to describe the model parameter variation with different current rates and state of charges (SOCs) as well as temperature rises during charging. And battery temperature variations are estimated using thermal model. Then a PSO‐based multiobjective optimization method for power lithium‐ion battery multistage charging is proposed to balance charging speed and temperature rise, and the best charging stage currents are obtained using the TOPSIS method. Finally, the optimal results are experimentally verified with a power lithium‐ion battery, and fast charging is achieved within 1534 s with a 4.1°C temperature rise.     

Review of research on heat generation characteristics during charging and discharging of lithium ion batteries

电动车辆的性能和成本很大程度上取决于动力电池组的性能和使用寿命,而电池组的性能和使用寿命又受到电池单体产热的影响。研究锂离子电池充放电过程中的产热特性及影响因素,对锂电池的开发及使用具有指导意义。本文从环境温度、充放电倍率、电池材料、荷电状态和老化程度五个方面入手,综述了各因素对锂离子电池产热的影响。     

Estimation of power battery SOC based on firefly BP neural network

针对BP神经网络算法对电动汽车电池荷电状态（state of charge,SOC）估算的缺陷,提出一种基于萤火虫（firefly algorithm,FA）神经网络的SOC估算方法。以磷酸铁锂电池为测试对象,在ARBIN公司生产的EVTS电动车动力电池测试系统装置上进行测试,收集锂电池的各项性能参数。采用端电压和放电电流作为输入参数,SOC作为输出参数,建立FA-BP神经网络模型,用于估算锂离子电池充放电过程中的任一状态下的SOC。仿真实验结果表明,与现有的BP神经网络估算方法相比,基于FA-BP神经网络的锂电池SOC估算方法准确度高,具备很好的实用性。     

Impact of charging efficiency variations on the effectiveness of variable-rate-based charging strategies for electric vehicles

The huge energy demand coming from the increasing diffusion of plug-in electric vehicles (PEVs) poses a significant challenge to electricity utilities and vehicle manufacturers in developing smart charging systems interacting in real time with distribution grids.These systems will have to implement smart charging strategies for PEV batteries on the basis of negotiation phases between the user and the electric utility regarding information about battery chemistries, tariffs, required energy and time available for completing the charging. Strategies which adapt the charging current to grid load conditions are very attractive. Indeed, they allow full exploitation of the grid capacity, with a consequent greater final state of charge and higher utility financial profits with respect to approaches based on a fixed charging rate.The paper demonstrates that the charging current should be chosen also taking into account the effect that different charging rates may have on the charging efficiency. To this aim, the performances of two smart variable-rate-based charging strategies, taken as examples, are compared by considering possible realistic relationships between the charging efficiency and the charging rate. The analysis gives useful guidelines for the development of smart charging strategies for PEVs as well as for next-generation battery charging and smart grid management systems.     

Economic evaluation of fast charging electric vehicle station with second-use batteries energy storage system

由于电动汽车快速充电站大功率快速充电的特性会对电网的稳定造成冲击,因此考虑在电动车快速充电站中配置电池储能系统（BESS）,对充电站负荷进行削峰填谷,从而减少充电站变压器配置容量、缓解大功率快速充电对电网的不利影响。考虑到目前我国大量退役动力电池亟待回收利用的现状,结合梯次利用电池储能系统,建立了基于电动汽车快速充电站整体成本与收益的经济性评估模型,以快速充电站年净收益最大为目标函数,采用改进的遗传算法对模型优化求解。结合算例对快速充电站不配置储能、配置常规电池储能和配置梯次电池储能等不同情况进行了经济性评估,并综合考虑经济性与储能削减负荷的效果,确定了梯次电池储能系统最优容量配置方案。