Traceability Technology of DC Electric Energy Metering for On-Site Inspection of Chargers

The on-site inspection of high-power DC chargers results in new DC high-current measurement and DC energy traceability system requirements.This paper studies the traceability technology of electric energy value for automotive high-power DC chargers,including:(1)the traceability method of the built-in DC energy meter and shunt of the charger;(2)precision DC high current and small precision DC voltage output and measurement technology.This paper designs a 0.1 mA∼600 A DC high current measurement system and proposes a 0.005 level DC powermeasurement traceability system.The uncertainty evaluation experiment of theDC powermeasurement calibration system and the high-power DC charger’s on-site calibration experiment results verify the method’s effectiveness and feasibility in this paper.The experimental results show that the combined standard uncertainty of the DC power metering verification system can be 0.0451%.

Impact Analysis of Off-board Charger to Power Quality

In this paper, we tested the entire charging process of a single off-board charger in one charging station in Beijing. Among the testing data, we chose the typical power quality parameters and compared them with national standard. Then we drew conclusions as follows: 1) Electric vehicle battery is the capacitive load. It can export reactive power when charging. 2) In the charging process of the off-board charger, indicators of voltage deviation, frequency deviation, power factor, and voltage distortion rate are qualified. 3) Off-board charger produces odd harmonics in the charging process, and with increasing harmonic order, harmonic content reduces. There is a certain amount of high-order harmonic in off-board charger, mainly distributing around 6650 kHz. 4) Generated harmonics of the actual device, the harmonic is mainly reflected in the current, voltage, only a small distortion.

Comparison among Chargers of Electric Vehicle Based on Different Control Strategies

The charger of electric vehicle is a power electronic device which consists of rectifying devices and DC-DC converters. This nonlinear diode rectifier circuit has low power factor and high harmonic content. In order to improve power factor and reduce the harmonic distortion rate of the AC side current, single-phase non-controlled rectifier charger needs to install the active power factor correction device. A piece of power system analysis software which is called PSCAD is used in modeling of an EV charger which contains Boost-APFC. By means of simulation and analysis, differences of APFC characteristics between the hysteresis current control mode and average current control mode which has an influence on the power grid are compared. The consequence of simulation shows that the two control strategies achieve power factor correction and harmonic reduction requirements;Boost type power conversion circuit employs the average current control mode is better, which has following features: relatively faster settling time of the output voltage, relatively smaller overshoot, lower current harmonic distortion rate on AC side, lower switching frequency and better control effect.

Analysis of the Impact of Different PEV Battery Chargers during Faults

With a high penetration of Plug-In Electric Vehicles (PEVs) in the electric grid, utilities will have to face the challenges related to them. Considerable research is being done to study and mitigate the impact of PEVs on the electric grid and devise methodologies to utilize them for energy storage and distributed generation. In this paper, the impact of PEVs in a smart car park, placed in an unbalanced distribution system, during a Single Line to Ground fault with auto-recloser operation is studied. Level-2, bidirectional battery chargers with Current Controlled and Voltage Controlled Voltage Source Converters are modeled for the battery charging systems of the PEVs. A smart car park, with 16 vehicles connected to each of the three phases is simulated at one of the buses in the IEEE 13 Bus Test Feeder. The impacts observed during the fault are analyzed and a method to mitigate them is suggested.

基于GaN器件与磁集成技术的车载充电机实验平台研究

随着新能源汽车的普及,对车载充电机的要求越来越高。为了有效提升整机效率和功率密度,将GaN器件与磁集成技术应用于车载充电机,进行了实验平台研究。基于GaN器件设计了两级式车载充电机拓扑结构与外围电路,通过制作磁集成平面变压器,优化了CLLC变换器,完成了整机控制程序设计及2kW车载充电机实验样机搭建,并对样机进行了实验测试与波形分析。实验结果表明,实验样机具有良好的稳态特性与动态特性,整机功率因数在0.98以上,满载峰值效率达到95.22%。该平台能够帮助学生加深对电力电子技术的认识,掌握新型电力电子器件的特性及应用,锻炼实践操作能力,提高相关课程的教学质量。

基于DSP的锂电池充电供电控制系统设计

为满足电力机车在无电区的供电需求,同时兼顾锂电池(磷酸铁锂)的自动充电、供电要求和环境温度要求,本文在锂电池的充电和供电的需求基础上,设计了基于DSP的锂电池控制系统,对控制系统的总体设计、硬件电路、控制算法和程序等进行介绍,实现了锂电池充电以及供电的自动化运行策略。实验证明:本文设计的锂电池控制系统可有效满足锂电池充电和供电的要求,具有较好的实用性和可靠性。

动车组充电机直流支撑电容寿命评估方法研究

充电机是动车组直流供电系统的核心环节,而直流支撑电容是充电机中的关键元件,如何准确评估直流支撑电容的寿命状态对充电机的故障预测及修程修制的合理安排具有十分重要的意义。针对此问题,对动车组充电机直流支撑电容失效机理进行分析,研究不同失效模式对电容退化程度的影响及对应的失效判据;在此基础上,提出一种基于阿伦尼斯模型的电容双应力加速寿命模型;为验证所提模型的正确性,开展基于不同纹波电流和温度的加速寿命实验,通过加速寿命实验确定电容实际失效时间,其与电容双应力寿命模型计算所得的电容理论失效时间相比,误差小于8.7%,验证了所提电容双应力加速寿命模型的正确性。在此基础上,进一步提出动车组充电机直流支撑电容寿命评估方法,实现动车组充电机直流支撑电容在实际运营工况下寿命的准确评估。

电动公交车队规模与充电桩配置协同优化

为了保障电动公交系统的车辆能源供给和线路顺畅运营,本文在多线路与多充电站场景下考虑线路行程时间的随机性,建立面向线路层面的电动公交系统车辆与充电桩配置双层优化模型。模型以车辆和充电桩投资成本与乘客候车成本之和的最小化为目标,对各线路车队规模、各充电站充电桩数量及线路与充电站间的充电匹配关系进行优化决策。在下层模型中,为反映随机行程时间下车辆充电过程对线路运营的影响,引入顾客源有限下的多服务台排队模型来刻画固定线路与充电站匹配下的排队充电过程;在上层模型中,考虑充电站与场站容量约束,对电动公交系统的线路与充电站匹配关系进行优化。在求解方面,首先基于排队模型设计算法求解特定线路与充电站匹配下的车队规模及充电桩数量,进而利用CPLEX求解器对线路与充电站匹配关系进行优化。在实验环节,设计不同规模的算例验证本文所提双层模型与算法框架的有效性,计算结果表明,本文所提的双层模型和算法框架可在满足充电站和场站容量限制的前提下尽可能缩减车队成本、充电桩成本与乘客候车成本;相比较两种人工经验方法,本文算法可将总成本分别降低5.65%和4.54%。

Collaborative Charging Scheduling in Wireless Charging Sensor Networks

Wireless sensor networks (WSNs) have the trouble of limited battery power, and wireless charging provides apromising solution to this problem, which is not easily affected by the external environment. In this paper, we studythe recharging of sensors in wireless rechargeable sensor networks (WRSNs) by scheduling two mobile chargers(MCs) to collaboratively charge sensors. We first formulate a novel sensor charging scheduling problem with theobjective of maximizing the number of surviving sensors, and further propose a collaborative charging schedulingalgorithm(CCSA) for WRSNs. In the scheme, the sensors are divided into important sensors and ordinary sensors.TwoMCs can adaptively collaboratively charge the sensors based on the energy limit ofMCs and the energy demandof sensors. Finally, we conducted comparative simulations. The simulation results show that the proposed algorithmcan effectively reduce the death rate of the sensor. The proposed algorithm provides a solution to the uncertaintyof node charging tasks and the collaborative challenges posed by multiple MCs in practical scenarios.

High Power Density EV Integrated Fast Battery Chargers Based on the General Torque Cancelation Law for Three-Phase Motors

Integrated battery chargers are highly effective for saving costs and improving the power density of on-board chargers in electric vehicles (EVs), However, achieving torque elimination of the commonly used three-phase (3p) motors during the fast-charging process is challenging. In this paper, the general torque cancelation law applied in 3p permanent magnet synchronous motors (PMSMs) and induction motors (IMs) is derived to design high power density integrated fast battery chargers. Two novel integrated systems with fast-charging and vehicle-to-grid (V2G) capabilities are proposed based on this law. The main advantages of the proposed systems are: (1) Two filter inductors are constituted by the stator windings while charging, and only one external inductor and several contactors are supplemented to the motor-drive circuit. Therefore, the proposed integrated systems possess high power density;(2) The 3p open-winding (OW) motor is employed, with no need to modify the propulsion system or redesign the interior structure of the motor;(3) Employing an individual controller for each phase of the inner current loop control, the proposed systems realize unity power factors and low current harmonics in the fast-charging and V2G mode. Simulation and experimental results verify the feasibility of the proposed topologies and control strategies.

基于TRIZ理论的可自动灭火储物柜创新设计

近年来,充电器电池引发的火灾、办公室里高负荷工作引发的用电器短路以及高温爆炸等事故屡屡发生,本项目就此依据TRIZ理论(高水平高技术的理论创新分析)设计了一款可自动灭火的智能储物柜,内部设有温度传感器,快速检测火情,实现迅速、高效灭火,有效保护了重要资料,同时保证更多人的安全。储物柜还配备了GPS定位系统,实时定位,通知当地消防部门,让火灾事故的各个损失降到最低点。

面向充电机通信协议一致性测试的用例自动生成方法

现有的充电机和新能源汽车电源管理系统(BMS)之间的通信协议一致性测试方法主要由专家经验设计测试用例,这种方法缺乏理论支撑,导致测试覆盖性弱,测试结果缺乏说服力,较难形成行业标准.为了解决上述问题,提出一种基于有限状态机(FSM)的充电机与BMS通信协议一致性测试方法.首先,通过对GB/T 27930—2015协议的详细解读,分析充电机和BMS之间的通信过程,使用FSM形式化语言描述充电机和BMS之间的充电过程,保证协议的不同实体之间的通信一致性.其次,在FSM的基础上利用唯一输入输出(UIO)序列计算测试序列,进而得到最终的测试用例.在生成测试用例时,采用递归算法考虑前置用例,让每一个测试用例都有完整的输入输出.最后,生成的用例结果表明,基于FSM的一致性测试方法不仅使得充电机与BMS间的通信协议一致性测试过程有了理论支撑,而且相较于基于专家经验的手工设计测试用例方法具有更强的复用能力.

光伏-直流智能充电桩有序充电策略与应用效果

在双碳目标的指引下,建筑屋顶可作为分布式光伏的重要场景,同时汽车电动化是交通领域减碳的关键举措。然而,大量光伏出力和电动汽车充电需求在时间上的不匹配,给电网稳定性带来较大压力。提出一种光伏-直流智能充电桩的有序充电策略,在满足充电需求的基础上,减少外网供电,可有效提高光伏自消纳能力和负荷满足率。以北京市某办公建筑为例,通过实验测试和模拟计算,分析了不同天气条件下系统运行效果。结果表明,该充电策略可以完全利用建筑光伏满足电动汽车充电需求,无须向外网取电,即负荷满足率可达100%。与传统恒功率充电方式相比,光伏消纳率提高了42%,光伏最大并网功率下降了54%,为建筑光伏高效利用和交通领域电气化提供借鉴和参考。

关于电动汽车双向车载充电器的分析综述

双向车载充电器作为电动汽车-电网交互(V2G)技术实现的媒介之一,能够使得电动汽车的利用率最大化。本文将双向车载充电器分为两级式变换器与单级式变换器两类,整理了不同拓扑结构的双向车载充电器并加以优越性与局限性的分析。最后,通过各种性能的对比,给出了电动汽车双向车载充电器的前景展望。

集成型车载充电系统并网模式模型预测控制策略

相较于传统车载充电系统,集成型车载充电系统(integrated onboard charger system,IOCS)在成本、功率密度等方面具备显著优势。文中基于六相永磁电驱系统设计了一台IOCS,并研究了模型预测电流控制(model predictive current control,MPCC)算法在该系统并网模式下的应用。首先,分析所提IOCS的电路拓扑并建立数学模型,同时介绍传统MPCC的实施流程。然后,针对传统MPCC计算量大、稳态性能差等不足,提出一种基于占空比优化的MPCC(MPCC based on duty cycle optimization,DCO-MPCC)策略。一方面,减少备选电压矢量数量,降低电流预测环节带来的计算负担;另一方面,提出一种占空比优化技术,改善系统稳态性能。最后,通过实验验证了所提算法的有效性与优越性。实验结果表明,DCO-MPCC策略能够显著提升系统稳态性能并减少算法计算量。充电与车网互动(vehicle to grid,V2G)工况下,网侧电流总谐波畸变(total harmonic distortion,THD)分别降低6.18%与5.92%,算法运行时间减少17.54μs。

基于远程非车载充电机的现场校准方法研究

为了提高非车载充电机现场校准能力、改善现有技术中校验效率滞后等问题,设计了一种基于远程非车载充电机的现场校准方法。该方法通过CS5464非车载电机电能计量芯片实现非车载充电机电能计量与检测控制。在检测控制时,设计电压、电流计量电路检测等。在电能量计算时,通过MSP430FG4619核心微控制单元(MCU)芯片实现数据信息,如电压和电流的幅值、波形、频率和相位等的计算与控制。这些数据信息多角度、多方面地呈现非车载充电机工作参数信息。通过这些数据信息,可以全面反映现场校准情况、提高非车载充电机现场校准精度。通过模板校对算法,可以实现高精度非车载充电机现场校准核对,提高现场计量与核对能力。试验结果表明,该方法误差低。该方法为下一步技术研究提供新思路。

智慧光伏储能充电桩能源管理策略

本文描述了一种智慧光伏储能充电桩系统的架构,并提出了一种易于通过单片机实现的实时能源管理策略。不同于常见光储充方案采取交流母线的形式,该充电桩采用了直流母线电气架构。储能系统直接挂载在直流母线上,支撑母线电压,同时可通过功率变换器实现与电网、光伏与电动汽车之间的能量交换。通过分析该电气架构中的电能流经途径、寻找最高传输效率路径,并通过储能充分利用峰谷差价,制定规划了光储充多能互补平台下的能源管理策略。经分析计算,该策略能充分发挥光伏、储能的作用,实现储能日内低倍率充放,降低充电桩使用成本。以晴天非通勤车辆三次快速充电为例,通过该策略增加收入达28%。

基于新能源的太阳能无线充电器设计

阐述一款太阳能无线充电器的总体设计方案,硬件设计方案包括单片机模块选型、单片机选型、无线电力发射/接收芯片选型,软件设计方案包括AD转换程序设计、无线充电模块程序设计。

电动汽车充电桩远程核查装置的研制

本文提出了一种针对电动汽车充电桩的远程核查装置,并介绍各个单元的原理和特点;采用闭环霍尔电流传感器测量充电电流,提高电能计量的精度和在电动汽车充电时核查充电桩的电能计量准确度;根据充电桩的工作特点,设计装置自行测量电量方案,并依托现有无线通信技术建立数据平台。实验证明:该装置能降低检定人员工作强度、有效利用社会电动汽车资源,具有普遍适用性。

基于陶瓷绝缘导热结构的高压充电机模块设计

为了让电压等级较低的IGBT能够应用于耐压要求较高的充电机系统,需要从结构方面进行特殊设计,文章介绍了一款针对此设计的基于陶瓷绝缘导热结构的高压充电机模块。该绝缘导热结构在IGBT和散热器之间设置了陶瓷片,并在散热器表面的IGBT固定部位设计了受力可靠、绝缘性能良好的金属嵌件,使得IGBT对地绝缘耐压得到加强。通过对充电机模块的热仿真,以及金属嵌件结构的力学性能试验、IGBT绝缘耐压试验、模块温升试验和冲击振动试验等,证实了该充电机模块散热性能优异、绝缘性能良好,且结构安全可靠。