蓄电池组定期放电制度的探讨

固定型铅蓄电池组采用浮充电方式运行并实行定期放电制度由来已久。经过多年的实践,笔者认为定期放电不仅没有重要意义,甚至是画蛇添足。既浪费人力和电力,又促使极板老化缩短蓄电池使用寿命,以致降低蓄电池组对直流负荷供电的安全可靠性。一、蓄电池的运行方式和充、放电次数对安全运行和寿命的影响从理论和实践中都证明了蓄电池的使用寿命与它的运行方式和充、放电次数有着密切的关系。因此,欲延长蓄电池的使用寿命,要将充电——放电方式运行的蓄电池组改为浮充电     

离网型风光互补路灯照明系统蓄电池充电控制研究

建立了光伏阵列、风力发电机和蓄电池模型,基于蓄电池最佳充电电流曲线,提出先恒流后恒压的两阶段充电方式,并利用双闭环PID控制实现了蓄电池的恒压限流充电.通过对该双团环控制系统仿真研究,结果表明该模型合理有效.     

独立光伏发电系统充放电控制策略

为了提高蓄电池的充电效率和延长蓄电池的使用寿命,提出了一种新的光伏发电系统充放电控制策略.该控制策略用双蓄电池代替以前的单一蓄电池,在充电过程中,蓄电池按照光伏系统提供的电流进行充电,根据蓄电池的充电电压特性和内部的温度特性来判别充电终止电压.同时,采用电压、温度微分模糊控制算法,既能防止光照强度、温度等外部环境发生变化而导致对蓄电池充电的提前切除,又可保护蓄电池的过充.仿真结果证明,该控制策略能显著提高蓄电池的充电效率和延长蓄电池的使用寿命.     

采用电量控制阀控式蓄电池充电时间的研究

根据阀控式蓄电池的特性,研究在铁路现场充电作业中的充电时间控制问题,提出通过蓄电池输入电量检测的方法控制蓄电池充电的方案。介绍了系统设计方案,以及实际应用中的优缺点比较。进一步论证了采用电量作为蓄电池充电控制参数的优点。     

光伏系统中蓄电池充电过程的建模与仿真

蓄电池的充放电管理一直是其控制器的关键.为提高光伏系统中蓄电池的充电效率,延长蓄电池使用寿命,采用脉宽调制的三段式充电策略(快速充电、脉冲式恒压充电及浮充电),利用MATLAB/Simulink软件平台对整个系统进行建模并仿真,为光伏系统中蓄电池的充放电管理提供了参考与依据.仿真结果验证了系统仿真模型的可用性和通用价值以及蓄电池控制策略的可行性和合理性,并表明在此蓄电池管理策略下可提高蓄电池充电效率,延长其使用寿命.     

光伏系统高效互补充电的控制

采用"1+1"并联蓄电池组取代同容量单组蓄电池,并利用智能化充电互补控制系统对蓄电池充电,可以提高太阳电池方阵的利用率,解决由于太阳电池方阵脉冲间歇充电不足所引起的单组蓄电池极板极化问题,使蓄电池不再处于虚满状态,从而延长蓄电池寿命,减小能量损耗,降低光伏系统的成本。     

基才AVR单片机的光伏系统充电器的设计

文章分析了光伏阵列输出能量特点和蓄电池充电特点,提出了一种新的控制方法,并设计出基于AVR单片机的光伏系统充电控制器。试验证明该控制器在充分利用光伏阵列能量同时能提高蓄电池充电效率。较理想地实现了对光伏系统中储能蓄电池的充电控制。     

简单实用的全自动蓄电池充电控制器

太阳能光伏电源是将阳光转变成电能的发电系统,而蓄电池充电控制器是光伏系统中的关键设备之一。一般的充电控制器当蓄电池电压上升到过充点电压时,控制器自动断开充电回路。然而由于蓄电池内阻的作用,断开充电回路后蓄电池电压会立即下降。而当充电回路接通及控制器断开用电负载后,同样由于蓄电池内阻的作用,蓄电池电压会立即上升。如此反复控制器极易产生振荡,不但使控制器工作不正常,而且还容易损坏蓄电池。本文介绍的充电控制器线路简单、功能全,不但具有防过充过放及自动切断负载的功能,而且具有防止输出振荡和浮充功能,线路如图1所示…     

基于AVR单片机的光伏系统充电器的设计

文章分析了光伏阵列输出能量特点和蓄电池充电特点,提出了一种新的控制方法,并设计出基于AVR单片机的光伏系统充电控制器.试验证明该控制器在充分利用光伏阵列能量同时能提高蓄电池充电效率,较理想地实现了对光伏系统中储能蓄电池的充电控制.     

基于FPGA的应急电源充电装置设计

传统的应急电源充电机常采用DSP作为处理器,实时控制效果不理想,鉴此研制了以FPGA EP3C25E144C8N为控制芯片的三相PWM整流装置作为应急电源蓄电池组充电机。采用基于空间矢量算法(SVPWM)的双闭环前馈解耦控制策略和分级定流的蓄电池充电方式,并编制了VHDL,语言控制程序,实现了蓄电池安全可靠充电。系统仿真和样机实验结果验证了文中设计的三相PWM整流充电装置的正确性。     

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。     

Development of an optimal charging algorithm of a Ni-MH battery for stationary fuel cell/battery hybrid system application

When installed in stationary fuel cell/battery hybrid systems, sealed nickel-metal hydride (Ni-MH) battery packs have low rates of charging behavior at high temperatures. They can also be charged with surplus power from fuel cell system when they are part of a small-capacity fuel cell/battery hybrid system. Test results indicate that when subjected to high temperatures and low rates of charging current, a Ni-MH battery experiences a sharp reduction in discharge capacity but does not experience an increase in voltage. To solve these problems, we have applied a new charging algorithm based on this pulse charging method to a Ni-MH battery. The pulse charging method reduces the charging time by 2 hrs and has a charging efficiency of over 97%. The charging current factor (β) in this pulse charging method should influenced the controlling the charging rate to the battery with applied voltages. The results show a 27% increase in efficiency with the new charging method compared to the system efficiency of the conventional constant-voltage charging method. Such a pulse charging method is expected to increase the lifespan of a Ni-MH battery by inhibiting gas generation.     

A study on quick charging method for small VRLA batteries

It is necessary for VRLA batteries to be charged quickly in many applications. Four-step tapering current charging is utilized to study quick charging for small VRLA batteries in this paper. With the measurement of charging parameters, such as charging time, water loss, temperature rise, as well as charging efficiency, it is found that the best initial current for quick charging is within 1–1.5 CA. Then a few group of batteries are taken to conduct cyclic life testing, also a recovery charging every 30 cycles is adopted since the charging regime is partial state of charging. The result shows that a better lasting life under quick charging regime is achieved compared to that under conventional charging. Thereafter failed batteries have been torndown and analyzed, it is found that favorable connectivity among positive particles and better activity of active material is formed under quick charging regime in comparison to that under conventional charging method through SEM, XRD and other electrochemical analysis. It is also found the failure mode under quick charging regime lies in the accumulation of passivation layer at the grid interface, which results in a higher impedance and eventually capacity deterioration.     

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.     

Numerical study of flow and heat transfer characteristics in hot water stores

The flow and heat transfer characteristics in a cylindrical hot water store during the charging process under adiabatic thermal boundary conditions were studied numerically in the present paper. The charging efficiency was used to evaluate the thermal stratification. The emphasis was put on the effects of charging temperature differences, charging velocities, charging flow rates and length to diameter ratios on the charging efficiency. The results were summarized both in dimensional and dimensionless forms. They indicate that the charging efficiency depends mainly on the modified Richardson number Ri_H,f and Peclet number Pe_H,f, which present the combined effects of charging temperature difference and charging velocity on the charging efficiency. If Ri_H,f is larger than 0.25, the charging efficiency is above 97%. At a given Richardson number the increase of Peclet number leads to a higher charging efficiency. For H/D less than 4, the increase of the height to diameter ratio H/D can improve the charging efficiency as well. The effect of the Fourier number (or charging flow rate) on the charging efficiency, however, is relatively small. A correlation of the numerical results was obtained for the design of effective hot water stores.     

基于动态规划的电动汽车用户侧充电优化方法

实现电动汽车有序充电是将电动汽车纳入智能电网的重要内容之一。从电动汽车用户需求角度出发,提出了以用户为充电过程决策主体的有序充电方法。以充电费用最低为目标建立了用户侧优化模型,并应用动态规划建立了求解方法。按照给定算例,对电动汽车的充（放）电过程进行了决策。计算结果表明,在满足功率约束和用户充电目标的前提下,通过用户优化控制策略可有效减少电动汽车充电过程产生的费用。该文提供了电动汽车有序充电的用户层方案。     

Modeling of fast charging station equipped with energy storage

The popularization of EVs (electric vehicles) has brought an increasingly heavy burden to the development of charging facilities. To meet the demand of rapid energy supply during the driving period, it is necessary to establish a fast charging station in public area. However, EVs arrive at the charging station randomly and connect to the distribution network for fast charging, it causes the grid power to fluctuate greatly and the peak-valley loads to alternate frequently, which is harmful to the stability of distribution network. In order to reduce the power fluctuation of random charging, the energy storage is used for fast charging stations. The queuing model is determined to demonstrate the load characteristics of fast charging station, and the state space of fast charging station system is described by Markov chain. After that the power of grid and energy storage is quantified as the number of charging pile, and each type of power is configured rationally to establish the random charging model of energy storage fast charging station. Finally, the economic benefit is analyzed according to the queuing theory to verify the feasibility of the model.     

Optimal charging strategy design for lithium‐ion batteries considering minimization of temperature rise and energy loss

Battery charging techniques are critical to enhance battery operation performance. Charging temperature rise, energy loss, and charging time are three key indicators to evaluate charging performance. It is imperative to decrease temperature rise and energy loss without extending the charging time during the charging process. To this end, an equivalent circuit electrical model, a power loss model, and a thermal model are built in this study for lithium‐ion batteries. Then, an integrated objective function is formulated to minimize energy loss and temperature increment during battery charging. To further validate the generality and feasibility of the proposed charging strategy, experiments are conducted with respect to different current, operating temperatures, battery types, and aging status. Comparison results demonstrate that the devised charging strategy is capable of achieving the intended effect under any operating temperature and with different aging status.     

Multi-step constant-current charging method for electric vehicle,valve-regulated,lead/acid batteries during night time for load-levelling

For the popularization of electric vehicles (EVs), the conditions for charging EV batteries with available current patterns should allow complete charging in a short time, i.e., less than 5 to 8 h. Therefore, in this study, a new charging condition is investigated for the EV valve-regulated lead/acid battery system, which should allow complete charging of EV battery systems with multi-step constant currents in a much shorter time with longer cycle life and higher energy efficiency compared with two-step constant-current charging. Although a high magnitude of the first current in the two-step constant-current method prolongs cycle life by suppressing the softening of positive active material, too large a charging current magnitude degrades cells due to excess internal evolution of heat. A charging current magnitude of approximately 0.5 C is expected to prolong cycle life further. Three-step charging could also increase the magnitude of charging current in the first step without shortening cycle life. Four-or six-step constant-current methods could shorten the charging time to less than 5 h, as well as yield higher energy efficiency and enhanced cycle life of over 400 cycles compared with two-step charging with the first step current of 0.5 C. Investigation of the degradation mechanism of the batteries revealed that the conditions of multi-step constant-current charging suppressed softening of positive active material and sulfation of negative active material, but, unfortunately, advanced the corrosion of the grids in the positive plates. By adopting improved grids and cooling of the battery system, the multistep constant-current method may enhance the cycle life.     

Design of PC-based quantitative split charging device for hydrogen isotope elemental gases

A quantitative split charging device for hydrogen isotope elemental gases in the operation ranges of 10^?5 Pa ? 6 bar, 15–40 °C, and 10–500 sccm, controlled by a personal computer (PC) on the workbench of LabVIEW software, was carefully designed and constructed. In the device, volumetric charging mode and flow-controller charging mode can be adopted according to the molar quantity of split charging. The leakage rate and the quantitative split charging accuracy of the set-up were evaluated systemically. According to the experimental results of quantitative split charging from our device and mass comparator, this apparatus is well designed and assembled, and can guarantee 0.001 g quantitative split charging accuracy in the two charging modes.