充电器基础知识

新能源电力基础知识九：PCS与逆变器的区别“电源转换系统（PCS）和逆变器(inverter)有什么区别呢？我们在这里解释一下。

1、什么是PCS？什么是逆变器？我们来先了解一下基本原理：•整流（rectifier）：交流AC变直流DC；•逆变（inverter）：直流DC变交流AC；•斩波（chopper）：直流DC变直流DC，分为基本斩波，复合斩波，带隔离的直流变直流；•变频（VFD）：交流AC变交流AC，包含交交变频，交交调压。

整流和逆变这个过程称为换流，换流设备称为换流站（converter）; 直流变直流和交流变交流这个过程我们称为变流，其实就是把一种形式的直流电（交流电）变成另一种形式的直流电（交流电）。

但是在英文表述里，变流和换流其实是一个单词，比如直流变直流中的降压电路叫buck converter。

为了区分这些能量的变化，有不同的名称。

但是本质上都是能量形式的转换，整流器（rectifier）、逆变器（inverter）、斩波器（chopper）及变频驱动器（VFD）皆为变流器的一种。

像平时所说的PCS更多的是多种能量变换的组合系统。

电源转换系统（PCS: Power Conversion System）是一种用于双向转换连接在电池系统与电网和/或负载之间的电能的设备。

该装置应具有充放电功能、有功无功功率控制功能和脱机切换功能。

逆变器(inverter)是将电压从直流电(DC) 转换为交流电(AC) 的电气设备。

2.交流和直流之间的区别？接下来让我们谈谈交流和直流之间的区别。

电流以两种方式流动：交流电(AC) 或直流电(DC)。

“电流”只不过是电子通过导体（如电线）的运动。

交流电和直流电的区别在于电子流动的方向。

在直流电（DC ）中，电子沿单一方向流动。

在交流电中，电子的流动是会转换方向的，有时“向前”，然后“向后”。

交流电是远距离输电（家用）的最佳方式。

现在我们知道了交流电和直流电之间的区别，让我们来谈谈我们用到的负载（例如空调、洗衣机、电磁炉、灯泡、点烟器等）。

《电源基础知识综合性概述》一、引言在当今科技高度发达的时代，电源作为各种电子设备和系统的动力源泉，其重要性不言而喻。

从我们日常生活中使用的智能手机、笔记本电脑，到工业生产中的大型机械设备、自动化控制系统，无一不需要稳定可靠的电源供应。

了解电源的基础知识，对于正确选择、使用和维护各种电子设备，以及推动电子技术的发展都具有重要意义。

本文将从电源的基本概念、核心理论、发展历程、重要实践以及未来趋势等方面进行全面的阐述与分析。

二、电源的基本概念1. 定义电源是将其他形式的能量转换为电能的装置。

它可以将化学能、机械能、太阳能等不同形式的能量转化为可供电子设备使用的电能，如直流电（DC）或交流电（AC）。

2. 分类（1）按能量来源分类：- 化学电源：如电池，通过化学反应将化学能转化为电能。

常见的有干电池、铅酸蓄电池、锂离子电池等。

- 物理电源：包括太阳能电池、温差发电器等，利用物理效应将其他形式的能量转化为电能。

- 机械电源：如发电机，通过机械运动将机械能转化为电能。

（2）按输出形式分类：- 直流电电源：输出恒定的直流电压和电流，如电池、直流稳压电源等。

- 交流电电源：输出交变的交流电压和电流，如市电、交流发电机等。

3. 主要参数（1）电压：表示电源输出电能的电位差，单位为伏特（V）。

不同的电子设备需要不同的电压等级，如手机充电器一般输出 5V电压，而笔记本电脑充电器可能输出 19V 电压。

（2）电流：指电源输出电能的流量，单位为安培（A）。

电子设备的工作电流取决于其功率需求和内部电路设计。

（3）功率：是电压和电流的乘积，单位为瓦特（W）。

它表示电源能够提供的电能大小。

（4）效率：电源的输出功率与输入功率之比，通常以百分比表示。

高效率的电源能够减少能量损失，降低发热，提高能源利用效率。

三、电源的核心理论1. 欧姆定律欧姆定律是电路分析的基础，它指出在同一电路中，通过某一导体的电流跟这段导体两端的电压成正比，跟这段导体的电阻成反比。

简易充电器的课程设计一、课程目标知识目标：1. 学生能理解并掌握简易充电器的基本电路原理，包括电压、电流、电阻的关系。

2. 学生能描述并解释简易充电器中各电子元件的作用及相互之间的关系。

3. 学生能够了解并阐述安全使用充电器的重要性及相关安全知识。

技能目标：1. 学生能够运用所学知识，设计并搭建一个简易的充电器电路。

2. 学生通过实践操作，提高动手能力和问题解决能力。

3. 学生能够运用科学方法，对简易充电器进行性能测试及数据分析。

情感态度价值观目标：1. 学生培养对电子技术的兴趣，激发创新意识和探索精神。

2. 学生在合作学习中，培养团队协作能力和沟通能力。

3. 学生认识到科技与生活的紧密联系，增强环保意识，培养节能习惯。

课程性质：本课程为电子技术实践课程，结合理论教学与动手实践，注重培养学生的实践能力和创新能力。

学生特点：初三学生具备一定的物理知识和动手能力，对电子技术有一定的好奇心，但需引导激发学习兴趣。

教学要求：教师需采用启发式教学，引导学生主动探索，注重理论与实践相结合，关注学生的个体差异，提高学生的综合素养。

通过具体的学习成果分解，使学生在课程结束后能够达到上述目标。

二、教学内容1. 理论知识：- 电路基础知识：电压、电流、电阻的概念及关系。

- 电子元件介绍：电阻、电容、二极管、三极管等。

- 充电器工作原理：开关电源、变压器、整流器、滤波器等。

- 安全知识：电器安全、电池安全、充电器使用注意事项。

2. 实践操作：- 搭建简易充电器电路：指导学生动手搭建，理解电路连接方式。

- 性能测试：测试充电器输出电压、电流，分析数据，评估性能。

- 故障排查：分析常见充电器故障，教授排查方法，提高问题解决能力。

3. 教学大纲：- 第一课时：电路基础知识回顾，电子元件介绍。

- 第二课时：充电器工作原理，安全知识讲解。

- 第三课时：实践操作，搭建简易充电器电路。

- 第四课时：性能测试，数据分析和故障排查。

教材关联：本教学内容与初三物理课本“电路”章节相关，涉及电路基础知识、电子元件、电器安全等内容，结合实践操作，使学生在掌握理论知识的同时，提高动手实践能力。

电气设计秒懂各种线路基础知识目录一、电路基础 (2)1.1 电流与电压 (3)1.2 电阻与功率 (4)1.3 电阻的连接方式 (4)二、直流电路 (6)2.1 串联与并联 (7)2.2 串并联电路的计算 (8)2.3 混合电路的分析 (9)三、交流电路 (10)3.1 正弦交流电的基本概念 (11)3.2 交流电路的分析方法 (12)3.3 常用交流电器的介绍 (13)四、变压器与电动机 (14)4.1 变压器的工作原理与结构 (15)4.2 变压器的使用与选择 (17)4.3 电动机的分类与工作原理 (18)4.4 电动机的控制与保护 (20)五、输配电线路 (21)5.1 输电线路的基本构成 (23)5.2 电力系统的稳定性与可靠性 (24)5.3 电力线路的敷设与防护 (25)六、电气安全与保护 (26)6.1 电气安全的基本知识 (28)6.2 电气设备的保护措施 (29)6.3 电气事故的预防与应急处理 (31)七、现代电气控制技术 (32)7.1 自动控制的基本原理 (33)7.2 继电保护的基本原理 (34)7.3 微型计算机在电气控制中的应用 (35)一、电路基础在电气设计中，电路是最基本的组成部分，它是由电源、导线、负载和开关等元件组成的。

了解电路基础知识对于电气设计师来说至关重要，因为它涉及到电路的工作原理、性能参数以及如何选择合适的元件来实现特定的功能。

本文档将为您介绍电路基础的一些关键概念，包括欧姆定律、基本电路元件、电路图和交流电路等。

欧姆定律是描述电阻、电压和电流之间关系的基本定律。

根据欧姆定律，电阻(R)与电流(I)成正比，与电压(V)成反比。

即：R表示电阻，V表示电压，I表示电流。

通过欧姆定律，我们可以计算出所需的电流值，从而确定合适的元件参数以满足设计要求。

在电气设计中，常见的基本电路元件有电阻器、电容器、电感器和二极管等。

这些元件具有不同的特性和参数，如阻值、容值、感值和导通特性等。

锂电池基础知识介绍在现代科技的飞速发展中，锂电池已经成为我们生活中不可或缺的一部分。

从智能手机、笔记本电脑到电动汽车，锂电池的身影无处不在。

那么，究竟什么是锂电池？它是如何工作的？又有哪些特点和类型呢？接下来，让我们一起走进锂电池的世界，了解一下它的基础知识。

一、锂电池的定义与工作原理锂电池，是一类由锂金属或锂合金为负极材料、使用非水电解质溶液的电池。

其工作原理主要基于锂离子在正负极之间的嵌入和脱嵌过程。

在充电时，锂离子从正极材料中脱出，经过电解质溶液，嵌入到负极材料中；而在放电时，锂离子则从负极脱出，经过电解质溶液，重新嵌入到正极材料中。

这个过程中，电子通过外电路从负极流向正极，从而产生电流，为我们的设备提供电能。

二、锂电池的主要特点1、高能量密度这意味着锂电池在相同体积或重量下，能够存储更多的电能，从而使设备具有更长的续航能力。

2、长循环寿命经过多次充放电循环后，锂电池仍能保持较好的性能，减少了更换电池的频率和成本。

3、低自放电率在不使用的情况下，锂电池自身消耗的电量相对较少，能够长时间保持电量。

4、无记忆效应不像某些其他类型的电池，锂电池在充电前不需要完全放电，使用起来更加方便。

5、快速充电能力能够在较短的时间内充满电，提高了使用效率。

三、锂电池的分类1、按照正极材料分类常见的有钴酸锂（LiCoO₂）、锰酸锂（LiMn₂O₄）、磷酸铁锂（LiFePO₄）、三元材料（如镍钴锰酸锂 Li(NiCoMn)O₂）等。

钴酸锂电池具有较高的能量密度，但安全性相对较差；锰酸锂电池成本较低，但循环寿命和能量密度相对较低；磷酸铁锂电池安全性高、循环寿命长，但能量密度相对较低；三元材料锂电池则在能量密度、循环寿命和成本之间取得了较好的平衡。

2、按照形状分类可分为圆柱形锂电池、方形锂电池和软包锂电池。

圆柱形锂电池如常见的 18650 电池，一致性较好；方形锂电池空间利用率高；软包锂电池则具有重量轻、形状灵活等优点。

BATTERY CHARGINGIntroductionThe circuitry to recharge the batteries in a portable product is an important part of any power supply design. The complexity (and cost) of the charging system is primarily dependent on the type of battery and the recharge time.This chapter will present charging methods, end-of-charge-detection techniques, and charger circuits for use with Nickel-Cadmium (Ni-Cd), Nickel Metal-Hydride (Ni-MH),and Lithium-Ion (Li-Ion) batteries.Because the Ni-Cd and Ni-MH cells are similar in their charging characteristics, they will be presented in a combined format, and the Li-Ion information will follow.NI-CD/NI-MH CHARGING INFORMATIONIn the realm of battery charging, charging methods are usually separated into two gen-eral categories: Fast charge is typically a system that can recharge a battery in about one or two hours, while slow charge usually refers to an overnight recharge (or longer).Slow ChargeSlow charge is usually defined as a charging current that can be applied to the battery indefinitely without damaging the cell (this method is sometimes referred to as a trickle charging ).The maximum rate of trickle charging which is safe for a given cell type is dependent on both the battery chemistry and cell construction. When the cell is fully charged, contin-ued charging causes gas to form within the cell. All of the gas formed must be able to recombine internally, or pressure will build up within the cell eventually leading to gas release through opening of the internal vent (which reduces the life of the cell).This means that the maximum safe trickle charge rate is dependent on battery chemis-try, but also on the construction of the internal electrodes. This has been improved in newer cells, allowing higher rates of trickle charging.The big advantage of slow charging is that (by definition) it is the charge rate that requires no end-of-charge detection circuitry, since it can not damage the battery regardless of how long it is used. This means the charger is simple (and very cheap).The big disadvantage of slow charge is that it takes a long time to recharge the battery,which is a negative marketing feature for a consumer product.Slow Charge RatesNI-CD: most Ni-Cd cells will easily tolerate a sustained charging current of c/10 (1/10 of the cell's A-hr rating) indefinitely with no damage to the cell. At this rate, a typical recharge time would be about 12 hours.Chester SimpsonNNational SemiconductorSome high-rate Ni-Cd cells (which are optimized for very fast charging) can tolerate continuous trickle charge currents as high as c/3. Applying c/3 would allow fully charg-ing the battery in about 4 hours.The ability to easily charge a Ni-Cd battery in less than 6 hours without any end-of-charge detection method is the primary reason they dominate cheap consumer products (such as toys, flashlights, soldering irons).A trickle charge circuit can be made using a cheap wall cube as the DC source, and a single power resistor to limit the current.NI-MH: Ni-MH cells are not as tolerant of sustained charging: the maximum safe trickle charge rate will be specified by the manufacturer, and will probably be somewhere between c/40 and c/10.If continuous charging is to be used with Ni-MH (without end-of-charge termination), care must be taken not to exceed the maximum specified trickle charge rate.Fast ChargeFast charge for Ni-Cd and Ni-MH is usually defined as a 1 hour recharge time, which corresponds to a charge rate of about 1.2c. The vast majority of applications where Ni-Cd and Ni-MH are used do not exceed this rate of charge.It is important to note that fast charging can only be done safely if the cell temperature is within 10-40°C, and 25°C is typically considered optimal for charging. Fast charging at lower temperatures (10-20°C) must be done very carefully, as the pressure within a cold cell will rise more quickly during charging, which can cause the cell to release gas through the cell's internal pressure vent (which shortens the life of the battery).The chemical reactions occurring within the Ni-Cd and Ni-MH battery during charge are quite different:The Ni-Cd charge reaction is endothermic (meaning it makes the cell get cooler), while the Ni-MH charge reaction is exothermic (it makes the cell heat up). The importance of this difference is that it is possible to safely force very high rates of charging current into a Ni-Cd cell, as long as it is not overcharged.The factor which limits the maximum safe charging current for Ni-Cd is the internal impedance of the cell, as this causes power to be dissipated by P = I2R. The internal impedance is usually quite low for Ni-Cd, hence high charge rates are possible.There are some high-rate Ni-Cd cells which are optimized for very fast charging, and can tolerate charge rates of up to 5c (allowing a fast-charge time of about 15 minutes). The products that presently use these ultra-fast charge schemes are cordless tools, where a 1 hour recharge time is too long to be practical.The exothermic nature of the Ni-MH charge reaction limits the maximum charging cur-rent that can safely be used, as the cell temperature rise must be limited.At present, there are no makers of Ni-MH batteries that recommend charging rates faster than 1.2c (and the chances of that changing are not very good).Fast Charge: Possible Cell DamageCaution: Both Ni-Cd and Ni-MH batteries present a user hazard if they are fast charged for an excessive length of time (subjected to abusive overcharge).When the battery reaches full charge, the energy being supplied to the battery is no longer being consumed in the charge reaction, and must be dissipated as heat within the cell. This results in a very sharp increase in both cell temperature and internal pres-sure if high current charging is continued.The cell contains a pressure-activated vent which should open if the pressure gets too great, allowing the release of gas (this is detrimental to the cell, as the gas that is lost can never be replaced). In the case of Ni-Cd, the gas released is oxygen. For Ni-MH cells, the gas released will be hydrogen, which will burn violently if ignited.A severely overcharged cell can explode if the vent fails to open (due to deterioration with age or corrosion from chemical leakage). For this reason, batteries should never be overcharged until venting occurs.In later sections, information is presented which will enable the designer to detect full charge and terminate the high-current charge cycle so that abusive overcharge will not occur.Fast Charge Current SourceBoth Ni-Cd and Ni-MH are charged from a constant current source charger, whose cur-rent specification depends on the A-hr rating of the cell.For example, a typical battery for a full-size camcorder would be a 12V/2.2A-hr Ni-Cd battery pack. A recharge time of 1 hour requires a charge current of about 1.2c, which is 2.6A for this battery.A cost-effective method to design a current source for this application would be to use an AC-DC wall cube to provide a DC voltage to a switching converter that is set up to operate as a constant-current source.Figure 1 shows a schematic diagram of a circuit which will fast-charge a 12V Ni-Cd or Ni-MH battery at 2.6A and trickle charge it when the converter is shut off.Note that the circuit must have a shutdown pin so that the end-of-charge detection cir-cuit(s) can terminate the fast charge cycle when the battery is full (the LM2576 has a low-power shutdown pin built in).A temperature sensing end-of-charge detection circuit suitable for use with this charger will be detailed later in this paper.The LM2576 is a buck (step-down) switching regulator, used as a constant-current source set to 2.6A. It provides good power conversion efficiency (about 80%) and oper-ates from a wide input voltage range.A constant-current feedback loop is established by holding the voltage at the Feedback pin of the LM2576 at 1.23V.The op-amp amplifies the voltage drop across the 50 m Ω sense resistor (with a gain of 9.2) which locks the loop at the value of charging current that causes the output of the op-amp to be 1.23V.The resistor R TR is included to provide a "trickle charge" current when the LM2576 is turned off. Current flows through this resistor any time the input voltage is present. The value of this resistor must be calculated based on the maximum allowable trickle charge current for the battery selected (equation shown in Figure 1).The total charging current during fast charge is the sum of the current coming from the LM2576 (about 2.6A) and the trickle charge current provided by resistor R TR .The following section details end-of-charge detection information and provides a circuit example in Figure 3 which can be connected directly to the circuit shown in Figure 1and provide end-of-charge shutdown.End-of-Charge Detection for Ni-Cd/Ni-MHBoth Ni-Cd and Ni-MH batteries can be fast charged safely only if they are not over-charged .By measuring battery voltage and/or temperature, it is possible to determine when the battery is fully charged.Most high-performance charging systems employ at least two detection schemes to ter-minate fast-charge: voltage or temperature is typically the primary method, with a timer as the back-up in case the primary method fails to correctly detect the full charge point.12V/2.2A-HR NI-CD/NI-MHV IN GND20-30VR TR*PROVIDES TRICKLE CHARGE CURRENT WHEN THE LM2576 IS OFF. SELECT VALUE USING:R TR =(V IN -15)I TRFIGURE 1. 2.6A NI-CD/NI-MH CHARGER253035B AT T E R Y T E M P (°C )TIMEB A T T E R Y V O L T A G EB A T T E R Y T E M P (°C )B A T T E R Y V O L T A G E40FIGURE 2. V/T PLOTS FOR 1C CHARGE RATEThe voltage/temperature plots in Figure 2 define the battery "signature" that shows when full charge has been reached (both Ni-Cd and Ni-MH are shown for comparison).For both plots, the data was taken on a single cell that was charged from a constant cur-rent source at a rate of 1c, and the ambient temperature was 25°C.As shown, the full charge point can be determined by sensing the cell temperature or cell voltage .Temperature sensing is preferable to voltage sensing because the cell temperature gives the most accurate information about what is happening within the cell. However, if the cell temperature is to be accurately measured, the temperature sensor must be built into the battery pack which increases the manufactured cost of the battery.Voltage sensing is easier, because the voltage leads are easily accessible and require no special assembly in the battery pack.Temperature Detection MethodsThe Ni-Cd cell shows no significant temperature increase until nearing full charge, as the internal charge reaction is endothermic (the Ni-Cd cell actually gets slightly cooler during the charging process).As full charge is reached, the amount of energy used in the endothermic charge reaction decreases and the amount dissipated in heat increases (making the cell get hot).The temperature in the Ni-MH cell increases all during the charge process, as its charge reaction is exothermic . However, as full charge is reached, the rate of temperature rise increases very sharply.It can be seen that the cells have one important characteristic in common: both show a cell temperature rise of about 10°C above ambient when the cell is fully charged (assuming a 1c charge rate).A circuit which can cut off the high current charge at this 10°C rise point can be used with either battery type: this circuit is called a ∆T detector.∆T DETECTORFigure 3 shows a schematic diagram of a circuit which measures both the ambient tem-perature and the battery temperature and produces a high signal when the cell tempera-ture is 10°C above ambient.The signal coming from the ambient sensor (10 mV/°C) is level shifted up 100 mV by a unity-gain buffer stage (the 100 mV shift corresponds to 10°C).The signal from the battery sensor is compared to the level-shifted ambient signal by the second amplifier, which is connected as a comparator.When the two signals are equal, the battery temperature is 10°C above ambient, and a high signal is provided on the S/D line which can be used to shut off the high current charger shown in Figure 1.TEMPERATURE SLOPE DETECTIONDuring fast charge, the temperature of both Ni-Cd and Ni-MH cells starts increasing very rapidly when full charge is reached (see Figure 2).A circuit which measures the rate-of-change (slope) of the cell temperature can be used for end-of-charge detection with both Ni-Cd and Ni-MH batteries. This type of circuit is referred to as a ∆T/∆t detector, because it measures the change in battery temperature with respect to time.Temperature slope detection is typically used in µP-based systems: temperature read-ings are taken at timed intervals, and stored in memory. The present temperature read-ing is compared to the previous value, and the difference (which is the temperature increase) during that time period is calculated.S/DVBAT+VBAT-LM35AMBIENT SENSOR FIGURE 3. ∆T DETECTOR CIRCUITOnce the temperature change over a timed interval is known, the rate-of-change (slope) of the cell temperature is calculated and compared to a target value. When the target is reached, the fast charge is terminated (because the battery is fully charged).Unlike the ∆T detector shown in the previous section, it is not necessary to measure the ambient temperature in a ∆T/∆t system, because only the cell temperature is required.Voltage Detection MethodsThe voltage of a Ni-Cd and Ni-MH cell during fast charge can be used to determine when it is fully charged (see Figure 2): not by the magnitude of the voltage, but by the amount (or rate) of voltage change.The two techniques that will be discussed in this paper are -∆V and Slope Detection.-∆V DetectionA definitive signal that a Ni-Cd cell is fully charged can be seen when the cell voltage begins to dip (see Figure 2). This drop in battery voltage is used to terminate fast charge in a -∆V Detector, which continuously monitors the battery voltage and shuts off the charger when the voltage drops by a pre-set amount.The voltage of the Ni-Cd cell used to generate the data in Figure 2 dropped 45 mV when the cell temperature was 10°C above ambient (a 10°C rise is typically used as the full charge cutoff for a Ni-Cd cell that is charged at 1c). Battery makers typically recom-mend a -∆V detection threshold of 10-20 mV/cell in charging systems that are dedicated to Ni-Cd only.The Ni-MH cell also exhibits a dip in voltage, but it is much smaller (typically a few mV). This means that detecting the drop in Ni-MH requires circuitry that is about one order of magnitude more accurate (and noise immune) than is needed for Ni-Cd.It follows that a detector which is accurate enough to detect -∆V in Ni-MH can always be used with Ni-Cd, but the reverse is not true.Some relief is provided by the fact that the voltage dips in a multi-cell (series-connected) pack tend to be additive if the cells are well matched, which increases the signal that the -∆V detector circuit will see.Voltage Slope DetectionA µP-based system that can measure, store and compare battery voltage readings taken at timed intervals can accurately detect end-of-charge by using a method called voltage slope detection.This method of charge termination can be used with either Ni-Cd and Ni-MH, as long as the system accuracy, resolution, and noise immunity are adequate for the job.A µP-based system can use digital signal processing to attain higher levels of perfor-mance than is possible using strictly analog circuits.For example, improved noise margin and accuracy can be obtained by using a time-averaging technique, where multiple readings are taken in a narrow time interval and then averaged to get the data value to be stored for comparison. This greatly reduces the probability of a noise "hit" giving a false reading, thereby improving the noise figure of the overall system.If voltage slope detection is to be used with Ni-MH or Ni-Cd batteries, any one of three methods is typically used (refer to Figure 2):Decreasing Positive Slope: This termination method looks for the part of the voltage curve where it is rising more slowly, but still has positive slope. This point on the curve is just prior to the voltage peak.0∆V: In this case, fast-charge is terminated at the point on the voltage curve with zero slope, which is the peak of the curve. The detector system would identify zero slope when two successive voltage readings were the same over a timed interval.-∆V: The part of the curve which has negative slope (just past the peak of the curve) is denoted by successive voltage readings that reduce in value.3A Battery Charger with Logic-level ControlsThe current source that charges a battery must often be integrated into a µP-based system that controls the charging current applied to the battery.Also, it is often desirable to have more than one charging current available to accommo-date different size batteries.An example of how a 3A charger can be implemented with four selectable charging rates is shown in Figure 4.General DescriptionThe circuit shown in Figure 4 is a 3A (maximum) battery charger that uses a 52kHz switching converter to step down the input DC voltage and regulate the charging current flowing into the battery. The switching regulator maintains good efficiency over a wide input voltage range, which allows the use of a cheap, poorly regulated "DC wall adaptor" for the input source.The key feature of this circuit is that it allows the µP controller inside the PC to select from one of four different charging currents by changing the logic levels at two bits. The various charge levels are necessary to accommodate both Ni-Cd and Ni-MH type batteries, as they require slightly different charge methods.Both Ni-Cd and Ni-MH batteries can be charged at the high-current "c" rate up until the end-of-charge limit is reached, but the two batteries must be trickle-charged at different rates. The recommended trickle-charge rate for a Ni-Cd is typically c/10, but for Ni-MH, most manufacturers recommend that the trickle charge rate not exceed c/40.+V IN V IN POWERSYSTEM RETURNLOGIC LEVELCONTROLSB1NOTES (UNLESS OTHERWISE SPECIFIED):1) ALL RESISTORS ARE IN OHMS, 5% TOLERANCE, 1/4W 2) ALL CAPACITORS ARE IN µF3) Q1 AND Q2 ARE MADE BY SUPERTEX4) FOR 3A CURRENT, U1 REQUIRES SMALL HEATSINK (RTH ≤15°C/W)BENCH TEST DATA:FIGURE 4. 3A CHARGER WITH LOGIC-LEVEL CONTROLSThe primary objectives of the design was to charge a 3A-hr Ni-Cd or Ni-MH battery with high efficiency, using logic-level signals to control the charging current.The four selectable charge rates are 3A, 0.75A, 0.3A, and 0.075A which correspond to charge rates of c, c/4, c/10, and c/40 for the 3A-hr battery used in this application.Circuit Operation (See Figure 4)The unregulated DC input voltage is stepped down using an LM2576 3A buck regulator, providing up to 3A of current to charge the battery.In order to regulate the amount of charging current flowing into the battery, a current control loop is implemented using op-amp U2. The voltage drop across the sense resistor R8 provides a voltage to U2 that is proportional to the charging current.The 0.05Ω value for R8 was specified by the customer in this application to minimize the power dissipated in this resistor. If a higher Ohmic value is used (more resistance), a larger sense voltage is developed and a less precise (cheaper) op-amp can be used at U2, since the input offset voltage would not be as critical (of course, increasing the value of R8 also increases its power dissipation).When the current-control loop is operating, the voltage at the feedback pin of U1 is held at 1.23V. The battery charging current that corresponds to this voltage is dependent on the overall gain of U2 and the attenuators made up of Q1, Q2 and the resistors R10, R11, R2 and R3.Turning Q1 on (by putting a "1" on logic input "A") provides an increase of 4:1 in load current. The load current is higher with Q1 on because R2 and R3 divide down the output of U2 by 4:1, requiring U2 to output a higher voltage to get the 1.23V on the feedback line of U1. Higher voltage at the output of U2 means that more charging current is flowing through R8 (also the battery).The operation of Q2 is similar to Q1: when Q2 is turned on by putting a logic "1" on input "B", the load current is increased by a factor of 10:1. This is because when Q2 is on, the sense voltage coming from R8 is divided down by R10 and R11, requiring ten times as much signal voltage across R8 to get the same voltage at the non-inverting input of U2.Although both attenuating dividers could have been placed on the input side of U2, putting the 4:1 divider at the output improves the accuracy and noise immunity of the amplifier U2 (because the voltage applied to the input of U2 is larger, this reduces the input-offset voltage error and switching noise degradation).R5, R6, and D2 are included to provide a voltage-control loop in the case where the battery is disconnected. These components prevent the voltage at the cathode side of D3 from rising above about 8V when there is no path for the charging current to return (and the current control loop would not be operational).Capacitor C2 is included to filter some of the 52kHz noise present on the control line coming from U2. Adding this component improved the accuracy of the measured charging current on the breadboard (compared to the predicted design values).Performance data measured on the breadboard is listed in Figure 4.LI-ION CHARGING INFORMATIONA Li-Ion battery is unique, as it is charged from a fixed voltage source that is current lim-ited (this is usually referred to as constant voltage charging ).Constant Voltage ChargingA constant voltage (C-V) charger sources current into the battery in an attempt to force the battery voltage up to a pre-set value (usually referred to as the set-point voltage or set voltage ).Once this voltage is reached, the charger will source only enough current to hold the voltage of the battery at this constant voltage (hence, the reason it is called constant voltage charging).At present, the major Li-Ion cell manufacturer recommends 4.200 +/- 50 mV as the ideal set point voltage, and 1c (a charging current rate equal to the A-hr rating of the cell) as the maximum charging current that can be used.The accuracy on the set point voltage is critical: if this voltage is too high, the number of charge cycles the battery can complete is reduced (shortened battery life). If the volt-age is too low, the cell will not be fully charged.A typical charge profile for a Li-Ion cell using 1c constant voltage charging is shown in Figure 5.01002401C% CHARGE DELIVEREDCELL VOLTAGECHARGE RATEFIGURE 5. TYPICAL C-V CHARGE PROFILEThe constant voltage charging cycle is divided into two separate segments:The current limit (sometimes called constant current ) phase of charging is where the maximum charging current is flowing into the battery, because the battery voltage is below the set point. The charger senses this and sources maximum current to try to force the battery voltage up.During the current limit phase, the charger must limit the current to the maximum allowed by the manufacturer (shown as 1c here) to prevent damaging the batteries.About 65% of the total charge is delivered to the battery during the current limit phase of charging. Assuming a 1c charging current, it follows that this portion of the charge cycle will take a maximum time of about 40 minutes.The constant voltage portion of the charge cycle begins when the battery voltage sensed by the charger reaches 4.20V. At this point, the charger reduces the charging current as required to hold the sensed voltage constant at 4.2V, resulting in a current waveform that is shaped like an exponential decay.The constantly decreasing charge current during the constant-voltage phase is the reason that the Li-Ion charge time is nearly two hours, even though a 1c (maximum)charging current is used (this means that delivering the final 35% of the charge takes about twice as long as the first 65%).To understand why this is true, it must be remembered that every real cell contains an internal ESR (Equivalent Series Resistance), and the voltage that the charger senses across the battery is influenced by the ESR (see Figure 6).The voltage measured at the terminals of the battery is the sum of the voltage drop across the ESR and the cell voltage. The battery is not fully charged until the cell volt-age is 4.2V with only a minute current flowing into it (which means the drop across the internal ESR is negligible, and the actual cell voltage is 4.2V).During the 1c current limit charge phase, the battery reaches 4.2V with only about 65%of charge capacity delivered, due to the voltage drop across the ESR. The charger must then reduce the charging current to prevent exceeding the 4.2V limit, which results in the decreasing current as shown in Figure 5.V BAT I CHG =()X V C +ESR V ESR =I CHG X ESRV ESRV BAT =V C +FIGURE 6. BATTERY EQUIVALENT CIRCUITSingle-Cell 150 mA ChargerWhile a maximum charging current of 1c is allowed for Li-Ion, charging at a lower rate is also possible (with a correspondingly longer charge time). The design example pre-sented next shows a simple solution for slow charging a single Li-Ion cell.Figure 7 shows the schematic of a battery charger that was designed to recharge the Li-Ion battery in a portable stereo. The customer specification for the charger was 150 mA (minimum) charging current in the current-limit charge mode, and a voltage set point of 4.200V +/- 0.025V in the constant voltage charge mode.An LP2951 regulator was selected because it has an output voltage that is very stable over temperature. Also, the LP2951 has built-in current limiting that prevents the output current from exceeding 160 mA (typical), and the part is fully protected with thermal shutdown and short-circuit protection.The LP2951 is set for an output voltage of 4.20V using the resistors shown (the trimpot is required because of the tight tolerance specification).When the battery voltage is below 4.2V, the LP2951 will source maximum current (typi-cally 160 mA) in an attempt to force the battery voltage up to 4.2V (this is the current limit phase of the charge cycle).Once the battery reaches 4.2V, the LP2951 will cut back the charging current as required to hold the battery voltage at 4.2V (this is the constant voltage portion of the charge cycle).The large resistor values used in this design are necessary to keep the "OFF" current drain below 2µA, and a 330pF capacitor is needed to prevent instability due to noise at the high-impedance feedback node.A blocking diode is used at the output of the LP2951 to prevent battery current fromflowing back into the LP2951 output pin if the input power source is removed.6-10VDCGNDLI-ION CELLFIGURE 7. SINGLE CELL LI-ION CHARGER3-Cell, 3A Charger Using the LP2952Figure 8 shows a design which was developed for a customer who needed to charge a 3-cell Li-Ion battery with a maximum of 3A.The set point voltage for the charger was specified as 12.60V, with a required precision of better than +/-1% over temperature.The design topology selected was a Low Dropout (LDO) regulator using the LP2952 as the controller and a D45H5 pass transistor to supply the 3A of current.The LP2952A is a precision LDO regulator which is rated for up to 250 mA of load cur-rent, and has a reference voltage specification limit of +/- 1.2% (room temperature) on "A" grade parts.In this design, U1 is used as a current sink for the base drive current of Q1. This base current flows through U1 (to ground) through R2.The current through U1 drives the base of Q1, which will source as much current as it can to try to bring the output up to the set voltage. This means the DC input source must be current limited so that the maximum charging current does not exceed the limit that the battery can safely handle (3A in this design).FIGURE 8. 3-CELL, 3A CHARGER USING THE LP2952。

UPS的基本知识一、UPS的概况1、UPS的概念Uninteruptible Power System的英文字首简称为UPS,即我们所说的不间断电源系统,依照字面上的解释即为电力系统停止供电时,在极短的时间内取代原有的电力设备,继续供电给负载系统使用;其工作原理：首先在正常时利用整流装置将交流输入整流成直流电力,然后一路对蓄电池充电,一路籍以将直流电力供给逆变器,逆变器将直流电力转换成稳定的交流电力输出经静态开关装置供给负载使用;当输入电力中断时,由储存在蓄电池内的直流电力供应逆变器工作转换成交流电力供负载使用;待市电完成供电准备后,才停止由蓄电池输出转换;二、UPS的组成概要依UPS内部构造可分为：电池组、充电器、逆变器及静态开关;1、电池组UPS所用的电池种类相当多,其差别在于极板材质、构造及电解液成份的不同,目前广泛UPS采用的为铅酸免加水电池,其优点在于重量轻、寿命长;电池容量单位为安培/小时Ah,数值越大则表示电池的容量越大,一般UPS标准放电时间在满载状态下最长不超过15分钟,若使用者欲延长放电时间则需另外加长效型充电电路来使用,由于电池为UPS市电中断后的电力来源,故其电池的品质及可靠度是不容忽视的,所以电池的品牌亦是选择UPS的指标,最好能尽量选世界知名品牌;2、充电器电池充电器经由变压器与市电隔离,对电池充电及提供逆变器电力,此电源需有足够的容量,但又必需有一定限流装置电路来保护电池的寿命,一般而言,对已耗尽电力的电池进行充电,将花费其放电时间常数的 8～10倍才能回充至额定压的80％,故标准型小容量在线式每放一次电需8小时以上的充电时间才能恢复电力;3、静态开关静态开关可由两个单向可控硅组成,以可控硅的高速开关特性来补偿输出继电器触点跳接时间,使AC与INV转换时,转换时间小于5ms,因为继电器的跳接时间不能满足UPS负载的要求电脑允许断电的最短时间小于6ms;4、逆变器逆变器是一种电力转换电路,它所担任的工作是将直流电源转换成一般的交流电,在UPS领域内利用整流器将交流电力整流成直流电力,然后再经逆变器转换成交流电力,即所谓的AC-DC-AC,使输出电源更为纯净,其具备如下功能：1反转：将整流器及电池组所供应的直流电源换成交流电源,波形失真小于5％;2稳定：保持交流输出电压再负载能接受之范围内2％,频率漂移则％;3限制：本身具有过电流感,当超载时用于保护自身和负载;三、UPS的作用和特点1、UPS的作用1市电中断的情况下,能利用自身所带的蓄电池通过逆变电路将直流电转换为220V交流电给计算机及网络系统供电,保证计算机及网络系统能正常运转;2对市电有稳压作用,能在电网电压波动时稳定电压;3能抑制电网的电力谐波干扰、电压瞬间跌落、高压浪涌、电压波形畸变、电磁干扰等电力污染,为计算机及其它设备提供电压稳定、波形纯正的电力供给,保证计算机及网络系统的正常工作和数据不受干扰;2、UPS的特点1高可靠性系统应具有能提供连续提供高质量的UPS逆变电源的供电能力;这就意味着,在UPS供电系统的运行中,既不允许出现任何瞬间供电中断／停电事故,也不允许出现由普通的市电经交流旁路直接向用户负载供电的情况;为此,要求UPS供电系统应满足如下要求：——允许在UPS逆变电源连续供电的条件下,执行不停电的维护和检修操作;——万一在用户设备端出现短路故障时,应将故障的影响缩小到尽可能小的范围;2高抗干扰性UPS供电系统能使互联网设备获得高“可利用率”,并可为其创造优良的运行环境;大量的运行实践表明：电源干扰问题是造成互联网设备的“可利用率”下降的重要原因之一;在此需说明的是：电源干扰不仅来源于普通的市电电网,它还来源于设计不完善的UPS本身及用户的互联网设备本身;这是因为配置在IDC和MDC机房内的服务器、磁盘阵列机和交换机等均内置有开关电源,这种整流滤波型非线性负载会向UPS供电系统反射3～23次低次谐波干扰,可能带来降低话音质量的恶果;实践证明,过大和过频地出现电源干扰,轻者会导致互联网的传输速率下降,网络服务器的数据丢包率增大等隐性故障,从而导致互联网设备被迫进入“降额使用”状态,严重时会导致网络瘫痪;由此可见,高速信息网络技术的迅猛发展,对UPS 供电系统所能提供的电源质量提出更为严格的要求;3具有防雷击、抗高能浪涌的功能雷击、闪电及电网上的高能浪涌严重威胁UPS系统和计算机网络的安全;如无相应的保护措施,将造成UPS系统及计算机网络的硬件和软件的损坏;UPS应具有这方面的保护电路,其指标应符合国家及国际安规标准;4过载能力强由于计算机等负载属于整流型负载,在启动时往往有较大的瞬态冲击电流,如果UPS的过载能力弱,有可能造成严重后果导致系统不能正常安全运行;5智能化监控在UPS和计算机/网络之间建立起双向通信监控管理功能;利用监控软件监控管理UPS 的运行、操作;当市电中断或UPS电池低电位时,监控软件可做到将计算机中的数据自动安全存盘、系统安全关机然后关闭UPS,避免因电力突然中断而造成操作系统的损坏和数据资料的损失,以实现数据的完整性保护;四、UPS的分类1、按工作方式分1后备式OFF-LINE或STAND-BYUPS当市电正常时由市电给负载设备供电,并给蓄电池浮动充电;当市电电压波动超过规定值时时启动逆变电路将电池的直流电转换为稳定的交流电输出,给负载供电;后备式UPS平时由于是由市电直接给负载供电,所以无法消除市电电网上存在的浪涌、尖峰、频率漂移等电气污染,而且容量比较小;但是它的技术简单,成本较低,价格相对低廉,用于许多对电压稳定性要求不高的场合;2在线式ON-LINEUPS在线式UPS一直使其逆变器处于工作状态,市电正常时它是首先通过电路将市电交流电转换为直流电,再通过逆变器将直流电转换为正弦波交流电给负载供电,在供电情况下还能对输出进行稳压及防止电磁干扰,而且还通过充电电路给蓄电池浮动充电;当停电时,则使用电池的直流电,所以逆变器不存在切换时间,所以适用于对电源有较高要求的场合;3在线互动式HYBRIDUPS这是一种智能化的UPS,除具有在线式UPS的功能外,还可以自动侦测市电的电压,可以提供高精度的正弦波交流电输出;在线互动式UPS 还具有与计算机进行通讯的功能,有的还可以连接互联网,可以通过网络对UPS 进行管理,而且可以根据计算机及网络系统的工作状况自动调整UPS本身的工作状况和输出状况,并且在UPS 出现故障时,可以通知计算机系统,启动冗余的备用电源,所以称之为智能型UPS;一般用于网络系统中的服务器、路由器和大型骨干网的交换机以及部分工作站等对电源要求较高的场合;它将大大提高计算机系统的可靠性;2、按输入输出分1单相输入单相输出单进单出应用于10KVA 以下,后备式、在线交互式、在线式等小容量；2三相输入单相输出三进单出应用于10KVA以上在线式；3三相输入三相输出三进三出应用于20KVA以上在线式大容量;3、按功能分可分为普通UPS、工业UPS、电力专用UPS、通信专用UPS;五、UPS电源的工作原理UPS主要分为两大类三种形式：一类是后备式,另一类是在线式,还有一种介于两者之间的在线互动式;这是在线式UPS的原理图,主要由整流器、逆变器、静态转换开关和后备电池组成.输出的交流电源是经过逆变器重新产生,其电压、波形频率由UPS本身控制,具有稳压、稳频、净化和不间断等功能;后备式在线式在线互动式工作方式：正常运行方式不断电系统的供电原理是当市电正常时,机器会将市电的交流电转换为直流电,而后对电池充电,以备电力中断时使用；这里跟各位强调的是不断电系统并不是停电时才会动作,像是遇到电压过低或过高、瞬间突波等,足以影响设备正常运转的电力品质时,不断电系统均会动作,提供设备稳定且干净的电力;当市电正常供电时,市电经滤波回路后,分为两个回路同时动作,其一是经由充电回路对电池组充电,另一个则是经整流回路,作为逆变器的输入,再经过逆变器的转换提供电力给负载使用；由此可知,在线式不断电系统的输出完全由逆变器来供应,因此不论市电电力品质如何,其输出均是稳定而不受任何影响;电池工作方式一旦市电发生异常时,将储存于电池中的直流电转换为交流电,此时逆变器的输入改由电池组来供应,逆变器持续提供电力,供给负载继续使用,达到不断电的功能;不断电系统的电力来源是电池,而电池的容量是有限的,因此不断电系统不会像市电一般无限制的供应,所以不论多大容量的不断电系统,在其满载的的状态下,其所供电的时间必定有限,若要延长放电时间,须购买长时间型不断电系统;旁路运行方式当在线式UPS超载、旁路命令手动或自动、逆变器过热或机器故障,UPS一般将逆变输出转为旁路输出,即由市电直接供电;由于旁路时,UPS输出频率相位需与市电频率相位相同,因而采用锁相同步技术确保UPS输出与市电同步;旁路开关双向可控硅并联工作方式,解决了旁路切换时间问题,真正做到了不间断切换,控制电路复杂,一般应用在中大功率UPS上;如果在过载时,必须人为减少负载,否则旁路短路器会自动切断输出;旁路维护方式当UPS进行检修时,通过手动旁路保证负载设备的正常供电,当维修操作完成后,重新启动UPS, UPS 转为正常运行;几种UPS电源的动作方式后备式UPS在市电正常时直接由市电向负载供电, 当市电超出其工作范围或停电时通过转换开关转为电池逆变供电;其特点是：结构简单,体积小,成本低,但输入电压范围窄,输出电压稳定精度差,有切换时间,且输出波形一般为方波;在线式UPS在市电正常时,由市电进行整流提供直流电压给逆变器工作,由逆变器向负载提供交流电,在市电异常时,逆变器由电池提供能量,逆变器始终处于工作状态,保证无间断输出;其特点是,有极宽的输入电压范围,无切换时间且输出电压稳定精度高,特别适合对电源要求较高的场合,但是成本较高;目前,功率大于3KVA的UPS几乎都是在线式UPS;。

新手必看，超全的电动车基本知识电池充电器篇1、电动车常用电池都有哪些？答：电动车用电池主要分为干式铅酸电池、胶体电池、锂离子电池、镍氢电池等；电压分为36V(三块12V电池),24V(两块12V电池)。

因铅酸电池价格最低，所以现在市场中几乎都是铅酸电池，且为36V的，容量为12AH，但它体积大、重量重、容量代，寿命低、寿命短。

而锂离子电池和氢电池没有上述缺点，但价格高得多，所以应用就少。

2、电池的作用及其构成？答：电池是将化学能直接转变为电能的装置。

主要部分包括正负两个电极和电解质。

3、铅酸电池的工作原理是什么？答：铅酸电池是一种使用最广泛的电池，它以海绵绵状的铅作为负极，二氧化铅作为正极，我们把这二种物质称为活性物质，用硫酸水溶液作为电解液，它们共同参与电池的电化学反应。

4、电动车用充电器有什么要求？答：电动车用充电器一般是36V铅酸电池恒流恒压充电器：主要参数为：220V交流输入，输出最高电压42V、充电电流为恒流方式2.2v，当电池电压充至42V时，则自动转为涓流方式了，且有充满指示。

5、如何对电动自行车电瓶做保养？答：电瓶在电动自行车上安装要牢固，以防骑行时电瓶受振动损害；经常清除电瓶盖上的灰尘、污物，注意保持电瓶干燥、清洁，以防电瓶自行放电；绝对不能让电瓶长期处于电量不足的状态，并且要养成每天晚上为电瓶充电的良好习惯；电动自行车刚起动时，要用脚踏助力起动，以免放电电流过大而损坏电瓶；骑行时，要注意不能让电瓶放电，过放电容易引起电瓶严重亏电，从而大大地缩短其使用权寿命。

电动自行车上一般都有没有欠压保护功能，当电瓶电量显示器只有一只显示灯亮时，应立即对电瓶进行充电，以免电瓶过放电。

6、电池盒内的连线过细会产生什么影响？答：一般电池合内的连线线径不应小于1.5mm平方，并且线端应焊接牢固，如过细或虚焊会出现控制器得到的电压偏低，骑行无力，过早欠压，线路发热等现象。

当出现上述特征时，如果整车外部电路无问题时，请打开电池盒，查看是否为此处原因引起。