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1、学习重点：（1）掌握有关电源的基本单词、词组和缩略语的基本含义及用法（2）培养阅读翻译有关电源科技文献和产品说明书的能力（3）学习科技英语中的名词化结构，掌握由动词、形容词、过去分词、动名词等派生或转化来的抽象名词,2 Power Supplies,生词bypass bai.p:s n.支路，道coil kil n.卷，线圈discharge dist:d v.&n.放电,Passage ABasics of Power Supply,filter filt n.滤波器，过滤器 v.过滤heatsink hi:t sik n.散热器magnetic mgnetik a.磁的mains mein
2、 n.电网outlet autlet n.电源插座passive psiv a.被动的,消极的；无源的pulsating plstia.脉动的rated reitid a.标称的ripple ripl n.纹波sample smpln.样品；标本v.抽取样品,smooth smu:a.平稳的，流畅的 v.使.光滑，滤波transformer trnsf:m(r),tr:-n.变压器bridge rectifier 桥式整流器magnetic field.磁场overheating 过热Pulse Width Modulated(PWM)Regulator 脉冲宽调制调节器Pulse Rate
3、Modulated(PRM)Regulator 脉冲速率调节器RMS(=Root-Mean-Square)均方根,2.课文翻译讲解,When working with electronics,you always need power supply,a device that transfers electric power from a source to a load using electronic circuits.,现在分词短语，作时间状语,同位语，进一步说明power supply,翻译：当你工作中用到电子学时，你就需要电源装置。电源是一用电路把电能从电源输送给负载的设备。,A t
4、ypical application of power supplies is to convert utilitys AC input power into regulated DC voltage(s)required for electronic equipment.Depending on the mode of operation of power semiconductors power supply can be linear or switching.,Application是动词转化 过来的名词,不定式短语作表语,过去分词短语，修饰DC voltage(s）,翻译：电源的主要
5、用途是将有效的交流输入功率转换为电子设备所需的直流电压。根据电源功率半导体器件的工作方式电源装置可以是线性或开关式的。,Linear voltage power supplies are commonly used for both step-up(output supply voltage is greater than input source voltage)and step-down(output supply voltage is lower than input source voltage)applications.Linear power supplies are also a
6、vailable with either a fixed output voltage or a variable output voltage when using external biasing.,翻译：线性稳压器常用于电压的提升（输出供电电压大于输入源电压）和降低（输出供电电压低于输入源电压）。使用外部偏置，线性稳压器也可产生恒定输出电压或可变输出电压。,The basic block of a linear power supply is shown in Figure 2-1,which includes:Transformer,which steps down high volt
7、age AC mains to low voltage AC;Rectifier,which converts AC to DC,but the DC output is varying;Filtering,which filters the DC from varying greatly to a small ripple;Regulator,which eliminates ripple by setting DC output to a fixed voltage.,翻译：线性电源可以分解为一系列基本模块，如图2-1所示，该图包括：变压器把电网高压交流电转换为低压交流电；整流器把交流电转
8、换为直流电，但是直流输出是变化的；滤波器从直流电流中滤掉变化较大的成分使之仅有小的纹波成分；稳压器消除纹波，输出固定值的直流电压。,Transformer converts the voltage from the wall outlet(mains)to a different,usually a lower voltage.The input coil is called the primary and the output coil is called the secondary.There is no electrical connection between the two coil
9、s;instead they are linked by an alternating magnetic field created in the soft-iron core of the transformer.,翻译：当一个小的电压V正向加到二极管时，就会有一个小的电流流过，并产生一个大约为0.6V到1V的电压降Von，这常被认为是二极管的“正向电压降”，若为硅二极管，大约为0.7V。,alternating magnetic field为动名词短语,A bridge rectifier circuit is employed to produce DC output and can b
10、e made by four individual diodes or a single chip,on which an array of four diodes is integrated,for full wave rectification,and also can be made by a single diode yielding a half wave(pulsating)output.1.4V is used up in the bridge rectifier because each diode uses 0.7V when conducting and there are
11、 always two diodes conducting.,翻译：桥式整流器线路用于产生直流输出，它可以由四个单个的二极管或集成有四个二极管的单个芯片构成以用于全波整流，也可用产生半波（脉冲）输出的一个二极管构成。1.4伏电压被消耗在桥式整流器中，因为在导通时每个二极管用掉0.7伏，而在在桥式整流器中总是有两个二极管同时导通。,rectification是由动词转化来的抽象名词，pulsating 和conducting为动词转化来的动名词,Bridge rectifiers are rated by the passed maximum current and the maximum re
12、verse voltage they can withstand(this must be at least three times the supply RMS voltage so the rectifier can withstand the peak voltages).,翻译：桥式整流器是由它能通过的最大电流值和所能承受的最大反向电压（这一电压值至少是均方根电压的三倍，这样整流器才能承受住峰值电压）来标称的。,A filter,consisted of capacitors or resistors or inducers or their combinations,is used
13、to filter part of the pulses giving a smoothed DC voltage.However,filtering is not perfect and small pulses,known as ripple,are still remained.For many circuits a ripple,which is 10%of the supply voltage,is satisfactory.,翻译：由电容器，或电阻器，或电感器，或它们的组合而构成的滤波器可过滤部分脉冲而得到平滑的直流电压。然而，滤波器不是完美的，仍然存在小脉冲，常称之为纹波电压。对
14、于许多电路来说，纹波电压大小为电源电压的10是合适的。,combination是由动词转化来的抽象名词，filtering为动词转化来的动名词,A simple voltage regulator for low current power supplies can be made up of a resistor and a Zener diode connected in reverse.But nowadays,many types of voltage regulator ICs can be available with fixed(typically 5,12 and 15V)or
15、 variable output voltages,largely simplifying the regulator designs.Most regulators include some automatic protection from excessive current(overload protection)and overheating(thermal protection).,翻译：用于低电流电源，稳压器可以简单地由一个电阻和一个反向连接的齐纳二极管构成。但是目前，许多类型的集成稳压器的输出可以为固定值（通常为5伏，12伏和15伏）或可变值，大大简化了设计过程。大部分稳压器都具
16、有一些过电流(过载保护)和过热（热保护）自动保护功能。,Many of the fixed voltage regulator ICs has 3 leads and look like power transistors,such as the 7805+5V 1A regulator.They include a hole for attaching a heatsink if necessary.,The advantage of linear regulators is simple implementation and minimal parts(just the IC in the
17、 case of fixed output)and low output ripple.The major disadvantage of linear regulators is low efficiency.,翻译：许多固定输出的集成稳压器有3根引线，看起来像功率晶体管，例如7805+5V 1A稳压器。它们包含一个孔，如果必要的话，在此孔上可以附加一个散热片。,翻译：线性稳压器的优点是实现简单、部件体积小（就固定输出而言恰好是集成电路）和输出纹波低。线性稳压器的主要缺点是效率低。,Switch mode power supply are continuously switching on
18、and off with high frequency from 20 kHz to several MHz to provide the transfer of electric power via energy storage components(inductors and capacitors).,翻译：开关式电源装置连续不断地以20千赫至几兆赫的高频率进行开关操作，通过储能元件（电感器和电容器）提供电能的转换。,A basic switch mode power supply is consisted of a rectifier,a switching transistor,a s
19、tep up/down transformer,and a switching controller-Pulse Width Modulated(PWM)Regulator or Pulse Rate Modulated(PRM)Regulator,a high speed switching diode,and a capacitor,as shown in Figure 2-2,in which the heart is the switching transistor and switching transformer.,翻译：一套基本的开关式电源由一个整流器、一个开关晶体管、一个升压/
20、降压变压器、一个开关控制-脉冲宽度调制（PWM）调节器或脉冲速率调制（PRM）调节器、一个高速开关二极管和一个电容器组成。如图2-2所示，其中核心器件是开关晶体管和开关变压器。,Figure 2-2 a basic schematic of a switch mode power supply,By controlling the amount of“on time”and“off time”of the switches,the amount of power delivered to the transformers load can be controlled.PWM regulator
21、s vary the“on”or conduction time of the switching transistor,while the PRM regulator varies the modulation rate(frequency)at which the switching transistor is turned off and on,and these regulations are achieved by sampling the DC output voltage and comparing it to a reference voltage.,翻译：控制开关的打开时间和
22、关闭时间的总数，可以控制传递到变压器负载上的电量。PWM改变开关晶体管打开或导通的时间，而PRM改变调制速率，此调制速率是开关晶体管关闭和开启的速率（频率），这些调节是把采样到的直流输出电压和参考电压相比而达到的。,cntrollingsamplingcomparing均为动名词短语动名词虽起名词的作用，但仍具有动词的若干特点，可以有宾语和状语,As the transistor is switched on and off the magnetic field alternately expands and collapses in the transformer windings.By d
23、esigning the transformer with different secondary turns ratios,various amplitude pulses are produced at the output of each secondary winding.The output of each winding is applied to high speed switching diodes and filters(capacitors or inducers)which produce the DC output voltages of the switch mode
24、 power supply.,翻译：随着晶体管的打开和关闭，变压器绕组中的磁场交替增强和减弱。用设计具有不同的次级匝数比的变压器，就会在每个次级绕组的输出端产生不同的幅度脉冲。每个绕组的输出端连接到高速开关二极管和滤波器（电容器或电感器）上，以产生出开关式电源的直流输出电压。,A switch mode power supply offers three main advantages over a conventional linear power supply:1)high efficiency&less heat generation2)tighter regulation3)small
25、er size and weight.,The disadvantage of switching regulators is complexity,as several external passive components are required on board.Output voltage ripple is another disadvantage,which is generally handled with bypass capacitance near the supply and at the load.,翻译：图2-2 开关式电源装置的基本原理图与传统的线性电源相比，开关
26、电源有三个主要优点：1）高效低热2）更为严密的调节3）尺寸小、重量轻,翻译：复杂性是此开关稳压器的一个缺点，因为板上需要几个外部附加元件。另一个缺陷是输出电压有纹波，它一般是用电源和负载附近的旁路电容来处理的。,3.疑难解析,1).A simple voltage regulator for low current power supplies can be made up of a resistor and a Zener diode connected in reverse.对于低电流电源，简单的稳压器可以由一个电阻和一个反向连接的齐纳二极管构成。be made up of 意为“由.组成
27、/构成”，相当于be composed of或consists of。比较：be made(out)of,be made from 均表示“由.制成”;be made into 表示“被制成.”;be made in(后接地点)表示“产于.”。,2)Many of the fixed voltage regulator ICs have 3 leads and look like power transistors,such as the 7805+5V 1A regulator.They include a hole for attaching a heatsink if necessary
28、.许多固定电压积成稳压器有3根引线,看起来像功率晶体管，例如7805+5V 1A稳压器。它们包含一个孔，如果必要的话，在此孔可以附加上一个散热片。(1)such as 意为：“如、例如”相当于for example,但表示“举例说明”时只能用 for example，后面接完整的句子，such as后通常接名词或短语，不接句子。(2)if necessary 是一个省略表达式，相当于if it is necessary 省略了主语和谓语it is。,4 语法应用,科技英语大量使用名词化结构名词化结构是英语正式语体的特征之一。名词化结构的中心词一般是由动词或形容词派生或转化来的抽象名词,也有名词化的过去分词，名词化的动名词，名词化的数词，名词化词组，其意义往往抽象,但有时又指具体事物,并且其结构成分之间关系复杂。其中由行为动词派生或转化来的抽象名词往往由动词加上-m e n t，-s i o n，-x i on，-me n t，-a l i c e，-e n c e等后缀构成，这类抽象名词在科技英语中很常见。,
