-
?
?
?
?
?
?
?
?
?
?
?
?
bypass [
'bai.p
ɑ
:s ] n.
支路,道
coil [
k
?
il ] n.
卷,线圈
discharge [
dis?t
?
ɑ
:d
< br>?
] v
. & n.
放电
filter [
?filt?
] n.
滤波器,过滤器
v.
过滤
heatsink [
hi:t si?k ] n.
散热器
magnetic [ m?g'netik ] a.
磁的
mains [ mein ]
n.
电网
outlet
[?autlet] n.
电源插座
passive [ 'p?siv ] a.
被动的
,
消极的;无源的
Pulse
Rate
Modulated
(PRM)
Regulator
脉冲
速率调节器
RMS (=Root-Mean-Square)
均方根
?
?
?
?
?
?
?
?
?
?
?
pulsating [
'p
?
ls
?ti?]a.
脉动的
rated [
'reitid ] a.
标称的
ripple [ ?ripl ] n.
纹波
sample [
's?mpl]n.
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 [tr?ns'f
?
:m
?
(r),
tr
ɑ
:- ] 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
When working with
electronics, you always need power supply, a
device that transfers electric power from a source
to a load using electronic circuits.
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 typical
application of power supplies is to convert
utility's 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.
电源的主要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
inp
ut
source
voltage) and step-down (output supply voltage is
lower than input source voltage) applications.
Linear power
supplies
are
also
available
with
either
a
fixed
output
voltage
or
a
variable
output
voltage
when
using
external
biasing
.
< br>:
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: T
ransformer, which steps down
high
voltage
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.
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
——<
/p>
把电网
高压交流电转换为低压交流电;整流器
——
把交流电转换为直流电,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
coils; instead they are linked by an
alternating magnetic field created in the soft-
iron core of the transformer.
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<
/p>
1V
的电压降
V
on
,这常
被认为是二极管的“正向电压降”
< br>,若为硅二极管,大约为
0.7V
。
Bridge rectifiers are
rated by the passed maximum current and the
maximum reverse voltage they can withstand
(this must be at least three times the
supply RMS voltage so the rectifier can withstand
the peak voltages).
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
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.
由电容器,或电阻器,
或电感器,
或
< br>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。对于许多电路来说,纹波电压大小
为电源电压的
10
%是合适的。
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
variable
output
voltages,
largely
simplifying
the
regulator
designs.
Most
regulators
include
some
automatic
protection from excessive current
(?overload protection?) and overheating (?thermal
protection?).
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 ne
cessary.
: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。
The
advantage
of
linear
regulators is
simple
implementation
and
minimal
parts
(just the IC
in
the
case
of
fixed
output) and low output
ripple. The major disadvantage of linear
regulators is low efficiency.
线性稳压器的优点是<
/p>
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 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).
:
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 step 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.
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
/
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(
P
RM
)调节器、一个高速开关二极管和一个电容器组
成。如图<
/p>
2
-2
所示,其中核心器件是开关晶体管和开关变压器。
By
controlling
the
amount
of
“on
time”
and
“off
time”
of
the
switches,
the
amount
of
power
delivered
to
the
transformer?s load can
be controlled. PWM regulators 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.
控制开关的打开时间和关闭时间的
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
p>
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
。
As
the
transistor
is
switched
on
and
off
the
magnetic
field
alternately
expands
and
collapses in
the
transformer
windings.
By
designing
the
transformer
with
different
secondary
turn?s
ratios,
various
amplitude
pulses
are
produced at the output of each
secondary winding. The output of each winding is
applied to high speed swi
tching
diodes and filters (capacitors or
inducers) which produce the DC output voltages of
the switch mode power supply.
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。