Transcript Diode

‫بسم هللا الرحمن الرحيم‬
‫مفردات المنهاج‬
week
Theoretical syllabus
𝟏st
Power electronic, electronic components which used in high power
control (power diodes, thyristor and power transistors) prevision of
single phase rectifier circuits.
2𝑛𝑑
Three –phase rectifier circuits by using diodes , output voltage
waveform, diode current waveform, output voltage equation in case of
resistance load.
3rd
Using the transistor as switch, region of operation, transistor as a
switch (cutoff and saturation) .
4𝒕𝒉
Power transistor in off and on state , improvement of off and on time by
using speed up capacitance , practical problem.
5𝒕𝒉
Unijunction transistor, construction, theoretical operation, using the
transistor as relaxation oscillator practical example .
6𝒕𝒉
Operational amplifier , description of operational amplifier as aspartate
component , zero detector, comparator .
7𝒕𝒉
The use of op-amp as a stable multivibrator and a monostable
multivibrator , photo conduction cells , photo diodes .
week
Theoretical syllabus
8th
Light-emitting diodes (LED), photo transistors, the use of optical
comparator in power Electronic circuits .
9𝑡ℎ
Thyristor, construction, characteristic, curve for a thyristor, thyristor
conduction in forward biasing, thyristor family, thyristor representation
as a double transistor circuit .
10𝑡ℎ
Thyristor conduction methods, conduction throw the gate minimum gate
current causing conduction, conduction time ,conduction due to high
forward voltage rectifier (dv/dt)
11𝒕𝒉
DIAC,TRIAC characteristics, practical applications, thyristor , triggering
methods, triggering on DC and AC current, pulse triggering types .
12𝒕𝒉
Thyristor triggering circuit, DC and AC triggering circuits .
13𝒕𝒉
Pulse current triggering circuit , relaxation oscillator , zero detector ,
comparator , with astable and monostable multivibrators (op-amp ) .
7𝒕𝒉
Thyristor general application introductory , AC to DC inverter DC to AC
inverter , DC to DC invertor , AC to AC inverter , phase controlled half
wave
week
Theoretical syllabus
𝟏𝟓𝒕𝒉
Half controller full wave rectifier fully controlled ,resistance and
inductance load generated wave forms , output voltage equation for
free wheeling diode.
𝟏6𝒕𝒉
Regenerating fully controlled inverters, examples, Dc motor speed
control .
𝟏7𝒕𝒉
Three –phase inverters, output voltage wave form with , triggering
pulses and equations .
𝟏8𝒕𝒉
Thyristor protection from the high rate change in current and voltage ,
protection from the transient change in source voltage, fully protection
circuit from all possible faults due to current and voltage.
𝟏9𝒕𝒉
DC to AC inverters methods of forcing the thyristor to get off.
20𝒕𝒉
Parallel and series inverter, single and three phase , control methods in
charging frequency and voltage output waveform .
21𝒕𝒉
Inverter application, emergency power supply , single phase DC motor
speed control .
‫مفردات المنهاج‬
22𝒕𝒉
Three phase motor control by using a constant ratio of variation
frequency and voltage.
23𝒕𝒉
Choppers , DC to DC inverter frequency constant , line constant .
24𝒕𝒉
Types of choppers, DC motor speed control .
25𝒕𝒉
AC to AC inverter, single phase voltage regulator, three phase voltage
regulator .
26𝒕𝒉
General application on single and three induction motor speed control
due to the change in stator voltage , using the closed loop feed back
circuit to control the slippery rings of AC motor .
27𝒕𝒉
Cyclic inverter ,AC to DC cyclic inverter, DC to DC cyclic inverter .
28𝒕𝒉
AC to AC cyclic inverter control block diagram .
29𝒕𝒉
Using amplitude modulation for speed control .
30𝒕𝒉
Using polar transistor for AC motor speed control .
‫أألسبوع األول‬
‫االختبار القبلي‬
Key Answer
:
+
A
IAK
anod
e
+
-
VBR
-VAK
VAK
VB
-
K
Cut in
voltage=0.7 V
cathod
e
IC
Saturation
IB3
Active
region
IB2
IB1
IB=0
Cut off region
VCE
Systems based on power electronics, however, suffer
from the following disadvantages :
• Power-electronic converter circuit have a tendency
to generated harmonics in the supply system as
well as in the load circuit .
• Ac to dc and ac to ac converters operate at a low
input power factor under certain operating
conditions . In order to avoid a low pf , some special
measures have to be adopted .
• Power-electronic controllers have low overload
capacity . These converters must, therefore, be
rated for taking momentary overloads. As such,
cost of power electronic controller may increase .
• Regeneration of power is difficult in power
electronic converter system .
Main Power
source
Control
unit
Digital
circuit
Power Electronic
circuit
command
Feedback signal
Load
Power electronic element
Today 's power semiconductor devices are almost
exclusively based on silicon materials and can be
classified as follows :
1- Diodes .
2- thyristor or silicon controlled rectifiers (SCR) .
3-Triac and Diac .
4- Gate turn –off thyristor (GTO) .
5- Bipolar junction transistor (BJT) .
6- Mos –controlled thyristor .
And other devices
Maximum rating of power semiconductor device
S.No.
Device
Circuit
symbol
Voltage
/current
rating
Upper
0perating
freq. (kHz)
1.
Diode
5000 V/5000A
1.0
2.
Thyristors
(a) SCR
7000V/5000A
1.0
S.No.
3-
Device
Circuit
symbol
Voltage
/current
rating
Upper
0perating
freq. (kHz)
B-LASCR
6000 V / 3000A
C- GTO
5000 V/3000 A
2.0
D- Triac
1200 V / 400 A
0.50
1.0
Transistors
A-BJT
1400 V/400 A
10.0
Q :- What is the structural difference
between the diode and the SCR ?
A power electronic system consists of one or more
power electronic converters . A power electronic
converters is made up of some power semiconductor
devices controlled by integrated circuit .the switching
characteristics of power semiconductor devices
permit a power electronic converter to shape the
input power of one form to output power of some other
form. Static power converters perform these functions
of power conversion very efficiency .broadly
speaking, power electronic converters (or circuit )can
be classified into six types as under :
It is provide un controlled rectification of
power and are used in applications such as
electroplating , battery charging , welding ,
power supplies, freewheeling , and so on . It
is mad in different Shapes , sizes and
different rating .
o choose these diodes it is important to take : P.I.V {peak. inverse. Voltage } forward current
and maximum temperature in to account.
• Diode symbol and volt – ampere characteristic is show below :
A
+
𝒏−
𝒏+
Anode
𝑷+
+
anode
-
cathode
+
-
Drift region
J1
substrate
-
K
IAK
VBR
VAK
-VAK
VB
Cut in
voltage=0.7 V
Vd
Vs
t
A.C
I/P
VS
I
RL
VL
π ₂π
Vin=Vm sin wt
Where w= 2πf (angular frequency )
Vm= peak voltage
f=frequency (Hz)
Using Kirchhoff ‘s low for the circuit shown
above :
𝒊=
𝑽𝒊𝒏
(𝑹𝒇 +𝑹𝑳 )
𝒊=
𝑽𝒎 sin 𝝎𝒕
(𝑹𝒇 +𝑹𝑳 )
i=Im sinwt
Rf =forward diode resistance
The DC component of rectifier :
𝟏 𝑻
𝑰𝒅𝒄 = 𝟎 𝑰(𝜽) 𝒅𝜽
𝑻
𝟐𝝅
𝟏
𝑰𝒅𝒄 =
𝑰(𝜽) 𝒅𝜽
𝟎
𝟐𝝅
𝝅
𝟐𝝅
𝟏
=
𝑰𝒎 𝐬𝐢𝐧 𝜽 𝒅𝜽 + 𝝅 𝟎𝒅𝜽
𝟎
𝟐𝝅
𝝅
𝑰𝒎
=
𝒔𝒊𝒏 𝜽 𝒅𝜽
𝟐𝝅 𝟎
𝑰𝒎
=
−𝐜𝐨𝐬 𝜽
𝟐𝝅
𝑰𝒎
=
− 𝐜𝐨𝐬 𝝅 − (− 𝐜𝐨𝐬 𝟎)
𝟐𝝅
𝑰𝒎
𝑰𝒅𝒄 =
…………..1
𝝅
The RMS component calculation:
𝑰𝒓𝒎𝒔 =
𝟏 𝑻 𝟐
𝒊 𝒅𝜽
𝑻 𝟎
𝟏
=
𝟏 𝝅
𝟐
𝟐
𝟐
𝑰
𝐬𝐢𝐧
𝜽
𝒅𝜽
𝒎
𝟐𝝅 𝟎
𝟐
=
=
𝝅 𝟏−𝐜𝐨𝐬 𝟐𝜽
𝑰𝒎
𝒅𝜽
𝟐𝝅 𝟎
𝟐
𝑰𝒎 𝟐
𝟐𝝅
𝟏
𝑰𝒎
𝟒𝝅
𝑰𝒎
𝟒𝝅
𝟏
𝟏
𝝅 − 𝟎 − 𝟐 𝐬𝐢𝐧 𝟐𝝅 − 𝐬𝐢𝐧 𝟐 ∗ 𝟎
𝟐
=
𝟏
𝟐
∗ 𝟐 𝜽 − 𝟐 𝐬𝐢𝐧 𝟐𝜽
𝟐
=
𝟏
𝟐
𝝅
𝟏
𝟐
𝟏
𝟐
………………….2
Vdc=230 V
𝑉𝑑𝑐 =
𝑉𝑚
𝜋
= 230
𝑉𝑚 = 3.14 ∗ 230 = 722.63 𝑉
PIV=722.6 V
𝐼𝑚 =
𝑉𝑚
𝑅𝐿
=
722.6
10
𝐼𝑑𝑐 =
𝑉𝑑𝑐
𝑅𝐿
=
230
10
= 72.26 𝐴
= 23 A
• Example :
• Solution :The half-wave diode rectifier uses a step-up transformer
therefore, ac voltage applied to rectifier
• Drive an equation to calculate the r.m.s
voltage component for single phase full
wave rectifier .
• Calculate the ripple factor and power
energy conversion for full wave rectifier .
• For a single – phase half – wave diode
rectifier feeding a resistive load R, find the
values of rectifier efficiency ,form factor
,voltage ripple factor .in terms of Vm .
Key Answer
Q1 :-
𝑰𝒓𝒎𝒔 =
𝟏 𝑻 𝟐
𝒊 𝒅𝜽
𝑻 𝟎
𝟏
=
𝟏 𝝅
𝟐
𝑰 𝟐 𝐬𝐢𝐧 𝜽𝟐 𝒅𝜽
𝟐𝝅 𝟎 𝒎
=
𝟐
𝑰𝒎 𝟐 𝝅 𝟏−𝐜𝐨𝐬 𝟐𝜽
𝒅𝜽
𝟐𝝅 𝟎
𝟐
𝟏
=
𝑰𝒎 𝟐
𝟐𝝅
=
𝑰𝒎 𝟐
𝟒𝝅
𝟏
∗𝟐
𝜽−
𝟏
𝐬𝐢𝐧 𝟐𝜽
𝟐
𝝅−𝟎 −
𝟏
𝟐
𝟏
𝟐
𝐬𝐢𝐧 𝟐𝝅 − 𝐬𝐢𝐧 𝟐 ∗ 𝟎
𝟏
𝟐
𝟏
=
𝟐
𝑰𝒎 𝟐
𝝅
𝟒𝝅
=
Q2 𝑃𝐶𝐸 =
𝑰𝒎
𝟐
𝑃𝑑𝑐
𝑃𝑎𝑐
=
𝑉𝑑𝑐 2
𝑅𝐿
𝑉𝑟𝑚𝑠 2
𝑅𝐿
=
𝑉𝑚 2
𝜋∗𝜋
𝑅𝐿
𝑅𝐿
∗𝑉
𝑚
4
2
= 40.5%
‫‪Reference‬‬
‫• اإللكترونيك الصناعي تأليف‪ :‬ضياء مهدي فارس ‪.‬‬
‫تأليف‪ :‬ضياء مهدي فارس ‪.‬‬
‫• االلكترونيك القدرة‬
‫‪• Power electronic By Dr.P.S.Bimbhra‬‬