SIM UNIVERSITY
SCHOOL OF SCIENCE AND TECHNOLOGY
VOLTAGE/CURRENT DISTORTION
IN SWITCH-MODE POWER
SUPPLIES & FILTERING,
COST AND BENEFITS
STUDENT
SUPERVISOR
PROJECT CODE
: M0605333
: A.I. MASWOOD
: JUL2009/ENG/021
A project report submitted to SIM University
In partial fulfilment of the requirements for the degree of
Bachelor of Engineering (or Bachelor of Electronics)
May 2010
ABSTRACT
The author’s project involves the designing and building of the simulation
model of the Converter with the help of the PSIM circuit simulator. There are
different types of converters such as buck converter, boost converter, flyback
converter and forward converter available for different purposes. The report initially
covers a brief introduction about the converters, information about the converters
available on the market and the analysis of relevant technologies. It then proceeds to
document the development of the simulation model in the software, to achieve the
goal of the project title “Voltage/Current Distortion in Switch-Mode Power Supplies
& Filtering, Costs and Benefits”. Finally, the report includes some suggestions for
further improvement of the simulation model.
i
ACKNOWLEDGEMENT
The author would sincerely express his thanks to the following people for their
continued help, support and guidance throughout this project. The work presented in
this report would not been possible without them:

Dr. Maswood Ali I, author’s project supervisor from Nanyang Technological
University (NTU), for all his immensely useful suggestions, ideas, and time
on power electronics. His encouragement, guidance and advice were
invaluable in keeping the project on track.

The author’s friends Mr. Loo Soon Koon, Mr. Alagen and Mr. Koo Hong
Tak for the sharing of their knowledge and guidance for the improvement for
this project throughout the duration of this project.

Finally, author’s biggest thank you goes to his parents for their unlimited
understanding, guidance and support.
Words can never describe how grateful the author is to those mentioned above.
ii
TABLE OF CONTENTS
PAGE
ABSTRACT
i
ACKNOWLEDGEMENT
ii
LISTS OF FIGURES
iii
LISTS OF TABLES
vi
LIST OF SYMBOLS
vii
CHAPTER 1
INTRODUCTION
1
1.1
PROJECT BACKGROUND
1
1.2
PROJECT OBJECTIVE
2
1.3
OVERALL PROJECT OBJECTIVE
2
1.4
PROPOSED APPROACH
2
1.5
SKILLS REVIEW
3
CHAPTER 2
LITERATURE REVIEW
5
2.1
IEEE STANDARDS (STD-519)
5
2.1.1
VOLTAGE DISTORTION
5
2.1.2
CURRENT DISTORTION
6
2.2
2.3
POWER SUPPLY
9
2.2.1
LINEAR MODE POWER SUPPLY
9
2.2.2
SWITCH MODE POWER SUPPLY
10
CIRCUIT DESIGN AND SOFTWARE OVERVIEW
11
2.3.1
CIRCUIT DESIGN OVERVIEW
11
2.3.1.1 DESCRIPTION OF DIFFERENT
COMPONENTS USED
12
-
AC SOURCE
INDUCTOR
CAPACITOR
LINE FILTER
STEP-DOWN TRANSFORMER
DIODE
12
12
13
14
15
16
-
FULL-WAVE BRIDGE RECTIFIER
GROUND
2.3.1.2 DIFFERENT TYPES OF FILTERS
-
(1) RL FILTER DESIGN
(2) LC FILTER DESIGN
(3) RC FILTER DESIGN
(4) REACTANCE CALCULATION
(5) COMPARISON OF FILTERS
(6) COSTS OF COMPONENTS
2.3.1.3 DIFFERENT TYPES OF CONVERTERS
2.3.2
BUCK CONVERTER CIRCUIT
BOOST CONVERTER CIRCUIT
FLYBACK CONVERTER CIRCUIT
FORWARD CONVERTER CIRCUIT
17
17
18
20
21
22
23
24
25
27
28
29
31
33
SOFTWARE OVERVIEW
35
2.3.2.1 PSIM
35
2.3.2.2 LT SPICE
37
CHAPTER 3
SIMULATION TESTING AND RESULTS
38
3.1.1
CIRCUIT DESIGN TESTING
38
3.1.2
RESULTS
41
CHAPTER 4
PROBLEMS ENCOUNTERED AND SOLUTIONS
47
CHAPTER 5
CONCLUSION
50
5.1
FUTURE WORK
50
5.2
SUMMARY
51
5.3
REFLECTION
52
REFERENCES FROM INTERNET
54
REFERENCES FROM BOOKS
56
APPENDIX A
-
GANTT CHART FOR PROJECT PLANNING
57
APPENDIX B
-
FLOW DESIGN OF THE FINALIZED SIMULATION MODEL
STAGE 1
STAGE 2
STAGE 3
STAGE 4
STAGE 5
STAGE 6
STAGE 7
APPENDIX C
-
RESULTS OF THE FINALIZED SIMULATION MODEL
STAGE 1
STAGE 2
STAGE 3
STAGE 4
STAGE 5
STAGE 6
STAGE 7
APPENDIX D
-
-
62
63
64
65
66
68
69
DESIGN OF OTHER FILTERS SIMULATION MODEL
LC FILTER MODEL
RC FILTER MODEL
LR FILTER MODEL
APPENDIX E
58
58
59
59
60
60
61
71
71
71
RESULT OF OTHER FILTERS SIMULATION MODEL
LC FILTER RESULTS
RC FILTER RESULTS
LR FILTER RESULTS
72
73
74
LIST OF FIGURES
PAGE
FIGURE 1
:
BLOCK DIAGRAM OF A COMPLEX SMPS
3
FIGURE 2
:
EXAMPLE OF A LINEAR POWER SUPPLY
9
FIGURE 3
:
EXAMPLE OF A SWITCH-MODE POWER SUPPLY
10
FIGURE 4
:
EXAMPLE OF A PASSIVE FILTER APPLICATION
19
FIGURE 5
:
R-L FILTER DESIGN
20
FIGURE 6
:
L-C FILTER DESIGN
21
FIGURE 7
:
R-C FILTER DESIGN
22
FIGURE 8
:
BUCK CONVERTER CIRCUIT
28
FIGURE 9
:
DESIRED OUTPUTS OF BUCK CONVERTER CIRCUIT
29
FIGURE 10
:
BOOST CONVERTER CIRCUIT
29
FIGURE 11
:
DESIRED OUTPUTS OF BOOST CONVERTER CIRCUIT
30
FIGURE 12
:
FLYBACK CONVERTER CIRCUIT
31
FIGURE 13
:
DESIRED OUTPUTS OF FLYBACK CONVERTER CIRCUIT
32
FIGURE 14
:
FORWARD CONVERTER CIRCUIT
33
FIGURE 15
:
DESIRED OUTPUTS OF FORWARD CONVERTER CIRCUIT
34
FIGURE 16
:
SIMULATION ENVIRONMENT OF PSIM
36
FIGURE 17
:
EXAMPLE OF HARMONICS IMAGE ( FFT )
50
FIGURE 18
:
FIRST STAGE OF DESIGN
58
FIGURE 19
:
SECOND STAGE OF DESIGN
58
FIGURE 20
:
THIRD STAGE OF DESIGN
59
FIGURE 21
:
FOURTH STAGE OF DESIGN
59
FIGURE 22
:
FIFTH STAGE OF DESIGN
60
FIGURE 23
:
SIXTH STAGE OF DESIGN
60
FIGURE 24
:
SEVENTH STAGE OF DESIGN
61
FIGURE 25
:
AC SOURCE WAVEFORM @ 230VAC
62
FIGURE 26
:
CURRENT WAVEFORM FLOWING THROUGH THE
CIRCUIT @ 4.6A
62
iii
FIGURE 27
:
VOLTAGE WAVEFORM ON ITS SECONDARY SIDE
OF TRANSFORMER @ 12VAC
63
FIGURE 28
:
CURRENT WAVEFORM AFTER THE SECONDARY
SIDE OF TRANSFORMER FLOWING THROUGH THE
CIRCUIT @ 0.24A
63
FIGURE 29
:
VOLTAGE WAVEFORM AFTER THE FULL-WAVE
BRIDGE RECTIFIER @ 12VDC
64
FIGURE 30
:
CURRENT WAVEFORM AFTER THE FULL-WAVE
BRIDGE RECTIFIER STILL REMAINS AS STAGE 2
@ 0.24A
64
FIGURE 31
:
VOLTAGE WAVEFORM AFTER THE FILTER
CAPACITOR WHERE RIPPLE IS BEING MINIMIZED
AND MAINTAINED @ 12VDC
65
FIGURE 32
:
CURRENT WAVEFORM AFTER THE FILTER
CAPACITOR FLOWING THROUGH THE CIRCUIT
@ 0.24A
65
FIGURE 33
:
VOLTAGE WAVEFORM AFTER THE FILTER
CAPACITOR REMAINS @ 12VDC WITH LOAD
CHANGED
66
FIGURE 34
:
CURRENT WAVEFORM AFTER THE FILTER
CAPACITOR FLOWING THROUGH THE CIRCUIT
@ 0.22A WITH LOAD CHANGED
66
FIGURE 35
:
AC SOURCE WAVEFORM REMAINS UNAFFECTED
AFTER LOAD CHANGED
67
FIGURE 36
:
CURRENT WAVEFORM AT AC SOURCE IS BEING
AFFECTED WITH LOAD CHANGED
67
FIGURE 37
:
INPUT VOLTAGE WAVEFORM TO THE BUCK
CONVERTER @ 12VDC
68
FIGURE 38
:
OUTPUT VOLTAGE WAVEFORM AFTER THE
BUCK CONVERTER @ 5VDC
68
FIGURE 39
:
AC SOURCE WAVEFORM @ 230VAC BEFORE FILTER
IS BEING IMPLEMENTED
69
FIGURE 40
:
CURRENT WAVEFORM AT AC SOURCE IS BEING
DISTORTED WHEN THIS CIRCUIT IS COMPILED
TOGETHER AND HAPPENS BEFORE FILTER IS
BEING IMPLEMENTED
69
FIGURE 41
:
FFT RESULTS OF THE CURRENT WAVEFORM AT
AC SOURCE IS BEING DISTORTED
69
FIGURE 42
:
AC SOURCE WAVEFORM @ 230VAC REMAINS
UNCHANGED AFTER FILTER IS BEING IMPLEMENTED
70
iv
FIGURE 43
:
CURRENT WAVEFORM AT AC SOURCE IS BEING
CLEANED UP AFTER FILTER IS BEING IMPLEMENTED
70
FIGURE 44
:
FFT RESULTS OF THE CURRENT WAVEFORM AT AC
SOURCE IS BEING CLEANED UP
70
FIGURE 45
:
LC FILTER SIMULATION MODEL
71
FIGURE 46
:
RC FILTER SIMULATION MODEL
71
FIGURE 47
:
LR FILTER SIMULATION MODEL
71
FIGURE 48
:
AC VOLTAGE WAVEFORM @ THE SOURCE AFTER LC
FILTER IS IMPLEMENTED
72
FIGURE 49
:
AC CURRENT WAVEFORM @ THE SOURCE IS BEING
CLEANED UP AFTER LC FILTER IS IMPLEMENTED
72
FIGURE 50
:
FFT OF THE AC CURRENT WAVEFORM @ THE SOURCE
72
FIGURE 51
:
AC VOLTAGE WAVEFORM @ THE SOURCE AFTER RC
FILTER IS IMPLEMENTED
73
FIGURE 52
:
AC CURRENT WAVEFORM @ THE SOURCE IS BEING
CLEANED UP AFTER RC FILTER IS IMPLEMENTED
73
FIGURE 53
:
FFT OF THE AC CURRENT WAVEFORM @ THE SOURCE
73
FIGURE 54
:
AC VOLTAGE WAVEFORM @ THE SOURCE AFTER LR
FILTER IS IMPLEMENTED
74
FIGURE 55
:
AC CURRENT WAVEFORM @ THE SOURCE IS BEING
CLEANED UP AFTER LR FILTER IS IMPLEMENTED
74
FIGURE 56
:
FFT OF THE AC CURRENT WAVEFORM @ THE SOURCE
74
v
LIST OF TABLES
PAGE
TABLE 1 :
CLASSIFICATION AND VOLTAGE DISTORTION LIMITS
FOR INDIVIDUAL USERS (LOW-VOLTAGE SYSTEMS)
6
TABLE 2 :
MAXIMUM HARMONIC CURRENT DISTORTION IN PERCENT
OF L
7
TABLE 3 :
ADVANTAGES & DISADVANTAGES FOR LC FILTER
24
TABLE 4 :
ADVANTAGES & DISADVANTAGES FOR RC FILTER
24
TABLE 5 :
ADVANTAGES & DISADVANTAGES FOR RL FILTER
25
TABLE 6 :
PRICE OF RESISTORS
25
TABLE 7 :
PRICE OF CAPACITORS
26
TABLE 8 :
PRICE OF INDUCTORS
27
I
vi
LIST OF SYMBOLS
Page
SYMBOL 1
:
AC SOURCE
12
SYMBOL 2
:
INDUCTOR
12
SYMBOL 3
:
CAPACITOR
13
SYMBOL 4
:
LINE FILTER
14
SYMBOL 5
:
STEP-DOWN TRANSFORMER
15
SYMBOL 6
:
DIODE
16
SYMBOL 7
:
FULL-WAVE BRIDGE RECTIFIER
17
SYMBOL 8
:
GROUND
17
vii
INTRODUCTION
1.1
PROJECT BACKGROUND
Nowadays in the industries, power supplies are commonly used as a source of
an electrical power. It is a device that provides the power to the output load which is
being defined as the power supply unit (PSU). As a standard in the industry, switchmode topology is being implemented in the power supplies, also known as the
switching-mode power supply, SMPS or just simply called the switcher as another
term.
Due to the chopping of DC link voltage in the typical Switch-Mode Power
Supplies (SMPS), it induces pulsating input current and distorted input voltage.
Example: Based on the investigation result, the building wiring losses is related to the
powering nonlinear electronic load equipment, as it exceeds 2 times the losses for the
normal linear loads. As a nonlinear/linear electronic load, an assembly that generates
a loading effect on the electronic circuit. It can also be used as a replacement for a
conventional load resistor.
In order to eliminate harmonics, passive filters are the normal approach as in
the recent research; active filters are being used and turn out to have promising results
in these applications. A passive filter which is an electric filter that comprises of
passive components, like resistors, inductors or capacitors. It won’t have any active
elements like vacuum tubes or transistors in it. For active filter, a filter which involves
an amplifier with a set of conventional passive filters elements that produce a desired
fixed/tuneable pass/rejection characteristic.
Things to take note eventually, the cost and complexity could be the
prohibiting factor. As the complexity, it would be depends on the design of the
circuitry, as how complicated or simplified can the circuit be. And for the cost, it is
determined by the parts used where the best result is obtained.
1
Therefore, the scope of the project involves a better understanding of the
techniques, not only on the harmonic generation/elimination point of view, and also
on the cost factor and benefits in implementing such topologies.
1.2
PROJECT OBJECTIVE
The goal is to build a simulation model of the Converter using the PSIM
circuit simulator. This project will be based on the designing of the circuit with the
help of the software. The final aim is to achieve the minimum voltage/current
distortion on the inputs with filters implementation, costs and benefits to be
considered as well. Standards of IEEE can not be missed out, as it is a regulation to be
followed as for the product to be used in the industry areas safely.
1.3
OVERALL PROJECT OBJECTIVE
The project aim is to build a simulation model that involves a multiple
circuitries compiled together which followed by an AC source, a line filter, step-down
transformer, a full-wave bridge rectifier, a filter capacitor and a DC-DC converter.
This project also allows the author to have a better understanding on the
implementation of filters like RC, RL or LR in order to achieve minimum distortion
on the input current at the AC source, and also require meeting the standards of IEEE.
In addition, it also allows the author to get to know more about different types of
converters available in the market and its functionality. That’s the main operation of
the project.
1.4
PROPOSED APPROACH
Figure 1 shows the block diagram of a complex Switch-Mode Power Supplies.
This circuit is a very complex one, compared to a typical one which just comprises an
AC input, a line filter, a transformer, a bridge rectifier, a filter capacitor and a
converter. This circuit requires these components to construct a basic power supply in
order to achieve a DC output.
2
Figure1: Block Diagram of a Complex SMPS
The circuit will flows in a manner that an AC input through a line filter, as to
minimise the harmonics on the input current, then through a transformer, as to step
down the AC signal as per required, then through a bridge of rectifier as to achieve a
DC signal, then through a filter capacitor to achieve a clean DC signal then through
the converter to get the desired DC output for other applications.
1.5
SKILLS REVIEW
This project requires the knowledge on both hardware and software
engineering and the understanding of basic mathematics theory. Besides, other skills
like information gathering and research, time management and project management
are also very important throughout the completion of this project.
First of all, time and project management skills are the two most important
skills which are required. This is because of the tight schedule to cope with my full
time job that requires OT very often. Most of the time is spent on the research of
information needed, especially in the initial stage of the project overview to have a
3
better understanding on how to design the circuit and also how to use the software to
do my simulation.
This is a new challenge to me as I have no experience in using such software
before during my poly life, as it will be tough at the beginning as it takes time to
explore the software. Nevertheless this Project work is being execute according to the
project schedule so that it can be completed and meet the objective of the project.
4
LITERATURE REVIEW
2.1
IEEE STANDARD (STD-519)
IEEE Standards Association (IEEE-SA) is a leading developer of industry
standards in a board-range of industries. Globally recognized, as the IEEE-SA has
strategic relationships with the IEC (International Electrotechnical Commission), ISO
(International Organization for Standardization), and the ITU (International
Telecommunication Union) that satisfies all SDO (Service Data Objects)
requirements set by the World Trade Organization, offering more paths to
international standardization.
For the original IEEE Std 519 specification in 1981, it focus more on the
matter of system voltage distortion, which depends on the system characteristics. In
order to determine voltage distortion, potential equipment suppliers had to perform
detailed system studies often. Therefore, unwanted effects could always be remedied
by system as well as equipment changes.
For the revised IEEE std 519 specification in 1992, it documents the harmonic
currents drawn by the users’ equipment that is defined. This is something that the
manufacturers can address in equipment design, which can provide additional help for
the designers and the users. There is also a system factor related due to the tolerable
harmonic currents to be defined to the system load. Overall, the system definition can
be less detailed and the performance expectations will be more readily determined.
2.1.1
VOLTAGE DISTORTION
Voltage distortion defines the relationship between the total harmonic
voltage and the total fundamental voltage. Thus, if the fundamental AC line to
neutral voltage is V L N and the total line to neutral harmonic voltage is V H ,
then
Total Harmonic Voltage Distortion =
V
V
H
L N
5
where
V
H
=
 V
h  25
2
h2
h
An upper summation limit of h = 25 is chosen for calculation purposes.
It gives a good practical summary result. Recommended voltage distortion
limits are being summarized in Table 1.
 Multiply this value by V/480 for other than 480V
systems
+ Special applications include hospitals and airports
Table 1: Classification and Voltage Distortion Limits for Individual Users
(Low-Voltage Systems)
http://media.wiley.com/product_data/excerpt/43/07803539/0780353943.pdf
2.1.2
CURRENT DISTORTION
Current distortion defines the relationship between the total harmonic
current and the fundamental current in much of the same way as voltage
distortion. However, there are some application differences which need to be
recognized. These will include:

Current harmonic limits depend upon the system short-circuit current
capability at the point of interest.

Current harmonic percentages apply to individual harmonic currents. They
are expected relative to the total system fundamental load current for the
worst case normal operating conditions lasting more than one hour. As the
worst case operating conditions will be expressed relative to the average
current of maximum demand, preferably for the preceding 12 months.
6

Total demand distortion TDD is the total harmonic current distortion given
by
TDD =
I
I
H
L
where IL is the maximum demand load current (fundamental frequency
component) at the PCC derived from a 15-minute or 30-minute billing
demand kVA. And IH is given by
I
H
=

h  25
h2
I
2
h
The upper summation limit of h = 25 is chosen for calculation purposes,
that gives a good practical result.
The system harmonic current limits recommended in IEEE Std 519
1992 are being shown in Table 2 for 6-pulse systems. For higher-pulse
numbers, larger characteristic harmonics are allowed in the ratio (pulse
number/6), provided that non-characteristic harmonics are less than 25% of
the limits specified in the table.
TABLE 2: Maximum Harmonic Current Distortion in Percent of
I
L
7
http://media.wiley.com/product_data/excerpt/43/07803539/0780353943.pdf
IEEE STD-519 defines the limits for various harmonic indices that correlate to
harmonic effects. The defined indices are:
-
Depth of notches, total notch area, and distortion of the bus voltage by
commutation notches
-
Individual and total voltage distortion
-
Individual and total current distortion
Misuse of IEEE STD-519:
-
Common misuse is the application of the tables to other than utility-customer
interface
-
Often cited as an equipment specification
-
Often used as a selling point
-
The tables were designed to demonstrate the relationship between voltage and
current through standard utility transformers
-
Any other transformer or physical arrangement makes the tables inappropriate
-
Applying the table values at other than the PCC is inappropriate
Proper Use of Standard 519
-
Need to identify 3 parameters
(1) PCC – point where other use is made of the voltage
(2)
I
SC
– Available short circuit current at the PCC
(3) II – Maximum demand load current at the PCC
-
Those may be easy, maybe not
-
Those 3 parameters govern the use of Standard 519
-
Strictly application parameters
8
2.2
POWER SUPPLY
Power supply is also a reference to the electrical power source. Electric power
is being defined in a term where electrical energy is transferred by an electric circuit.
It is also a device or a system that provides the power to the output load, which is
being called as the power supply unit or PSU. This term is commonly used in the
engineering industry.
2.2.1
LINEAR MODE POWER SUPPLY
Figure 2: Example of a Linear Power Supply
http://en.wikipedia.org/wiki/Power_supply#Linear_power_supply
A linear power supply is normally link up with a transformer to reduce the
voltage from the mains to a much lower voltage which depends on the inductance of
the transformer. A rectifier is used in the loop to produce DC voltage, and a capacitor
is used to smooth out the pulsating current from the rectifier. However, there will be
always small deviations that remain on the signal, which is known as ripple. These
normally occur at the frequency that is related to the AC power frequency. Example
50Hz for Asia and 60Hz for Europe.
As the voltage being produced out by the unregulated power supply, it will
varies depend on the load and also the variations in the AC supply voltage. For
9
applications that are critical and sensitive, a linear regulator will be used to stabilize
and adjust the voltage; this will helps to minimize the ripple and noise in the output.
And also it provides functions like current limiting that protect the power supply from
being over-current, and acts as a safety precautions.
For the simplest DC power supply that can be find in the market is the
rechargeable flashlights, where it is only made up of a single diode and resistor which
is connected in series with the AC supply.
2.2.2
SWITCH MODE POWER SUPPLY
Figure 3: Example of a Switch-Mode Power Supply
http://en.wikipedia.org/wiki/Power_supply#Switched-mode_power_supply
A switch-mode power supply is known as an electronic power supply unit
(PSU) that induces a switching regulator in it, so as to get the required output voltage.
A switch-mode power supply or another term, SMPS, is also regards as a power
converter that generates power from the source to the load with no loss in an ideal
situation. In another way, it is to output a reliable voltage in different aspects
compared to the input voltage.
It can operates in a different principle, as when the AC input is being rectified
without getting involved with a transformer, to get a DC output. This is being divided
into small pieces by electronic switch, and as the output requirements getting bigger,
10
the size will be increased.
It usually runs at high speed in the range of 10kHz to 1MHz, and occurs when
the high frequency and high voltage are being step down by the transformers, and
going through a smoothing capacitors to achieve a clean signal than the linear power
supply. Then AC is being rectified to DC again, after the secondary side of the
transformer. The power supply requires a feedback controller so as to monitor current
and also to maintain a stable output.
In the modern world now, safety precautions are being implemented in the
switch-mode power supplies. The crowbar circuit is designed in a way to protect the
device and the user from any damage. Example: If any abnormal symptoms in terms
of voltage or current, the power supply will automatically shut itself off as it assumed
a short circuit before any damage happened. As PC power supplies is one of the
device that have this capability and provide good power signal for decades.
2.3
CIRCUIT DESIGN AND SOFTWARE OVERVIEW
For this project, the simulation model is built up of two main sections, the
hardware overview and the software overview. For hardware overview, it will be
focusing more on the designing portion and hardware implementation. As for the
software overview, it will be the Ltspice that is being chosen over PSIM to collect
results from the simulation model. So below sections will be discussed more on the
individual section.
2.3.1 CIRCUIT DESIGN OVERVIEW
This project requires a better understanding in circuit analysis while designing
the simulation model. A strong fundamental knowledge on hardware is necessary in
order to be implementing during the designing process. Things like different
components used, different types of filters and different types of converters are
11
needed as part of the simulation model. It is also the project requirement, as further
details will be elaborated below as follows.
2.3.1.1
DESCRIPTION OF DIFFERENT COMPONENTS USED
Symbol 1: AC Source
http://en.wikipedia.org/wiki/Voltage_source
In the typical circuit drawing, the theory of an ideal voltage
source is a circuit element where the voltage across, is independent with the
current through it, as it is only applies in the mathematical models of circuits.
An independent voltage source is being defined when the voltage across the
ideal voltage source is being specified independently by any other variable in a
circuit. In another term, called as the dependent or controlled voltage source, It
is being defined when the voltage across an ideal voltage source is affected by
some other voltage or current in a circuit. Symbol 1 show the picture of an AC
source commonly used to denote voltage sources in circuit schematics.
Symbol 2: Inductor
http://www.glentek.com/glentek/inddesc.aspx
12
Inductors are commonly used for the these reasons:
1)
During the operation of a PWM (Pulse-Width-Modulated) servo
amplifier with a low inductance (i.e. less than 300 micro Henries) servo
motor, an inductor is required to be connected in series with the motor to
help to stabilize the current waveform from the servo amplifier.
2) During the operation of a PWM (Pulse-Width-Modulated) servo
amplifier with a servo motor, an inductor is required to be connected in
series with the motor that will help to smooth out the edges of the current
waveform from the amplifier, as to reduce the conducted and radiated
noise of the servo system.
Symbol 3: Capacitor
http://library.thinkquest.org/C006657/electronics/capacitor.htm
The capacitor is a device for storing an electrical charge. In its
simplest form a capacitor made up of two metal plates separated by a nonconducting layer called the dielectric.
The electrical size of a capacitor is its capacitance value and
also determined the amount of electric charge that it can hold.
Capacitors are used in a way that is it limited in the amount of
electric charge that they can absorb. They are also used to conduct direct
current and function well as conductors in alternating-current circuits. This
important characteristic makes them useful when direct current must be
prevented from entering some part of an electric circuit.
13
Symbol 4: Line Filter
http://www.powerdesignindia.co.in/ART_8800563065_2900003_TA_69f4082
9.HTM
http://www.siemens-profibus.com/line-filter-schematic/
It is a device that used to transmit electricity or light. The
selection for transmission is being determined on the basis of the frequency or
the phase.
Electrical filters are often one of the following types.

Low-pass filter – Low frequencies are passed, high frequencies are
attenuated.

High-pass filter – High frequencies are passed, low frequencies are
attenuated.

Band-pass filter – Only frequencies within a frequency band are passed.

Band-stop filter – Only frequencies within a frequency band are
attenuated.

All-pass filter – All frequencies are passed, but the phase of the output is
modified.
14
Symbol 5: Step-Down Transformer
http://www.google.com.sg/imglanding?q=diagram%20of%20step%20down%
20transformer&imgurl=http://scienceaid.co.uk/physics/electricity/images/transfo
rmer.png&imgrefurl=http://scienceaid.co.uk/physics/electricity/electromagnetis
m.html&h=321&w=400&sz=22&tbnid=ostVjboR9vW6oM:&tbnh=100&tbnw=1
24&prev=/images%3Fq%3Ddiagram%2Bof%2Bstep%2Bdown%2Btransforme
r&hl=en&usg=__qYEDU115TWhf9JncWL7futR7tBU=&ei=vPWeS4XTFYHCr
AeJyb2gDg&sa=X&oi=image_result&resnum=2&ct=image&ved=0CBEQ9Qew
AQ&start=0#tbnid=ucLhWdYo6r1lDM&start=9
http://en.wikipedia.org/wiki/Transformer
A transformer is a device that transfers the electrical energy
from one to another through the inductive conductors—the transformer’s coils.
The varying current in the primary winding is to create the varying magnetic
flux in the transformer’s core, so to have a varying magnetic field through the
secondary winding. This varying magnetic field is to induce a varying
electromotive force (EMF) in the secondary winding. This effect is called the
mutual induction.
In an ideal transformer, the induced voltage in the secondary
winding (VS) which is in proportion to the primary voltage (VP), is given by
the ratio of the number of turns in the secondary (NS) to the number of turns in
the primary (NP) as follows:
15
In order to make a correct selection of the ratio of turns, a
transformer that allows the alternating current voltage to be “stepped up” by
making NS greater than NP, or “stepped down” by making NS less than NP.
Symbol 6: Diode
http://www.ehow.com/facts_5615997_diode-theory.html
Diodes are semiconductors components that work in one-way
valves. An ideal diode which is called forward-biased, allows the current to
flow in one direction. But in another way, a diode with the current flow in the
wrong direction is called reverse-biased.
The symbol for a diode looks like an arrow; it is to indicate the
current is blocked when going in the opposite direction, as the arrow has a bar
at the pointed end.
Many diodes are being manufactured by silicon or germanium.
Diodes operate in a way that it will conduct when the forward voltage reaches
a value, typically 0.6 volts for silicon.
Small signal diodes are very common used in the market,
typically in the applications of performing as switches, regulating current or
converting AC to DC. Other common types include LEDS, photodiodes and
power rectifiers.
16
And also diodes are made to conduct when they are in reversebiased conditions. These include zeners that used to regulate voltage, and
varactors that behave like variable capacitors.
Diodes are usually found in many devices, such as surge
protectors, lasers, light sources and sensors. They are also used to create
power supplies and voltage doublers in certain ways.
Symbol 7: Full Wave Bridge Rectifier
http://en.wikipedia.org/wiki/Rectifier
A full-wave rectifier is used to convert the whole of the input
waveform to one of constant polarity (positive or negative) at its output. Fullwave rectification is a process that converts both polarities of the input
waveform to DC (direct current), and turn out to be more efficient. However,
in a circuit with a non-center tapped transformer, four diodes are required
instead of the one needed for half-wave rectification. Four diodes are arranged
in this way, therefore they are called a diode bridge or bridge rectifier:
Symbol 8: Ground
http://www.ask.com/wiki/Ground_%28electricity%29
17
In the terms of electric engineering, ground or earth can be the
reference point in the circuit as where other voltages are being measured, or a
common return path for electric current, or a direct physical connection to the
Earth.
Electrical circuits need to be connected to ground for several
reasons in any applications.
2. In the mains powered equipment, any exposed metal parts must be
connected to ground, so to prevent contact with a dangerous voltage if the
electrical insulation fails.
3. The purpose of connecting to ground is to limit the build-up of static
electricity when handling any flammable products or when repairing any
electronic devices.
4. In some telegraph and power transmission circuits, the ground itself can be
used as one conductor of the circuit, as to save the cost of installing a
separate return conductor.
The use of the term ground (or earth) is so common in the
engineering field, as in electrical and electronics applications like circuits in
vehicles such as ships, aircraft, and spacecraft can have the “ground”
connection without any actual connection to the Earth.
2.3.1.2
DIFFERENT TYPES OF FILTERS
In this section, passive filters will be the main focus as
compared to active filters, as it would be more applicable in this
project. More information will be elaborated below on why passive filter is
chosen.
A passive filter is an electronic filter that comprises of passive
elements which compare to an active filter. An external source is not required
due to most of the filters are linear, therefore passive filters only involved with
18
these four basic linear components in most of the situations. They are the
resistors, capacitors, inductors and transformers. Transmission lines are
involved only for complex filters where requires nonlinear elements.
Figure 4: Example of a Passive Filter application
http://en.wikipedia.org/wiki/Passivity_%28engineering%29
Passive filter has these advantages over the active filter:

Guaranteed stability

Passive filters can scale better to large signals, where active devices are
often impractical

No power consumption, but the desired signal is invariably attenuated. If
no resistors are used, the amount of signal loss is directly related to the
quality of the components used.

Inexpensive

For linear filters, generally, more linear than filters including active
elements
Comparison between passive filter and active filter: A passive
filter does not have any active components like transistors or op-amps. For
example, a basic low-pass passive filter is made up of a resistor and a
capacitor, and the output signal can never have more power than the input
19
signal due to no gain present in its elements. Whereas an active filter involves
more than one transistors or amplifiers, as the output signal can be larger than
the input signal after filtering.
These are the three that belong to the Passive Filters: (1) The
R-L Circuit, (2) The L-C Circuit and (3) The R-C Circuit.
(1)
R-L Circuit
Figure 5: R-L Filter Design
http://en.wikipedia.org/wiki/RL_circuit
It is a resistor-inductor circuit which is called as the RL filter or
RL network. It is one of the simplest analogue infinite impulse response
electronic filters. Analogue filters are a basic building block of signal
processing that commonly used in electronics, and the infinite impulse
response (IIR) is the property of signal processing systems. This filter
comprises of a resistor and an inductor, input by a voltage source and
connected up either in series or parallel connection.
To determine the time constant of R-L circuit, used this
formula to make the calculation to find either one of the values.
T= L
R
20
(2)
L-C Circuit
Figure 6: L-C Filter Design
http://en.wikipedia.org/wiki/LC_circuit
It is a LC circuit, as it is a resonant/tuned circuit that comprises
of an inductor and a capacitor. It is connected up together, where the electric
current moves between them at its resonant frequency. Its job is to generate
signals or picking out a signal from the complex signal at a particular
frequency. Oscillators, filters, tuners and mixers are normally the key
components. Although it is classified as an ideal model, it is because
there is no dissipation energy involved due to the resistance, where is a
measure of its opposition of the current’s passage.
To determine the time constant of L-C circuit, used this
formula to make the calculation to find either one of the values.
T=
1/ 2
( LC )
21
(3)
R-C Circuit
Figure 7: R-C Filter Design
http://en.wikipedia.org/wiki/RC_circuit
It is a resistor-capacitor circuit, which is called as the RC filter
or network. It is made up of resistors and capacitors in an electric circuit and is
driven by a voltage/current source. Its job is to ‘filter’ a signal waveform on
the output signals, where there are a few versions of filters, like the high-pass
filter, low-pass filter and band-pass filter. The commonly used to minimize the
distortion on the signal is using a low pass version.
Simple description on the filters:
(1) High-pass – It passes high frequencies, but attenuates frequencies lower
than the cutoff frequency.
(2) Low-pass – It passes low frequency signals but attenuates signals with
frequencies higher than the cutoff frequency.
(3) Band-pass – It passes frequencies within a certain range and rejects
frequencies outside the range.
To determine the time constant of R-C circuit, used this
formula to make the calculation to find either one of the values.
T = RC
22
(4)
Reactance Calculation
Resistance is a value or an indication to represent the opposition towards
current flow in a DC circuit, as being able to calculate using Ohm’s Law.
Voltage = Resistance x Current. After a power transition in the DC circuit,
inductors are used that act as a very low ohm resistor whereas capacitors are
used that act as open circuits.
Compared to AC circuits, the opposition to current flow is being
measured in terms of impedance, which is a combination of resistance and
reactance. For resistor, resistance is the same as impedance. For inductors and
capacitors, their impedance are normally greater than the reactance, as its
reactance varies depends on the frequency.
These are the formulas to take note for the calculation.
Formulas that calculate capacitance and inductance from reactance:
1.
Inductance = [ Reactance / 2 X PI X Frequency ] Henry
2.
Capacitance = [ 1 / 2 X PI X Frequency X Reactance ] Farad
Formulas that calculate inductance and capacitance reactance:
1.
Inductance = 2 X PI X Frequency X Inductance
2.
Capacitance = 1 / 2 X PI X Frequency X Capacitance
Important things to take note:
1.
Frequency increases will affect the inductive reactance to increase and
capacitive reactance to decrease.
2.
Impedance (Z) in the AC circuit is the combination of resistance and
reactance. Same rules apply in calculating series or parallel resistances
in AC and DC circuit.
3.
Resonance is regards as a frequency where the reactance of a capacitor
and an inductor in a circuit that measures the same.
23
4.
If X > 0, the reactance is said to be inductive.
5.
If X < 0, the reactance is said to be capacitive.
6.
Inductive reactance
X
L
is proportional to the frequency and the
X
C
is inversely proportional to the frequency
inductance.
7.
Capacitive reactance
and the capacitance.
(5)
Comparison of Filters
LC Filter:
Advantages
Disadvantages
1. Filter order of LC is twice of RC 1. Must be designed for specified source
and load resistances
2. LC is lossless in terms of heat
2. Inductors that are close to ideal inductors
are difficult to design, so the final design
must be “tweaked” to allow the finite Q,
distributed capacitance
3 Inductors for low frequency applications
are physically large
Table 3: Advantages & Disadvantages for LC Filter
RC Filter:
Advantages
Disadvantages
1. Filter characteristics do not depend on 1. It consume more power as heating loss
load capacitance
2. Capacitors are physically smaller than 2. The gain-bandwidth product must be
inductors at low frequencies
higher than the maximum frequency of
interest. This limits their application to
relatively low frequencies.
Table 4: Advantages & Disadvantages for RC Filter
24
RL Filter:
Advantages
Disadvantages
1. One of the simplest analogue infinite 1. Resistors have no frequency –selective
impulse response electronic filters
properties, added to inductor/capacitor
to determine the time-constant of the
circuit
Table 5: Advantages & Disadvantages for RL Filter
(6)
Costs of Components
Resistors:
Value (ohm) Wattage (W) Price (US) Tolerance (%)
10 – 820K
1/2W
0.45
5%
1M – 8.2M
1/2W
0.49
5%
10M – 22M
1/2W
0.55
5%
1 – 20M
1W
0.59
5%
30M – 50M
1W
1.59
5%
1 – 8.2
2W
0.79
5%
10 – 1M
2W
0.85
5%
1.2M – 10M
2W
1.25
5%
12M – 22M
2W
1.59
5%
5 – 75
5W
0.36
5%
100 – 25K
5W
0.37
5%
0.5 – 25K
10W
0.49
5%
30K – 50K
10W
0.79
5%
Table 6 : Price of Resistors
http://www.justradios.com/resorderform.html
25
Capacitors:
Value (uF) / Voltage (V) Price (US) Value (uF) / Voltage (V) Price (US)
10uF / 25V
0.40
10uF / 160V
0.75
10uF / 50V
0.40
22uF / 160V
0.60
100uF / 50V
0.75
100uF / 250V
2.50
22uF / 50V
0.45
0.02uF / 250V
0.35
220uF / 50V
1.20
0.22uF / 250V
0.60
4.7uF / 50V
0.40
2.2uF / 250V
0.90
470uF / 50V
1.65
0.047uF / 250V
0.40
1uF / 100V
0.50
0.22uF / 400V
0.90
10uF / 100V
0.70
2.2uF / 400V
0.90
0.47uF / 100V
0.55
0.047uF / 400V
0.45
4.7uF / 100V
0.75
0.47uF / 400V
1.10
47uF / 100V
0.80
0.001uF / 600V
0.40
150uF / 100V
0.75
0.1uF / 600V
0.65
0.01uF / 200V
0.35
0.002uF / 600V
0.40
0.1uF / 200V
0.45
0.022uF / 600V
0.50
1uF / 200V
0.65
0.003uF / 600V
0.35
0.03uF / 200V
0.35
0.03uF / 600V
0.45
10uF / 450V
1.50
0.0047uF / 600V
0.40
100uF / 450V
4.75
1uF / 1000V
0.70
22uF / 450V
3.25
0.022uF / 1000V
0.80
0.001uF / 1600V
0.70
0.001uF / 2000V
0.30
0.01uF / 1600V
1.00
1000uF / 50V
2.25
Table 7: Price of Capacitors
http://www.verntisdale.com/caplist.htm
26
Inductors:
14 AWG
12 AWG
10 AWG
8 AWG
Value (mH) Price (US) Price (US) Price (US) Price (US)
0.15
11.40
18.67
30.26
52.00
0.20
12.26
19.92
32.46
55.64
0.25
14.56
23.65
38.50
66.27
0.30
16.66
27.39
44.62
76.20
0.35
18.29
30.07
48.65
83.50
0.40
18.96
30.93
50.47
86.57
0.50
20.68
33.80
54.97
94.52
0.60
21.64
35.34
57.36
98.73
0.70
24.13
39.45
64.16
110.32
0.80
25.66
41.85
68.18
117.11
0.90
27.20
44.34
72.11
123.91
1.00
27.77
45.29
73.54
126.59
100mH
3.80
-
-
-
Table 8: Price of Inductors
http://www.northcreekmusic.com/NorthCreekCoilPrices.PDF
http://sg.farnell.com/toko/10rb104k/inductor-100mh/dp/1193630
2.3.1.3
DIFFERENT TYPES OF CONVERTERS
In this section, it covers about the theory and operation of
different types of converters that are available in the market. And also
commonly used in the switch-mode power supplies.
It is being differentiate into two categories: (1) Non-isolated
converters which are the Buck converter and Boost converter. (2) Isolated
converters which are the Flyback converter and Forward converter.
27
Non-isolated: Buck Converter
Figure 8: Buck Converter Circuit
http://www.nxp.com/acrobat_download/applicationnotes/APPCHP2.pdf
A buck converter which is also known as a step-down DC-DC
converter, as in the electronic engineering industry, a DC-DC converter is an
electronic circuit that converts the source from one voltage to the other. It is
defined a class of the power converter. In similarity, the design is close to the
boost converter, as in the switch-mode power supply, it comprises two
switches (a transistor and a diode) and an inductor and a capacitor.
Its operation is pretty straightforward, when the switch TR1 is
kick on, the input voltage is being applied to the inductor L1 before to the
output. There is a formula for the inductor current to be build up according to
the Faraday’s law as shown below:
V=L
dI
dt
In another way, when the switch is turned off, the voltage that is present across
the inductor reverses and the diode D1 becomes forward biased. This is to
allow the energy to be stored in the inductor and delivered to the output, and
the continuous current will be smoothening by the capacitor Co. Below is the
desired outputs of the Buck Converter circuit.
28
Figure 9: Desired Outputs of Buck Converter Circuit
http://www.nxp.com/acrobat_download/applicationnotes/APPCHP2.pdf
The LC filter in the circuit has the effect on the applied pulsating input that
produces a smooth dc output voltage and current. Therefore, it has minimal
ripple components superimposed.
Non-isolated: Boost Converter
Figure 10: Boost Converter Circuit
http://www.nxp.com/acrobat_download/applicationnotes/APPCHP2.pdf
A boost converter which is also called a step-up converter is a
power converter that has the output DC voltage which is higher than the input
DC voltage. It is also defined as a class of switching-mode power supply
(SMPS) that comprises at least two switches (a diode and a transistor) and not
29
missing out at least one energy storage element. Filters are commonly used as
to minimize the output voltage ripple, and usually consist of capacitors with
the combination of inductors.
Its operation is more complex than the buck, as when the
switch is kick on, the diode D1 is reverse biased, and the
V
in
that applied
across the inductor L1. The current is being built up in the inductor to a peak
value, either from zero current in a discontinuous mode, or an initial value in
the continuous mode. In another way, when the switch is turned off, the
voltage across L1 is reverses, and causing the voltage at the diode to rise
above the input voltage. The diode then conducts the energy stored in the
inductor, plus energy direct from the supply to the smoothing capacitor and
load. And also
V
o
is always bigger than
V
in
, making it as a step-up
converter. As for continuous mode operation, the boost dc equation is given as
below:
Vo
1
=
Vi
1 D
As the output can only depends upon the input and duty cycle, therefore in
order to control the duty cycle, the output regulation is achieved.
Figure 11: Desired Outputs of Boost Converter Circuit
http://www.nxp.com/acrobat_download/applicationnotes/APPCHP2.pdf
30
If the boost is used in discontinuous mode, the peak transistor and the diode
currents will be higher, and the output capacitor will need to be doubled in
size to achieve the same amount of ripple output as compared in continuous
mode. Therefore, the output will be dependent on the load and results in
poorer load regulation.
Isolated: Flyback Converter
Figure 12: Flyback Converter Circuit
http://www.nxp.com/acrobat_download/applicationnotes/APPCHP2.pdf
A Flyback converter is also known as a buck-boost converter. It
can be used in both AC/DC and DC/DC conversion with a galvanic isolation.
Its usage is to isolate functional sections of the electric portions so that to
prevent charging elements moving from one place to another. It is where the
inductor split to form the transformer, as the voltage ratios are multiplied with
an advantage in isolation.
Its operation turns out to be the simplest of a single-ended
flyback converter, where the use of a single transistor switch means that it’s
31
only in unipolar condition so that the transformer can be driven. This results in
a large core size. When the transistor is turned on, current builds up in the
primary and energy is stored in the core, it is then released to the output
through the secondary when the switch is turned off.
Figure 13: Desired Outputs of Flyback Converter Circuit
http://www.nxp.com/acrobat_download/applicationnotes/APPCHP2.pdf
The windings polarity works in a way that the output diode
blocks the on-time of the transistor, as when the transistor turns off, the
secondary voltage reverses, as to maintain a constant flux in the core and force
the secondary current to flow through the diode and then to the output.
The fact is that all the output power of the flyback is stored in
2
the core as 1 / 2 LI energy, which means that that core size and cost will be
much greater than the other topologies. Due to the addition of the poor
unipolar core utilisation, that cause the transformer bulk to be the one of the
major drawbacks of the converter.
Flyback formula Calculation:
Converter efficiency, η = 80%; Max duty cycle,
Max transistor voltage, V ce or V ds =
2V
in (max)
D
max
= 0.45
+ leakage spike
32
Max transistor current,
I
dc voltage gain:- (a) continuous
C
;
I
D
=2[
P
out
/η
D
max
V
min
]
Vo
D
=n
1 D
Vin
(b) Discontinuous
Vo
=D
Vin
R
2
L
T
L
P
Applications:- Lowest cost, multiple output supplies in the 20 to 200W range.
E.g. mains input T.V. supplies, small computer supplies, E.H.T.
Supplies.
Isolated: Forward Converter
Figure 14: Forward Converter Circuit
http://www.nxp.com/acrobat_download/applicationnotes/APPCHP2.pdf
It is just another switch-mode power supply circuit. It is used to
produce controlled dc voltage which is isolated from an unregulated dc input
supply. In terms of performance with respect with the fly-back circuit, it is
more energy efficient, and is used in applications where requires higher power
output. Therefore in the topology theory, the output filtering circuit is not as
simple as the fly-back converter.
33
Its operation is also something like a single switch isolated
topology, similar to buck converter with addition of a transformer and a diode
at the output. In compare with flyback, it has the true transformer action,
where energy is transferred directly to the output through the inductor during
the on-time of the transistor as the polarity of the secondary winding is
directly opposite as compared to the flyback, therefore it allows the current to
flow through the blocking diode D1. During the on-time period, the current
flows causes the energy to be built up at the output inductor L1, but when it is
off, it reverses, as the diode goes from conducting to blocking mode and affect
D2 to be forward biased and create a path for the inductor to continue flow.
And also it allows the energy stored in L1 to be released to the load.
Figure 15: Desired Outputs of Forward Converter Circuit
http://www.nxp.com/acrobat_download/applicationnotes/APPCHP2.pdf
In continuous mode where forward converter always in, that
has very low peak input and output currents with small ripple components. In
discontinuous mode, it will greatly affect the values and also the amount of
harmonic being generated. This prove that the existence of the control
problems in flyback in continuous mode but no advantages to be mentioned in
discontinuous mode.
34
Forward formula calculation:
Converter efficiency, η = 80%; Max duty cycle,
Max transistor voltage, V ce or V ds =
Max transistor current,
Dc voltage gain:-
V
V
O
I
C
;
I
D
=
P
2V
out
D
max
= 0.45
in (max)
/η
D
max
V
min
=n D
in
Applications:- Low cost, low output ripple, multiple output supplies in the 50
to 400W range. E.g. small computer supplies, DC/DC
converters.
2.3.2 SOFTWARE OVERVIEW
This project requires simulation software to run the simulation model that is
being designed as part of the project requirement. Therefore, PSIM is the chosen one
that being assigned for the project, but due to limitations of the software, it is being
replaced by LTspice. Further details will be elaborated below as follows.
2.3.2.1
PSIM
PSIM stands for Physical Security Information Management.
Its software systems are being designed to analyze information from any
devices and systems, which can automatically or manually resolve problems in
real time.
These are the tools required for complete PSIM software
system for the situation management:

Data collection

Verification

Analysis

Resolution

Tracking
35
PSIM is also simulation software or a package which is
specially designed for power electronics and motor control applications. With
the benefits of fast simulation, friendly user interface and waveform
processing, it allows the simulation environment for power converter analysis,
control loop design, and motor drive system studies.
For the package, it comprises of three programs: circuit
schematic editor SIM-CAD*, PSIM simulator and waveform processing
program SIMVIEW*. The simulation environment is being illustrated below
as follows:
Figure 16: Simulation Environment of PSIM
PSIM has its own problems in such applications. Below are the
operational limitations and deployment complexities of PSIM:

Requires integration with dozens of subsystem manufacturers because
of the market is fractured amongst many different providers.

Requires on-site integration services.

PSIM functionality is constrained by limitations of different subsystem
manufacturers can provide.

Suffers from exponential false alerts when attempting to cross-analyze
information from different subsystems.
That’s the reason why PSIM is being replaced by LTspice as
the simulation software for this project. More information on LTspice will be
elaborated after this.
36
2.3.2.2
LT SPICE
LTspice IV is known as a high performance Spice III simulator,
schematic capture and waveform viewer. With its enhancements and models
to ease the simulation of switching regulators, it made the switching to be fast
as compared to the normal one. This allows the user to monitor the waveforms
for most of the switching regulators in just a short period of time. This
comprises the download of Spice, Macro Models op amp models, which
include resistors and MOSFET models as well.
LTspice has its own benefits over PSIM, below are the reason
why using the SwitcherCAD III/LTspice.
- Stable SPICE circuit simulation with

Unlimited number of nodes

Schematic/symbol editor

Library of passive devices
- Fast simulation of switching mode power supplies (SMPS)
o Steady state detection
o Turn on transient
o Step response
o Efficiency / power computations
- Advanced analysis and simulation options
Therefore, LTspice has been chosen for this project due to its
benefits which comes over the problems of PSIM.
37
SIMULATION TESTING AND RESULTS
3.1
CIRCUIT DESIGN TESTING
During the process of designing the circuitries and testing, problems are being
encountered in regardless of the design portion or the testing portion. In order to make
the project works, and simulate efficiently, progressive stages are being implemented
so as to get the project worked out in the right path.

Stage 1
:
AC source connect up with a resistive load
A simple design is being executed for a start, with an AC
source of 230Vac, with its operating frequency of 50Hz, is
being connected up to a 50ohm resistive load.
Refer to Appendix B – Figure 18 for the schematic drawing.

Stage 2
:
AC source connect up with a step-down transformer then to a
resistive load
A step-down transformer is added on to the design for the next
stage, with AC source and load parameters remains. For the
step-down transformer, its primary inductance is 5H (Henry)
and its secondary inductance is 13mH (Henry) in order to stepdown from 20Vac to a 12Vac output at its secondary side of
transformer.
Refer to Appendix B – Figure 19 for the schematic drawing.

Stage 3
:
AC source connect up with a step-down transformer, then to a
full-wave bridge rectifier, then to a resistive load
38
Four diodes are added on to the design after the transformer, as
to construct a full-wave rectifier, so to convert from AC to DC.
Other parameters remains, and the diode used is 1N4148.
Refer to Appendix B – Figure 20 for the schematic drawing.

Stage 4
:
AC source connect up with a step-down transformer, then to a
full-wave rectifier, then to a filter capacitor, then to a resistive
load
A filter capacitor is added on to the design after the full-wave
rectifier, as to remove / clean off the harmonics on the DC
waveform. Other parameters remain.
Refer to Appendix B – Figure 21 for the schematic drawing.

Stage 5
:
AC source connect up with a step-down transformer, then to a
full-wave bridge rectifier, then to a filter capacitor, then to a
resistive-inductive load
The load is being changed into a resistive-inductive type, as in
the real–life of engineering, there is no such ideal case with a
resistive load. Resistive-inductive load is common everywhere,
and since it is not an ideal case, problems will arise; therefore
more things will need to be implemented onto the design to
resolve the issue.
Refer to Appendix B – Figure 22 for the schematic drawing.
39

Stage 6
:
AC source connect up with a step-down transformer, then to a
full-wave bridge rectifier, then to a filter capacitor, then to a
DC-DC converter, then to a resistive-inductive load
A DC-DC converter is added onto the design, as it is part of a
standard power supply circuits. Its purpose is to get the desired
dc voltage out for the applications. Over here, we will just
touch on Buck converter and Boost converter for some simple
theory knowledge.
Buck converter is a step-down converter where reduces its
input and output a lower voltage to its applications.
Boost converter is a step-up converter where increases its input
and output a higher voltage to its applications.
Refer to Appendix B – Figure 23 for the schematic diagram.

Stage 7
:
The final design of the simulation model with filter add-on
before the primary side of the transformer
A filter circuit / line filter is added onto the design to make up a
complete simple power supply. Its purpose is to minimize the
distortion on the current waveform to the minimal as to achieve
a clean current waveform back to the source.
There are also others filter circuitries, like the RC filter, LR
filter and the LC filter, where LC is the chosen one as the ideal
filter to be used for the project due to its characteristics. Also
other filters results will be show in the Appendix D &
Appendix E later on.
40
Refer to Appendix B – Figure 24 for the schematic diagram.
3.2
RESULTS
Below is the explanation and description of the individual stages of the design,
where some calculations will need to be done to prove the output results of the
individual circuitries.
Stage 1:
Based on the ohm’s law, the current flowing in the circuit is being determined
as:
V = IR
P = VI
230Vac = I x 50ohm
P = 230Vac X 4.6A
I = 230Vac / 50ohm
P = 1058W
I = 4.6A
* Proven
Refer to Appendix C – Figure 25 & 26 for the waveforms.
Note:
(1) When voltage value remained, as the resistance increased, the
current will decreased.
(2) When voltage value decreased, as the resistance remains, the
current will decreased.
(3) When voltage value increased, as the resistance remains, the
current will increased.
Stage 2:
Based on the formula, the secondary inductance is determined as:
Vs / Vp = Ns / Np
12 / 230 = Ns / 5
41
230Ns = 12 x 5
Ns = 60 / 230
Ns = 0.26H
But in the simulation, using 5H for the primary inductance, and 0.26H for the
secondary inductance, the output I get is 50Vac. As in order to achieve a 12V
output to be the input to the converter, the secondary side inductance is being
revised to be 13mH.
We have to alter / fine adjust the values, as real-life calculation does not
always meet the simulation requirements where it is being assumed as an ideal
model.
Based on the ohm’s law, the current flowing in the circuit is being determined
as:
V = IR
P = VI
12Vac = I x 50ohm
P = 12Vac X 0.24A
I = 12 / 50
P = 2.88W
I = 0.24A
* Proven
Refer to Appendix C – Figure 27 & 28 for the waveforms.
Note:
(1) When inductance increased, the voltage deceased.
(2) When inductance decreased, the voltage increased.
Stage 3:
There isn’t any formula need to be done for calculation, as its aim is to convert
AC signal to DC signal as a requirement in the theory of power supply. It will
not affect the output that much, and other parameters remain.
Refer to Appendix C – Figure 29 & 30 for the waveforms.
42
Stage 4:
There is a formula to be take note, but isn’t a need to be done for calculation,
as its aim is to minimize the ripple on the DC signal, a value of 950uF
capacitor is used as to achieve a clean 12V signal. In order to maintain a
steady 12V output, as the current is flowing @ about 0.24A.
Below is the formula on how to obtain the capacitance (Ch) as follows:
Ch = 2 X Po X Th / (V1² - V2²) X η
Ch
:
Capacity of the filtering capacitor
Po
:
Output power of module
Th
:
Hold-up time
V1
:
Input DC voltage = Input AC voltage (RMS) x √2
V2
:
Input DC voltage which can hold output voltage
η
:
Efficiency
Refer to Appendix C – Figure 31 & 32 for the waveforms.
Stage 5:
There isn’t any formula need to be done for calculation; the purpose is to
change the resistive load to resistive-inductive load as to match the reality in
the engineering field. Problems will arise when the model is not in an ideal
case, and distortion will appears on the current waveform. That’s the problem
that I will be facing for my project aim and find a solution to resolve it.
Reason why to solve the harmonics problem, is because:
1. Interference with electronic equipments
2. Overheating of supply transformers
3. Protect the source from being damaged
43
Some theory on the comparison between the inductive load and resistive load:
(1)
Inductive loads use magnetic loads. Examples – motors, solenoids, and
relays. If it moves it’s probably an inductive load.
(2)
Inductive loads can cause blowback voltage. Circuits should be
protected from this by diodes.
(3)
Blowback is caused by a surge of voltage created by the collapsing
magnetic field in an inductor.
(4)
Resistive loads convert current into other forms of energy, such as
heat. No risk of blowback.
Due to the load characteristic changed, the current is slightly being
affected by the load, as now the current is flowing @ about 0.22A.
Refer to Appendix C – Figure 33, 34, 35 & 36 for the waveforms.
Stage 6:
There isn’t a need for calculations even there are formulas available, as it
isn’t’ a requirement for the project, but it is good to take note of it. A converter
is added on as it is part of a power supply, to make up a complete power
supply circuitry.
Buck Converter
Boost Converter
:
:
V=L
dI
dt
Vo
1
=
Vi
1 D
Note: The results obtained is using Buck converter as a reference.
Refer to Appendix C – Figure 37 & 38 for the waveforms.
44
Stage 7:
As the final stage of the design where filter is being implemented to remove
the harmonics of the current waveform present at the AC source. Currently LC
filter is being used for this situation, and as to determine the reactance of the
filter in the circuit, some calculations need to be done.
Note: Now, inductance value used is 100mH, and the capacitance value used
is 100uF.
Reactance of Inductance
Reactance of Capacitance
:
2 x PI x Frequency x Inductance
=
2 x PI x 50Hz x 100mH
=
31.42ohm
:
1 / ( 2 x PI x Frequency x Capacitance )
=
1/ ( 2 x PI x 50Hz x 100uF )
=
31.83ohm
The reactance will changes whenever either of the values changes and it will
affect the output result drastically. Below is the flow of changes to be take
note when either of the parameters is being altered.
Reactance for Inductance:
(1)
When inductance decreased, the reactance will decrease.
(2)
When inductance increased, the reactance will increase.
(3)
When the frequency increased, the reactance will increase.
(4)
When the frequency decreased, the reactance will decrease.
45
Reactance for Capacitance:
(1)
When capacitance decreased, the reactance will increase.
(2)
When the capacitance increased, the reactance will decrease.
(3)
When the frequency increased, the reactance will decrease.
(4)
When frequency decreased, the reactance will increase.
Refer to Appendix C – Figure 39, 40, 41, 42, 43 & 44 for the waveforms.
46
PROBLEMS ENCOUNTERED AND SOLUTIONS
Problem 1:
Do not have the basic knowledge about switch-mode power supplies?
Solution 1:
Research on books and internet to get more information and understand it.
Problem 2:
Do not know what is voltage/current distortion?
Solution 2:
Research on books and internet to get more information and understand it. And also
approach my project supervisor for guidance.
Problem 3:
Do not have the basic knowledge on the filters, the different types of filters and what
its applications?
Solution 3:
Research on books and internet to get more information and understand it.
Problem 4:
Do not know how to use the software PSIM to do the design and simulation portion?
Solution 4:
Go online to search for the software manual and spent some time on exploring the
features of the software.
Problem 5:
During the design and simulation portion of using PSIM, found out that there is
limitation to the software where a lot of stuff can’t be fulfilled.
Solution 5:
My project supervisor request me to change the software from PSIM to LTspice, and
it takes me some time again to explore the software, by searching some information
on the internet.
47
Problem 6:
Do not have the basic knowledge in designing a switch-mode power supply circuit?
Solution 6:
Research on books and internet to find examples and understand it.
Problem 7:
Do not know what a converter is, what it does, and how many different types of
converters?
Solution 7:
Research on books and internet to get more information and understand it.
Problem 8:
During the designing portion, not able to achieve the desired output out from a simple
circuit, as nothing seems wrong?
Solution 8:
It is due to the ground symbol being placed at the wrong part of the circuit. At
different spots of the circuit, it will output different results. It is due to the software
characteristics.
Problem 9:
Spending too much time on the converter circuitry to get it work on the simulation?
Solution 9:
Moving in the wrong path as it is not a requirement to be met for the project, as the
aim is to design a filter to remove the distortion on the voltage/current waveform at
the source. In LTspice library, there are chips available being designed for converters,
and can be used as an assistant in the project. Make use of the library and move on
towards the aim of the project.
Problem 10:
After compiling the whole circuitry, the results that I get is good, but there is no
symptoms of voltage/current distortion present at the source?
48
Solution 10:
It is because the circuitry is load with a resistive load, as the software recognized it as
an ideal case. Add an inductor to the load which will make it as a resistive-inductive
load, then you will see the distortion on the current waveform at the source where
voltage waveform will not be affected at all.
Problem 11:
Performing FFT on the distortion of current waveform, the axis is being labelled as
decibels and frequency, as the output results doesn’t able to achieve something similar
to the spectrum analyzer. Refer to figure 17.
Solution 11:
There is no way to change the axis parameters, as it is one of the limitations of the
software.
Problem 12:
How to have the distortion being cleaned up and have a nice output?
Solution 12:
Try all kinds of passive filters, and compare the outputs and decide which one is the
better one for the project, understand it and able to explain why this is chosen.
49
CONCLUSION
5.1
FUTURE WORK
1.
Since there is a grounding issue on the software, as to achieve the
desired output on different nodes on the circuit maybe can break down
the circuits parts by parts to simulate or build a prototype on the
breadboard or PCB to solve the grounding problem.
2.
In order to have a better understanding on voltage/current distortion, it
is best to build a prototype, where you can easily change the load
circuit from resistive to resistive-inductive or resistive-capacitive to see
the changes of the results, as grounding issue is being resolved and
able to get a more accurate readings.
3.
For the FFT results that being obtained from the simulation, the image
does not really reflect how much harmonics is present in the circuit. It
would be best to build a prototype and tap out the signals to the
spectrum analyzer where it reflect the harmonics individually, where
shows fundamental frequency and harmonics level ( N1, N2, N3 and
so on ). It would be easily to be explained with the better image on the
spectrum analyzer. Refer to Figure 17 below.
Figure 17: Example of Harmonics Image (FFT)
50
4.
In order to have a better understanding on filters, it is best to build a
prototype, where you can easily swap the filter circuit from RC to LC
to RL and observe the changes on the distortion present at the source.
It would be nice where oscilloscope, current meter and voltage meter
are involved to collect the data as to ensure a more accurate data
collection.
Overall, building a prototype is highly recommended as it is more realistic in
life as compared to simulation where there is a certain level of limitations. It can
eliminate issue like grounding problem and so on. Another thing is that we can
achieve much more stable readings, using electronic equipments like the oscilloscope,
digital voltage multimeter, current meter and spectrum analyzer to do the job. It
would enhance better understanding of the whole project going on. And also budget
would be a factor to be considered.
5.2
SUMMARY
Generally for this project, it enhances me with a lot of knowledge and
exposure in the designing of hardware circuitry and software simulation. And also
creating a chance in allowing me to have hands on experience on how to manage a
project, improving my research skills and learn more skills.
The main portion of the project is to design a complete switch-mode power
supplies model. With minimum knowledge and experience on the designing of
hardware circuitry, I faced difficulty in the designing portion, also in the selection of
the components and the wiring connection of the circuit. In addition, I have no hands
on experience in using simulation software that made me have to start from scratch to
learn how to use it.
51
Another challenging part of the project is to implement the suitable filter onto
the circuit as to minimize the distortion on the AC current waveform as what I have
faced. In this project, I have chosen LC filter to be the better one for this scenario, and
below will be the reasons why it is chosen.
1. It is the typical filter to be used in the engineering industry.
2. The filter order is twice than other filters, which gives better performance
efficiency.
3. LC filter is lossless in terms of heat.
4. It is being designed to use for a specified source.
5. The cost of the LC filter is expensive than the rest of the filters due to the order
which provides better filtering. Refer to table 6, 7 and 8 for the cost of the
individual components, as the cost for LC is US6.05, RC is US2.70 and LR is
US4.25.
6. In terms of the results, refer to figure 50, 53 and 56, it will clearly shows that LC
filter has the better minimal harmonic level than the other two filters, RC and LR.
Overall, I have summarized the whole project objective, and fulfilled the
completion of the project.
5.3
REFLECTION
I personally feel that the project was not very successful even I have
completed the project on-time, but at least I have meet the main objectives. I am able
to design out the whole model of a switch-mode power supplies, and able to achieve
the right output waveforms during simulation. As the model is always assumed as an
ideal case, where there is no signs distortion, changes to the loads is required. That’s
what I need to see, where distortion occurs on the current waveform at the source.
And filter is implemented at the source to remove as much harmonics as possible,
before the waveform flows back to the source. That’s all about my project.
52
During the 10 months and the time that I spent in UniSIM, a lot of valuable
skills and knowledge are being picked up along the way; I become more confident in
handling problems of my project and also improved my management skill. Not
forgetting that report writing and oral presentation will greatly enhances in my future
career path, and I can say that it is a very good experience to have in order to make
my life more exciting and meaningful.
53
REFERENCES FROM INTERNET
1.
http://media.wiley.com/product_data/excerpt/43/07803539/0780353943.pdf
2.
http://en.wikipedia.org/wiki/Power_supply
3.
http://en.wikipedia.org/wiki/Electrical_power
4.
http://en.wikipedia.org/wiki/Power_supply#Linear_power_supply
5.
http://en.wikipedia.org/wiki/Switched-mode_power_supply
6.
http://en.wikipedia.org/wiki/Power_supply#Switched-mode_power_supply
7.
http://en.wikipedia.org/wiki/Voltage_source
8.
http://www.glentek.com/glentek/inddesc.aspx
9.
http://library.thinkquest.org/C006657/electronics/capacitor.htm
10.
http://www.powerdesignindia.co.in/ART_8800563065_2900003_TA_69f4082
9.HTM
11.
http://www.siemens-profibus.com/line-filter-schematic/
12.
http://www.google.com.sg/imglanding?q=diagram%20of%20step%20down%
20transformer&imgurl=http://scienceaid.co.uk/physics/electricity/images/trans
former.png&imgrefurl=http://scienceaid.co.uk/physics/electricity/electromagn
etism.html&h=321&w=400&sz=22&tbnid=ostVjboR9vW6oM:&tbnh=100&t
bnw=124&prev=/images%3Fq%3Ddiagram%2Bof%2Bstep%2Bdown%2Btra
nsformer&hl=en&usg=__qYEDU115TWhf9JncWL7futR7tBU=&ei=vPWeS4
XTFYHCrAeJyb2gDg&sa=X&oi=image_result&resnum=2&ct=image&ved=
0CBEQ9QEwAQ&start=0#tbnid=ucLhWdYo6r1lDM&start=9
13.
http://en.wikipedia.org/wiki/Transformer
14.
http://www.ehow.com/facts_5615997_diode-theory.html
15.
http://en.wikipedia.org/wiki/Rectifier
16.
http://www.ask.com/wiki/Ground_%28electricity%29
17.
http://archive.chipcenter.com/circuitcellar/october01/c1001ts2.htm
18.
http://en.wikipedia.org/wiki/Passivity_%28engineering%29
19.
http://en.wikipedia.org/wiki/RL_circuit
54
20.
21.
http://www.sweethaven.com/sweethaven/ModElec/acee/lessonMain.asp?iNum
=0402
http://en.wikipedia.org/wiki/LC_circuit
22.
http://www.advancedphysics.org/forum/archive/index.php/t-1912.html
23.
http://en.wikipedia.org/wiki/RC_circuit
24.
http://www.sweethaven.com/sweethaven/ModElec/acee/lessonMain.asp?iNum
=1002
25.
http://www.ehow.com/how_5147924_calculate-reactance.html
26.
http://www.allaboutcircuits.com/vol_2/chpt_5/4.html
27.
http://www.calculatoredge.com/electronics/reactance.htm
28.
http://www.edaboard.com/ftopic152915.html
29.
http://www.justradios.com/resorderform.html
30.
http://www.verntisdale.com/caplist.htm
31.
http://www.northcreekmusic.com/NorthCreekCoilPrices.PDF
32.
http://sg.farnell.com/toko/10rb104k/inductor-100mh/dp/1193630
33.
http://www.nxp.com/acrobat_download/applicationnotes/APPCHP2.pdf
34.
http://en.wikipedia.org/wiki/Buck_converter
35.
http://en.wikipedia.org/wiki/Boost_converter
36.
http://en.wikipedia.org/wiki/Flyback_converter
37.
http://en.wikipedia.org/wiki/Forward_converter
38.
http://www.powersimtech.com
39.
http://vidsys.com/products/what-is-psim2/
40.
http://paginas.fe.up.pt/~electro2/labs/psim-manual.pdf
41.
http://ipvideomarket.info/report/psim_problems
42.
http://www.linear.com/designtools/software/
43.
http://www.markallen.com/teaching/ucsd/147a/lectures/lecture3/3.php
55
REFERENCES FROM BOOKS
1.
Switch-Mode Power Supplies ( SPICE Simulations and Practical Designs )
Author
Loan from
2.
4.
Christophe P. Basso
Tay Eng Soon Library
Analog and Digital Filter Design ( 2nd Edition )
Author
Loan from
3.
:
:
:
:
Steve WInder
Tay Eng Soon Library
Advanced AC Electronics: Principles & Applications
Author
:
Loan from
:
J. Michael Jacob
Purdue University West Lafayette, Indiana
Tay Eng Soon Library
Schematic Capture with Cadence PSpice ( 2nd Edition )
Author
:
Loan from
:
Marc E. Herniter
Associate Professor
ECE Department
Rose-Hulman Institute of Technology
Tay Eng Soon Library
56
APPENDICES
APPENDIX A - GANTT CHART FOR PROJECT PLANNING
Month
Date
Week
Literature Review
Learning of New
Software
Understanding of
Converters Diagrams
Understanding of
Filters Diagrams
Circuit Simulation
Using Software and
Troubleshooting (If
any)
Troubleshooting
Final Evaluation
Further
Improvement
Final Report
Poster Presentation
Jul09
1-31
1-4
Aug09
1-31
5-9
Sept09
1-30
10-13
Oct09
1-31
14-18
xxxx
xxxxx
xxxxx
xxxx
xxxx
xxxxx
xxxxx
xxxx
xxxxx
xxxxx
xxxx
xxxxx
xxxx
xxxxx
Nov09
1-30
19-22
Dec09
1-31
23-27
Jan09
1-31
28-32
Feb09
1-28
3336
Mar09
1-31
37-41
Apr09
1-30
4245
May09
1-31
46-50
xxxxx
xxxx
xx
xxxxx
xxxx
xxxx
xxxxx
xxxxx
xxxx
xxxx
xxxxx
xxxx
xxxxx
xxxxx
xxxx
57
APPENDIX B – FLOW DESIGN OF THE FINALIZED SIMULATION
MODEL
Stage 1
-
AC source connect up with a resistive load
Figure 18: First stage of design
Stage 2
-
AC source connect up with a step-down transformer then to a
resistive load
Figure 19: Second stage of design
58
Stage 3
-
AC source connect up with a step-down transformer, then to a
full-wave bridge rectifier, then to a resistive load
Figure 20: Third stage of design
Stage 4
-
AC source connect up with a step-down transformer, then to a
full-wave bridge rectifier, then to a filter capacitor, then to a
resistive load
Figure 21: Fourth stage of design
59
Stage 5
-
AC source connect up with a step-down transformer, then to a
full-wave bridge rectifier, then to a filter capacitor, then to a
resistive-inductive load
Figure 22: Fifth stage of design
Stage 6
-
AC source connect up with a step-down transformer, then to a
full-wave bridge rectifier, then to a filter capacitor, then to a
DC-DC converter, then to a resistive-inductive load
Figure 23: Sixth stage of design
60
Stage 7
-
The final design of the simulation model with filter add-on
before the primary side of the transformer.
Figure 24: Seventh stage of design
61
APPENDIX C – RESULTS OF THE FINALIZED SIMULATION MODEL
Stage 1
-
AC source connect up with a resistive load
Figure 25: AC source waveform @ 230Vac
Figure 26: Current waveform flowing through the circuit @ 4.6A
62
Stage 2
-
AC source connect up with a step-down transformer then to a
resistive load
Figure 27: Voltage waveform on its secondary side of transformer @ 12Vac
Figure 28: Current waveform after the secondary side of transformer flowing
through the circuit @ 0.24A
63
Stage 3
-
AC source connect with a step-down transformer, then to a
full-wave bridge rectifier, then to a resistive load
Figure 29: Voltage waveform after the full-wave bridge rectifier @ 12Vdc
Figure 30: Current waveform after the full-wave bridge rectifier still remains as
stage 2 @ 0.24A
64
Stage 4
-
AC source connect up with a step-down transformer, then to a
full-wave bridge rectifier, then to a filter capacitor, then to a
resistive load
Figure 31: Voltage waveform after the filter capacitor where ripple is being
minimized and maintained @ 12Vdc
Figure 32: Current waveform after the filter capacitor flowing through the
circuit @ 0.24A
65
Stage 5
-
AC source connect up with a step-down transformer, then to a
full-wave bridge rectifier, then to a filter capacitor, then to a
resistive-inductive load
Figure 33: Voltage waveform after the filter capacitor remains @ 12Vdc with
load changed
Figure 34: Current waveform after the filter capacitor flowing through the
circuit @ 0.22A with load changed
66
Figure 35: AC source waveform remains unaffected after the load changed
Figure 36: Current waveform at AC source is being affected with load changed
67
Stage 6
-
AC source connect up with a step-down transformer, then to a
full-wave bridge rectifier, then to a filter capacitor, then to a
DC-DC converter, then to a resistive-inductive load
Figure 37: Input voltage waveform to the Buck converter @ 12Vdc
Figure 38: Output voltage waveform after the Buck converter @ 5Vdc
68
Stage 7
-
The final design of the simulation model with filter add-on
before the primary side of the transformer.
Figure 39: AC source waveform @ 230Vac before filter is being implemented
Figure 40: Current waveform at AC source is being distorted when the circuit is
compiled together and happens before filter is being implemented
Figure 41: FFT results of the current waveform at AC source is being distorted
69
Figure 42: AC source waveform @ 230Vac remains unchanged after filter is
being implemented
Figure 43: Current waveform at AC source is being cleaned up after filter is
being implemented
Figure 44: FFT results of the current waveform at AC source is being cleaned up
70
APPENDIX D – DESIGN OF OTHER FILTERS SIMULATION MODEL
LC Filter Model ( The chosen one ):
Figure 45: LC Filter Simulation Model
RC Filter Model:
Figure 46: RC Filter Simulation Model
LR Filter Model:
Figure 47: LR Filter Simulation Model
71
APPENDIX E – RESULT OF OTHER FILTERS SIMULATION MODEL
LC Filter Results ( The chosen one ):
Figure 48: AC Voltage waveform @ the source after LC filter is implemented
Figure 49: AC Current waveform @ the source is being cleaned up after LC
filter is implemented
Figure 50: FFT of the AC Current waveform @ the source
72
RC Filter Results:
Figure 51: AC Voltage waveform @ the source after RC filter is implemented
Figure 52: AC Current waveform @ the source is being cleaned up after RC
filter is implemented
Figure 53: FFT of the AC Current waveform @ the source
73
LR Filter results:
Figure 54: AC Voltage waveform @ the source after LR filter is implemented
Figure 55: AC Current waveform @ the source is being cleaned up after filter is
implemented
Figure 56: FFT of the AC Current waveform @ the source
74