1. 1
PROJECT REPORT
On
A FAMILY OF SOFT-SWITCHING DC-DC CONVERTERS
BASED ON A PHASE-SHIFT-CONTROLLED ACTIVE
BOOST RECTIFIER
Submitted in partial fulfillment for the award of the degree
Of
BACHELOR OF TECHNOLOGY
In
ELECTRICAL AND ELECTRONICS ENGINEERING
By
TUSHAAR JAIN K 1051220086
RAJNISH KUMAR GIRI 1051220119
DEBASHISH GORAI 1051220126
SHAKSHI KUMARI 1051220127
Under the guidance of
Mr K.SURENDHIRA BABU, M.TECH.,
(Assistant Professor, Department of Electrical and Electronics Engineering)
FACULTY OF ENGINEERING AND TECHNOLOGY
SRM UNIVERSITY
(Under section 3 of UGC Act, 1956)
RAMAPURAM CAMPUS, Chennai – 600089.
May, 2016
2. 2
SRM UNIVERSITY
(Under Section 3 of UGC Act, 1956)
BONAFIDE CERTIFICATE
Certified that this project report titled “A FAMILY OF SOFT-SWITCHING DC-DC
CONVERTERS BASED ON A PHASE-SHIFT-CONTROLLED ACTIVE BOOST
RECTIFIER” is the bonafide work of ―TUSHAAR JAIN K -1051220086, RAJNISH
KUMAR GIRI -1051220119, DEBASHISH GORAI -1051220126, SHAKSHI KUMARI -
1051220127‖ , who carried out the project work under my supervision. Certified further, that
to the best of my knowledge the work reported herein does not form any other project report
or dissertation on the basis of which a degree or award was conferred on an earlier occasion
on this or any other candidate.
SIGNATURE SIGNATURE
Mr. K.SURENDHIRA BABU, M.TECH Dr. B.RAMPRIYA
GUIDE HEAD OF THE DEPARTMENT
Assistant Professor Dept. of Electrical and Electronics
Dept. of Electrical and Electronics Engineering
Engineering
Signature of the Internal Examiner Signature of the External Examiner
3. 3
ACKNOWLEDGEMENT
We place on regard our deep sense of gratitude to our beloved Chancellor Dr.
T.R.PACHAMUTHU, for providing us with the requisite infrastructure throughout the
course.
We take the opportunity to extend our hearty thanks to our Chairman, Dr.
R.SHIVAKUMAR, for his constant encouragement.
We convey our sincere thanks to our Dean Dr. SUBBIAH BHARATHI, for his
interest and support.
We convey our sincere thanks to our Vice Principal Dr. L.ANTONY MICHAEL
RAJ, for his interest and support.
We take the privilege to extend our hearty thanks to the HEAD OF DEPARTMENT,
EEE Dr. B.RAMPRIYA for her suggestions, support and encouragement towards the
completion of the project with perfection.
We thank our Project Coordinator Dr. B.RAMPRIYA, Mr. M.MOOVENDAN and
internal guide Mr. K.SURENDHIRABABU for their timely help and guidance throughout
the overall process of the project.
We would like to express our sincere thanks to all of our staff members of the
Department of Electrical and Electronics who gave many suggestions from time to time that
made our project work better and well finished.
Last but not the least; we would like to thank our parents and friends for the supports,
concerns and prayers, which were a major factor in the completion of this project.
As everything begins and ends with God, we conclude this acknowledgement by
thanking God for everything.
4. 4
ABSTRACT
This paper is enhance the high efficiency and high power of the system by using
Phase shift controlled ABR (Active Boost Rectifier). Basically, an ABR is composed of a
traditional diode rectifier and a bidirectional switch. By adopting phase-shift control between
the primary- and secondary-side switches, the output voltage regulation can be achieved
when introducing the ABR to a dc–dc transformer. When the proposed converter operates in
the soft-switching continuous conduction mode, zero-voltage switching (ZVS) performance
for all the primary- and secondary side switches is achieved. When the proposed converter
operates in the soft-switching continuous conduction mode, zero-voltage switching (ZVS)
performance for all the primary- and secondary side switches is achieved. When the converter
operates in the discontinuous conduction mode, zero current switching (ZCS) for the
primary-side switches and ZVS for the secondary-side switches are achieved. Furthermore,
the diode reverse-recovery problem is alleviated by employing the ABR and phase-shift
control scheme.
5. 5
TABLE OF CONTENTS
CHAPTER-1 INTRODUCTION...................................................................................... 11
1.1 Introduction ............................................................................................................ 11
CHAPTER-2 SYSTEM DESIGN..................................................................................... 13
2.1 Existing System....................................................................................................... 13
2.1.1 Description ...................................................................................................... 13
2.1.2 Demerits.......................................................................................................... 13
2.2 Proposed System..................................................................................................... 14
2.2.1 Description...................................................................................................... 14
CHAPTER-3 MODES OF OPERATION…………………………………………............15
3.1 Proposed dc-dc converters based on ABR…………………......................................15
3.1.1 Concept of an ABR………………………………………………………..…...15
3.1.2 Family of DC–DC Converters Based on ABR…………………………..…….16
3.2 Analysis on the FBC with voltage doubler ABR……………………………..…….17
‗ 3.2.1 Output Characteristics…………………….……………………………………17
3.2.2 Soft-Switching Characteristics……………………………....……..………….17
CHAPTER-4 HARDWARE REQUIREMENT…………………………….……………..19
4.1 Regulated power supply…….…………………………..…………………………19
4.1.1 Ordinary dc power supply…………………………………………………….19
4.1.2 Important terms……………………………………………………………….19
‗ 4.1.3 Need of regulated power supply………………………………..….…………20
4.1.4 Schematic circuit diagram of RPS…………………………………………….21
4.2 Transformer……………………………………………………………………….21
4.2.1 Single phase equivalent circuit of power transformer………………………..21
4.2.2 Efficiency…………………………………………………………………….22
4.2.3 Open-circuit test……………………………………………………………...23
4.2.4 Short-circuit test……………………………………………………………...23
4.3 Filter………………………………………………………………………………24
4.3.1 Introduction…………………………………………………………………..24
4.3.2 The basic filter types…………………………………………………………25
4.3.3 Description of filter…………………………………………………………..27
6. 6
4.4 Zero crossing detector……………………………………………………………...28
4.4.1 Introduction…………………………………………………………………...28
4.4.2 Zero crossing measurement techniques……………………………………....28
4.4.3 Block diagram of zero-crossing detector……………………………………..32
4.5 PIC Microcontroller……………………………………………………………….32
4.5.1 Overview……………………………………………………………………...32
4.5.2 Salient Feature…………………………………………………………………33
4.5.3 Architecture……………………………………………………………………34
4.5.4 Addressing Modes……………………………………………………………..38
4.5.5 Microcontroller features……………………………………………………….39
4.5.6 Pin diagram…………………………………………………………………….40
4.6 Analog to digital converters………………………………………………………...42
4.6.1 Introduction…………………………………………………………………….42
4.6.2 Application of ADC……………………………………………………………42
4.7 Project figure…………..…………………………………………………….43
CHAPTER-5 SOFTWARE REQUIREMENTS …………………………………………44
5.1 MATLAB ................................................................................................................... 44
5.1.1 Introduction......................................................................................................... 44
5.1.2 Key features………………………………………………………………………..45
5.2 SIMULINK MODEL ................................................................................................. 45
5.2.1 Introduction……………………………………………………………………….45
5.2.2 Key features……………………………………………………………………….45
5.2.3 Creating and working with models……………………………………………….46
5.2.4 Building and editing a model……………………………………………………..47
5.3 SIMULATION RESULTS ........................................................................................ 48
5.3.1 Existing Simulink model………………………………………………………….48
5.3.2 Proposed Simulink model ………………………………………………………...54
8. 8
LIST OF FIGURES
FIGURE
NO. FIGURE TITLE PAGE
2.1 EXISTING SYSTEM 13
2.2 PROPOSED SYSTEM 14
3.1 TOPOLOGY OF ABR 15
3.2 DERIVED ABR TOPOLOGY FOR RECTIFIER 15
3.2 REALIZATIONS OF SWITCH 16
3.3 DERIVED ABR TOPOLOGIES 16
3.4 SIMPLIFIED FULL-BRIDGE ABR 16
3.5 DC-DC CONVERTER TOPOLOGY 17
3.6 OUTPUT CHARACTERISTICS 17
3.7 CONTROL BLOCK DIAGRAM 18
3.8 COMPARISON B/W CONVERTERS 18
4.1 ORDINARY DC POWER SUPPLY 19
4.2 VOLTAGE REGULATION GRAPH 20
4.3 SCHEMATIC CIRCUIT OF +5V POWER SUPPLY 21
4.4 IC LM7805 21
4.5 WORKING MODEL OF TRANSFORMER 22
9. 9
4.6 EQUIVALENT CIRCUIT 22
4.7 OPEN CIRCUIT TEST 24
4.8 SHORT CIRCUIT TEST 24
4.9 BANDPASS FILTER AMPLITUDE RESPONSE 26
4.10 GRAPH OF BAND PASS FILTER 26
4.11 SIMPLE HIGH-PASS FILTER 26
4.12 HIGH-PASS FILTER GRAPH 27
4.13 HIGH-PASS FILTER AMLITUDE RESPONSE 27
4.14 FILTERING SIGNAL FOR HPF 29
4.15 FREQUENCY VS PHASE RESPONSE OF HPF 30
4.16 CIRCUIT DIAGRAM FOR INTERPOLATION METHOD 31
4.17 OSCILLOSCOPE CAPTURE OF ZERO-CROSSING DETECTOR 31
4.18 BLOCK DIAGRAM OF ZERO-CROSSING DETECTOR 32
4.19 PROGRAM MEMORY 36
4.20 ARCHITECTURE OF PIC 16F887 MICROCONTROLLER 37
4.21 DIRECT ADDRESSING MODE 38
4.22 PIN DIAGRAM 40
4.23 PIC 16F887 40-PIN DETAILS 41
4.24 PROJECT FIGURE 43
5.1 SIMULINK MODEL 46
5.2 BUILDING A MODEL 47
5.3 SIMULATION DIAGRAM FOR EXISTING SYSTEM 48
5.4 INPUT VOLTAGE 48
10. 10
5.5 INPUT CURRENT 49
5.6 INPUT POWER 49
5.7 OUTPUT VOLTAGE 50
5.8 OUTPUT CURRENT 50
5.9 OUTPUT POWER 51
5.10 EXISTING EFFICIENCY 51
5.11 SIMULATION DIAGRAM FOR PROPOSED SYSTEM 52
5.12 INPUT VOLTAGE 52
5.13 INPUT CURRENT 53
5.14 INPUT POWER 53
5.15 OUTPUT VOLTAGE 54
5.16 OUTPUT CURRENT 54
5.17 OUTPUT POWER 55
5.18 PROPOSED EFFICIENCY 55
12. 12
rights reserved. ISSN: 1992-8645 www.jatit.org E-ISSN: 1817-3195 631 reduce voltage
stress. However, they will result in high input current ripple and require relatively large input
and output filters. A passive lossless clamped circuit can recover the energy that is trapped in
the leakage inductor and reduce voltage spike, but the active switch is still in hard switching.
The additional snubbers are required to reduce the voltage stresses of switches. In order to
raise the efficiency and increase power conversion density, the soft-switching technique is
required in dc/dc converters. The high switching frequency used in static power converters
can reduce the weight and size of the passive components. However, the switching losses on
power semiconductors are also increased.
The soft-switching techniques with variable switching frequency have been
proposed to increase the switching frequency, reduce the size of power converters, and
reduce the switching losses of the switching devices. The asymmetrical pulse width
modulation (PWM) techniques were proposed in to achieve the zero-voltage switching (ZVS)
feature at the power switch turn on instant. The active clamp techniques were presented in to
achieve ZVS turn-on. Switching mode power supplies based on the flyback converter were
widely used in industrial products for low-power applications. In the flyback converter, the
transformer is adopted to achieve circuit isolation and energy storage. The zeta converters
have been studied in to provide the isolated output voltage or achieve power factor
correction. However, the power switch is operated in hard-switching PWM so that the circuit
efficiency is low. The zeta converters with zero-current switching or ZVS technique have
been proposed to reduce converter volume, voltage stresses of switching devices, and
switching losses. An asymmetrical interleaved high step-up converter that combines the
advantages of the aforementioned converters is proposed, which combined the advantages of
both. In the voltage multiplier module of the proposed converter, the turn‘s ratio of coupled
inductors can be designed to extend voltage gain, and a voltage-lift capacitor offers an extra
voltage conversion ratio.
Multi cascaded sources arrangement and this topology the source series from another
source attached to a basic dc/dc converter is used to supply load power. Moreover a fraction
of power from the source is passed through the converter suffering from conversion losses,
and the remain power is supplied directly to the output load that does not have any power
loss. Therefore, the source cascaded topology can achieve high-efficiency and high-voltage
gains. In addition, due to this cascaded characteristics, the volume of transformer based on
the voltage and current stress on some components of the basic converter, can likewise be
reduced.
13. 13
CHAPTER-2
SYSTEM DESIGN
2.1 EXISTING SYSTEM:
Fig 2.1 Topology of a Full-bridge converter with VD rectifier.
2.1.1 DESCRIPTION
In existing system, there are four bidirectional switches which are connected in the
primary side of the transformer.
It consists of rectifier, dc-dc converters, two diodes, one leakage inductor
And two capacitor.
230v ac supply is given to this system then rectifier converts into approx. 60v dc
supply.
After this conversion, two bidirectional switches are start working they are basically
S1&S4 and S2&S3.
DC-DC converter converts pulsating dc into continuous dc supply which are
measured by load.
2.1.2 DEMERITS
Soft switching techniques is not implemented i.e. ZCS (Zero current switching)
and ZVS (Zero voltage switching).
Poor voltage regulation.
Low torque.
Low efficiency.
14. 14
2.2 PROPOSED SYSTEM:
Fig 2.2 New Full Bridge converter with VD ABR.
2.2.1 DESCRIPTION:
In proposed system, ABR is introduced to the secondary side of the transformer.
An ABR is composed of a traditional diode rectifier & a bidirectional switch.
By adopting phase shift control b/w the primary & secondary side switches, the
output voltage regulation can be achieved when introducing the ABR to a DC-DC
T/F.
When the proposed converter operates in the soft-switching continuous conduction
mode, zero- voltage switching (ZVS) performance for all the primary and secondary
side switch is achieved.
When the converter operates in the discontinuous conduction mode, zero current
switching(ZCS) for all primary side switches & zero voltage switching (ZVS) for
all the secondary side switches are achieved.
The diode reverse recovery problem is alleviated by employing the ABR & phase-
shift control scheme.
It is easy to understand that the output voltage of a DC T/F can be controlled by
improving the uncontrolled diode rectifier to an ABR.
15. 15
CHAPTER-3
MODES OF OPERATION
3.1 Proposed dc-dc converters based on ABR:
3.1.1 Concept of an ABR:
When this converter operates as a dc transformer, the duty cycles of all the switches
are fixed at 0.5. The voltage-source full-bridge inverter, which is composed of a dc input
voltage source Uin and four switches S1 − S4, generates an ac square-wave voltage uP ,
applying to the primary winding of the transformer. Therefore, the converter shown in Fig. 1
can be represented by the one shown in Fig. 2(a). For simplicity, considering an ideal
transformer T with turns a ratio of 1, this circuit can be further simplified to a uncontrolled
rectifier.
Fig 3.1 Topologies of ABR derived from (a) full-bridge and (b) center-tapped diode-
rectifiers.
Fig 3.2 (a)–(c) Realizations of bidirectional switch and (d) unidirectional switch.
Fig 3.3 Derived ABR topologies (a) voltage-doubler, (b)full-bridge, and (c)center-tapped.
16. 16
Fig 3.4 Simplified full-bridge ABR.
3.1.2 Family of DC–DC Converters Based on ABR:
A bidirectional switch can be realized through the combination of MOSFETs and
diodes, while a unidirectional switch can be realized through a series connection of a
MOSFET and a diode. Some possible realizations of the bidirectional and unidirectional
switches are illustrated in Fig. 6. Based on these switches, a family of ABR circuits can be
derived.
On the other hand, full-bridge diode rectifier, a bidirectional switch which is
paralleled with the transformer winding can also be built by replacing the two diodes in the
rectifier with two MOSFETs. As a result, simplified full-bridge ABR topologies can be
derived and shown in Fig. 8, where the bidirectional switches have been highlighted with red
color.
Fig 3.5 New DC-DC converter topologies based on the ABRs.
17. 17
3.2 Analysis on the FBC with voltage doubler ABR:
3.2.1 Output Characteristics:
Fig 3.6 Output characteristics: (a) normalized output power versus duty cycle and (b)
voltage gain versus duty cycle.
Fig 3.7 Control block diagram.
3.2.2 Soft-Switching Characteristics:
According to the operation principles of the converter, the ZVS turn ON of all the
primary-side power MOSFETs can be achieved when the converter operates in the SS-CCM
and HSCCM modes. The ZVS turn OFF of primary side MOSFETs can also be obtained
thanks to the parasitic or parallel capacitors on the drain to source of MOSFETs. When the
converter operates in the SS-CCM, ZVS turn ON of the secondary-side MOSFETs and zero
current switching (ZCS) turn OFF of rectifier diodes can also be achieved. However, when
the converter operates in HS-CCM, soft switching of secondary-side devices will lost. But, it
should be noted that, the turn-off loss of the secondary side MOSFETs can be minimized in
18. 18
the HS-CCM because the turn-off current is the minimum of these three operation modes
under the same output power condition.
Fig 3.8 Performance comparison between the proposed FBC-VD-ABR the conventional
phase- shift full bridge converter, and the full-bridge LLC resonant converter.
19. 19
CHAPTER-4
HARDWARE REQUIREMENT
4.1 Regulated power supply
4.1.1 Ordinary dc power supply:
These variations in dc output voltage may cause inaccurate or erratic operation or
even malfunctioning of many electronic circuits. For example, in an oscillator, the frequency
will shift and in transmitters, distorted output will result. Therefore, ordinary power supply is
unsuited for many electronic applications and is being replaced by regulated power supply.
4.1.2 Important terms:
For comparison of different types of power supplies, the following terms are commonly
used.
(i) Voltage regulation. The dc voltage available across the output terminals of a given
power supply depends upon load current. If the load current Idc is increased by decreasing RL
(See Fig. 17.2), there is greater voltage drop in the power supply and hence smaller dc output
voltage will be available. Reverse will happen if the load current decreases. The variation of
output voltage w.r.t. the amount of load current drawn from the power supply is known as
voltage regulation and is expressed by the following relation.
VNL
−V FL
×100
% Voltage regulation = VFL
Where VNL = dc output voltage at no-load
VFL = dc output voltage at full-load
Fig 4.1 Ordinary DC power supply.
20. 20
In a well-designed power supply, the full-load voltage is only slightly less than no-load
voltage i.e. voltage regulation approaches zero. Therefore, lower the voltage regulation, the
lesser the difference between full-load and no-load voltages and better is the power supply.
Power supplies used in practice have a voltage regulation of 1% i.e. full-load voltage is
within 1% of the no-load voltage. Fig. 17.3 shows the change of dc output voltage with load
current. This is known as voltage regulation curve.
Note. The above voltage regulation is called load regulation because it indicates the
change in output voltage due to the change in load current. There is another type of voltage
regulation, called line regulation and indicates the change in output voltage due to the change
in input voltage.
(ii) Minimum load resistance. The change of load connected to a power supply varies
the load current and hence the dc output voltage. In order that a power supply gives the rated
output voltage and current, there is minimum load resistance allowed.
4.1.3 Need of regulated power supply:
In practice, there are considerable variations in ac line voltage caused by outside
factors beyond our control. This changes the dc output voltage. Most of the electronic
circuits will refuse to work satisfactorily on such output voltage fluctuations. This
necessitates to use regulated dc power supply.
The internal resistance of ordinary power supply is relatively large (> 30 Ω).
Therefore, output voltage is markedly affected by the amount of load current drawn from the
supply. These variations in dc voltage may cause erratic operation of electronic circuits.
Fig. 4.2
Load
21. 21
4.1.4 Schematic circuit diagram of RPS:
Fig 4.3 Schematic circuit of +5V power supply
A power supply circuit was needed to provide power to logic level components as
well as other components that were unable to operate from the 42-volt supply rail. The gate
drive circuitry, signal amplifier, and Hall Effect sensors required 12 volts to operate while all
of the digital hardware needed 5V. To make a +5V power supply, we use a LM7805 voltage
regulator IC is shown below.
Fig 4.4 IC LM7805
4.2 Transformer:
4.2.1 Single phase equivalent circuit of power transformer:
A transformer is a static piece of which electric power in one circuit is
transformed into electric power of same frequency in another circuit. It can raise or lower the
voltage in a circuit but with corresponding decrease or increase in current.
22. 22
Fig 4.5 Working model of transformer
Fig 4.6 Equivalent circuit of single phase transformer
4.2.2 Efficiency:
As always, efficiency is defined as power output to power input ratio.
Efficiency = Pout /Pin 100 %
Pin = Pout + Pcore + Pcopper
Pcopper represents the copper losses in primary and secondary windings. There are no
rotational losses.
23. 23
4.2.3 Open-circuit test:
Fig 4.7 Open-circuit test.
Secondary (normally the HV winding) is open, that means there is no load across
secondary terminals; hence there is no current in the secondary. Winding losses are
negligible, and the source mainly supplies the core losses, Pcore.
4.2.4 Short-circuit test:
Fig 4.8 Short-circuit test.
Secondary (normally the LV winding) is shorted, that means there is no voltage across
secondary terminals but a large current flow in the secondary. Test is done at reduced voltage
(about 5% of rated voltage) with full-load current in the secondary. So, the ammeter reads
full-load current, wattmeter reads winding losses, voltmeter reads primary voltage.
24. 24
4.3 Filter:
4.3.1 Introduction:
Filters of some sort are essential to the operation of most electronic circuits.
It is therefore in the interest of anyone involved in electronic circuit design to have the
ability to develop filter circuits capable of meeting a given set of specifications.
Unfortunately, many in the electronics field are uncomfortable with the subject, whether
due to a lack of familiarity with it, or a reluctance to grapple with the mathematics
involved in a complex filter design. This Application Note is intended to serve as a very
basic introduction to some of the fundamental concepts and terms associated with filters.
It will not turn a novice into a filter designer, but it can serve as a starting point for those
wishing to learn more about filter design. In circuit theory, a filter is an electrical network
that alters the amplitude and/or phase characteristics of a signal with respect to frequency.
Ideally, a filter will not add new frequencies to the input signal, nor will it change the
component frequencies of that signal, but it will change the relative amplitudes of the
various frequency components and/or their phase relationships.
Filters are often used in electronic systems to emphasize signals in certain
frequency ranges and reject signals in other frequency ranges. Such a filter has a gain
which is dependent on signal frequency. As an example, consider a situation where a
useful signal at frequency f1 has been contaminated with an unwanted signal at f2. If the
contaminated signal is passed through a circuit (Figure1) that has very low gain at f2
compared to f1, the undesired signal can be removed, and the useful signal will remain.
Note that in the case of this simple example, we are not concerned with the gain of the
filter at any frequency other than f1 and f2. As long as f2 is sufficiently attenuated relative
to f1, the performance of this filter will be satisfactory. In general, however, a filter‘s gain
may be specified at several different frequencies. Since filters are defined by their
frequency-domain effects on signals, it makes sense that the most useful analytical and
graphical descriptions of filters also fall into the frequency domain. Thus, curves of gain
vs frequency and phase vs frequency are commonly used to illustrate filter characteristics,
and the most widely-used mathematical tools are based in the frequency domain. The
frequency-domain behavior of a filter is described mathematically in terms of its transfer
function or network function. This is the ratio of the Laplace transforms of its output and
input signals. The transfer function defines the filter‘s response to any arbitrary input
signal, but we are most often concerned with its effect on continuous sine waves.
25. 25
Especially important is the magnitude of the transfer function as a function of frequency,
which indicates the effect of the filter on the amplitudes of sinusoidal signals at various
frequencies. Knowing the transfer function magnitude (or gain) at each frequency allows
us to determine how well the filter can distinguish between signals at different
frequencies. The transfer function magnitude versus frequency is called the amplitude
response or sometimes, especially in audio applications, the frequency response.
Similarly, the phase response of the filter gives the amount of phase shift
introduced in sinusoidal signals as a function of frequency. Since a change in phase of a
signal also represents a change in time, the phase characteristics of a filter become
especially important when dealing with complex signals where the time relationships
between signal components at different frequencies are critical.
4.3.2 The basic filter types:
Band pass:
There are five basic filter types (bandpass, notch, low-pass, high-pass, and all-pass).
The filter used in the example in the previous section was a bandpass. The number of
possible bandpass response characteristics is infinite, but they all share the same basic form.
Several examples of bandpass amplitude response curves are shown in Figure 5. The curve in
5(a) is what might be called an ‗‗ideal‘‘ bandpass response, with absolutely constant gain
within the passband, zero gain outside the passband, and an abrupt boundary between the
two. This response characteristic is impossible to realize in practice, but it can be
approximated to varying degrees of accuracy by real filters. Curves (b) through (f) are
examples of a few bandpass amplitude response curves that approximate the ideal curves
with varying degrees of accuracy. Note that while some bandpass responses are very smooth,
other have ripple (gain variations in their passbands. Other have ripple in their stopbands as
well. The stopband is the range of frequencies over which unwanted signals are attenuated.
Bandpass filters have two stopbands, one above and one below the passband.
26. 26
Fig 4.9 Examples of Bandpass Filter Amplitude Response
Fig 4.10
High-Pass:
The opposite of the low-pass is the high-pass filter, which rejects signals below its
cutoff frequency. A high-pass filter can be made by rearranging the components of our
example network as in Figure12. Note that the amplitude response of the high-pass is a
‗‗mirror image‘‘ of the low-pass response.
TL/H/11221–7
(a) (b) (c)
TL/H/11221–8
27. 27
Fig 4.11 Example of Simple High-Pass Filter
Fig 4.12
Fig 4.13 Examples of High-Pass Filter Amplitude Response Curves
4.3.2 Description of filter:
Filtering should be done in order to reduce the harmonics and ripples. For this
purpose we use capacitors for the filtering. They are rated at 100 v. here output voltage from
rectifier is 100 v. the capacitors are used in two arms. They share this voltage equally. The
capacitors are therefore rated at 100micro F/100v. Each of the capacitors shares 50v. The
capacitors are electrolytic in nature. Low-pass filters are used whenever high frequency
components must be removed from a signal. An example might be in a light-sensing
instrument using a photodiode. If light levels are low, the output of the photodiode could be
TL/H/11221–22
(a) (b) (c)
TL/H/11221–23
28. 28
very small, allowing it to be partially obscured by the noise of the sensor and its amplifier,
whose spectrum can extend to very high frequencies. If a low-pass filter is placed at the
output of the amplifier, and if its cutoff frequency is high enough to allow the desired signal
frequencies to pass, the overall noise level can be reduced.
4.4 Zero crossing detector:
4.4.1 Introduction:
As we are using non-linear loads that is both ac and dc loads the load current will be
distorted. This in turn affects the supply voltage. This will end by providing multiple zero
crossings at the voltage waveforms. So in order to find the accurate amount of magnitude of
filter current and its phase angle, we need to know whether the current is lagging or leading.
For that we go for synchronous circuit. It does consist of two low pass filter circuits; all pass
filters and a zero crossing circuit.
The multiple zero crossings caused by the harmonic current, if it is lesser we can use
only one second order low pass filter or else for severe cases we use two such filters. After
that the ripples may also be caused by the second order low pass filter, will be eliminated by
the all pass filter. Then the voltage wave is fed to the ZCD circuit. The ZCD will provide an
uprising pulse for positive rising voltage and down going pulses for negative voltage.
Zero crossing is the point of choice for measuring phase and frequency. The
reference is usually easy to establish and the signal‘s amplitude rate of change is maximum at
signal zero. Phase synchronized triggering requires placing additional constraints on zero
crossing detection. Weidenburg reviewed several method for synchronizing for firing
thyristor based power converters and proposed adaptive online waveform reconstruction. It
describes a predictive digital filter for noise reduction. Depending upon the frequency for a
particular application and the degree of signal processing, these methods can require high-
speed processing components that are too expensive for low cost applications.
4.4.2 Zero crossing measurement techniques:
Whether measuring period, frequency, or phase, the sources of errors are the
same. When measuring a signal for the purposes of synchronization, fast and accurate
frequency measurements are required. This requirement also translates into low phase
distortion that can be introduced by frequency filtering and by measurement delays. The
purpose of the instrumentation circuits and techniques discussed below are to reduce
29. 29
frequency errors due to multiple zero crossings (more than two per period) and reduce phase
errors by advanced or delayed zero crossing.
Methods that require extensive processing have significant time delays from when
changes of input frequency occur to when the change is reflected on the output. For this
reason, methods described in this paper exclude highly computational methods including
DFT and Wavelet type algorithms. The discussion methods is limited here to hardware and
combined hardware and software techniques with low process delay. Although these methods
can be applied to any frequency, the discussion here focuses on electric power system
applications.
A. Pre-Detection Low Pass filtering
Low pass filtering or band pass filtering helps to restrict the bandwidth to the
frequencies close to the frequency of the signal being measured. This technique is well suited
for signals that are expected to have small deviations about a nominal fixed frequency. It is
also well suited for signals corrupted by harmonics or other periodic signals that are
sufficiently distinguishable from the signal of interest.
A simple first order filter that can be constructed with a resistor and capacitor is
effective in reducing noise as shown in Fig. 1. The magnitude and phase response for a first-
order low pass filter is shown in Fig. 2. The cutoff frequency for this filter is set for 600 Hz.
Although the filter has little effect on the amplitude, there is significant phase shift at 60 Hz
as shown in Fig. 1 which is predictable from the phase at 60 Hz on the filter‘s Bode plot
shown in Fig. 2.
Higher order filters can appear to have zero phase shift but in reality, such filters
merely have phase shifts of integer multiples of 360 degrees. This is true for both analog and
digital filters. For digital filters, the phase delay is compounded by process delays. Filter
phase delay can be compensated for mathematically if the filters characteristics are
predictable. Unfortunately, filters constructed from physical resistors and capacitors have
low accuracy, repeatability, and temperature stability. For the filter design used in this
example, the phase shift is highly dependent on the frequency. This dependency further
complicates phase compensation techniques. As the cutoff frequency is increased, the phase
shift from filtering is less dependent on a specific frequency but the filters effectiveness for
noise reduction is likewise reduced.
30. 30
Fig 4.14 Filtering signal to eliminate noise
Fig 4.15 Frequency and phase response of a 1st
order Butterworth filter with cutoff at 600
Hz.
B. Post Processing Signal Conditioning:
Multiple outputs for a single zero crossing must be expected in designs requiring
accuracy and precision. Digital processing of the output signal does present significant
advantages. There are two approaches: rule based and digital filtering. Rule based design
eliminates events that don‘t meet expected timing requirements. This approach inhibits zero
crossing detection for a specified period after an earlier detection event. This approach relies
on the statistical probability that the next zero crossing will be close to the next half period.
The inhibit period must be constrained to allow natural variations in the input signal.
Digital filtering has the ability to discriminate events based upon frequency of
occurrence just as passive filtering but overcomes their disadvantages by having high
accuracy and predictability. Such a method is the software implementation of a phase locked
loop (PLL) with feed-forward control described by Wall and Hess. The phase locked loop
does compensate for advanced or delayed zero crossing detection due to noise and even, to a
degree, that which is caused by harmonic or alien signal corruption. There is a compromise
between the degree of rejection and the speed of adapting to new steady state conditions.
31. 31
There is no phase error because of the nature of the phased locked loop. Capture and lock
dynamics can be dynamically changed if the PLL is implemented in software. Implementing
a feed-forward algorithm increases the filter‘s response to changes in input frequency.
The software implementation of the PLL is a second order digital filter and requires
minimal processor capability. The Microchip PIC16C73B, a microcontroller with 4K word
program memory and 192 byte RAM, is sufficient to execute the PLL algorithm. Thus it
remains a low cost implementation.
C. Zero-Crossing Detection by Interpolation:
The implementation used in this design identifies two points on the sine wave: the
first just before the positive going zero crossing and the second just after the same zero
crossing. This implementation uses two optoisolators as shown in Fig. 3 to compensate for
variations in level sensitivity and switching time delays. Optoisolators with Schmitt triggered
outputs are used to provide additional hysteresis.
Input signals with constant frequency render delays due to optoisolator output
switching indistinguishable from delays due to threshold levels. The interpolation method
requires additional processor resources to accurately determine when two events occur. This
usually requires that the processor have interrupt capability and capture and compare
resources. The processor is programmed to capture the time of the times when Out-
optoisolator output goes high and the Out+ optoisolator output goes low. The true zero
crossing is computed by linear interpolation between these two times. Fig. 4 shows that this
method results in an improved degree of accuracy. The Est. Zero shown in Fig. 4 is
computed from the phase-locked loop algorithm that estimates the next zero crossing time.
Fig 4.16 Circuit for dual point interpolation method for detecting a zero crossing.
V+5
+5 V
Out+
Out
D1
D2
R1
R2
U1
U2
32. 32
Fig 4.17 Oscilloscope capture of the sine wave signal, optoisolator outputs and
computed zero crossing.
4.4.3 Block diagram of zero-crossing detector:
Fig 4.18 Block diagram of Zero Crossing Detector circuit
4.5 PIC Microcontroller:
The term PIC stands for Peripheral Interface Controller .It is the brain child of
Microchip Technology, USA. Originally this was developed as a supporting device for PDP
computers to control its peripheral devices, and therefore named as PIC, Peripheral Interface
Controller. They have coined this name to identify their single chip micro controllers. These
8-bit micro controllers have become very important now -a -days in industrial automation and
embedded applications etc. One of the earlier versions of PIC Microcontrollers is
PIC16C6x/7x. The 7x family has an enhancement of Analog to Digital converter capability.
These cs are available with a range of capabilities packaged in both dual in-line (DIP)
packages and surface-mount packages. These are available in 28 pin DIP, 40 pin DIP, 44 pin
33. 33
surface mount package…etc. some of PIC controllers contain the letter A in their number.
The presence of A indicates the brown-out reset feature, which causes a reset of the PIC
when the Power Supply voltage drops below 4.0v.
4.5.1 Overview:
The PIC 16F8XX Microcontrollers are basically RISC microcontrollers with very
small instruction set of only 35 instructions and a two-stage pipeline concept fetch and
execution of instructions. As a result, all instructions execute in a single cycle except for
program branches. There are four devices in 16F8xx family, PIC16F873, PIC16F874,
PIC16F876 and PIC16F877.The PIC16F876/873 devices come in 28-pin packages and the
PIC16F877/874 devices come in 40-pin packages. The Parallel Slave Port is not implemented
on the 28-pin devices.
PIC 16F877 is a 40-pin 8-Bit CMOS FLASH Microcontroller. The core architecture
is high-performance RISC CPU. Since it follows the RISC architecture, all single cycle
instructions take only one instruction cycle except for program branches which take two
cycles. 16F877 comes with 3 operating speeds with 4, 8, or 20 MHz clock input. Since each
instruction cycle takes four operating clock cycles, each instruction takes 0.2 μs when 20MHz
oscillator is used. It has two types of internal memories .One is program memory and the
other is data memory. Program memory is provided by 8K words (or 8K*14 bits) of FLASH
Memory, and data memory has two sources. One type of data memory is a 368-byte RAM
(random access memory) and the other is256-byte EEPROM (Electrically erasable
programmable ROM).The core features include interrupt up to 14 sources, power saving
SLEEP mode, a single 5V supply and In-Circuit Serial Programming (ICSP) capability.
The sink/source current, which indicates a driving power from I/O port, is high with 25mA.
Power consumption is less than 2 mA in 5V operating condition.
34. 34
4.5.2 Salient Features
1. Speed :
When operated at its maximum clock rate a PIC executes most of its instructions in
0.2 s or five instructions per microsecond.
2. Instruction set Simplicity :
The instruction set is so simple that it consists of only just 35 instructions
3. Integration of operational features:
Power-on-reset (POR) and brown-out protection ensure that the chip operates only
when the supply voltage is within specifications. A watch dog timer resets the PIC if the chip
malfunctions or deviates from its normal operation at any time.
1. Programmable timer options:
Three timers can characterize inputs, control outputs and provide internal timing for
the program execution.
2. Interrupt control:
Up to 12 independent interrupt sources can control when the CPU deal with each
sources.
3. Powerful output pin control:
A single instruction can select and drive a single output pin high or low in its 0.2 s
instruction execution time. The PIC can drive a load of up to 25A.
4. I/O port expansion:
With the help of built in serial peripheral interface the number of I/O ports can be
expanded. EPROM/DIP/ROM options are provided.
High performance RISC CPU
Operating speed: DC – 20 MHz clock input DC – 200 ns instruction cycle
Eight level deep hardware stack
Direct, indirect and relative addressing modes
Power-up Timer (PWRT) and Oscillator Start-up Timer (OST)
Three Timers Timer0, Timer 1 and Timer 2.
Watchdog Timer (WDT) with its own on-chip RC oscillator for reliable operation
Programmable code-protection
Power saving SLEEP mode
35. 35
10-bit multi-channel Analog-to-Digital converter
Selectable oscillator options
One USART /SCI port with 9-bit address detection.
Low-power, high-speed CMOS EPROM/ROM technology
Fully static design
Wide operating voltage range: 2.5V to 6.0V
Commercial, Industrial and Extended temperature ranges
Low-power consumption: <2mA @5V, 4MHz, 15 A typical @ 3V, 32 kHz, <1 A
typical standby current
4.5.3 Architecture
The PIC16FXX is a family of low-cost, high-performance, CMOS, fully-static, 8-bit
microcontrollers. All PIC microcontrollers employ an advanced RISC architecture. The
PIC16FXX microcontroller family has enhanced core features, eight-level deep stack, and
multiple internal and external interrupt sources. The two-stage instruction pipeline allows all
instructions to execute in a single cycle, except for program branches (which require two
cycles). A total of 35 instructions (reduced instruction set) are available. Also, a large register
set helps to achieve a very high performance.
The PIC 16FXX uses Harvard architecture, in which, program and data are accessed
from separate memories using separate buses. This improves bandwidth over traditional Von
Neumann architecture where program and data may be fetched from the same memory using
the same bus. Separating program and data buses further allows instructions to be sized
differently than 8-bit wide data words. Instruction opcodes are 14-bits wide making it
possible to have all single word instructions. A 14-bit wide program memory access bus
fetches a 14-bit instruction in a single cycle. A two-stage pipeline overlaps fetch and
execution of instructions. Consequently, all instructions execute in a single cycle (200 ns@
20MHz) except for program branches. The PIC 16F87X devices have a 13-bit program
counter capable of addressing an 8KX14 program memory space. The PIC 16FF876/877
devices have 8Kx 14 words of Flash program memory .The RESET vector is at 0000h and
the Interrupt vector is at 0004h.
36. 36
Memory organization:
The memory module of the PIC microcontroller has two memory blocks.
a) Program memory
b) Data memory
a. Program Memory:
The PIC 16F8XX has 4k x14 program memory space (0000H-0FFFH).It has a 13 bit
Program counter(PC) to access any address (213
=4k). This PIC family uses 13-bit program
counter allowing the controllers to an 8k-program memory without changing the CPU
structure. Two addresses in the program memory address space are treated in a special way
by the CPU. The first address H‘ 000‘ being a go to mainline instruction the second special
address, H‘ 004‘ being a ‗go to in service‘ instruction can be assigned to this address to make
the CPU to jump to the beginning of the Interrupt Service routine located elsewhere in the
memory space.
Figure 4.19
37. 37
b. DATA MEMORY
The data memory of PIC 16F8XX is partitioned into multiple banks which contain the
general purpose registers and the Special function Registers.(SFRs).The bits RP1 and RP0
bits of the status register are used to select these banks. Each bank extends upto 7FH (128
Bytes).The lower bytes of the each bank are reserved for the Special Function Registers.
Above the SFRs are general purpose registers implemented as static RAM.
REGISTER FILE STRUCTURE
In PIC Microcontrollers the Register File consists of two parts namely
a) General Purpose Register File
b) Special Purpose Register File
a) General Purpose Register File:
The general purpose register file is another name for the microcontroller‘s RAM. Data can be
written to each 8-bit location updated and retrieved any number of times.
b) Special Purpose Register File:
The special function register file consists of input, output ports and control registers
used to configure each 8-bit port either as input or output. It contains registers that provide
the data input and data output to a chip resources like Timers, Serial Ports and Analog to
Digital converter and also the registers that contains control bits for selecting the mode of
operation and also enabling or disabling its operation.
39. 39
4.5.4 Addressing Modes
The PIC microcontrollers support only TWO addressing modes .They are
(i) Direct Addressing Mode
(ii) Indirect Addressing mode
Direct Addressing Mode:
In direct addressing mode 7 bits (0-6) of the instruction identify the register file
address and the 8th
bit of the register file address register bank select bit (RP0).
Figure 4.21
The above diagram explains the method of accessing register file address 13H by direct
addressing method.
40. 40
Indirect Addressing Mode
In the indirect addressing mode the 8-bit register file address is first written into a
Special Function Register (SFR) which acts as a pointer to any address location in the register
file A subsequent direct access of INDF will actually access the register file using the content
of FSR as a pointer to the desired location of the operand.
4.5.5 Microcontroller features:
High-Performance RISC CPU.
Only 35 instructions to learn.
Operating speed.
Interrupt capability.
8-level deep hardware stack.
Direct, Indirect and Relative Addressing modes.
Special Microcontroller Features.
Precision Internal Oscillator.
Power-Saving Sleep mode.
Wide operating voltage range (2.0V-5.5V).
Industrial and Extended Temperature range.
Power-on Reset (POR).
Power-up Timer (PWRT) and Oscillator Start-up Timer (OST) .
Brown-out Reset (BOR) with software control option.
Enhanced low-current Watchdog Timer (WDT) with on-chip oscillator (software
selectable nominal 268 seconds with full prescaler) with software enable.
Multiplexed Master Clear with pull-up/input pin.
Programmable code protection.
High Endurance Flash/EEPROM cell.
Program memory Read/Write during run time.
In-Circuit Debugger (on board).
Low-Power Features.
Standby Current.
Operating Current.
Watchdog Timer Current.
41. 41
Peripheral Features.
24/35 I/O pins with individual direction control.
Analog Comparator module with.
Timer0: 8-bit timer/counter with 8-bit programmable prescaler.
Enhanced Timer1.
Timer2: 8-bit timer/counter with 8-bit period register, prescaler and postscaler.
Supports RS-485, RS-232, and LIN 2.0
Auto-Baud Detect
Auto-Wake-Up on Start bit
In-Circuit Serial Programming.
Enhanced Capture, Compare, PWM+ module.
Capture, Compare, PWM module.
Enhanced USART module.
In-Circuit Serial Programming TM (ICSPTM) via two pins.
Master Synchronous Serial Port (MSSP) module supporting 3-wire SPI (all 4
modes) and I2C™ Master and Slave Modes with I2C address mask.
44. 44
4.6 Analog to digital converters:
4.6.1 Introduction:
When configuring and using the ADC the following functions must be considered.
• Channel selection
• ADC voltage reference selection
• ADC conversion clock source
• Interrupt control
• Results formatting
The ADC can be used to convert both analog and digital signals. When converting
analog signals, the I/O pin should be configured for analog by setting the associated TRIS
and ANSEL bits. See the corresponding Port section for more information. Electronic
integrated circuit which transforms a signal from analog (continuous) to digital (discrete)
form. Analog signals are directly measurable quantities. Digital signals only have two states.
For digital computer, we refer to binary states, 0 and 1. Microprocessors can only perform
complex processing on digitized signals. When signals are in digital form they are less
susceptible to the deleterious effects of additive noise. ADC Provides a link between the
analog world of transducers and the digital world of signal processing and data handling.
4.6.2 Application of ADC:
ADC are used virtually everywhere where an analog signal has to be processed,
stored, or transported in digital form.
Some examples of ADC usage are digital volt meters, cell phone, thermocouples,
and digital oscilloscope.
Microcontrollers commonly used 8, 10, 12, or 16 bit ADCs, our micro controller
uses an 8 or 10 bit ADC.
46. 46
CHAPTER-5
SOFTWARE REQUIREMENTS
5.1 Matlab:
5.1.1 Introduction:
MATLAB is a high-performance language for technical computing. It integrates
computation, visualization, and programming in an easy-to-use environment where problems
and solutions are expressed in familiar mathematical notation. Typical uses include
Math and computation
Algorithm development
Data acquisition
Modeling, simulation, and prototyping
Data analysis, exploration, and visualization
Scientific and engineering graphics
Application development, including graphical user interface building
MATLAB is an interactive system whose basic data element is an array that does not
require dimensioning. This allows you to solve many technical computing problems,
especially those with matrix and vector formulations, in a fraction of the time it would take to
write a program in a scalar non interactive language such as C or FORTRAN.
The name MATLAB stands for matrix laboratory. MATLAB was originally written
to provide easy access to matrix software developed by the LINPACK and EISPACK
projects. Today, MATLAB engines incorporate the LAPACK and BLAS libraries,
embedding the state of the art in software for matrix computation.
MATLAB is a high-level language and interactive environment that enables to
perform computationally intensive tasks faster than with traditional programming languages
such as C, C++, and FORTRAN.
MATLAB has evolved over a period of years with input from many users. In
university environments, it is the standard instructional tool for introductory and advanced
courses in mathematics, engineering, and science. In industry, MATLAB is the tool of choice
for high-productivity research, development, and analysis. MATLAB features a family of
add-on application-specific solutions called toolboxes .Very important to most users of
MATLAB, toolboxes allow you to learn and apply specialized technology. Toolboxes are
comprehensive collections of MATLAB functions (M-files) that extend the MATLAB
environment to solve particular classes of problems.
47. 47
Areas in which toolboxes are available include signal processing, control systems,
neural networks, fuzzy logic, wavelets, simulation, aerospace, bioinformatics, image
processing and many others. Areas in which block sets are available include aerospace,
communications, RF, signal processing, video and image processing.
5.1.2 Key features:
High-level language for technical computing
Development environment for managing code, files, and data
Interactive tools for iterative exploration, design, and problem solving
Mathematical functions for linear algebra, statistics, Fourier analysis, filtering,
optimization, and numerical integration
2-D and 3-D graphics functions for visualizing data
Tools for building custom graphical user interfaces
Functions for integrating MATLAB based algorithms with external applications
and languages, such as C, C++, FORTRAN, Java, COM, and Microsoft Excel.
5.2 Simulink Model:
5.2.1 Introduction:
Simulink is an environment for multidomain simulation and Model-Based Design for
dynamic and embedded systems. It provides an interactive graphical environment and a
customizable set of block libraries that let you design, simulate, implement, and test a variety
of time-varying systems, including communications, controls, signal processing, video
processing, and image processing .Add-on products extend Simulink software to multiple
modeling domains, as well as provide tools for design, implementation, and verification and
validation tasks. Simulink is integrated with MATLAB, providing immediate access to an
extensive range of tools that let you develop algorithms, analyze and visualize simulations,
create batch processing scripts, customize the modeling environment, and define signal,
parameter, and test data.
48. 48
5.2.2 Key features:
Extensive and expandable libraries of predefined blocks
Interactive graphical editor for assembling and managing intuitive block diagrams
3.Ability to manage complex designs by segmenting models into hierarchies of
design components
Model Explorer to navigate, create, configure, and search all signals, parameters,
properties, and generated code associated with your model
Application programming interfaces (APIs) that connect with other simulation
programs and incorporate hand-written code .Embedded MATLAB Function blocks for
bringing MATLAB algorithms into Simulink and embedded system implementations.
Simulation modes (Normal, Accelerator, and Rapid Accelerator) for running simulations
interpretively or at compiled C-code speeds using fixed- or variable-step solvers Graphical
debugger and profiler to examine simulation results and then diagnose performance and
unexpected behavior in your design Full access to MATLAB for analyzing and visualizing
results, customizing the modeling environment, and defining signal, parameter, and test data.
Model analysis and diagnostics tools to ensure model consistency and identify modeling
errors.
Fig 5.1 Simulink model
49. 49
5.2.3 CREATING AND WORKING WITH MODELS
With Simulink, we can quickly create, model, and maintain a detailed block diagram of your
system using a comprehensive set of predefined blocks. Simulink provides tools for
hierarchical modeling, data management, and subsystem customization, making it easy to
create concise, accurate representations, regardless of your system's complexity.
Selecting and Customizing Blocks
Simulink software includes an extensive library of functions commonly used in
modeling a system. These include:
Continuous and discrete dynamics blocks, such as Integration and Unit Delay
Algorithmic blocks, such as Sum, Product, and Lookup Table
Structural blocks, such as Mux, Switch, and Bus Selector
We can customize these built-in blocks or create new ones directly in Simulink and
place them into your own libraries. Additional block sets (available separately) extend
Simulink with specific functionality for aerospace, communications, radio frequency, signal
processing, video and image processing, and other applications .We can model Physical
system in Simulink. Simscape, SimDriveline, SimHydraulics, SimMechanics and
SimPowerSystem (all available separately) provide expanded capabilities for
modeling physical systems, such as those with mechanical, electrical, and hydraulic
components.
Incorporating MATLAB Algorithms and Hand-Written Code
When we incorporate MATLAB code, you can call MATLAB functions for data
analysis and visualization. Additionally, Simulink lets you use Embedded MATLAB code to
design embedded algorithms that can then be deployed through code generation with the rest
of your model. We can also incorporate hand-written C, FORTRAN, and Ada code directly
into a model, enabling you to create custom blocks in your model.
50. 50
5.2.4 BUILDING AND EDITING A MODEL
With Simulink, we build models by dragging and dropping blocks from the library
browser onto the graphical editor and connecting them with lines that establish mathematical
relationships between the blocks. We can arrange the model by using graphical editing
functions, such as copy, paste, undo, align, distribute, and resize.
Fig 5.2 Building a Model
The Simulink user interface gives you complete control over what you can see and
use onscreen. You can add your commands and submenus to the editor and context menus.
We can also disable and hide menus, menu items, and dialog box controls.
5.3 SIMULATION RESULTS:
5.3.1 Existing Simulink Model:
Existing System
Fig 5.3
59. 59
CHAPTER-6
FUTURE SCOPE
6.1 Advantages:
To achieve the high efficiency and high power density by using Phase shift
controlled ABR (Active Boost Rectifier).
Soft switching is implemented in this system.
It will be reduce the switching stress and losses.
To achieve good voltage regulation.
To achieve high efficiency.
It will increase the output power.
It can achieve a much higher voltage gain and low output voltage ripple.
The main switches can be turned ON at ZCS so that the main switching losses are
reduced.
The current falling rates of the diodes are controlled by the leakage inductance so
that the diode reverse-recovery problem is alleviated.
The primary windings of two coupled inductors are connected in parallel to share the
input current and reduce the current ripple at the input.
The input current can be automatically shared by each phase and low ripple currents
are obtained at input.
6.2 Applications:
It is primarily utilized for data acquisition by computerized devices.
In Photovoltaic Energy Conversion Systems
In High-Intensity Discharge Lamp (HID)
In Dc Back-Up Energy Systems
In Fuel Cell Energy System
In Electric Vehicles to increase in power & efficiency.
In Lamp Ballasts For Automobile Headlamps
60. 60
6.3 Future scope:
This project having good future response because of its soft-switching property. It
can be used for both dc as well as ac systems. It can be used in electric vehicle to increase the
power & efficiency. Because of limited fuels i.e. petrol, diesel etc. this electric vehicle will be
used more. So this project have good future work. Despite of this, this project can be
implemented for different energy conversion systems. It is also used for back-up energy
systems for later use. It reduces the stress losses and harmonics so it can be used for different
industrial purposes. So it will increase the output power value and efficiency which will give
more profit by investing less money. It is primarily used for data acquisition in computerized
devices so it has also future in IT industries to reduce losses and harmonics.
61. 61
CHAPTER-7
CONCLUSION
7.1 Conclusion:
In this paper, a family of soft-switching dc–dc converters has been presented for
high-efficiency applications based on the novel proposed ABRs. In the proposed converters,
all the power switches are operated at fixed 50% duty cycle, and the output voltage regulation
is achieved by adopting phase shift control between the primary and secondary-side switches.
ZVS performance has been achieved for both the primary- and secondary-side switches in a
wide voltage and load range. Furthermore, the reverse-recovery problems associated with the
rectifier diodes are alleviated. Therefore, the switching losses of the proposed converters can
be reduced, which is important for high-frequency, high-efficiency, and high-power density
applications. Moreover, the leakage inductance of the transformer has been utilized as the
energy transfer inductor, and all the devices voltages are clamped to the input or output
voltage. Thus, the voltage overshoots on the devices are effectively suppressed. In addition,
the proposed converters are suitable for wide-range applications because they can operate
either in Buck or Boost mode.
As an example, the FBC with VD ABR is analyzed with operation principles and
output characteristics presented. Experimental results of a 1 kW prototype have verified the
feasibility and effectiveness of the proposed topological methodology and converters.
62. 62
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