investigation of a diode-capacitor assisted single-phase power factor corrected boost-buck ac-dc ...

181 Pages·2017·3.32 MB·English

INVESTIGATION OF A DIODE-CAPACITOR
ASSISTED SINGLE-PHASE POWER FACTOR
CORRECTED BOOST-BUCK AC-DC CONVERTER

A Thesis
Presented to the
Department of Electrical and Electronic Engineering

In Partial Fulfillment of the Requirements for the Degree
Master of Science in Electrical and Electronic Engineering
By
Md. Jannatul Ferdous

Bangladesh University of Engineering and Technology (BUET)
Dhaka, Bangladesh
January, 2017
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ACKNOWLEDGEMENTS

All praise be to Allah and I thank Allah for enlightening my way and directing me
through each and every success I have or may reach.
I would like to express my sincere gratitude and deep appreciation to my supervisor,
Professor Dr. Mohammad Jahangir Alam for his guidance, encouragement and
assistance in the process of completing this work. I also pay deep reverence to him for his
research motivation and encouragement to me and for having faith on me with my work.
I would like to thank gratefully to Dr. Mohammad Ali Choudhury for his persistent
valuable guidance and suggestions in my thesis work. It is my great fortune to work
under his guidance. My heartfelt thanks to him for his support, belief and patience on me
and many opportunities he has given me over the years.
Finally, I would like to pay my profound gratitude and genuine thanks to my parents, my
wife Umme Salma and my friend Shahriar Kabir for their inspiration towards the
completion of this work.

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ABSTRACT
Single phase active input power factor corrected and input current improved rectifiers use
switching either between the rectifier and the load or between the supply and the rectifier.
Voltage and current feedback control produces the gate pulse necessary for the
improvement of input current total harmonic distortion, high input power factor and
regulated output voltage at acceptably high power conversion efficiency. Usually the
boost switching stage is popular due to its advantage of availability of input inductor
current tracking with input voltage. The ĈUK and SEPIC switching stage having input
boost switching topology may be used where boost-buck voltage/current gain is
necessary. In all the topologies, the ideal voltage gain and conversion efficiency deviates
significantly at very high or at very low duty cycle of the switching signal of the switch.
In DC-DC converter this problem is addressed by pre/post gain or attenuation by flyback
or feed forward high frequency transformer topologies. The same pre/post gain operation
can be achieved by transformerless diode-capacitor-inductor voltage/current
divider/multiplier circuit. In this research similar considerably high efficiency operation
of a boost-buck AC-DC converter is investigated. The input to AC-DC rectifier has boost
topology in the front followed by a capacitor diode voltage divider. AC-DC converters
have additional requirements of input current total harmonic reduction and high input
power factor. The proposed converter is therefore designed and studied for proper
voltage/current feedbacks. The feedbacks also maintain regulated dc output voltage of the
proposed converter. The open loop operation results of the proposed converter are
substantiated by prototype small scale experimental circuit.

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TABLE OF CONTENTS
ACKNOWLEDGEMENTS iv
ABSTRACT v
LIST OF TABLES ix
LIST OF FIGURES x
LIST OF ABBREVIATIONS OF TECHNICAL TERMS xxii

Chapter 1 : INTRODUCTION
1.1 AC -DC Conversion 1
1.2 Background and present status of the problem 1
1.3 Major Challenges of PFC Techniques 2
1.4 Goal of this Thesis 3
1.5 Thesis Organization 3

Chapter 2 : AC-DC CONVERTER AND ITS PROBLEM IN USE
2.1 Introduction 5
2.2 Single phase Half- Wave AC-DC Converter 6
2.3 Single Phase Full Wave AC-DC Converter 7
2.4 Three Phase AC-DC Converter 10
2.5 P r o b l e m a s s o c i a t e d w i t h t h e single-phase AC-DC converter connected 13
in line

Chapter 3 : POWER FACTOR CORRECTION: DIFFERENT APPROACHES
3.1 Passive PFC Approach 20
3.2 Active PFC Approach 23
3.2.1 Buck Converter Based Active PFC 24
3.2.2 Boost Converter Based Active PFC 27
3.2.3 Buck-Boost Converter Based Active PFC 29
3.2.4 SEPIC Converter Based Active PFC 32

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Chapter 4 : DIODE-CAPACITOR ASSISTED BOOST-BUCK AC-DC CONVERTER
FOR PFC
4.1 Proposed Boost- Buck AC-DC Converter-Output Split Capacitor 35
4.2 Principle of Operation 36
4.2.1 Ideal Voltage Gain Expression of Proposed Boost-Buck single- 40
phase AC-DC converter
4.3 Proposed Boost-Buck AC-DC Converter, Output Bridge Rectifier 47
4.3.1 Principle of Operation of Output Bridge Type Proposed Boost 48
Buck Converter
4.3.2 Ideal Input/output Voltage Relationship of Proposed Boost-Buck 50
Output Bridge type AC-DC Converter
4.4 Circuit Parameters 53
4.5 Performance of Proposed Split Capacitor Output Circuit 53
4.5.1 Proposed converter performance at different switching 54
frequencies
4.6 Discussions 81

Chapter 5 : INPUT CURRENT AND POWER FACTOR IMPROVEMENT OF
PROPOSED SINGLE -PHASE AC-DC CONVERTER
5.1 Control Circuit of Proposed AC-DC Converter 82
5.2 Working Procedure 83
5.3 Tuning of PI Control Circuit: 86
5.4 Stable Dynamic Response of Proposed Converter using PI controller 89
5.5 Input Current Shaping by PI controller 92
5.6 Stablity of output voltage in case of source disturbances 98
5.7 Input Power Factor Improved by PI controller 103
5.8 Discussions 106

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Chapter 6 : EXPERIMENTAL RESULTS OF THE PROPOSED SINGLE PHASE
BOOST- BUCK CIRCUIT WITHOUT FEEDBACK CONTROL
6.1 Proposed PFC circuit practical prototype and its typical performance 108
6.2 Comparison between Experimental and Simulated Results 150
6.3 Discussion 153

Chapter 7 : CONCLUSION
7.1 Summary of the Thesis 154
7.2 Future Work 155

References 156

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LIST OF TABLES
Table 2.I : Calculation of Total Harmonic Distortion (THD%) in Pspice 16
Software
Table 4-I(a) : Simulated and theoretical output voltage comparison Table 46
Table 4-I(b) : Simulated and theoretical output voltage comparison Table 52
Table 4-II : Parameters of proposed circuit used for simulation 53
Table 4-III : Comparison Table in terms of THD, Input power factor, 62
Efficiency and Gain for fs = 2 KHz
Table 4-IV : Comparison Table in terms of THD, Input power factor, 66
Efficiency and Gain for fs = 3 KHz
Table 4-V : Comparison Table in terms of THD, Input power factor, 69
Efficiency and Gain for fs = 4 KHz
Table 4-VI : Comparison Table in terms of THD, Input power factor, 72
Efficiency and Gain for fs = 5 KHz
Table 4-VII : Comparison Table in terms of THD, Input power factor, 75
Efficiency and Gain for fs = 6 KHz
Table 4-VIII : Comparison Table in terms of THD, Input power factor, 78
Efficiency and Gain for fs = 7 KHz
Table 5-I : Effect of THD at different boost inductor values with and 97
without control
Table 5-II : Input power factor without control (Buck mode) 103
Table 5-III : Input power factor with PI controller (Buck mode) 104
Table 5-IV : Input power factor without control (Boost mode) 105
Table 5-V : Input power factor with PI controller (Boost mode) 105
Table 6-I : List of components and their corresponding values for 108
practical circuit
Table 6-II : List of figures and their names 109
Table 6-III : Comparison Table between experimental and simulated data 150

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