i
HIGH EFFICIENCY AND HIGH GAIN NON-ISOLATED
BIDIRECTIONAL DC-DC CONVERTER WITH SOFT SWITCHING
CAPABILITY
RATIL HASNAT ASHIQUE
A thesis submitted in fulfilment of the
requirements for the award of the degree of
Doctor of Philosophy
Faculty of Electrical Engineering
Universiti Teknologi Malaysia
MAY 2018
iii
DEDICATION
To my beloved parents and my wife,
for their endless love, motivation and support.
iv
ACKNOWLEDGEMENT
All praise is due to Allah (SWT), who granted me the ability to complete this
research. Thereby, I am much indebted to His mercy and blessings that he bestowed
upon me.
Next, I would like to express my heartiest gratitude to my project supervisor,
Prof. Dr. Zainal Salam for his perpetual guidance, scholarly assistance and
motivational support throughout this research.
I also sincerely thank all the lecturers from whom I learned a lot. Not to
mention, thanks to my fellow postgraduate friends for sharing useful ideas,
information, and moral support during this study.
Last but not the least I would like to express my sincere appreciation and
gratitude to my parents for their continuous encouragements and especially my wife
who endured all the difficulties during my studies happily.
v
ABSTRACT
The non-isolated dc-dc power converters are considered as a unique option
for flexible voltage control and adaptation in the modern energy conversion systems
due to their simple and light configurations. To this date, these converters are
primarily investigated to generate high efficiency and high gain with a sustained soft
switching capability and a smaller footprint. On that account, this work proposes
two effective solutions to address the aforementioned issues. First, a high-efficiency
soft switching non-isolated bidirectional dc-dc converter with a simple configuration
is proposed. The converter executes the zero voltage zero current switching
(ZVZCS) over a wide operating region to ensure high efficiency. For verification, a
150 W experimental prototype is built and tested for soft switching performance by
varying the input voltage, switching frequency and the loading. It is observed that
the efficiency remains consistently high and has a full-load maximum of 98.2% in
the boost mode and 97.5% in the buck mode. The analysis of the Electromagnetic
Interference (EMI) performance of the converter also shows the improvement in the
noise signature. Second, an improved high gain zero voltage switching (ZVS) non-
isolated bidirectional dc-dc converter is proposed. The high gain is realized by using
an intermediate energy storage cell with reduced size. Besides, the ZVS is
implemented by two integrated auxiliary resonant networks. These networks ensure
sustained ZVS operation over the entire duty ratio. A 200 W prototype is built to
verify the concept. As a result, a full load efficiency of 97.5% (in boost mode) and
95.5% (in buck mode) is recorded at fs= 30 kHz. Also, these efficiencies are
recorded as 97% (boost mode) and 94.5% (buck mode) at fs= 100 kHz. Moreover, it
is observed that the efficiency (and so the soft switching) is consistent over the entire
gain profile. However, there is a slight additional drop of 1.5% (boost mode) and 1%
(buck mode) at extreme duty ratios. Both converters also implement soft switching
for auxiliary switches and eliminate the reverse recovery loss.
vi
ABSTRAK
Penukar kuasa dc-dc tidak terasing dianggap sebagai pilihan unik untuk
pengawal voltan yang fleksibel dan penyesuaian dalam sistem penukaran tenaga
moden disebabkan konfigurasinya yang mudah dan ringan. Sehingga kini, penukar
ini menjadi keutamaan untuk menjana kecekapan tinggi dan gandaan voltan tinggi
dengan keupayaan beralih lembut yang berterusan dan tapak yang lebih kecil.
Sehubungan itu, kerja ini mencadangkan penyelesaian yang berkesan untuk
menangani isu tersebut. Pertama, penukar dc-dc pensuisan lembut tidak terasing
dwiarah berkecekapan tinggi dengan konfigurasi mudah dicadangkan. Penukar
melaksanakan mod pensuisan voltan sifar dan arus sifar (ZVZCS) untuk memberikan
kecekapan tinggi dalam julat operasi yang luas. Untuk pengesahan, prototaip
eksperimen 150 W dibina dan diuji untuk prestasi pensuisan lembut dengan
mengubah voltan masukan, frekuensi pensuisan dan bebanan. Diperhatikan bahawa
kecekapan secara konsisten tinggi dan mempunyai kecekapan beban penuh 98.2%
dalam mod boost dan 97.5% dalam mod buck. Analisis prestasi gangguan
elektromagnetik (EMI) penukar jelas menunjukkan penambahbaikan terhadap
pengurangan hingar. Kedua, penambahbaikan penukar dc-dc gandaan tinggi
pensuisan voltan sifar (ZVS) tidak terasing dwiarah dicadangkan. Pensuisan lembut
dilakukan oleh dua rangkaian bersepadu resonan pembantu. Ciri penting bagi
penukar ini adalah ZVS dapat dikekalkan dalam keseluruhan kitar tugas (nisbah
gandaan). Ini memastikan gandaan voltan tinggi dengan kecekapan operasi yang
tinggi. Prototaip 200 W diuji untuk mengesahkan operasi penukar. Hasilnya,
kecekapan beban penuh 97.5% (dalam mod boost) dan 95.5% (dalam mod buck)
dicatatkan pada fs = 30 kHz. Begitu juga, kecekapan adalah 97% (mod boost) dan
94.5% (mod buck) pada fs = 100 kHz. Tambahan lagi, diperhatikan bahawa
kecekapan (dan pensuisan lembut) konsisten di seluruh kawasan operasi. Walau
bagaimanapun sedikit penurunan sebanyak 1.5% (mod boost) dan 1% (mod buck)
pada nisbah kitaran tugas yang melampau. Kedua-dua penukar memastikan
pensuisan lembut bagi suis-suis pembantu dan menghapuskan kehilangan pemulihan
terbalik.
vii
TABLE OF CONTENTS
CHAPTER TITLE PAGE
DECLARATION ii
DEDICATION iii
ACKNOWLEDGEMENT iv
ABSTRACT v
ABSTRAK vi
TABLE OF CONTENTS vii
LIST OF TABLES xiv
LIST OF FIGURES xv
LIST OF ABBREVIATIONS xx
LIST OF SYMBOLS xxi
LIST OF APPENDICES xxiii
1 INTRODUCTION 1
1.1 Application Overview of the dc-dc Converter 1
1.2 Challenges for High-Performance dc-dc
Converter Operation 3
1.3 Problem Statements 4
1.4 Objectives of Research 5
1.5 Scope of Research 6
1.6 Organization of Thesis 7
2 LITERATURE REVIEW 9
2.1 Introduction 9
viii
2.2 A Review of the Soft Switching Techniques 11
2.2.1 The Zero Voltage Switching (ZVS) 12
2.2.2 The Zero Current Switching (ZCS) 14
2.2.3 The Zero Voltage Zero Current
Switching (ZVZCS) 16
2.2.4 The True Zero Voltage Zero Current
Switching (true ZVZCS) 16
2.3 A Review of Soft Switching Non-isolated dc-
dc Converters 18
2.3.1 The Snubber Based Converters 21
2.3.1.1 The Simple Lossless Snubber
Based Converter 21
2.3.1.2 The Active Snubber Based
Converter 21
2.3.1.3 The Passive Snubber Based
Converter 22
2.3.2 The Series Resonant Network Based
Converter 24
2.3.3 The Shunt Resonant Network Based
Converter 24
2.3.3.1 The Switched Capacitor
Resonant Converter 25
2.3.3.2 The Switched Inductor Shunt
Resonant Converter 26
2.3.3.3 The Coupled Inductor Shunt
Resonant Converter 27
2.3.3.4 The Compound Shunt
Resonant Converter 27
2.3.4 The Pulse Frequency Modulated
(PFM) Converter 29
2.3.4.1 The PFM Resonant Converter 29
2.3.4.2 The Active Edge Resonant
(AER) Converter 30
ix
2.4 General Comments on the Soft Switching
Converters 31
2.4.1 The Snubber Converters 32
2.4.2 The Series Resonant Converters 32
2.4.3 The Shunt Resonant Converters 33
2.4.4 The Pulse Frequency Modulated
(PFM) Converters 34
2.5 A Comparative Evaluation of the Soft
Switching Converters 34
2.5.1 Component Count 35
2.5.2 The Output Voltage and Current
Ripple 36
2.5.3 The Soft Switching Techniques 37
2.5.4 The Soft Switching Range 38
2.5.5 The Power Consumption 39
2.6 Summary 42
3 HIGH EFFICIENCY NON-ISOLATED
BIDIRECTIONAL DC-DC CONVERTER
FAMILY WITH SOFT SWITCHING
OPERATION 44
3.1 Introduction 44
3.2 The Efficiency Improvement with Associated
Drawbacks in the Earlier Designs 46
3.3 The Proposed Converter: Configuration and
Operation 49
3.3.1 Boost Mode Operation 50
3.3.1.1 Interval 1 [t0-t1] 51
3.3.1.2 Interval 2 [t1-t2] 52
3.3.1.3 Interval 3[t2-t3] 53
3.3.1.4 Interval 4 [t3-t4] 54
3.3.1.5 Interval 5 [t4-t5] 55
3.3.1.6 Interval 6 [t5-t6] 56
3.3.1.7 Interval 7 [t6-t7] 56
3.3.1.8 Interval 8 [t7-t8] 57
x
3.3.2 Buck Mode Operation 58
3.3.2.1 Interval 1 [t0-t1] 59
3.3.2.2 Interval 2 [t1-t2] 60
3.3.2.3 Interval 3 [t2-t3] 61
3.3.2.4 Interval 4 [t3-t4] 63
3.3.2.5 Interval 5 [t4-t5] 63
3.4 Design of the Circuit Parameters 64
3.4.1 Design of Lr1 and Lr2 65
3.4.2 Design of Cr1 66
3.4.3 Design of Lr3 67
3.4.4 Output Capacitors and Main Inductor
Selection 68
3.5 Experimental Verification 69
3.5.1 The DSP TMS320f2812 69
3.5.2 The DC Electronic Load 69
3.5.3 The Experimental Setup 70
3.5.4 The Closed Loop Digital Controller 72
3.5.5 Results and Discussion on Soft
Switching Performance 77
3.5.6 EMI Characterization 85
3.5.7 Other ZVZCS Topologies 90
3.6 Summary 91
4 SOFT SWITCHING NON-ISOLATED
BIDIRECTIONAL DC-DC CONVERTER
WITH HIGH GAINCAPABILITY 92
4.1 Introduction 92
4.2 The Gain Boosting Techniques in Non-
isolated dc-dc Converters 94
4.2.1 The Multilevel High Gain Non-
isolated dc-dc Converters 94
4.2.2 The Coupled Inductor Based High
Gain Non-isolated dc-dc Converters 95
4.2.3 The Switched Capacitor Based High
Gain Non-isolated dc-dc Converters 95
xi
4.2.4 Other Hybrid High Gain Topologies 96
4.3 The Proposed Converter: Configuration and
Operation 97
4.3.1 Boost mode 99
4.3.1.1 Interval 1[(t0-t1), resonance
mode] 101
4.3.1.2 Interval 2 [(t1-t2), inductor
charging mode] 102
4.3.1.3 Interval 3 [(t2-t3), capacitor
charging and resonance mode] 103
4.3.1.4 Interval 4 [(t3-t4), dead time
mode] 104
4.3.1.5 Interval 5 [(t4-t5), inductor and
capacitor discharging mode] 104
4.3.1.6 Interval 6 [(t5-t6), dead time
mode] 105
4.3.2 Buck Mode 106
4.3.2.1 Interval 1[(t0-t1), inductor
charging and resonance mode] 107
4.3.2.2 Interval 2 [(t1-t2), inductor
charging and output capacitor
discharging mode] 107
4.3.2.3 Interval 3 [(t2-t3), resonance
mode] 108
4.3.2.4 Interval 4 [(t3-t4), inductor
discharging mode] 109
4.3.2.5 Interval 5 [(t4-t5), dead time
mode] 110
4.4 Voltage Conversion Ratios 110
4.4.1 The Voltage-Second (vol-sec) Balance
in the Switching Converters 111
4.4.2 Boost Mode 111
4.4.2.1 Derivation of the Voltage-
Second Balance Equations 112
xii
4.4.2.2 Graphical Presentation of the
Step-Up Ratio and
Comparison with Similar
Converters 114
4.4.3 Buck Mode 115
4.4.3.1 Derivation of the Voltage-
Second Balance Equations 115
4.4.3.2 Graphical Presentation of the
Step-Down Ratio and
Comparison with Similar
Converters 117
4.5 Designing the Circuit Parameters 117
4.5.1 Optimization of Resonant Capacitors
(Cr1 and Cr2) 118
4.5.2 Selection of filter capacitors, CL, CH1
and CH2 121
4.5.3 Selection of energy storage capacitor,
C1 122
4.5.4 Determining the Value of Resonant
Inductors, Lr1andLr2 123
4.5.5 Selection of the Main Inductor, LM 123
4.5.6 Selection of Auxiliary
Inductors,La1and La2 124
4.6 Experimental Verification 126
4.6.1 The DSP TMS320f2812 126
4.6.2 The DC Electronic Load 127
4.6.3 The Closed Loop Digital Controller 127
4.6.4 Experimental Setup 129
4.6.5 Results and Discussion 131
4.6.5.1 Voltage Gain 131
4.6.5.2 Inductor Current and
Capacitor Voltages 132
4.6.5.3 Soft Switching Operation 133
4.6.5.4 Efficiency 136
xiii
4.7 Summary 142
5 SUMMARY, CONCLUSION AND FUTURE
WORK 143
5.1 Summary of Work 143
5.2 Suggestions for Future Work 145
REFERENCES 147
APPENDIX A 158
xiv
LIST OF TABLES
TABLE NO. TITLE PAGE
2.1 The classification of the soft switching 20
2.2 Overview of the converter performances 41
3.1 Circuit parameters and their values 71
3.2 The performance parameters 76
3.3 Value of auxiliary inductors with frequency applied 82
4.1 PID controller and the performance parameters 128
4.2 Specifications for experimental test 129
4.3 Switch and diode ratings
131
4.4 Efficiency measurement at different operating points
in the boost and buck modes
137
4.5 Main features of the proposed converter and its
comparison to relevant high gain topologies reported
in the literature
141
xv
LIST OF FIGURES
FIGURE NO. TITLE PAGE
2.1 The hard switching (HS) crossover (a) at the turn on
(simulation) (b) at the turn on and turn off
(linearized)
12
2.2 The zero-voltage switching crossover (a) at the turn
on (simulation) and (b) at turn on and turn off
(linearized)
13
2.3 The exemplary ZVS execution at the main switch
(S1) of a boost converter (auxiliary circuit omitted)
14
2.4 The zero-current switching crossover (a) at the turn
on (simulation) and (b) at the turn on and turn off
(linearization)
15
2.5 Exemplary circuits to achieve the ZCS by applying a
current restricting inductor or current diversion
circuit in a boost converter
15
2.6 The zero-voltage zero-current crossover at the turn on
and turn off
16
2.7 The true zero-voltage zero-current crossover (a) at
turn on (simulated) (b) at turn on and turn off
(linearized)
17
2.8 The exemplary true ZVZCS execution in a boost
converter (the auxiliary circuit is omitted)
18
2.9 The classification of the soft switching converters 19
2.10 Active snubber network (the grey area) based
22
xvi
converters (a) [52], (b) [66], (c) [72]
2.11 Passive snubber network (the grey area) based
converters (a) [39], (b) [60], (c) [47], (d) [44]
23
2.12 The switched capacitor network (the grey area) based
converters (a), (b), (c) [49]
25
2.13 The switched inductor network (grey area) based
converters (a) [74], (b), (c) [41], (d) [55]
26
2.14 The coupled inductor network (grey area) based
converters (a) [73], (b) [50]
27
2.15 The compound shunt resonant network (grey area)
based converters (a) [32], (b) [67], (c) [63]
28
2.16 The pulse frequency modulated network (grey area)
based converters (a) [68], (b) [36], (c) [33], (d) [35]
30
2.17 AER network (grey area) based converters (a) [45],
(b) [46], (c) [59], (d) [49], (e) [52]
31
2.18 Average number of active and passive components in
soft switching converters
35
2.19 The output (a) voltage and (b) current ripple in soft
switching converters
37
2.20 Average switching loss in the main switches of the
soft switching converters
38
2.21 (a) Average loss in percentage share and (b) average
efficiency in the soft switching converters
41
3.1 The proposed ZVZCS bidirectional converter 50
3.2 The PWM switching and theoretical waveforms in
boost mode
51
3.3 Boost operational interval 1(t0- t1) 52
3.4 Boost operational interval 2 (t1- t2) 53
3.5 Boost operational interval 3 (t2- t3) 54
3.6 Boost operational interval 4 (t3- t4) 55
3.7 Boost operational interval 5 (t4- t5) 55
xvii
3.8 Boost operational interval 6 (t5- t6) 56
3.9 Boost operational interval 7 (t6- t7) 57
3.10 Boost operational interval 8 (t7- t8) 58
3.11 The PWM switching and theoretical waveforms in
buck mode
59
3.12 Buck operational Interval 1 (t0-t1) 60
3.13 Buck operational Interval 2 (t1-t2) 61
3.14 Buck operational Interval 3 (t2-t3) 62
3.15 Buck operational Interval 4 (t3-t4) 63
3.16 Buck operational Interval 5 (t4-t5) 64
3.17 Experimental setup for testing the prototype
converter
70
3.18 Block diagram of the closed loop system
73
3.19 Schematic block diagram of the closed loop
controller embedded in the DSP TMS320f2812
75
3.20 The output voltage response of the converter to the
load variations in the (a) boost (b) buck mode
76
3.21 Soft transition of (a) S1 (b) S2 in boost mode; (c) S1
(b) S2 in buck mode
78
3.22 Soft transition of (a) Sr1 (b) Sr2 in boost mode; (c) Sr1
(d) Sr2 in buck mode
80
3.23 The efficiency of the proposed converter (a) in boost
mode against hard switching boost and the converters
in [32, 76] (b) in buck mode against hard switching
buck and the converter in [67] at fs= 100 kHz and
VL= 50 V.
81
3.24 Efficiency in boost mode (a) against fs at VL=50 V (b)
against VL at fs=100 kHz
83
3.25 Efficiency in buck mode (a) against fs at VL=50 V (b)
against VL at fs=100 kHz
84
xviii
3.26 The soft switching map for the proposed converter
85
3.27 Boost mode noise level of (a) iH (b) iS1 in the hard
switching and the proposed ZVZCS soft switching
condition
88
3.28 Buck mode noise level of (a) iL (b) iS1 in the hard
switching and the proposed ZVZCS soft switching
condition
89
3.29 Other ZVZCS topologies (a) buck/boost (b) Cuk (c)
SEPIC
90
4.1 The proposed high gain bidirectional converter with
the energy storage cell and two identical auxiliary
networks (AN1 and AN2)
98
4.2 The auxiliary resonant networks (AN1 and AN2) in
the proposed high gain bidirectional converter
99
4.3 PWM switching and theoretical voltage current
waveforms in the boost mode
100
4.4 Boost operational interval 1 (t1-t0) 102
4.5 Boost operational interval 2 (t1 -t2) 103
4.6 Boost operational interval 3 (t2-t3) 103
4.7 Boost operational interval 4 (t3-t4) 104
4.8 Boost operational interval 5 (t4-t5) 105
4.9 Boost operational interval 6 (t5-t6) 105
4.10 PWM switching and theoretical voltage and current
waveforms in the buck mode
106
4.11 Buck mode operational interval 1 (t0-t1) 107
4.12 Buck mode operational interval 2 (t1-t2) 108
4.13 Buck mode operational interval 3 (t2-t3) 109
4.14 Buck mode operational interval 4 (t3-t4) 109
4.15 Buck mode operational interval 5 (t4-t5) 110
4.16 Step up gain vs. duty cycle ratio (d1) against [93] and
[53]
115
4.17 Step down gain vs. duty cycle ratio (d1) against [93] 117
xix
4.18 Maximum inductance value for LM in CCM mode of
operation
124
4.19 Block diagram of the closed loop system 128
4.20 The output voltage response of the converter to the
load variations in the (a) boost (b) buck mode
129
4.21 Experimental setup for testing the prototype circuit 130
4.22 Voltage waveforms in boost mode at (a) d1=0.6 (b)
d1=0.8; and in buck mode at (c) d1=0.3 (d) d1= 0.6
132
4.23 Current waveform of iLM (a) in boost mode (b) in
buck mode; voltage waveforms of C1 (c) in boost
mode (d) in buck mode; (e) voltage waveforms of
CH1 and CH2 in boost/buck mode
133
4.24 Voltage and current waveforms in boost mode for (a)
S1 (b) S3 (c) S4 (d) S5
134
4.25 Voltage and current waveforms in buck mode for (a)
S1 (b) S2 (c) S4 (d) S5
135
4.26 Voltage and current waveforms in boost mode for (a)
Sr1 (b) Sr2 ;in buck mode for (c) Sr1
136
4.27 Efficiency of the proposed converter against that in
[93] for (a) boost mode and (b) buck mode with and
without auxiliary network (AN)
138
4.28 Measured efficiency against d1 (a) in boost mode; (b)
in buck mode at full load (PO= 200 W)
139
xx
LIST OF ABBREVIATIONS
DSP - Digital Signal Processor
EV - Electric Vehicle
ESU - Energy Storage Unit
HS - Hard Switching
PV - Photovoltaic
PID - Proportional-Integral-Derivative
RE - Renewable Energy
RES - Renewable Energy Sources
ZVS - Zero Voltage Switching
ZCS - Zero Current Switching
ZVZCS - Zero Voltage Zero Current Switching
ZVT - Zero Voltage Transition
ZCT - Zero Current Transition
ZVZCT - Zero Voltage Zero Current Transition
xxi
LIST OF SYMBOLS
C - Capacitor
D - Diode
Gstep-up - Step up gain
Gstep-down - Step down gain
I - Current
iH - High side current
iL - Low side current
iSr1 - Current through switch Sr1
iSr2 - Current through switch Sr2
iS1 - Current through switch S1
iS2 - Current through switch S2
iS3 - Current through switch S3
iS4 - Current through switch S4
iS5 - Current through switch S5
KP - PID controller proportional coefficient
KI - PID controller integral coefficient
KD - PID controller derivative coefficient
L - Inductor
P - Power
RLr1 - Parasitic resistance of inductor Lr1
RLr2 - Parasitic resistance of inductor Lr2
RLr3 - Parasitic resistance of inductor Lr3
V - Voltage
vL - Low side voltage
vH - High side voltage
xxii
vSr1 - Voltage across switch Sr1
vSr2 - Voltage across switch Sr2
vS1 - Voltage across switch S1
vS2 - Voltage across switch S2
vS3 - Voltage across switch S3
vS4 - Voltage across switch S4
vH - High side voltage
vL - Low side voltage
ΔE - Change in efficiency
ΔV - Change in voltage
xxiii
LIST OF APPENDICES
APPENDIX TITLE PAGE
A List of Publications 158
CHAPTER 1
INTRODUCTION
1.1 Application Overview of the dc-dc Converter
The sharp increase in the power requirements for modern computers, mobile
devices, automotive/spacecraft and renewable energy system (RES) demand more
efficient and reliable dc-dc power converters. Notably, as the applications are
becoming more complex and diverse, the demand for high-performance, cost-
effective converter topologies continue to grow. Consequently, there is an impetus
to develop dc-dc converters with higher efficiency, higher gain and a smaller
footprint that can function under flexible operating conditions. From this viewpoint,
the non-isolated dc-dc power converters are considered as a preferable option,
compared to its bulkier and expensive isolated counterparts.
In the communication and computer sector, the power supply can be either an
isolated or non-isolated type of dc-dc converter. Regardless of the type, it is required
to be efficient, inexpensive and lightweight with low ripple noise to protect the
delicate electronics. Besides, it is expected to support a wide range of input voltage,
but should not be limited by certain load constraints. For the renewable energy
system (RES), these converters are primarily used to convert the dc voltage from one
level to another, i.e. from photovoltaic [1], wind [2], fuel cell [3, 4], wave, ocean
2
thermal and thermoelectric systems [5, 6]. In the microgrid environment, it also
provides seamless integration of the RES to the internal grid by allowing the voltage
and current from the RES to be precisely controlled. Additionally, an increasing
number of RES deploy energy storage units (ESU) to store and manage the power
flow more efficiently. The ESU requires non-isolated dc-dc power converters to
interface with, for example, PV arrays or dc loads, such as electric vehicles. Such
application illustrates the necessity of a dc conversion system with bidirectional
power flow capability.
In the automotive industry—one of the main user of dc conversion systems,
the non-isolated dc-dc converter is primarily used for internal electronics and vehicle
control [7]. There is a wide range of dc voltage levels to be derived from the main
battery for various vehicle instrumentation needs. Looking into the future, the
electric vehicle (EV) sector is paving the way for the widespread application of high
voltage, high power dc-dc converters. The on-board chargers of the EV are required
to be bidirectional and lightweight. On the other hand, the off-board chargers must
be capable of providing a flexible output voltage range to adapt to a different type of
vehicles. With the expected high penetration of EV, the integration of RES into the
charging system is foreseen as a viable solution to reduce the burden on the electrical
grid [7-11]. Particularly, for the high power dc (fast) charging, the charging
efficiency has become a critical issue. From these perspectives, the overall
performance of future the power systems is largely determined by these converters.
On a more extreme outlook, the possible replacement of ac distribution
system by dc is being widely debated [8-10]. Correspondingly, within the smart grid
infrastructure, the dc-dc converter will be the main component that interfaces the dc
distribution voltages with the consumer appliances.
3
1.2 Challenges for High-Performance dc-dc Converter Operation
In all applications, the efficiency of the dc-dc converters is of utmost concern.
Thus, the conduction and switching losses must be reduced. Conventionally, the
hard switching PWM converters induce substantial switching losses, particularly at
high switching frequency. Nevertheless, the high-frequency operation is highly
desirable to reduce the size of the converter. On that account, the soft switching
technique is sought to reduce the switching losses and thus to improve the efficiency.
The existing soft switching converters apply zero voltage switching (ZVS), zero
current switching (ZCS) or zero voltage zero current switching (ZVZCS) techniques
to suppress these losses. Evidently, the ZVZCS provides improved loss reduction
capability as compared to the former due to manipulation of both the voltage and
current waveforms simultaneously.
However, the ZVZCS can only be achieved either at the cost of increased
component count (and the conduction losses) and more complex controller.
Furthermore, most converters with ZVZCS can only provide unidirectional power
flow capability [12] [13] [14-16]. Operational-wise, the change in the input voltage,
switching frequency or the loading of the converter disrupts the function of ZVZCS
[17-28]. Consequently, the efficiency of the converter is often compromised to allow
the converter to work in wider operating range.
Another issue of interest for the non-isolated dc-dc converter is the voltage
gain ratio. Unlike its isolated counterpart, which utilizes transformer that can be
concurrently used as a step-up mechanism, the nonisolated dc-dc converter has to
employ other means to increase its gain. The popular method is to utilize the
multilevel configuration, switched capacitor or coupled inductors. However, these
topologies cannot provide a competitive gain without significantly increasing their
component count and magnetic footprint. In addition, high gain converter comes with
a substantial trade-off in terms of efficiency [26, 29-31]. For example, the multilevel
topology cascades multiple converters units in series formation. As a result, the
4
overall efficiency, which is the multiplication of the efficiency of each converter
unit, is reduced. Furthermore, this configuration requires a large number of active
and passive components that result in higher conduction losses.
On the other hand, the coupled inductor based topology attains high gain by
manipulating the turn‘s ratio of the coupled inductors. On that account, the increase
in the turns ratio, requires more conductor, thus increases the I2R losses. In addition,
at high power, bigger magnetic circuit is required to accommodate the magnetic flux,
in order to achieve the same gain ratio. Thus, the core losses are increased
proportionally. As for the switched capacitor designs, multiple switched capacitor
cells are required to boost the gain ratio. Besides additional device losses, the
residual charges contribute to lower the efficiency.
In general, due to large number of switches in the above-mentioned
topologies, it is extremely difficult to integrate the soft switching cells into the
circuit. Since they could not exploit the advantages of the soft switching, most of
these high gain converters exhibit higher switching losses [25, 32]. Notwithstanding,
a small number of converters that integrate the soft switching fail to maintain it
consistently over the entire gain profile. This is primarily due to the extreme duty
ratio in which high gain converter operates [26, 29-31, 33].
1.3 Problem Statements
From the brief overview above, it can be inferred that the primary challenges
that the non-isolated dc-dc power converters are required to address are: 1) High-
efficiency operation in a wide operating range, 2) High step-up/step-down gain with
sustained soft switching capability, and 3) Simple configuration with lower
component count. In the recent literature, the nonisolated dc-dc converters are
widely investigated to maintain low switching losses and to achieve high-efficiency
5
operation. However, the high efficiency operation is achieved at the expense of
larger component count, higher control complexity or limited operational range. The
latter is formulated in the form of soft switching that is limited by the input voltage,
switching frequency or loading. In other cases, the converter only allows
unidirectional power flow, thus limiting the scope of their applications. On the other
hand, in many circumstances (EV, spacecraft), the high gain is required with
substantial constraint imposed on the size and weight of the converter. From this
viewpoint, the gain heightening in a (low-weight) transformer-less topology is a big
challenge by itself. By surveying the relevant literature, it is observed that the
existing group of high gain non-isolated dc-dc power converters cannot sustain a
high-efficiency operation over the entire operating range of gain ratio and power.
Also, most of these converters are not equipped with the soft switching feature so
that the switching losses could be suppressed consistently.
1.4 Objectives of Research
Given these drawbacks of the current state-of the art of non-isolated
bidirectional dc-dc converter argued in Section 1.2, this work sets two primary
objectives. They are summarized as follows.
(i) To design a high-efficiency non-isolated bidirectional dc-dc power
converter with soft switching (ZVZCS) capability. The latter is to be
implemented by an auxiliary network to reduce the switching losses in the
main switches. Most importantly, the ZVZCS must operate in a wide
range of input voltage, switching frequencyand loading, while
maintaining high efficiency. Besides, the converter is expected to be built
using low number of components.
(ii) To design a soft switching non-isolated bidirectional dc-dc power
6
converter that can provide high gain with high efficiency. The high gain
is realized by using an intermediate energy storage cell, with reduced size
and weight. In addition, the soft switching (ZVS) is to be implemented
over the entire operational duty cycle ratios.
Objectives (i) and (ii) are realized using two different circuits.
1.5 Scope of Research
To achieve the objectives of the research, this work is limited by the
following scopes:
(i) The topologies of non-isolated soft switching dc-dc converters that are
covered in the literature review in Chapter 2 are not exhaustive.
However, it provides a comprehensive classification so that the existing
circuits should fall under any of these categories.
(ii) The test results of the experimental prototype of the high-efficiency
converter in Chapter 3 are recorded at 150 W. Mainly, the low power
region allows analyzing the switching losses more effectively. This is
because the latter loss is more dominating than the conduction losses in
this region.
7
1.6 Organization of Thesis
This thesis is organized into five chapters. Their contents are outlined as
follows:
(i) Chapter 2 provides an extensive review of the soft switching techniques,
the soft switching converters and the gain boosting techniques employed
in non-isolated bidirectional dc-dc converters. The soft switching
techniques are divided into the ZVS, the ZCS, the ZVZCS and the true
ZVZCS. On the other hand, the soft switching converters are categorized
into the active and passive snubber, the series and shunt resonant and the
pulse width modulated converters. The merits and drawbacks of these
soft switching configurations are highlighted. Besides, the gain boosting
techniques are discussed along with their advantages and disadvantages.
(ii) Chapter 3 introduces the proposed non-isolated bidirectional dc-dc
converter family. The proposed converter employs a ZVZCS network to
improve the efficiency. Despite having a low component count and a
simple configuration, it is capable of maintaining the soft switching
condition for a wide operating range. Furthermore, it can be integrated to
other basic converter platforms to improve the efficiency and extend the
soft switching range.
(iii) Chapter 4 presents the proposed high gain and high efficiency non-
isolated bidirectional dc-dc converter. The converter is integrated with
the soft switching capability implemented by two identical auxiliary
resonant networks. The dedicated networks ensure the soft switching
over the whole operating condition. Resultantly, the high gain ratio is
achievable with high operating efficiency. Besides, the reverse recovery
loss is also eliminated.
(iv) Chapter 5 concludes the works undertaken and highlights the
8
contributions of this research. Several suggestions are provided for
possible directions of future work.
147
REFERENCES
1. S.-Y. Tseng, H.-Y. Wang, and C.-C. Chen (2013). PV power system using
hybrid converter for LED indictor applications. Energy Conversion and
Management, 75, 761-772.
2. Y.-M. Chen, Y.-C. Liu, and F.-Y. Wu (2002). Multi-input DC/DC converter
based on the multiwinding transformer for renewable energy applications.
IEEE Transaction of IndustrialApplications, 38, 1096-1104.
3. A. Kolli, A. Gaillard, A. De Bernardinis, O. Bethoux, D. Hissel, and Z.
Khatir (2015). A review on DC/DC converter architectures for power fuel
cell applications. Energy Conversion and Management, 105, 716-730.
4. M. Delshad and H. Farzanehfard (2011). A new soft switched push pull
current fed converter for fuel cell applications. Energy Conversion and
Management, 52, 917-923.
5. H. Mamur and R. Ahiska (2015). Application of a DC–DC boost converter
with maximum power point tracking for low power thermoelectric
generators. Energy Conversion and Management, 97, 265-272.
6. J. Kim and C. Kim (2013). A DC–DC boost converter with variation-
tolerant MPPT technique and efficient ZCS circuit for thermoelectric
energy harvesting applications. IEEE Transactions on Power Electronics,
28, 3827-3833.
7. A. R. Bhatti, Z. Salam, M. J. B. A. Aziz, K. P. Yee, and R. H. Ashique
(2016). Electric vehicles charging using photovoltaic: Status and
technological review. Renewable and Sustainable Energy Reviews, 54, 34-
47.
8. P. P. Barker and J. M. Bing (2005). Advances in solar photovoltaic
technology: an applications perspective. Power Engineering Society
General Meeting. 12 -16 Jun. San Francisco, CA, USA, 1955-1960.
148
9. L. Liu, F. Kong, X. Liu, Y. Peng, and Q. Wang (2015). A review on electric
vehicles interacting with renewable energy in smart grid. Renewable and
Sustainable Energy Reviews, 51, 648-66.
10. F. Mwasilu, J. J. Justo, E.-K. Kim, T. D. Do, and J.-W. Jung (2014).
Electric vehicles and smart grid interaction: A review on vehicle to grid and
renewable energy sources integration. Renewable and Sustainable Energy
Reviews, 34, 501-516.
11. Y.-M. Wi, J.-U. Lee, and S.-K. Joo (2013). Electric vehicle charging
method for smart homes/buildings with a photovoltaic system. IEEE
Transactions on Consumer Electronics, 59, 323-328.
12. B. Akin (2014). An Improved ZVT-ZCT PWM DC/DC Boost Converter
With Increased Efficiency. IEEE Transactions on Power Electronics, 29,
1919-1926.
13. Y. Park, B. Jung, and S. Choi (2012). Nonisolated ZVZCS Resonant PWM
DC/DC Converter for High Step-Up and High-Power Applications. IEEE
Transactions on Power Electronics, 27, 3568-3575.
14. I. Aksoy, H. Bodur, and A. F. Bakan (2010). A New ZVT-ZCT-PWM
DC/DC Converter. IEEE Transactions on Power Electronics, 25, 2093-
2105.
15. C. M. de Oliveira Stein and H. L. Hey (2000). A true ZCZVT commutation
cell for PWM converters. IEEE Transactions on Power Electronics, 15,
185-193.
16. S. Urgun (2012). Zero-voltage transition zero-current transition pulsewidth
modulation DC/DC buck converter with zero-voltage switching zero-
current switching auxiliary circuit. IET Power Electronics, 5, 627-634.
17. F. H. Khan and L. M. Tolbert (2007). A multilevel modular capacitor-
clamped DC–DC converter. IEEE Transactions on Industry Applications,
43, 1628-1638.
18. M. Gitau (2011). High efficiency multilevel switched-capacitor DC-DC
converters for interfacing DC-buses with separate ground. Proceedings of
the 37th IEEE IECON. 07-10 Nov. Melbourne, Vic, Australia: IEEE, 4421-
4426.
19. W. Qian, D. Cao, J. G. Cintrón-Rivera, M. Gebben, D. Wey, and F. Z. Peng
(2012). A switched-capacitor DC–DC converter with high voltage gain and
149
reduced component rating and count. IEEE Transactions on Industry
Applications, 48, 1397-1406.
20. X. Hu and C. Gong (2014). A high voltage gain dc–dc converter integrating
coupled-inductor and diode–capacitor techniques. IEEE Transactions on
Power Electronics, 29, 789-800.
21. A. A. A. Freitas, F. L. Tofoli, S. Júnior, E. Mineiro, S. Daher, and F. L. M.
Antunes (2015). High-voltage gain dc–dc boost converter with coupled
inductors for photovoltaic systems. IET Power Electronics, 8, 1885-1892.
22. S.-M. Chen, M.-L. Lao, Y.-H. Hsieh, T.-J. Liang, and K.-H. Chen (2015). A
Novel Switched-Coupled-Inductor DC–DC Step-Up Converter and Its
Derivatives. IEEE Transactions on Industry Applications, 51, 309-314.
23. X. Hu and C. Gong (2015). A high gain input-parallel output-series DC/DC
converter with dual coupled inductors. IEEE Transactions on Power
Electronics, 30, 1306-1317.
24. Y.-P. Hsieh, J.-F. Chen, L.-S. Yang, C.-Y. Wu, and W.-S. Liu (2014). High-
conversion-ratio bidirectional dc–dc converter with coupled inductor. IEEE
Transactions on Industrial Electronics, 61, 210-222.
25. M. L. a. S. Hemamalini (2017). Non-isolated High Gain DC-DC Converter
for DC Microgrids. IEEE Transactions on Industrial Electronics (In press).
26. G. Wu, X. Ruan, and Z. Ye (2015). Nonisolated High Step-Up DC–DC
Converters Adopting Switched-Capacitor Cell. IEEE Transactions on
Industrial Electronics, 62, 383-393.
27. Y. S. Lee and Y. Y. Chiu (2005). Zero-current-switching switched-capacitor
bidirectional DC-DC converter. IEE Proceedings - Electric Power
Applications, 152, 1525-1530.
28. H. S. Chung, A. Ioinovici, and C. Wai-Leung (2003). Generalized structure
of bi-directional switched-capacitor DC/DC converters. IEEE Transactions
on Circuits and Systems I: Fundamental Theory and Applications, 50, 743-
753.
29. F. Zhang, L. Du, F. Z. Peng, and Z. Qian (2008). A new design method for
high-power high-efficiency switched-capacitor dc–dc converters. IEEE
Transaction on Power Electronics, 23, 832-840, 2008.
150
30. M. Siddique, M. J. Ferdous, and I. Islam (2014). Switched capacitor based
soft-switching DC-DC boost converter for high voltage gain. Proceedings
of the 2014 IEEE ICECE. 20-22 Dec. Dhaka, Bangladesh: IEEE, 820-823.
31. H. Ardi, R. R. Ahrabi, and S. N. Ravadanegh (2014). Non-isolated
bidirectional DC/DC converter analysis and implementation. IET Power
Electronics, 7, 3033-3044.
32. M. Kwon, S. Oh, and S. Choi (2014). High gain soft-switching bidirectional
DC–DC converter for eco-friendly vehicles. IEEE Transactions on Power
Electronics, 29, 1659-1666.
33. H. Fathabadi (2016). Novel photovoltaic based battery charger including
novel high efficiency step-up DC/DC converter and novel high accurate fast
maximum power point tracking controller. Energy Conversion and
Management, 110, 200-211.
34. J. Doo-Yong, J. Young-Hyok, P. Sang-Hoon, J. Yong-Chae, and W. Chung-
Yuen (2011). Interleaved Soft-Switching Boost Converter for Photovoltaic
Power-Generation System. IEEE Transactions on Power Electronics, 26,
1137-1145.
35. E. Adib and H. Farzanehfard (2009). Soft switching bidirectional DC–DC
converter for ultracapacitor–batteries interface. Energy Conversion and
Management, 50, 2879-2884.
36. A. S. Samosir and A. H. M. Yatim (2010). Implementation of dynamic
evolution control of bidirectional DC–DC converter for interfacing
ultracapacitor energy storage to fuel-cell system. IEEE Transactions on
Industrial Electronics, 57, 3468-3473.
37. V. Fernão Pires, E. Romero-Cadaval, D. Vinnikov, I. Roasto, and J. F.
Martins (2014). Power converter interfaces for electrochemical energy
storage systems – A review. Energy Conversion and Management, 86, 453-
475.
38. A. K. Rathore, D. R. Patil, and D. Srinivasan (2015). A Non-Isolated
Bidirectional Soft Switching Current fed LCL Resonant DC/DC Converter
to Interface Energy Storage in DC Microgrid. IEEE Transactions on
Industry Applications, 52(2), 1711-1722.
39. G. Hua and F. C. Lee (1995). Soft-switching techniques in PWM
converters. IEEE Transactions on Industrial Electronics, 42, 595-603.
151
40. R. L. Steigerwald (1995). A review of soft-switching techniques in high
performance DC power supplies. Proceedings of the 1995 IEEE IECON, 6-
10th
Nov. Orlando, Fla., USA, 1, 1-7.
41. M. R. Amini and H. Farzanehfard (2009). Novel Family of PWM Soft-
Single-Switched DC/DC Converters With Coupled Inductors. IEEE
Transactions on Industrial Electronics, 56, 2108-2114.
42. H. Bodur and A. F. Bakan (2004). A new ZVT-ZCT-PWM DC-DC
converter. IEEE Transactions on Power Electronics, 19, 676-684.
43. C. A. Canesin and I. Barbi (1997). Novel zero-current-switching PWM
converters. IEEE Transactions on Industrial Electronics, 44, 372-381.
44. W. Chao-Cheng and Y. Chung-Ming (2003). New ZVT-PWM DC/DC
converters using active snubber. IEEE Transactions on Aerospace and
Electronic Systems, 39, 164-175.
45. T. Ching-Jung and C.-L. Chen (1998). Novel ZVT-PWM converters with
active snubbers. IEEE Transactions on Power Electronics, 13, 861-869.
46. T. Ching-Jung and C.-L. Chen (1998). A passive lossless snubber cell for
nonisolated PWM DC/DC converters. IEEE Transactions on Industrial
Electronics, 45, 593-601.
47. M. L. da Silva Martins and H. L. Hey (2004). Self-commutated auxiliary
circuit ZVT PWM converters. IEEE Transactions on Power Electronics, 19,
1435-1445.
48. S. Dusmez, A. Khaligh, and A. Hasanzadeh (2015). A Zero-Voltage-
Transition Bidirectional DC/DC Converter. IEEE Transactions on
Industrial Electronics, 62, 3152-3162.
49. R. C. Fuentes and H. L. Hey (1999). An improved ZCS-PWM commutation
cell for IGBT's application. IEEE Transactions on Power Electronics, 14,
939-948.
50. K. Fujiwara and H. Nomura (1999). A novel lossless passive snubber for
soft-switching boost-type converters. IEEE Transactions on Power
Electronics, 14, 1065-1069.
51. M. Hengchun, F. C. Y. Lee, Z. Xunwei, H. Dai, M. Cosan, and D.
Boroyevich (1997). Improved zero-current transition converters for high-
power applications. IEEE Transactions on Industry Applications, 33, 1220-
1232.
152
52. G. Hua, C. S. Leu, and F. C. Lee (1992). Novel zero-voltage-transition
PWM converters. Proceedings of the 1992 23rd IEEE PESC’92 Record., 29
Jun.-03 Jul., Toledo, Spain, 1, 55-61.
53. B. T. Irving and M. M. Jovanovic (2002). Analysis, design, and
performance evaluation of flying-capacitor passive lossless snubber applied
to PFC boost converter. Proceedings of the 2002 Seventeenth IEEE APEC.
10-14 Mar. Dallas, TX, USA, 1, 503-508.
54. B. Ivanovic and Z. Stojiljkovic (2004). A novel active soft switching
snubber designed for boost converter. IEEE Transactions on Power
Electronics, 19, 658-665.
55. Y. Jae-Won and D. Hyun-Lark (2014). Soft-Switching Bidirectional DC-
DC Converter Using a Lossless Active Snubber. IEEE Transactions on
Circuits and Systems I: Regular Papers. 61, 1588-1596.
56. L. Jiang, C. C. Mi, S. Li, M. Zhang, X. Zhang, and C. Yin (2013). A Novel
Soft-Switching Bidirectional DC–DC Converter with Coupled Inductors.
IEEE Transactions on Industry Applications, 49, 2730-2740.
57. M. M. Jovanovic and J. Yungtack (1999). A new, soft-switched boost
converter with isolated active snubber. IEEE Transactions on Industry
Applications, 35, 496-502.
58. M. M. Jovanovic and J. Yungtaek (2000). A novel active snubber for high-
power boost converters. IEEE Transactions on Power Electronics, 15, 278-
284.
59. N. Lakshminarasamma and V. Ramanarayanan (2007). A Family of
Auxiliary Switch ZVS-PWM DC/DC Converters with Coupled Inductor.
IEEE Transactions on Power Electronics, 22, 2008-2017.
60. A. Mirzaei, A. Jusoh, and Z. Salam (2012). Design and implementation of
high efficiency non-isolated bidirectional zero voltage transition pulse width
modulated DC–DC converters. Energy, 47, 358-369.
61. T. Mishima, S. Miyake, and M. Nakaoka (2010). Practical evaluations of
ZCS-PWM boost DC-DC converter with active edge-resonant cell using Si-
IGBT/SiC-SBD hybrid power devices. Proceedings of the 2010 5th IET
PEMD. 19-21 Apr. Brighton, United Kingdom, 1-6.
62. T. Mishima and M. Nakaoka (2010). A new family of soft switching PWM
non-isolated DC-DC converters with Active auxiliary Edge-Resonant Cell.
153
Proceedings of the 2010 5th IEEE IPEC. 21-24 Jun., Sapporo, Japan, 2804-
2809.
63. T. Mishima and M. Nakaoka (2013). A Practical ZCS-PWM Boost DC-DC
Converter With Clamping Diode-Assisted Active Edge-Resonant Cell and
Its Extended Topologies. IEEE Transactions on Industrial Electronics, 60,
2225-2236.
64. T. Mishima, Y. Takeuchi, and M. Nakaoka (2013). Analysis, Design, and
Performance Evaluations of an Edge-Resonant Switched Capacitor Cell-
Assisted Soft-Switching PWM Boost DC/DC Converter and Its Interleaved
Topology. IEEE Transactions on Power Electronics, 28, 3363-3378.
65. M. Mohammadi, E. Adib, and M. R. Yazdani (2015). Family of Soft-
Switching Single-Switch PWM Converters With Lossless Passive Snubber.
IEEE Transactions on Industrial Electronics, 62, 3473-348.
66. K. Ogura, S. Chandhaket, T. Ahmed, and M. Nakaoka (2003). Boost
chopper-fed ZVS-PWM DC-DC converter with parasitic oscillation surge
suppression-based auxiliary edge resonant snubber. Proceedings of the 25th
IEEE INTELEC '03. 20-23 Oct. Yokohama, Japan, 20-26.
67. D. Patil, A. K. Rathore, and D. Srinivasan (2015). A non-isolated
bidirectional soft switching current fed LCL resonant dc/dc converter to
interface energy storage in DC microgrid. Proceedings of the 2015 IEEE
APEC. 15-19 Mar. Charlotte, NC, USA, 709-716.
68. M. Pavlovsky, G. Guidi, and A. Kawamura (2014). Buck/boost DC–DC
converter topology with soft switching in the whole operating region. IEEE
Transactions on Power Electronics, 29, 851-862.
69. K. F. A. Sayed, T. Mishima, H. Sugimura, M. Sang-Pil, K. Soon-Kurl, and
M. Nakaoka (2009). Interleaved ZCS boost DC-DC converters with coupled
inductor using active edge resonant switch blocks for PV interface.
Proceedings of the 2009 IEEE ICEMS. 15-18 Nov. Tokyo, Japan, 1-7.
70. L. T. S. Sobrinho, R. A. Kitamura, and C. A. Canesin (1998). Novel zero-
current-switching PWM step down Sepic converter. Proceedings of the
1998 International Conference on Power Electronic Drives and Energy
Systems for Industrial Growth. 1-3 Dec. Perth, Australia: IEEE, 2, 717-722.
71. C. Tantisukarom, V. Tarateeraseth, W. Khan-ngern, and S. Nitta (2002). An
efficiency improvement of the active snubber boost converter for low
154
power. Proceedings of the 2002 IEEE 33rd PESC2. 23-27 Jun. Cairns, Qld.,
Australia, 2, 437-440.
72. F. T. Wakabayashi, M. J. Bonato, and C. A. Canesin (1999). A new family
of zero-current-switching PWM converter. Proceedings of the 1999 30th
IEEE PESC. 1-1 Jul. Charleston, SC, USA, USA, 1, 451-456.
73. C. M. Wang, H. J. Chiu, and D. R. Chen (2005). Novel zero-current-
switching (ZCS) PWM converters. IEE Proceedings - Electric Power
Application, 152, 407-415.
74. J. Zhang, J.-S. Lai, R.-Y. Kim, and W. Yu (2007). High-power density
design of a soft-switching high-power bidirectional dc–dc converter. IEEE
Transactions on Power Electronics, 22, 1145-1153.
75. J. Y. Zhu and D. Daohong (1999). Zero-voltage- and zero-current-switched
PWM DC-DC converters using active snubber. IEEE Transactions on
Industry Applications, 35, 1406-1412.
76. K. Zhuge and M. Kazerani (2014). A novel capacitor-switched active
snubber for single-module and interleaved two-module bidirectional buck-
boost converter topologies. Proceedings of the 40th IEEE IECON 2014. 29
Oct - 01 Nov. Dallas, TX, USA, 1097-1103.
77. M. R. Mohammadi and H. Farzanehfard (2016). A New Family of Zero-
Voltage-Transition Nonisolated Bidirectional Converters With Simple
Auxiliary Circuit. IEEE Transactions on Industrial Electronics, 63, 1519-
1527.
78. M. L. S. Martins and H. L. Hey (2004). Self-commutated auxiliary circuit
ZVT PWM converters. IEEE transactions on power electronics, 19, 1435-
1445.
79. W. Chien-Ming (2005).A New Family of Zero-Current-Switching (ZCS)
PWM Converters. IEEE Transactions on Industrial Electronics, 52, 1117-
1125.
80. W. Chien-Ming (2006). New family of zero-current-switching PWM
converters using a new zero-current-switching PWM auxiliary circuit. IEEE
Transactions on Industrial Electronics, 53, 768-777.
81. L. Dong-Yun, L. Min-Kwang, H. Dong-Seok, and I. Choy (2003). New
zero-current-transition PWM DC/DC converters without current stress.
IEEE Transaction on Power Electronics, 18, 95-104.
155
82. J.-W. Yang and H.-L. Do (2014). Soft-switching bidirectional DC-DC
converter using a lossless active snubber. IEEE Transactions on Circuits
and Systems I: Regular Papers, 61, 1588-1596.
83. P. Das, B. Laan, S. A. Mousavi, and G. Moschopoulos (2009). A
Nonisolated Bidirectional ZVS-PWM Active Clamped DC/DC Converter.
IEEE Transaction on Power Electronics, 24, 553-558.
84. A. Pressman (1998). Switching power supply design. (2nd
ed.) New York:
McGraw-Hill Inc.
85. S. Digital (2016). eZdsp F2812 Reference Technical-C2000 DSP
Development Tools. Retrieved on March 01, 2015, from
fttp://c2000.spectrumdigital.com/ezf2812/docs/ezf2812_techref.pdf
86. L. Guo (2006). Design and implementation of digital controllers for buck
and boost converters using linear and nonlinear control methods. Doctor
Philosophy, Auburn University, Auburn, Alabama, USA.
87. S. D. Bloom and R. P. Massey (1976). Emission Standards and Design
Techniques for EMI Control of Multiple DC-DC Converter Systems.
Proceedings of the 1976 International Symposium on Electromagnetic
Compatibility. 13-15 Jul. Washington, DC, USA, 1-5.
88. S. Park, H. A. Huynh, and S. Kim (2015). Analysis of EMI reduction
methods of DC-DC buck converter. Proceedings of the 2015 10th
International Workshop on the Electromagnetic Compatibility of Integrated
Circuits (EMC Compo). 10-13 Nov. Edinburg, UK: IEEE, 92-96.
89. S. Braun and P. Russer (2012). Requirements and solutions for emission
measurements in time-domain according to international EMC standards.
Proceedings of the 2012 APEMC. 21-24May, Singapore: IEEE, 209-212.
90. S. D. Bloom and R. P. Massey (1976). Emission standards and design
techniques for EMI control of multiple DC-DC converter systems.
Proceedings of the 1976 IEEE PESC. 8-10 Jun. Cleveland, OH, USA, 312-
317.
91. Y. Tang, H. Zhu, B. Song, J. S. Lai, and C. Chen (1998). EMI experimental
comparison of PWM inverters between hard- and soft-switching techniques.
Proceedings of the 1998 Power Electronics in Transportation. 22-23 Oct.
Dearborn, MI, USA:IEEE, 71-77.
156
92. Z. Huibin, L. Jih-Sheng, A. R. Hefner, T. Yuqing, and C. Chingchi (2001).
Modeling-based examination of conducted EMI emissions from hard and
soft-switching PWM inverters. IEEE Transaction on Industrial
Applications, 37, 1383-1393.
93. A. Mirzaei, A. Jusoh, Z. Salam, E. Adib, and H. Farzanehfard (2011).
Analysis and design of a high efficiency bidirectional DC–DC converter for
battery and ultracapacitor applications. Simulation Modelling Practice and
Theory, 19, 1651-1667.
94. Y. Lembeye, V. D. Bang, G. Lefevre, and J. Ferrieux (2009). Novel Half-
Bridge Inductive DC/DC Isolated Converters for Fuel Cell Applications.
IEEE Transaction on Energy Conversion, 24, 203-210.
95. A. K. Rathore and U. R. Prasanna (2013). Analysis, Design, and
Experimental Results of Novel Snubberless Bidirectional Naturally
Clamped ZCS/ZVS Current-Fed Half-Bridge DC/DC Converter for Fuel
Cell Vehicles. IEEE Transaction on Industrial Electronics, 60, 4482-4491.
96. F. Haifeng and L. Hui (2011). High-Frequency Transformer Isolated
Bidirectional DC/DC Converter Modules with High Efficiency over Wide
Load Range for 20 kVA Solid-State Transformer. IEEE Transaction on
Power Electronics, 26, 3599-3608.
97. R. P. Twiname, D. J. Thrimawithana, U. K. Madawala, and C. A. Baguley
(2014). A New Resonant Bidirectional DC/DC Converter Topology. IEEE
Transactions on Power Electronics, 29, 4733-4740.
98. R. P. Twiname, D. J. Thrimawithana, U. K. Madawala, and C. A. Baguley
(2015). A Dual-Active Bridge Topology with a Tuned Network. IEEE
Transactions on Power Electronics, 30, 6543-6550.
99. G. G. Oggier and M. Ordonez (2016). High-Efficiency DAB Converter
Using Switching Sequences and Burst Mode. IEEE Transactions on Power
Electronics, 31, 2069-2082.
100. B. Narasimharaju, S. P. Dubey, and S. Singh (2012). Design and analysis of
coupled inductor bidirectional DC–DC convertor for high-voltage diversity
applications. IET Power Electronics, 5, 998-1007.
101. H. Ardi, A. Ajami, F. Kardan, and S. N. Avilagh (2016). Analysis and
Implementation of a Nonisolated Bidirectional DC/DC Converter With
157
High Voltage Gain. IEEE Transaction on Industrial Electronics, 63, 4878-
4888.
102. K.-B. Park, G.-W. Moon, and M.-J. Youn (2010). Nonisolated high step-up
boost converter integrated with sepic converter. IEEE Transaction Power
Electronics, 25, 2266-2275.
103. D. Cao, S. Jiang, and F. Z. Peng (2011). Optimal design of multilevel
modular switched-capacitor dc-dc converter. Proceedings of the 2011 IEEE
ECCE. 17-22 Sep. Phoenix, AZ, USA, 537-544.
104. R.-J. Wai, R.-Y. Duan, and K.-H. Jheng (2012). High-efficiency
bidirectional dc–dc converter with high-voltage gain. IET Power
Electronics, 5, 173-184.
105. W. Liao, T. Liang, H. Liang, H. Liao, L. Yang, K. Juang, et al. (2011).
Study and implementation of a novel bidirectional DC-DC converter with
high conversion ratio. Proceedings of the 2011 ECCE. 17-22 Sep. Phoenix,
AZ, USA: IEEE, 134-140.
106. M. Lakshmi and S. Hemamalini (2017). Non-isolated High Gain DC-DC
Converter for DC Microgrids. IEEE Transaction on Industrial Electronics
(In press).
107. M. R. Mohammadi and H. Farzanehfard (2015). Analysis of Diode Reverse
Recovery Effect on the Improvement of Soft-Switching Range in Zero-
Voltage-Transition Bidirectional Converters. IEEE Transaction on
Industrial Electronics, 62, 1471-1479.