DESIGN ZERO-VOLTAGE SWITCHING DC-DC BUCK CONVERTER ROHAFIZA BINTI ABDULLAH A project report submitted in partial fulfillment of the requirement for the award of the Master of Electrical Engineering Faculty of Electrical and Electronics Engineering Universiti Tun Hussein Onn Malaysia JUNE 2014 v ABSTRACT This report proposes an integrated, high switching frequency, zero-voltage-switching dc-dc buck converter for battery charger application. The design and analysis of dc- dc buck converter with integrated inductor is presented. The converter has been optimized to convert 12V input voltage to 5V at 1.5A maximum load current at 50MHz switching frequency. The converter has been simulated using an ORCAD 16.5 based simulation tool and result show that the switching losses using zero- voltage-switching technique is less compared to conventional buck converter. vi ABSTRAK Projek ini mencadangkan rekabentuk litar pensuisan voltan-sifar penukar buck dc-dc untuk kegunaan penukar USB. Rekabentuk dan analisis dipersembahkan dengan litar bersepadu induktor. Litar penukar ini menukarkan voltan masukan 12V kepada voltan keluaran 5V dengan arus beban 1.5A pada frekuensi 50MHz. Litar dianalisa menggunakan perisian OrCAD Capture CIS dan berdasarkan hasil daripada simulasi litar menunjukkan kehilangan kuasa pensuisan menggunakan teknik pensuisan voltan-sifar lebih rendah berbanding dengan penukar buck konvensioanal. vii CONTENTS TITLE i DECLARATION ii DEDICATION iii ACKNOWLEDGEMENT iv ABSTRACT v ABSTRAK vi CONTENTS ix LIST OF TABLES x LIST OF FIGURES ix LIST OF SYMBOLS AND ABBREVIATIONS xii LIST OF APPENDICES xiii CHAPTER I INTRODUCTION 1 1.1 Overview 1 1.2 Problems Statement 2 1.3 Objective of project 3 1.4 Scope of project 3 CHAPTER II REVIEWS 5 2.1 Hard Switching and Soft Switching Background 5 2.2 Resonant Converter Overview 8 2.2.1 Zero Current Resonant Switch (ZCS) 9 2.2.2 Zero Voltage Resonant Switch (ZVS) 9 2.2.3 Comparisons Between ZCS and ZVS 9 2.3 Zero Voltage Switching research reviews 10 CHAPTER III METHODOLOGY 14 3.1 Proposed converter design 14 3.2 Resonant Converter Design 15 viii 3.2.1 Selection of Resonant Inductor and 16 Resonant Capacitor 3.2.2 Mode of operation 17 3.3 Selection of semiconductor switch 20 3.3.1 Bipolar Junction Transistor 23 3.3.2 Insulated Gated Bipolar Transistor 24 3.3.3 MOSFET 24 CHAPTER IV RESULT AND ANALYSIS RESULT 27 4.1 System modelling 27 4.2 System simulation 27 4.2.1 System simulation without resonant 28 4.2.2 System simulation resonant 30 CHAPTER V CONCLUSIONS 42 REFERENCES 44 VITA 46 APPENDICES 47 ix LIST OF TABLES 3.1 Resonant Converter Specifications 15 4.1 Value of output voltage, output current and power 31 losses at different frequency switching x LIST OF FIGURES 2.1 Typical Switching Trajectories of Power Switches 6 2.2 Typical Switching Waveforms 6 2.3 Classical Buck (DC-DC Converter) 10 2.4 Joung Resonant Converter Topology 11 2.5 The basic three phase resonant DC link converter 12 2.6 The main circuit of the implemented quasi-resonant 12 battery charger 2.7 ZVS Boost Converter circuit diagram 13 3.1 The proposed resonant converter circuit 15 3.2 Voltage conversion of the ZVS buck converter 16 3.3 Equivalent circuit of ZVS buck converter in operational 18 cycle 3.4 Summary of Semiconductor Switching Devices 20 3.5 Generalized Switching Waveform 21 3.6 Zero-voltage-switching converter schematic 22 3.7 Vertical Cross Section of MOSFET 25 4.1 Model Schematic Hard-Switching Converter 28 4.2 Output Voltage for System Without Resonant 29 4.3 Output Current for System Without Resonant 29 4.4 Switching Power Losses for System Without Resonant 29 4.5 Model Schematic Resonant Converter 30 4.6 Vgs, Vcr, and Ilr at frequency switching 50MHz 31 4.7 Switching power losses at frequency switching 50MHz 32 4.8 Output voltage at switching 50MHz 32 4.9 Output current at switching 50MHz 33 4.10 Vgs, Vcr, and Ilr at frequency switching 2MHz 33 4.11 Switching power losses at frequency switching 2MHz 34 xi 4.12 Output voltage at switching frequency 2MHz 34 4.13 Output current at switching frequency 2MHz 34 4.14 Vgs, Vcr, and Ilr at frequency switching 75MHz 35 4.15 Switching power losses at frequency switching 75MHz 35 4.16 Output voltage at switching 75MHz 36 4.17 Output current at switching frequency 75MHz 36 4.18 Vgs, Vcr, and Ilr at frequency switching 100MHz 37 4.19 Switching power losses at frequency switching 100MHz 37 4.20 Output voltage at switching 100MHz 38 4.21 Output current at switching frequency 100MHz 38 4.22 Vgs, Vcr, and Ilr at frequency switching 100MHz 39 4.23 Switching power losses at frequency switching 250MHz 39 4.24 Output voltage at switching 250MHz 40 4.25 Output current at switching frequency 250MHz 40 4.26 Switching power losses for various switching frequency 41 xii LIST OF SYMBOLS AND ABBREVIATIONS DC Direct Current AC Alternating Current PWM Pulse Width Modulation BJT Bipolar Junctions Transistor IGBT Insulated Gate Bipolar Junction MOSFET Metal Oxide Semiconductor Field-Effect Transistor ZCS Zero Current switching ZVS Zero Voltage Switching LC Inductor Capacitor V Input Voltage s L Resonant Inductor r C Resonant Capacitor r f Switching Frequency s f Resonant Frequency o V Output Voltage o I Output Current o L Output Ripple Inductor / Filter Inductor e C Output Ripple Capacitor / Filter Capacitor f xiii LIST OF APPENDICES APPENDIX TITLE PAGE A Project Activities Flowchart 47 B Gantt Chart 48