University of Central Florida STARS Electronic Theses and Dissertations, 2004-2019 2007 Modeling And Digital Control Of High Frequency Dc-dc Power Converters Yangyang Wen University of Central Florida Part of the Electrical and Electronics Commons Find similar works at: https://stars.library.ucf.edu/etd University of Central Florida Libraries http://library.ucf.edu This Doctoral Dissertation (Open Access) is brought to you for free and open access by STARS. It has been accepted for inclusion in Electronic Theses and Dissertations, 2004-2019 by an authorized administrator of STARS. For more information, please contact [email protected]. STARS Citation Wen, Yangyang, "Modeling And Digital Control Of High Frequency Dc-dc Power Converters" (2007). Electronic Theses and Dissertations, 2004-2019. 3407. https://stars.library.ucf.edu/etd/3407 MODELING AND DIGITAL CONTROL OF HIGH FREQUENCY DC-DC POWER CONVERTERS by YANGYANG WEN B.E., Chongqing University, P. R. China, 1996 M.S., Chongqing University, P. R. China, 1999 M.S., University of Central Florida, USA, 2004 A dissertation submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy in the School of Electrical Engineering and Computer Science in the College of Engineering and Computer Science at the University of Central Florida Orlando, Florida Spring Term 2007 Major Professor: Issa Batarseh © 2007 Yangyang Wen ii ABSTRACT The power requirements for leading edge digital integrated circuits have become increasingly demanding. Power converter systems must be faster, more flexible, more precisely controllable and easily monitored. Meanwhile, in addition to control process, the new functions such as power sequencing, communication with other systems, voltage dynamic programming, load line specifications, phase current balance, protection, power status monitoring and system diagnosis are going into today’s power supply systems. Digital controllers, compared with analog controllers, are in a favorable position to provide basic feedback control as well as those power management functions with lower cost and great flexibility. The dissertation gives an overview of digital controlled power supply systems by comparing with conventional analog controlled power systems in term of system architecture, modeling methods, and design approaches. In addition, digital power management, as one of the most valuable and “cheap” function, is introduced in Chapter 2. Based on a leading-edge digital controller product, Chapter 3 focuses on digital PID compensator design methodologies, design issues, and optimization and development of digital controlled single-phase point-of-load (POL) dc-dc converter. Nonlinear control is another valuable advantage of digital controllers over analog controllers. Based on the modeling of an isolated half-bridge dc-dc converter, a nonlinear control method is proposed in Chapter 4. Nonlinear adaptive PID compensation scheme is implemented based on digital controller Si8250. The variable PID coefficient during transients improves power system’s transient response and thus output capacitance can be reduced to save cost. In iii Chapter 5, another nonlinear compensation algorithm is proposed for asymmetric flyback- forward half bridge dc-dc converter to reduce the system loop gain’s dependence on the input voltage, and improve the system’s dynamic response at high input line. In Chapter 6, a unified pulse width modulation (PWM) scheme is proposed to extend the duty-cycle-shift (DCS) control, where PWM pattern is adaptively generated according to the input voltage level, such that the power converter’s voltage stress are reduced and efficiency is improved. With the great flexibility of digital PWM modulation offered by the digital controller Si8250, the proposed control scheme is implemented and verified. Conclusion of the dissertation work and suggestions for future work in related directions are given in final Chapter. iv This document is dedicated to my parents. v ACKNOWLEDGMENTS I would like to express my sincere appreciation to my advisor, Dr. Issa Batarseh, for his for his guidance, encouragement and support. Dr. Issa Batarseh’s extensive vision and creative thinking have been the source of inspiration for me throughout this work. His personality and management experience are examples for me. I am grateful to my committee members, Dr. Louis Chow, Dr. Wasfy Mikhael, Dr. Christopher Iannello, Dr. Takis Kasparis, Dr. Jiann S. Yuan and Dr. Thomas Wu for their valuable suggestions and numerous help. It was a great pleasure to work in the Power Electronics Laboratory at the University of Central Florida Center. I am truly indebted to Dr. Hong Mao, Dr. Jaber A. Abu Qahouq, Dr. Shiguo Luo, Dr. Weihong Qiu, for their valuable guidance and help, made this dissertation possible. I would also like to acknowledge my team members Dr. Songquan Deng , Osama Abdul-Rahman, Liangbin Yao, Shangyang Xiao for their useful discussion and support. I would like to thank the digital power group in Silabs, Don Alfano, Ka leung and Jinwen Xiao. It is a pleasure to work with such a talented, hard-working and creative group. And I also like to express my gratitude to my friends, Jinwen Xiao, Yufang Jin, Alex Cai, Xiaolin Guo, their friendship and help have made my stay in Austin pleasant and enjoyable. My heartfelt appreciation goes toward my family who has always been there with their love and encouragement. Yangyang Wen March 2007 vi TABLE OF CONTENTS LIST OF FIGURES ....................................................................................................................... xi LIST OF TABLES...................................................................................................................... xvii 1 INTRODUCTION ....................................................................................................................... 1 1.1 Background and Motivations.......................................................................................... 1 1.2 Dissertation Outline and Major Results.......................................................................... 9 2 ANALOG AND DIGITAL CONTROLLED DC-DC CONVERTERS ................................... 13 2.1 Introduction................................................................................................................... 13 2.2 Modeling of High Frequency Switching DC-DC Converters....................................... 14 2.3 Analog Controlled DC-DC Converters......................................................................... 21 2.4 Digital Controlled Power Converter and Theoretical Basis ......................................... 25 2.5 Digital Controller Design Methodology ....................................................................... 31 2.6 Digital Power System Management.............................................................................. 41 2.7 Summary....................................................................................................................... 47 3 ALGORITHMS AND DESIGN OPTIMIZATION BASED ON DIGITAL CONTROLLER SI8250........................................................................................................................................... 49 3.1 Introduction................................................................................................................... 49 3.2 Digital control design for power converters ................................................................. 51 3.3 Digital Controller Design Case Study........................................................................... 58 3.4 Digital PID Coefficients Optimization and Limitation................................................. 64 3.4.1 Optimization of Digital Coefficients ........................................................................ 64 3.4.2 ADC and DPWM design considerations .................................................................. 72 vii 3.4.3 Limitation and calculation error of digital coefficients ............................................ 76 3.5 Digital controller Si8250 introduction.......................................................................... 83 3.5.1 Si8250 overview....................................................................................................... 83 3.5.2 System operation....................................................................................................... 85 3.5.3 ADC and Reference DAC......................................................................................... 87 3.5.4 Si8250 filter engine................................................................................................... 88 3.5.5 DPWM ...................................................................................................................... 90 3.5.6 System Management Processor ................................................................................ 93 3.6 Digital controller design implementation – Single-phase POL converter.................... 94 3.6.1 Hardware and specification overview....................................................................... 94 3.6.2 Control loop design................................................................................................... 97 3.6.3 Non-linear transient response control ..................................................................... 103 3.6.4 Experiment results.................................................................................................. 104 3.7 Summary....................................................................................................................