ABSTRACT ZHOU, XIAOHU. Design and Control of Bi-Directional Grid
Total Page:16
File Type:pdf, Size:1020Kb
ABSTRACT ZHOU, XIAOHU. Design and Control of Bi-Directional Grid-Interactive Converter for Plug- in Hybrid Electric Vehicle Applications. (Under the direction of Dr. Alex Q. Huang). The plug-in hybrid electric vehicle (PHEV) is a promising technology which provides a sustainable approach to transportation that is easily accessible to a large portion of the population that already relies on gasoline-fueled cars. Although the larger scale adoption of plug-in hybrid vehicles is still years away, politicians, electric utilities, and auto companies are eagerly awaiting the opportunities that will arise from reduced emissions, reduced gasoline consumption, new electric utility services, increased revenues, and new markets that will lead to the creation of new jobs. In addition, the electrification of the transportation system would lead to the creation of new avenues for researchers. In the case of power electronics researchers, plug-in hybrid electric vehicles would provide a new candidate for energy storage. Because energy storage is a component of so called “smart grids,” a topic of growing interest to the power engineering research community, PHEVs could be incorporated as a vital part of such a system. However, to enable this functionality, a power electronics interface between the vehicle and grid is required. The motivation of this dissertation is to design a grid-interactive smart charger to enable PHEV as distributed energy storage device which will play an important role in smart grid applications. For grid-connection applications of the proposed converter, adaptive virtual resistor control is proposed to achieve high power quality for plug-in hybrid electric vehicles integration with various grid conditions. High frequency resonance poses a challenge to controller design and moreover the various impedances lead to the variation of the resonant frequency which will make the control design more complicated. The proposed controller behaves as a controllable resistor series with a filter capacitor but does not exist physically. It will be adjusted automatically based on grid conditions in order to eliminate high frequency resonance. For off-grid applications of the proposed converter, a new inductor current feedback controller based on active harmonic injection is proposed. An active harmonics injection loop is proposed to extract the harmonics from the load and add to the inductor current control loop. This method effectively improves the harmonics compensation capability for the inductor current feedback control and achieves a better output voltage with nonlinear loads. For a Solid State Transformer (SST) based smart grid with multiple plug-in hybrid electric vehicles, the instability issue is investigated. When the total demand power from the plug-in vehicles exceeds the capability of one SST, a new power management strategy is proposed in each vehicle to adjust its power demand in order to avoid voltage collapse of the SST. Gain scheduling technique is proposed to dispatch power to each vehicle based on battery’s state of charge. A comprehensive case study is conducted to verify the proposed method. The proposed method can be used as a power electronics converter level control to improve the stability of a solid state transformer. For the DC/DC stage of the proposed converter a high order filter is proposed to be placed between the battery and the converter. The objective is to reduce the filter size which will further reduce the system cost and volume. Another major goal is to largely attenuate the current ripple of the charging current which will yield ripple free charging for a battery. Ripple free charging will eliminate the extra heat generated by the current ripple and will increase the battery life. The new controller is proposed to resolve the potential instability issue resulting from the high order filter. The control loop design and robustness analyses are conducted. Design and Control of Bi-Directional Grid-Interactive Converter for Plug-in Hybrid Electric Vehicle Applications by Xiaohu Zhou A dissertation submitted to the Graduate Faculty of North Carolina State University in partial fulfillment of the requirements for the degree of Doctor of Philosophy Electrical Engineering Raleigh, North Carolina 2011 APPROVED BY: _______________________________ ______________________________ Dr. Alex Q. Huang Dr. Mo-Yuen Chow Committee Chair ________________________________ ________________________________ Dr. Subhashish Bhattacharya Dr. Srdjan Lukic ii DEDICATION To My Parents Lili Huang and Zhigang Zhou iii BIOGRAPHY The author, Xiaohu Zhou, was born in Harbin, China. He received the B.S. and the M.S. degree from Harbin Institute of Technology, Harbin, China in 2004 and 2006, respectively, both in electrical engineering. Since fall of 2006, he started to pursue a Ph.D. degree at Semiconductor Power Electronics Center (SPEC) and later National Science Foundation funded Engineering Research Center: Future Renewable Electric Energy Delivery and Management Center (FREEDM), Department of Electrical and Computer Engineering, North Carolina State University, Raleigh. iv ACKNOWLEDGMENTS I would like to express my sincere appreciation to my advisor Dr. Alex Q. Huang for his guidance, encouragement and support. Dr. Huang’s creative thinking, broad knowledge, insightful vision and warm character always inspires my work and study. To explore something new will always be rooted in my heart. Thank you for giving me this opportunity, I enjoy my study and work in FREEDM Systems Center very much. I am very grateful to my other committee members, Dr. Mo-Yuen Chow, Dr. Subhashish Bhattacharya and Dr. Srdjan Lukic for their valuable suggestion and helpful discussion during so many group and individual meetings. It is my great pleasure to work with you during these five years. I would like also to thank Dr. Gracious Ngaile for serving as the Graduate School Representative for my defense. I want to thank ERC program of the National Science Foundation and Advanced Transportation Energy Center for their financial support of my project and research. I would like to thank all the staff members at FREEDM Systems Center who provide an amazing environment for me to study and work. Special thanks go to Mr. Anousone Sibounheuang and Mrs. Colleen Reid for their help. I want to thank my student colleagues who have helped with many good discussions and gave me so many joyful times: Dr. Chong Han, Dr. Yan Gao, Dr. Bin Chen, Dr. Wenchao Song, Dr. Xiaojun Xu, Dr. Jinseok Park, Dr. Jeesung Jung, Dr. Yu Liu, Dr. Jun Wang, Dr. Jiwei Fan, Dr. Liyu Yang, Dr. Sungkeun Lim, Dr. Xin Zhou, Dr. Tiefu Zhao, Dr. Jun Li, Dr. Rong Guo, Dr. Xiaopeng Wang, Mr. Zhaoning Yang, Mr. Jifeng Qin, Mrs. Zhengping Xi, Mr. Sameer Mundkur, Mr. Zhigang Liang, Mr. Yu Du, Mr. Qian Chen, Mr. Gangyao Wang, v Mr. Xunwei Yu, Mr. Edward Van Brunt, Mr. Babak Parkhideh, Mr. Arvind Govindaraj, Mr. Sanzhong Bai, Mr. Zeljko Pantic, Mr. Xu She, Mr. Xingchen Yang, Mr. Yen-Mo Chen, Mr. Pochin Lin, my Project Partner Mr. Philip Funderburk, Mr. Zhuoning Liu, Miss. Zhan Shen, Miss. Mengqi Wang, Mr. Yalin Wang, Mr. Xing Huang, Mr. Li Jiang, Mr. Fei Wang, Mr. Kai Tan, Mr. Xiang Lu. Finally I want to give my heartfelt appreciation to my parents in China. You always encourage me to pursue my dreams and help me get through tough times. I am so grateful to you for your endless support, trust and love for all of these years. vi TABLE OF CONTENTS LIST OF TABLES ................................................................................................................... ix LIST OF FIGURES .................................................................................................................. x Chapter One Introduction ......................................................................................................... 1 1.1 Research Background: Plug-in Hybrid Electric Vehicles ....................................... 1 1.2 State of the Art of Technology ................................................................................ 7 1.2.1 Survey of SAE Standards for Battery Chargers ............................................ 7 1.2.2 Battery Charger Classifications .................................................................... 9 1.2.3 Bi-directional Charger Topology and Charging Station ............................. 12 1.2.4 Overview of Vehicle to Grid (V2G) Technology ....................................... 15 1.3 Research Motivation: Enable Integration of Distributed Energy Storage Devices (Plug-in Hybrid Electric Vehicles) with Smart Grid ...................................................... 16 1.4 Contributions and Dissertation Outline ................................................................. 19 Chapter Two Design a Grid-Interactive Converter for Plug-in Hybrid Electric Vehicles ......... .......................................................................................................................................... 23 2.1 Definition of Grid-Interactive Converter .............................................................. 23 2.2 Topology Selection of Proposed Grid-Interactive Converter ................................ 25 2.3 Power Stage Design of Proposed Converter ......................................................... 29 2.3.1 Passive Components Design ....................................................................... 29 2.3.2 Efficiency Test ............................................................................................ 34 2.4