Abstract: This paper proposes a new modular flexible power electronic transformer (FPET). The proposed FPET is flexible enough to meet future needs of power electronic centralized systems. The main feature of the FPET is the independent operation of modules each of which contains one port. Each port can be considered as input or output, because bidirectional power flow is provided. The modules are connected to a common dc link that facilitates energy transfer among modules as well as ports. Therefore, a multiport system is developed, which the ports can operate independently. This merit is important for applications, where input and output voltages are different in many parameters. A comparison study is carried out to clarify the pros

I would like to express my deepest gratitude to my advisor, Professor Mohan, firstly for giving me this opportunity to work in his research group and for guiding me through my graduate studies. It has been an honor to be Professor Mohan’s student and teaching assistant. Without his valuable advice, excellent teaching and encouragement, this thesis would not have been possible. I would like to thank my committee members, Professor Wollenberg, Professor Rob-bins and Professor Bobkov for their support and for being part of my PhD exam com-mittee. I would like to thank my colleagues at the lab who have knowingly or unknowingly helped me become a better engineer- Ranjan and Dr. Krushna Mohaparta for getting me started on this innovative project, Hari for teaching me to debug circuits, Apurva for teaching me to believe in myself, Kaushik for teaching me how to write technical papers, Saurabh for always being there to bounce ideas off and Dr. Chris Henze for his invaluable practical advice. I have learned so much from Dr. Dinkar Prasad, Dr.

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ABSTRACT-This paper suggests a novel strategy, for control of the power flow for a smart micro-grid. The utility grid power is dynamically controlled by a Power Electronic Transformer (PET). A 50Hz, step-down transformer is generally used at the Point of Common Coupling (PCC), to connect the micro-grid to the power system grid. Substitution of the conventional 50Hz transformer, by a PET, results in enhanced micro-grid power management system, during grid-connected operation. The smart micro-grid is a set of controllable loads and Distributed Energy Resources (DER); both renewable and non-renewable; that supply demand of a group of customers. The proposed dynamic power limiter (also referred to as PET) is a high-frequency, isolated power-converter system, comprised of a high- frequency step-down transformer and three-phase to single-phase matrix converters. The matrix converters are modulated with a novel Pulse Width Modulation (PWM) strategy for a bi-directional power flow control. The output of the matrix converter generates a high frequency (few kHz) pulsating single phase AC at the primary and secondary of the transformer, which are phase shifted for active power control. The PET also allows voltage regulation by control of reactive power. The entire system; represented as two, three-phase AC systems with an intermediate

I want to express my profound gratitude to Professor Mohan for being my advi-sor. I really appreciate his encouragement and relentless support particularly in difficult times. He always listened to my ideas and discussions with him led to key insights. His commitment to teaching is an inspiration to any one like me who aspires to be a teacher. Above all, he made me feel a friend, which I appreciate from the bottom of my heart. I express my heartfelt thanks to Professor Robbins for giving me an opportu-nity to teach courses and being supportive at all times. I consider myself fortunate to work with Professor Wollenburg during faculty workshops. I am grateful to Professor Anderson for interesting discussions in mathematics. I appreciate the financial support provided by Office of Naval research. I thank Mr Dan Dobrick for the support extended in procuring components. I would specially like to thank Mohapatra for introducing to the idea of power electronic transformers. I am grateful to Dr Chris Henze and professor D.T. Shahani for their time and helpful discussions during the hardware implementation of this project. I thank Hari, Apurva, Shanker, Rohit, Viswesh, Ruben and Ashish for their