Methodology for combined Integration of electric vehicles and distributed resources into the electric grid

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2011.Cataloged from PDF version of thesis.Includes bibliographical references (p. 125-131).Plug-in electric vehicles and distributed generation are expected to appear in growing numbers over the next few decades. Large scale unregulated penetration of plug-in electric vehicles and distributed generation can each have detrimental impact on the existing electric grid infrastructure. However, appropriate pairing of the two technologies along with some storage could mitigate their individual negative impacts. This thesis develops a methodology and an optimization tool for the design of grid connected electric vehicle chargers that integrate distributed generation and storage into a single system. The optimization tool is based on a linear programming approach that identifies designs with the minimum system lifecycle cost. The thesis also develops the component and system cost models needed for this optimization. The tool can handle single and multiple charger systems with centralized or distributed generation and storage. To verify the tool's accuracy, a search-based optimization technique that works for single chargers with centralized generation and storage is also developed and used to validate the tool. To demonstrate the usefulness of the optimization tool, it is used to design optimal architectures for a single-charger residential charging case and a multi-charger public charging case. It is shown that designs that draw the maximum available power from the grid have the lowest 20-year system lifecycle cost. When storage is needed because the grid cannot provide full charging power, optimal designs may or may not include solar PV based distributed generation depending on the location. For example, in locations with solar irradiation profiles like Los Angeles, CA, electric vehicle charger designs that include solar PV generation are optimal, while in locations like Eugene, OR, optimal designs do not include solar PV. It is also shown that with the available technology, wind turbines are not cost effective for use in residential chargers in locations with wind speeds similar to Los Angeles, CA and Boulder, CO. For the multicharger public charging case, designs with centralized storage and generation are optimal.by Samantha Joellyn Gunter.S.M

Methodology for the optimal design of PEV charging systems with multiple chargers and distributed resources

Increased penetration of plug-in electric vehicles (PEVs) will necessitate deployment of numerous PEV chargers. Pairing these chargers with renewable distributed generation (DG) and storage can potentially alleviate negative impacts on the distribution grid and help meet renewable portfolio goals. The optimal design of such integrated charging systems depends on many factors, including geographic location and charging profiles. This paper presents an optimization methodology for designing integrated PEV charging systems with multiple chargers and distributed resources. This methodology is used to investigate optimal designs for charging systems at a retail business and on a university campus. When PEV charging can introduce a demand charge, it is shown that the optimal design depends on the time of charging and the level of existing load. When non-negligible distribution system losses exist between charger locations, it is shown that the optimal size and location of DG and storage depends on the charging profile of the different chargers and the distribution efficiency.Siemens Corporatio

Design and evaluation of a reconfigurable stacked active bridge dc/dc converter for efficient wide load-range operation

This paper presents the design and implementation of a large-step-down soft-switched dc-dc converter based on the active bridge technique which overcomes some of the limitations of the conventional Dual Active Bridge (DAB) converter. The topology comprises a double stacked-bridge inverter coupled to a reconfigurable rectifier through a special three-winding leakage transformer. This particular combination of stages enable the converter to run in an additional low-power mode that greatly increases light-load efficiency by reducing core loss and extending the zero-voltage switching (ZVS) range. The converter is implemented with a single compact magnetic component, providing power combining, voltage transformation, isolation, and energy transfer inductance. A 175 kHz, 300 W, 380 V to 12 V GaN-based prototype converter achieves 95.9% efficiency at full load, a peak efficiency of 97.0%, an efficiency above 92.7% down to 10% load and an efficiency above 79.8% down to 3.3% load.National Science Foundation (U.S.) (Award Number 1307699)MIT Skoltech Initiativ

Impedance Control Network Resonant Step-Down DC-DC Converter Architecture

In this paper, we introduce a step-down resonant dc-dc converter architecture based on the newly-proposed concept of an Impedance Control Network (ICN). The ICN architecture is designed to provide zero-voltage and near-zero-current switching of the power devices, and the proposed approach further uses inverter stacking techniques to reduce the voltages of individual devices. The proposed architecture is suitable for large-step-down, wide-input-range applications such as dc-dc converters for dc distribution in data centers. We demonstrate a first-generation prototype ICN resonant dc-dc converter that can deliver 330 W from a wide input voltage range of 260 V – 410 V to an output voltage of 12 V.MIT Skoltech InitiativeMIT Energy InitiativeNational Science Foundation (U.S.) (Award 1307699)Texas Instruments Incorporated (Graduate Women's Fellowship for Leadership in Microelectronics

Investigation and application of high-efficiency large-step-down power conversion architectures

Thesis: Ph. D., Massachusetts Institute of Technology, Department of Electrical Engineering and Computer Science, 2016.This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.Cataloged from student-submitted PDF version of thesis.Includes bibliographical references (pages 355-360).In this thesis, we introduce two large-step-down dc-dc converter architectures that are designed to provide zero-voltage switching of the power devices. While the techniques used in these converters can be used in a wide range of applications, the operating voltage and power levels used in this thesis are for data centers, where dc distribution power delivery is expected to see its first deployment. The nominal 380 V bus voltage will need to be converted to 12 V using a high-efficiency dc-dc converter that can deliver several hundred watts of power to each rack to power the servers. The converters are expected to operate efficiently across a wide input voltage range of 260 V to 410 V and down to powers in the tens of watts range. The first converter architecture is based on the concept of an Impedance Control Network (ICN) resonant converter. Using phase-shift control along with a specifically designed impedance network, this converter can maintain resistive loading of the inverters as the input voltage varies. To back down in power, the converter can be efficiently operated using burst (on/off) mode control. To deliver lower power, we introduce an additional control technique using Variable Frequency Multiplier (VFX) inverters and/or rectifiers. The second converter architecture combines the properties of an active bridge converter with multiple stacked inverters, a multi-winding single core transformer, and a reconfigurable rectifier. The stacked inverter topology improves the range of powers over which zero-voltage switching can be achieved. The multi-winding transformer and reconfigurable rectifier further extend the efficient operating range to very low powers by reducing core loss and increasing zero-voltage switching capability. Both proposed architectures are suitable for large-step-down, wide-input voltage, wide-output power applications such as dc-dc converters for dc distribution.by Samantha Joellyn Gunter.Ph. D

Optimal Design of Grid-Connected PEV Charging Systems With Integrated Distributed Resources

The penetration of plug-in electric vehicles and renewable distributed generation is expected to increase over the next few decades. Large scale unregulated deployment of either technology can have a detrimental impact on the electric grid. However, appropriate pairing of these technologies along with some storage could mitigate their individual negative impacts. This paper presents a framework and an optimization methodology for designing grid-connected systems that integrate plug-in electric vehicle chargers, distributed generation and storage. To demonstrate its usefulness, this methodology is applied to the design of optimal architectures for a residential charging case. It is shown that, given current costs, maximizing grid power usage minimizes system lifecycle cost. However, depending upon the location's solar irradiance patterns, architectures with solar photovoltaic generation can be more cost effective than architectures without. Additionally, Li-ion storage technology and micro wind turbines are not yet cost effective when compared to alternative solutions.Siemens Corporatio