A multilevel energy buffer and voltage modulator for grid-interfaced micro-inverters

Micro-inverters operating into the single-phase grid from solar photovoltaic (PV) panels or other low-voltage sources must buffer the twice-line-frequency variations between the energy sourced by the PV panel and that required for the grid. Moreover, in addition to operating over wide average power...

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Main Authors: Chen, Minjie, Perreault, David J., Afridi, Khurram
Other Authors: Massachusetts Institute of Technology. Department of Electrical Engineering and Computer Science
Format: Article
Language:en_US
Published: Institute of Electrical and Electronics Engineers (IEEE) 2014
Online Access:http://hdl.handle.net/1721.1/90544
https://orcid.org/0000-0003-0705-563X
https://orcid.org/0000-0002-0746-6191
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author Chen, Minjie
Perreault, David J.
Afridi, Khurram
author2 Massachusetts Institute of Technology. Department of Electrical Engineering and Computer Science
author_facet Massachusetts Institute of Technology. Department of Electrical Engineering and Computer Science
Chen, Minjie
Perreault, David J.
Afridi, Khurram
author_sort Chen, Minjie
collection MIT
description Micro-inverters operating into the single-phase grid from solar photovoltaic (PV) panels or other low-voltage sources must buffer the twice-line-frequency variations between the energy sourced by the PV panel and that required for the grid. Moreover, in addition to operating over wide average power ranges, they inherently operate over a wide range of voltage conversion ratios as the line voltage traverses a cycle. These factors make the design of micro-inverters challenging. This paper presents a multilevel energy buffer and voltage modulator (MEB) that significantly reduces the range of voltage conversion ratios that the dc-ac converter portion of the micro-inverter must operate over by stepping its effective input voltage in pace with the line voltage. The MEB also functions as an active energy buffer to reduce the twice-line-frequency voltage ripple at the output of the solar panel. The small additional loss of the MEB can be compensated by the improved efficiency of the dc-ac converter stage, leading to a higher overall system efficiency. A prototype micro-inverter incorporating a MEB, designed for 27 V to 38 V dc input voltage, 230 V rms ac output voltage, and rated for line cycle average power of 70 W, has been built and tested in grid-connected mode. It is shown that the MEB can successfully enhance the performance of a single-phase grid-interfaced micro-inverter by increasing its efficiency and reducing the total size of the twice-line-frequency energy buffering capacitance.
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spelling mit-1721.1/905442022-09-26T15:35:24Z A multilevel energy buffer and voltage modulator for grid-interfaced micro-inverters Chen, Minjie Perreault, David J. Afridi, Khurram Massachusetts Institute of Technology. Department of Electrical Engineering and Computer Science Massachusetts Institute of Technology. School of Engineering Chen, Minjie Afridi, Khurram Perreault, David J. Micro-inverters operating into the single-phase grid from solar photovoltaic (PV) panels or other low-voltage sources must buffer the twice-line-frequency variations between the energy sourced by the PV panel and that required for the grid. Moreover, in addition to operating over wide average power ranges, they inherently operate over a wide range of voltage conversion ratios as the line voltage traverses a cycle. These factors make the design of micro-inverters challenging. This paper presents a multilevel energy buffer and voltage modulator (MEB) that significantly reduces the range of voltage conversion ratios that the dc-ac converter portion of the micro-inverter must operate over by stepping its effective input voltage in pace with the line voltage. The MEB also functions as an active energy buffer to reduce the twice-line-frequency voltage ripple at the output of the solar panel. The small additional loss of the MEB can be compensated by the improved efficiency of the dc-ac converter stage, leading to a higher overall system efficiency. A prototype micro-inverter incorporating a MEB, designed for 27 V to 38 V dc input voltage, 230 V rms ac output voltage, and rated for line cycle average power of 70 W, has been built and tested in grid-connected mode. It is shown that the MEB can successfully enhance the performance of a single-phase grid-interfaced micro-inverter by increasing its efficiency and reducing the total size of the twice-line-frequency energy buffering capacitance. 2014-10-02T17:11:03Z 2014-10-02T17:11:03Z 2013-09 Article http://purl.org/eprint/type/ConferencePaper 978-1-4799-0336-8 http://hdl.handle.net/1721.1/90544 Chen, Minjie, Khurram K. Afridi, and David J. Perreault. “A Multilevel Energy Buffer and Voltage Modulator for Grid-Interfaced Micro-Inverters.” 2013 IEEE Energy Conversion Congress and Exposition (September 2013). https://orcid.org/0000-0003-0705-563X https://orcid.org/0000-0002-0746-6191 en_US http://dx.doi.org/10.1109/ECCE.2013.6647102 Proceedings of the 2013 IEEE Energy Conversion Congress and Exposition Creative Commons Attribution-Noncommercial-Share Alike http://creativecommons.org/licenses/by-nc-sa/4.0/ application/pdf Institute of Electrical and Electronics Engineers (IEEE) MIT web domain
spellingShingle Chen, Minjie
Perreault, David J.
Afridi, Khurram
A multilevel energy buffer and voltage modulator for grid-interfaced micro-inverters
title A multilevel energy buffer and voltage modulator for grid-interfaced micro-inverters
title_full A multilevel energy buffer and voltage modulator for grid-interfaced micro-inverters
title_fullStr A multilevel energy buffer and voltage modulator for grid-interfaced micro-inverters
title_full_unstemmed A multilevel energy buffer and voltage modulator for grid-interfaced micro-inverters
title_short A multilevel energy buffer and voltage modulator for grid-interfaced micro-inverters
title_sort multilevel energy buffer and voltage modulator for grid interfaced micro inverters
url http://hdl.handle.net/1721.1/90544
https://orcid.org/0000-0003-0705-563X
https://orcid.org/0000-0002-0746-6191
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