segunda-feira, 30 de outubro de 2023
Isolated DC-DC Power Converters for Simultaneous Charging of Electric Vehicle Batteries: Research Review, Design, High-Frequency Transformer Testing, Power Quality Concerns, and Future-----Srinath Belakavadi Sudarshan and Gopal Arunkumar
Abstract:
The transportation industry is transitioning from conventional Internal Combustion Engine
Vehicles (ICVs) to Electric Vehicles (EVs) due to the depletion of fossil fuels and the rise in nontraditional
energy sources. EVs are emerging as the new leaders in the industry. Some essential
requirements necessary for the widespread adoption of EVs include sufficient charging stations with
numerous chargers, less to no wait time before charging, quick charging, and better range. To enable
a quicker transition from ICVs to EVs, commercial organizations and governments would have to put
in a mammoth effort, given the low number of installed chargers in developing nations such as India.
One solution to lower the waiting time is to have multiple vehicles charging simultaneously, which
might involve charging two- and four-wheelers simultaneously, even though their battery voltage
ratings differ. This paper begins by providing the details of the power sources for EV charging,
the charging levels and connector types, along with the specifications of some of the commercial
chargers. The necessity of AC-DC converters in EV charging systems is addressed along with the
power quality concerns due to the increased penetration of EVs. Next, a review of the existing
research and technology of isolated DC-DC converters for simultaneous charging of EV batteries is
provided. Further, several potential isolated DC-DC converter topologies for simultaneous charging
are described with their design and loss estimation. A summary of the existing products and
projects with simultaneous charging features is provided. Finally, insight is given into the future of
simultaneous charging.
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domingo, 29 de outubro de 2023
Técnicas de control para la conexión en paralelo de inversores aplicadas a convertidores de interconexión entre los buses de CC y CA de microrredes híbridas e inversores fotovoltaicos centralizados de alta potencia---DEPARTAMENTO DE INGENIERÍA ELECTRÓNICA Grupo de Sistemas Electrónicos Industriales
Técnicas de control para la conexión en paralelo de inversores aplicadas a convertidores de interconexión entre los buses de CC y CA de microrredes híbridas e inversores fotovoltaicos centralizados de alta potencia-
DEPARTAMENTO DE INGENIERÍA ELECTRÓNICA Grupo de Sistemas Electrónicos Industriales
Tesis Doctoral
Presentada por:
Marian Liberos Mascarell
Dirigida por:
Dr. Emilio Figueres Amorós
Dr. Gabriel Garcerá Sanfelíu
Valencia, Abril 2021 UNIVERSIDAD POLITECNICA DE VALENCIA
Resumen
En este trabajo se proponen técnicas de control específicas para la paralelización de inversores sin transformador conectados a red, en aplicaciones de interconexión de buses de microrredes híbridas e instalaciones fotovoltaicas de gran potencia. La paralelización de inversores presenta múltiples ventajas como la modularidad, la redundancia o la flexibilidad para ampliar la potencia de un sistema o de una instalación. En el caso de inversores fotovoltaicos centralizados, también permite la conexión/desconexión de módulos inversores conectados en paralelo permitiendo una mayor eficiencia global cuando se trabaja a bajas potencias. Sin embargo, la paralelización de inversores provoca la aparición de corrientes de circulación que pueden provocar efectos indeseables en el sistema o en la instalación.
Las contribuciones que se llevan a cabo en esta tesis están todas ellas orientadas a la mejora de la operación de inversores en paralelo en las aplicaciones descritas y son las siguientes:
1) Se presenta un modelo preciso en pequeña señal de n inversores conectados en paralelo con filtro de conexión a red LCL, en el cual se tienen en consideración los términos de acoplamiento entre fases de los inductores trifásicos.
2) Se propone una técnica de control en la que se emplean n-1 lazos de regulación que controlan la componente homopolar de las corrientes e imponen un valor nulo en régimen permanente, a fin de eliminar las corrientes de circulación.
3) Se propone el uso de moduladores en espacio vectorial de tres dimensiones (3D-SVM) para implementar el control de la componente homopolar de las corrientes.
4) Se muestran resultados analíticos, de simulación y experimentales que validan el esquema de control propuesto considerando la aparición de corrientes de circulación debido a distintos factores: desbalanceo de inductancias entre las fases de un inversor y de distintos inversores, desbalanceo de potencia entre inversores y empleo de modulaciones distintas en los inversores conectados en paralelo. Los ensayos experimentales se realizan sobre un convertidor trifásico de 10 kW formado por la conexión en paralelo de dos módulos de 5 kW cada uno.
5) Se muestran resultados de simulación y experimentales de la aplicación de las técnicas de reducción de corrientes de circulación a convertidores de interconexión entre los buses de alterna y continua de microrredes híbridas. Los ensayos experimentales se particularizan a un convertidor trifásico de 7.5 kW formado por un módulo de 5 kW y otro de 2.5 kW conectados en paralelo, emulando una eventual ampliación de potencia del 50 %.
6) Se lleva a cabo el estudio por simulación de un sistema fotovoltaico de 2 MW compuesto por cuatro inversores de 500 kW conectados en paralelo, demostrando que el control de las componentes homopolares de las corrientes reduce en gran medida el valor de las corrientes de circulación y mejora el desempeño de la instalación.
7) Por último, se propone una técnica de control para mejorar la eficiencia global de inversores fotovoltaicos centralizados de potencia elevada, el cual se basa en la utilización de modelos funcionales bidimensionales de eficiencia para activar/desactivar los módulos de potencia en función del punto de operación del campo fotovoltaico.
Abstract
In this work they have been proposed specific control techniques for the parallelization of transformerless inverters connected to the grid in two specific applications: i) the interlinking converter between ac and dc bus of hybrid microgrids and ii) high power photovoltaic farms. Paralleling of inverters presents some advantages as modularity, redundancy or flexibility for increasing the power of a system or of a plant. In photovoltaic centralized inverters, the parallel inverters can be connected and disconnected in order to improve the global efficiency when the system works at low power. However, the inverters paralleling causes the appearance of circulating currents which can produce undesirable effects in the system or in the plant.
The contributions that are carried out in this thesis are all of them aimed at improving the operation of parallel inverters in the described applications and they are as follows:
1) It has been presented an accurate small signal model of n parallel inverters with an LCL grid filter, in which the mutual coupling terms of the three-phase inductors has been considered.
2) It has been proposed a control technique with n-1 control loops that control the zero-sequence current component by setting a zero value in steady state, looking for eliminating the circulating currents.
3) It has been proposed the use of three-dimension space vector modulator (3D-SVM) to implement the zero-sequence currents control.
4) The analytical results have been validated by means of simulation and experimental results, showing the performance of the proposed control scheme considering the appearance of circulating currents due to different factors: i) inductor imbalances between the phases of an inverter or ii) between different inverters, iii) power imbalances between inverters and iv) the use of different modulation techniques in the parallel inverters. The experimental tests have been carried out on a 10 kW three-phase converter composed by the parallel connection of two 5 kW modules.
5) They have been shown both simulation and experimental results of the application of circulating current reduction techniques to interlinking converters between the DC and the AC buses of hybrid microgrids. The experimental tests have been particularized to a 7.5 kW three-phase converter
composed by a 5 kW and a 2.5 kW module connected in parallel, emulating an eventual 50 % power expansion.
6) Is has been carried out the simulation study of a 2 MW photovoltaic system composed by four 500 kW inverters connected in parallel, showing that the control of the zero-sequence currents greatly reduces the value of the circulating currents and improve the system performance.
7) Finally, it has been proposed a control technique for the improvement of the global efficiency of high power photovoltaic centralized inverters, which is based in the use of bidimensional functional efficiency models to activate/deactivate the power modules according to the operation point of the photovoltaic farm.VIEW FULL TEXT:https://riunet.upv.es/handle/10251/168190
sexta-feira, 27 de outubro de 2023
Ebook: Inversores Fotovoltaicos conectados à rede-ENSAIOS E DESENVOLVIMENTO DE SISTEMAS FOTOVOLTAICOS PARA APOIO AO SETOR DE ENERGIAS RENOVÁVEIS DO RS, aprovado no Edital 01/2016 – Programa de Apoio aos Pólos Tecnológicos da Secretaria de Desenvolvimento Econômico, Ciência e Tecnologia do Estado do Rio Grande do Sul (SDECT/RS)
VIEW FULL TEXT: https://inriufsm.com.br/wp-content/uploads/2023/06/Cartilha_virtual-_Ensaio_Inversores_Fotovoltaicos.pdf
Essa cartilha virtual é resultado do projeto ENSAIOS E DESENVOLVIMENTO DE SISTEMAS FOTOVOLTAICOS PARA APOIO AO SETOR DE ENERGIAS RENOVÁVEIS DO RS, aprovado no Edital 01/2016 – Programa de Apoio aos Pólos Tecnológicos da Secretaria de Desenvolvimento Econômico, Ciência e Tecnologia do Estado do Rio Grande do Sul (SDECT/RS), Convênio DCIT 62/2016. Autores:
Prof. Leandro Michels – UFSM (organizador) Prof. Lucas Vizzotto Bellinaso – UFSM
Henrique Horst Figueira – UFSM
Ricardo Jochann Franceschi Bortolini – UFSM
Débora de Moura Steinhorst – UFSM
Alexandre Torres Ruschel – UFSM
Lucas Gais Gularte – UFSM
Alisson Mazzorani Vieira – UFSM
Igor Antônio Baldissera de Bitencourt – UFSM
Mateus Nava Mezaroba – URI/Erechim
Equipe do projeto:
Prof. Dr. Leandro Michels (coordenador) – UFSM
Prof. Dr. José Renes Pinheiro (pesquisador) – UFSM
Prof. Dr. Hélio Leães Hey (pesquisador) – UFSM
Prof. Dr. Cassiano Rech (pesquisador) – UFSM
Prof. Dr. Cassiano Rech (pesquisador) – UFSM
Prof. Dr. Julio Cezar Mairesse Siluk (pesquisador) – UFSM
Prof. Dr. Luciano Schuch (pesquisador) – UFSM
Prof. Dra. Morgana Pizzolato (pesquisadora) – UFSM
Prof. Dr. Jorge Rodrigo Massing (pesquisador) – UFSM
Prof. Dr. Elpidio Oscar Benitez Nara (pesquisador) – UNISC
Apoio:
Sonnen Energia Ltda - EPP
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