58 research outputs found
Calibração experimental de uma câmara digital
Apresenta-se um método prático de obtenção da resposta do sensor de uma máquina fotográfica digital comum, com base numa imagem de referência produzida em qualquer loja de impressão de fotografia. O grande objectivo é poder caracterizar a qualidade da luz emitida por lâmpadas de baixo consumo sem recorrer a dispositivos especiais.Fundação para a Ciência e a Tecnologia (FCT
Experimental comparison of single-phase active rectifiers for EV battery chargers
An experimental comparison of single-phase active rectifiers for electric vehicle (EV) battery chargers is
presented and discussed. Active rectifiers are used in on-board EV battery chargers as front-end converters
to interface the power grid aiming to preserve the power quality. In this paper, four topologies of active
rectifiers are compared: traditional power-factor-correction; symmetrical bridgeless; asymmetrical
bridgeless; and full-bridge full-controlled. Such comparison is established in terms of the requirements for
the hardware structure, the complexity of the digital control system, and the power quality issues, mainly the
grid current total harmonic distortion and the power factor. Along the paper these comparisons are presented
and verified through experimental results. A reconfigurable laboratorial prototype of an on-board EV
battery charger connected to the power grid was used to obtain the experimental results.This work has been supported by COMPETE: POCI-01-0145-FEDER-007043 and FCT – Fundação para a Ciência e Tecnologia within the Project Scope: UID/CEC/00319/2013. This work is financed by the ERDF – European Regional Development Fund through the Operational Programme for Competitiveness and Internationalisation - COMPETE 2020 Programme, and by National Funds through the Portuguese funding agency, FCT - Fundação para a Ciência e a Tecnologia, within project SAICTPAC/0004/2015- POCI- 01-0145-FEDER-016434.info:eu-repo/semantics/publishedVersio
Comprehensive analysis and cost estimation of five-level bidirectional converters for electric vehicles operation in smart cities context
A comprehensive analysis, comparison and cost estimation of five-level bidirectional converters for the electric vehicle
(EV) operation in smart cities context is presented in this paper. Nowadays, five-level converters are widely used with
success to interface between the power grid and renewable energy sources, as well as, to operate as motor drivers.
Therefore, with the EV introduction into the power grids arises a new opportunity to use such five-level converters as
interface between the power grid and the EV batteries, i.e., in on-board charger applications. Moreover, considering the
future scenarios of smart grids and smart cities, the five-level bidirectional converters will be essential for the operation
modes grid-to-vehicle (G2V, charging the batteries from the power grid) and vehicle-to-grid (V2G, returning energy
from the batteries to the power grid). In this context, this paper presents an aggregation of the most important five-level
bidirectional converter topologies that can be applied for on-board EV chargers in smart cities context. Along the paper
it is presented a detailed description of the hardware and control algorithms of the five-level converters, and are also
presented and explained simulation results performed under realistic operating conditions. Finally, it is presented the
cost estimation for a real application considering the hardware requirements for each one of the converters.This work has been supported by COMPETE: POCI-01-0145-FEDER-007043 and FCT – Fundação para a Ciência e
Tecnologia within the Project Scope: UID/CEC/00319/2013 and by the ERDF – European Regional Development Fund
through the Operational Programme for Competitiveness and Internationalisation Ǧ COMPETE 2020 Programme, and
by National Funds through the Portuguese funding agency, FCT Ǧ Fundação para a Ciência e a Tecnologia, within
project SAICTPAC/0004/2015-POCI-01-0145-FEDER-016434.info:eu-repo/semantics/publishedVersio
Review of a disruptive vision of future power grids: a new path based on hybrid AC/DC grids and solid-state transformers
Power grids are evolving with the aim to guarantee sustainability and higher levels of power quality for universal access to electricity. More specifically, over the last two decades, power grids have been targeted for significant changes, including migration from centralized to decentralized paradigms as a corollary of intensive integration of novel electrical technologies and the availability of derived equipment. This paper addresses a review of a disruptive vision of future power grids, mainly focusing on the use of hybrid AC/DC grids and solid-state transformers technologies. Regarding hybrid AC/DC grids in particular, they are analyzed in detail in the context of unipolar and bipolar DC grids (i.e., two-wire or three-wire DC grids), as well as the different structures concerning coupled and decoupled AC configurations with low-frequency or high-frequency isolation. The contextualization of the possible configurations of solid-state transformers and the different configurations of hybrid transformers (in the perspective of offering benefits for increasing power quality in terms of currents or voltages) is also analyzed within the perspective of the smart transformers. Additionally, the paper also presents unified multi-port systems used to interface various technologies with hybrid AC/DC grids, which are also foreseen to play an important role in future power grids (e.g., the unified interface of renewable energy sources and energy storage systems), including an analysis concerning unified multi-port systems for AC or DC grids. Throughout the paper, these topics are presented and discussed in the context of future power grids. An exhaustive description of these technologies is made, covering the most relevant and recent structures and features that can be developed, as well as the challenges for the future power grids. Several scenarios are presented, encompassing the mentioned technologies, and unveiling a progressive evolution that culminates in the cooperative scope of such technologies for a disruptive vision of future power grids.This work has been supported by FCT—Fundação para a Ciência e Tecnologia within
the R&D Units Project Scope: UIDB/00319/2020. This work has been supported by the FCT
Project newERA4GRIDs PTDC/EEI-EEE/30283/2017, and by the FCT Project DAIPESEV PTDC/EEIEEE/30382/2017
Evaluation of the introduction of electric vehicles in the power grid – a study for the island of Maio in Cape Verde
Serie: Lecture notes in electrical engineering, vol. 402This paper presents an evaluation of the introduction of electric vehi-cles (EVs) in an electrical power grid. The main contribution is the control analysis of the power quality considering simultaneous battery charging pro-cesses. The methodology used can be applied to any known power grid; howev-er, it was considered the case of the island of Maio, in Cape Verde, in continua-tion of previous works concerning that power grid. Two commercial different types of battery chargers were considered: a traditional model with highly dis-torted current consumption (that causes distortion in the power grid voltage), and another with almost sinusoidal current consumption. Considering simulta-neous battery charging processes, it can be concluded that the power grid struc-ture (composed by three medium voltage branches) with the current power de-mands of the consumers of the island of Maio have a potential integration for 300 EVs if battery chargers with almost sinusoidal current consumption are used, i.e., 152 for the first medium voltage branch, 35 for the second branch, and 113 for the third branch. Moreover, the results show that the first medium voltage branch of the distribution system, which has the capability to support the integration of 152 EVs if the battery chargers have sinusoidal current con-sumption (presenting a maximum value of THDv% in the power grid voltage of 1.8%), only can support 27 EVs if are used traditional battery chargers, with highly distorted current consumption (considering a maximum THDv% of 5%).COMPETE: POCI-01-0145-FEDER-007043Fundação para a Ciência e Tecnologia (FCT) - UID/CEC/00319/2013Fundação para a Ciência e Tecnologia (FCT) - SFRH/BD/80155/201
Field oriented control of an axial flux permanent magnet synchronous motor for traction solutions
Electric Vehicles (EVs) are increasingly used
nowadays, and different powertrain solutions can be adopted. This
paper describes the control system of an axial flux Permanent
Magnet Synchronous Motor (PMSM) for EVs powertrain. It is
described the implemented Field Oriented Control (FOC)
algorithm and the Space Vector Modulation (SVM) technique.
Also, the mathematical model of the PMSM is presented. Both,
simulation and experimental, results with different types of
mechanical load are presented. The experimental results were
obtained using a laboratory test bench. The obtained results are
discussed.F CT – Fundação para a Ciência e Tecnologia in the scope of the project: PEst - OE/EEI/UI0319/201
Model predictive control of an on-board fast battery charger for electric mobility applications
Under the necessities of reducing emissions and air pollution, and also for increasing fuel economy, automotive companies have been developing electric and plug-in hybrid electric vehicles. Since these vehicles are parked when the batteries are being charged, it is possible to use the traction power converter as on-board charger, also allowing to reduce weight, volume and costs of components in the vehicle. In this context, this paper presents a model predictive control algorithm for an on-board fast battery charging that uses the traction power converter of an electric vehicle. Simulation results and system implementation are depicted, and finally, are presented some experimental results obtained with the proposed control system.(undefined)info:eu-repo/semantics/publishedVersio
New opportunities and perspectives for the electric vehicle operation in smart grids and smart homes scenarios
New perspectives for the electric vehicle (EV) operation in smart grids and smart homes context are
presented. Nowadays, plugged-in EVs are equipped with on-board battery chargers just to perform the
charging process from the electrical power grid (G2V – grid-to-vehicle mode). Although this is the main
goal of such battery chargers, maintaining the main hardware structure and changing the digital control
algorithm, the on-board battery chargers can also be used to perform additional operation modes. Such
operation modes are related with returning energy from the batteries to the power grid (V2G- vehicle-to-grid
mode), constraints of the electrical installation where the EV is plugged-in (iG2V – improved grid-tovehicle
mode), interface of renewables, and contributions to improve the power quality in the electrical
installation. Besides the contributions of the EV to reduce oil consumption and greenhouse gas emissions
associated to the transportation sector, through these additional operation modes, the EV also represents an
important contribution for the smart grids and smart homes paradigms. Experimental results introducing the
EV through the aforementioned interfaces and operation modes are presented. An on-board EV battery
charger prototype was used connected to the power grid for a maximum power of 3.6 kW.This work has been supported by COMPETE: POCI-01-0145-FEDER-007043 and FCT – Fundação para a Ciência e Tecnologia within the Project Scope: UID/CEC/00319/2013. This work is financed by the ERDF – European Regional Development Fund through the Operational Programme for Competitiveness and Internationalisation Ǧ COMPETE 2020 Programme, and by National Funds through the Portuguese funding agency, FCT - Fundação para a Ciência e a Tecnologia, within project SAICTPAC/0004/2015- POCI- 01-0145-FEDER-016434.info:eu-repo/semantics/publishedVersio
A novel architecture of a bidirectional bridgeless interleaved converter for EV battery chargers
This paper presents a novel architecture of a
bidirectional bridgeless interleaved converter for battery
chargers of electric vehicles (EVs). The proposed converter is
composed by two power stages: an ac-dc converter that is used to
interface the power grid and the dc-link, and a dc-dc converter
that is used to interface the dc-link and the batteries. The ac-dc
converter is an interleaved bridgeless bidirectional boost-type
converter and the dc-dc converter is a bidirectional
buck-boost-type converter. The proposed converter works with
sinusoidal grid current and with high power factor for all
operating power levels, and in both grid-to-vehicle (G2V) and
vehicle-to-grid (V2G) operation modes. In the paper is described
in detail the proposed converter for EV battery chargers: the
circuit topology, the principle of operation, the power control
theory, and the current control strategy. Several simulation
results for both G2V and V2G operation modes are presented.Fundação para a Ciência e Tecnologia (FCT
Model predictive control of an on-board fast battery charger for electric mobility applications
Under the necessities of reducing emissions and air pollution, and also for increasing fuel economy, automotive companies have been developing electric and plug-in hybrid electric vehicles. Since these vehicles are parked when the batteries are being charged, it is possible to use the traction power converter as on-board charger, also allowing to reduce weight, volume and costs of components in the vehicle. In this context, this paper presents a model predictive control algorithm for an on-board fast battery charging that uses the traction power converter of an electric vehicle. Simulation results and system implementation are depicted, and finally, are presented some experimental results obtained with the proposed control system.(undefined)info:eu-repo/semantics/publishedVersio
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