2,843 research outputs found
Model predictive control applied to an improved five-level bidirectional converter
This paper presents an improved five level bidirectional converter (iFBC) controlled by finite control set model predictive control (FCS-MPC). This control strategy consists in using the discrete time nature of the iFBC to define its state in each sampling interval. Using FCS-MPC the switching frequency is not constant; however, it is suitable to follow the current reference with low total harmonic distortion (THD). The iFBC prototype that was specially developed for obtaining experimental results is described in detail along the paper, as well as its principle of operation, power theory, and current control strategy. The iFBC was experimentally validated connected to the power grid through a second order LfCf passive filter, operating as an active rectifier and as a grid tie inverter. For both operation modes, the experimental results confirm the good performance (in terms of efficiency, low current THD and controlled output voltage) of the iFBC controlled by FCS-MPC.FC
Model predictive current control of a proposed single-switch three-level active rectifier applied to EV battery chargers
This paper presents a model predictive current
control applied to a proposed new topology of single-switch
three-level (SSTL) active rectifier, which is exemplified in an
application of single-phase battery charger for electric vehicles
(EVs). During each sampling period, this current control scheme
selects the state of the SSTL active rectifier that minimizes the
error between the grid current and its reference. Using this
strategy it is possible to obtain sinusoidal grid currents with low
total harmonic distortion and unitary power factor, which is one
of the main requirements for EVs chargers. The paper presents
in detail the principle of operation of the SSTL active rectifier,
the digital control algorithm and the EV battery charger (where
is incorporated the SSTL active rectifier) that was used in the
experimental verification. The obtained experimental results
confirm the correct application of the model predictive current
control applied to the proposed SSTL active rectifier.This work was supported in part by the FCT–Fundação para a Ciência e Tecnologia in the scope of the project: PEst UID/CEC/00319/2013. VÃtor Monteiro was supported by the scholarship SFRH/BD/80155/2011 granted by the FCT agency
A novel single-phase bidirectional nine-level converter employing four quadrant switches
A novel bidirectional ac-dc multilevel converter
based on four quadrant switches is proposed. This new
converter can establish nine voltage levels downstream the
coupling filter used to interface with the power grid, and,
comparing with conventional two- or three-level converters, it
operates with improved ac-side current, both for operation as
active rectifier (on-grid), grid-tied inverter (on-grid) or voltage
inverter (off-grid). A detailed description of the converter is
exhibited, highlighting its main advantages according to the
applications where it can be employed in smart grid scenarios.
In order to confirm its viability, a considerable set of results is
presented and discussed, establishing an overall comparison
with conventional converters. Moreover, the proposed
converter is validated operating as active rectifier, as grid-tied
inverter, and as voltage inverter, controlled in closed-loop by
current or voltage. The details of the proposed power converter
hardware and the implementation of the digital algorithm,
based on a fixed switching frequency structure, are clarified and
discussed throughout the paper.This work has been supported by COMPETE: POCI-010145-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 within project SAICTPAC/0004/2015 – POCI – 01–0145–FEDER–016434. Mr. Tiago Sousa is supported by the doctoral scholarship SFRH/BD/134353/2017 granted by of the FCT project 0302836 NORTE-01-0145-FEDER-030283.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
Novel single-phase five-level VIENNA-type rectifier with model predictive current control
A novel single-phase five-level active rectifier based
on the VIENNA-type rectifier with model predictive current
control is presented. The proposed topology operates in
unidirectional mode, imposing a sinusoidal grid-side current with
unitary power factor. A unidirectional electric vehicle battery
charger is the target application in which the proposed rectifier is
used; however, it can also be used as an active rectifier for other
purposes aiming to improve the efficiency of ac-to-dc
rectification. The model predictive current control is used to
select the active rectifier state during each sampling period,
trying to minimize the grid current error and obtain low total
harmonic distortion. The suitability and performance of the
proposed topology of active rectifier, as well as the principle of
operation and the digital control algorithm, are evaluated
through simulation and 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
Power Quality Enhancement in Hybrid Photovoltaic-Battery System based on three–Level Inverter associated with DC bus Voltage Control
This modest paper presents a study on the energy quality produced by a hybrid system consisting of a Photovoltaic (PV) power source connected to a battery. A three-level inverter was used in the system studied for the purpose of improving the quality of energy injected into the grid and decreasing the Total Harmonic Distortion (THD). A Maximum Power Point Tracking (MPPT) algorithm based on a Fuzzy Logic Controller (FLC) is used for the purpose of ensuring optimal production of photovoltaic energy. In addition, another FLC controller is used to ensure DC bus stabilization. The considered system was implemented in the Matlab /SimPowerSystems environment. The results show the effectiveness of the proposed inverter at three levels in improving the quality of energy injected from the system into the grid.Peer reviewedFinal Published versio
A novel fixed switching frequency control strategy applied to an improved five-level active rectifier
A novel fixed switching frequency control
strategy applied to an improved five-level active rectifier
(iFLAR) is proposed. The operation with fixed switching
frequency represents a powerful advantage, since the range of
the produced harmonics is well identified, and it is possible to
design passive filters to mitigate such harmonics. The
experimental validation shows that the control strategy allows
attaining an ac-side current with reduced total harmonic
distortion and high power factor, which is an attractive
influence for grid-connected electrical appliances. This
contribution is even more relevant with the new paradigm of
smart grids where higher levels of power quality are required.
A theoretical analysis of the control strategy and the details of
its implementation in a digital signal processor are presented.
The control scheme and the developed iFLAR were
experimentally confirmed using a laboratorial prototype,
showing its benefits in terms of accuracy, reduced total
harmonic distortion and high power factor.This work has been supported by COMPETE: POCI-010145-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. Mr. Tiago Sousa is supported by the doctoral scholarship SFRH/BD/134353/2017 granted by the Portuguese FCT agency. This work is part of the FCT project 0302836 NORTE-01-0145-FEDER-030283.info:eu-repo/semantics/publishedVersio
Comprehensive analysis and experimental validation of five-level converters for ev battery chargers framed in smart grids
The electric vehicle (EV) is the foremost element for spreading electric mobility in smart grids. Its integration into the electrical power grid involves the use of battery chargers with improved power quality aspects, and therefore, the topology of the front-end power converter represents a vital role in the EV battery charger (EVBC). Since multilevel topologies offer a set of advantages to accomplish with the power grid interface, a comprehensive investigation of two five-level topologies for EVBCs is presented in this paper. An accurate computational validation and a meticulous explanation of the hardware and software required for the five-level topologies under study is presented and explained considering realistic operating conditions. The obtained results show the pros and cons of each topology targeting EVBC applications for smart grids.This work has been supported by FCT – Fundação para a Ciência e Tecnologia within the Project Scope: UID/CEC/00319/2019. This work has been supported by FCT Project newERA4GRIDs – New Generation of Unified Power Conditioner with Advanced Control, Integrating Electric Mobility, Renewables, and Active Filtering Capabilities for the Power Grid Improvement: POCI-01-0145-FEDER-030283. Mr. Tiago Sousa is supported by the doctoral scholarship SFRH/BD/134353/2017 granted by the Portuguese FCT agency
Model predictive control applied to a single phase seven-level active rectifier
© 2017 IEEE. This paper presents an improved single phase seven-level active rectifier architecture controlled by finite control set model predictive control (FCS-MPC). The FCS-MPC is designed to enable power conversion with a unity power factor and generate seven level voltage waveform at the input. The proposed active rectifier architecture reduces harmonic contents of the rectifier input current by producing different voltage levels at the rectifier input. Owing to the architecture and multilevel operation, it reduces the EMI filter size, input current harmonic, the voltage rating on devices and switching losses that are lower than those of conventional three-level rectifier topologies. The proposed converter can also be operated as a multilevel inverter. Extensive simulation results are presented to verify the proposed converter when the load changes, the reference active and reactive power changes
Solid state transformer technologies and applications: a bibliographical survey
This paper presents a bibliographical survey of the work carried out to date on the solid state transformer (SST). The paper provides a list of references that cover most work related to this device and a short discussion about several aspects. The sections of the paper are respectively dedicated to summarize configurations and control strategies for each SST stage, the work carried out for optimizing the design of high-frequency transformers that could adequately work in the isolation stage of a SST, the efficiency of this device, the various modelling approaches and simulation tools used to analyze the performance of a SST (working a component of a microgrid, a distribution system or just in a standalone scenario), and the potential applications that this device is offering as a component of a power grid, a smart house, or a traction system.Peer ReviewedPostprint (published version
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