A Methodology to Estimate Real-world Vehicle Fuel Use and Emissions based on Certification Cycle Data

AbstractThis work presents a methodology to estimate vehicle fuel consumption and NOx mass emission rates using only public certification data from individual vehicles. Using on-road data collected from 14 vehicles it was possible to establish trends of fuel use and emissions according with the power demand, using the Vehicle Specific Power methodology, which were further applied to estimate modal fuel consumption and NOx emission rates on Diesel vehicles. Comparing with real-world operation, fuel consumption estimates presented average absolute deviations lower than 10%. Regarding NOx estimates, average absolute deviation is around 22%. With this method it is possible to evaluate an individual vehicle using public data without have to measure it on-road and establishing links between certification and real-world vehicle operation

A novel topology of modular multilevel bidirectional non-isolated dc-dc converter

The paradigm of smart grids has been continuously addressing new challenges in terms of power electronics converters, for instance, to deal with technologies like renewables, electric mobility, energy storage, and hybrid power grids. Allied with this context, a novel topology of modular multilevel bidirectional (MMB) non-isolated dc-dc converter is proposed in this paper. Taking into consideration the nature of the proposed MMB dc-dc converter, it is appropriated to operate as back-end converter linked to front-end ac-dc converters based on cascade structures, i.e., with more than one dc-link. As distinctive features, the proposed MMB dc-dc converter can operate with five-voltage levels, allowing to reduce the voltage stress in each semiconductor, and it is controlled based on the interleaved principle of operation, although it is not an interleaved converter. A dedicated pulse-width modulation, as well as voltage and current control strategies, are proposed and clearly explained along the paper. The claimed distinctive features of the proposed MMB dc-dc converter are supported by analytic description and by computer simulation validation, considering steady-state and transient-state operations in relevant conditions of the dc interfaces.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/EEI-EEE/30382/2017. Tiago Sousa is supported by the doctoral scholarship SFRH/BD/134353/2017 granted by FCT

Impacts of On-board Devices and Training on Light Duty Vehicle Driving Behavior

AbstractThe main objective of this investigation was to assess the impacts of an eco-driving education session on the energy and environmental performance of a group of drivers as well as changes on their driving patterns. Driving behavior was assessed with an on-board monitoring device, the CarChip Pro. This on-board data logger allowed the characterization of driving patterns, collecting data regarding driving parameters - such as speed and acceleration - and engine parameters. Potential savings in fuel consumption and reduction of CO2 and NOx emissions were assessed based on the VSP “Vehicle Specific Power” methodology.A sample of 20 drivers was monitored in two distinct periods. Two groups were defined. A group of 9 drivers received at the end of the first monitoring period, an eco-driving educational session, where information regarding which conducts should be adopted in order to assume a more ecological driving behavior was shared as well as insight concerning their driving performance was given. The remaining drivers received no information. A total of 1364 days and 1928hours of driving were monitored, corresponding to 8137 trips and 100212km travelled. The results show that, after the eco-driving education session, drivers decreased the time spent in excessive speed and excessive engine speed by 24% and 38% respectively. A reduction in the number of events such as extreme accelerations and decelerations was also observed. The results indicate an average 4.8% fuel consumption decrease, corresponding to savings of 0.09MJ/km and 6.56g/km of CO2 emissions in the Tank-To-Wheel stage. Concerning NOx emissions a decrease of 8% was observed for this experimental group

Vulnerability assessment of real water distribution networks using the TV-WPN informatics tool

The design, operation and rehabilitation of water supply systems must have an asset management strategy, addressing hydraulic, technical, economic, social, environmental, and health issues with a high level of complexity. The vulnerability assessment and the resilience increment of a water distribution networks can be supported by the emerging Theory of Vulnerability of Water Pipe Networks (TV-WPN), which allows to systematize failure scenarios and map the major disproportions between failure consequences and the initial damage. Failure scenarios are defined leading simultaneously with hydraulic capacity deterioration and structural integrity, the main issues of water networks safety. The manual application of TV-WPN is almost impossible to be used in real-world water networks. So, it was initially tested using only simple theoretical networks, needing a new and more expeditious tool (like an automatic computation program) that could encourage its use by designers and managers of this type of hydraulic infrastructure. The recent development of the TV-WPN software tool allowed to speed up the calculation process, enabling the application of this theory to real water supply networks. This work presents the application of tool to a real water distribution network located in a village of Braga municipality for analyze their hydraulic performance and vulnerability, as well as to check and evaluate TV-WPN performance in a real-world case. It was concluded that the frequent presence of pipelines with very low flow velocities (due to the imposition of regulatory minimum diameters) can compromise the successful application of this software to real water distribution networks, namely in rural areas where flow rates are generally lower. However it is also an opportunity for future developments

A review on integrated battery chargers for electric vehicles

Electric vehicles (EVs) contain two main power electronics systems, namely, the traction system and the battery charging system, which are not used simultaneously since traction occurs when the EV is travelling and battery charging when the EV is parked. By taking advantage of this interchangeability, a single set of power converters that can perform the functions of both traction and battery charging can be assembled, classified in the literature as integrated battery chargers (IBCs). Several IBC topologies have been proposed in the literature, and the aim of this paper is to present a literature review of IBCs for EVs. In order to better organize the information presented in this paper, the analyzed topologies are divided into classical IBCs, IBCs for switched reluctance machines (SRMs), IBCs with galvanic isolation, IBCs based on multiple traction converters and IBCs based on multiphase machines. A comparison between all these IBCs is subsequently presented, based on both requirements and possible functionalities.This work has been supported by FCT - Fundação para a Ciência e Tecnologia within the R&D Units Project Scope: UIDB/00319/2020. T.J.C.S. is supported by the FCT scholarships SFRH/BD/134353/2017 and COVID/BD/151993/2021

Model predictive control of a single-phase five-level VIENNA rectifier

Power converters and control strategies are very vital for the increasing sustainability of the power grid targeting smart grids. In these circumstances, it is proposed a novel single-phase five-level (SP5L) VIENNA rectifier digitally controlled by a model predictive control (MPC) with fixed switching frequency, which can be useful for a variety of applications with a robust current tracking. The proposed SP5L VIENNA rectifier is an advancement of the classical three-level VIENNA rectifier, also contributing to preserve power quality, and exhibiting the advantage of operating with more voltage levels at the expense of few additional switching devices. The proposed topology is introduced and correlated with the classical solutions of active rectifiers. The operation principle is introduced and used to describe the MPC, which is given in detail, as well as the necessary modulation strategy. The results were obtained for a set of various operating conditions, both in terms of reference of current and grid-side voltage, as well as in steady-state and transient-state, proving the benefits of the proposed SP5L VIENNA rectifier and the accurate and precise use of the MPC to control the grid-side current.This work has been supported by FCT -Fundacao para a Ciencia 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/EEI-EEE/30382/2017. Tiago Sousa is supported by the doctoral scholarship SFRH/BD/134353/2017 granted by FCT

A Three-Level dc-dc Converter for Bipolar dc Power Grids: Analysis and Experimental Validation

The concept of bipolar dc power grids has emerged, mainly due to the improvements in efficiency and offered flexibility when compared with unipolar architectures. Though, concerns of asymmetrical loads affecting voltage unbalances is the key challenge to overcome. In this context, power electronics play an important influence since the features of the topology contribute to define the quality of the bipolar dc power grids. This paper presents the application of a bipolar bidirectional three-level (BB3L) dc dc converter as a contribution to mitigate the aforementioned concern of bipolar dc power grids. The proposed BB3L dc-dc converter is introduced, and an insightful description of its principle of operation is presented throughout the paper. Since the BB3L dc dc converter operates with three voltage levels, it is possible to diminish the blocking voltage of the switching devices, representing an important feature of such topology. Additionally, it can operate with the voltage and current variables controlled with the double of the switching frequency, also representing an added value of such topology. The distinct possibilities of operation are presented, both in buck mode and boost mode, and an experimental validation is presented to validate the main features of the BB3L dc dc converter for bipolar dc power grids.INCT-EN -Instituto Nacional de Ciência e Tecnologia para Excitotoxicidade e Neuroproteção (UID/CEC/00319/2020

Interfacing power electronics systems for smart grids: innovative perspectives of unified systems and operation modes

The power distribution grid is centrally managed concerning the requirements of the end-users, however, with the appearance of smart grids, new technologies arc arising. Therefore, distributed energy resources, mainly, renewables, energy storage systems, electric mobility, and power quality are viewed as encouraging contributions for improving power management. In these circumstances, this paper presents a power electronics perspective for the power distribution grid, considering innovative features, and including a power quality perception. Throughout the paper are presented relevant concepts for a concrete realization of a smart grid, supported by the integration of power electronics devices as the interface of the mentioned technologies. Aiming to support the innovative power electronics systems for interfacing the mentioned technologies in smart grids, a set of developed power electronics equipment was developed and, along with the paper, are shown and described, supporting the most important contributions of this paper.This work has been supported by FCT -Fundação para a Ciencia 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

Performance comparison of a typical nonlinear load connected to Ac and Dc power grids

This paper presents a performance comparison of a typical nonlinear load used in domestic appliances (electronic load), when supplied by an ac and a dc voltage of the same rms value. The performance of the nonlinear load towards its connection to ac and dc power grids is accomplished in terms of the waveforms which are registered in the consumed current, internal dc-link voltage and output voltage. A simulation model was developed using realistic database models of the power semiconductors comprising a nonlinear load with input ac-dc converter, so that the efficiency can be calculated and compared for three distinct cases: (1) load supplied by an ac voltage; (2) load supplied by a dc voltage; (3) load without the input ac-dc converter supplied by a dc voltage. Thus, besides the comparison between the ac and dc power grids supplying the same nonlinear load (cases 1 and 2), a third case is considered, which consists of removing the input ac-dc converter (eliminating needless components of the nonlinear load when supplied by a dc voltage). The obtained results show that supplying nonlinear loads with dc power grids is advantageous in relation to the ac power grid, and therefore it can be beneficial to adapt nonlinear loads to be powered by dc power grids.This work has been supported by COMPETE: POCI-01-0145–FEDER–007043 and FCT –Fundação para a Ciência eTecnologia within the Project Scope: UID/CEC/00319/2013. This work is financed by the ERDF –European Regional De-velopment Fund through the Operational Programme for Competitiveness and Interna-tionalisation –COMPETE 2020 Programme, and by National Funds through the Por-tuguese funding agency, FCT –Fundação para a Ciência e a Tecnologia,within project SAICTPAC/0004/2015 –POCI –01–0145–FEDER–016434. Mr. Tiago Sousa is sup-ported by the doctoral scholarship SFRH/BD/134353/2017 granted by the Portuguese FCT agency

Performance comparison of a typical nonlinear load supplied by ac and dc voltages

This paper presents a performance comparison of a typical nonlinear load when supplied by ac or dc voltages with the same rms value. The performance of the nonlinear load towards its connection to ac and dc power grids is accomplished in terms of the waveforms and efficiency. A simulation model was developed using realistic database models of the power semiconductors comprising the load, and an experimental setup was assembled, so that the efficiency can be determined and compared for simulation and real operating conditions. Three distinct cases were considered for this study: (1) Load supplied by ac voltage; (2) Load supplied by dc voltage; and (3) Load without the input ac-dc converter supplied by dc voltage. The obtained results show that supplying nonlinear loads with dc power grids is advantageous in relation to the ac power grid, and therefore it can be beneficial to adapt nonlinear loads to be powered by dc power grids.This work has been supported by COMPETE: POCI-01-0145–FEDER–007043 and FCT –Fundação para a Ciência e Tecnologiawithin 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 thePortuguese 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 agenc