On-board electric vehicle battery charger with enhanced V2H operation mode

This paper proposes an on-board Electric Vehicle (EV) battery charger with enhanced Vehicle-to-Home (V2H) operation mode. For such purpose was adapted an on-board bidirectional battery charger prototype to allow the Grid-to-Vehicle (G2V), Vehicle-to-Grid (V2G) and V2H operation modes. Along the paper are presented the hardware topology and the control algorithms of this battery charger. The idea underlying to this paper is the operation of the on-board bidirectional battery charger as an energy backup system when occurs a power outages. For detecting the power outage were compared two strategies, one based on the half-cycle rms calculation of the power grid voltage, and another in the determination of the rms value based in a Kalman filter. The experimental results were obtained considering the on-board EV battery charger under the G2V, V2G, and V2H operation modes. The results show that the power outage detection is faster using a Kalman filter, up to 90% than the other strategy. This also enables a faster transition between operation modes when a power outage occurs.Fundação para a Ciência e Tecnologia (FCT), Project Scope: Pest OE/EEI/UI0319/20

The optimization of electric buses in Iskandar Malaysia

The public transport sector has a significant share of global CO2 emission due to combustion of fossil fuel that could be catastrophic to the environment. Hence, evidence suggests that the implementation of battery electric buses (BEB) is necessary in order to reduce climate change and other environmental impacts. However, it raises a concern to bus operators regarding the conversion to BEB. This is because BEB have a fixed battery capacity, which have limited mileage, and the number of buses required to replace conventional buses due to limited charging stations available. In order to alleviate this situation, a proper fleet planning is required in order to know the amount of buses that are dispatched and the distance that the specific bus can travel. Hence, this study is conducted to optimize the cost of implementing electric buses in Iskandar Malaysia. Moreover, this study is also done to determine the optimal charging cycle that is required to cover Iskandar Malaysia and the number of buses needed to replace the existing conventional buses in order to fulfil the number of trips set by Perbadanan Pengangkutan Awam Johor (PAJ) Furthermore, a scenario analysis will be done by selecting two routes around Johor Bahru (i.e., the longest route and shortest route) with consideration of worst case scenario (i.e. high traffic) using the existing Bas Muafakat Johor’s routes, which will assist in optimizing the ideal charging cycle and number of electric buses required for each location using an optimization software called General Algebraic Modelling System (GAMS) through various scenario selection such as (a) the buses will be charged for every trip or (b) the buses will be charged after complete depletion of its battery level (i.e. 3 trips) or (c) another bus will be added for the subsequent trip. Based on the GAMS, scenario (a) and scenario (b) is both selected. This is because continuous flow of buses is required during peak hours hence suitable for scenario (b) whereas scenario (a) is much more suitable for nonpeak hours. Electric buses can save up to 132.52 kg of CO2 per trip and also saves about 536.45 kWh of energy which equivalent to 53.65 L of diesel when compared to diesel buses

Real-Time Prediction of Power Electronic Device Temperatures Using PRBS-Generated Frequency-Domain Thermal Cross Coupling Characteristics

This paper presents a technique to predict the temperature response of a multielement thermal system based on the thermal cross coupling between elements. The complex frequency-domain cross coupling of devices is first characterized using a pseudorandom binary sequence technique. The characteristics are then used to predict device temperatures for a known input power waveform using a discrete Fourier transform-based technique. The resulting prediction shows good agreement with an example practical system used for evaluation. To reduce the computational complexity of the initial method, a digital infinite impedance response (IIR) filter is fitted to each cross coupling characteristic. A high correlation fit is demonstrated that produces a near-identical temperature response compared to the initial procedure while requiring fewer mathematical operations. Experimental validation on the practical system shows good agreement between IIR filter predictions and practical results. It is further demonstrated that this agreement can be substantially improved by taking feedback from an internal reference temperature. Additionally, the proposed IIR filter technique allows the efficient calculation of future device temperatures based on simulated input, facilitating future temperature predictions

Integration of Six-Phase EV Drivetrains into Battery Charging Process with Direct Grid Connection

The paper proposes two novel topologies for integrated battery charging of electric vehicles (EVs). The integration is functional and manifests through re-utilization of existing propulsion drivetrain components, primarily a six-phase inverter and a six-phase machine, to serve as components of a fast (three-phase) charging system. An important feature of the proposed charging systems is that they are with direct grid connection, thus non-isolated from the mains. Torque is not produced in machines during the charging process. The paper provides a comprehensive evaluation of the novel systems, together with an existing topology. Various aspects of the considered chargers are detailed and elaborated, including current balancing, interleaving modulation strategy, and influence of rotor field pulsation on control and overall performance. A control strategy is proposed and the theory and control scheme are verified by experiments

A state-of-the-art review on topologies and control techniques of solid-state transformers for electric vehicle extreme fast charging

Electrical vehicle (EV) technology has gained popularity due to its higher efficiency, less maintenance, and lower dependence on fossil fuels. However, a longer charging time is a significant barrier to its complete adaptation. Solid state transformer (SST) based extreme fast charging schemes have emerged as an appealing idea with an ability to provide a refuelling capability analogous to that of gasoline vehicles. Therefore, this paper reviews the EV charger requirements, specifications, and design criteria for high power applications. At first, the key barriers of using a traditional low frequency transformer (LFT) are discussed, and potential solutions are suggested by replacing the conventional LFT with high frequency SST at extreme fast-charging (XFC) stations. Then, various SST-based converter topologies and their control for EV fast-charging stations are described. The reviewed control strategies are compared while considering several factors such as harmonics, voltage drop under varying loading conditions, dc offset load unbalances, overloads, and protection against system disturbances. Furthermore, the realization of SST for EV charging is comprehensively discussed, which facilitates understanding the current challenges, based on which potential solutions are also suggested.This publication was made possible by UREP grant # [27-021-2-010] from the Qatar National Research Fund (a member of the Qatar Foundation). The statements made herein are solely the responsibility of the authors. The Article Processing Fee of this article is paid by the Qatar National Library.Scopu

Controlo e Gestão do Carregamento de Sistemas de Armazenamento de Energia em Veículos Elétricos, Efetuado com Recurso a Conversores DC-DC

As descobertas científicas e o avanço tecnológico observados no último século e meio foram vertiginosos, superando em muito tudo o que havia sido descoberto até aos meados do século XIX. O avanço tecnológico e o desenvolvimento da sociedade moderna estão interligados, confundindo-se ao ponto de muitas dessas descobertas serem encaradas como naturais e, portanto, torna-se inconcebível imaginar a nossa existência sem essas descobertas. Mas não se pense que o insaciável apetite pelas descobertas e pela evolução se contenta com o que já foi conseguido. Tal não faz parte do espírito humano e busca-se sempre a eficiência máxima dos engenhos desenvolvidos. Essa eficiência é imposta por fatores como os próprios indivíduos, os mercados, a economia, o meio ambiente ou as necessidades energéticas. Este estudo visa investigar e desenvolver um carregador destinado a veículos elétricos, direcionado para Sistemas Elétricos de Energia (SEE) do tipo DC, de forma a dar resposta e soluções ao nível da eficiência energética, com repercussão nos restantes fatores. A maioria dos dispositivos elétricos e eletrónicos das habitações são compatíveis com a utilização de alimentação do tipo DC, o que obriga à existência de retificação de energia AC para DC. Com a implementação de SEE do tipo DC, é possível obter ganhos ao nível da eficiência energética, pela eliminação de etapas de conversão de energia. Com a mudança no paradigma da produção e consumo de energia, estão em vias de ser implementadas redes DC à escala doméstica e de bairros. Estas permitem reduzir o número de etapas de conversão de energia, bem como as perdas na distribuição dessa mesma energia. Na implementação de redes DC, será necessário criar vários níveis de tensão, que permitam a ligação de diferentes tipos de cargas à rede. A criação dos níveis de tensão adequados será feita com recurso a conversores DC-DC. No tocante aos veículos elétricos, a temática do carregamento/descarregamento de um veículo elétrico para uma micro-rede ganhou hoje uma importância acrescida, pois os veículos, para além de consumidores, podem também ser fornecedores de energia. Como o carregamento/descarregamento se processa a níveis de potência elevados, importa usar dispositivos destinados a minimizar as perdas resultantes dos processos de conversão de energia. No sentido de apurar a efetividade dos métodos aplicados, recorreu-se a um protótipo do conversor DC-DC multinível modular, para a realização dos ensaios experimentais e obtenção de resultados pretendidos.The scientific discoveries and the technological advance observed in the last century and a half were vertiginous, far exceeding everything that had been discovered until the mid-nineteenth century. The technological advancement and development of modern society are interlinked, confusing themselves to the point that many of these discoveries are regarded as natural, and therefore it becomes inconceivable to imagine our existence without these discoveries. But do not think that the insatiable appetite for discoveries and evolution is content with what has already been achieved. This is not part of the human spirit, and the maximum efficiency of the developed equipment is always sought. This efficiency is imposed by factors such as individuals themselves, markets, economics, the environment, or energetic needs. This study aims to investigate and develop a charger for electric vehicles, directed to DC Electric Energy Systems (ESS), in order to provide answers and solutions in terms of energy efficiency, with repercussion on the other factors. Most home electrical and electronic devices are compatible with the use of DC power type, which requires the existence of rectification of AC power to DC. With the implementation of DC type ESS, it is possible to achieve gains in energy efficiency by eliminating energy conversion steps. With the change in the paradigm of energy production and consumption, DC networks are being implemented at the domestic and neighborhood levels. These allow to reduce the number of stages of energy conversion, as well as losses in the distribution of that same energy. In the implementation of DC grids, it will be necessary to create several voltage levels, which allow the connection of different types of loads to the network. The appropriate voltage levels will be created using DC-DC converters. With regard to electric vehicles, the issue of charging / discharging an electric vehicle into a micro-grid has gained increasing importance today as vehicles, as well as consumers, can also be energy providers. As charging / discharging takes place at high power levels, devices designed to minimize losses resulting from power conversion processes must be used. In order to ascertain the effectiveness of the applied methods, a prototype of the modular multilevel DC-DC converter was used to carry out the experimental tests and obtain the desired results

Integrated DC-DC Charger Powertrain Converter Design for Electric Vehicles Using Wide Bandgap Semiconductors

Electric vehicles (EVs) adoption is growing due to environmental concerns, government subsidies, and cheaper battery packs. The main power electronics design challenges for next-generation EV power converters are power converter weight, volume, cost, and loss reduction. In conventional EVs, the traction boost and the onboard charger (OBC) have separate power modules, passives, and heat sinks. An integrated converter, combining and re-using some charging and powertrain components together, can reduce converter cost, volume, and weight. However, efficiency is often reduced to obtain the advantage of cost, volume, and weight reduction.An integrated converter topology is proposed to combine the functionality of the traction boost converter and isolated DC-DC converter of the OBC using a hybrid transformer where the same core is used for both converters. The reconfiguration between charging and traction operation is performed by the existing Battery Management System (BMS) contactors. The proposed converter is operated in both boost and dual active bridge (DAB) mode during traction operation. The loss mechanisms of the proposed integrated converter are modeled for different operating modes for design optimization. An aggregated drive cycle is considered for optimizing the integrated converter design parameters to reduce energy loss during traction operation, weight, and cost. By operating the integrated converter in DAB mode at light-load and boost mode at high-speed heavy-load, the traction efficiency is improved. An online mode transition algorithm is also developed to ensure stable output voltage and eliminate current oscillation during the mode transition. A high-power prototype is developed to verify the integrated converter functionality, validate the loss model, and demonstrate the online transition algorithm. An automated closed-loop controller is developed to implement the transition algorithm which can automatically make the transition between modes based on embedded efficiency mapping. The closed-loop control system also regulates the integrated converter output voltage to improve the overall traction efficiency of the integrated converter. Using the targeted design approach, the proposed integrated converter performs better in all three aspects including efficiency, weight, and cost than comparable discrete solutions for each converter

Análise Comparativa do Desempenho de Conversores DC-DC Aplicados ao Carregamento de Veículos Elétricos

O impacto ambiental da infraestrutura de transporte e o aumento do preço dos combustíveis despertaram o interesse em fontes de energias alternativas, menos poluentes e mais baratas. As preocupações com o elevado consumo de combustíveis fósseis e a crescente poluição atmosférica conduziram ao desenvolvimento dos veículos elétricos, híbridos e plug-in, mais eficientes e sustentáveis do ponto de vista ambiental. A energia elétrica consumida por estes veículos pode ser gerada por fontes de energia renováveis, que apresentam menor impacto ambiental. No actual contexto, em que a implementação de micro-redes DC assume uma posição de interesse crescente, importa responder a um conjunto de requisitos técnicos de relevo. Mais concretamente, será necessário criar vários níveis de tensão que permitam a ligação de diferentes tipos de cargas à rede. A criação dos níveis de tensão adequados será feita com recurso a conversores DCDC. Em micro-redes DC, os conversores DC-DC de alta potência consideram-se elementoschave para o carregamento/descarregamento dos VEs. Neste trabalho, duas topologias de conversores DC-DC são aplicadas ao carregamento/descarregamento de VEs, para um estudo comparativo que pretende avaliar o desempenho de cada topologia de conversor, por meio da variação de parâmetros como a potência de carregamento, a tensão de entrada, a frequência de comutação, entre outros. Os resultados obtidos a partir de uma simulação coordenada no programa Matlab|Simulink permitiram demostrar o bom funcionamento de dois sistemas propostos. As conclusões retiradas do estudo comparativo são suportadas através de resultados experimentais.The environmental impact of the transportation infrastructure, along with the increment on the price of fossil fuels, aroused interest in alternative, less polluting, and cheaper energy sources. Concerns about the high consumption of fossil fuels and the growing atmospheric pollution led to the development of electric, hybrid, and plug-in electric vehicles (EVs), considered to be more efficient and sustainable from the point of view of environment protection. The electrical energy consumed by these vehicles can be generated by renewable energy sources, which have a lower environmental impact. In the current framework, where the implementation of DC microgrids assumes a position of increasing interest, it is critical to provide solutions for a set of technical requirements of relevance. More specifically, it will be necessary to create several voltage levels that allow the connection of different types of loads to the DC microgrid. The creation of the appropriate voltage levels will be done resorting to DC-DC converters. In DC microgrids, high-power DC-DC converters are considered key elements for EV charging/discharging. In this work, two topologies of DC-DC converters are applied to the charging/discharging of EVs, aiming to carry out a comparative study that intends to evaluate the performance of each converter topology, through the variation of parameters such as the charging power, input voltage, switching frequency, among others. The results obtained from a coordinated simulation in the Matlab|Simulink software allowed to demonstrate the good operation of the two proposed systems. The conclusions taken from the comparative study are supported through experimental data

Power Conditioning for Plug-In Hybrid Electric Vehicles

Plugin Hybrid Electric Vehicles (PHEVs) propel from the electric energy stored in the batteries and gasoline stored in the fuel tank. PHEVs and Electric Vehicles (EVs) connect to external sources to charge the batteries. Moreover, PHEVs can supply stand-alone loads and inject power to the grid. Such functionalities have been defined as Vehicle to House (V2H) and Vehicle to Grid (V2G) and promoted by national and international policies such as the Energy Independency and Security Act (EISA) of 2007, enacted by the United States Congress. Exchanging energy between the vehicle and external sources is performed by the vehicular power conditioner (VPC). This dissertation proposes a design procedure for VPCs. The research mainly focuses on the VPC’s power converter design. A conceptual design approach is proposed to select the proper power converter topologies according to the determined power conditioning needs. The related standards and previous works are reviewed to determine the design guidelines. A set of specifications are introduced for a three port onboard VPC. This VPC is a reference for designs, simulations and experiments. The reference VPC is implemented with a modular three-stage isolated topology that utilizes voltage source ac-dc converters as the power conditioning stages. The multiport extension of this topology extends the vehicular power conditioning concept into a novel vehicular integrated power system. All the vehicle’s electric sources and loads can exchange energy in the described multiport integrated power system. Novel design methods are proposed for the power converter, filters, magnetic circuit and control of the VPC. The practical challenges of the VPC development are analyzed. The major contributions of this dissertation include a pioneer grounding scheme for VPC considering the vehicular standards, a novel modeling approach for the Snubberless Dual Active Bridge (DAB) commutation, an innovative integrated ac inductor, and a new experimental modeling method for multiwinding transformers. The contributions are supported by analyses, simulations, and practical experiments

Développement de chargeurs intégrés pour véhicules hybrides plug-in

This thesis consists on the design and realization of a plug-in hybrid vehicle integrated tractiondrive supply. The work turns to a solution of a mutualized converter, in the objective to imagine asolution which shared drive and battery chargers modes, the three-level NPC topology has beenretained. The single phase charger is based on an interleaved PWM rectifier, and motor windings areused as smoothing inductors. A double-boost PFC configuration is introduced to ensure the threephasecharger. Passives are sized in each configuration in order to take in account the whole currentconstraints (LF and HF). The PFC behavior is based on the resonant controllers. Then, a 5 kWprototype has been realized to validate the different application modes.In a second part, a single-stage isolated charger based on a Dual-Active-Bridge (DAB) isproposed. The topology is modeled to the fundamental and the PFC control law is studied. A threephaseconfiguration is simulated in order to achieve higher charging powers and to reduce batterycurrent low-frequency ripple.Ces travaux de thèse consistent en la conception et la réalisation d’une chaîne de tractionintégrée pour véhicule hybride plug-in. L’étude s’oriente vers une solution de convertisseur mutualisé,dans l’objectif de partager la traction et les modes chargeurs de batteries, la structure en NPC à 3niveaux est retenue. Le chargeur monophasé se base une topologie de redresseur à MLI monophaséavec trois bras entrelacés, avec l’utilisation des enroulements du moteur pour le filtrage. En chargeurtriphasé nous adaptons la topologie pour réaliser un montage en double boost triphasé. Pour chaqueconfiguration, les passifs sont dimensionnés pour répondre aux contraintes en courant BF et HF. Lecontrôle adopté se base sur les correcteurs résonants. Enfin, un prototype de 5 kW a été réalisé pourvalider les différents modes de l’application.Dans une seconde partie, nous proposons une solution de chargeur isolé sans étage continu auprimaire à double ponts actifs (DAB). La topologie est modélisée au premier harmonique et unecommande assurant l’absorption sinusoïdale est étudiée. Une configuration isolée triphasée permetl’accès aux puissances plus élevées ainsi que la réduction des ondulations de courant BF en sortie