Electric vehicle

Summary

An electric vehicle (EV) is a vehicle that uses one or more electric motors for propulsion. It can be powered by a collector system, with electricity from extravehicular sources, or it can be powered autonomously by a battery (sometimes charged by solar panels, or by converting fuel to electricity using fuel cells or a generator). EVs include, but are not limited to, road and rail vehicles, surface and underwater vessels, electric aircraft, and electric spacecraft. For road vehicles, together with other emerging automotive technologies such as autonomous driving, connected vehicles, and shared mobility, EVs form a future mobility vision called Connected, Autonomous, Shared, and Electric (CASE) Mobility. EVs first came into existence in the late 19th century, when electricity was among the preferred methods for motor vehicle propulsion, providing a level of comfort and ease of operation that could not be achieved by the gasoline cars of the time. Internal combustion engines were the d

Official source

https://en.wikipedia.org/wiki/Electric_vehicle

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La Chevalière, sauvegarde et extension d’un spécimen de l’habitat intermédiaire français des années 70

Delphine Perrier

Construite dans les années 1970 à Bissy, la résidence La Chevalière propose un nouveau mode d’habiter, entre collectif et individuel. Aujourd’hui, cette réalisation représente, pour beaucoup, les prémices des éco-quartiers. Partant, le projet de sauvegarde et d’extension cherche à actualiser et approfondir ce travail de recherche sur l’habitat intermédiaire. Le projet a débuté par le dessin de logements participatifs groupés profitant chacun d’espaces extérieurs privatifs. Le logement est conçu comme une cellule flexible permettant un avenir en mouvement et donc durable. La nouvelle construction, comme la sauvegarde des logements existants, met l’accent sur des solutions thermiques passives et des matériaux sobres. Les cellules sont regroupées en unités de voisinage autour d’un patio commun, théâtre d’une vie plus collective. Puis, des ruelles, accessibles en petit véhicule électrique, dessinent une séquence urbaine de seuils jusqu’au logement tout en connectant la biodiversité du projet paysager au massif de la Chartreuse. En sauvegardant la ferme préexistante, le projet s’enrichit de programmes collectifs. Cette mixité programmatique est d’autant plus importante que ce nouveau quartier tisse des liens, jusqu’alors révolus, entre La Chevalière, le centre historique de Bissy et ses programmes publics. Il densifie ce tissu périurbain sans créer de rupture d’échelle. Du logis au quartier, les habitants peuvent alors jouir de l’équilibre offert par la tempérance des solutions choisies.

2018

Dealing with Correlations in Discrete Choice Models

Anna Fernández Antolín

The focus of this thesis is to develop methods to address research challenges related to correlation patterns in discrete choice models. In the context of correlations within alternatives, we extend the novel methodology of the multiple indicator solution (MIS) to deal with endogeneity, and show, through its theoretical derivation, that it is applicable when there are interactions between observed and unobserved variables. In the context of correlations between alternatives, we discuss the importance of using models that can capture them, such as cross nested logit models. We show, through real world examples, that ignoring these correlation patterns can have severe impacts on the obtained demand indicators, and that this can lead to wrong decisions by practitioners. We also address the challenge of using revealed preference data, where the attributes of the non-chosen alternatives are unavailable, and propose a solution based on multiple imputations of their empirical distributions. In the thesis, we also contribute to the existing literature by gaining a better understanding of private motorized modes, in terms of modal split and purchases of new cars. Related to modal split, we use a mode choice case study in low density areas of Switzerland. We find that ignoring the car-loving attitude of individuals leads to incorrect value of time estimates and elasticities, which might have severe implications in the pricing schemes of public transportation, for example. Related to the purchase of new cars, we use data from new car acquisitions in France in 2014, and focus on hybrid and electric vehicles. We find elasticities to price that are in line with the literature, and willingness to pay values in line with the market conditions. We also study the impact of different future policy scenarios and find that the sales of new electric vehicles could reach around 1% as a result of a major technological innovation that would render electric vehicles less expensive. In the last part of the thesis, we propose the discrete-continuous maximum likelihood (DCML) framework, which consists in estimating discrete and continuous parameters simultaneously. This innovative idea, opens the door to new research avenues, where decisions that were usually taken by the analyst can now be data driven. As an illustration, we show that correlations between alternatives can be identified at the estimation level, and do not need to be assumed by the analyst. The DCML framework consists in a mixed integer linear program (MILP) in which the log-likelihood estimator is linearized. This linearization might be useful to estimate parameters of other discrete choice models for which the log-likelihood function is not concave (and therefore global optimality is not insured by the optimization algorithms), since for an MILP, a global optimum is guaranteed. We use a simple mode choice case study for the proof-of-concept of the DCML framework, and use it to investigate its strengths and limitations. The preliminary results presented in the thesis seem very promising. To summarize, we develop methods to deal with correlations in discrete choice models that are relevant to real world problems, and show their applicability by using transportation examples. The contributions are therefore both theoretical and applied. The new methods proposed open the door to new research directions in the discrete choice field.

EPFL2018

It is generally agreed that one of the drawbacks of a conventional vehicle is the inability to always reach the best operating point of the engine and the inability to regenerate the kinetic energy. Meaning, even with the help of the gearbox or automatic transmission, there is no way to reach more efficient operating points without increasing the power and then there is nowhere to store the excess of the energy converted. Electric vehicles (EVs) offer an opportunity for intelligent motion by working at the best operating point during driving mode, as well as a smart energy management during charging mode. However, it is well-known that the EV has been criticised due to its range anxiety, its limited compatibility with various charging points, its high cost, as well as its limited capability to ride-through a thermal runaway, etc. Today, the range anxiety seems to be resolved by the fact that a significate development is foreseen in the field of the battery cells market for portable equipment such as cell phones, pads, laptops, etc; the same battery technology can be deployed for EVs. Actually, battery packs in EVs tend to have high energy and power densities which will exert a strong thermal stress upon them. This means that individual battery cells are more prone to decline away and eventually fail early because of an excessive loss of capacity and an increase of the internal resistance caused by accelerated aging. Moreover, for electromechanical reasons, each cell is totally unbalanced in operating mode. Therefore, a suitable battery management system should be installed and the capability of the EV to ride-through thermal runaways must be guaranteed. Furthermore, in order to overcome the difference between AC and DC charging station standards, the EV on-board charger has to be flexible for various levels of charging modes (from AC household basic supply to AC or DC ultrafast charging). In order to meet the EV requirements, an advanced power converter which driven efficiency, power density is required. Therefore, the configurable modular multilevel converter (CMMC) has been introduced. It is part of a family of modular multilevel converters, also known as MMC, M2C or DSCC. Hence, its heritage allows bringing the whole advantages to EV applications. In addition it carries the surname of configurable because the converter plays a double role: in fact, it merge the traction converter and the bidirectional charger as well as the battery balancer converter, which not only increases the modularity and the scalability of the power modules but it reduces the cost, condenses the volume. In detail, the concept is linked to the idea of replacing the branch inductance of the standard MMC by the tapped stator windings of the traction motor itself. This allows operating the stator windings as current filter during charging mode. In addition, the famous EV battery pack is split into the MMC submodule. This will increase the fault ride-through capabilities of the Flex-EV battery against thermal runaways, by increasing the capability of the system to work under fault condition. In addition, states of charge (SoC) balancing are implemented at the level of modulation in order to balance that submodule battery state of charge. This is based on a selecting and sorting algorithm, which connect and disconnect the batteries submodules actively according to the sign of the generated AC current wave form and the SoC of the submodules batteries.

EPFL2016

Dealing with Correlations in Discrete Choice Models

Anna Fernández Antolín

EPFL2018