New slip control system considering actuator dynamics

A new control strategy for wheel slip control, considering the complete dynamics of the electro-hydraulic brake (EHB) system, is developed and experimentally validated in Cranfield University's HiL system. The control system is based on closed loop shaping Youla-parameterization method. The plant model is linearized about the nominal operating point, a Youla parameter is defined for all stabilizing feedback controller and control performance is achieved by employing closed loop shaping technique. The stability and performance of the controller are investigated in frequency and time domain, and verified by experiments using real EHB smart actuator fitted into the HiL system with driver in the loop

Design Space Exploration in Cyber-Physical Systems

Cyber physical systems (CPS) integrate a variety of engineering areas such as control, mechanical and computer engineering in a holistic design effort. While interdependencies between the different disciplines are key attributes of CPS design science, little is known about the impact of design decisions of the cyber part on the overall system qualities. To investigate these interdependencies, this paper proposes a simulation-based Design Space Exploration (DSE) framework that considers detailed cyber system parameters such as cache size, bus width, and voltage levels in addition to physical and control parameters of the CPS. We propose an exploration algorithm that surfs the parameter configurations in the cyber physical sub-systems, in order to approximate the Pareto-optimal design points with regards to the trade-os among the design objectives, such as energy consumption and control stability. We apply the proposed framework to a network control system for an inverted-pendulum application. The presented holistic evaluation of the identified Pareto-points reveals the presence of non-trivial trade-os, which are imposed by the control, physical, and detailed cyber parameters. For instance the identified energy and control optimal design points comprise configurations with a wide range of CPU speeds, sample times and cache configuration following non-trivial zig-zag patterns. The proposed framework could identify and manage those trade-os and, as a result, is an imperative rst step to automate the search for superior CSP configurations

On Steady-State Cornering Equilibria for Wheeled Vehicles with Drift

In this work we derive steady-state cornering conditions for a single-track vehicle model without restricting the operation of the tires to their linear region (i.e. allowing the vehicle to drift). For each steady-state equilibrium we calculate the corresponding tire friction forces at the front and rear tires, as well as the required front steering angle and front and rear wheel longitudinal slip, to maintain constant velocity, turning rate and vehicle sideslip angle. We design a linear controller that stabilizes the vehicle dynamics with respect to the steady-state cornering equilibria using longitudinal slip at the front and the rear wheels as the control inputs. The wheel torques necessary to maintain the given equilibria are calculated and a sliding-mode controller is proposed to stabilize the vehicle using only front and rear wheel torques as control inputs

Prospects for Plug-in Hybrid Electric Vehicles in the United States and Japan: A General Equilibrium Analysis

Abstract and PDF report are also available on the MIT Joint Program on the Science and Policy of Global Change website (http://globalchange.mit.edu/)The plug-in hybrid electric vehicle (PHEV) may offer a potential near term, low carbon alternative to today's gasoline- and diesel-powered vehicles. A representative vehicle technology that runs on electricity in addition to conventional fuels was introduced into the MIT Emissions Prediction and Policy Analysis (EPPA) model as a perfect substitute for internal combustion engine (ICE-only) vehicles in two likely early-adopting markets, the United States and Japan. We investigate the effect of relative vehicle cost and all-electric range on the timing of PHEV market entry in the presence and absence of an advanced cellulosic biofuels technology and a strong (450ppm) economy-wide carbon constraint. Vehicle cost could be a significant barrier to PHEV entry unless fairly aggressive goals for reducing battery costs are met. If a low cost vehicle is available we find that the PHEV has the potential to reduce CO2 emissions, refined oil demand, and under a carbon policy the required CO2 price in both the United States and Japan. The emissions reduction potential of PHEV adoption depends on the carbon intensity of electric power generation and the size of the vehicle fleet. Thus, the technology is much more effective in reducing CO2 emissions if adoption occurs under an economy-wide cap and trade system that also encourages low-carbon electricity generation.BP Conversion Research Project and the MIT Joint Program on the Science and Policy of Global Change through a consortium of industrial sponsors and Federal grants

Convertisseurs à bobine variable pour applications de transport durables

Abstract: Power electronics converters are key components and enable efficient conversion and management of electrical energy in a wide range of applications. For vehicular use, there is an inevitable need to improve their performance and reducing their size. This is particularly important in case of powertrain DC-DC converters as they are required to have improved performance while respecting the specifications, characteristics and stringent space limitations. These objectives define research targets and a particular progress is essential in the field of passive components, semiconductor devices, converter topologies and control. At the current state of technologies, the passive components particularly the power inductors are dominant components which affect the overall volume, cost and performance of power electronic converters. Considering the aforementioned critical aspects, this thesis proposes a variable inductor (VI) concept in order to reduce the weight and size power inductors which are traditionally bulky and have fairly limited operating range. By modulating the permeability of the magnetic material, this concept enhances the current handling capability of power inductors, controls the current ripples, reduces the magnetic and switching losses, as well as the stresses applied to switching devices. Furthermore, it enables the use of smaller cores which leads to the reduction of mass and volume allowing improvements in the converter operation and its overall performance. However, to integrate it into powertrain DC-DC converters, it is fundamental, to question the design of the component itself, the selection of suitable magnetic core materials, and the control of current in the auxiliary winding and saturation management of magnetic cores. This thesis systematically addresses these different research challenges. A particular attention is paid to the experimental study of a VI prototype to demonstrate the concept on a small-scale in order to explore its viability. Subsequently a detailed characterization was developed using finite element analysis to determine the intrinsic functionality of the passive component. Furthermore, this thesis proposed an RMS current based VI design to reduce oversizing of power inductors for electric vehicles application. In this methodology, the selection of a suitable magnetic core material is a crucial step to assure smaller and efficient converters. Hence, this thesis proposes a simplified approach based on weighted property method (WPM) for an appropriate selection of magnetic core in accordance to the needs of the user. Furthermore, to validate the integration of this concept in DC-DC converter topology used in the powertrain of electrified vehicles, an affine parameterization method is used to design the control parameters and a simple management strategy is proposed to enable dynamic control of the VI. The converter control and the proposed strategy are evaluated through simulations of a complete powertrain of a three-wheel recreational vehicle. The small-scale experimental and simulations, and full-scale simulations have demonstrated an interesting capacity of the VI for improving the performance of DC-DC converters for electrified vehicles and manage the saturation of the magnetic core while reducing the size and weight of magnetic components.Les convertisseurs d’électroniques de puissance sont des composants clés de la conversion et gestion efficace de l’énergie électrique dans une large gamme d’applications. Pour des utilisations véhiculaires, il est inévitablement nécessaire d’améliorer leurs performances et de réduire leur taille. Ceci est particulièrement important dans le cas des convertisseurs à courant continu (CC) de la chaine de traction où des performances améliorées en réponse à une large gamme de variations de charge sont recherchées tout en respectant les spécificités, caractéristiques et limitation d’espace nécessaires aux véhicules électrifiés. Ces objectifs définissent une cible de recherche et en particulier des progrès sont essentiels dans le domaine des composants passifs, des dispositifs semi-conducteurs, des topologies des convertisseurs et leurs commandes pour généraliser l’utilisation de véhicules électriques. Les composants passifs, en particulier les inductances de puissance, sont des composants dominants qui affectent le volume global, le coût et les performances de ces convertisseurs d’électroniques de puissance. Compte tenu de ces aspects, cette thèse propose un concept de bobine variable afin de réduire le poids et la taille des inductances de puissance qui sont traditionnellement encombrantes et ont une gamme de fonctionnement assez limitée. En modulant la perméabilité du matériau magnétique, ce concept améliore la capacité de gestion du courant des bobines de puissance, contrôle les ondulations du courant et réduit les pertes magnétiques et par commutation, bien comme les contraintes appliquées aux dispositifs de commutation. En outre, il permet l’utilisation de noyaux plus petits, ce qui entraîne une réduction de masse et de volume, en permettant une amélioration du fonctionnement du convertisseur et de ses performances globales. Cependant, pour l’intégrer aux convertisseurs CC-CC utilisés dans la chaine de traction, il est fondamental de se questionner sur la conception du composant lui-même, la sélection du matériau magnétique, la commande du courant de l’enroulement auxiliaire et la gestion de la saturation du noyau magnétique. Cette thèse aborde de manière systématique ces différents défis de recherche. Une attention particulière est accordée à l’étude expérimentale d’un prototype de bobine variable pour faire la preuve de concept à petite échelle afin d’explorer sa viabilité. Par la suite, une large caractérisation par éléments finis a été développée pour déterminer le fonctionnement intrinsèque de ce composant passif. De plus, cette thèse propose une méthode systématique de design de bobine variable basée sur le courant RMS pour réduire le surdimensionnement traditionnellement associer aux inductances de puissance pour des applications véhiculaires. Dans cette méthodologie, la sélection appropriée du matériau pour le noyau magnétique est une étape cruciale pour garantir des convertisseurs plus petits et efficaces, donc une démarche de sélection simplifiée basée sur la méthode des propriétés pondérées pour le choix de noyau magnétique approprié au besoin de l’application a été mis au point. De plus, pour valider l’intégration de ce concept dans une topologie de convertisseur CC-CC traditionnellement utilisée dans la chaine de traction des véhicules électrifiés, une méthode de synthèse affine a été utilisée pour définir les paramètres des contrôleurs de courant et une stratégie de gestion de la saturation du noyau a été proposée pour permettre le contrôle dynamique de la bobine variable. La commande du convertisseur et la stratégie ont été évaluées par simulation d’une chaine de traction complète d’un véhicule récréatif réel. Les résultats expérimentaux à petite échelle et simulations à pleine échelle ont démontrés des capacités intéressantes de cette bobine variable pour l’amélioration des performances des convertisseurs CC-CC, ayant la capacité de gestion de la saturation du noyau magnétique tout en réduisant la taille et le poids de ces composants passifs, dans le but de son utilisation dans la chaine de traction des véhicules électrifiés

Comparative analysis of battery electric vehicle thermal management systems under long-range drive cycles

Due to increasing regulation on emissions and shifting consumer preferences, the wide adoption of battery electric vehicles (BEV) hinges on research and development of technologies that can extend system range. This can be accomplished either by increasing the battery size or via more efficient operation of the electrical and thermal systems. This study endeavours to accomplish the latter through comparative investigation of BEV integrated thermal management system (ITMS) performance across a range of ambient conditions (-20 °C to 40 °C), cabin setpoints (18 °C to 24 °C), and six different ITMS architectures. A dynamic ITMS modelling framework for a long-range electric vehicle is established with comprehensive sub models for the operation of the drive train, power electronics, battery, vapor compression cycle components, and cabin conditioning in a comprehensive transient thermal system modelling environment. A baseline thermal management system is studied using this modelling framework, as well as four common thermal management systems found in literature. This study is novel for its combination of comprehensive BEV characterization, broad parametric analysis, and the long range BEV that is studied. Additionally, a novel low-temperature waste heat recovery (LT WHR) system is proposed and has shown achieve up to a 15% range increase at low temperatures compared to the baseline system, through the reduction of the necessary cabin ventilation loading. While this system shows performance improvements, the regular WHR system offers the greatest benefit, a 13.5% increase in cold climate range, for long-range BEV drive cycles in terms of system range and transient response without the need for additional thermal system equipment

NeuralFMU: presenting a workflow for integrating hybrid neuralODEs into real-world applications

The term NeuralODE describes the structural combination of an Artificial Neural Network (ANN) and a numerical solver for Ordinary Differential Equations (ODE), the former acts as the right-hand side of the ODE to be solved. This concept was further extended by a black-box model in the form of a Functional Mock-up Unit (FMU) to obtain a subclass of NeuralODEs, named NeuralFMUs. The resulting structure features the advantages of the first-principle and data-driven modeling approaches in one single simulation model: a higher prediction accuracy compared to conventional First-Principle Models (FPMs) and also a lower training effort compared to purely data-driven models. We present an intuitive workflow to set up and use NeuralFMUs, enabling the encapsulation and reuse of existing conventional models exported from common modeling tools. Moreover, we exemplify this concept by deploying a NeuralFMU for a consumption simulation based on a Vehicle Longitudinal Dynamics Model (VLDM), which is a typical use case in the automotive industry. Related challenges that are often neglected in scientific use cases, such as real measurements (e.g., noise), an unknown system state or high-frequency discontinuities, are handled in this contribution. To build a hybrid model with a higher prediction quality than the original FPM, we briefly highlight two open-source libraries: FMI.jl, which allows for the import of FMUs into the Julia programming language, as well as the library FMIFlux.jl, which enables the integration of FMUs into neural network topologies to obtain a NeuralFMU

Integrated modeling and analysis methodologies for architecture-level vehicle design.

In order to satisfy customer expectations, a ground vehicle must be designed to meet a broad range of performance requirements. A satisfactory vehicle design process implements a set of requirements reflecting necessary, but perhaps not sufficient conditions for assuring success in a highly competitive market. An optimal architecture-level vehicle design configuration is one of the most important of these requirements. A basic layout that is efficient and flexible permits significant reductions in the time needed to complete the product development cycle, with commensurate reductions in cost. Unfortunately, architecture-level design is the most abstract phase of the design process. The high-level concepts that characterize these designs do not lend themselves to traditional analyses normally used to characterize, assess, and optimize designs later in the development cycle. This research addresses the need for architecture-level design abstractions that can be used to support ground vehicle development. The work begins with a rigorous description of hierarchical function-based abstractions representing not the physical configuration of the elements of a vehicle, but their function within the design space. The hierarchical nature of the abstractions lends itself to object orientation - convenient for software implementation purposes - as well as description of components, assemblies, feature groupings based on non-structural interactions, and eventually, full vehicles. Unlike the traditional early-design abstractions, the completeness of our function-based hierarchical abstractions, including their interactions, allows their use as a starting point for the derivation of analysis models. The scope of the research in this dissertation includes development of meshing algorithms for abstract structural models, a rigid-body analysis engine, and a fatigue analysis module. It is expected that the results obtained in this study will move systematic design and analysis to the earliest phases of the vehicle development process, leading to more highly optimized architectures, and eventually, better ground vehicles. This work shows that architecture level abstractions in many cases are better suited for life cycle support than geometric CAD models. Finally, substituting modeling, simulation, and optimization for intuition and guesswork will do much to mitigate the risk inherent in large projects by minimizing the possibility of incorporating irrevocably compromised architecture elements into a vehicle design that no amount of detail-level reengineering can undo