Predictive control for energy management in all/more electric vehicles with multiple energy storage units

The paper describes the application of Model Predictive Control (MPC) methodologies for application to electric and hybrid-electric vehicle drive-train formats incorporating multiple energy/power sources. Particular emphasis is given to the co-ordinated management of energy flow from the multiple sources to address issues of extended vehicle range and battery life-time for all-electric drive-trains, and emissions reduction and drive-train torsional oscillations, for hybrid-electric counterparts, whilst accommodating operational constraints and, ultimately, generic non-standard driving cycles

Circuit Synthesis of Electrochemical Supercapacitor Models

This paper is concerned with the synthesis of RC electrical circuits from physics-based supercapacitor models describing conservation and diffusion relationships. The proposed synthesis procedure uses model discretisation, linearisation, balanced model order reduction and passive network synthesis to form the circuits. Circuits with different topologies are synthesized from several physical models. This work will give greater understanding to the physical interpretation of electrical circuits and will enable the development of more generalised circuits, since the synthesized impedance functions are generated by considering the physics, not from experimental fitting which may ignore certain dynamics

Observer techniques for estimating the state-of-charge and state-of-health of VRLABs for hybrid electric vehicles

The paper describes the application of observer-based state-estimation techniques for the real-time prediction of state-of-charge (SoC) and state-of-health (SoH) of lead-acid cells. Specifically, an approach based on the well-known Kalman filter, is employed, to estimate SoC, and the subsequent use of the EKF to accommodate model non-linearities to predict battery SoH. The underlying dynamic behaviour of each cell is based on a generic Randles' equivalent circuit comprising of two-capacitors (bulk and surface) and three resistors, (terminal, transfer and self-discharging). The presented techniques are shown to correct for offset, drift and long-term state divergence-an unfortunate feature of employing stand-alone models and more traditional coulomb-counting techniques. Measurements using real-time road data are used to compare the performance of conventional integration-based methods for estimating SoC, with those predicted from the presented state estimation schemes. Results show that the proposed methodologies are superior with SoC being estimated to be within 1% of measured. Moreover, by accounting for the nonlinearities present within the dynamic cell model, the application of an EKF is shown to provide verifiable indications of SoH of the cell pack

System-based Integration of Electric Vehicles in an Electricity System

Die Förderung von alternativen Antriebstechnologien wie z. B. Elektrofahrzeugen, die in das Verkehrs- und Stromsystem integriert werden, muss auf effizienten und wirtschaftlich sinnvollen Umsetzungskonzepten basieren. Eine erfolgreiche Eingliederung von Elektrofahrzeugen in ein Stromsystem wird von geeigneten „Business Cases“ beeinflusst. Die Umsetzung der Mobilitätsbedürfnisse der Fahrzeugnutzer muss als Hauptbedingung jeder Zielfunktion definiert werden. Der Ansatz in diesem Beitrag basiert auf der systematischen Auswertung verschiedener Konzepte zum Auf- (Richtung des elektrischen Stroms vom Netz zum Fahrzeug) und Entladen (Richtung des elektrischen Stroms vom Fahrzeug zum Netz) von Elektrofahrzeugen, die wie folgt unterteilt sind: unkontrollierte, kontrollierte und intelligente Auf- und Entladestrategien. Die betrachteten Konzepte gehören alle zu den kontrollierten Strategien. In allen untersuchten Anwendungen konnten für das Entladen von Batterien (im Fall von LiFePO4-Batterien) keine zufriedenstellenden Ergebnisse erzielt werden. Somit ist eine wirtschaftliche Umsetzung solcher Konzepte nicht möglich. Die Hauptgründe hierfür sind der hohe Kapazitätsverlust der Batterie durch das Entladen und die damit verbundenen Degradationskosten. Daher reichen die voraussichtlichen Einnahmen, die mit den Entladungskonzepten erzielt werden können, nicht aus, um die Kosten für Wechselrichter und die erforderlichen Investitionen für Kommunikations- und Kontrollinfrastruktur zu decken. Was die wirtschaftliche Analyse und den Einfluss der hohen Durchdringungsrate von Elektrofahrzeugen auf Niederspannungsnetze angeht, so ist eine systemrelevante Integration von Elektrofahrzeugen in zwei verschiedene Implementierungsstufen unterteilt.The support of alternative propulsion technologies like electric vehicles being integrated into transport and electricity systems must be based on efficient and economically reasonable implementation concepts. A successful integration of electric vehicles into an electricity system is affected by adequate business cases. The realisation of the mobility needs of vehicle users must be defined as a main constraint for each target function. The approach within this paper is based on systematic analysis of various charging (direction of electric current from grid to vehicle) and discharging (direction of electric current from vehicle to grid) concepts for electric vehicles, which are subdivided into: uncontrolled, controlled and intelligent charging and discharging strategies. The considered concepts are allocated to the controlled one. In all analysed applications, the discharging of batteries (in case of LiFePO4 batteries) cannot achieve sufficient revenues. This makes an economical realisation of such concepts unfeasible. The main reasons are high battery capacity losses due to discharging and the associated battery degradation costs. Therefore, the calculated revenues of discharging concepts are not able to cover inverter costs and the investments needed for the communication and control infrastructure. In terms of economic analysis and the impact of a high penetration level of electric vehicles on low voltage grids, a system-relevant integration of EVs is subdivided into two different implementation stages

An approach to potential evaluation of a contactless energy supply infrastructure for occasional recharging in production related, non-automated material handling

Significant advances have been made in the research and development of electric vehicles (EV’s). Along with the major challenge of energy storage, being also addressed is the efficient design of system energy transfer and consumption. This has had the effect of fundamentally changing perspectives across the mobility and transportation sector. Applied predominantly to road-going vehicles, the industrial context of non-road Electric Vehicles (nrEV’s) and specifically the use of manned electric forklift trucks integrated within the production related materials handling system has, to-date, received far less attention. The overarching aim of this research is to examine the impact and potential for the use of contactless occasional recharging of nrEV’s integrated within a manufacturing line, recognising the need to balance the (sometimes competing) demands of delivering sustainable production while exercising environmental responsibility. Meeting the objectives of this research resulted in the development of a location allocation model for electric charging station determination based on a fundamental understanding of the nature and quality of process inherent key performance indicators (KPI’s) as well as comprehensive process and energy monitoring while considering both Lean and Green Management perspectives. The integration of the generated knowledge and information into a generally valid simulation tool for occasional charging system implementation allows to more thoroughly investigate the impact from occasional charging to overall efficiency and sustainability to be realised. An investigation into relevant literature identified the need for specifically generated energy consumption data and confirmed the need for an energy optimisation model specific to the area of production related materials handling. Empirical data collected from repeated standardised materials handling operations within a selected production related materials handling environment resulted in the development of the Standard Energy Consumption Activity tool (SECA). Further work within this pilot study confirmed the tool as capable of generating reliable and valid data and confirmed the SECA tool as a generally applicable benchmark for energy consumption determination in material handling based on fractional process functions. Integrating this approach into a comprehensive process analysis and charging infrastructure optimisation resulted in the development of an Excel-based simulation model. The (Occasional Charging Station Location Model) OCSLM is based upon Maximal Covering Location Modelling and an endogenous covering distance definition in order to simulate process related potentials and optimal charging system implementation allocations, the target being to increase vehicles usable battery energy. A comprehensive case study based upon six individual and one combined data set confirmed the general and wider applicability of the OCSLM model while the application of the model provides a set of novel results. The application demonstrated a theoretical increase in usable battery energy of between 40% and 60% and within the same case study the impact of technology implementation identified that a reduction in battery and system cost of between 5% and 45% can be realised. However, the use of contactless power transfer resulted in an increase in CO2 emissions of up to 6.89% revealing a negative impact to overall ecology from the use of this energy transfer system. Depending on the availability of fast connecting, contact based energy transmission systems, the approach and results of OCSLM have shown to be directly applicable to contact based systems with resulting CO2 emissions decreasing by 0.94% at an energy transfer efficiency of 96%. Further novelty, of benefit to both academic and industry practice, was realised through the framework and information of the research with the provision of SECA as a process function-based and generally applicable energy consumption standard, OCSLM as a Maximal Covering Location Modell with a focus on occasional charging based on an endogenous covering distance and integrating detailed energy and process monitoring into electric charging station allocation, and the methodology for the application of this approach for fast connecting contactless and contact charging models and cases

Battery, Hybrid and Fuel-Cell Propulsion Systems

The main purpose of the Research is theoretical and experimental evaluation of electric propulsion systems: pure electric ones, fed exclusively by electrochemical energy storage, hybrid electric, in which the power for propulsion comes from different sources, and fuel cell-based vehicles. These studies were carried on through an extended modelling and experimental activity, related to: • Modelling and experimental activities on electrochemical storage systems and super-capacitors, to evaluate their performance and to better individuate the optimal sizing for usage on-board electric and hybrid vehicles. • Design and realisation of a Fuel-Cell based vehicle, starting from the design of the propulsion system, for which dedicated models in Matlab-Simulink® environment were specifically realised, coming to an extended laboratory test activity for all the components, specially for the Fuel-Cell System. • Design of a complete line of electric and hybrid buses, based on the modelling of the propulsion system in collaboration with the manufacturer, through the usage of new object-oriented modelling techniques realised in Dymola-Modelica® environment. After evaluating different energy management strategies, an exhaustive comparison with conventional and electric pure versions has been carried on. The PhD Thesis, after an introduction about innovative propulsion systems, describes in detail all the activities presented, trying to summarise general techniques of design and management for hybrid vehicles