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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
131

Multi-Objective Optimization of Plug-in HEV Powertrain Using Modified Particle Swarm Optimization

Omkar Mahesh Parkar (10725597) 10 May 2021 (has links)
Increase in the awareness environmental conservation is leading the automotive industry into the adaptation of alternatively fueled vehicles. Electric, Fuel-Cell as well as Hybrid-Electric vehicles focus on this research area with aim to efficiently utilize vehicle powertrain as the first step. Energy and Power Management System control strategies play vital role in improving efficiency of any hybrid propulsion system. However, these control strategies are sensitive to the dynamics of the powertrain components used in the given system. A kinematic mathematical model for Plug-in Hybrid Electric Vehicle (PHEV) has been developed in this study and is further optimized by determining optimal power management strategy for minimal fuel consumption as well as NOx emissions while executing a set drive cycle. A multi-objective optimization using weighted sum formulation is needed in order to observe the trade-off between the optimized objectives. Particle Swarm Optimization (PSO) algorithm has been used in this research, to determine the trade-off curve between fuel and NOx. In performing these optimizations, the control signal consisting of engine speed and reference battery SOC trajectory for a 2-hour cycle is used as the controllable decision parameter input directly from the optimizer. Each element of the control signal was split into 50 distinct points representing the full 2 hours, giving slightly less than 2.5 minutes per point, noting that the values used in the model are interpolated between the points for each time step. With the control signal consisting of 2 distinct signals, speed and SOC trajectory, as 50 element time variant signals, a multidimensional problem was formulated for the optimizer. Novel approaches to balance the optimizer exploration and convergence, as well as seeding techniques are suggested to solve the optimal control problem. The optimization of each involved individual runs at 5 different weight levels with the resulting cost populations being compiled together to visually represent with the help of Pareto front development. The obtained results of simulations and optimization are presented involving performances of individual components of the PHEV powertrain as well as the optimized PMS strategy to follow for given drive cycle. Observations of the trade-off is discussed in the case of Multi-Objective Optimizations.
132

Pseudospectral Collocation Method Based Energy Management Scheme for a Parallel P2 Hybrid Electric Vehicle

Multani, Sahib Singh 06 October 2020 (has links)
No description available.
133

Design of a novel rotary compact power pack for the series hybrid electric vehicle. Design and simulation of a compact power pack consisting of a novel rotary engine and outer rotor induction machine for the series hybrid electric vehicle powertrain.

Amirian, Hossein January 2010 (has links)
Hybrid electric vehicles significantly reduce exhaust emissions and increase fuel economy. Power packs are the most fundamental components in a series powertrain configuration of a hybrid vehicle, which produce the necessary power to run the vehicle. The aim of this project is to design a compact power pack for a series hybrid vehicle, using virtual prototyping. The hybrid electric vehicle characteristics and configurations are analysed, followed by an explanation of the principles of induction machines. A new type of rotary induction machine with an outer rotor construction is designed to be coupled with the novel rotary internal combustion engine with rotating crankcase in order to form the compact power unit for the hybrid vehicle. The starting and generation performance of the designed machine is analysed by an electric machine simulator, called JMAG. ADVISOR software is studied and utilised to simulate the overall vehicle performance, employing different categories of power packs in the powertrain. Results show that the proposed compact power pack has the best performance in terms of fuel economy, emissions and battery charging compared to the existing power unit options. Over the city cycle, fuel economy is increased by up to 47 % with emission reduced by up to 36 % and over the highway cycle, fuel economy is increased by up to 69 % with emission reduced by up to 42 %.
134

Cooperative ADAS and driving, bio-inspired and optimal solutions

Valenti, Giammarco 07 April 2022 (has links)
Mobility is a topic of great interest in research and engineering since critical aspects such as safety, traffic efficiency, and environmental sustainability still represent wide open challenges for researchers and engineers. In this thesis, at first, we address the cooperative driving safety problem both from a centralized and decentralized perspective. Then we address the problem of optimal energy management of hybrid vehicles to improve environmental sustainability, and finally, we develop an intersection management systems for Connected Autonomous Vehicle to maximize the traffic efficiency at an intersection. To address the first two topics, we define a common framework. Both the cooperative safety and the energy management for Hybrid Electric Vehicle requires to model the driver behavior. In the first case, we are interested in evaluating the safety of the driver’s intentions, while in the second case, we are interested in predicting the future velocity profile to optimize energy management in a fixed time horizon. The framework is the Co-Driver, which is, in short, a bio-inspired agent able both to model and to imitate a human driver. It is based on a layered control structure based on the generation of atomic human-like longitudinal maneuvers that compete with each other like affordances. To address driving safety, the Co-Driver behaves like a safe driver, and its behavior is compared to the actual driver to understand if he/she is acting safely and providing warnings if not. In the energy management problem, the Co-Driver aims at imitating the driver to predict the future velocity. The Co-Driver generates a set of possible maneuvers and selects one of them, imitating the action selection process of the driver. At first, we address the problem of safety by developing and investigating a framework for Advanced Driving Assistance Systems (ADAS) built on the Co-Driver. We developed and investigated this framework in an innovative context of new intelligent road infrastructure, where vehicles and roads communicate. The infrastructure that allows the roads to interact with vehicles and the environment is the topic of a research project called SAFESTRIP. This project is about deploying innovative sensors and communication devices on the road that communicate with all vehicles. Including vehicles that are equipped with Vehicle-To-Everything (V2X) technology and vehicles that are not, using an interface (HMI) on smart-phones. Co-Driver-based ADAS systems exploit connections between vehicles and (smart) roads provided by SAFESTRIP to cover several safety-critical use cases: pedestrian protection, wrong-way vehicles on-ramps, work-zones on roads and intersections. The ADAS provide personalized warning messages that account for the adaptive driver behavior to maximize the acceptance of the system. The ability of the framework to predict human drivers’ intention is exploited in a second application to improve environmental sustainability. We employ it to feed with the estimated speed profile a novel online Model Predictive Control (MPC) approach for Hybrid Electric Vehicles, introducing a state-of-the-art electrochemical model of the battery. Such control aims at preserving battery life and fuel consumption through equivalent costs. We validated the approach with actual driving data used to simulate vehicles and the power-train dynamics. At last, we address the traffic efficiency problem in the context of autonomous vehicles crossing an intersection. We propose an intersection management system for Connected Autonomous Vehicles based on a bi-level optimization framework. The motion planning of the vehicle is provided by a simplified optimal control problem, while we formulate the intersection management problem (in terms of order and timing) as a Mixed Integer Non-Linear Programming. The latter approximates a linear problem with a powerful piecewise linearization technique. Therefore, thanks to this technique, we can bound the error and employ commercial solvers to solve the problem (fast enough). Finally, this framework is validated in simulation and compared with the "Fist-Arrived First-Served" approach to show the impact of the proposed algorithm.
135

In-Situ Capacity and Resistance Estimation Algorithm Development for Lithium-Ion Batteries Used in Electrified Vehicles

Varia, Adhyarth C. January 2014 (has links)
No description available.
136

Modeling and Control of a Hybrid-Electric Vehicle for Drivability and Fuel Economy Improvements

Koprubasi, Kerem 16 September 2008 (has links)
No description available.
137

The future of payment systems for public charging of electric vehicles in Sweden : An analysis of possibilities and challenges for a common payment system / Framtidens betalningssystem för publik laddning av elfordon i Sverige : En analys av möjligheter och utmaningar för ett gemensamt betalningssystem

Okur, Melis Irem, Ransed, Sandra January 2021 (has links)
The Swedish car fleet is currently amidst a transition of electrification. This increases the need for an extensive charging infrastructure, and thereby smoothly functioning payment methods for charging. At the time being, there are many charging operators in the market that provide their own payment solutions for charging Battery Electric Vehicles (BEV) and Plug-­in Hybrid Electric Vehicles (PHEV), as the market has developed without any regulations. In consideration of this problem definition, the possibilities and challenges for developing a common payment system was analyzed. With this aim, three key areas were studied: Firstly, the prerequisites for a common payment system in the market was investigated through the historical evolution of such a system in the banking industry. From this, parallels could be drawn to the current market situation of the BEV and PHEV charging industry. Secondly, the problematization was further researched in regard to the customer perspective of the current payment processes. Finally, the prerequisites for a common payment system was analyzed in regard to a company perspective. The three areas were researched through the following three methods: a literary analysis, a questionnaire and a field study at a company. The results show that a need for a unification of payments is present in heterogeneous markets. Therefore, the BEV and PHEV charging market has adequate preconditions for the development of a common payment system considering the innumerable amount of charging operators that currently exist in the market. Furthermore, the results from the questionnaire showed that a majority of BEV and PHEV users are unsatisfied with the current conformation of the payment processes. Lastly, the results show that in regard to the company perspective, there is a satisfactory market climate for entry of a common payment solution considering the business model and technological solution of the analyzed company as well as the customer need. / I takt med att Sveriges bilflotta elektrifieras ökar även behovet av en utbredd laddinfrastruktur och med det ett smidigt sätt att betala för laddningen. I dagsläget tillhandahåller många laddoperatörer egna betalningslösningar för laddning av el­ och laddhybridbilar då marknadens framväxt skett utan reglering. Utifrån denna problemformulering undersöktes möjligheter och utmaningar för ett gemensamt betalningssystem. Under studiens gång undersöktes i detta syfte tre områden: För det första utforskades förutsättningar för ett gemensamt betalningssystem genom att dra historiska paralleller från utvecklingen av ett sådant system inom bankindustrin. För det andra undersöktes problematiseringen utifrån ett kundperspektiv kring dagens betalningslösningar. Slutligen analyserades förutsättningarna för ett gemensamt betalningssystem ur ett företagsperspektiv. Områdena undersöktes genom följande tre metoder; en litteraturstudie, en enkätstudie och en fältstudie på ett företag. Resultaten visar att ett behov av enhetliga betalningar uppstår i samband med heterogena marknader. Därmed har marknaden för laddning av el­ och laddhybridbilar idag goda förutsättningar för ett gemensamt betalningssystem utifrån den variation av laddoperatörer på dagens marknad. Vidare visade enkätresultaten att en majoritet av el­ och laddhybridbilsägare är missnöjda gällande utformningen av dagens betalningsprocesser. Slutligen visade resultaten ur ett företagsperspektiv att det finns goda förutsättningar för introducering av en gemensam betalningslösning utifrån analys av affärsmodell, teknologisk lösning och kundbehov.
138

Optimised space vector modulation for variable speed drives / MLI vectorielle optimisée pour les variateurs de vitesse

Khan, Hamid 06 November 2012 (has links)
Le travail effectué au cours de cette thèse consiste à étudier et développer des techniques innovantes de modulation de largeurs d'impulsions (MLI) qui visent à optimiser les chaînes de traction électriques embarquées dans des véhicules hybrides ou électriques. La MLI joue un rôle stratégique au coeur des variateurs de vitesse, elle influe sur le comportement général de la chaîne de traction et sur sa performance. La MLI présente des degrés de liberté qui peuvent contribuer avantageusement à redimensionner les composants du variateur tels que le circuit de refroidissement, le filtre EMI et le condensateur du bus continu. Les véhicules hybrides constituent une étape naturelle dans la transition énergétique entre les véhicules thermiques et les véhicules électriques. Notre étude contribue à l'optimisation des variateurs de vitesse en général et ceux au coeur des véhicules hybrides ou électriques en particulier. Notre apport consiste à proposer une MLI performante afin de rendre le variateur plus léger et plus compacte tout en garantissant les fonctionnalités traditionnelles. La compétitivité de ces variateurs et par conséquent des véhicules hybrides ou électriques devient alors accessible. Les véhicules hybrides ou électriques utilisent généralement une machine de traction à courant alternatif en raison de nombreux avantages que celle ci présente par rapport à une machine à courant continu. La source d’alimentation au bord d'un véhicule est une batterie, il est donc nécessaire d'utiliser un onduleur pour transformer la tension continue en tension alternative à amplitude et fréquence variables. Le contrôle de cet onduleur est réalisé par des techniques de modulation de largeurs d'impulsions (MLI) ce qui permet ainsi de réguler le couple de la machine. Les techniques MLI produisent une composante basse fréquence, le fondamental qui est le signal désiré et des composantes hautes fréquences appelées harmoniques de commutation qui sont indésirables. Dans les véhicules modernes, il y a de plus en plus de charges mécaniques pilotées par des machines électriques et des systèmes électroniques. Il est impératif d'éliminer le risque d'interférences électromagnétiques entre ces différents systèmes pour éviter le dysfonctionnement ou la défaillance. Il faut donc filtrer ces harmoniques indésirables pour qu'elles ne perturbent pas les calculateurs et autres circuits électroniques de faibles niveaux de tensions. Il existe des techniques de modulation aléatoire (RPWM) qui permettent d'étaler les harmoniques à la fréquence de commutation et ses multiples. Dans cette étude, notre choix s’est porté sur la technique de modulation vectorielle aléatoire (RSVM) qui présente plusieurs avantages par rapport à la MLI intersective. Les machines pilotées par une MLI produisent des tensions de mode commun dites « shaft voltage », qui peuvent provoquer des courants à travers les roulements de la machine, ces derniers pouvant être destructifs. Nous avons pu développer une technique MLI vectorielle basée sur un choix judicieux des vecteurs nuls pour réduire cette tension de mode commun. La chaleur produite par les pertes dans les convertisseurs à commutation dure lors de l'ouverture et de la fermeture des interrupteurs doit être évacuée rapidement, ce qui réduit le stress thermique, évite la défaillance et augmente la durée de vie des interrupteurs. Une technique utilisée pour réduire ces pertes par commutation est la modulation discontinue (DPWM) ; une amélioration est apportée à cette technique dans ce travail. Cette amélioration est présentée sous forme d'une technique discontinue évolutive (EDSVM) qui s'adapte au régime du moteur pour minimiser les pertes. Grâce à cette technique une meilleure distribution du stress thermique sur les différents bras de l'onduleur est rendue possible et permet ainsi d'augmenter la durée de vie de l'onduleur. (...) / The dissertation documents research work carried out on Pulse Width Modulation (PWM) strategies for hard switched Voltage Source Inverters (VSI) for variable speed electric drives. This research is aimed at Hybrid Electric Vehicles (HEV). PWM is at the heart of all variable speed electric drives; they have a huge influence on the overall performance of the system and may also help eventually give us an extra degree of freedom in the possibility to rethink the inverter design including the re-dimensioning of the inverter components.HEVs tend to cost more than conventional internal combustion engine (ICE) vehicles as they have to incorporate two traction systems, which is the major discouraging factor for consumers and in turn for manufacturers. The two traction system increases the maintenance cost of the car as well. In addition the electric drives not only cost extra money but space too, which is already scarce with an ICE under the hood. An all-electric car is not yet a viable idea as the batteries have very low energy density compared with petrol or diesel and take considerable time to charge. One solution could be to use bigger battery packs but these add substantially to the price and weight of the vehicle and are not economically viable. To avoid raising the cost of such vehicles to unreasonably high amounts, autonomy has to be compromised. However hybrid vehicles are an important step forward in the transition toward all-electric cars while research on better batteries evolves. The objective of this research is to make electric drives suitable for HEVs i.e. lighter, more compact and more efficient -- requiring less maintenance and eventually at lower cost so that the advantages, such as low emissions and better fuel efficiency, would out-weigh a little extra cost for these cars. The electrical energy source in a vehicle is a battery, a DC Voltage source, and the traction motor is generally an AC motor owing to the various advantages it offers over a DC motor. Hence the need for a VSI, which is used to transform the DC voltage into AC voltage of desired amplitude and frequency. Pulse width modulation techniques are used to control VSI to ensure that the required/calculated voltage is fed to the machine, to produce the desired torque/speed. PWM techniques are essentially open loop systems where no feedback is used and the instantaneous values differ from the required voltage, however the same average values are obtained. Pulse width modulated techniques produce a low frequency signal (desired average value of the switched voltage) also called the fundamental component, along with unwanted high frequency harmonics linked to the carrier signal frequency or the PWM period. In modern cars we see more and more mechanical loads driven by electricity through digital processors. It is very important to eliminate the risk of electromagnetic interference between these systems to avoid failure or malfunction. Hence these unwanted harmonics have to be filtered so that they do not affect the electronic control unit or other susceptible components placed in the vicinity. Randomised modulation techniques (RPWM) are used to dither these harmonics at the switching frequency and its multiple. In this thesis a random modulator based on space vector modulation is presented which has additional advantages of SVM. Another EMI problem linked to PWM techniques is that they produce common mode voltages in the load. For electric machines, common mode voltage produces shaft voltage which in turn provokes dielectric stress on the motor bearings, its lubricant and hence the possibility of generating bearing currents in the machine that can be fatal for the machine. To reduce the common mode voltage a space vector modulation strategy is developed based on intelligent placement of zero vectors. (...)
139

An Experimental and Theoretical Study of the Mass Transport in Lithium-Ion Battery Electrolytes

Nyman, Andreas January 2011 (has links)
Lithium‐ion batteries are particularly suitable as energy storage solutions in high power applications, such as hybrid electric vehicles. It is generally considered that one of the processes that limit the power density for lithium‐ion batteries is the mass transport in the electrolyte. Yet, it is still difficult to find a set of properties that fully describe the mass transport for the most common electrolytes. In this work, characterization studies of the mass transport were undertaken for two technically important lithium‐ion battery electrolytes: (1) a liquid electrolyte which consist of LiPF6 dissolved in ethyl methyl carbonate (EMC) and ethylene carbonate (EC) and, (2) a gel electrolyte which consists of LiPF6 dissolved in ethylene carbonate, propylene carbonate (PC) and poly(vinylidenefluoride‐hexafluoropropylene) (P(VdFHFP)).The mass transport in the electrolytes was characterized by combining several experiments. The Maxwell‐Stefan equation was used as basis for the characterization. Models of the transport were formulated from the equation and the apparent transport properties were identified. The characterization methods were first analyzed mathematically in order to establish at which conditions the characterization experiments should be performed. The values of the apparent transport properties were then obtained by optimizing the models to the experimental responses. In order to give the characterization results a comprehensible interpretation and to allow benchmarking of electrolytes, the concept of a normalized potential gradient was introduced.The characterization results of the liquid electrolyte were used in a full cell model of a LiNi0.8Co0.15Al0.05O2 | LiPF6 EC:EMC (3:7) | MAG‐10 cell. The model was developed to analyze the mass transport during a hybrid pulse power characterization (HPPC) test. The analysis was made with a method where the polarization was split up into parts each associated with a process within the cell. The optimum composition in terms of mass transport was found to lie between 0.5 and 1.2 mol/dm3 LiPF6 for the liquid electrolyte and between 5 and 7 wt. % LiPF6 for the gel electrolyte. Less amount of polymer in the gel electrolyte gave a faster mass transport. It was also found that the mass transport in the liquid electrolyte contributed to a major part of the polarization during HPPC tests. / Litiumjonbatterier är speciellt lämpliga som ackumulatorer i högeffektsapplikationer som elhybridfordon. Det är idag allmänt accepterat att en av processerna som begränsar effekttätheten för litiumjonbatterier är masstransporten i elektrolyten. Trots detta är det fortfarande svårt att få tag på data som fullständigt beskriver masstransporten i de vanligaste elektrolyterna. I det här arbetet har masstransportkarakteriseringar gjorts för två tekniskt viktiga elektrolyter: (1) en vätskeelektrolyt som består av LiPF6 upplöst i etylenkarbonat (EC) och etylmetylkarbonat (EMC), och (2) en gel elektrolyt som består av LiPF6 upplöst i EC, propylenkarbonat (PC) och poly(vinylidene fluoride‐hexafluoro propylene) (P(VdFHFP)). Masstransporten i elektrolyterna karakteriserades genom att kombinera ett antal karakteriseringsexperiment. Maxwell‐Stefans ekvation användes som utgångspunkt i karakteriseringarna. Modeller av transporten formulerades från ekvationen och de effektiva transportegenskaperna identifierades. En matematisk analys gjordes först av karakteriseringstekniken, så att det kunde fastslås för vilka förhållanden experimenten skulle utföras. Värderna av transportegenskaperna erhölls genom att optimera modellerna till det experimentella beteendet. För att ge karakteriseringsresultaten en begriplig tolkning och för att kunna mäta prestandan av elektrolyter, infördes konceptet normaliserad potentialgradient. Resultatet från karakteriseringen av vätskeelektrolyten användes i en model av en LiNi0.8Co0.15Al0.05O2 | LiPF6 EC:EMC (3:7) | MAG‐10 cell. Modellen utvecklades för att analysera masstransporten i cellen under ett hybridpulstest (HPPC). Analysen gjordes med en metod där polarisationen delades upp i delar som var och en var kopplad till en process i batteriet. Den optimala sammansättningen med avseende på masstransporten låg i regionen 0.5–1.2 mol/dm3 LiPF6 för vätskeelektrolyten och 5‐7 vikt% LiPF6 för gelelektrolyten. Mindre mängd polymer i gelelektrolyten gav en snabbare masstransport. Det konstaterades också att masstransporten i vätskeelektrolyten bidrog med en av de största delarna till polarisationen i HPPC testen. / QC 20110128
140

Μελέτη και κατασκευή κινητήριου συστήματος υβριδικού οχήματος : ενεργειακή διαχείριση μέσω ηλεκτρονικών μετατροπέων ισχύος

Ασημακόπουλος, Παναγιώτης 19 January 2010 (has links)
Η μόλυνση του περιβάλλοντος από τα μέσα μεταφοράς και η συνεχής μείωση των αποθεμάτων των ορυκτών καυσίμων αποτελούν τους δύο κύριους λόγους για τη στροφή των τμημάτων έρευνας της παγκόσμιας αυτοκινητοβιομηχανίας στην επινόηση οικολογικότερων μέσων μετακίνησης. Από αυτή την προσπάθεια προέκυψαν τα ηλεκτρικά υβριδικά οχήματα, τα οποία περιορίζουν την κατανάλωση καυσίμου και τις εκπομπες ρύπων συγκριτικά με συμβατικά οχήματα παραπλήσιων τεχνικών χαρακτηριστικών. Τα υβριδικά οχήματα είναι, ουσιαστικά, ο προάγγελος και το πεδίο δοκιμής και εξέλιξης της αμιγούς ηλεκτροκίνησης. Ο κοινός στόχος της παρούσας διπλωματικής εργασίας και άλλων δύο διπλωματικών εργασιών, οι οποίες εκπονήθηκαν παράλληλα με αυτή, είναι η μετατροπή ενός συμβατικού βενζινοκίνητου αυτοκινήτου σε ηλεκτρικό υβριδικό όχημα. Το αρχικό μέλημα υπήρξε η εύρεση του κατάλληλου οχήματος για τη συγκεκριμένη εφαρμογή. Την προμήθεια του οχήματος ακολούθησε η έρευνα της αγοράς για την εύρεση του κατάλληλου ηλεκτρικού κινητήρα. Ο κινητήρας, ο οποίος επιλέχθηκε, είναι τριφασικός ασύγχρονος. Εν συνεχεία, αγοράστηκαν συσσωρευτές οξέος μολύβδου ως εναλλακτική πηγή ενέργειας του οχήματος. Ακολούθησε εμπεριστατωμένη μελέτη για τη μηχανολογική προσαρμογή του ηλεκτρικού κινητήρα και των συσσωρευτών στο όχημα και πραγματοποιήθηκε αυτή η εργασία. O ηλεκτρικός κινητήρας τοποθετήθηκε επί του διαφορικού, ενώ κατασκευάστηκε ειδική βάση για τους συσσωρευτές. Υπολογίστηκε και κατασκευάστηκε κατάλληλο σύστημα μετάδοσης για τη μεταφορά της κίνησης από τον κινητήρα στον άξονα μετάδοσης της κίνησης του οχήματος, ώστε να ανταποκρίνεται στις ανάγκες κίνησης του. Το γεγονός ότι ο κινητήρας χρειάζεται σύστημα υδρόψυξης για την ασφαλή και αποδοτική λειτουργία του είχε ως αποτέλεσμα την κατασκευή κατάλληλης διάταξης. Το δεδομένο ότι οι συσσωρευτές παράγουν συνεχές ρεύμα, ενώ ο κινητήρας απαιτεί τροφοδοσία με εναλλασσόμενο ρεύμα οδήγησε στην κατασκευή ενός τριφασικού αντιστροφέα ισχύος. Ο αντιστροφέας αποτελεί μια ηλεκτρική διάταξη, η οποία μετατρέπει το συνεχές ρεύμα σε εναλλασσόμενο. Το απαιτούμενο επίπεδο τάσης εξόδου του αντιστροφέα για την τροφοδοσία του κινητήρα προϋποθέτει συγκεκριμένο επίπεδο τάσης στην είσοδο του μετατροπέα, το οποίο είναι υψηλότερο από την τάση εξόδου της συστοιχίας των συσσωρευτών. Επιχειρήθηκε, λοιπόν, η εξομοίωση και η κατασκευή ενός αμφικατευθυντήριου μετατροπέα συνεχούς τάσης σε συνεχή. Η ιδιότητα του είναι η ανύψωση του επιπέδου τάσης των συσσωρευτών κατά τη φάση της τροφοδότησης του κινητήρα αλλά και ο υποβιβασμός της τάσης για τη φόρτιση των συσσωρευτών κατά την επιστροφή ενέργειας από τη λειτουργία του κινητήρα ως γεννήτρια, τη λεγόμενη διαδικασία της αναγεννητικής πέδησης. Ο έλεγχος του ηλεκτρικού κινητήρα πραγματοποιήθηκε μέσω της τεχνικής του άμεσου ελέγχου ροπής (DTC), ενός είδους άμεσου διανυσματικού ελέγχου. / The environmental pollution caused by all means of transport and the continued reduction of stocks of fossil fuels are the two main reasons, which directed the global automotive research in developing “greener” means of transport. From this effort emerged hybrid electric vehicles, which reduce fuel consumption and emissions compared to conventional vehicles with similar technical characteristics. Hybrid vehicles are essentially the precursor and the field for testing and developing pure electric traction. The common objective of this and two other diploma theses, which were prepared in parallel with it, is to convert a conventional gasoline car to a hybrid electric one. The initial concern was to find a suitable vehicle for this application. The supply of the vehicle was followed by the market research to find a suitable motor. The selected motor is a three-phase asynchronous motor. Subsequently, lead acid batteries were purchased as an alternative energy source for the vehicle. This was followed by a thorough study of the mechanical adjustment of the electric motor and battery in the vehicle and the planned work was performed. The electric motor is adapted on the differential and a base was constructed to fit the batteries. A suitable transmission system was built to transmit motion from the electric motor to the transmission axle of the vehicle to meet the needs of the driving conditions. The fact that the motor needs a water cooling system for its safe and efficient operation resulted in the construction of an adequate array. Taking into account that the batteries produce direct current, while the motor requires the supply of alternating current led to the design and construction of a three-phase power inverter at the laboratory. The inverter is an electrical device that converts direct current to alternating current. The demanded level of voltage in the inverter’s output to power the motor requires a specific voltage level at the input of the converter, which is higher than the output voltage of the battery pack. Therefore, the simulation and the construction of a bidirectional DC to DC voltage converter was attempted at the laboratory. The aim is to raise the level of battery voltage during the phase of the electric machine functioning as a motor and to reduce the voltage level to charge the batteries during the phase that the electric machine functions as a generator, a process called regenerative braking. The control of the electric motor was achieved by the technique of direct torque control (DTC), a kind of direct vector control.

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