Hochschule Ravensburg-Weingarten
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Fakultät Elektrotechnik und Informatik
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- Fakultät Maschinenbau
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Fakultät Soziale Arbeit, Gesundheit und Pflege
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- Fakultät Technologie und Management
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- Anhänger (2)
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- Mikromobilität (2)
- 48V Batterie (1)
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Institute
The aim of this Project is to create a device which holds a Hall sensor to measure the Hitch angle between the Bicycle and its trailer. The device should be able to rotate the sensors along the z-axis (Hitch). Also, when the bicycle is on an inclined plane (tilted along the y-axis), the device should be able to maintain the position of the sensor and still rotate along the z-axis. The device would constitute a main body which splits in two parts. The top part holds the position marker of the sensor, and the bottom parts holds the active side of the sensor. The active side of the sensor is placed on a cylindrical plate which is connected to a bottom plate. These two plates are placed on two Tapered Roller bearings for easy rota-tion. In one concept, a steel wire is wired through the bottom plate of the sensor, round a pulley system and finally attached to a spring, whereby the spring is secured on a fixed stand. The spring is used to hold the sensors in place when the bicycle turns left or right or inclined uphill or downhill. The reason is to keep the active part of the sensor stationary and the position marker of the sensor rotating. In another concept, a steel wire is wired through the bottom plate of the sensor and directly attached to a spring holder system, whereby this is attached to the bar of the ball and socket joint of the trailer. The reason is to keep the active part of the sensor stationary and the position marker of the sensor rotating. In the final concept, a steel wire is wired through the bottom plate of the sensor and at-tached to the ends of two separate springs, whereby this is attached to the bar of the ball and socket joint of the trailer. The reason is to keep the active part of the sensor stationary and the position marker of the sensor rotating.
The growth in battery electric vehicle sales increases the need for Battery Management Systems (BMS). This work shows a deep dive into the BMS and the development of a hardware in the loop test-bench for such electronic control units. The test bench will be used for teaching and the development of new functions for BMS. This work also serves as a basis for teaching in the field of BMS and covers the most common functions of a BMS like state estimation, e.g. State of Charge, current, temperature and voltage measurements and balancing methods. Additionally, this work shows how data for the parameterization of the BMS is determined using battery cycling measurements and electrochemical impedance spectroscopy (EIS). All this information is used to create an accurate battery pack model for hardware in the loop simulation. The battery model runs on a cell emulator, connected to the BMS. With a graphical user interface, different test scenarios can be applied. Students of the course can insert errors and investigate the behaviour of the BMS.
Das Ziel dieser Abschlussarbeit ist die Entwicklung eines voll funktionsfähigen 48V Akkupacks, welches sowohl in einem Fahrzeug sowie als Heimspeicher genutzt werden kann. Vor allem die Integration des Akkupacks in die elektrifizierte Simson Schwalbe steht hierbei im Vordergrund. Um dies zu erreichen, wurde ein kompletter Entwicklungsprozess angestoßen. Dieser beinhaltet die Literaturrecherche zu den Themen Lithium-Ionen-Zellen und Batteriemanagementsystemen. Anschließend wurde mithilfe eines CAD Modells ein erster Prototyp digital dargestellt. Anhand dieses Prototypen wurden alle Komponenten des Akkupacks beschafft um nachfolgend eine komplette 48V Batterie zu fertigen. Über Feedbackschleifen wurden kontinuierlich
Optimierungen in den Prototypen eingearbeitet, um das Akkupack voll funktionsfähig in das Fahrzeug integrieren zu können. Ein bedeutender Teil in der Entwicklung eines Akkupacks geht auf die Auswahl, als auch die Parametrierung eines Batterie Management Systems zurück. Durch dieses kann das gesamte Akkupack so abgesichert werden, dass eine möglichst lange Lebenszeit erreicht werden kann. Für die richtige Parametrierung spielen vor allem Spannungs- und Temperaturkennlinien eine Rolle.Während des Entwicklungsprozess und den durchgeführten Versuchen kristallisierte sich vor allem das thermische Verhalten des Akkupacks als Herausforderung heraus. Diese konnte durch Abstandshalter verbessert, jedoch nicht vollständig beseitigt werden. Das finale Produkt stellt eine voll funktionsfähige 48V Batterie dar, welche dem Fahrzeug entnommen werden kann. Über einen USB Port können Customer Devices wie Smartphones geladen werden. Zusätzlich kann das Akkupack aufgrund der Tauschbarkeit in einen Heimspeicher integriert werden.
Distribution of Cooling Structures in Water Cooled Electrical Machines using Localized Loss Profiles
(2023)
Cooling is a critical factor for improving power density in electrical appliances, especially in integrated drives for mobile applications. However, the issue of distributed losses in electric machines can lead to hotspots and temperature gradients within the electric drive. Traditional cooling jackets use unidirectional flow without or with evenly distributed cooling structures. This often aggravates the issue of hotspots, resulting in thermal derating and thus limiting the operation range. As well, a non-demand oriented distribution of cooling structures leads to unnecessary pressure losses.
This problem is addressed with a newly elaborated method for distributing cooling elements, i.e., pin fins with varying density distribution inside the cooling channel. Results from previous work, numerical simulations, and measurement data from a planar test bench are used. The approach segments the cooling channel by using a loss profile. This profile and analytic heat transfer calculations are used to determine the required density of cooling elements for dissipating the locally induced losses. For a linear channel with uniformly distributed losses, this results in an increasing number of cooling elements within the channel in fluid flow direction. With localized losses, this will result in an increased density distribution in the respective areas. The method is evaluated by applying it to a planar test channel and investigating the temperature distribution on a test bench. First results indicate that the newly developed cooling element distribution provides an advantageous temperature distribution. The temperature gradient along the cooling channel shows a reduction from 23 K to 9 K with the distributed cooling elements.
The method, previously tested in the linear planar channel, then is applied to the construction of a cooling jacket with a specifically designed two-layer cooling channel. This design is analyzed using CFD, a prototype is currently under production. Tests on the prototype will follow in further investigations.
The power density of electric machines is a critical factor in various applications, i.e. like the power train. A major factor to improve the power density is boosting the electric current density, which increases the losses in the limited volume of the electric machine. This results in a need for an optimized thermal design and efficient cooling. The dissipation of heat can be achieved in a multitude of ways, ranging from air cooling to highly integrated cooling solutions. In this paper, this variety is shown and analyzed with a focus on water cooling. Further various structures in electric machines are presented.
A planar testbench is built to systematically analyze water cooling geometries. The focus lies in providing different power loss distributions along cooling channels, accurate temperature readings in a multitude of locations, as well as the pressure drop across the channel. The test bench results are aligned with simulations and simplified analytical evaluation to support the development process.
The main goal in this paper is to determine temperature gradients in the material close to the stator to quantize the potential for future cooling jacket designs. One question ,to answer is: How large the gradient is considering a realistic power loss distribution. Another sensible point are the different thermal expansions of aluminum used in cooling jackets and the steel core of the stator. This can be bypassed by using a steel cooling jacket. In this case, the performance of a steel cooling jacket compared to an aluminum version is investigated and also if light weight construction can compensate the lower thermal conductivity of steel.
After the analysis, an outlook about future changes of the measurement methods are given and first potentials for future cooling jackets are proposed.
Battery electric vehicle (BEV) adoption and complex powertrains
pose new challenges to automotive industries, requiring
comprehensive testing and validation strategies for reliability and
safety. Hardware-in-the-loop (HIL) based real-time simulation is
important, with cooperative simulation (co-simulation) being an
effective way to verify system functionality across domains. Fault
injection testing (FIT) is crucial for standards like ISO 26262.
This study proposes a HIL-based real-time co-simulation
environment that enables fault injection tests in BEVs to allow
evaluation of their effects on the safety of the vehicle. A Typhoon
HIL system is used in combination with the IPG CarMaker
environment. A four-wheel drive BEV model is built, considering
high-fidelity electrical models of the powertrain components
(inverter, electric machine, traction battery) and the battery
management system (BMS). Additionally, it enables validation of
driving dynamics, routes and environmental influences and provides
a precise analysis of the effect of powertrain system faults on driving
behavior. A possible case for a fault injection is to introduce a shootthrough fault in the inverter. Through the co-simulation, it is possible
to analyze the effects on the powertrain and the vehicle dynamics in
different driving situations (e.g. snow). This work demonstrates that
co-simulation is a valuable tool for the development and validation of
BEVs, and presents specific fault cases introduced into the
powertrain and the resulting effects tested under different driving
conditions. In addition, the study discusses the system's limitations
and future possibilities such as controller hardware integration
(Controller-HIL) and autonomous driving system validation.
Bicycle-drawn cargo trailers with an electric drive to enable the transportation of high cargo loads are used as part of the last-mile logistics. Depending on the load, the total mass of a trailer can vary between approx. 50 and 250 kg, potentially more than the mass of the towing bicycle. This can result in major changes in acceleration and braking behavior of the overall system. While existing systems are designed primarily to provide sufficient power, improvements are needed in the powertrain control system in terms of driver safety and comfort. Hence, we propose a novel prototype that allows measurement of the tensile force in the drawbar which can subsequently be used to design a superior control system. In this context, a sinusoidal force input from the cyclist to the trailer according to the cadence of the cyclist is observed. The novelty of this research is to analyze whether torque impulses of the cyclist can be reduced with the help of Model Predictive Control (MPC). In addition, the powertrain of the trailer is intended to support the braking process of the system with regenerative braking. In the context of this research, a first MPC controller design is carried out and analyzed with the help of a Hardware-in-the-Loop (HIL) approach where the microcontroller of the power electronics is included as hardware to ensure the vehicle dynamics control interacts properly with the lower-level field-oriented control. The battery and motor subsystems are simulated in a Typhoon HIL 604, which is supplemented by a vehicle dynamics model of the trailer that is integrated as a Functional Mock-Up Unit (FMU). First results indicate that the MPC longitudinal dynamics controller supports the driver during acceleration, attenuates the sinusoidal oscillations and reduces the force with which the trailer pushes the bicycle during braking.
In today's AI-driven era, computer vision, including autonomous driving, robotics, and healthcare, is prevalent. How-ever, acquiring ample data while managing resources and privacy constraints is challenging. This article proposes a solution: synthetic data generation. We use CAD software to craft intricate 3D models, process them in Blender, and evaluate quality using metrics like Structural Similarity and PSNR (Peak Signal to Noise Ratio). Synthetic data achieves up to 90% similarity with real data and an average PSNR of 21dB. Our method offers a streamlined, dependable ap-proach for enhancing computer vision, especially in object detection, addressing data acquisition challenges.
Fahrdynamiksimulation von einem Fahrrad mit Anhänger zur Lastenbeförderung in der Mikromobilität
(2023)
Diese Arbeit befasst sich mit der Modellierung und Validierung eines Simulationsmodells in MATLAB/SIMULINK. Es wird untersucht, ob Simulationsergebnisse ähnlich wie in der PKW-Simulation auch für die Mikromobilität (hier Fahrrad plus Anhänger) genutzt werden können. Dafür wurde im Voraus ein Pacjeka Reifen Modell mit der Magic For-mula auf Basis eines Fahrradreifens erstellt. Das Simulationsmodell wurde mit Hilfe eines Anhänger-Prototypen und Realfahrtests validiert. Für die Validierung war es wichtig ein Fahrer-Regler in das System zu integrieren und für die Fahrtests auszulegen. Dieser Fah-rer ist für die Längs- und Querregelung verantwortlich und wurde mit Referenzkurven aus den Messdaten versorgt.
Die Auswertung zeigt eine große Übereinstimmung der Fahrdynamik-Messwerte bei dem hier benutzten Einspurmodell. Um möglichst eindeutige Messergebnisse für den Ver-gleich zu erhalten, muss der Einfluss des Fahrers bei den Testfahrten so klein wie möglich gehalten werden. Es ist möglich ein solches Simulationsmodell mit der Realität zu ver-gleichen und dieses für Fahrdynamik-Regelungen zu nutzen.
Die Studie „Kulturen des Lehrens in der hochschulischen Erstausbildung von Hebammen in
Deutschland“ widmet sich der übergeordneten Frage, wie die Lehre in
Hebammenstudiengängen auf der institutionell-strukturellen und der personellen Ebene
gestaltet wird. Diese Frage wird im Rahmen einer qualitativ-rekonstruktiven Studie und über
eine between-method-triangulation bearbeitet. Dabei werden zwei Synopsen von
Strukturmerkmalen von Studiengängen (2019, 2021), eine Dokumentenanalyse der
Modulhandbücher (2019), Expert*innen-Interviews mit Studiengangsverantwortlichen (2019)
und berufsbiografisch-narrative Interviews mit Lehrenden durchgeführt (2019/2020).
Auf einer institutionell-strukturellen Ebene zeigen die Synopsen, die Dokumentenanalyse und
die Expert*innen-Interviews eine Studienlandschaft, welche sich im Hinblick auf verschiedene
Strukturmerkmale in einem Entwicklungsprozess befindet und personelle und zeitliche
Ressourcen erfordert. Anhand der dokumentarischen Interpretation der berufsbiografischnarrativ Interviews mit den Lehrenden in Hebammenstudiengängen lassen sich drei Lehrtypen rekonstruieren, welche sich in Bezug auf ihre habituellen Muster im berufsbiografischen Werdegang und der handlungsleitenden Orientierungen in Bezug auf die hochschulische Gestaltung von Lehre unterscheiden.
Die Studie beschreibt und rekonstruiert aus verschiedenen Perspektiven Kulturen des Lehrens
in der hochschulischen Erstausbildung von Hebammen und setzt einen Referenzpunkt für
weitere Entwicklungen. Die Ergebnisse betonen sowohl auf institutionell-struktureller Ebene
als auch auf der Ebene der Lehrenden die Relevanz personeller und zeitlicher Ressourcen für
die Implementierung einer kompetenzbasierten, wissenschaftsbasierten und
praxisintegrierenden hochschulischen Erstausbildung. Im Rahmen eines
professionstheoretischen Diskurses betonen die Ergebnisse die Bedeutsamkeit des
Strukturkerns hochschulischen Lehrhandelns für die Herausbildung eines professionellen,
wissenschaftsreflexiven Hochschullehrendenhabitus in Hebammenstudiengängen.
