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The winding configuration of an electric machine has a decisive influence on the properties of a traction drive. When designing the electric drive, the optimum compromise must be found between maximum torque, maximum power and high efficiency over a wide operating range. A decisive factor in this design conflict is the choice of the winding configuration. The concept of winding switching offers a way of solving the design conflict and improving the characteristics of the drive through the additional degree of freedom of the variable winding configuration. Switching the number of parallel winding branches in a serial and parallel configuration is a promising approach to overcome the challenge of a high spread between maximum power and high efficiency in customer related driving scenarios of an electric vehicle. The aim of this study is to identify factors influencing the efficiency improvement potential of the winding switching topology under consideration compared to a reference drive
Oestreicher, RaphaelKoenen, ChristianKulzer, André Casal
As a fundamental element of measures to reduce the carbon footprint of commercial applications, carbon-neutral fuels are increasingly coming into focus for heavy installations. In addition to diesel substitute fuels, alternative energy carriers like NG, H2, MeOH and NH3 are gaining increasing attention. The energy conversion of these fuels is typically taking place on the principle of premixed combustion, which places different demands on fuel injection and mixture formation, as compared to optimized diesel-like combustion. Accordingly, the demand to layout multi-fuel capable engine designs centers to a high share on the above-mentioned design that can burn these different fuels with high efficiency and support a high degree of commonality with the in-series engine to carry over reliable operation and to maintain attractive cost figures. FEV has developed the Charge Motion Design (CMD) process, which can be applied to design the intake ports and combustion chambers for multi-fuel
Koerfer, ThomasDhongde, AvnishBoberic, AleksandarZimmer, PascalPischinger, Stefan
Vehicle manufacturers are to reduce the CO₂ emissions of new trucks dramatically within the next decade. That requires to consider emission-free/neutral vehicles in the fleet mix. Especially for the application of heavy-duty (HD) long haul trucks, fuel cell powered trucks demand a holistic concept for the integration of the entire powertrain, its auxiliaries and the complete vehicle’s energy management. In an internally funded research project, AVL built up a Fuel Cell Technology Demonstrator Truck. This vehicle is not intended to go into series production but to show leading-edge solution to challenges these vehicles are facing today. Due to the length restrictions of semi-trailer trucks in Europe, packaging into the chassis without having a rack behind the cabin is an issue as well as the ambient temperature level, at which the fuel system is to be derated. Solutions are highlighted in the article how to reach the performance of today’s standard diesel trucks. Furthermore, the
Döbereiner, RolfSchörghuber, ChristophSchenk, AlexanderSchubert, ThomasStöckl, Bernhard
Thermal runaway in lithium-ion batteries represents a critical safety challenge, particularly in high-voltage battery systems used in electric vehicles and stationary energy storage. A comprehensive understanding of the multi-scale processes that initiate and propagate thermal runaway is essential for the development of effective safety measures and design strategies. This study provides a structured theoretical overview of the thermal runaway phenomenon across four hierarchical levels: electrode, single cell, module, and high-voltage battery system. At the electrode level, thermal runaway initiation is linked to electrochemical and chemical degradation mechanisms such as solid electrolyte interphase decomposition, separator breakdown, and internal short circuits. These processes lead to highly exothermic reactions that, at the cell scale, can result in rapid temperature increases, gas generation, and overpressure. On the module and system levels, thermal runaway can propagate through
Ceylan, DenizKulzer, André CasalWinterholler, NinaWeinmann, JohannesSchiek, Werner
Hydrogen is a promising alternative to conventional fuels for decarbonizing the commercial vehicle sector due to its carbon-free nature. This study investigates the ignition and flame propagation characteristics of hydrogen in a 2-liter single-cylinder optical research engine representative of the commercial vehicle sector. The main objective was to enable high power density operation while minimizing NOx emissions. For that, ultra-lean combustion was employed to lower in-cylinder temperatures, addressing the challenge of NOx formation. To counteract delayed and unstable combustion under lean conditions, an active pre-chamber ignition system was implemented. It uses a gas-purged pre-chamber with separate hydrogen injection and spark plug ignition. Turbulent hot gas jets from the pre-chamber ignite the fresh mixture in the main combustion chamber, enabling faster and more stable ignition compared to conventional spark plugs. Additionally, the low volumetric energy density of hydrogen
Borken, PhilippBill, DanielLink, LukasDinkelacker, FriedrichHansen, Hauke
As global air traffic is expected to increase significantly in the coming decades, reducing the associated climate impact requires scalable solutions. While alternative propulsion technologies such as electric and hybrid-electric systems might offer long-term potential, their current applicability remains limited due to low energy density, limited range and scalability, and system complexity. Consequently, thermodynamic propulsion systems – such as gas turbines and piston engines – are expected to remain dominant in the medium term. In this context, sustainable hydrocarbon-based aviation fuels represent a practical and necessary solution. Certified sustainable aviation fuel (SAF) pathways are currently approved exclusively for use in gas turbines, with certification standards tailored to turbine-specific requirements. Consequently, fuel properties such as cetane number and evaporation behavior are not included in existing specifications. However, when SAF-kerosene blends are used in
Kleissner, FlorianHofmann, PeterVogd, PhilippVauhkonen, VilleKäkölä, JaanaGreve, Alina
Power-split hybrid powertrains represent one of the most advanced and complex types of powertrain systems. The combination of multiple energy sources and power paths offers great potential but results in complex interactions that require improved strategies for optimal efficiency and emission control. The development and optimization of such operating strategies typically involve algorithms that demand fast computational environments. Traditional high-accuracy numerical simulations of such a complex system are computationally expensive, limiting their applicability for extensive iterative optimizations and real-time applications. This paper introduces a data-based approach designed specifically to address this challenge by efficiently modeling the dynamic behavior of power-split hybrid powertrains using cascaded neural networks. Cascaded neural networks consist of interconnected subnetworks, each specifically trained to represent individual drivetrain components or subsystems. This
Frey, MarkusItzen, DirkYang, QiruiGrill, MichaelKulzer, André Casal
The resource-intensive process of road testing constitutes an essential part of the development of powertrain software. A significant proportion of explorative tests and adjustments for use in service are conducted during the vehicle test phase. However, the observed trends of decreasing development cycles and increasing system complexity generate a field of conflicts. In order to address this issue, this paper proposes road test emulation as a data-driven approach for continuously adapting powertrain software to the evolving overall system. A dedicated data strategy is designed to enhance customer-oriented software development. Therefore, test scenarios equivalent to in-service conditions are determined based on customer data. These test scenarios enable an emulation of road testing and the analysis of the system in a real-world operational context from the early stages of the product development process. System-specific data from the vehicle under development itself is utilised to
Martini, TimKempf, AndréWinke, FlorianAuerbach, MichaelKulzer, André Casal
Ammonia has emerged as a compelling carbon-free alternative fuel for applications in sectors such as power generation and heavy-duty transportation, where thermal energy conversion plays a dominant role. Its potential lies in its high hydrogen content, carbon-free combustion, and the feasibility of large-scale storage and transport. However, ammonia’s combustion behavior poses significant challenges due to its low reactivity, characterized by a low laminar burning velocity, high autoignition temperature, and narrow flammability range. These properties hinder stable and efficient operation in conventional internal combustion engines. A common strategy to mitigate these limitations involves blending ammonia with hydrogen—often generated via on-board catalytic cracking of ammonia—which improves ignition and flame speed. Despite these benefits, the presence of hydrogen increases the risk of knock, particularly in high-compression-ratio engines designed to improve thermal efficiency. This
Hurault, FlorianBrequigny, PierreFoucher, FabriceRousselle, Christine
In automotive applications a power electronic converter is used for energy conversion between battery and electrical machine. For high performance drives a lightweight design is demanded. Additionally, a higher efficiency of the inverter results in lower cooling requirements but is often achieved by increasing component weight. Hence, thermal modeling of the components and their interactions is essential to determine the best compromise between weight, efficiency and cooling requirements. In traction inverters the DC-link capacitors, power modules, high voltage electrical connections and low voltage devices dissipate power. In this paper the focus is on the thermal modeling of the DC-link capacitor, power modules and high voltage electrical connections and their system, as the performance of the inverter is defined by these components. The thermal models are derived based on physical properties and geometries. First, the DC-link capacitor thermal model is presented and considers the
Blaschke, Wolfgang MaximilianMengoni, LeonardPflüger, RobinKulzer, André Casal
The path toward carbon-neutral mobility represents one of the greatest cultural transformations in recent human history. Positioned between industrial heritage, emerging mobility technologies, and the energy supply sector are the users of 1.5 billion motor vehicles worldwide. Conflicting publications on raw material availability, energy efficiency, and the climate neutrality of propulsion systems have led to widespread uncertainty. This Illustrated Energy Primer provides a new foundation for orientation. It begins with a visual explanation of the basic concepts of energy and power, followed by illustrative comparisons of typical energy demands in vehicles and households. The focus then shifts to common types of energy generation systems. Using regional examples—from coal-fired power plants to wind farms, solar installations, and balcony solar panels—the guide provides clear and accessible performance benchmarks for energy production. Next, nine individual experience profiles highlight
Daberkow, Andreas
The reliability and durability of vehicles are crucial for the acceptance of new technologies by customers. Realistic test methods are necessary to validate or ensure the lifespan of vehicles and their components, particularly regarding specific conditions such as freeze start. This article provides an overview of the current state of research on the effects of freeze starts on the degradation of fuel cells. With this knowledge, relevant operating and boundary conditions for potential damage of the fuel cell are identified (e.g. start temperature, duration in subzero operation, dehydration). The field data from the BMW demonstrator fleet of iX5 Hydrogen Next were analyzed to gain insights into realistic freeze start related stress to the fuel cells. The dynamics of heating rates and the influence of the operating strategy are best represented on a Fuel Cell System (FCS). An experimental setup for a stack centered test on a FCS was developed including a climatic chamber and a subzero
Schwarz, MarkusAlbert, AlbertEichel, Rüdiger-A.
Ammonia (NH3) is a promising energy carrier and a potentially alternative fuel to selected sectors due to its carbon-free nature and its relatively high energy density. However, its low reactivity and slow flame propagation pose significant challenges for a direct use in an internal combustion engine, and stable operation at all engine’s conditions. This study investigates three combustion strategies for utilizing NH3 in an adapted four-cylinder 2 L turbocharged, compression-ignition engine, adapted for spark-ignition (SI) operation. Initially, the engine was tested using pure ammonia as fuel, obtaining high efficiencies and acceptable stability at medium/high loads. Nevertheless, intense combustion instabilities could not be avoided below a minimum load level (which increases with engine speed), making engine operation unfeasible in approximately 30 % of its operating map. To address these limitations, two enhancement strategies are explored: Firstly, hydrogen (H2) doping pre-mixed
Karageorgiou, DimitriosMyslivecek, MatejGaillard, PatrickGomez-Soriano, JosepGonzález-Domínguez, DavidLujan, JoseAlcarria Laserna, Gerardo
Ammonia is considered more and more as a promising carbon-free fuel for internal combustion engines to contribute to the decarbonization of several sectors where replacing conventional engines with batteries or fuel cells remains unsuitable. However, ammonia properties can induce some challenges for efficient and stable combustion. This study investigates the use of an active pre-chamber ignition system fueled with hydrogen and compares it to conventional spark ignition, with a focus on lean limit operation and early flame development. Experiments were conducted on a single cylinder optical engine with a compression ratio of 9.5, equipped with a quartz window in the piston for natural flame luminosity imaging using a high-speed camera. The engine was fueled with a mixture of 95% ammonia and 5% hydrogen by volume. Ammonia was injected and mixed with air in the intake port while hydrogen was directly injected into the prechamber. As a function of the intake pressure (1.0, 0.9, 0.8, and
Rousselle, Christine MounaimBrequigny, PierreGelé, RaphaëlMoreau, Bruno
To support the transition toward climate-neutral mobility and power generation, internal combustion engines (ICEs) must operate efficiently on renewable, carbon-neutral fuels. Hydrogen, methanol, and ammonia-hydrogen blends are promising candidates due to their favorable production pathways and combustion properties. However, their knock behavior differs significantly from conventional fuels, requiring dedicated simulation tools. This work presents a modeling framework based on quasi-dimensional (QD) engine simulation, including two separate knock prediction models. The first model predicts the knock boundary of a given operating point and combines an auto-ignition model with a knock criterion. The overall methodology was originally developed for gasoline and is here adapted to hydrogen, methanol, and ammonia-hydrogen blends. For this purpose, the relevant fuel properties were incorporated into the auto-ignition model, and a suitable knock criterion was identified that applies to all
Benzinger, SteffenYang, QiruiGrill, MichaelKulzer, Andre CasalPlum, LukasHermsen, PhilippGünther, MarcoPischinger, StefanHurault, FlorianFoucher, FabriceRousselle, Christine
The energy transition initiatives in Germany’s renown coal mining region Lusatia have driven research into Power-to-X-to-Power technologies, where synthetic fuel is produced from renewably sourced hydrogen and captured CO2, and converted to electricity and heat through oxyfuel combustion. This work investigates the multi-objective optimization of oxyfuel gas engine using a stochastic engine model and detailed chemistry. Exhaust gas recirculation (EGR) rate, initial cylinder temperature and pressure, spark timing, piston bowl radius and depth are selected as design parameters to minimize the exhaust temperature at exhaust valve opening and indicated specific fuel consumption (ISFC) corresponding to oxyfuel operation with different dry and wet EGR rates. The optimization problem is solved for a dry EGR and four wet EGR cases with various CO2/H2O fractions, aiming to achieve comparable performance as in conventional natural gas / air operation, and energy-efficient carbon capture. The
Asgarzade, RufatFranken, TimMauss, Fabian
One of the most important components of an electric vehicle is the drive motor. Induction motors are often used for this purpose. During operation of these motors, power loss occurs, especially at high speeds. This power loss corresponds, among other things, to the sum of winding losses, iron core losses and mechanical losses. The power losses generate heat, which causes the temperature in the rotor and stator to rise. The increase in temperature of the components inside the motor can lead to premature wear and fatigue failure. To prevent overheating, the motors are air- or water-cooled. Water cooling can be achieved, for example, by means of jacket cooling. Here, the heat generated is dissipated directly by forced convection. However, the cooling jacket makes it difficult to determine the temperature inside the motor. Determining these temperatures is necessary to protect the motor from premature fatigue. The temperatures inside the motor during operation are of particular interest
Schamberger, StephanieReuss, Hans-Christian
As a zero-carbon fuel, ammonia has the potential to completely defossilize combustion engines. Due to the inert nitrogen present in the molecule, ammonia is difficult to ignite or burn. Even if the ammonia can be successfully ignited, combustion will be very slow and there is a risk of flame quenching, i.e. the flame going out before the ammonia-air mixture has been almost completely converted. Both the difficult flammability and the slow combustion result in high ammonia slip, which should be avoided at all costs. The engine efficiency is also greatly reduced. Safe ignition and burn-through can be achieved by drastically increasing the ignition energy and/or using a reaction accelerator such as hydrogen. The planned paper will use detailed 1D and 3D CFD calculations to show how high the potential of ammonia combustion in an internal combustion engine is when an active pre-chamber is used as the ignition system. As a result of the flame jets penetrating into the main combustion chamber
Sens, Marcvon Roemer, LorenzRieß, MichaelFandakov, AlexanderCasal Kulzer, Andre
The introduction of renewable energy systems offers the opportunity to achieve energy self-sufficiency or autarky in addition to contributing towards carbon neutrality by reducing the dependency on energy logistics. Amidst growing geo-political conflicts and natural calamities, the scenario of energy shortage or disruption of energy logistics is a major threat, especially for Europe due to the significant reliance on import of primary energy. Achieving autarky, however, requires a distinction between energy consumers that need uninterrupted energy supply and consumers that could potentially be cut-off during energy shortages to avoid prohibitive costs resulting from oversizing the system. Critical infrastructure such as hospitals, communication systems, emergency services and key mobility nodes like fuelling stations and charging points needed to sustain the services provided by them, always need continuous energy supply. The architecture in current tools for optimising the design and
Vijay, ArjunThaler, BernhardKöcheler, ValentinOppl, ThomasTrapp, Christian
This specification establishes process controls for the repeatable production of aerospace parts by EB-DED-Wire. It is intended to be used for metal aerospace parts produced by additive manufacturing (AM), but usage is not limited to such applications.
AMS AM Additive Manufacturing Metals
The wing-in-ground effect (WIG) vehicle represents a significant advancement in aerodynamics and vehicle design, leveraging the ground effect phenomenon to enhance lift and reduce drag when flying close to the surface. This unique capability allows WIG vehicles to achieve higher payloads, longer range, and greater fuel efficiency compared to traditional aircraft, making them an attractive option for modern military and global disaster response applications. Wing-in-Ground Effect Vehicles: From Modern Military and Commercial Development to Global Disaster Response discusses future disaster response, logistics, and military applications for WIG vehicles, including the ongoing development of aerospace and transportation technology. Relavant advancements in materials and propulsion systems holds promise for further enhancing WIG performance and operational range. Additionally, cost-effective and powerful flight computers with various types of mission-enabling sensor suites from the
Doo, Johnny
In this study, a Kirloskar TV1 compression ignition engine is put to test using diesel, palm biodiesel (B100), and palm biodiesel–diesel blend (B40D60). Among the tested fuels, engine performance at 75% loading condition with reference fuel diesel showed the highest brake thermal efficiency, brake specific energy consumption, and exhaust gas temperature at 27.78%, 12.96 MJ/kWh, and 335.88°C, respectively. While B100 and B40D60 were observed to give a lower value for the same parameters due to their inferior physiochemical properties. In terms of combustion pressure, mean gas temperature, rate of heat release, and rate of pressure rise, the values observed with B40D60 at 67.39 bar, 1397.76 K, 68.83 J/CAD, and 4.34 bar/CAD, correspondingly are better than B100 due to the presence of diesel. Yet for the same combustion parameters, the values for both the aforementioned fuels are still lower than the results seen with pure diesel fueling. Owing to higher cetane number in comparison to
Balakrishnan, Navaneetha KrishnanChelladorai, PrabhuMuhammad, Syahidah Akmal