Antriebe und Energiesysteme von morgen 2022

This paper presents a compact, lightweight direct-drive system for the electric vehicle (EV) segment, which combines the motor, inverter, and brake into a single unit. This enables the entire system to be installed into the wheel and more expansive interiors and battery installation spaces, thus moving the world one step closer to a zero-emissions society. The new motor directly transmits the high driving force necessary to run an EV to the wheels, and its lightweight design and 2.5 kW/kg power density minimize the significant weight increase typically associated with in-wheel units. Moreover, implementing an in-wheel unit does not require a substantial change to the existing configuration of the suspension and other components. Driveshafts and other indirect mechanisms have been eliminated, enabling motor power to be applied directly to EV operation. This reduces energy loss by 30% and increases the range on a single charge compared with existing EVs.

The development of the battery electric vehicle is motivated by the reduction of the CO₂ emissions. Therefore, it is important to understand the main CO₂ contributors during the life cycle of the vehicle. The Life Cycle Assessment of the Taycan confirmed that the battery is responsible for about 40% of the CO₂ emissions during the production of the vehicle. This insight leads to the question of the optimal battery size – to meet the customer’s needs and the environmental targets. By analyzing customers preferences and use cases, Porsche reinforced following presumptions as an important indication for rightsizing the battery.:

In the presentation, we describe how CO₂ emissions can be reduced while considering customer needs. Beside using green energy (CO₂-neutral) for production and in use charging the battery size/capacity is an important factor affecting CO₂ and other environmental factors.

Considering the main factors “CO₂”, “traveling time” and “driving dynamics” a limitation of battery capacity in combination with fast charging is possible. In order to achieve our Vision of “Net Zero CO₂ by 2030” of course recycling is a key success factor.

Among the battery electric vehicles (BEV) a trend towards all-wheel drive (AWD) is visible and the AWD market share is going to grow significantly within the next years. For this reason, it is important to find a way how to increase the overall powertrain efficiency. One possible solution is to disconnect the secondary axle every time the driver demand doesn’t require it to be active. We call this solution eConnect. In this work, different eConnect solutions for AWD BEV and their advantages in terms of efficiency are discussed. In the most AWD BEV (with two electrified axles) the primary axle is used to cover most of the common driving situations. The secondary axle (also boost axle) is activated only for a low percentage of the vehicle lifetime in order to achieve better acceleration or to fulfill particular use cases. It is proven that disconnecting the secondary axle reduces the drag torques and significantly increases the powertrain overall efficiency, increasing the vehicle electric range. This is true also for secondary axles with ASM. ZF is working on different eConnect solution in order to fulfill the customer requirements in terms of performance and costs. One of these solutions was already implemented in a vehicle as a prototype with good results.

The future powertrain mix will not only be influenced by technology and engineering. The properties of fuels, the production of electric energy and the footprint of all mobility elements are mandatory to achieve the global climate targets. To address this, IAV connected it’s technology oriented powertrain simulation methods with the energy and fuel production assessment in one method-chain. In application of this method-chain IAV has investigated powertrain systems with fossil, hydrogen and synthetic fuels and compared it with electricity-based mobility. The results of this study will be presented in order to get an overview about the powertrain effects one the one hand and the cost and CO₂-impact of the energy and fuel production. Beside this the complete life cycle assessment of vehicle with powertrains and the energy/fuel provision will be presented for different detail levels. Based on that results IAV will give a big picture and a clear recommendation about the best balanced powertrain systems in regard of consumption, powertrain footprint, energy/fuel footprint, costs and TCO. Beside this the impact of those systems on the future CO₂-fleet-emissions and the ecological potentials will be addressed.

In the following paper, requirements for long-term power demand prediction algorithms are formulated, that are needed for a successful implementation of prediction-based driving functions and for enabling their potential benefits in series production vehicles. To this end, influencing factors that affect the load profile when driving on a given route are identified and examined for the impact of their availability and information quality. Load predictions of varying accuracy – i.e., in presence or absence of certain information or even misinformation – are generated and analyzed for their potential benefits when applying a range estimation algorithm for battery electric vehicles and a predictive control strategy for hybrid electric vehicles using discrete dynamic programing (DDP). It is demonstrated that the prediction quality has a significant impact on the benefit of these strategies. When the prediction accuracy is low, the energy demand using a DDP strategy that promises globally optimal control may even be increased compared to rule-based strategies. It is also shown that different predictive applications have different requirements on their prediction quality. The results thus provide an important contribution to the improvement of load prediction algorithms and to the introduction of long-term predictive functions to production vehicles in future.

As the transition to e-mobility progresses, not only is the number of battery-electric vehicles increasing, but also the individual battery size. In pursuit of ever higher battery capacities and electric vehicle ranges, we experience a rapidly growing demand for certain raw materials. The technology currently used in electric cars is almost without exception the lithium-ion battery which includes various types of battery chemistries and material composites. Required raw materials such as lithium and cobalt have repeatedly been under criticism. To evaluate the new technology, it is important to examine the environmental footprint of the extraction of raw materials as well as to consider ethical and political circumstances. Furthermore, we need to consider which other options exist as new developments in the field of battery cells show alternatives to established materials. A wide range of possibilities opens up, from cobalt-free cells to sodium-based energy storage systems.

As an independent development service provider in the automotive sector, APL deals with current and future technologies on a daily basis and, in addition to ethical arguments, also knows the economic and technical side of how the choice of materials affects the performance of the battery. In this paper, APL gives deeper insights and illuminates the topic from different perspectives.

Increasing the DC-link voltage up to 800 V brings significant advantages in automotive applications. Faster charging times, lower weight and better efficiencies are some aspects associated with these systems. In this work, a holistic system optimization for an 800 V automotive powertrain with Si-IGBTs and SiC-MOSFETs is discussed. The consideration of the specific challenges for optimizing an inverter for fast switching as well as its consequences at system level are discussed. The choice of the optimal PWM frequency as well as the impact of fast switching on bearing currents are also demonstrated. The efficiency gap between the Si and SiC solutions is derived experimentally and is shown to be very significant in cycle relevant areas. It is demonstrated that only a thorough consideration of the system tradeoffs and physical properties can lead to an optimal solution regarding efficiency, costs and reliability at system level.

On the way to Zero Emission Mobility, no feasible solution for tractors is so far available, as battery electric vehicles are not able to fulfill the requirements for range, refueling time, and weight. Therefore, in the frame of the funded project “FCTRAC”, a fuel cell tractor is developed from an existing diesel vehicle to meet these specific requirements of the powertrain. Due to the limited space in the vehicle and the challenges arising from the thermal management of the fuel cell powertrain, innovative solutions have been developed to achieve the full-operability of the vehicle.

Moreover, no hydrogen fueling infrastructure exists in the operational areas of most of tractor use-cases. Hence, another goal of the project is the development of an input-flexible plant for decentralized production of green hydrogen. Product gas from gasification of wood chips, biogas out of biogas plants, as well as digester gas out of sewage treatment plants are considered as input gases. The proposed solution, the so-called “BioH₂Modul”, can be coupled with these sources and deliver hydrogen to the storage system. As combined heat and power plants using wood gasification, sewage treatment plants, biogas plants are widespread in the agricultural sector, hydrogen can be produced, in the operational areas of the tractors.

The first part of the paper will present the wide range of process units, which can be implemented in the process chain design for decentralized production of high-purity hydrogen from the different feed gases. These process units are consequently classified according to their operating conditions, thus forming the basis for the design of the process chains.

In the second part, the fuel cell powertrain will be described as well as the thermal system and simulation results. Through an innovative packaging in the vehicle, the higher cooling requirements of the fuel cell system are fulfilled even in critical conditions.

In order to develop complex systems that meet the customer expectations, the systems engineering methodology has been successfully applied in many industries. With the goal to break down the customer targets into tangible requirements on sub-system and component level, holistic simulation methodologies are heavily encouraged, as thereby the complex interactions of systems and components can be investigated. In this work, the system engineering methodology and holistic simulation concept is showcased for a fuel cell heavy-duty vehicle, and highlights the workflow and the required toolset from concept to functioning prototype.

EFuels are discussed as an alternative to fossil fuels for several applications within the transport sector. In this paper, a sustainability assessment is presented considering an integrated process chain, which is developed and investigated in the project Kopernikus P2X. The assessment consists of a Techno-Economic Assessment (TEA), an environmental Life Cycle Assessment (LCA) and a literature review about the future production potential. Thereby, the LCA and TEA are based on the results presented in the 3rd roadmap of the Kopernikus P2X project. In addition, the focus is on the implications of the electricity input. The results show that there is an environmental benefit in case of global warming, if renewable electricity is used. Additionally, the improvement can be magnified by increasing the efficiency of the power plants through higher capacity factors at the individual sites. Inexpensive renewable electricity and high full load hours are important for economic considerations. Apart from that, it is likely that policy measures will be required to make production and use of eFuels economical compared to fossil equivalents. The review of potential analyses showed that the majority of the production of eFuels for German demand will most likely not be in Germany. In addition, it can be assumed that the quantity of eFuels that can be produced will not be sufficient for all branches of the transport sector. This necessitates prioritizing those modes of transportation where direct electrification is not possible.

Encouraging users to buy and continuously engage in bidirectional charging are crucial for the long-term success of the technology. However, user research in the context of smart charging has mainly focused on investigating overall perceptions and factors motivating consumers to buy the technology. In this article, we aim to take a more specific perspective on user acceptance of the technology by investigating both their preferences with regard to the design of the business model of bidirectional charging as well as the design of app feedback mechanisms for creating long-term user engagement. Our findings from study 1 reveal that financial aspects (i.e., preferred contractor, type of compensation, willingness to initially invest in the technology) constitute an important factor impacting user participation in bidirectional charging. In the long run, however, users’ non-financial motivation must also be addressed. Therefore, study 2 sheds light on how to foster users’ charging behavior by implementing gamified app feedback (i.e., financial, social, and efficient energy use). With this article, we contribute to user research which has been largely neglected in the highly technology-focused field of bidirectional charging.

Against the backdrop of climate change, Germany has committed to being carbon neutral by 2045. Even assuming a roughly 25% drop in energy consumption by then, it will still be necessary to close a gap of about 1300 TWh/year created by the move away from fossil energy sources. Although a full expansion of all renewable energy sources could theoretically lead to a completely self-sufficient and carbon-neutral supply in Germany, this is hardly conceivable in practice. This would require a massive transformation of the landscape as well as a corresponding acceptance among the population (for example, wind turbines in the vicinity of residential areas). The remaining alternatives are “green” energy imports in the form of hydrogen, eMethane, eFuels or the electricity directly.

Beyond merely obtaining the requisite amount of energy, availability in particular presents a second significant challenge. In general, renewable energy production is subject to volatility. The amount of energy that can be supplied depends on the respective environmental conditions (wind, sunlight) and is thus independent of the actual energy demand. In order to compensate for these fluctuations, energy storage systems of a corresponding size are indispensable. Currently, only synthetic, chemical energy carriers (hydrogen, eMethane, eFuels) can be used for large amounts of energy, such as those needed to store thermal energy for the winter.