Der Antrieb von morgen 2021

From 1990 to 2018, the share of greenhouse gas (GHG) emissions caused by passenger vehicles in the EU increased from about 9% to 14%. Thus, urgent action is required to reduce the GHG emissions of passenger vehicles. Battery electric vehicles (BEV) are a promising option to reduce GHG emissions for passenger vehicles. In this paper, we analyze the GHG emissions and the electricity demand for a BEV over the entire life cycle. We consider the production, utilization and disposal in the current energy system and in a renewable energy system. In both cases, wind electricity is considered for the utilization phase. In the renewable energy system, renewable electricity is applied in the entire supply chain. This also includes the production of materials from hydrogen produced in an electrolysis. The hydrogen is for example used as reducing agent in steel production as well as converted with CO₂ to chemicals and fuels. We integrate the renewable production processes in a database together with the LCA database ecoinvent 3.7. Through the transition from the current energy system to the renewable energy system, the GHG emissions over the entire life cycle decrease from 60 to 5 g CO₂-eq/km. The total electricity demand increases from 0.2 to 0.41 kWh/km. The majority of electricity is required in the production phase.

The environmental friendliness of the battery in a purely battery electric vehicle is subject to increasing criticism. In addition to a high proportion of coal electricity in the electricity mix during vehicle operation, the focus is on the production of the materials inside the battery. Particular attention should be paid to greenhouse gas emissions and the availability of raw materials in cell production, as well as ecological and ethical aspects when mining the required battery raw materials.

In this context, the fuel cell electric vehicle looks more advantageous at first glance, since it only has a small battery. In addition to the typical hydrogen production from natural gas and a Type IV tank, platinum is the most important factor in the life cycle assessment in the fuel cell.

The paper is intended to provide an overview of the current study situation and give a comparative assessment of this complex topic.

Schaeffler is inventing a new electromechanical, discretely switchable valve lift system for commercial vehicle applications: the Schaeffler eRocker Arm System. This modular valve train system can be integrated easily in existing engine setups regardless of the camshaft position and number. It can support exhaust aftertreatment by rapid heat-up and efficient thermal management at extended low load operation. To meet future emission legislations, Schaeffler and IAV investigated various thermodynamic strategies via GT Power on a 12.2 l inline six-cylinder heavy duty engine. Innovative valve lift strategies like early intake valve closure in combination with secondary exhaust valve opening are compared to existing conventional strategies like intake air throttling and combustion phasing. The results show significant potential to increase the exhaust temperature with optimized fuel consumption.

The latest legislative tendencies for on-highway heavy duty vehicles forecast further tightening of the NO_x emissions limits in the European Union and also in the US; a NO_x limit of 0.02 g/bhp-hr – the so called ultra low NO_x limit – has been already approved by the California Air Resources Board (CARB) starting MY2027. In addition, the already phased-in regulations regarding CO₂ enforce also a continuous reduction in CO₂ emissions resp. fuel consumption both in the EU and in the US.

In order to meet low NO_x emission limits, a rapid heat-up of the exhaust aftertreatment (EAT) system is inevitable. However, the required thermal management results in increased fuel consumption, i.e. CO₂ emissions as shown in numerous previous works also by the authors. A NO_x-CO₂ trade-off for cumulative cycle emissions can be observed, which can be optimized by using more advance technologies on the engine and/or on the EAT side.

In the present study a systematic investigation is carried out by means of modelbased holistic approach targeting the definition of optimal engine and EAT layout and thermal management calibration for future legislative emission limits.

Using holistic engine and EAT concept development approach, conventional and advanced EAT layouts are tested. The advanced EAT layout consist of a close-coupled dual-stage SCR system which is directly coupled to the engine model. In order to explore the benefits of each layouts, the engine heat-up calibrations are varied and the resulting, cumulative NO_x-CO₂ emissions of the investigated cycle are compared and evaluated. Also, multiple improvement measures for engine are discussed and an outlook of future powertrain concepts is given.

Increasingly stringent CO₂-regulations demand a reorientation of powertrain concepts in the transport sector. As an example, by 2025 in Europe, CO₂ emissions must be reduced by 15 % and by 2030 by 30 % compared to the 2019 baseline. In the long-term, the focus is also on completely CO₂-neutral powertrain development as aimed for by global GHG regulations.

This publication focuses on the development of CO₂ neutral powertrains with internal combustion engines considering several aspects like fuels (especially hydrogen), powertrain concepts, development methods, and upcoming legislations. Based on the requirements for the development (e.g. CO₂-neutrality, TCO, pollutant emissions), it is described how the development targets can be derived with a holistic approach. This can then be tailored to the specific fleet composition of an individual OEM.

To convert a conventional diesel fueled heavy duty engine to CO₂-neutral operation, key components like combustion system layout, turbocharger, injection and ignition system as well as the controls software structure and the exhaust gas after-treatment system must be redesigned. Several simulations tools and experimental work are combined to identify preferred technical solutions based on specific applications. It will be demonstrated how this process enables an efficient development towards the future powertrain of heavy-duty transportation.

In order to meet future CO₂ emission requirements and to contribute to reducing greenhouse gases of the mobility sector, the vehicle powertrain must prove much better efficiencies than today’s standards. In this context, various engine technologies and alternative fuels need to be considered for the internal combustion engines as well as different hybrid concepts and powertrain configurations. This paper focuses on the usage of methanol due to its promising properties in combination with different hybridized powertrains to determine vehicle efficiency limitations in WLTC and RDE.

For the investigation of the efficiencies of the internal combustion engine, a series of technologically advanced SI engine models are designed and optimized using 0D/1D methods to generate efficiency and BSFC maps for the different engine models that enable the comparison of methanol with gasoline. Thanks to methanol’s much higher knock resistance, the center of combustion can be kept at its optimal value of 8°CA at all times, despite an increase of the compression ratio by about 4 units. Also, the lower combustion temperatures observed during the methanol combustion lead to significant additional benefits.

For a precise quantification of the advantage of methanol, further simulation investigations are conducted by integrating the methanol powered engine into different hybridized powertrains (P1, P2, PS) in a C-segment vehicle. The simulation models (map-based internal combustion engine model, rule-based hybrid strategy, vehicle model, etc.) are embedded into a Co-simulation environment, which allows a robust model-based global optimization by adjusting various component configurations (battery capacity, electric motor power, differential transmission ratio) and operating strategy parameters (load point shifting, gear shifting characteristics). Finally, the different variants are analyzed for several RDE routes and assessed in regard of their robustness of the achieved vehicle efficiencies. It can be shown, that vehicle efficiencies in WLTC of up to 44.7% can be reached using a methanol powered engine and high voltage hybridization which surpasses the achieved efficiencies with a gasoline powered engine and clarifies the efficiency benefits that can be gained through methanol.

Legislative tendencies for on-highway heavy-duty vehicles show a further tightening of NO_x emissions limits for the EU and USA and will be most probably followed by the Non-Road Mobile Machinery (NRMM) sector in the future. The stricter regulations and the upcoming trend for low- and zero-emission construction sides the drivers for alternative propulsion systems in this sector. Multiple propulsion systems including alternative fuels like Hydrogen combustion are currently being developed and some are already on the market.

This study provides a review on the state of the art of alternative propulsion systems including the NRMM specific requirements for off-highway heavy duty applications. In addition to that a model based approach to evaluate different powertrain solutions, depending on machine type and load cycle is presented.

The model based approach is shown by the examples of a medium sized excavator and wheel loader. The internal combustion engine will be included in a powertrain system model in GT-Suite commercial simulation software which contains the respective component models like battery and electrical engines. The control strategy for engine, motors and battery is coupled to the powertrain model with a MATLAB/Simulink system environment. This study focuses on the modelling methodology of the powertrain components and describes their integration into the model.

The simulation study results in a comparison between diesel and multiple hybrid architectures in representative off-highway working cycles. The influence of the engine characteristics, possible advantages of a single-operating point engine concept calibration, recuperation potentials and the general potentials of the hybridization are discussed.

The experiences within this study are showing that a differentiated view by using model based development is essential to evaluate different complex powertrain structures, to define suited operating strategies and to use the potentials which can be offered by the alternative powertrains.

Based on the results an outlook is given on a further CO₂ reduction potentials using hydrogen as an alternative fuel in a combustion engine or for fuel cell technology.

The automotive industry is facing the challenge to realize the turn over to a climate-neutral mobility. The use of fuel cell powertrains is a promising way. Especially the short duration for refuelling in combination with an acceptable range and the separation of energy production and the refuelling process, show the advantages of the powertrain technology against the battery electric vehicle for the customer. Current vehicle concepts use PEM based fuel cells, which provide in combination with low battery capacities the power for the electric motor. The efficiency of the entire powertrain is influenced on the one hand by the design of the fuel cell and the battery size and on the other hand by the dynamic power split.

The current series standard of powertrain topologies are fuel cell vehicles with a big fuel cell system and a small battery size. These powertrains show advantages regarding maximum speed and performance. Due to their size, these powertrains show big challenges in terms of complexity, costs and durability. IAV used their 0D/1D simulation framework to lay out a fuel cell based hybrid powertrain (fuel cell system and battery) with a very long range and high durability for the use in a medium-size passenger car. Beside the long range, also very low costs are possible by the use of a small stack, less components and a low effort for the calibration of the fuel cell system. This powertrain is simulated by different cycles to show the performance in terms of different target values.

Especially in light commercial- and heavy duty vehicle segment a fuel cell propulsion system offers significant advantages in terms of energy density and therewith payload. In order to fit the fuel cell propulsion system to the vehicle requirements a Matlab/Simulink fuel cell propulsion system model is developed and validated on fuel cell system - and vehicle testing results on SEGULA internal fuel cell testbench and vehicle roller dyno.

After this model validation different fuel cell propulsions systems for LCV- and heavy duty applications are simulated. Focus is here on the definition of fuel celland battery power output as well as battery capacity. Beside that the fuel cell system should be run at highest possible efficiencies.

Based on the modeling results a fuel cell dominant approach for light commercial – and heavy duty vehicles is recommended. Fuel cell system continuous power output for LCV is at 70 kW whereas the heavy duty truck tractor has a continuous power output of 210 kW. The LCV can be run with a battery capacity of 1,3 kWh whereas the heavy duty tractor uses 50 kWh battery capacity mainly due to climbing ability requirements.

Various technologies are currently being considered for the reduction of CO₂ emissions in the transport sector. For applications with high range requirements, such as heavy-duty traffic, hydrogen as an energy carrier is a promising option due to its high gravimetric energy density and the possibility of fast refueling. Both the hot conversion in a combustion engine and the use in a polymer electrolyte fuel cell are technically possible.

Hurdles for the market breakthrough of the use in a fuel cell are mainly the infrastructure, the system costs as well as the necessary service life for the application in heavy-duty long-haul trucks. The aim of further development must therefore be to optimize costs while taking the long service life into account.

MAHLE therefore uses the existing know-how of the large-scale production processes for targeted component development. The requirements resulting from the technical component stress serve as a basis. A comprehensive vehicle simulation in GT Suite is used for this purpose. Based on these simulation results, MAHLE components are pre-developed and further optimized for customers.

The paper gives an overview of current technologies and challenges of the fuel cell and its peripheral systems and goes into detail about optimization using the example of the cathode path.

In this paper, we show how to integrate the aspects and activities of electromagnetic compatibility engineering into systems engineering, in order to enable efficient development of complex electromagnetic compatible systems with multidisciplinary requirements and staff. State of the art electromagnetic compatibility engineering and the basic ideas of the systems engineering development approach is shown and we motivate the integration of electromagnetic compatibility engineering into systems engineering. In the main part of this paper, the technical processes of systems engineering are recapitulated and we show how electromagnetic compatibility engineering can be integrated in each process. To this end, we summarise the respective technical process and present the aspects and activities of electromagnetic compatibility engineering to be conducted in the process. Furthermore, we motivate the compilation of an electromagnetic compatibility case from the process outputs as a central argument that electromagnetic compatibility is achieved.

The key component for electrification in the automotive industry is the high-voltage battery system, which supplies the vehicle's high-voltage electrical system and electric drive train and has the largest share in the value chain of an electric vehicle.

In order to be able to certify a high-voltage battery system is ready for series production at the time of its production start, it is necessary to secure the development status at an early stage. Based on various criteria such as mechanical stability, service life and intrinsic safety, a test program corresponding to the maturity level is created for the development object. Depending on the maturity of the high-voltage battery system, different virtual subcomponents and component tests are then carried out. The goal is a to achieve complete validation result that supports further product development in the best possible way, even in difficult aspects such as thermal propagation in the case of a cell thermal runaway. Using the example of thermal propagation, this article shows how FEV covers all phases of development and testing in the context of series development of battery systems for the automotive industry.

A battery system consists of hundreds of battery cells that need to be well understood, monitored and managed to guarantee optimal performance of the overall system. This becomes even more challenging considering that the properties of individual battery cells are subject to certain variability. This applies to new cells due to various manufacturing and environmental factors, and even more so to aged cells. Consequently intensive cell testing needs to be conducted. At APL, new approaches were therefore developed to analyze the electrical, mechanical and thermal behavior, taking into account the deviations of individual cells. In a new type of measurement setup, cells are characterized using laser technology and thermal imaging while being exposed to dynamic load. Simulations are used to determine the influence of parameters such as the state, number and position of deviating single cells on the performance of the overall battery system. The gained insights are combined into an overall system view and validated with battery measurement data during real driving cycles.

The transition of the public transport sector towards a zero emission pathway is a key challenge to address the climate crisis and air quality issues. Bus networks are currently using mainly Diesel vehicles to fulfill the mobility needs of the population. The simple replacement of conventional busses with battery electric models is not feasible in most cases. In this paper, a methodology is presented to choose a technology (depot or opportunity charging, hydrogen/fuel cell) fitting the local circumstances. We find that the grid integration of the charging infrastructure is a main criterion when deciding for a strategy. The challenges and possibilities of grid connection for depot and opportunity charging are presented. Our results consequently show that battery storages and renewable energy power plants can be beneficial and cost effective in the context of energy systems for high power charging stations. In addition, options for synergies with other fleet operators are discussed and the grid integration process of distribution system operators (DSOs) with fleet operators is analyzed based on the legislative framework.

Worldwide charging tests on a wide variety of vehicles and thus several thousand tests and electrically driven kilometers led to the development of a comparable charging index – the “P3 Charging Index”. In addition to the basic principles of vehicle interoperability and the ability to recharge at any charging station, charging performance also plays an important role in the purchasing decision of interested individuals. From the customer's point of view, the recharged range over time is the most important parameter when deciding whether a vehicle is suitable for long distances and can therefore make the combustion engine appear superfluous.

This article is aimed at manufacturers of stationary and mobile charging infrastructures, who play a key role on the road to e-mobility and its acceptance.

Vehicle-to-Grid scenarios show high potential to overcome the challenges of increased energy demand especially in low-voltage grids due to the strong expected ramp-up of electric vehicles (EV) within the upcoming years in Europe. Instead of solving this challenge by relying on conventional grid expansion, which would lead to high investment costs for electrical infrastructure and long lead times, the Vehicle-to-Grid approach provides a more short-term solution in order to avoid critical loads in low-voltage grids, support prosumer movements towards smart grid, optimize local energy consumption, gain electricity savings for EV fleet owners and stabilize the grid by temporarily leveraging electric vehicles’ (EV) battery capacities as flexibilities and feeding energy capacity back into the grid during times of high electricity demand.

Besides the challenges of developing sustainable and scalable business models or investigating the status quo of the regulatory framework, this paper focuses on a readiness check of the technical landscape for integrating EVs into the smart grid. After describing motivation and background of this paper (chapter 1), target charging use cases for bidirectional charging are introduced and Vehicle-to-Grid scenarios for this paper are defined (chapter 2). Then the status quo of charging infrastructure ecosystem for defined Vehicle-to-Grid scenarios incl. main technical requirements are described (chapter 3), before the results of the readiness check for technical implementation of V2G scenarios are shown and summary of key findings and outlook for future studies and projects are given.

From the view of the energy provider integration of e-mobility into smart grid is important, which includes effective dynamic load management and the use of high voltage-batteries in the vehicle to store and feedback energy. The user expects sufficient and reliable charging points to recharge his electric vehicle everywhere and at any time. Professional solutions depend on local conditions and actual request for charging power and energy. For expansion of power grids several studies and recommendations exist already. If controlled charging is implemented expansion of the local distribution systems will be moderate. A communication system connects all partners in the system. It supports all functions for proper grid integration of electric vehicles and charging solutions: charging control, load management, authorization, billing system, bidirectional charging, e-roaming and value added services. Working together with enterprises in various sectors, the automotive industry is in a position to make a significant contribution to our transition to a clean-energy economy, with systems that also propel digitization. In doing so, we can effectively support our climate objectives at a national and international level. These system applications also offer great potential in the new business sectors of digitization.

In this paper, different approaches are presented, based on which a grid-friendly charging of electric vehicles in the local distribution network can be implemented. Two current projects are discussed in more detail. On the one hand, a centralized approach is used here. On the other hand, a decentralized, autonomous solution in the local low-voltage network is being investigated. All the projects presented are tested in the context of field tests, with the aim of converting these approaches into real use if possible after the end of the project. In addition, the current discussion on smart meter gateway technology in Germany has a strong influence on the communication concepts of these solutions.