Do you like to always to be a step ahead? The findings from specific benchmark programs help you to be that decisive step ahead in order to generate design and product ideas in interdisciplinary expert workshops. A neutral assessment of your own developments by a partner such as FEV provides you with that important external perspective.
In addition to the specification of technical product characteristics, the optimization of the cost structure is essential to developing competitive advantages. What is referred to as a “should-cost” calculation is carried out on the basis of a detailed analysis of the dismantled components. The should-cost analysis shows what the relevant product should cost with its current design and under the assumptions made. The results of the cost analysis provide insight into competitive costs and form the basis for defining target costs. As part of structured value analysis and cost reduction workshops, interesting cost reduction measures are determined that can be used to improve your own products.
For electric vehicles, the high-voltage battery represents a major cost item. Accordingly, a main focal point for the cost optimization of electric vehicles is the optimization of the battery. The benchmarking of battery systems newly launched on the market is an important part of the strategic development of the battery systems of the future.
In addition to the battery costs, technical benchmarking provides crucial insights regarding various performance aspects. An advance in energy density, and thus in range, represents a significant, unique selling point. Information on cell chemistry, battery management systems, and thermal management is important data that can be used for the further development of your own systems.
What do you need?
In the automotive field, there are significant differences between different battery applications. Generally speaking, there are three battery types (Figure 1).
The battery in a Mild Hybrid Electric Vehicle (MHEV) serves to power a 48 V onboard network and provides power capacities of up to 30 kW. The batteries of a Hybrid Electric Vehicle (HEV) offer power capacities of up to 200 kW and the batteries for Plug-in Hybrid Electric Vehicles (PHEV) provide, beyond that, an increased electric range and the option of external charging. For this battery type, energy and power density also play an important role. In contrast, traction batteries with high energy density are used for purely electric powertrains. Here, different cell types are to be used depending on the applications. In addition to the electric characteristics, these are also differentiated by design and cell chemistry. There are cylindrical, prismatic and “pouch” cells, as well as different cell chemistries, from the currently popular nickel manganese cobalt oxide (NMC) in various allocations, lithium titanate oxide (LTO), or lithium iron phosphate (LFP). Each technology has advantages and disadvantages with regard to power data, construction details, materials used, manufacturing processes utilized, total costs of ownership (TCO), and longevity.
If you now compare the respective gravimetric or volumetric energy density at the system level, larger differences appear due to cell selection, as well as module and system design. For electric vehicles, this consideration is an important distinguishing feature, since the energy density directly results in the range available to the client (Figure 3). For instance, if you compare newer BEVs, such as the Tesla Model 3 Long Range (2018) and the Hyundai Kona Electric 150 kW (2018), to each other, the differences are clear. The Tesla Model 3 Long Range has an energy capacity of 78 kWh with a battery weight amounting to 457 kg. By way of comparison, the Hyundai Kona Electric 150 kW has an energy capacity of 64 kWh with a battery weight of 452 kg. In the benchmarking comparison at the cell, module, and system level, the differences can now be assigned to technical measures. In this context, development teams can be provided with valuable information for future battery technologies.
In addition to the right cell selection and the construction details at the module and system level, thermal management plays an important role. There are different cooling concepts, from air cooling to indirect cooling using cooling sheets or cooling plates and water glycol, cooling via coolants, and direct cooling with dielectric fluids or the cells themselves (immersion cooling).
The high-voltage traction battery represents up to 50 percent of the total cost of ownership for battery electric passenger cars. It is thus fundamentally necessary to build a deeper understanding of the battery’s cost structure. The battery cells represent the main share of battery costs. In the example shown (Figure 3), the battery cells represent 64 percent of the total battery costs.
Modern battery electric passenger cars typically use lithium ion batteries with NMC (nickel manganese cobalt) cathode material. In particular, expensive material components, such as cobalt, drive the cell costs. One approach to optimizing battery cell costs accordingly consists in reducing the cobalt quantity. Figure 5 shows how, from a previously common uniform distribution (NMC-111), materials richer in nickel are developed (NMC-622, NMC-811, NMC-911). Using this type of optimization of the material composition, the cathode material costs can be reduced by over 40 percent. Further efforts in battery cell development aim to increase power density. A higher power density also means a cost reduction for the same battery range.
Further cost drivers for the high-voltage traction battery are the module and battery casing components, thermal management, and the battery management system (BMS). After exceedingly complex constructions in the early battery generations, the benchmarking of the new battery generations now enables us to recognize clear approaches in terms of modularity and module structures. The goal is the achievement of scale effects and the simplification of the assembly processes.
In the end, the indicated approaches to cost reduction lead to further decreases in battery costs, and thus to an increase in the attractiveness of electric vehicles. While we are still seeing average battery pack costs for fully electric passenger cars amounting to approx. 180 EUR/kWh today, this value will decrease by half, to under 100 EUR/kWh by 2030. A battery with a capacity of 70 kWh will then cost less than 7,000 EUR instead of 12,600 EUR (Figure 5).
As a globally positioned development service provider with over 40 locations worldwide and many development centers, FEV offers extensive benchmarking services for their global clients. Dedicated benchmarking locations have been established in four core regions (Europe, USA, China, and India). Thus, local framework conditions and data can be taken into consideration, and global programmes can be run in parallel.
FEV has been conducting detailed benchmarking studies for more than 25 years. FEV uniquely combines in-depth technical expertise and cost engineering knowledge with strategic management consulting methods. The range of service provision includes extensive technical benchmarking, tear-down studies, cost benchmarking, and a benchmark academy; we also have access to extensive benchmark databases.
In addition to typical vehicle and system dismantling studies with professional photographic and video documentation, FEV engineers analyze the construction details, the functions, the materials, and the manufacturing processes. In order to carry out detailed performance and function tests, FEV has an extensive range of test systems: various on-road driving cycles, test tracks, vehicle test benches, and different system test benches – e.g. for combustion engines, turbochargers, transmissions, batteries, electric engines, fuel cells, performance electronics, and NVH (Noise Vibration Harshness) analyses.
In addition to the focus on the automotive industry, benchmarking programs are carried out for the commercial vehicle field, for agricultural machines and construction machines, and for other technical products.
In a typical benchmark program, FEV procures the target vehicle and equips it with the corresponding measurement technology. Initial tests regarding driving performance and energy consumption can be carried out as part of “micro benchmarking” without damaging the vehicle. For further detailed testing, special measurement technology is incorporated into the system to be analyzed. Specific driving cycles and driving tests on real roads, test tracks, or chassis dynamometers provide detailed measurement data. After the dismantling of the vehicle, FEV engineers place the main components to be analyzed on the test bench. These include the combustion engine, the transmission, the high-voltage battery, or the electric engine. Power characteristics are recorded and measurement data is transferred to FEV scatterbands in order to compare them with other measurement results in the FEV database.
After performance tests have been conducted, FEV Cost Engineering experts analyze materials, manufacturing and assembly processes and carry out a detailed should-cost calculation. The cost analysis provides an extensive cost breakdown and shows key cost drivers. Thanks to the achieved cost transparency, cost reduction ideas can be generated and target costs can be determined. FEV provides a unique overall package of benchmarking services with core findings for your developments and your corporate success.
]]>Currently, automotive manufacturers are amending – or replacing – their vehicle portfolios with electrified applications. Furthermore, new companies are being established worldwide that develop and launch electric vehicles in various manifestations. Driven by this need for new technologies, there is a strong need for support in the development of high-voltage batteries, which FEV can provide from the first concept to serial production and, beyond that, up to recovery and recycling.
The mechanisms described are not exclusively limited to the automotive sector. For commercial vehicle, industrial, and marine applications as well, research is increasingly being conducted regarding how vehicles previously powered by combustion engines can be battery operated. Here, the focus is mainly on smaller commercial vehicles, building machines, or smaller boats.
These changes enable both established and new manufacturers to secure further market share. The resulting pressure on development, and mainly battery development, frequently presents a significant challenge to the manufacturers’ planning. In the current projects, electric drives and batteries are frequently being integrated into existing vehicle architectures (also called mixed architectures) which are build for both conventional and electrified drives. This leads to battery installation spaces with significant free-form surfaces and complex or two-tier battery structures. Such configurations significantly increase the effort and expense required for development with regard to cooling system components, high-voltage performance, low-voltage cable harnesses, understeering devices, holders, and fixing elements.
However, market pressure requires that battery development projects be carried out within the planned time frame, with no possibility for subsequent changes. Battery cells are the core of every high-voltage battery. These cells are the basis for the configuration of the modules that then determine the energy and power of the battery within the corresponding electric wiring.
The enormous increase in demand has considerably restricted the availability of the different cell types and products from different manufacturers. Smaller manufacturers in particular are faced with significant challenges with regard to ensuring cell availability for planned applications. The serial production of battery systems may also prove to be a hurdle within a given development activity. For smaller annual unit quantities in particular, an economically viable concept can be difficult to create under certain circumstances. All this can have a long-term impact on the evolution of development projects.
FEV provides support using its experience from many serial development projects, and can assess the individual situation early on and make corresponding proposals in order to create a stable basis for such a development activity. In this context, the FEV engineering portfolio covers all development activities as well as, when necessary, the identification, recommendation, and qualification of a production partner that will serially produce the battery for the client.
“FEV IS A STRONG PARTNER FOR SMALL SERIAL PRODUCTIONS OF BATTERY SYSTEMS AND HANDLES ALL THE NECESSARY PROCESS STEPS IN THIS CONTEXT”
FEV is capable of offering development services in different manifestations. The basis of the FEV battery development portfolio includes all necessary services for development, from the first battery concept up until serial production, and for providing support beyond.
If required, FEV is also a strong partner for small serial productions of battery systems and handles all the necessary process steps in this context for the preparation and subsequent serial production for batch sizes of up to 1,000 units per year.
Battery-powered electric vehicles will achieve high acceptance in the market when they are at least equal to conventionally powered vehicles in all points relevant to clients
“IN ORDER TO OPTIMIZE THE QUICK CHARGING CAPACITY, THE CELL DESIGN CAN BE ADJUSTED AND THE THERMAL MANAGEMENT CAN BE FURTHER OPTIMIZED”
“THE BASIS OF THE FEV BATTERY DEVELOPMENT PORTFOLIO INCLUDES ALL NECESSARY SERVICES FOR DEVELOPMENT, FROM THE FIRST BATTERY CONCEPT UP UNTIL SERIAL PRODUCTION, AND FOR PROVIDING SUPPORT BEYOND”
Increasing the nickel content within the cell enables a longer range with short charging times. On the other hand, this increase also creates a thermally unstable system, which increases the security challenges. Furthermore, calendar and cyclical aging are increased, which reduces the longevity. However, the substitution of cobalt with nickel has a positive impact on costs. Due to the changed cell design, however, there is an increased risk of lithium plating and overtemperature during rapid charging, which can lead to loss of capacity and thermal runaway. Optimized rapid charging leads to a higher thermal load due to higher currents, which creates bigger challenges for safety. Furthermore, the higher currents lead to reinforced lithium plating, which restricts longevity.
To increase driving performance, the overall system is subject a higher current load. This increases the risk of an overload of the individual components, which can lead to a thermal event or the loss of insulation protection. Furthermore, the higher currents have an influence on cyclical aging as well as on calendar aging due to the higher average temperatures; this, in turn, leads to reduced longevity of the Lithium-Ion batteries. In addition, the lines and the (plug) connectors must be designed to be more robust, which leads to additional costs due to changes in material needs.
If security is increased, there will be additional costs, since further functional measures using hardware (sensors, actuators) and software (algorithms, functions) will become necessary. Larger security reserves in the battery management system can also limit maximum performance, performance reproducibility, and range.
FEV provides consulting with a team of internationally recognized specialists at various sites, OEMs, Tier 1 suppliers, and cell manufacturers or takes over entire projects as part of general development. Initial technical concepts are created and coordinated so that they can be specified in the series development process for the start of production. In addition to the resolution of the described target conflicts in development phases, prototype batteries and small serial productions can be reated and validated on our own test benches for cells, modules, and packs.
]]>The performance capability of batteries is influenced by the quality of the control in addition to the selection of suitable battery cells. For the battery management system, which is one of the core systems with regard to battery development, FEV started developing its own BMS control units as early as 2006 and now has its own modular BMS system in the fourth generation, which, depending on the project requirements, can be implemented efficiently, as well as combined in different ways. This includes the battery management unit (BMU), various cell monitoring units (CMU) for 12, 15 or 18 battery cells, as well as the isolation monitoring unit (IMU). In this context, the BMU is the central unit, which controls the CMUs, the decentralized measurement units.
With the development and protection activity in many projects with a variety of requirements and battery architectures, the hardware components have a B-sample degree of maturity and, in addition to use in prototypes, can be purchased as a white box for serial development. During this continuous development, the availability of the installed components is just as much a focal point as the technical maturity, whereby the topic of obsolescence management is also taken into consideration.
The fifth generation of hardware is currently in an advanced development phase. This generation is suitable, for instance, for installation in battery systems from 48 V to 800 V. Batteries with one or several strands, as well as switchable 400 V/ 800 V batteries, can be controlled and monitored with this. Another advantage of the fifth generation is the four CAN communication channels, as well as the support from CAN-FD, the wake-up via CAN and partial networking. In addition to CAN, the BMU has two LIN channels as well as many inputs and outputs in order to meet the various client requirements. Customized development as per client requirements for serial use is also part of the portfolio.
An individual CMU from FEV monitors the temperature and voltage of up to 18 battery cells. Thanks to our proprietary hardware development and the simple, modular design, the CMU can be rapidly adjusted for the development process of various battery configurations with little effort. During development, the topic of cost optimization was also considered. In this context, a decrease in components, such as plugs, as well as a reduction of the test and manufacturing effort is pursued.
For the development phase, with the Campus Controller, FEV has developed a freely programmable control unit that can take over the various functions of the BMS or other control units, including:
In combination with the FEV “VISION” project, a Bluetooth-based visualization solution, the system is a high-performance tool for various development purposes.
In this project, FEV focuses on the topic of man-machine interface for prototype vehicles. On the one hand, “VISION” is made up of the real time-compatible CAMPUS hardware, which takes over CAN gateway functions in this context and, on the other hand, of a tablet with the corresponding app. The CAMPUS hardware takes over the role of the cybersecurity gateway and connects the CAN network of the battery or the vehicle via a Bluetooth interface with the tablet. This ensures that only the relevant messages are read or sent. The data connection is implemented bi-directionally so that, on the one hand, the relevant system information, such as the charge status of the battery, the power requirement and the rotational speed of the engine, can be displayed on the tablet and, on the other hand, so that the commands from various input instruments (e.g. buttons or sliders) can be sent to the vehicle control units. Using the wireless connection, the tablet can also be outside the vehicle for presentation purposes or handed over to interested parties in order to share technical data during test drives.
It is also possible to exchange information with internet servers and thus record measured data – for instance, using the internet connection of the tablet hardware.
The software of a battery management system is crucially important to the performance of the battery throughout the entire life cycle and has a direct influence on central characteristics of the vehicles – for instance, on the range for purely electric driving modes (PHEV, BEV). Furthermore, the BMS often takes over functions, such as charging times forecasts or the calculation of the available power, which can be seen directly by the client, thereby influencing the vehicle experience. A precise calculation of parameters, such as the State of Charge (SoC) as well as the State of Health (SoH), is the basis for an optimal exploitation of the battery system and is simultaneously very challenging, because these are values that cannot be measured directly. Furthermore, the software is an important component of the safety mechanisms that ensure the safety of the battery system during operation.
The FEV BMS software has been continuously developed since 2006 and, thanks to a modular architecture with lean, AUTOSAR-compatible interfaces, can be used with various BMS systems flexibly and with little effort. Thus, this software is already being used for various battery systems, from small 12 V and 48 V systems up to high-voltage batteries with flexible wiring options. FEV relies here on broad experience, since many projects require fulfilling the individual requirements of the respective client. These requirements arise, for instance, from differences in the E/E layout or the architecture of the battery or from the functional integration into the vehicle. Fundamentally, the software is divided into three components: application, safety, and base software.
The FEV BMS application software is developed in a model-based manner and includes features such as power/current release, charge regulation, SoC/SoH calculation, balancing, contactor control, and battery diagnoses. The software is used on both the FEV BMS hardware and the control units of client suppliers. The porting of the application software to other platforms has already been carried out in several (serial) projects and the interface has thus been continuously optimized in order to keep the adjustment effort as low as possible. This also applies to interfaces to the vehicle. All relevant values can be parameterized or calibrated; this is another decisive factor with regard to the flexibility of the software. Particular attention is paid to the topic of verification and validation of the software. Here, test methods and tools of the FEV Embedded System Test Center (FEST) are relied on, along with HIL test system for battery management systems, which can emulate up to 192 individual cells.
The FEV BMS base software represents a development for FEV’s own BMS hardware. The software achieves the connection to the hardware components of the BMU and the CMUs, as well as provides the application software with, for instance, the storage of values in a “non-volatile memory” along with measurement values and I/Os for various services.
In addition to the development of the BMS software, FEV also supports OEMs and suppliers in developing their own BMS application and/or base software.
The functional safety concept can be developed either for a specific vehicle or as a stand-alone product independent of any vehicle (“off-the-shelf components”). If the development is for a known vehicle, the development of the battery system is directly integrated in the FuSa life cycle of the overall vehicle. This is normally the case for FEV developments. In contrast, if the development takes place independently of any vehicle (“safety element out of context”), a portion of the FuSa overall life cycle for the battery is observed. The integration in the overall vehicle life cycle then takes place at a later point by the vehicle manufacturer. The assumptions must be reviewed with regard to validity and any necessary changes must be processed via change management.
“THE FEV BMS APPLICATION SOFTWARE IS DEVELOPED IN A MODEL-BASED MANNER”
Considered aspects
Functional safety deals with risks that may be triggered by potential malfunctions of E/E systems due to systematic software or random hardware errors. In order to develop the battery system in a sufficiently safe manner according to current standards, FEV complies with the development principles of the ISO 26262 standard. Certain hazards, such as those due to chemical hazards or electric shock, are only considered part of the functional safety if the hazard is directly caused by the E/E function. Applied to the battery system, this means that the prevention of electric shock is primarily covered by the high-voltage safety. HV insulation and touch protection therefore does not fall within the scope of functional safety. However, certain E/E functions can also serve high-voltage safety and, accordingly, fall within the scope of functional safety. This is the case for an HV system switch-off during an accident, since here, the measures taken by HV safety, such as insulation, may be damaged and therefore can no longer be considered sufficient.
Concept phase
During what is known as the concept phase, there is an assessment of the risks that could occur due to malfunctions in the implemented system functions. In the process, FEV follows the approach described in the figure. The result of this hazard analysis and risk assessment (HARA) is the safety goals for the system. The scope of the necessary risk reduction is determined by the ASIL, leading to a classification using the letters from A to D. A typical example of a safety goal for a battery system is “The system should prevent battery thermal runaway” (typically rated by FEV with ASIL C or ASIL D). These safety goals are top-level requirements. Based on these safety goals, a functional safety concept is developed which is described in the functional safety requirements. In addition to detection, the safety concept also includes the emergency measures to be initiated. The creation of the functional safety concept is frequently complemented by failure tree analyses.
Product development phase
The system development phase comes after the concept phase. In this phase, the functional requirements are translated into technical requirements. Accordingly, this step is carried out together with the development of the technical system architecture. During this phase, depending on the ASIL classification of the safety goals, failure tree analyses and FMEAs are required by the ISO26262 standard. This phase then leads to the HW and SW development phases, with the safety requirements being incorporated into these phases.
The battery management system from FEV is also suitable for other applications, such as utilization on the test bench.
To this end, FEV has developed a universal BMS (T-BMS) for battery modules; an expansion for the testing of entire batteries is also possible.
The system is based on an FEV BMU and one or several FEV CMU(s), serving to record cell parameters and their monitoring, as well as to calculate other parameters such as State of Charge (SoC). In this context, client-specific functions for the calculation of the necessary parameters can be implemented in the T-BMS. All entered parameters can be transferred to the test bench in order to record, analyze, and utilization for the test procedure. The T-BMS can naturally be used with FEV battery test benches as well as FEV MORPHEE, which enables us to offer a complete solution (see page 30) for the testing of battery modules. Thanks to the easily adjustable CAN interface, however, the T-BMS can also be utilized with a variety of other test benches.
Via a graphical user interface it is possible to calibrate all essential
parameters of the system, such as the number of connected cells. This allows a simple adaptation to different test requirements.
FEV has investigated how ultimately even a zero-impact combustion engine could be achieved, causing less emissions than those contained in the ambient air. In particular the following targets have been set:
Compared to today’s Euro 6d legislation, this means a reduction of NOX emissions by 99.9 percent and PM emissions by 99.2 percent.
FEV has developed extensive patented and patent-pending development methods in the field of simulation, as well as testing and aging of emission-relevant components, which make it possible to demonstrate high robustness and forecast accuracy at an early stage of development.
Emission simulation at FEV is an essential pillar in the frontloading of development. Presented
for the first time in 2016 at the Vienna Engine Symposium, and further refined since then, this modular FEV simulation toolchain based on the GT-Suite software environment is now an essential part of FEV development activities. Engine raw emissions are modeled based on stationary and transient measurement data from engine and roller test benches. The simulation models of the exhaust aftertreatment follow a map-based approach. Still, discretization of the catalyst monoliths allows a good description of the warm-up behavior to take into account individual, temperature-dependent conversion rates. Figure 1 depicts the all relevant variables which are included in the calculation of the conversion.
Knowledge of which vehicle- and powertrain-specific cycles can lead to the highest emissions is essential for reliable compliance with all emission limits under RDE conditions. FEV has realized an abstraction of such real driving conditions. The result is a derivation of a concise number of parameters. This parameterization allows machine learning techniques to be applied to identify the worst case RDE cycles based on an analysis of a few hundreds of simulated cycles. This methodology has meanwhile been successfully applied in many development projects.
In the course of the development of FEV’S RDE emission simulation methodology, it was identified that initially catalysts could hardly be modeled with sufficient precision. The reason for this lies in the mostly limited measurement data available from catalyst manufacturers and OEMs. However, for a precise prediction of the emissions under RDE boundary conditions, knowledge of the conversion rate at highest space velocities and in a wide temperature range is of high importance. FEV there-fore developed its own equipment that can be used to characterize catalysts under exactly these conditions. The system shown in Figure 2 is designed and proven for exhaust gas mass flows up to those produced by turbocharged V12 engines to measure the conversion efficiency at high mass flows and cold temperatures, such as they occur in a full load acceleration shortly after an engine start.
FEV has established a method for rapid aging of catalysts and GPFs, as well. For GPF aging, the burner test bench is modified allowing oil to be burned in order to generate ash. Different methods have been investigated and finally oil injection was chosen. FEV generated a cycle and oil dosing strategy that is able to reproduce similar aging characteristics as they are found during vehicle durability testing.
Five building blocks form the exhaust aftertreatment concept for achieving zero-impact emissions.
The individual building blocks are discussed below.
NOX aw emissions can be optimized by an adaptation of cat heating calibration. For very retarded ignition timings, a high amount of fuel is required to generate an IMEP that matches the FMEP. This results in dethrottling and a lower rate of internal EGR. The cylinder peak temperature increases and remains on a high level over a longer period of time. As a result, the NOX emissions increase. To achieve a drastic reduction in NOX emissions, an optimized cat heating calibration would therefore use only a mild spark timing retardation. As a consequence, HC raw emissions would increase, and additional measures need to be implemented to address this.
Two electrically heated catalysts are integrated upstream of the main catalyst (4 kW per disc, 8 kW in total). The metallic substrate heats up rapidly achieving light-off after a few seconds. However, an engine start followed by cold exhaust gas flowing across the electrically heated catalysts would drop their temperature below the level needed for sufficient conversion efficiency. Therefore, a secondary air pump is used to flow air across the electrically heated catalysts prior to the engine start in order to heat up the main catalyst as well. Figure 4 illustrates the heat up process of the final system configuration. The convective heat transfer can clearly be seen in the lower half of the diagram. As soon as the engine is started the higher exhaust mass flow leads to even better convective heat transfer but at the same time also a reduction in the temperatures.
Emissions can be further optimized by ensuring that the catalyst system maintains a high temperature level. In a hybrid engine, this can be supported by the operation strategy and re-activation of the electrically heated catalysts.
One way to achieve emission adsorption is by dedicated coatings. In order to achieve a high adsorption efficiency, low temperatures are necessary. This matches with the lower incoming exhaust gas temperatures due to advanced ignition timings during cat heating. A metal substrate is considered since this allows high thermal inertia and thus low temperature increase in the first seconds of engine operation and an even distribution of the secondary air mass flow to the inlet face of the electrically heated catalyst. With a temperature limit of 850 °C the adsorption catalyst dictates the position of the exhaust aftertreatment system to be not closed coupled which in turn has benefit regarding thermal aging. Figure 5 shows a comparison of cat heating with and without HC adsorption, in this case downstream of the catalyst.
For exhaust aftertreatment systems targeting at catalyst pre-heating with a burner instead of electrically heated catalysts, the adsorption of the burner emissions via a small carbon canister positioned downstream of the catalyst might be a good solu-tion as well.
The catalyst volume is increase by 30 percent compared to the Euro 6d-TEMP base-line which is already using a bigger catalyst volume compared to former Euro 6b/c levels. This includes the volume of electrically heated catalysts. As a consequence, the space velocity at rated power is reduced to values at which high conversion efficiency can be maintained even in aged conditions.
Best-in-class Euro 6c and Euro 6d-TEMP engines without GPF already achieve PM emissions in WLTC of only 0.12 – 0.28 mg/km. Compared to the zero-impact target of 25 µg/m³ (approx. 0.02 mg/km), there is the need for a further PM emission reduction by 83 – 93 percent. This can well be achieved with a second generation GPF.
The outlined exhaust aftertreatment system is finally assessed in combination with a 2.0 l 4-cyl. turbocharged GDI engine in a plug-in hybrid configuration. Figure 6 shows the final exhaust aftertreatment system.
Extensive DoE investigations have been performed in order to achieve the zero-impact emission level while minimizing the fuel consumption penalty that arises from the electric pre-heating of the catalysts. Figure 7 depicts the correlation between the electrical pre-heating energy and all resulting gaseous emissions. Valid points fulfill the zero-impact target of NOX emissions lower than 40 µg/m³ as well as a balanced SOC of the battery at the end of the cycle. The optimum for meeting the zero-impact target at best possible fuel consumption is found slightly below 0.4 kWh. HC and CO emissions remain well below FEV’s anticipated Euro 7 limits. But, due to the concept, those emissions are not as drastically reduced as the NOX emissions.
The final results for the optimal operation strategy are depicted in Figure 8. The remaining NOX emissions – although hardly visible – mainly result from the first seconds after engine start. The oxygen storage capacity of the catalyst is completely filled at that time and initial rich operation is required to purge the catalyst before full NOX conversion efficiency is achieved. In the remaining part of the WLTC, NOX emission slips remain minimal. The electrically heated catalysts are re-activated for short intervals during the cycle to ensure the temperatures stay on a sufficiently high level at all times. Fuel consumption increases by 4.3 percent compared to the Euro 6d-TEMP baseline.
The zero-impact emission concept presented here is extremely biased towards achieving minimal NOX emissions. For the fulfillment of “just” the Euro 7 emission limit, several conceptual adaptations are possible, e.g. reduction of the number of electrical heated catalysts from two to one. Moreover, the adsorption catalyst could be eliminated, allowing the entire catalyst system to be re-located back to a closed coupled position.
]]>The main concept was to locate the exhaust aftertreatment system (EATS) directly downstream of the exhaust manifold, but upstream of the turbine as shown in Figure 1, so that the best CO2 reduction potential and the best aftertreatment performances can be achieved simultaneously.
The engine hardware and PT-EATS were designed and optimized via simulation to identify the best layout of the catalysts and to quantify the potential benefits for CO2 and NOX emissions reduction. The 48V system, made up of a belt starter generator (BSG) with the associated control components, an electric assisted turbocharger (e-TC) and the 48V battery as well as PT-EATS, were integrated to the existing engine model. The simulations optimized EATS component sizes to achieve successfully the integration within the engine bay. The e-Turbo was dimensioned in GT Power and moreover the EGR strategy was optimized to meet the extremely low engine-out NOx emission targets. Furthermore, the recuperation potential was established by using the simulation model. The original exhaust manifold was rotated 180 °C to enable the integration of the turbocharger and a larger EGR cooler was inserted to allow EGR to be used during full-load operation. Additional design modifications were made to the intercooler bracket, the water lines and air lines to allow the complete packaging within the engine bay of the chosen J-Segment demonstrator vehicle.
Placing the aftertreatment system upstream of the turbine results in an altered enthalpy and thermal inertia profile over the turbocharger compared to a conventional arrangement (Figure 2). The introduction of a 48V electric system to the vehicle enables the incorporation of a pre-turbine aftertreatment system via the integration of an e-TC which compensates the loss of pressure and temperature caused by the increased thermal inertia of the PT-EATS.
In the early phases of operation, the temperature before turbine is significantly lower than without the PT-EATS, owing to the increased thermal mass, but as the exhaust system heats up, a thermal lag and overall temperature offset is seen as a result of the higher thermal mass upstream of the turbine. The heat loss profile over the PT-EATS leads to a calculated cumulative enthalpy loss of ~ 4 percent over a WLTC (Figure 2). In order to maintain the boost pressure levels in such low enthalpy phases, the electric turbocharger generates additional boost pressure, it is also used to recuperate excess energy whenever possible.
The recuperation potential of the system was investigated at two part load operating points, shown in Figure 3. The comparison of the brake specific fuel consumption for 2 recuperation strategies was investigated and shown in Figure 3. Recuperation at the turbocharger via VGT is compared with the extraction of the same power over the BSG via an operating point load shift. The latter strategy shows a more energy-efficient path by up to 3.3 percent, as closing the VGT increases the pump losses, as seen in Figure 3, right. It should be noted however that increasing recuperation increases fuel consumption as additional power is needed to generate the same effective power.
The sizing of the e-TC was considered, as a larger turbine could reduce fuel consumption via optimized pumping losses, but, as typical passenger car driving scenarios are not significantly impacted by pumping loss based fuel consumption penalties, there was minimal benefit to upsizing the e-TC as the electrical boost required during transient operation would be increased so a smaller turbine was chosen. The key criteria in determining the size of the e-machine used is the transient response behavior of the vehicle. An acceleration from a standstill to 100 km/h was simulated with different sizes of e-TC to see which could achieve a comparable acceleration behavior to the base vehicle (8.7 s in the sprint to 100 km/h). These simulations are seen in Figure 4. Illustrating that without electrical boost support, the acceleration time increases to 13.0 s, confirming that an e-Turbo is required. An increase in the E-machine power above 11 kW showed no significant reduction in response time (9.0 s to 9.4 s) as acceleration was limited by the electrical machine speed to 180000 min-1.
Regarding the potential to reduce the cost and complexity of the EGR circuit, the use of an HP-EGR-only strategy was investigated which would consist of recuperating excess exhaust gas energy, while controlling the VGT position to achieve the required back pressure to drive higher EGR rates at comparable boost pressure. The results showed, that including the LP-EGR path reduces the required electrical energy over the WLTC by about 30 percent, therefore both HP- and LP- EGR are used. As the PT-EATS volume was found to show only minor impacts on the fuel consumption, compared to the EGR strategy influence, Figure 5, the EATS volumes were chosen to fill the available package space. All the above variables were combined to create an optimised air path strategy. Combining LP and HP-EGR, with a comparatively small turbine and an 11 kW electric motor allows for the lowest possible boost requirement during transient driving conditions. The additional energy requirement for this configuration over a WLTC was approx. 52 Wh when omitting recuperation at the BSG or e-Turbo.
The electrical VGT turbocharger requires a dedicated control strategy to optimize the different operating states. For this concept configuration, the electric machine is mainly used for transient support during boost pressure build-up and recuperation during deceleration or in overrun operation. The conventional boost pressure control for the VGT was extended with an advanced model-based control for the power, respectively torque of the electric machine. In this approach the torque of the electric machine is calculated based on the difference between desired and actual turbine torque. An additional e-boost control factor is introduced to balance and adjust the responsiveness of the model-calculated torque demand to the e-machine against the electric energy consumption. The fuel consumption penalty and NOx engine-out emissions as a function of the e-boost control factor are shown, in Figure 6 for the WLTC.
When applying small e-boost control factors, the electric machine only supports during very high differences between desired and actual turbine torque, while for higher control factor values, the e-machine supports for smaller deltas in turbine torque. As such, the NOx engine-out emissions are reduced at higher e-boost control factor values, whereas the fuel consumption increases significantly in consequence of the increased electric power demand. These trends were combined to determine the target operation area.
The additional benefits of the 48V mild-hybrid system architecture shown in Figure 7 were evaluated. A 48V belt starter generator replaces the conventional 12V generator, a 48V battery with a capacity of 0.5 kWh, and the electrically supported electrical VGT turbocharger were integrated with the 12V on-board power supply provided via a bidirectional DC/DC converter. When optimizing the control of the electrical VGT turbocharger, a priority manager governs available power for the different consumers, based on the current state of the electric system. The simulation model uses a higher-level energy management strategy to ensure reliable supply for the on-board 12V network under all operating conditions and simultaneously maximizes the potential of the various 48V components to balance transient support during boost pressure build-up and recuperation potential at engine overrun operation and high enthalpy flow upstream turbine.
The balance of the electrical energy within the 48V system over the WLTC is shown in Figure 8. Recuperation takes place almost exclusively by the BSG, whereas the energy consumption is split in roughly equal parts between the supply of the consumers in the 12V network and to support the electrical boosting. As the recuperated energy exceeds the electrical energy consumption, approx. 30 percent is used to charge the 48V battery.
The second part of this paper in an upcoming magazin article will detail the PT–EATS system optimization and the overall system performance over key RDE cycles.
]]>Through the Paris Agreement, as well as the social policy goal of combating climate change, all sectors are committed to significantly reducing their CO2 emissions. The electric power supply sector is supposed to become entirely CO2 neutral by 2050. The transport sector is meant to reduce its carbon footprint by at least 80 percent as compared to 1990 – this despite an ever-increasing volume of transport. All conceivable climate-friendly solutions for passenger and goods transport also urgently need to be implemented. Some of these goals are reflected in the increasingly strict CO2 limits for newly registered vehicles in most countries. On December 17, 2018, the European Parliament and the Council of the European Union decided to reduce the fleet CO2 limits for newly registered vehicles again. CO2 emissions from cars are supposed to be reduced another 37.5 percent between 2021 and 2030. This translates to 59 g/km, which is equivalent to about 2.5 l of fossil fuel. When it comes to greenhouse gas reduction in the private transport sector in particular, one technical solution pops up more than most in the public and media debate: BEVs. The number of BEVs will indeed rise dramatically over the next decade. The starting level is still relatively low, however, with BEVs, plug-in vehicles, and range-extender vehicles currently making up roughly 2 percent of newly registered cars. The market penetration of BEVs depends heavily on various local legal parameters and government subsidies, and thus varies significantly in global terms.
The majority of all cars sold in 2030 (close to 90 percent) will still have a combustion engine for various reasons. The most frequent reasons cited for deciding not to buy an electric vehicle are the purchase price, the limited range, long charging times, and inadequate development of the charging infrastructure. In addition to this, only 2.5?–?5 percent of Europe’s vehicle fleet is replaced each year. As such, it will take several more years for BEVs and fuel cell vehicles to have significant market penetration. Relying solely on the growth of the electric fleet to achieve the ambitious CO2 targets is thus not an option. Instead, other effective technologies also need to be used. Using CO2-neutral synthetic fuels (e-fuels) can help in addition to electrifying powertrains and improving the efficiency of combustion engines.
It can be presumed that electrification will provide the largest contribution to CO2 reduction. In this context, electrification means not only pure electric vehicles, but also fuel cell vehicles, hybridizing combustion-powered powertrains, and powertrains with range extenders. An additional 24 percent reduction can be achieved by increasing efficiency through weight, friction, and enhanced aerodynamics as well as changing the modal split (shifting goods to rail). The remaining 31 percent needs to be covered by CO2-neutral fuels, as seen in Figure 2.
Looking at the energy situation in Europe and particularly in Germany, it is clear that the task of creating a system based 100 percent on renewable electricity poses a major challenge. Since renewable power (especially in Europe) is highly volatile and is not easy to store, grid expansion and necessary reserve capacities could involve very high investment costs in the future. The goal of using 100 percent renewable electric energy also means Germany would have to increase its production of renewable energy at least threefold compared to today’s production.
In addition to energy consumption, there is also significantly higher demand for energy for various industrial applications, the heating of buildings, and transport networks, currently total 2,600 TWh per year in Germany. In order to meet these needs using energy from renewable sources, Germany will have to start importing renewable energy on a large scale (Figure 3). Since some of the transmission paths are long, directly importing electric energy is only technically feasible to a certain extent, however. As a result, electric energy harnessed overseas using solar and wind power will need to be converted into chemical sources of energy by means of power-to-fuel. For regions with shorter distances between the production site and consumers, hydrogen or substitute natural gas could also be used as a carrier and transported via pipeline. Conversion into methanol or even Fischer-Tropsch products is a more sensible approach for more remote production facilities. Overall, Germany needs to import up to 29 percent of its energy requirement in the form of power-to-X (PtX) by 2050.
Using CO2-neutral sources of energy is the most efficient way to reduce its carbon footprint. As drop-in fuels, they can also reduce the carbon footprint of existing vehicle fleets. Due to their molecular structures, many prospective PtX fuels have different chemical and physical properties. The candidates that best meet the key criteria (energy density, fuel availability and established production paths, compatibility with the existing fleet) are Fischer-Tropsch fuels and longer-chain alcohols for diesel engines, as well as methanol-to-gasoline (MTG) and methanol for gasoline engines. It is possible to use hydroformylated Fischer-Tropsch fuels containing long and medium-chain alcohols to produce an e-fuel for diesel engines that is compatible with the current EN 590 standard and can thus be mixed into the existing fleet at any ratio. As shown in Figure 4, these fuels also allow for a significant reduction of soot and/or NOx.
Ethanol could be a highly promising candidate for gasoline engines. In 2018, some
110 million tons were synthesized and traded, primarily for the chemical industry. Due its very high knock resistance and good lean-burn characteristics, methanol can be used to significantly improve the efficiency of gasoline engines. As a result, e-fuels can be used to achieve similar tank-to-wheel efficiencies as in fuel cell vehicles. Figure 5 shows the increase in efficiency for engine measures implemented thus far and how the efficiency target of 50 percent could be achieved in the future.
Some countries, such as China, are massively promoting the use of methanol. In Europe, the methanol content in gasoline is currently limited to 3 percent v/v in EN 228, even though most fuel system materials are already certified up to 15 percent v/v. In addition to its direct use as fuel, methanol is also very well suited as a starting material for other fuels. For instance, the methanol-to-gasoline (MTG) process can be used to produce a gasoline-equivalent synthetic fuel that can also be mixed with conventional fuel in large quantities.
In the future, Germany will need to depend heavily on PtX imports. Cost will be the primary factor for the expansion of various technologies, however. Since local circumstances have a critical impact on the availability of renewable energies, the costs of synthesis also vary quite dramatically around the world. Figure 6 shows how greatly fuel production costs depend on the costs of power.
In many countries, e.g. in the Middle East and North Africa (MENA), the costs of synthesis will drop to below 1 euro/l diesel equivalent by 2030 due to low electricity rates. Although the potential for e-fuels has also been discussed outside of Europe, no large-scale PtX plan is currently in the works since legislation still does not acknowledge any CO2 reduction through e-fuels. As a result, market players still do not see a substantial enough business case to invest in e-fuels. A quick market introduction would be possible if one stakeholder were to profit from producing, marketing, or using e-fuels. A certificate trading system could also be introduced to allow carmakers to purchase CO2-neutral fuel and the corresponding certificates. By mixing it into the existing infrastructure, the fuel would be used by all customers.
The CO2 savings resulting from the use of e-fuels would then be counted towards the CO2 emissions of the manufacturer’s vehicle fleet. Another option would be to redesign the energy tax by lowering it on renewable sources of energy and gradually increasing the costs for CO2 emissions from fossil fuel combustion. The stakeholders addressed could be the petroleum industry or carmakers. This would yield a sustainable business model with the urgently needed investment security.
All technically feasible options will need to be used to achieve a quick reduction in CO2 emissions. However, the powertrain systems for heavy-load and long-distance vehicles cannot be electrified to the same extent as those for light commercial vehicles and cars. Goods transport will still need to rely on liquid or gas chemical sources of energy. As such, Europe will also rely on substantial imports of chemical sources of energy. The tank-to-wheel accounting currently gives a strong preference to electromobility – which will contribute enormously to lowering fleet CO2 emissions – over alternative technologies.
E-fuels have not been counted toward fleet emissions yet. Legislation thus requires urgent revision. There are various ways to make synthetic fuels more attractive, e.g. a tax on CO2 or carbon from fossil sources. Another option is to count e-fuels toward fleet emissions using a certificate trading system. Regardless of the political instrument used, synthetic fuel absolutely must be compatible with the existing fleet in order to quickly achieve market penetration.
]]>These solutions are based on many years of experience, for example in the development of innovative lighting systems for headlights or transparent OLEDs for rear light applications. The latest development also has the potential to permanently change the view of (and from) the car. The REALEYES Micro-Lens Array (MLA), a further development of the MLA wafer technology, allows for the production of extremely compact and light LED projectors out of plastic the size of a thimble. With their help, images or graphics, for example, can be projected from almost any angle onto any surface, without distorting. Even extremely flat angles of incidence are no problem for the MLA, which in combination with the compact structure allows for high flexibility during installation and reduces costs. Previous solutions mostly consist of projects with just a single lens and cannot execute diagonal projections with sharp contours.
FEV’s development is effective even with high contrast and homogeneous illumination. This opens up entirely new possible uses. On the one hand, these new graphics projections provide an innovative design effect, for example in the form of light carpets, which can already be seen in practice in precursors and offer the driver guidance and a pleasant environment. In mobility concepts, such as the fully-electric, 3-seater, SVEN, which FEV presented as a car-sharing mobility concept at this year’s IAA in Frankfurt am Main (Germany), the new MLA technology offers the possibility of further informative uses. For example, the user can be greeted by an external projection next to the rental car, or receive more information.
This new lighting technology not only offers advantages in terms of additional design aspects but also provides high functional benefits and increased safety, which will become standard in future, especially in electric vehicles. These move almost silently and therefore are hardly acoustically noticeable in their environment and can make other road users notice them with projections on the road surface ahead.
Scenarios are also conceivable in which projecting a pedestrian crossing in front of the vehicle informs pedestrians that the vehicle is stopping and that they can cross the road. Warnings transferred onto the road can notify cyclists that the door of a car parked on the roadside is opening. Also, when reversing or getting out of a parking space, similar visual information for road users could be possible.
Another focal point in the context of MLA technology is the 3D area. Whereas previous 3D processes for displays mostly relied on holography and auto stereoscopy, EDL’s patent is based on light field technology. It can be used to produce high-quality three-dimensional images that can be seen without the need for glasses or other aids.
With autostereoscopic technologies, the 3D effect disappears when you close one eye, because an individual image is projected in front of each eye and it is therefore only a 3D illusion. Another challenge is that the lens of the human eye does not have to be focused on the perceived depth of an object shown but on the distance of the display. This often leads to the viewer experiencing irritations and headaches. Such unpleasant effects do not occur with the light-field technology from EDL. Even with one eye closed, the viewer still perceives a physical, three-dimensional image, since the image points are projected into the space through rays of light, resulting in a real three-dimensional image.
The basis for this patented technology is also the MLA, which consists of numerous micro-lenses the size of a match head; on the surface of a square meter that is 253,000 lenses. These lenses are manufactured with an accuracy of under one micrometer, which is key to producing high-quality 3D displays. This manufacturing process is also part of EDL’s know-how. A special film is used as a storage medium, which is located behind the micro-lenses and is capable of storing large quantities of data. This is necessary, because each of the 253,000 lenses shows the full image, which deviates by a few thousandths from its neighboring lens, and each of these individual images is made up of 65,000 pixels. During manufacturing, the image information for the optic is delivered by an LED exposure unit patented by EDL, which ensures precise orientation. Color errors and distortions do not occur with this method.
The technology gives the viewer the feeling that the objects project up to a meter out of the display.This results in exciting fields of application for the automotive sector. In the vehicle cockpit of the future, it will be possible to create holographic operation elements such as a three-dimensional controller or switch projected virtually from the center console, which the driver can comfortably operate by hand and are captured by sensors.
Also, outside of the vehicle, this 3D development can prove advantageous – for example, integrated in the headlights. In this application case, the use of plastic optics produced by injection molding with the quality of glass optics resulted in entirely new design freedoms, leading to a headlight height of just 11 mm and therefore contributing to significant weight saving. In addition, at dusk the so-called “light-dark limit” could be illuminated on the film material behind the lenses, eliminating the need for visors, which such a narrow design would have made impossible anyway.
This 3D light know-how has already been used to develop vehicle tail lights for prototypes, in which the rear light optically projects from the tail light of the vehicle and is therefore perceived more quickly than with conventional tail lights. In the past, vehicle manufacturers have for example had to work with mirrors to achieve a similar depth effect, which is however nowhere near as pronounced. As a result, with this 3D light technology there is a clear safety benefit for road users with a significantly smaller installation space.
]]>Combined with the development of predictive and automated driving functions, further potentials can be tapped. The key factor for an actual reduction of the energy requirement under real driving conditions is a precise forecast of the future development of a traffic situation. This forecast can be based on a multitude of potential sources, such as sensor data, high-resolution maps, and vehicle communication, whereby all the data is fused into a comprehensive environmental model.
Based on the information from this model, the longitudinal guidance of the vehicle and the powertrain control can be optimized. In cooperation with the Institute for Combustion Engines of RWTH University Aachen, Germany, FEV has developed a function structure that is capable of using a multitude of potential data sources. This creates a solution space for predictive speed profile optimization. This speed profile can then be used in order to optimize the operation of torque distribution between the hybrid components.
The function structure was integrated in a hybrid prototype vehicle constructed jointly with DENSO. A robust, real-time model predictive control algorithm is used in order to optimize the longitudinal guidance of the vehicle.
The HYBex3 (”HYBrid power exchange 3 modes“) vehicle was developed in order to determine the impact of a cost-effective DHT transmission concept on the driveability of the vehicle and test it under real conditions. It was developed jointly with DENSO AUTOMOTIVE Germany. The base vehicle is a MINI Cooper with a turbocharged 100 kW three-cylinder combustion engine. The serial transmission was replaced with the hybrid transmission to be examined, which was specially developed for the application case. The powertrain topology is equivalent to a mixed hybrid equipped with two electric engines (EE) in a P2/P3 layout. The P2 machine is located between the electrohydraulically powered clutch and the two-stage spur gear component. The synchronization elements are also actuated electrohydraulically. The P3 machine is positioned at the transmission output and therefore has a fixed transmission ratio to the wheel.
Various operating modes can be represented with this DHT transmission. For purely electric driving, the combustion engine is stopped and the clutch is opened. Electric engine P2 can therefore be operated in both transmission stages. In addition to a high starting torque in the first gear, this enables a maximum vehicle speed of 140 km/h in the second gear.
In hybrid operation, serial or parallel driving is possible. In parallel operation, one of the two gear sets is engaged. In serial operation mode, the transmission is shifted to neutral. The combustion engine is then exclusively connected to electric engine P2 while electric engine P3 operates the wheels. All gear changes are synchronized entirely electrically, so that the friction clutch can remain closed even in hybrid operation. The serial operation in the low speed range and the parallel operation at higher speeds enable a significant increase of the system efficiency level.
The operating strategy provides for the combustion engine being operated at a very low dynamic and the implementation of fast load changes by the electric path. The transmission ratios enable a significant reduction of the rotational speed of the combustion engine, without compromising the overall dynamic of the powertrain. The operating strategy was optimized with a Design of Experiments. For this purpose, the parameters of the stop-start strategy of the combustion engine were optimized simultaneously with the parameters of the battery charging strategy. For the final parameterization, a compromise between the layouts for different driving cycles was selected.
The distribution of the torques of the two electric engines, both in parallel operation and in fully electric driving, is determined by an online optimization patented by FEV. The search algorithm varies the torque distribution until the energetically optimal case is found. In doing so, both the battery limits and the power limits of the electric engines are taken into account for the current situation.
The function structure developed for predictive longitudinal dynamic control is designed in such a way that a multitude of data sources, optimization routines, and powertrain structures can be represented in said function structure.
The first step is an aggregation and fusion of the available data into an environmental model, followed by a prediction of the traffic situation. This enables an optimization of the speed profile. On the basis of that, an acceleration control of the vehicle is carried out. The planned speed profile can also be used in order to adjust the charging status strategy. If the desired charging performance is determined, the torque distribution between the powertrain components is carried out on the basis of said performance and the wheel torque requirement.
The precise forecast of the current traffic situation requires the aggregation of all available data. This includes, for instance, RADAR sensors, LIDAR sensors, or optical cameras that traffic participants can identify with the help of image recognition techniques. Usually, these sensors indicate the type (passenger car, truck, pedestrian, etc.), the relative positions and, potentially, the relative speed of the detected objects.Further information can be obtained from the on-board navigation systems, which indicate speed limits, road gradients and curvatures as well as, potentially, intersection data for the most probable path of the vehicle via an “electronic horizon”. If the navigation system is connected to the internet, data on average speeds along the planned route and traffic jams can be provided.
Additional data can be obtained through the future connection of vehicles using 5G or ETSI ITS G5. This Vehicle-to-everything (V2X) communication should include, among other things, the positions, direction, and speeds of other vehicles, as well as the layout of intersections and the status of traffic light systems. The vehicle communication can therefore provide data that goes beyond the horizon detectable via on-board sensors.
Since the same object can therefore be detected multiple times by various data sources, the data aggregation must also include a functionality for data fusion. This is especially advantageous for hardware setups with different types of sensors, e.g. a RADAR sensor and camera sensor. The RADAR sensor can precisely define the distance to and the relative position of a vehicle driving ahead, but cannot determine the lateral position of the vehicle in relation to the road markings. In contrast, the camera sensor can only provide estimates regarding the relative speed and the distance, but can precisely determine whether the detected object is in the same lane as the vehicle under consideration. After the fusion of several data sources, an aggregated object list is created, which only contains valid and relevant data for all detected objects, and generates a corresponding environmental model.
Before an optimization of the vehicle trajectory can be carried out, there must be a forecast of the development of the current situation. This forecast is based on the relevant objects that the environmental model provides. The first step is the determination of the speed limit along the prediction horizon. Based on that and the current condition of detected vehicles driving ahead, the speed and position trajectory of these vehicles is forecast.
On the basis of this, a solution space is spread out in which the downstream optimization algorithm can operate. The function structure developed by FEV and the Institute for Combustion Engines enables the implementation of different algorithms to this end. Depending on the requirement, simple, rule-based approaches, as well as model predictive control or discrete dynamic programming methods can be represented.
To test the function structure, a real time-compatible model predictive control (MPC) was implemented in the rapid prototyping control unit of the HYBex3 concept vehicle and various test scenarios were carried out. In a first demonstration, the functionality and real-time compatibility of these scenarios for a predictive adjustment of the HYBex3 concept vehicle was proven. With an efficient implementation of the MPC using the qpOASES tool, an optimization of the speed curve for a horizon of 10 s can be carried out within less than 100 µs.
In the future, the modular design of the function structure can be used to expand the forecast horizon of the vehicle – for instance, with traffic lights ahead – or to represent predictive, automated driving functions such as Predictive Cruise Control (PCC).
]]>By today’s estimates, test scopes of 240 million to 16 billion kilometers of road* are needed to validate an automated driving function. However, it is not the quantity of tests that determines the maturity of a system, but the number of road traffic situations “experienced” in which the algorithms have to actively make a decision – for example, during an overtaking maneuver on the highway.
In this regard, the V2I (Vehicle-to-Infrastructure) data management system established by FEV is an efficient solution for the development and validation of such driving functions. This is because aside from the duration and number of test drives, the quantities of data obtained are also a major challenge with regard to the validation. The sensor set installed in the vehicle, consisting of cameras, lidar (light detection and ranging), and radar (radio detection and ranging), quickly generates up to 40 terabytes of data in a single day.
That is precisely what the data management solution from FEV deals with. First, a networked data logger developed in-house takes over the collection of selected vehicle signals and sends them to a back-end in real time during the test drive. FEV once again cooperated successfully with Microsoft for this. With the combination of Azure Cloud Microsoft products and the IOT hub responsible for the data transfer, FEV was able to count on an established, high-performance tool chain. The sent vehicle data is consolidated in the cloud, while algorithms analyze these signals in regards to relevant scenarios. It is therefore possible to send feedback to the relevant engineers even during test drives, and to flexibly coordinate entire fleets according to a predefined plan.
A standardized time stamp also significantly simplifies the cleaning and preparation of all vehicle data. Not least, this scenario-based pre-filtering also enables cost-efficient data storage in the cloud. Only previously-detected data packets or scenarios are loaded into the cloud hot storage, which is the layer with the highest available computing power and access management. Less important sections are saved in lower performance cloud areas that are consequently more affordable.
As an integration and development partner in series production projects of various automotive manufacturers, the efficient assessment and validation of sensor data quickly proved its worth for FEV and its clients. To minimize the general testing time on real streets and the associated costs, the development service provider is increasingly transferring significant test scopes to simulation and laboratory environments.
The data-logger solution, in combination with FEV’s own cloud-based labeling software, is a significant milestone for the construction of a holistic development environment for ADAS/AD environments. The efficient preparation of the data using automated recognition and classification according to driving situation is the basis for all other process steps in this regard.
While the driver assistance systems in series production today are still based on predefined rules, in the future, FEV believes that this will also be possible with the use of machine learning. FEV’s goal is to let artificial intelligence handle even the most complex of situations and accurately anticipate the behavior of road users.
The cooperation with Microsoft is an important component of this. Interdisciplinary collaboration between sections of the automotive industry and IT is enabling groundbreaking, cross-company innovations to be established, which offer critical development benefits. At this year’s IAA in Frankfurt, the German Chancellor and visitors had the chance to view the results of the cooperation at the
Microsoft booth.
Mobility is a determining factor for the quality of life in urban areas. The expected doubling of the urban passenger mobility demand by 2050 will push conventional ground based transportation to their limits. Moreover, their enhancement is limited due to large investments, footprints, and lead-times required. Metropolitan areas and cities will consequently face significant challenges with regards to pollution, noise, and congestion.
The sky however, has been successfully used for safe and time-efficient long-haul transportation for decades. Already today, conventional helicopters operate as air taxis in cities like New York City. An 8-minute flight from JFK Airport to Lower Manhattan costs around $200 USD per passenger using the Uber Copter Air Taxi Service. Also, Blade offers an Airport Pass for an annual fee of $295 USD, with which each flight between Manhattan and NYC airports costing $145 USD. Comparing this with ground transportation, the same trip costs $55 USD for a regular taxi and $120 to $180 USD for a more comfortable Uber Black Service, but takes 55 to 100 minutes.
The high (operational) costs of a helicopter are the key driver behind the high fares. Next to this, noise emissions limit the uptake of current air taxi services. In the recent past, start-ups and established aviation companies developed new disruptive aircraft concepts: electric Vertical Take-Off and Landing (eVTOL) capable aircraft equipped with Distributed Electric Propulsion (DEP). The number of eVTOL related patents has vastly increased in the last years, with USA, China, and Germany being at the forefront. The enabler for eVTOL technology is based on the recent technology improvements in battery technology, electric motors, and automation technology, leading to several advantages compared to conventional helicopters: They promise a safer, quieter, and significantly less expensive operation. With the availability of eVTOL technology, Uber forecasts significantly less than $5 USD per passenger mile for their Uber Air Service in the near term.
Due to the advantages of eVTOL aircraft, a high growth of the eVTOL market is expected. With FEV Consulting’s background from a major near-term Urban Air Mobility (UAM) program for a megacity’s transport authority and their deep eVTOL industry insights, the company forecasted the global eVTOL fleet size through 2040. The projection takes several parameters such as the economic attractiveness of eVTOL air taxis, environmental conditions, underlying regulations, policies, and infrastructure into account. Furthermore, cultural probability of technology adaption and the number of expected, credible eVTOL manufacturers were considered.
The market of eVTOL concepts is broadly diversified, with a common set of technologies such as electric propulsion. More than 80 start-ups and established aircraft manufacturers are currently developing over one hundred eVTOL aircraft concepts. Having extensively reviewed these concepts, FEV Consulting expects that less than 20 percent are suitable for aerial ride sharing and are developed by credible players which have the capability to drive its concept through full development and certification into operation. Different use-cases are a key driver behind the broad conceptual diversification of the eVTOL aircraft landscape. The main differentiator is the aircraft architecture with the related propulsion concept: It can be distinguished between the multirotor, the lift & cruise and the tilt rotor/wing architecture. While there are also differences in the energy source, i.e. pure electric and hybrid systems, the following paragraphs focus on the electric motor.
Performance related requirements differ between the architecture concepts due to different cruise speeds and Maximum Take-Off Weight (MTOW) requirements, but also due to the number of electric motors. Power and torque densities along with the e-motors’ efficiencies are very important to aircraft due to their direct effect on the overall efficiency, range, and consequently on the overall mission suitability. Figure 5 provides an overview of the power density of electric motor concepts from suppliers with aviation activities compared to aviation certified piston engine or turbine applications. It shows why distributed electric propulsion becomes so popular for eVTOL, but is also attractive for small general aviation applications, since state-of-the-art electric motors can achieve weight savings compared to piston engines.
In addition, electric motors for aviation applications must be highly reliable because malfunctions can directly lead to flight critical emergency situations. Against the background of the operational concept, high availability and long maintenance intervals are required. Since the aircraft are lightweight designs mainly based on composites, the Noise Vibration Harshness (NVH) of electric motors should be at a minimum to avoid transferred vibrations to the fuselage and structural components. Using electric motors for these kinds of new aircraft concepts instead of complex turbines, could offer an opportunity for automotive players with activities in the electrification of powertrains.
The aerospace industry is characterized by low quantities and low economies of scale compared to the automotive industry with its cost-efficient mass production. The top-selling Airbus A320 was sold 417 times in 2018, which is less than a tenth of the sales volume a BMW 3 series has per week with 366,475 units in 2018.
Key components such as the propulsion system are flight critical and can lead to emergency situations, catastrophic events, and high liability claims. Therefore, such products must comply to the certification specifications defined by regulatory authorities such as the Federal Aviation Administration (FAA) of the United States of America or the European Aviation Safety Agency (EASA). The certification requires among others, extensive testing, validation, and related detailed documentation and reports. Furthermore, a certificate approving the manufacturing of the type certified product is required and all produced components must be highly traceable. These certification and compliance requirements lead to the high development and industrialization effort which needs to be allocated to the low quantities.
On the contrary, the automotive market is characterized by its high sales numbers and the high competition which demands for a cost-efficient mass production and lean organization and development processes. The effort for obtaining a type approval for a car is different to aviation, but the new eVTOL aircraft are also less complex compared to commercial civil aviation aircraft like the A320. Consequently, the capabilities of the automotive industry can help to reduce the costs, make air taxi fares more affordable for a broader public and can contribute to the expected market growth of the eVTOL industry.
At first, automotive players might perceive the requirements for certification as a high entry barrier. However, the supplier base for technologies, such as batteries and electric motors is less established compared to conventional aviation products. The profound experience automotive players already have from their products being used by end-customers on the road should not be underestimated since they provide real-world durability data. The acquired knowledge might help to establish a high level of confidence for respective authorities to certify products from new players. In addition, automotive players develop their products according to (automotive) ISO and SAE standards, which are similar to related standards of the aviation industry. Furthermore, the automotive industry is well experienced regarding supply chain, logistics, and production processes which will be required for a higher output compared to today’s conventional aviation industry. Consequently, there might be a gap, but not a cold start to bring automotive products into the aviation market.
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