Der Antrieb von morgen 2019

Our way of life is changing rapidly und radically forced by four global megatrends: Climate change, Globalization, Urbanization and Digitalization.

In developing the Audi e-tron (Figure 1) Audi is going down entirely new roads with its in-house development of electric axle drives, high-voltage storage systems and charging systems. Featuring one drive on each axle, the full electric drivetrain embodies Audi’s core competency – the quattro drive – in a new and impressive way.

Electric motors, power electronics and axle gears incorporating a high degree of component sharing form the basis for a completely new final drive kit. The electric axle drives are manufactured at Audi’s own engine/electric motor plant by Audi Hungaria.

The 95 kWh 400 V high-voltage storage system is likewise an Audi in-house development. To create a 360° system offer, numerous services and wide-ranging charging options were developed with up to 150 kW charging power based on DC quick-charging.

How does the powertrain of tomorrow look like? This question has driven the automobile industry since its existence. But it seems to get more and more difficult to answer it. One of the reasons for this is the broad diversification of the powertrain and the question which one is optimal. But this is not a novel issue for the automobile industry. Back to its beginning in the early 20^th century in the US, the center of the automobile industry, almost 40 % of the vehicles were electrically driven, 40 % of the vehicles had a steam engine and only 20 % of the vehicles had a combustion engine.

The purist and award winning vehicle demonstrator CULT (Cars Ultra Light Technologies) of Magna Steyr was equipped with an innovative 3-cylinder 600 ccm compressed natural gas (CNG) engine with direct CNG injection, micro hybridization, automated transmission and achieved approximately 60 g CO₂/km in the European test cycle. The results achieved with this configuration comprising a vehicle weight 680 kg have proven that it is possible to achieve lower CO₂ emissions compared to an electric driven vehicle based on the European electricity generation mix (~80 g CO₂/km).

The reduction of CO₂ emissions has been an important topic for innovation in the automotive industry already for the last decade. However, further improvements in powertrain efficiency and advances in lightweight construction and aerodynamics will each play a key role in efforts to meet the stricter future CO₂ limits. Especially with the approach of the EU environmental ministers to lower the transport-related CO₂ emissions by 37.5% from 2030 onwards in comparison to 2021 the average figure amounts on a fleet-average base to only ~ 59 g/km under WLTC conditions.

Obvious changes in the world‘s climate make action necessary. Today’s transport sector, including air, rail, marine, and road transport and traffic, is responsible for almost a quarter of the world’s CO2 emissions. The internal combustion engine is the dominant propulsion system, and the burning of fossil fuels not only results in CO2 emissions but also NOx and other pollutants harmful to all living beings.

Never before have the challenges for future propulsion systems been more demanding than these days. It is important to consider the very complex goals in terms of primary functionality, environmental compatibility and cost efficiency to a balanced extent. Based on a detailed analysis the 48V technology turned out as the most effective approach considering the trade-off between CO₂ and cost (Figure 1).

In 2015, the transport sector was responsible for 204 million tonnes of CO2 or 27.6% of energy-related CO2 emissions in Germany (based on [1]). In contrast to the energy sector, emissions from transport have been at a constant level since 1990 [2]. Even though the transport sector is stagnating in this respect, moving away from the ambitious greenhouse gas (GHG) reduction targets of 40% by 2040 and 80-95% by 2050 compared to 1990 [3] is not an option in view of the Paris Climate Agreement. Against this background, the question about the role of electric vehicles (EV) to meet climate targets arises.

Electromobility is ruled by a strong political will of implementation, because it may contribute the ambitious goals in climate protection and energy issues of the European Union and Germany. Furthermore a significant reduction of the CO₂ emissions in traffic, the improvement of the air quality as well as noise reduction in urban and suburban metropolitan areas is expected.

The strengthening of enforcement of environmental laws and regulations has led to an acceleration in the worldwide switch to electrically-powered vehicles, commonly referred to as the “EV shift”, and consequently has escalated the importance of rechargeable batteries used as drive power for EVs. Lithium-ion batteries (LiBs), the most representative in automotive use because of their light weight, high energy and high power density, need a battery management system (EMS) to accurately estimate the condition of the battery, especially state of charge (SOC) and state of health (SOH) in order to ensure efficient, reliable and safe performance. In comparison with the number of research reports on SOC, there are relatively few reports on SOH, because establishing the correspondence between the characteristic parameters and battery health is considerably difficult. This paper focuses on synchronous estimation methods for SOC and SOH, takes a close look at their general principles and scope of application for an in-vehicle unit, then performs experimental evaluation through case study of LiBs with different deterioration properties.

To reduce the local CO₂ emission of vehicles, alternative zero emission propulsions systems can be used. The most prominent being battery electric vehicles. But the two major drawbacks of long refuelling times and comparably low driving ranges can be addressed by using a range extender.

In the last decade, the development of cleaner vehicles with higher fuel economy and lower emissions is becoming a mainstream in automotive industry because of the aggravation of oil crisis, public concerns on environmental protection, and stringent regulations on CO₂ and pollutant emissions. Thus, the automotive industry regards hybridization and electrification of powertrain as a solution to reduce fuel consumption and pollutant emissions.

The increased occurrence of meteorological disasters, as an effect of climate change, but also health hazards due to bad air quality in urban areas, resulted in stricter limits for pollutant and greenhouse gas emissions of passenger cars. Concerning the containment of global warming to 2 °C above the average temperature before industrialization, the European legislator demands the automotive industry to assume responsibility to reduce the CO₂ emissions in road transport. For new passenger cars the fleet-averaged CO₂ emission limit was set to 95 g/km for the year 2020 [1].

Motivated by the ongoing urbanization megatrend, a vision for future urban mobility can be derived from the main problems like space scarcity, congestion, vehicle emissions and road safety, which most major cities have in common. Urban transportation planning shifts the priority from maintaining free flowing traffic towards facilitating access to destinations. Instead of improving conditions for car travel, e.g. by providing more lanes, the Avoid-Shift-Improve (A-S-I) [1] approach first seeks to reduce the need for travel, then promotes shifting trips towards non-car modes like public transit, bicycle or walking, and considers measures which improve efficiency within the modes, i.e. electrification.