Audi meets University:
the mobility of tomorrow

Gentlemen, how will we drive in future? Researchers and development engineers from Audi and the Technische Universität München (Technical University of Munich) talk about the mobility of tomorrow. They agree on one thing – we are currently experiencing the greatest upheaval in the history of the automobile, in the form of a gentle revolution.

Expert forum (l. to r.): Peter Pilgram (Audi), Prof. Dieter Gerling (Hochschule der Bundeswehr), Peter Kunsch (Audi), Siegfried Pint (Audi), Andreas Schulze (TUM), Matthias Kerler (TUM) and Prof. Markus Lienkamp (TUM).
AUDI FUTURE IDEAS

Gentlemen, how will we be driving in 2025?

Lienkamp: Over distances of around 200 kilometers, I assume that battery-electric drive will be less expensive than conventional drives from an overall cost perspective.

Pint: Electric drive is establishing itself more and more. By 2025, we’ll be offering a wide array of plug-in hybrids and battery-electric cars in addition to gasoline and diesel engines. The range is becoming increasingly diverse, which means we have to maintain clear control of the complexity. High-voltage hybrids without a battery-electric component are likely to be less interesting. Mild hybrids with 48 and 12 volts are technically less complicated and are the better solution in terms of cost. I also see fuel-cell technology playing a role, albeit in smaller numbers.

 

At what pace do you see electromobility ­establishing itself in Germany?

Lienkamp: I think the target of one million electric cars by 2020 set by the federal government is a little overambitious. But I reckon the costs for electric cars will fall to the extent that, by 2020 or 2022, they will have reached the level of cars with classic drives. By then, we’ll have achieved battery prices of 120 euros per kilowatt hour, which makes them economically viable.

Peter Pilgram, High-Voltage Battery Development.

Does that tie in with Audi’s expectations?

Pilgram: I hope we’ll get there sooner. We want to put our battery-driven SUV based on the e-tron quattro concept into volume production in 2018, and costs obviously play a major role.

 

What cell technology and which cell format will be used in future?

Kerler: We can see that the very large-format cells don’t seem to be the right approach. Format is a matter of application that has to be decided individually.

Pilgram: We’ve found a good solution with our cell modules. They are standardized cuboid casings a little smaller than a shoe box, which we can fill with pouch cells or prismatic cells. We have a solution for round cells, too. Thanks to these modules, we’re able to accommodate new developments and get them into a car quickly. We’ll produce the batteries for our vehicles in Europe and we’re currently in the process of bringing cell production to Europe, too.

Matthias Kerler is a research associate responsible for the battery storage function within the Electric Vehicle Components Research Group at TU München.

After lithium-ion, which technology has the best chances?

Lienkamp: Over the last 20 years, there has been a seven percent improvement in energy densityyear-on-year. Many experts expect this trend to continue over the next five to eight years.

Pilgram: That’s in line with our developments and expectations. In four years, we’ve gone from a 22 Ah to a 37 Ah cell. The lithium-ion system, as it stands today, certainly has a positive future ahead of it. The new technologies are not yet as far advanced – we won’t see any of them in a vehicle before 2025.

Lienkamp: I could see a further 20 percent improvement if the automotive industry didn’t spend three or four years testing the cells before putting them into series production …

Pint: We’re introducing electromobility in a manner that ensures it works smoothly and safely. There could be no greater obstacle than a defect that, in the worst case scenario, could even be dangerous. That’s why I’m a great believer in a low-risk strategy – although I’m well aware that we have to adjust our development times accordingly and, ultimately, also dampen the euphoria somewhat.

Most of the time, rapid charging is about topping up sufficient energy for the rest of the journey. That’s not a problem for the battery. (Matthias Kerler)

I think the lithium-ion system, as we know it today, certainly has a positive future ahead of it. The new technologies are not yet as far forward – we won’t see any of them in a vehicle ­before 2025. (Peter Pilgram)

Will customers accept charging times at all, ­considering the status quo enables them to fill up their car in just a few minutes?

Lienkamp: Just to play devil’s advocate for a moment: Right now, you need five minutes to fill up including payment, and you end up with dirty hands in the process. With an electric car, you don’t have to do that anymore and the car is fully charged every morning. I’d like to turn the discussion toward the positive. We always act like the electric car has a problem. Mr. Gerling, how often do you charge your car?

Gerling: I’ve been driving an electric car for a good 18 months now and have already covered around 50,000 kilometers with it. And I spend less time charging it than I did before filling up with fuel. I obviously need a bit more time for longer distances, but the overall effort is less than before.

Lienkamp: Our faculty has an electric Golf. It’s plugged in all the time and we can just drive off with it whenever we need to. It’s a lot less work for us than driving to the fuel station, which is five kilometers away.

 

How much range do electric cars need?

Pint: Even today, it’s unusual for a customer to drive more than 300 kilometers per day. However, the desire for unrestricted mobility is very strong, which is why we’ll be offering the e-tron quattro with a battery-electric range of more than 500 kilometers. In a normal situation, the customer simply recharges the car overnight in their garage at home and the full range is ready and waiting for them every morning.

Lienkamp: If we consider the batteries at cell level, we’re currently at an energy density of 250 Wh per kilo­gram. Once we achieve 300 Wh/kg, we won’t have much of a weight or packaging issue any more, even at a range of around 300 kilometers. I think these are realistic, customer-friendly targets.

Gerling: We mustn’t assume that 100 percent of car drivers will switch to electromobility right away. There will still be those who want to cover the distance from Hamburg to Munich in one go, but the percentage is relatively low. And in my opinion, what can be achieved today with electromobility already covers the majority of customer expectations. The few percent that it doesn’t cover will follow eventually.

Pilgram: The average daily driving distances can already be covered today with our e-tron plug-in hybrids on battery power alone. And in 2018 there will be a 150 kW rapid charging network for covering long distances with electric cars. This allows you to quickly add more range after a few hundred kilometers – when it’s time to take a break anyway. I reckon there are plenty of compelling arguments.

Kerler: Most of the time there won’t be a need for a full charge, just sufficient energy for the rest of the journey. That’s quickly dealt with and not a problem for the battery, even with high charging power. We conducted a survey and the results showed that the majority of owners of electric vehicles not suitable for rapid charging would want such a feature and would have it installed retrospectively or would only buy a new electric vehicle that had such a feature.

Professor Dieter Gerling, Head of the Institute of Electric Drive Technology at the Bundeswehruniversität München (Military University of Munich). Main subject – drive technology.

Can electric cars and plug-in hybrids play an active role in the energy transition?

Lienkamp: The appealing thing about e-mobility is that electric cars will automatically keep getting cleaner, because the proportion of eco-electricity in the grid is growing all the time. This trend has to continue, and we’ll be ramping up electromobility in parallel.

What happens to the batteries at the end of the vehicle life?

Pilgram: We are designing our battery systems to last a whole vehicle life, and providing a generous warranty. It will be ten to 15 years before customers find themselves handing back a vehicle or a battery. And the batteries will still be usable even then. For instance, they can be used statically in storage depots as buffers for handling load spikes in the electricity grid.

Lienkamp: At the moment, pumped-storage hydropower plants cost 250 euros per kWh of installed capacity. If we can get battery costs into the ballpark we just talked about, we’ll be at less than that, which would make that kind of application completely viable.

Siegfried Pint, Head of Development Electric Drives, Audi.
We’re introducing ­electro­mobility in a manner that ensures it works smoothly and safely. I’m a great believer in a low-risk strategy – although I’m well aware that we have to adjust our development times accordingly. (Siegfried Pint)

How important is 48-volt technology to the realization of a cost-effective ­electrification base?

Pint: It’s an important topic. Even with 12 volts, we’ll facilitate a base level of hybridization and bring it to market in 2017. 48-volt technology obviously gives us considerably more possibilities. Incidentally, Audi will present its first production model with 48 volts in just a few months time. The benefit is that we can realize the electric boost function, which gives us amazing improvements in sprint performance. Customers will love it. On top of that there are also comfort and efficiency functions – such as air conditioning without using the main drive, or the belt-driven starter generator, which enables extremely comfortable gliding and a smooth start/stop function. And we’ll also integrate the 48-volt system directly into the driveline.

Gerling: We’re in the process of demonstrating battery-electric driving with 300 kW of power and 48 volts. The layout we have at the moment is certainly more efficient and cost-effective than a high-voltage drive.

Pint: But you’re working with currents of 7,000 amperes – and you believe that will be less expensive?

Gerling: Yes, it will be less expensive in all the individual components. We have a first functional example ready to run in the lab. I think it can present a way forward.

Pint: I find this approach extremely interesting. You can see just how diverse the possibilities are.

Peter Kunsch, Head of Predevelopment Landing gear, Audi.

What other systems benefit from 48 volts?

Kunsch: We have a lot to gain in chassis engineering. Thanks to 48 volts, we can develop things like regenerative running gear. A 12-volt network can’t transmit the necessary amounts of energy. We even have a research project that replaces the damper with an electric motor and generates energy with every movement. The worse the road conditions … but we still prefer good roads, of course. We will soon be showing our first series production car with electromechanical roll stabilization. Small electric motors twist the anti-roll bar to actively support the bodyshell when cornering. It’s so fast and so precise that it delivers a whole new level of handling, even for big, high vehicles. And the customer has a clear added value – he feels it even without 20 years experience as a vehicle test driver.

And what other possibilities are there?

Kunsch: There are brake-by-wire systems, for instance, that deliver excellent pedal feedback. This is important if most of the braking is to be done via the electric motors rather than the brake discs.

Schultze: Extensively decoupled brake systems are definitely a trend. I think it soon won’t be necessary to have any hydraulic lines running through the vehicle at all. In terms of handling, torque vectoring systems will also continue to establish themselves. At the Tech­nische Universität München, we’ve already shown a system of this type, which is activated by electrical power alone and delivers a significant improvement in stability. One usage scenario would be to combine this with low-rolling-resistance tires – less friction with the same handling characteristics.

Pint: There was a very interesting execution on display at the Frankfurt Motor Show – the Audi e-tron quattro concept with two electric motors at the rear axle. This can work directly with the traction drives to generate an enormous moment differential, way in excess of the torque-vectoring potential offered by clutch-based systems. The torque can be distributed super-precisely in just a few milliseconds, which we can use to benefit safety on the one hand and driving fun on the other. Torque vectoring makes it possible to offer the driver a very light, agile handling feel with a vehicle that tends to be rather on the heavy side.

Schultze: Electric motors, of course, have extremely fast response characteristics …

Andreas Schultze, research associate, Team Leader of the Handling Research Group in the Vehicle Technology Faculty at TU München.

Electromobility also offers driving without engine noise. What is your opinion on artificial sound?

Gerling: Over the past century, human beings have
gotten used to certain noises – but that’s not a law of nature or anything. It’s quite pleasant to travel quietly.

Pint: Electromobility, the new connectivity products and the possibility of piloted driving all give rise to an extremely pleasant and enjoyable mobility experience. In my opinion, the car is becoming a whole new living space, like a kind of retreat. And electric drive is ideal for this. We don’t want to influence that with artificial sound.

Kerler: I have a little anecdote on this. I gave my godchild a toy car and have managed to teach him that it goes “ssssst” instead of “vroom vroom”. I like the purring of power electronics and electric motors. It sounds so futuristic.

Professor Markus Lienkamp, Head of the Vehicle Technology Faculty at TU München. For the past six years, his focus has been primarily on complete vehicle design.
Over distances of around 200 kilometers, battery-electric drive will probably be less ­expensive than conventional drives from an overall cost perspective. (Prof. Markus Lienkamp)

I have one more request. Would you mind rounding off this discussion with your views on what your ideal electric car would be?

Lienkamp: Definitely a second car, a two-seater, low-cost yet agile.

Gerling: I’m already driving my ideal electric car, although I’m not telling you what brand it is.

With 48 volts we can develop completely new functions that deliver a whole new level of handling for big cars, too. And the customer has an added value he can feel right away. (Peter Kunsch)

Kerler: For a start, I’d like 300 km of range – maybe 250 km in winter. And please, please – no fancy, elaborate design! I don’t mind the car looking electric somehow – but not ugly.

Schultze: I want something that’s all things to all men, which I’ve yet to find among conventionally powered cars. That means plenty of power, with a good chassis and handling. And a high range would obviously be good, too.

Pilgram: 300 km range to replace my main car, rapid-charging capability and four seats for the whole family.

Kunsch: My ideal electric car is a second car – sporty, quattro, with a range of at least 150 km.

Pint: My ideal electric vehicle is coming in 2018 with the production version of the Audi e-tron quattro concept. At 500 km in the NEDC, the range is already very high; and with its three-motor drive concept, it has very dynamic performance. Thanks to its functionality, it’s already more than suitable as a main car. But there’s another electric vehicle I’d like – a motorcycle. Motor­bikes are ideally suited to electrification – low distances and a massive global market.

ELECTRIC CARS OF TU MÜNCHEN

In terms of handling, torque vectoring systems will also continue to establish themselves – of the type we’ve already shown at the TU München. (Andreas Schultze)

The Mute, a battery-electric research vehicle with two seats, was created at TU München between 2010 and 2012. It weighs just 500 kilograms and brings together innovations from 20 faculties. The Visio.M research project builds on these findings.

Between 2010 and 2012, TU München developed a city electric car known as the Mute under the leadership of Professor Markus Lienkamp. The two-seater is 3.55 me­ters long, has a bodyshell made from CFRP (carbon fiber reinforced plastic) and aluminum and a curb weight of just 500 kilograms. An electric motor with 15 kW accelerates it to a top speed of 120 km/h. The publicly acclaimed prototype has a range of more than 100 kilometers. According to calculations by TU München, the Mute shouldn’t cost any more to produce than a conventional small car.

A second, publicly funded vehicle project based on the Mute was established in 2014. The Visio.M has been further developed in many technical aspects.
 
 
Johannes Köbler, Oliver Strohbach (text), Ulrike Myrzik (photos)

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