On the test route, the technology of the future is still embedded in the body of a series-produced Audi Q7. What’s special is inside: a new chassis and the new powertrain of the quattro with e-tron technology that consists of two electric motors. These so-called technology demonstratorsdemonstrator allow tests to be performed with less camouflage. The chassis and powertrain are based on the Audi e-tron quattro concept which was presented at the IAA in 2015 and which serves as a basis for Audi’s forthcoming electric series vehicles. The technology has been tested for months, not only on the Audi test routes around Ingolstadt, but all over the world, in every driving situation: on ice, in the desert, in the mountains and in the city. Dr Michael Wein, project manager for quattro with e-tron technology, was recently driving the vehicle with colleagues in Lapland, where they exposed the car to extreme cold and ice. “We’re very satisfied with the latest tests. We’re coming round onto the home straight now,” says Wein. When talking to him, you can see that he is looking forward to the premiere of the first quattro with e-tron technology.
Banked corners, wet ground, steep inclines – the chassis and powertrain of the new quattro with e-tron technology demonstrates its abilities once again on the off-road testing ground at Neuburg an der Donau in Upper Bavaria.
At the testing ground, where other vehicles might struggle, this all-wheel drive system masters the obstacle course’s banked curves, see-saws, fords, tree-trunks and extreme slopes with ease and also coped with the challenges of the dynamic surface. One wheel over a precipice, the other almost down on its rims – in persistent rains and squalls, it showed endurance even in extreme situations. Sitting on the passenger seat, Wein monitors data from the chassis on his laptop. He doesn’t flinch, even in situations which normal drivers might consider precarious. He is confident that the chassis can handle any kind of driving situations.
The success of today’s tests is a result of decades of collaboration between various departments at Audi. “Some challenges are so new and so complex that we have to collaborate much more closely than before to find solutions,” says Moritz Reiff, project coordinator for drive functions of the quattro with e-tron technology. He is evaluating the tests together with Michael Wein. Instead of a mechanical connection involving a prop shaft and differential, this is the first Audi to have two motors connected by software, which produces entirely new challenges. “It’s an interplay between mechanics, mechatronics and an increasing amount of software,” explains Reiff. Audi can build on 40 years of experience in developing its all-wheel drive system. To explain, Wein goes briefly into the history: the first series-produced Audi to feature quattro was driven by an open differential, which was later replaced by a self-locking differential. The later mechatronic all-wheel drive system with a multi-plate clutch was already using special software. “In that respect, the quattro with e-tron technology is based on software which has already proven itself in predecessor vehicles,” says Wein. However, this is the first time that the two axles have been controlled entirely separately using two electric motors and software. The software calculates how much force is needed to drive each axle, and tells the motor in every driving situation how much force it should produce. “That happens every 10 milliseconds,” explains Wein.
To do this, the software evaluates over 150 input signals from the steering, the accelerator pedal, assistance systems and other sensors, 100 times a second. “It sounds complicated. Because we no longer have to move a clutch, but only electrons, it’s much quicker than in conventional motors,” says Reiff. “The motors respond in just a few milliseconds.” This is a learning system: by evaluating, the software can differentiate between dynamic and passive drivers, and make decisions tailored to the driver’s profile in order to help. But control remains firmly with the driver. The developers’ aim has been to make the vehicle as safe as possible to drive in any situation.
And when it comes to efficiency, quattro once again offers new possibilities thanks to its two electric motors. While driving – on the motorway, for instance – the drive controller distributes energy to both axles, depending on which mix is more economical. “We have full freedom: for example, 70% can go to the front, 30% to the back – or the other way round,” says Reiff. Reclaiming kinetic energy when decelerating is also more effective. “Because braking force is distributed efficiently between the front and rear axles, we can reclaim more energy than before,” continues Reiff. “Tests have shown that it isn’t just aerodynamics that play a key role in terms of range, but that we can generate around 30% of the range using recuperation.”
“The quattro with e-tron technology offers better traction, longer range and improved performance. Electromobility and quattro go together wonderfully.”
Because the concept no longer involves a prop shaft, passive components weigh less, in favour of active components such as the two electric motors. This creates more space in the underbody for a powerful battery. The combination of recuperation, quattro drive and electric generators has allowed developers to extend the range to up to 500 kilometres in the course of testing. The experts at the testing ground agree: “The quattro with e-tron technology offers better traction, longer range and improved performance. Electromobility and quattro go together wonderfully.”