Audi Goes Electric
The Audi A8, the flagship of the Ingolstadt-based brand’s lineup, has launched in its fourth iteration, and it marks a change in the powertrain approach that has long been taken by Audi.
The car is being equipped, for the first time, with an electrified drive—as standard.
This is a mild hybrid configuration that is based off of a 3.0-liter, turbocharged V6. The engine (and we’re using the German configuration information here because the U.S. numbers aren’t yet available at the time of this writing) produces 340 hp at from 5,000 to 6,400 rpm and 368.8 lb-ft of torque at from 1,370 to 4,500 rpm. The engine is mated with an eight-speed tiptronic automatic transmission.
The mild hybrid system consists of two primary elements, a water-cooled 48-volt belt alternator starter (BAS) and a lithium-ion battery system that is located under the floor of the trunk. The primary electrical system for the A8 is 48-volts; there is a DC/DC converter to step down the power for applications that are based on the 12-volt electrical system.
In terms of the performance of the mild-hybrid system it allows the engine to be shut off when the vehicle is traveling at between 34.2 and 99.4 mph. The A8 will coast for up to 40 seconds before the engine is restarted. Or, the engine will fire immediately upon the driver touching the throttle. The 48-volt system also permits start/stop operation from a speed of 13.7 mph.
One of the most-notable features—as it is said to be a world’s first—of the A8 is what the company calls “AI traffic jam pilot.” It is said to be SAE Level 3 autonomous driving capable.
According to SAE: “Level 3—Conditional Automation: The driving mode-specific performance by an Automated Driving System of all aspects of the dynamic driving task with the expectation that the human driver will respond appropriately to a request to intervene.”
So the task of the driver, when the system is activated, is not to constantly monitor what’s occurring, but to be able to take control of the vehicle when required.
The Audi system works on divided highways (when there is a physical barrier between the two directions of travel) and at speeds of 37.3 mph (60 kph).
The real purpose of the AI traffic jam pilot is simply to provide relief when, as the name implies, the car is in a traffic jam.
But what, as this is about powertrain, is an autonomous driving discussion doing here?
Simple. The A8 is arrayed with a suite of sensors. There are a laser scanner, long-range radar and camera in the front. Then there are 21 other sensors, including four mid-range radars at the corners, four surround cameras, 12 ultrasound sensors, and an infrared camera. All of these sensors are actively looking for lane markings, other vehicles and objects.
But there is also an intelligent powertrain management system. This system makes use of information including sensor input as well as navigational route data. The powertrain management system is then able to calculate such things as whether to put the car into coasting mode or to use regenerative braking to recover energy (up to 12 kW). In addition to which, the system can use the BAS system to slow the A8 should a vehicle be traveling in front of the car. That leads to additional energy gain, which Audi calculates is on the order of 0.2 U.S. gallons per 62.1 miles (or 0.7 liters per 100 km). Perhaps not much, but every drop helps.
While the new A8 is the first of many electrified vehicles that will be coming from Audi during the next several months, mild hybrids as well as fully electric vehicles (the company anticipates that by 2025, one in three Audis will be an EV), there is one Audi EV that has absolutely nothing mild about it: the Audi e-tron FE04. It is the first fully electric race car for the Formula E series to come from Audi, and it is the first to come from a German OEM. Audi is working with Tier One supplier Schaeffler Group USA Inc. (schaeffler.com; which has powertrain expertise not only for internal combustion engines, but for hybrids and EVs, as well, with products including hybrid modules, electrical axle drives, range extender transmissions, hydrostatic clutch actuators, and electrical wheel hub drives).
When it comes to racing and advancing technology, Audi has a powerful pedigree. Although “diesel” is not generally thought out in a particularly positive light nowadays, when Audi went racing at the 24 Hours at Le Mans with the diesel-powered R10 TDI, it claimed the first victory for a diesel in 2006. Then it won again in 2007 and 2008. Then the R10 TDI was replaced by the R15 TDI, again, diesel powered, and it won at Le Mans in 2010, 2011, 2012, 2013 and 2014.
It also developed a hybrid race car for Le Mans, the R18 e-tron quattro. And it took the top place at the podium in its class three times running: 2012, 2013 and 2014.
So arguably its participation in Formula E is being done so with the same underlying concept of technology advances. (E.g., during its run of the diesel powertrain at Le Mans, it managed to improve overall fuel efficiency by 46 percent.)
The e-tron FE04, the Audi Sport ABT Schaeffler vehicle, has a powertrain—motor and transmission combination—that was jointly developed by Audi and Schaeffler. A key area of focus was on the motor-generator unit, where they sought efficiency that would help propel the car more effectively when it comes out of corners.
The series requires that the maximum output of the motor for qualifying is 200 kW (272 hp) and 180 kW (245 hp) during a race. To make Formula E more engaging for the fans, there is what is called “FanBoost.”
A given Formula E race lasts about 50 minutes. Given that the cars accelerate from 0 to 100 km/h in about 3.5 seconds, the 34 kWh lithium-ion battery pack developed for the series by Williams Advanced Engineering has developed and that is identical for all cars, and of which 28 kWh can be used can’t make the entire run. So about halfway through the race each driver has a mandatory pit stop—and during this stop, the driver gets into a second car to continue the race.
Which brings us back to the FanBoost. Fans vote on Twitter, through the Formula E website, and through a Formula E app before the race and six minutes into the contest. The three drivers who get the most votes get the FanBoost, which provides them with an additional 100 kJ of energy once they’re in a power window of 180 to 200 kW. They push a button on the console and the additional electricity is released.
The just-started Formula E series is its fourth. Next year, there will be a whole new vehicle design for the series (which means, of course, that the e-tron FE04’s debut year is going to be its only year) that will include a battery with twice the capacity as the current one, so there will be no obligatory car change during the middle of the race.
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