奥迪旗下的第一款纯电动车型e-tron即将投产，其性能亦是不负众望的一流卓越。

By Bill Visnic

今年9月17号，大众奥迪推出了旗下第一款纯电动车型e-tron，而就在一周之前，奥迪的主要竞争对手奔驰发布了EQC纯电动车。另一家车企—捷豹更是捷足先登，早在几个月之前就推出了i-Pace纯电动车。如此紧锣密鼓的产品亮相，似乎是在宣示纯电动车时代已然到来。除了主打纯电动以外，奥迪、奔驰、捷豹推出的新车还体现了当下纯电动车热潮的另一特征——它们都是跨界车。

三年前，奥迪发布了e-tron的概念车型，那也是e-tron的首次亮相。时隔三年后，在旧金山华丽的全球发布会上，奥迪终于揭开了e-tron量产车型的神秘面纱。目前，e-tron已经在位于比利时布鲁塞尔的奥迪工厂投产，奥迪计划在年底之前在欧洲交付。而美国的开售时间定在了2019年第二季度，这也是奥迪反复斟酌后做的决定。价格方面，e-tron不算亲民。科技感十足的Prestige标配版起价74,800美元。奥迪还将限量发布999辆First Edition版，定价也是三款车型中最高的— —86,700美元，

车型优势

尽管特斯拉是高端电动汽车的标杆，奥迪e-tron的一大优势在于它的车型— —跨界车，这点和奔驰EQC和捷豹i-Pace一样。相较之下，特斯拉只倾心于轿车。奥迪美国产品经理Matt Mostafaei表示，美国消费者非常看重车型，“e-tron的第一大卖点是中型SUV，第二大卖点才是纯电动。”

五座的e-tron诞生于大众 MLB前置横向发动机动力总成通用化平台，大小适中，介于奥迪的中型Q5和全尺寸3排Q8跨界车之间。e-tron长193 英寸（4902毫米），宽86.3英寸（2192毫米），轴距为115.1英寸（2924毫米）。和Q5相比，轴距加长了4英寸（102毫米），总体车身则加长了10英寸（253毫米）。

在旧金山亮相的e-tron看上去除了尺寸大以外，重量也不轻。尽管奥迪的宣传材料中并没有揭示欧版和美版的整备质量，但根据一位奥迪的内部人士透露，e-tron重达2490千克（5490磅）。不过，考虑到车上搭载了净重为700千克（1543磅）的电池包，这个重量也就不足为奇了。

电池大，充电快

e-tron搭载的95千瓦时的锂电池包由432块袋装电池组成，共有36个模块。电池由韩国LG化学公司负责生产。电池盒由奥迪内部负责设计制造，以坚固的铝材为主，能有效保护电池抵抗冲击。此外，为改善热管理，电池包还设有特殊设计的冷却液环路。

e-tron系列项目负责人Jens van Eikels告诉《汽车工程》杂志， e-tron的四条冷却液环路是e-tron中最复杂的系统之一。除了密切管理电池包的温度以外，电池包的冷却液还会流向前后车桥的驱动电机，也会流入调节座舱温度的热泵。VanEikels表示，e-tron的热泵比传统汽车的效率要高15%。和驱动电机相连的冷却液特殊管路可以非常有效地降低电机和整合式单速行星变速箱的温度，没有必要再冷却变速箱油，因此不用安装油泵。

e-tron还有一个别出心裁的冷却设计：冷却液管道采用网格状结构，不会和电池模块发生直接接触，电池模块上涂覆的特殊凝胶会将热量转移到冷却液管道中。

奥迪之所以如此重视电池热管理，也是因为这会影响到e-tron的充电速度和电池容量。美版e-tron搭载了一个9.6千瓦的充电器，奥迪声称这是市面上所有纯电动车型中功率最高的充电器。如果使用240伏（即40安倍）的家用电源，容量为95千瓦时的电池包在约8.5小时内即可充满80%。

如果使用标准SAE-J1772规格的组合式充电系统（CCS），e-tron的最高充电速率可达150千瓦。如此一来，电池包可在不到30分钟内充满80%。如果是在公共充电站充电，按照50千瓦的速率，充电时间大概为80分钟。

不过，如果使用目前标准的120伏家庭用电，充满80%需要大约90小时。想必多e-tron车主定会更倾心于240伏电路。为此，奥迪也和亚马逊签订了一项协议，未来将由亚马逊家庭服务公司为车主安装240伏电路。但是，在奥迪看来，最佳充电功率应该是350千瓦。大众集团旗下的子公司ElectrifyAmerica 已经开始着手安装350千瓦的充电桩，如果使用这种充电桩，e-tron的充电时间将不到12分钟。

然而，e-tron最重要的电池性能参数还有待观察。奥迪声称目前还不能确定e-tron的续航里程。截止到全球首发之前，最可靠的数字是e-tron的全球轻型车测试规程（WLTP）的测试结果：400公里（249英里）。这个数字应该非常接近美国监管部门的测试结果。

新的转折：电动四驱

据e-tron动力总成工程师Joachim Dorr博士介绍，e-tron的标配是前后车桥上驱动四轮的交流异步牵引电机，其精准度更是达到了前所未有的水平。Dorr博士说，e-tron的电动四驱系统“打开了奥迪四驱技术的新篇章”。

Dorr博士说，“在我看来，e-tron拥有奥迪最出色的四驱技术。”

尽管奥迪声称美版e-tron的配置参数尚未最终确定，根据发布会我们可以预测，后桥异步电机负责在普通工况下输出主要的牵引扭矩，功率大概为140千瓦（188马力）。前桥电机的功率为125千瓦（168马力）。两台电机加起来的输出扭矩最高可达413磅·英尺（561 牛·米）。

奥迪还透露，sport模式下，踩住油门可以激活特殊增压技术，电机的功率最高可达300千瓦（402马力），最高输出扭矩为490磅·英寸（664牛·米），百公里加速仅为5.5秒，这也是e-tron系列的最快速度。有评论人士指出，e-tron的加速性能之所以不是非常惊艳，很可能还是因为e-tron的重量。不过，e-tron瞄准的是高端SUV中端市场，极致的性能并不是它的主要目标。话虽如此，奥迪还是可能在以后推出性能不同的e-tron车型。

e-tron项目负责人van Eikels表示，电动四驱的调校速度非常快，可以在较为轻松的工况下，将后桥的扭矩矢量的转化为制动力，分配给四轮，传递扭矩矢量效应。

驱动电机将在位于匈牙利杰尔的历史悠久的奥迪内燃机工厂投产。转子将不使用稀土元素，转子和定子都是由奥迪内部设计制造。其它的零部件将由外部供应商提供。具体是哪些供应商，奥迪还没有透露。奥迪计划在年底之前，通过采用新型模块化生产系统实现400台的电机日产量。届时每个电机将不使用流水线工艺，而是由自动小车运送到各个组装工位。

e-tron的驱动系统当然也包含了制动能量回收技术，回收比例可由驾驶员自行选择。奥迪美国总裁Scott Keogh声称，这是迄今为止效率最高的电池能量回收系统，可以将e-tron的续航里程提高30% 。

浪潮的前奏

Keogh表示，e-tron是奥迪进军电动化的序曲。到2025年前，奥迪计划在全球推出12款纯电动车型，电动车将占到销量的三分之一。

继今年9月之后，奥迪将在明年推出e-tron的Sportback版，然后再在11月的洛杉矶车展上发布一款主打运动性能的GT轿跑概念车型。

The first-ever electric vehicle from Audi, the e-tron, is production-ready. As expected, it's impressively engineered.
By Bill Visnic

It seems safe to say the global shift to battery-electric vehicles is now in full swing, with the Volkswagen Group's Audi brand unveiling on September 17 its first electric vehicle (EV), the e-tron, barely a week after chief rival Mercedes-Benz revealed its EQC and mere months after Jaguar launched its i-Pace. An additional sign of the times: all three new luxury EVs are crossovers.

In a glitzy global reveal event in San Francisco, Audi finally pulled the sheet off the production version of the e-tron, some three years after it was first shown as a concept. Production already is underway in Brussels, Belgium, with Audi intent on delivering the first customer vehicle in Europe by the end of this year. The company is cautiously pegging the start of U.S. sales for the second quarter of 2019 and the e-tron will not be inexpensive, with the heavily-equipped Prestige “base model starting at $74,800 and moving to $86,700 for First Edition (limited to a run of 999 units), which tops the three-trim e-tron lineup.

Bodystyle jackpot

Although Tesla is the obvious target for any new luxury-brand EV, Audi's advantage (as well as for the Mercedes-Benz EQC and Jaguar i-Pace) is that the e-tron is a crossover, while Tesla remains oriented towards sedan body styles. It's a critical point for U.S. consumers, said Audi of America's Matt Mostafaei: “The e-tron is a midsize SUV first and an electric car second.”

Derived from the VW Group's essentially powertrain-agnostic MLB (front longitudinal-engine) platform, the 5-seat e-tron is sized conveniently between Audi's midsize Q5 and the fullsize, 3-row Q8 crossovers: the e-tron is 193 in (4902 mm) long and 86.3 in (2192 mm) wide, with a wheelbase of 115.1 in (2924 mm), making it 4 in (102 mm) longer in wheelbase and nearly 10 in (254 mm) longer in overall length than the Q5.

Seen at its San Francisco revealing, the e-tron has an ample footprint— and weight to match. Although the company's press material did not reveal a curb weight for the crossover in either European or U.S. configuration, one Audi source pegged the e-tron at a stupendous 2490 kg (5490 lb)—not an unimaginable figure considering the battery pack alone weighs a claimed 700 kg (1543 lb).

Big battery, big charging ability

The 95 kWh lithium-ion battery pack is comprised of 432 pouch-type cells grouped in 36 modules; the cells are made by Korea's LG Chem. Audi designed and builds the clever battery enclosure, incorporating exceptional protection from crash intrusion via a robust, largely-aluminum structure that also was specially conceived to facilitate thermal management with incorporated cooling circuits throughout the battery pack.

The e-tron's four coolant circuits are “one of the most complex systems of the car,” Jens van Eikels project leader of e-tron car line, told Automotive Engineering. In addition to closely managing the temperature of the battery pack, coolant also flows to a drive motor at each axle, as well as to the heat pump that provides cabin climate control. The heat pump is some 15% more efficient than a conventional HVAC system, van Eikels said, while the special coolant “spears” designed into the drive motors are so effective in drawing heat from the motors and integrated single-speed planetary transmission that there is no need to cool the transmission oil, also eliminating the need for an oil pump.

Another cooling innovation: the coolant lines do not directly contact the battery modules, instead running in a grid-like pattern in the structure itself; heat transfer is accomplished via a special gel that surrounds the modules.

Audi makes much of the built-in charging capability of the e-tron and the thermal-management performance also plays a role in the speed and capacity at which charging can take place. Onboard for U.S. models is a 9.6-kW charger that Audi said is the highest capacity of any currently-available EV. It means a household 240-volt/40-amp circuit can provide an 80% recharge of the 95-kWh battery pack in about 8.5 hours.

The e-tron can be charged at up to 150kW, however, through its standard SAE J1772-spec Combined Charging System (CCS) connector. At the 150-kW rate,

the battery pack can be recharged from 80% depletion in less than 30 m. At the 50-kW rate currently available at some public charging stations, an 80% recharge will require about 80 m.

Those without the requisite household 240V circuit surely will want to install one, however, as charging on standard 120V current would require some 90 hours! To that end, Audi has entered an agreement with Amazon Home Services to broker installation of a 240V circuit. Audi sees the charging end game, however, at a 350-kW rate—now starting to be installed by the VW Group's Electrify America subsidiary—that would recharge the e-tron in less than 12 m.

But perhaps the most-important aspect of battery performance remains unaddressed for now: Audi said it does not have official driving-range figures for the e-tron. The best-available figure at the time of the e-tron's global unveiling was the 400-km (249-mile) rating from Europe's new Worldwide Light-vehicle Test Procedure (WLTP), which may be reasonably close to what U.S. regulators will derive.

New twist: Electric Quattro

Standard for every e-tron is an AC asynchronous traction motor at each axle that imparts all-wheel-drive capability with a new level of precision, said Dr. Joachim Dorr, a powertrain engineer for the e-tron, who called the electric-drive quattro system “the next chapter in Audi all-wheel-drive technology.

“In my personal opinion,” he added, “the e-tron has the best quattro drive we've ever made.”

Although Audi said U.S.-specification output figures are yet to be finalized, information at the crossover's press reveal indicated the asynchronous motor at the rear axle (which under normal driving is designed to deliver the majority of tractive torque) is rated at approximately 140 kW (188 hp). The front-axle motor generates approximately 125 kW (168 hp) and the combined torque output is a maximum of 413 lb.ft (561 N. m).

A special “boost” mode—engaged by pinning the accelerator pedal whenever the drive control is in “sport” mode—will command a maximum of about 300 kW (402 hp) and 490 lb.ft (664 N.m). Using this function delivers the e-tron's best 0-60 mph (0-97 km/h) acceleration time of 5.5 s, Audi said. Early critics noted the acceleration performance is not particularly impressive and likely is related to the e-tron's not-inconsiderable weight. The e-tron also seems targeted at the middle of the luxury utility-vehicle market, where extreme performance is not a high priority; Audi might be expected to in the future offer performance variants of the e-tron.

Project leader van Eikels said the all-electronic quattro “tuning” is particularly fast-acting and also allows for a certain degree of torque vectoring at the rear axle and accompanies braking at individual wheels to impart a torque-vectoring effect in less-strenuous driving situations.

The drive motors are built by Audi at its longstanding IC engine plant in Gyor, Hungary. The rotors use no rare-earth elements and the stators are Audi-designed and built, with other motor components coming from external suppliers Audi did not detail. By the end of the year, the company intends to make about 400 motors daily under a new modular production system that sees each motor travel to assembly stations on automated carts rather than an installed conveyor line.

The e-tron's drive system of course incorporates driver-selectable degrees of regenerative braking effect. Audi of America president Scott Keogh called the system “the most-efficient battery recuperation to date,” adding that it can contribute up to 30% of the e-tron's total driving range.

Start of the wave

The e-tron is the beginning of Audi's push to electrification, Keogh said. By 2025, Audi intends to have 12 EVs in its global product portfolio and sees one-third of sales comprised of electrified models.

Following the e-tron is a “Sportback” version next year, while a sport-oriented GT concept coupe is slated to be revealed at the Los Angeles auto show in November.

Author: Bill Visnic
Source: SAE Automotive Engineering Magazine