未來(lái)，高度自動(dòng)駕駛汽車（SAE 4級(jí)）和全自動(dòng)駕駛汽車（SAE 5級(jí)）將采用何種推進(jìn)系統(tǒng)？考慮到自動(dòng)駕駛汽車需要消耗大量電力進(jìn)行數(shù)據(jù)處理，那么為了抵消這部分“自動(dòng)駕駛開(kāi)銷”，未來(lái)的自動(dòng)駕駛汽車需要比當(dāng)今車輛更高效的推進(jìn)系統(tǒng)。根據(jù)博格華納（BorgWarner）副總裁、CTO Chris Thomas的說(shuō)法，解決這個(gè)問(wèn)題的成本不會(huì)低。
4月3日，在底特律舉行的SAE 2017年高效內(nèi)燃發(fā)動(dòng)機(jī)研討會(huì)（SAE 2017 High-Efficiency IC Engines Symposium）上，Thomas告訴在場(chǎng)觀眾，光是處理越來(lái)越多的傳入數(shù)據(jù)和車載數(shù)據(jù)（來(lái)自車載傳感器陣列、其他汽車、道路設(shè)施及云端），自動(dòng)駕駛汽車就需要消耗1.5 kW至2.75 kW的功率。這，就是自動(dòng)駕駛汽車“不為人知的小秘密”。
舉個(gè)例子，拿一輛典型的B級(jí)車來(lái)說(shuō)，大約每消耗39W電力就相當(dāng)于排放1g CO2。
Thomas指出，來(lái)自英特爾（Intel）和英偉達(dá)（Nvidia）的新型專用處理器可逐步減少最高90%的電力消耗。如果電力消耗水平真的可以下降90%，那么一輛常見(jiàn)車輛的數(shù)據(jù)處理功率需求應(yīng)該在200 - 350 W左右。
“根據(jù)我們的計(jì)算，在最好的情況下，我們也僅能將每輛自動(dòng)駕駛汽車的等效CO2排放水平降低至10g到20g克。”Thomas解釋說(shuō)，這仍然將為車輛推進(jìn)系統(tǒng)增加3到6%的電力負(fù)擔(dān)，嚴(yán)重影響車輛的能效表現(xiàn)。
“這意味著，未來(lái)自動(dòng)駕駛汽車的推進(jìn)系統(tǒng)必須比今天的好很多才行。”Thomas指出，“我們需要將BTE提升至50 - 51%。如果內(nèi)燃系統(tǒng)的能效不能顯著提升，那么自動(dòng)駕駛汽車將很難成為現(xiàn)實(shí)。”
盡管Thomas認(rèn)為自動(dòng)駕駛汽車并不會(huì)具體區(qū)分推進(jìn)系統(tǒng)，但在未來(lái)20年中，從對(duì)冗余制動(dòng)系統(tǒng)（及冗余電池）的需求考慮，插電式混合動(dòng)力車可能是最實(shí)際的選擇。他大膽猜測(cè)，純電動(dòng)汽車可能也不會(huì)在自動(dòng)駕駛領(lǐng)域扮演重要角色。
“自動(dòng)駕駛汽車的正常運(yùn)行時(shí)間正在不斷增加，每天的累計(jì)行駛時(shí)間可能超過(guò)10小時(shí)，必須進(jìn)行大量充電。”他解釋說(shuō)，“在紐約城，出租車每天的行駛時(shí)間一般在18個(gè)小時(shí)，這同時(shí)意味著夏季每日要開(kāi)18個(gè)小時(shí)的空調(diào)，冬季要開(kāi)18個(gè)小時(shí)的暖氣，而只要開(kāi)空調(diào)或是暖氣，純電動(dòng)車的續(xù)航里程將立刻減少30到50%。因此，我覺(jué)得電動(dòng)汽車可能不會(huì)出現(xiàn)在商用領(lǐng)域以外的自動(dòng)駕駛汽車市場(chǎng)中，至少在短期內(nèi)不會(huì)。”
如果城市中心地區(qū)能夠提供電池充電/更換站點(diǎn)等設(shè)施（類似于目前的加油站），這種情況可能會(huì)發(fā)生變化。Thomas指出，但大量電動(dòng)車同時(shí)進(jìn)行直流快充將導(dǎo)致電網(wǎng)壓力激增，這也是一個(gè)很實(shí)際的問(wèn)題。
What type of propulsion system will power the highly automated (SAE Level 4) and fully autonomous (SAE Level 5) vehicles of the future? Such systems will need to be more efficient than those used in today’s human-driven vehicles, to offset the “autonomous overhead”—the significant amount of electrical power required for data processing alone. And they won’t be the lowest-cost solution, according to Chris Thomas, BorgWarner’s vice president and CTO.
The 1.5 kW to 2.75 kW needed just to process the increasing deluge of incoming and in-vehicle data—generated from on-board sensor arrays, from other vehicles, the infrastructure and the cloud—is “the dirty little secret” of autonomous vehicle engineering, Thomas told the audience at SAE’s 2017 High-Efficiency Engines Symposium in Detroit on April 3.
For a typical B-segment vehicle, for example, about 39 W of electricity consumed is equivalent to about one gram of CO2 emitted.
Thomas noted that new dedicated processors from Intel and Nvidia will inevitably help reduce electrical consumption by up to 90%. That means that with a 90% reduction in energy consumption, a typical vehicle’s processing power demand may be 200 to 350 W.
“By our calculations, the best case-scenario is that we’ll end up with about a 10-g to 20-g CO2 penalty per autonomous vehicle,” Thomas explained, translating into a 3-6% burden for the propulsion system and a significant “hit” to vehicle efficiency.
“That means the propulsion system has to be that much better than today’s,” he noted. “We need to get to a 50-51% BTE to make that happen. That’s not plausible without hybridization coupled with significantly more efficient combustion engines.”
While Thomas considers autonomous vehicles to be “propulsion agnostic,” the need for redundant braking systems (and redundant batteries) makes plug-in hybrids the practical prime-mover in this area for perhaps the next 20 years. He reckons battery-electric vehicles won’t play a major role in autonomous use during that period.
“The increased uptime of autonomous vehicles could mean more than 10 hours per day of operation, in which a significant amount of charging would be required,” he argues. “A typical New York cab runs 18 hours a day which means it needs 18 hours of air conditioning in the summer and 18 hours of heat in winter. In a BEV you lose 30-50% of the range when you turn the A/C or heat on. So I don’t think we’ll see BEVs used for autonomy outside of some commercial vehicles, at least in the short term.”
If battery exchanges/swapping at centralized locations were made accessible, that scenario could change if an infrastructure (similar to gas stations) were implemented, he said. DC fast charging of entire fleets of vehicles would create too great a spike in the electrical grid to be practical, Thomas noted.
Author: Lindsay Brooke
Source: SAE Automotive Engineering Magazine
在2017年高效內(nèi)燃發(fā)動(dòng)機(jī)研討會(huì)上，博格華納首席技術(shù)官Chris Thomas揭露了自動(dòng)駕駛汽車“不為人知的小秘密”。
