The 48V Ethernet Powered Automotive Future
2020-05-01 | 7 min read
Cars are becoming more reliable and long-lived, which is important because they are also becoming more complex. Some of the complexity has come from safety requirements – airbags being one example. Introduced in the early 70's in the Olds Toronado, one could still get driver side only airbags into the 80's. Now cars might have ten or more airbags in addition to seat belt airbag systems.
A big challenge that automobile manufacturers are facing is fuel economy. Whether or not you view currently scheduled EPA fleet-wide fuel economy standards of 52.6 mpg by 2025 (7 years to go and we are about half way there) as realistic or not, one thing that is clear is that in a world of intense competition and regulatory pressure auto makers need to fully leverage every advantage they can find.
Interestingly, a couple of recent advances, while fundamentally electrical/electronic in nature, will help internal combustion vehicles achieve higher efficiency.
48 Volts – More is More
In the past, automobile electrical systems were 6V. Back in the day when feebly glowing headlights, turn signals, a small radio and a modest starter hooked up to a relatively low compression engine were the only things drawing current, 6V was barely enough. Around 1953 with the introduction of higher compression engines in the US, it became clear after a summer or two 6V starters struggling to turn over hot engines that something needed to be done. Enter 12V electricals and all was well for decades.
Until it wasn't. In the quest for ever more efficient running, makers are increasingly turning to electrical rather than mechanical or hydraulic power. Steering, for example and much to the woe of many enthusiast who lament the lack of feel in many systems, is now largely electrical. Accessories such as radiator fans and water pumps, which used to be mechanically driven, are now increasingly electrical.
Meanwhile another pair of trends, automatic engine stop and small displacement turbos are further aiding the 48V cause. Automatic engine stop also implies automatic engine start – which for a good user experience requires some pretty robust gear, gear which is easier to build in 48V form. Just starting the motor is only the start of the battle – remember, small displacement turbos are very popular, but tend to be pretty gutless until the turbo spools up, which takes time, time which you don't have when the light turns green. One workaround? Electrical augmentation of the turbo to spool up the turbo impeller at the same time the engine starts – making for far better response off the line when coming off an auto-stop. Of course spinning up turbos works far better with 48V than 12V.
Another factor in favor of 48V electrical in cars is wiring. When running current at higher voltage, the same wiring can carry more current capable of doing more work or less wire can carry the same current allowing for savings in both cost of materials as well as overall weight for the vehicle.
On the topic of wiring…
Which brings us to another interesting area – automotive Ethernet. One of the challenges of existing solutions, be they CAN (Controller Area Network), FlexRay, LVDS (low voltage differential signaling) or MOST (Media Oriented Systems Transport) is that the relatively complex and heavy wiring harnesses the require. With these solutions, the wiring harness ends up being the third most expensive component of the car – they are usually made one at a time by hand and can consume up to 50% of the labor that goes into building the car. These complex wiring harnesses are pretty heavy – many weighing in excess of 200 lbs.
On top of being complex and heavy, bandwidth may in some cases be limited. One way around all these concerns is with automotive Ethernet. With the rise of complex hybrid systems, wireless (both WAN and Wi-Fi), infotainment and drive by wire systems Ethernet provides manufacturers with a proven method of hooking up all the systems and subsystems that need connectivity while ensuring everything gets that latency and bandwidth required. Best of all, the complex and heavy wiring harnesses mentioned earlier can now be significantly lighter and simpler.
In the end, the automotive industry is a tough and fiercely competitive market with significant barriers to entry. It also requires constant research and development in order to maintain compliance with the latest safety, emissions and fuel economy requirements while also keeping up with consumer demands. A couple ways that manufacturers can help achieve these often comflicting goes include starting to roll out 48V systems and if they have not done so already augmenting these efforts with automotive Ethernet.
Learn more about automotive Ethernet testing and how Keysight can help.