Why Efficiency is Critical in Electric Vehicles

Article By : Jamie Broome, Imagination Technologies

How can automakers deliver the features of the car of the future without impacting the range of that car?

This month’s In Focus looks at the latest developments, challenges, opportunities, and strategies in the electric vehicle (EV) space.


Electric vehicle (EV) ownership is exploding in popularity. By 2030, an estimated 10 million vehicles on the road will be fully electric with as many as 36 million by 2040. With government targets for carbon emissions and consumers becoming more aware of the benefits of EVs, both in terms of cost and environmental impact, the automotive industry is at a tipping point. This change also comes at a time where advanced driver-assistance systems (ADAS) and autonomous driving are moving ever closer.

With Level 3 and 4 autonomous driving becoming more and more available, allowing drivers to take their eyes off the road and their mind off the task of driving. There is an ever-growing need for a wealth of sensors being added to vehicles to replace the driver’s eyes on the road. Increased numbers of cameras, exterior LIDAR and even interior sensors to monitor occupant safety and attention are great for the future of driving but are very challenging for one thing: power consumption.

With every watt of power used by a sensor affecting the range of the vehicle, how can automakers deliver the features of the car of the future without impacting the range of that car?

Designing with EVs in mind

One simple way to do this is with improving efficiencies in the systems themselves. By developing lower powered sensors that can still collect data we can make an immediate saving in power, but all the data collected needs to go somewhere and with more data comes an increasing burden on the silicon to process it. High level concept cars for autonomous driving and cutting edge ADAS systems rely on a desktop grade GPU solution that is water cooled to be able to brute force their way through these dense and complicated calculations. But, when you are limited in your battery capacity, a 350W GPU is not going to cut it.

One of the best ways around the issue is to design from the ground up with the car as a platform in mind. Rather than trying to make something else work, it is much better to have higher density silicon to allow for much more efficient computation whilst also reducing the silicon area in the vehicle. With a bespoke design, comes the ability to get functional safety built in from the ground up. As an example, the recent XS-series of Imagination GPUs for automotive feature ISO 26262 compliance. What this means is that a single GPU can fault check itself internally instantly halving the automakers silicon requirements by 50% vs. a lockstep solution.

From macro to micro, making small gains scale up

In our main ADAS workhorse GPUs we now have a custom designed, high density, functionally safe chip, but how else can we bring the power requirement down to give drivers maximum miles on the road without having to turn everything off to limp home?

In any modern vehicle there are already hundreds of electronic control units (ECUs) distributed throughout the car, these can control and monitor high-end ADAS functionality or even just the electric wing mirrors of a vehicle. Each of these microcontrollers needs its own core to control its actions multiplying the power budget throughout the car, one or two is no measurable impact, but at scale, it’s a lot of wattage. Bringing the number of ECU’s in a vehicle down has always been a matter of functional safety once again, each core needs to manage a single application or function to ensure no cross over of information and a functionally safe environment, but once again IP vendors are looking at how to challenge this norm in a safety focused way.

One way to bring this number down is to connect multiple functions from different ECU to a single multi-core ECU, by bringing functions together, either by location and application we can reduce the need for independent ECU’s and the power that brings. Hardware virtualization is the other half of this coin. What it allows a GPU to do is run several workloads, for example, dials and clusters, reverse cameras, and the infotainment center console on a single piece of silicon. By isolating each of these workloads to a single core on the GPU, multiple operating systems and functions can run simultaneously and independently. Coupled with functionally safe standards like ISO 26262 to self-check for faults in each core, its easy to see how the number of ECUs can be drastically reduced.

Keeping things moving forward

EVs aren’t going anywhere, and neither is the industries push for a safer more autonomous driving future. From ADAS to door locks, every watt matters , and the glue that will bind EVs and autonomy they go forward is the IP vendors and silicon manufacturers who continue to develop elegant custom, low power solutions across the range of features in a vehicle.


About the Author

Jamie Broome is the Senior Director of Automotive Product Management at Imagination Technologies.


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