Whether it’s autonomous, semi-autonomous, or electric, the modern vehicle is consuming more power — its evolution toward a data center on wheels means there are many opportunities to make it more energy efficient without compromising smarts.
The smarter the vehicle, the greater the need for energy efficiency. An ongoing challenge for self-driving vehicles is the immense amount of power needed for autonomy — onboard sensors draw a significant amount of power while in-vehicle computing is constantly making calculations to support instant driving decisions.
The many gigabytes of data per second being generated put demands on power, so, like a server or smartphone, the modern vehicle needs to be smart about energy consumption because, unlike a server or smartphone, automotive power usage affects fuel economy and EV range.
Every Automotive Function Competes for Power
The typical automobile has become more power hungry over the decades. Gone are the days of a simple radio or perhaps a tape deck for onboard entertainment, and power windows and locks are now standard. Even a basic advanced driver assistance system (ADAS) with a rear-view camera is now standard — even required — which means the dashboard of even a modest new car looks more like a console in NASA mission control.
Mix in GPS, satellite radio, and onboard media storage, and the power requirements for the average vehicle tick up quickly; that doesn’t even include lower levels of autonomy, let alone all the electronics content and computing capabilities that are required for a self-driving vehicle. The automotive architecture is chock full of embedded electronic systems necessary for supporting the engine, chassis, safety features, and passenger entertainment.
Engine electronics in the form of engine control units (ECU) are distributed through the modern automobile to control functions such as emissions, ignition, cooling, throttling, and fuel injection, among others. These ECUs must communicate with chassis electronics subsystems that encompass traction control, electronic braking distribution and anti-lock braking, and parking assistance. Passive safety systems also require electronic components for airbag control and deployment, emergency braking, and control of hill descent in the event of a collision or other incident on the road.
Less mission critical but standard in vehicles are passenger comfort features such as automatic climate control, electronic seat adjustment, automatic environmental controls, and automatic wipers, as well as any entertainment and navigation systems — they all fall under the “infotainment” systems umbrella.
All this electronics content is evolving and proliferating as vehicles become more intelligent, while systems such as ADAS become even more electronics dependent by incorporating heads-up displays and in-cabin gesture recognition. More electronics and capabilities don’t have to mean more power — just as smartphones have added features while becoming more energy efficient, so can cars.
Automotive Data Must Be Moved and Stored Efficiently
Opportunities to reduce power consumption in the car can be found in many electronic components that are required to make the modern vehicle smarter and autonomous — memory and storage devices, sensors, and connectivity, both wired and wireless.
Although full Level 5 autonomy is taking longer to achieve on a widespread basis, Level 2 and Level 3 autonomy in the form of driver-monitoring systems, adaptive cruise control, lane keeping, and automatic braking mean more data, which means more memory and data storage. This is where power-efficient memory plays a role in reducing overall energy use in the vehicle, even as systems become increasingly complex and more computing is done in the car.
Functions that require higher-capacity memory and rapid processing can employ LPDDR4X/5X to balance performance and power as we move closer to realizing Level 4 and Level 5 autonomous vehicles that run artificial intelligence-enabled applications that must also meet high levels of functional safety. NOR flash is ideal for storing small amounts of data through devices in the vehicle and supporting “instant on” requirements so power isn’t consumed until the key is turned in the ignition.
For high-capacity storage, NAND flash-based devices that have been optimized in other use cases such as those using eMMC or Universal Flash Storage (UFS) can store infotainment data. SSDs can even be deployed to consolidate an information storage device with built-in intelligence that prioritizes availability and reliability of mission-critical data. Their reliability is due in part to a lack of moving parts, which also contributes to a better power-usage profile.
Aside from memory and storage, connectivity and sensors are ubiquitous in the modern vehicle — not only is it a data center on wheels, but it’s also its own Internet of Things (IoT) ecosystem with onboard devices that must talk to each other as well as communicate to the environment around — especially if the vehicle is fully autonomous.
Even small sensors have power requirements, and when there’s lots of them, that energy consumption can add up — the modern automobile is chock full of sensors to monitor vehicle conditions, detect obstacles while driving and parking, and even keep tabs on the health of the driver — a low-power infrared temperature sensor requires roughly 15mW of power, which doesn’t sound like much. However, a key challenge with automotive design is that energy is inevitably lost as heat. Some of this lost energy can be recouped by harvesting this waste heat with thermoelectric generators (TEG), which act as power sources, especially in embedded systems. Because they are solid-state, they require almost no maintenance and improve the overall system performance by helping to power sensors.
Automotive Ethernet also plays a critical role in energy efficiency while helping to move all the data around the vehicle to where it’s needed. Power over Ethernet eliminates the need for additional power sources as well as reduces the wiring in the vehicle and allows data transfer between vehicular devices at usual speed. Energy-efficient Ethernet, meanwhile, reduces power consumption by turning off network segments when the engine is off and using energy-efficient Ethernet when the engine is on.
If You Can’t Dissipate the Heat, Get Out of the Car
Another path to better automotive power consumption is via wide bandgap semiconductors (WBG) that use materials such as silicon carbide (SiC) and gallium nitride (GaN), both of which have a relatively large energy bandgap. Compared to silicon, SiC and GaN can deliver significant performance improvements and better operating efficiency and reliability in harsh environments, including automotive.
Resistor technology also has a role to play in automotive energy efficiency; wide terminal resistors, for example, have an excellent power-to-size ratio as they dissipate much of their heat via the wide terminals on the device — while the “reduced hotspot design” of pulse tolerant resistors means they can dissipate more power in the steady state.
There Are Multiple Paths for Automotive Power Management
Energy efficiency in the modern vehicle is now table stakes — power consumption must always be a key factor when choosing the compute, memory, storage, or connectivity required to move data in the automotive environment. The smarter the vehicle, the more energy efficiency must be prioritized and managed through reduced power consumption, energy harvesting, and better thermal management.
