Using ICs To Shrink Auto’s Carbon Footprint

A large portion of the burden for reducing greenhouse gases is being handed off to makers of automotive chips and systems, which are being tasked to make vehicles drive further using less energy and with zero emissions.

The effort is critical in battling climate change. According to the U.S. Environmental Protection Agency, the transportation sector represented 28.2% of 2018 greenhouse gas emissions, which is the single largest component. These emissions are primarily from burning fossil fuel for cars, trucks, ships, trains, and planes, which today is more than 90% based on oil. And those numbers don’t factor in the manufacturing of the vehicles themselves.

“If we are serious about decarbonization, vehicle electrification is critical,” said Puneet Sinha, director in the New Mobility Mechanical Analysis Division at Mentor, a Siemens Business. “To get a picture of the carbon footprint of vehicles, the baseline is the internal combustion engine vehicle. If an internal combustion engine vehicle is driven between 120,000 and 150,000 miles, its lifetime carbon footprint is approximately 260 grams per kilometer, out of which 160 to 165 grams per kilometer comes from the tailpipe. Approximately 50 grams per kilometer is the fuel cycle, with the manufacturing of the vehicles about 45 grams per kilometer.”

Hybrid vehicles are more efficient. Tailpipe emissions are about 60% to 70% lower than an internal combustion engine due to improved fuel efficiency. For pure electric vehicles, the tailpipe emissions drop to zero, but there are still emissions from manufacturing and the generation of electricity. Even if the electricity is from a clean energy source, there is a carbon footprint for manufacturing the generation equipment. That electricity also needs to be stored in a battery, and manufacturing of battery cells and packs is energy-intensive.

“If you look at the landscape of electric vehicles, while the tailpipe emission goes away, battery manufacturing carbon footprint is added on top of the footprint from manufacturing of the vehicle, and the fuel cycles,” Sinha said. “And since these activities depend on electricity, the mix of electricity also matters to the overall carbon footprint. The more renewable the grid is, the less carbon footprint there will be. Here, the semiconductor industry has a role to play because to have that renewable energy, and given the periodicity of renewable energy generation, whether it’s solar or wind, you do need to have power electronics to convert that energy to use in the grid.”

Others agree. “For an internal combustion engine to move a vehicle down the road, it must convert the energy stored in the fuel into mechanical energy to turn the wheels and into electrical energy to power all the electronics (i.e. safety, comfort, emission controls) controlling the vehicle,” said Joseph Notaro, vice president of worldwide automotive strategy and business development at ON Semiconductor. “Any wasted energy not used for these purposes will just increase the vehicle fuel consumption and CO₂ emissions. One way to lower this wasted energy is by reducing the amount of electrical power dissipated in the car and reducing overall weight. Higher voltage power semiconductors are at the heart of new 48V architectures that provide significant fuel savings by enabling more efficient energy recuperation, and by driving large loads (pumps, compressors, power steering, etc.) more efficiently. Every mW counts, so improved efficiency of DC-DC converters, lower standby currents for power supplies, smarter data processing reducing the number of bits needed to be distributed in the car, are all contributing to increasing the vehicle fuel economy and reducing the amount of CO₂ emitted.”

More chips, less power
Semiconductors will play a key role in all of this, both in electric vehicles and those with internal combustion engines. And with different classes of electric and electronic systems in the car, there are opportunities for the technologies to be put to better use.

“Number one are standard electric systems like seat heating, air conditioning, wipers, and fans,” said Robert Schweiger, director of automotive solutions at Cadence. “These consume quite a bit of energy. Then, there are the car driving functions like power steering, anti-lock systems, electronic stability programs. This is much more the domain of semiconductors, and currently there are a few issues. First, there is an electronic control unit for each function. Second, there is a mix of technologies. For a power steering system, I’ve seen a presentation from a Tier 1 vendor showing what system has made the biggest impact on power savings, and it was the change from hydraulic power steering to a drive-by-wire power steering. Instead of always empowering the hydraulic system to keep the pressure up, there is an electric motor that is driven by a wire. That is what changes the direction of the car, but only while it is needed. You need energy for the motor, and eventually to steer the car. This is an important area with a lot of potential for innovation, and lots of those things are underway by the OEMs.”

There also are multiple functions under the infotainment umbrella, but those tend to be much lower consumers of power. “There’s a lot of stuff happening, but infotainment systems have already evolved to be quite integrated systems,” said Schweiger. “We always had powerful audio systems and navigation systems. Now, there are new systems coming online, such as AI-based speech or voice recognition and driver monitoring, but they do not consume so much energy.”

Fig. 1: Comparison of systems consuming power in vehicles. Source: Cadence/ADAC.de

“Semiconductors have helped make cars more efficient in terms of functions such as gas consumption where engines have certain patterns, and the semiconductors help to regulate certain things that go on, both in an engine, and within the car itself,” said Steven Woo, fellow and distinguished inventor at Rambus.

But those semiconductors have to become more energy-efficient, as well. “All the techniques the industry has been working on, both within a chip to do things like lowering voltages  — as well as what we do in memory and interfaces to reduce the power needed to move the data as quickly as possible — those are all things that help reduce the carbon footprint. It means you don’t draw as much energy from the batteries, and it means you may not have to recharge as often. That pushes all the way back into the source of the increase of the carbon footprint. The trajectory the semiconductor industry has been on for decades is exactly what we need to help reduce the carbon footprint, because all these things about integration, energy efficiency, better interfaces, better memory, and better chips are integral to reducing the carbon footprint.”

Chips are increasingly important in all functions within a vehicle, from safety and driver assistance systems, all the way to battery management and electronic drivetrain control. Automatically adapting the speed to the current traffic situation and looking ahead to road blocking situations is enabled by more sensors, data processing and communication of cars with each other as well as with the infrastructure.

“This is only possible with low-power, high-performance semiconductors, including memories for storing high resolution maps, for instance. That leads to a reduced carbon footprint,” said Roland Jancke, head of department, design methodology at Fraunhofer IIS’ Engineering of Adaptive Systems Division.

According to a recent Strategy Analytics report, by 2027 EVs of all types will comprise about 40% of global light vehicle output. California has mandated that in 2035, all new vehicles sold must be zero-emission. The challenge is that automakers need to anticipate what customers will need at least seven years out, and that puts pressure on chipmakers to build some flexibility into their architectures.

“It’s clear that vehicles in general, and EVs in particular, are increasingly integrating greater semiconductor-enabled electronics capability, whether it is for immersive in-vehicle experiences, or to add safety capabilities through features like lane keep assist (LKA), or to manage drivetrains,” said Chet Babla, vice president in Arm’s Automotive and IoT line of business. “The biggest industry concern about the success of EVs — safety aside, which is a given — is ensuring maximum driving range for a given battery capacity to address consumer ‘range anxiety.’ Simply put, the electronics in EVs must be as power-efficient as possible for given workload demands to ensure battery capacity is predominantly available for the drivetrain to power vehicle motion, and not drained by the vehicle’s electronics before the vehicle has even moved. By deploying heterogenous semiconductor computing architectures that combine multiple compute elements, such as CPU, GPU, ISP, and dedicated accelerators, the processing efficiency for complex workloads such as forward vision, multi-screen graphics and battery cell management can be maximized, and so deliver optimal usage of the EVs battery capacity.”

Rethinking chips and architectures
Improving efficiency affects a long list of chips and systems. All of those need to be optimized, and that optimization needs to include both hardware and software, said Marc Serughetti, senior director of product marketing and business development at Synopsys. “Components of this optimization include digital, analog and power electronics components. Addressing requirements such as reducing costs, efficient battery management, maximizing range and performance, and module integration leads to increased system complexity, and as a result, new design and development challenges both on the hardware, software and system sides.”

That requires a lot of exploration, prototyping, modeling, and testing in order to find the best tradeoffs within a particular chip or system. Serughetti pointed to the following requirements:

• An integrated multi-discipline solution (power electronics system design, embedded software development, system testing, calibration) to serve a broad range of users including controls systems developers, application software developers, firmware developers, power electronics engineers, battery management system developers, motor drive engineers, reliability engineers, functional safety engineers, calibration engineers and system/software integration engineers;
• Ability to deliver application-focused model libraries, including power electronics, microcontrollers, and AUTOSAR software simulation;
• Multi-level fast simulation from abstract to high fidelity for detailed analysis;
• Debug, analysis and test for functional safety, hardware, software, variation, coverage, calibration; and
• Open interfaces (FMI, VSI, etc.) to integrate into existing automotive tools flows.

But that effort also extends to the overall approach to semiconductors in cars in the first place.

“The issue is with these rapid switching speeds,” said Willard Tu, senior director of the automotive business unit at Xilinx. “If you’re not able to harness them, then you’re not able to maximize the efficiency of the motor or the charging.”

Achieving those switching speeds requires a different technology. At least one carmaker reportedly has converted to silicon carbide transistors, which use big power IGBTs that are used to drive the motors. Specialized devices are able to parallelize the computations to close the timing loop to make sure that happens.

“From that standpoint, we’re starting to see successes with onboard charging,” Tu said. “And we’re starting to see successes with EV motors. The industrial sector has embraced silicon carbide a little bit faster because they’re willing to pay more. They’re lower volume, but they’re more about the technology, whereas the EV car manufacturers really want low cost. There will be a transition at some point because with silicon carbide technology, not only can you get a more efficient motor, you get a smaller motor, and it’s a smaller motor with lighter weight. That lighter weight means the vehicle is going to not be as heavy, so you’re going to get greater range. Ultimately, all of this benefits the consumer at some point.”

Eliminating or reducing redundancy can help, as well. While cars are truly becoming supercomputers on wheels, at the same time there’s less redundancy. “There’s more compute power, but it’s compensated by systems that are more elegant,” said Guillaume Boillet, product management at Arteris IP. “There is rationalization of the traffic, and of course, as the technology improves, over time the chips consume less and less, so it’s a balancing act.”

Software plays an increasing important role as well within the vehicle, even as the overall system grows in complexity. “Increasingly, we’re seeing things that were not been able to be controlled by software in the past, now being controlled by software. You’re seeing replacements of hydraulics and such things with smarter electromechanical systems, along with more centralized control to optimize the overall system,” Boillet noted.

Technology outside the vehicle
All of that happens inside the vehicle. There is a flurry of activity outside the vehicle, as well. In the United States, for example, the century-old power grid will need a major upgrade in order to charge vehicles the same way that gas stations do today.

To that end, the U.S. Department of Energy’s Office of Electricity has developed a Smart Grid concept that mixes power generated from natural gas with power generated from renewable sources. The plan relies on Phasor Measurement Units (PMUs), which are sensors to ensure that electricity continues to flow around outages and other problems that might occur. Included in the concept are large batteries to meet surges in demand.

“If you have to reduce the carbon footprint of charging these vehicles, you need a more renewable grid,” said Mentor’s Sinha. “With sharply decreasing battery prices, it is easy for automakers to put in increasingly bigger batteries. That’s why 60- to 100-kilowatt hour battery packs are becoming common. Still, with all these cars running around a lot of energy is being used. Yet 90% to 95% of the time our cars are parked. We carry a lot of ‘distributed energy’ in these vehicles. So by applying V2G technology, this can be leveraged.”

Another piece of the puzzle is a faster and more efficient communications infrastructure. 5G is expected to help by increasing the amount of data that can be moved using the same or less energy.

“5G has a tremendous role to play, and semiconductors for 5G hardware, but also software, especially the AI technologies that can help understand every user is different and every consumer behavior is different. How I’m using my vehicle may be very different from how you use yours; what is your charging preference versus my charging preference, and all that information, taking all those weather patterns; where the chargers are in the city we are living in, our infrastructure. All of those information variables are critical to chew upon, to bring a more reliable V2G technology, which is where AI and 5G fit in,” Sinha said.

To be sure, the semiconductor industry plays a foundational role within the automotive industry to reduce the carbon footprint.

Conclusion
The interplay between systems, and understanding how to make efficiency gains is a significant challenge because so much with a system depends on other systems in the vehicle.

“Now that we know which system is consuming in terms of how much energy, the important thing is to find a way to reduce the power consumption,” Cadence’s Schweiger said. “I can put a smaller battery into the car. If I have a smaller battery, I need a smaller generator. If I have a smaller generator, basically the wire harness gets thinner because I drive these currents through my wires. And then, if I have smaller wires, the car gets lighter, and for the same acceleration, I can use a smaller engine. If I have a smaller engine, I eventually can put in some lighter type of body construction, because the car gets lighter. I can use smaller breaks and so forth. It’s a spiraling effect, and that’s why some OEMs incentivize their development departments. If they can save one amp of power consumption for their system, then they can spend, for instance more money on other systems, because they are aware that power consumption is driving the cost up or down if you can reduce it.”

Yet another important consideration is the hundreds of ECUs within a vehicle. “By going to the next generation of EE architecture, which is a zonal architecture, the OEMs will heavily consolidate ECUs,” Schweiger noted. “That means if you have a multifunctional zonal controller, you can use this device to realize multiple functions. But the box itself as we know, semiconductors, do not consume a lot of power. So if we make them more powerful in terms of performance, using the latest process technology, sometimes the power consumption even goes down. And it can do more. so that’s another potential to save power in a car. It’s already underway with domain-based controllers, and will be leveraged much more going forward to the next generation architecture.”

All these improvements will result in cleaner vehicles that require less time and energy to be charged and can be driven for much longer ranges without any impact to the environment. The semiconductor industry is at the heart of this revolution with energy efficient innovations being engineered, and that is only going to continue.