As electrification makes its way into heavy-duty truck drivelines, the integration of the truck’s components will go even deeper than we see in today’s powertrains. It’s a result of moving to one electrical-power infrastructure as opposed to today’s trucks, which draw from diesel power to provide electrical energy.
“Any type of all-electric vehicle is its own little grid,” said Jeff Lowinger, president of Eaton’s recently established eMobility business, which focuses on three primary areas for both automotive and commercial vehicle customers: intelligent power electronics; power systems; and advanced power distribution and circuit protection. “You’re going to have different voltage demands on all-electric trucks. The highest is going to be to propel the vehicle—in the 600- to 900-volt range—and then a lot of accessories are going to be operating at lower voltages from 48-volt. There is no personal safety hazard for components running under 60 volts, so that provides better efficiency for the components.”
One of the components that is going to demand a deep level of integration is the transmission. While there are still plenty of questions surrounding the driveline structure, mostly in terms of electric motor placement, in Lowinger’s view, an electric truck is still going to require a transmission to provide both the needed power and desired efficiency.
“We believe that the transmission will still be a key enabler of range and efficiency to meet customer needs no matter what type of vehicle it is,” Lowinger said. “We don’t think direct drive will provide the needed efficiency and range, as well as performance.
“Think about the torque you need in certain profiles,” he continued. “If the truck is on a hill, you need high-torque capabilities. You’re not going to get that in a direct drive system. You’re also not going to get the efficiency in other application profiles. A transmission provides the efficiency and operating performance, torque-wise, you need in a performance profile.”
Ensuring that the transmission is properly tuned to the electric motor configuration is just as important as how closely paired today’s diesel engines are matched to transmissions. Lowinger explained how electric motors typically run at a specific torque speed. If there’s no gear box to change the speed at which the motor is running, as in the case of direct drive systems, then the amount of time the electric motor runs within the proper efficiency band will be limited. Consider how today’s automated manual transmissions are optimized to put the diesel engine in the most efficient RPM range. The same concept can be applied to an electric motor-driven vehicle. After all, you don’t want to have the charge the batteries more than you have to just as you don’t want your trucks stopping to fill up on diesel too often.
Lowinger explained that as electric drive systems are developed, efficiency and performance losses, seen both in acquisition cost and ROI through efficiency, would come at the expense of how components are connected and blended with the mechanical systems.
“If you’re trying to piecemeal component by component without understanding how they integrate, then you’re not going to find an efficient solution,” Lowinger said. “In the end, you have to take a top-down view of the problem you’re trying to solve; you have to have the right level of competency on your team. That’s where early engagement with a supply base that can help you think through these solutions would be beneficial because the components are so connected.
“The time is now to start,” he stressed. “There’s a lot of activity going on within electrification. You’re not late, but you’re not early. There’s a lot of opportunity to take advantage of technologies that will help you meet the GHG regulations in the 2024 time frame.”
