Advanced Thermal Management Design For Heavy-Duty Electric Vehicles

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Researchers look to develop advanced thermal management systems for power inverters in heavy-duty electric vehicles.

Electric vehicles are gaining attention due to their promise of reducing greenhouse gases emissions. Currently only light electric-vehicles are being focused on, but heavy-duty trucks make up 39% of greenhouse gas emissions in the transportation sector. Therefore, heavy-duty EVs are integral to decarbonization efforts, but vehicle components must be designed to handle more power while continuing to regulate operating temperatures. 

Researchers from National Renewable Energy Laboratory (NREL) in collaboration with John Deere have developed a state-of-the-art thermal management system to significantly increase the power density of silicon carbide (SiC) inverters within heavy-duty EV applications.

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Every electric vehicle, including heavy electric vehicles, requires power inverters for controlling the power flow between DC and AC electrical systems in order to run vehicle systems, accessories, and electric machines, such as motors and generators. A high-efficiency of these power inverters is necessary for electrification of heavy-duty vehicles. 

“The key to NREL’s design innovations for SiC thermal management is to improve the heat transfer coefficient, which allows this system to cool itself efficiently and continuously during operation with the engine coolant,” said Kevin Bennion, NREL senior researcher and thermal management expert. “This design facilitates an unmatched power density and keeps the system running safely and efficiently.”

The researchers developed a state-of-the-art thermal management system to optimize system efficiency while regulating operating temperatures of the SiC modules directly cooled with 115°C water-ethylene glycol coolant. This design enables an impressive heat-transfer coefficient of as high as 93,000 watts per square meter per degree Kelvin which is over four times higher than current commercial systems.

“The SiC inverter technology stands out among all competing technologies in terms of energy efficiency, fuel economy, performance, and system integration,” Bennion said. “With the premium cost of the SiC power converter, the market adoption of this new technology will likely take place where those factors are more important than the initial cost. We believe this inverter will have significant impacts in heavy-duty machinery, aviation, and military applications.”