A new silicon carbide (SiC) inverter developed by NREL power electronics researchers will increase the range of U.S. military ground combat vehicles by 200 percent while being only a quarter the size of previous-generation technology. Photo by Army Sgt. Tru Thao.
To design the cars of the future, you might think that you need to rethink the entire system. But sometimes rethinking a component can lead to radical results.
To modernize the U.S. ground combat vehicles, the National Renewable Energy Laboratory (NREL) was selected to redesign a key component: the traction inverter, which controls the flow of electricity between the vehicle’s battery, engine, and transmission. The new silicon carbide (SiC) powertrain will double the Army’s vehicle range in a footprint one-fourth the size of its predecessor.
The three-year, $6 million project is fully funded by the Defense Energy Innovation Office, Energy Capabilities Improvement Fund (OECIF). The project will be led by the U.S. Army Combat Capabilities Development Command (DEVCOM), and technical expertise will be provided by researchers from NREL and the Army Research Laboratory (ARL).
NREL researchers will apply their expertise in power electronics thermal management research to thoroughly test the innovative PICHOT cooling system. Image by Dennis Schroeder, NREL
The inverter will be designed, manufactured, and characterized in-house at NREL, and then evaluated at the U.S. Army Ground Vehicle Systems Center Test Facility. Its modular design allows it to be installed on a range of different hybrid ground combat vehicles, from light and medium wheeled vehicles to Abrams tanks and Stryker main battle tanks. Silicon carbide semiconductors and new thermal management will provide unprecedented power density, allowing vehicles to travel longer distances using less fuel.
“Any innovation we introduce into PICHOT will be an achievement,” said Brian Miller, an energy systems engineer at NREL’s Center for Energy Security and Sustainability, who will help lead the PICHOT project. “We’re going to add six innovations.”
To create PICHOT, NREL Power Electronics reimagined nearly every aspect of traditional power inverters.
The researchers first looked at the leading traction inverter currently used in U.S. Army ground combat vehicles: the 200-kilowatt Zeus inverter developed by DEVCOM for high-power applications. Then, based on NREL’s world-leading research in power electronics thermal management, they identified all the components that could be eliminated from the previous-generation technology — from cooling equipment to connectors.
Since traction inverters are often mounted next to other heating elements inside a combat vehicle, they must withstand high operating and ambient temperatures. This usually requires that they be equipped with a powerful cooling system, such as cold plates or coolant reservoirs.
PICHOT does not require any powerful cooling systems. Instead, it will connect to the existing engine cooling system, eliminating the need for additional coolant loops. So, unlike traditional silicon-based inverter systems that virtually fail at operating conditions above 70°C, PICHOT is capable of operating at full power at 105°C.
NREL’s Brian Miller will facilitate the lab’s contributions to the project. Image courtesy of NREL’s Gregory Cooper
Best of all, PICHOT uses 53 percent less fuel than existing technologies, meaning Army vehicles can stay on the battlefield nearly twice as long before needing to refuel. With hybrid engines and EMI shielding, Army ground combat vehicles will be quieter, safer, have greater range, and perform better than ever before.
“NREL has a highly skilled thermal management research group,” said Faisal Khan, a principal investigator in power electronics at NREL’s Center for Integrated Mobility, who will serve as the project’s principal investigator. “Given the complexity of this project — developing a traction inverter with high power density and tight thermal management that can operate in extreme conditions — we are well positioned to tackle this challenging task.”
NREL’s Faisal Khan will lead the lab’s contribution to the project and serve as principal investigator. Image courtesy of Agata Bogutskaya, NREL
PICHOT will take three years to design, build, and evaluate. During the first year, NREL researchers will build a computer model of the inverter and simulate its operation in the real world to ensure it works as planned. Then they will build it using a comprehensive prototyping process in the lab and demonstrate its performance compared to other standard Warfighter vehicles.
Finally, the designs will be presented to manufacturers at an upcoming industry day. The final design will be mass-produced and potentially deployed on various US Army ground combat vehicles.
As the Army prepares to implement a climate strategy to match the nation’s transition to low-emission vehicles, it will find that new clean energy solutions will provide more power, reliability and sustainability than ever before.
Learn more about NREL’s research in sustainable transportation and mobility, including its special focus on advanced power electronics and electric machines. Stay up to date by subscribing to NREL’s quarterly transportation and mobility research newsletter, Sustainable Mobility Matters.
The National Renewable Energy Laboratory is a national laboratory of the U.S. Department of Energy’s Office of Energy Efficiency and Renewable Energy and is operated by the Sustainable Energy Alliance, LLC.
Post time: Dec-29-2024