At the US Department of Energy's(DOE) Oak Ridge National Laboratory, researchers are developing knowledge and technologies that accelerate the deployment of new vehicles and efficient transportation systems powered by domestic, renewable, clean energy.
Many of these innovations were featured recently alongside ORNL’s 3-D printed Shelby Cobra at the North American International Auto Show in Detroit. Below is a sampling of the technologies included in the display.
Researchers are creating inverters that are lighter, more powerful, and more efficient using novel semiconductors and unique designs enabled by additive manufacturing. The first prototype inverter featuring wide bandgap materials and 50% printed parts demonstrated an operating efficiency of nearly 99%, surpassing DOE power electronics targets and setting the stage for more innovative designs that use these materials and manufacturing capabilities to fullest advantage.
ORNL is improving the fuel efficiency and extending the range of miniature engines for remote-controlled airplanes, which could be implemented in military surveillance systems. Researchers used additive manufacturing capabilities to print the engine head out of titanium and to install special sensor ports. Engine, fuel, and emissions R&D encompasses projects like this aviation engine and focuses on new technologies for light- and heavy-duty vehicles.
Current projects are focused on developing novel power packaging techniques that exploit the superior attributes of wide bandgap semiconductor materials. For example, this highly integrated power module package features double-sided cooling and three-dimensional, planar power interconnection. The novel design improves efficiency, power density, system cost savings, and ease of manufacturability.
Using the advantages of additive manufacturing, researchers are developing novel concepts and prototypes that increase efficiency and reduce component weight. Electric drive technologies are a primary area of focus for exploring new geometries enabled by 3-D printing. These printed motor pieces are an example of the development underway for additively manufactured vehicle technologies.
ORNL is developing technologies to increase the availability of carbon fiber and composites. R&D focuses on low-cost raw materials such as renewable woody plants and more efficient manufacturing methods such as microwave assisted plasma processing. At ORNL’s Carbon Fiber Technology Facility, textile acrylic fiber—like that used in socks and sweaters—is converted into carbon fiber for use in lightweight, high strength components for vehicles and other applications.
Composite materials inherently absorb more energy than other materials such as steel and aluminum. They can be used to design safer cars. Researchers have the capability to engineer 3-D mesh structures that create multidirectional crash zones for increased driver safety. Specialized equipment and expertise at ORNL make it possible for industry to obtain data on the energy absorption of specific designs.
Novel concepts for electric motors are designed to reduce or eliminate the use of rare earth materials while maintaining high power density, specific power, and efficiency. Most electric and hybrid electric vehicles on the road today have motors that use rare earth permanent magnets. The US currently imports most rare earth materials, so researchers are focusing on this area as a matter of national energy security.
This patented 55kW current source inverter takes direct current and converts it into alternating current, boosting the voltage by up to three times and enabling electric vehicle motors to operate at higher speeds. The technology offers improved durability and power range in a smaller package, which enables reductions in battery size, saves costs and weight, and increases fuel economy. New Hybrid Technologies has licensed the technology.
Researchers are developing battery technologies that will extend battery lifetime and range, reduce battery size, and increase cost savings for America’s drivers. Water-based processing for lithium-ion batteries is a good example. This technology maintains battery capacity while reducing costs and benefiting the environment through the use of deionized water in place of expensive, toxic, flammable processing solvents.
Highly conductive, durable anion exchange membranes for use in alkaline fuel cells (AFC) are under development. AFCs use non-platinum catalysts, which significantly reduces fuel cell cost. Typically, AFCs have lower power density than other fuel cells, but these new membranes could address that issue by increasing the energy-producing movement of ions across the membrane.
ORNL is developing steel-concrete composite underground tanks for storage of hydrogen at fueling stations. Using friction stir welding technology, researchers are creating stronger vessels capable of withstanding high pressures (875 bar) with long-term durability. For hydrogen storage onboard vehicles, researchers are working with new materials and processes to make low-cost carbon fiber for use in high-strength vehicle storage tanks.
Dissimilar metal joining is a critical technical barrier for use of lightweight materials such as magnesium, carbon fiber composites, and new alloys in high-volume production of multimaterial vehicles. ORNL is developing a variety of new joining technologies to facilitate lightweighting, including ultrasonic welding, friction stir welding, and friction bit joining. These methods overcome the physical and chemical differences in individual materials to create high strength bonds.
ORNL developed a new type of friction stir welding called Multilayered Multipass Friction Stir Welding that eliminates limitations on the thickness of structures. Tensile tests show this revolutionary solid-state joining process creates welds that are stronger than the original materials. Different materials can be incorporated into the weld to tailor the composition and properties of the welded region. ORNL is applying this technology to the development of steel-concrete composite underground tanks for hydrogen storage.
Friction bit welding combines the advantages of self-piercing riveting with frictional heating and metallurgical bonding of sheet metals. It is especially suited for joining dissimilar metals where the differences in chemical make-up limit the effectiveness of traditional joining methods to create strong bonds. The addition of the mechanical bit facilitates bonding and increases the strength of the weld. ORNL is collaborating with industry and university partners to use this technology in lightweight vehicle applications.
Ultrasonic welding uses high frequency acoustic vibrations to create a solid-state weld. There are no other bolts, nails, soldering materials, or adhesives necessary to bind the materials together. This technology is particularly good for softer, lighter materials such as aluminum, magnesium, and polymers. ORNL works with industry to evaluate the strength of ultrasonic welds made with new alloys.
ORNL has developed wireless charging technology that can charge an electric vehicle battery with the same speed and efficiency as standard plug-in charging. Charging coils on the ground transfer energy across an air gap to the coils attached to the underside of the vehicle. This inductive charging process uses a magnetic field that emits less radiation than a laptop computer. Researchers have retrofitted a Toyota Prius with this technology.
Using additive manufacturing, researchers printed a housing made of heat-resistant polymer for the wireless charging coils and embedded the technology into a demonstration component. The charging coils are also installed on the undercarriage of the 3-D printed Shelby Cobra, illustrating how wireless technology can be integrated into electric vehicles.
Wireless charging while in motion over electrified roadways would enable drivers to charge their vehicles on their daily commutes, expand electric vehicle range, and allow fuel economy gains through downsizing of vehicle batteries. Researchers have demonstrated dynamic wireless charging using a small GEM vehicle. Further development of this technology is underway in collaboration with Toyota. ORNL and partner Evatran are integrating this capability into a small fleet of Toyota vehicles.
Oak Ridge National Laboratory is managed by UT-Battelle for the Department of Energy