Growing up, Omer Onar dreamed of being an astronaut and working in space science. Today he’s involved in the science of space—in this case the gap between a magnetic coil and an electric vehicle being charged with wireless technology.
Onar led the team that demonstrated a 20-kilowatt wireless charging system with more than 90% power transfer efficiency in a Toyota RAV4 at Oak Ridge National Laboratory (ORNL). He’s now busy scaling up the technology for a planned 100-kilowatt vehicle wireless charging demonstration at ORNL, with an eye towards the US Department of Energy’s (DOE’s) goals for extreme-fast charging levels of around 350 kilowatts.
Wireless charging is not a new concept—the capability was demonstrated on a small scale in the early 1900s by inventor Nikola Tesla. But any real practical use had to wait for the advent of power electronics that generate the strong magnetic fields necessary for large-scale use. The goal today is a wireless charging system that can recharge a vehicle in a few minutes, replicating the experience of gassing up a conventional vehicle at the pump.
One of the biggest challenges with the technology, Onar says, is that it’s not just a question of power electronics. “It’s a very multidisciplinary area,” he explains. “You deal with grid and power systems, electromagnetics, thermal management, and how to integrate the technology into vehicle systems, including communicating back and forth with the vehicle. The work involves several different engineering specialties.”
The 20-kilowatt system was the result of unique architecture, including an ORNL-built high-frequency inverter, high-frequency isolation transformer, vehicle-side electronics, and electromagnetic coupling technologies. The work was supported by DOE’s Vehicle Technologies Office.
Onar’s varied background has been essential to the task. He began his career at ORNL as a Weinberg Fellow focused on integrating solar energy into building loads and industrial sites—designing novel components for power inverters that are durable, lighter, and less bulky. That task likewise relied on his doctoral work in electrical engineering, in which Onar researched hybrid energy storage systems and grid interface converters for electric vehicles.
Onar became involved in the early vehicle wireless charging work at ORNL after it was suggested he’d be a good choice to help program the technology’s main controllers. Onar ended up working on the project full time and in nearly every science area, eventually transferring into the lab’s Power Electronics and Electric Machinery Group.
Minding the gap on UPS’ big brown trucks
The researcher is also leading a project to install 20-kilowatt bidirectional wireless charging systems on the big brown trucks of the United Parcel Service (UPS), with the ability to move electricity in either direction—either charging the vehicle or transferring power back into a building or the power grid. One interesting challenge is that the delivery trucks sit higher off the ground than passenger vehicles, so the air gap is greater. Onar and his team must design a system that will transfer electricity efficiently across a wider distance—an 11-inch air gap vs. the roughly 4- to 6-inch gap for a passenger vehicle. The team is working on solutions to increase the strength of the magnetic field to deal with the greater power transfer distance.
In other work, Onar and his colleagues are examining the impact of the electromagnetic fields from dynamic wireless charging on connected and autonomous vehicle components. “Those vehicles have a lot of extra technology—laser scanners, radars, cameras, sensors, and communications systems from vehicle-to-vehicle and vehicle-to-infrastructure,” he said. “We’re studying how magnetic fields will impact those vehicles, and if there is an impact, how we can mitigate those effects with a shielding technology, the use of different materials, or advanced geometries.”
During his childhood in Turkey, Onar excelled in math and science and was encouraged in a technical career by relatives who were engineers and by an uncle who was an architect and university president. Helping one of his college professors write a book on computer programming piqued his interest in pursuing graduate studies. “I enjoyed the research work and also writing out the results and reporting it for others to use,” he noted. Onar earned his bachelor’s and master’s degrees at Yildiz Technical University in Istanbul in 2004 and 2006 before moving to the United States to earn his PhD at the Illinois Institute of Technology.
“I enjoy being able to collaborate with people from other organizations at the lab to create unique solutions,” Onar said. “I’ve learned a lot that way. Just like wireless charging, I’m not focused on a single thing. I multitask a lot. When we first started designing our magnetic coils we had help from researchers working in fusion energy at the lab. And just recently we’ve started using high-performance computing to help us optimize electromagnetic designs for wireless charging.”
“I can’t see myself ever getting to the point where it’s not challenging anymore; where I’m not learning something new and having fun,” the researcher added. “We have great resources and excellent capabilities in our people and equipment here.”
Away from the lab, Onar enjoys hiking in the Smokies, citing Abrams Falls and Rainbow Falls as two favorite trails, as well as water skiing, which he took up after a coworker introduced him to the sport.
If he could work on any project, Onar has a specific one in mind: to improve the operational efficiency of traction drive inverters, particularly at light loads. These devices convert the direct current from batteries to the alternating current that drives electric vehicle motors.
Onar also finds strong personal motivation is simply accomplishing tasks. “I like to get things done. When I need to complete an experiment or have a major proposal due, I might lose sleep getting it done. But instead of feeling tired the next day I actually am relaxed and feel great, because the task is accomplished,” he said.
ORNL is managed by UT-Battelle for the Department of Energy's Office of Science, the single largest supporter of basic research in the physical sciences in the United States. DOE’s Office of Science is working to address some of the most pressing challenges of our time. For more information, please visit http://energy.gov/science.
