APEI Improves Hybrid Battery Charging for Hybrid, Electric Cars

Driving a vehicle with a battery that charges and runs off electricity is considered to be an environmentally friendly choice.

It can also wind up being a time-consuming and inconvenient choice. Efficiency of converting power from the wall to the car isn’t maximized by available technology. Charging stations can be difficult to find. Additionally, the charger — the component inside the car that converts the electricity into power to run the car — tends to be bulky, weighing down the vehicle and potentially leaving less cargo space for the driver.

Figuring out how to improve those issues was the duty given to Arkansas Power & Electronics International and four partners working on a nearly $4 million grant from the Advanced Research Projects Agency/U.S. Department of Energy. APEI, a company located in the Arkansas Research & Technology Park in Fayetteville, is in the final year of the three-year grant, and while advances made on the project aren’t ready for mass production so far, the result is a smaller, more efficient charger for hybrids.

Ty McNutt, director of business development for APEI, said progress has been positive. APEI, along with Toyota America, the University of Arkansas, Oak Ridge (Tenn.) National Labs and Cree Inc. have been working to develop new technology for charging hybrid batteries since September 2010.

“What we are trying to do is leapfrog existing technology,” McNutt said. “You want to go past the next generation. So there are really hard goals, hard milestones you want to hit. We have hit those so far.”

More efficient charging is possible because of silicon carbide technology from Cree Inc. of Durham, N.C., a leading manufacturer in the field. Similar to the way that LED lighting is more efficient — and gives off less heat — than traditional incandescent bulbs, the silicon carbide chips produced by Cree make it possible to develop a charger that is smaller but still produces the power needed to charge the battery of a car like Toyota’s Prius.

A precipitous drop in the price of a key component of the chargers has made the improved chargers economically feasible. A single chip, which is a little larger than a postage stamp, used to cost $100 or more. Now they can be bought for less than $20.

“The cost of semiconductor devices has previously been a major inhibiting factor,” said Bret Whitaker, lead electrical engineer on the project with APEI. “That helps when you start talking about a manufacturer’s margins.”

With silicon carbide chips as a cost-effective option, APEI and its partner were then able to turn their attention to incorporating the technology into the new charger.

Lighter, Better

Dave Grider, program manager at Cree, said the results of the nearly finished product have been impressive. APEI’s charging device provides nearly triple the power of the standard Prius charger and is about 10 pounds lighter. Efficiency has improved by about 5 percent.

“When I saw it, I was just blown away,” Grider said. “It was really exciting. As a technology guy, you can see all the data behind an idea, but to actually see the physical object that had been created, it was great.”

McNutt said it is too early to tell what the increased efficiency and smaller size will mean for consumers, but there will be a benefit. They’ll have a car that takes less time to charge and generates less heat during the conversion process. That means the cooling system can be eliminated from the in-car charger, making it possible for a smaller component in the car. Less weight and less charge time should reduce the amount spent on fueling the vehicles.

These meet the objectives outlined when the grant was obtained from the Department of Energy. Ultimately, the goal is to improve the quality of vehicles that run on electric batteries, decreasing fuel consumption, while “jumpstarting” growth in the electric vehicle industry.

“Now that we have a functional prototype we can look at what that means numbers-wise,” McNutt said. “But you can imagine that decreasing the weight of the vehicle will mean a lot when it comes to gas mileage.”

Feedback for the project has been strong. APEI has shown off its work across the country, including at the 2013 ARPA-E Summit in Washington, D.C., where APEI team members visited with U.S. Secretary of Energy Steven Chu. A trip to Toyota headquarters in Japan also allowed APEI to showcase its improvements.

“It’s really enabled us to showcase what we can do as an Arkansas-based company,” McNutt said. “We’re advancing the state of the art in high-powered electronics and manufacturing them right here in Arkansas.

“This is proof it can be done here. This particular charging unit, the mechanical structure and the packaging structure were designed all in house, in Arkansas. We did the testing, the prototyping and the integration in the vehicle. We have the capability of manufacturing these units in Arkansas.”