Delphi is ready to cut the cord

January 27, 2012
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While Delphi is developing a wireless in-car charging system for mobile devices, the company also is producing a wireless charging system for everyone’s largest mobile device: their automobile.

The Delphi park-and-charge wireless system is patented, in production and being demonstrated. The system’s advanced technology was developed through a partnership between the Michigan-based automotive engineering firm and WiTricity Corp., which was begun by researchers at the Massachusetts Institute of Technology. They created the concept but for other and much smaller uses, such as wirelessly powering a flat-screen TV with a coil instead of an electric cord.

“They actually transmitted the power from the other side of the room to demonstrate the concept. Our president, Rodney O’Neal, saw that and asked us to look into it,” said Chris Burns, Delphi engineering director for North America, from his office in Troy.

At the time, the company was putting the finishing touches on a wired charging system for hybrid autos, which is now completed and pretty much the current standard for plug-in charging. “But we recognized that some people wouldn’t want to do that for a variety of reasons. It might be in a public place where those cords could be vandalized and taken for the significant amount of copper that is in the cables. The cables are pretty big and they carry a lot of power,” said Burns.

So Delphi asked WiTricity if it could increase the power load the wireless system carried. Instead of the three to 10 watts the researchers had successfully transmitted wirelessly, Delphi wondered if 3.3 kilowatts could be transferred. “They said ‘yes, it’s just that the coil would have to be bigger.’ So we started working with them to develop that,” said Burns.

The result of that collaboration is a four-component wireless system that uses highly resonant magnetic coupling, instead of the more traditional inductive coupling, to charge all-electric or hybrid autos. The four pieces are a charging controller, a power-source resonator, a power-capture resonator and a below-ground cable that runs from the controller to the power-source resonator, which some have referred to as a “wireless mat.”

The controller is connected to an electrical source and sends the power to the mat, which transfers it wirelessly to the power-capture resonator. The PC resonator, which is attached to a car’s underbody, is wired into an auto’s charging system.

“So you can either have a parallel system where you take that power capture resonator and run it right to the motor packs or the battery, or you can bring it into the existing onboard charger. That’s a wired charger. There is a wire in the car that goes down to the charging unit, and that charges the battery that runs the motor,” said Burns.

“So you can either run that resonator coupler in parallel to that, or you can run that into the charger. Right now, we’re running it into the charger so the OEM doesn’t have to develop two systems, one with this and one without this,” he added.

The controller actually communicates with an auto. It can determine when a charge should begin, how far along a charge is, how much power it has to provide and when a charging session is done. It can also send that information to an owner.

“There are a lot of people developing applications, like smart phone applications or a computer application, where someone could see on their phone the state of a car’s charging,” said Burns.

The PS resonator is 50 by 50 centimeters, weighs about 20 pounds, is 4 centimeters thick, and contains a specialized coiled wire that sends the power to the capture resonator, which is smaller, at 33 centimeters, and lighter, at 11 pounds. Burns said one way to envision resonant coupling is to think of an opera singer who hits a certain note that shatters a glass.

“Two coils are resonating at a certain frequency — about 145 kilohertz for this kind of an application. It’s very well matched so what you get is a highly tuned magnetic circuit, so you’re transmitting power very efficiently around the resonating coils,” he said.

That resonating action is the key element to Delphi’s product and the main reason the company feels it offers the best wireless system. Some Asian firms also are producing wireless chargers, but those systems are based on inductive coupling, which Delphi doesn’t believe is as efficient in transmitting power.

Burns said the difference between the systems is Delphi’s doesn’t require an owner to park a car as precisely as the one being developed overseas. If an owner lines up the resonators squarely, the Delphi system is 95 percent efficient in delivering a charge.

“We’ve achieved that goal. We wanted to get 95 percent efficiency and we have done that. You can be off 15 centimeters to the left or 15 centimeters to the right or 7 centimeters back, and you’ll still get 80 percent efficiency,” said Burns, who added that OEMs are looking into adding auto lasers to help with aligning the car. These would be similar to the sensors that assist with parking in tight spaces.

In contrast, Burns said inductive coupling systems require that a car be lined up much closer to the coils to achieve maximum efficiency, within about 2 inches, because they use a rod that sits inches up from the ground to transfer a charge. The Delphi PS resonator is wider, shorter and lies flat in the ground or in a garage floor, and the PC resonator can get an efficient power transfer even if an auto is 12 to 20 inches off from perfect alignment.

“Picture a can. You have to line up, pull in and park over a can, and so the clearance between those two is much less,” said Burns of the inductive system. “You’d have this thing sticking up in your garage all the time, almost like a sword handle sticking up out of the ground. If these are in a parking lot or something, you’d have to be careful that you didn’t hit it. If you hit it with a snowblade or something like that, you’d rip it up.”

Burns said Delphi has already refitted a few cars and demonstrated its system for OEMs. The firm also had another company make a battery pack that can be charged by its system. One of the autos is being demonstrated in Champion, Ohio, where Delphi produces the system.

“There are a lot of people that are interested in this technology around the world,” he said. “We think in the latter half of this decade — maybe as early as 2015 — you’re going to see this thing coming into production in automobiles, based on what the OEMs have said.”

Some businesses outside the auto industry might be interested in this technology, too. Hotels and restaurants may want to install a few of Delphi’s wireless chargers for customers. So might parking companies — like the city’s, which has installed wired charging posts. None would have to worry about the Delphi system being vandalized for the copper because the firm has cut out the plug-in cord.

“Whether it’s a restaurant or a hotel or whatever, they can provide that service to the customers,” said Burns. “Their business model might include that as something they offer as part of their marketing strategy.”

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