Randy Sumner takes the hockey puck- like device and holds it several inches above a pad. The light on the device instantly turns on.
“Pretty cool, huh?” says Sumner, Delphi’s director of global hybrid vehicle business development.
Very cool. Even cooler was the nearby Think City EV parked over a much larger pad. Electricity wirelessly flowing from the pad powered a display sign perched on top of the car.
Look Ma! No wires!
Seven months after partnering with WiTricity of Watertown, MA, Delphi unveiled the fruits of their work at the Society of Automotive Engineers (SAE) annual conference in Detroit: a prototype car equipped with WiTricity’s technology that uses magnetic waves to wirelessly transmit electricity.
WiTricity, founded by MIT physics professor Marin Soljačić in 2007, has designed a transmission coil that connects to a small electronics module and converts the traditional electrical current found in a home or office to a higher frequency and voltage, to create an oscillating magnetic field around the coil. If a separate coil designed to resonate to the same frequency is close enough to the source, power is transferred between the two coils.
The charging system developed by Delphi and WiTricity would enable cars powered with electricity to reboot without having to plug into a power source via a cord. It would only require cars to park over a wireless energy source on the floor of a garage or embedded in a paved parking spot, which would then transfer the power to the vehicle’s battery charger.
The idea of wireless electricity is not new. Until now, the biggest problem has been finding a way to retain enough power in the transfer process.
The prototype, Sumner says, generates about 95 percent efficiency, meaning only five percent of the power being generated gets lost in transmission. Delphi hopes all cars equipped with the technology will get at least 90 percent. The pad powering the Chevy prototype was transmitting about 2.6 kw, or 16 amps, of electricity, about the equivalent of Delphi’s current Level 2 wired chargers.
Sumner says WiTricity’s technology enabled Delphi to design much smaller coils and achieve greater distance between the bottom of the car and the charging pad. In theory, this could allow bigger trucks and vehicles to also use the technology.
In an interview, Andrew Brown, Delphi’s executive director and chief technologist, says wireless charging will go a long way to boosting the popularity of electric cars. Wireless charging pads could be installed in home garages, parking lots, offices, shopping centers, he says.
“It will eliminate this range anxiety,” says Brown, referring to consumers who worry they will run out of juice before finding the next charging station. Also, he says, “The average consumer is not accustomed to electric cars. [They worry] ‘Am I going to get dirty?’ or “Will I get electrocuted?'”
Wireless charging helps with both those issues. All consumers have to do is “park and charge,” Sumner says.
But Delphi still faces a long road from lab prototype to mass production. The company needs to work with OEMs (original equipment manufacturers) to figure out how to best integrate WiTricity’s technology into cars.
Delphi envisions a car that can be charged both by wired and wireless charging stations. The company also needs to find ways to shrink the electronics and reduce overall cost.
Delphi officials, however, are confident in the technology. They estimate the first cars using it will roll of the assembly lines in 2014 or 2015.
“This is real,” Sumner says. “This works.”
