Volvo unplugs plug-in hybrids and e-cars

October 24, 2013 // By Christoph Hammerschmidt
Electromobility still lacks of acceptance, and one major reason for this is the lack of standards for the charging plug. Now it seems like a solution becomes realistic - through a technology that has its roots in consumer electronics. A common standard however is still years away.

Volvo has been a partner in a research project that has studied the possibilities of inductive charging for electric vehicles – and the results show that this technology for transferring energy via an electromagnetic field has a promising future. Inductive charging has the potential to make a vehicle independent of mechanical connector designs.

Inductive charging uses an electromagnetic field instead of a cord to transfer energy between two objects. An induction coil creates an alternating electromagnetic field from a charging base station. A second induction coil in the portable device picks up power from the electromagnetic field and converts it back into an electrical energy that charges the battery. This technology is common in electrical home appliances such as electrical toothbrushes but is not yet commercially available to charge electric cars.

“Inductive charging has great potential", believes Lennart Stegland, Vice President, Electric Propulsion System at Volvo Car Group. "Cordless technology is a comfortable and effective way to conveniently transfer energy. The study also indicates that it is safe,” Stegland however pointed out that there is not yet any common standard for inductive charging", adding that the Swedish carmaker will continue its research and evaluate the feasibility of the technology in its hybrid and electric car projects.”

With the technology evaluated in the study, a charging plate is buried in the ground, for instance in the driveway at home where the car is parked. The charging plate consists of a coil that generates a magnetic field. When the car is parked above the plate, energy from the plate is transferred to the car's inductive pick-up. The energy that is transferred is AC; it needs to be converted into DC in the car’s built-in voltage converter, which in turn charges the car’s battery pack. Charging a battery pack of the size fitted to the Volvo C30 Electric, 24 kWh, takes about 2.5h, if the battery is entirely discharged. The charging system been