BMW Begins Trials of 100 kW Multiphase Wireless Charge

BMW has started field testing hardware for multiphase wireless charging of electric vehicles in partnership with Oak Ridge National Laboratory and HEVO Inc. The programme moves BMW's wireless-charging work beyond conceptual demonstrations and into practical, on-vehicle trials.

Researchers at Oak Ridge National Laboratory have demonstrated wireless charging of a passenger electric vehicle at 100 kW with 96 percent efficiency in laboratory conditions, a power density the lab describes as eight to ten times higher than traditional single-phase coil systems. The new design uses rotating magnetic fields across multiple phases rather than relying on a single-phase induction coil.

Technology, partners and practical benefits

Multiphase coils generate a controlled, rotating magnetic field that enables higher power transfer and improved efficiency. Oak Ridge researchers say the approach increases power density while reducing thermal stress and the voltages imposed on the inverter, rectifier and other power-electronic components, which can ease hardware demands on the vehicle and charging system.

HEVO, based in New York, contributes its Journey software platform and Rezonant charging equipment, which meet UL and SAE standards, bringing operational experience relevant to commercial fleet deployment. Removing a physical cable is not only a convenience for drivers; it is also an enabling feature for autonomous vehicles, allowing vehicles to charge without human intervention.

With hardware field trials now underway, BMW has moved ahead of rivals such as Mercedes-Benz and Audi, which to date have limited their wireless-charging efforts to initial concept demonstrations.