Strongly coupled magnetic resonance is a wireless inductive technique that enables high energy transfer over large distances. This technique is used in wireless charging for electric vehicles. The charging equipment is made up by two different units, a sender placed in the ground at a parking space and a collector mounted underneath the car. A coil in the sender generates a magnetic field that induces an electric current in a coil in the collector. The induced current is then used to charge the battery in the car. To get high efficiency the frequencies of the sender and the collector must be coupled. This, so called resonant coupling, occurs when the natural frequencies of the two units are approximately the same. When this happens the two units can exchange energy through their oscillating magnetic fields, without losing too much energy to the surroundings.
Do you want to know even more about strongly coupled magnetic resonance; see Energiöverföring starkt kopplad resonans (PDF, in Swedish).
Wireless charging also of great importance for the plugin hybrids: The drivers of plugin hybrids have the choice to run their car on electricity from a rechargeable battery or to use an alternative fuel, like gasoline or diesel. The batteries in plugin hybrids are quite small and hence needs to be recharged relatively often. A risk is that drivers of these cars don’t use the electric drive line as much as they could, because the charging circumstances are too complicated to weigh out the advantages of using electric power. It is believed that by simplifying the charging of the car the drivers would charge more often and therefore also use the electric drive line more frequently. Wireless charging could be that simpler charging solution that gives the extra push to the plugin hybrid car drivers to primarily use the electric drive line and hence get the full advantage of their plugin hybrid.