The Hughes Aircraft Company of Los Angeles has filed a string of patent
applications in Europe on a system which could make recharging electric
vehicles as straightforward as refilling a car with petrol at a pump. The
heart of the system, described in EP 552 736/7/8, is an inductive coupler
based on technology developed by Hughes for US Navy submarines. The vehicle
has an input connector, formed from two flat circular jaws, with a copper
wire coil sealed inside each jaw. The jaws clamp together to secure a matching
ring which also contains a coil connected to the charging power supply.
There is no direct electrical connection.
When alternating current is fed through the output coil it generates
a magnetic field, and when this coil is placed between the coils of the
input connector an alternating current is generated, which recharges the
battery. At mains frequencies, 60 hertz in the US, the transfer efficiency
is low, so the Hughes system cranks up the supply frequency to 40 kilohertz.
This increases transfer efficiency a hundredfold. Test systems pumped 6
kilowatts through the coupler.
