Wireless charging is coming, especially for electric vehicles, and copper is an essential part of the solution.
A wireless charging system consists of fixed and mobile modules. In the case of leading wireless-charging technology company, WiTricity, the fixed part has a wall mounted power converter that changes normal mains electricity to the much higher frequency of 85 kHz.
This high-frequency power is sent to a fixed ground pad mounted on or under the pavement where a copper coil generates a magnetic field. The mobile part is attached to the underside of a car or SUV where another copper coil intersects the magnetic field and, using power electronics, transforms it into DC power to charge the vehicle’s battery.
This so called magnetic-resonance-charging technique can achieve grid-to-battery efficiency of up to 94%, which is equivalent to a wired connection.
The fixed charging pad contains about 20 meters of 5mm diameter copper wire wound into a 65cm x 50cm rectangular coil. The copper wire is unusual: it is made of about 1000 strands of 0.1mm diameter wires woven into a pattern that reduces electrical losses during high-frequency operation. A similar but somewhat smaller coil is affixed to the vehicle.
According to WiTricity, wireless charging will require about 4 kg of copper per passenger car.
Wireless charging is an important component in the transition to a future where electric cars are predominant. High-power, high-speed chargers may be necessary for those traveling long distances, but for normal daily driving, the ability to easily top up a battery while shopping, working, or visiting a restaurant is a welcome convenience.
Take a look at Witricity: http://witricity.com
