Stanford researchers demonstrate new method for transmitting electricity wirelessly

Stanford University engineers have demonstrated a new way to wirelessly transmit electricity to multiple devices. The wireless power transfer system they developed can send electricity to electric vehicles, robots and drones as they move. The team said the technology needs to be scaled up to be able to power electric vehicles as they travel on highways or power robots on factory floors.

Wireless power transfer also has the potential to transmit power to drones while they're in the air. Stanford researchers Shan-Hui Fan and Sid-Asawawarit have demonstrated this technology in the past to wirelessly charge objects in motion, but it was too inefficient to be used outside of the lab. The team says their new research is an important step toward a practical, efficient wireless charging system for cars or robots.

Three years ago, researchers were able to develop a charger that can transfer power even when the distance to the receiver changes. This improvement was achieved by integrating an amplifier and feedback resistors that allow the system to automatically adjust the operating frequency as the distance changes. The downside of this technology is that it can only transfer 10% of the power that passes through the system.

The new technology developed by the researchers can transmit 92% of the power flowing through the system. This improvement was achieved by replacing the original amplifier with a more efficient "switch mode" amplifier. In the lab, the team can wirelessly transmit 10W of power over a distance of two or three feet. The system can be scaled up to transmit tens or hundreds of kilowatts of power required for a car. The system can quickly transmit power through a four-foot charging zone, enough to power a car traveling at 70 miles per hour. The team admits that there is a limitation, which is how quickly the car battery can absorb the power. The power can be transmitted through the human body without the person feeling the current and without any health problems.