Researchers at Imperial College London successfully test wireless airborne battery charging
Scientists have demonstrated a “highly efficient” method for wirelessly transferring power to a drone while it is flying. The breakthrough could, in theory, allow flying drones to stay airborne indefinitely - simply hovering over a ground support vehicle to recharge - opening up new potential industrial applications.
Although inductive charging has been feasible for decades, it has not yet been able to wirelessly power flying technology.
In the field
Researchers at Imperial College London removed the battery from an off-the-shelf mini-drone quadcopter drone, around 12 centimetres in diameter. They made a copper foil ring, which is a receiving antennae that encircles the drone's casing. On the ground, a transmitter device made out of a circuit board is connected to electronics and a power source, creating a magnetic field.
The drone's electronics are tuned or calibrated at the frequency of the magnetic field. As with wireless charging of EVs, when the drone enters the magnetic field an alternating current (AC) voltage is induced in the receiving antenna and the drone’s electronics convert it efficiently into a direct current (DC) voltage to power it.
They believe their demonstration is the first to show how this wireless charging method can be done efficiently with a flying object like a drone, potentially paving the way for wider use of the technology.
How efficiently has not been stated, but with some wireless chargers already claiming efficiency of around 90%, it is not beyond feasible to imagine a system with acceptable, if not negligible losses.
The technology is still experimental. The drone can only currently fly ten centimetres above the magnetic field transmission source, and the team estimates that they are one year away from a commercially available product. When commercialised they believe their breakthrough could have a range of advantages in the development of commercial drone technology and other devices.
While the use of small drones for commercial purposes and in surveillance is growing, there are a number of technical limits. The distance that a drone can travel and the duration it can stay in the air is affected by the availability of power and re-charging requirements – an issue which could be addressed with wireless power transfer, according to the team.
Dr Samer Aldhaher, a researcher from the Department of Electrical and Electronic Engineering at Imperial College London, said that: “There are a number of scenarios where wirelessly transferring power could improve drone technology. One option could see a ground support vehicle being used as a mobile charging station, where drones could hover over it and recharge, never having to leave the air.”
Professor Paul Mitcheson, also from the Department of Electrical and Electronic Engineering at Imperial, explains: "Imagine using a drone to wirelessly transmit power to sensors on things such as bridges to monitor their structural integrity. This would cut out humans having to reach these difficult to access places to re-charge them.”
Another application could include implantable miniature diagnostic medical devices, wirelessly powered from a source external to the body. This could enable new types of medical implants to be safely recharged, and reduce the battery size to make these implants less invasive,” he suggested.
The next stage will see team exploring collaborations with potential industrial partners.