A system delivers electricity wirelessly to a moving target

 Imagine cruising down the road while your electric vehicle gets charged, or having a robot that doesn't lose battery life while it moves around a factory floor. That's the sort of potential behind the newly developed technology from a team at Stanford University.

This is a significant step toward a practical and efficient system for wirelessly recharging automobiles and robots, even when they are moving at high speeds.

Wireless electricity transfer relies on generating oscillating magnetic fields that can then cause electrons in a conductor to also oscillate at a particular frequency. However, that frequency is easily messed up if the device is moving. Your smartphone needs to be sitting perfectly still on its charging mat, for example.

What Stanford scientists did in 2017 was set up an amplifier and feedback resistor loop that could change the operating frequency as the receiving device moved. At that stage though, only 10 percent of the power moving through the system was transmitted.

Now, they've got it up to 92 percent. That huge boost in efficiency is down to a new 'switch mode' amplifier – a more precise solution, but a far more complex one.

The basic idea is by adjusting the resonating frequency coming from the charger as the device moves around. Right now the system can transmit 10W of power across a distance of up to 65 centimeters, but the researchers say there's no reason why it can't be quickly scaled up.

An electric car would need hundreds of kilowatts to charge it, but the system outlined here is fast enough to provide it, if it were built into the road surface, for example. The only limitation would then be how quickly the car's batteries could absorb the power as the vehicle sped past.

Other potential uses are with robots that can be charged up by pads in the floor of the environments they're operating in, or with drones that can pass over roof surfaces during their journeys to stay charged up.

Being able to not only beam electricity wirelessly but also to beam it to a moving device could eventually revolutionize the way our gadgets work, and the way we travel.