Stanford’s team of scientists has developed the first step to wirelessly recharge vehicles.
Taking a road trip in an electric car is now a stronger possibility thanks to the team of scientists at Stanford University (SU).
In a recent study, the Stanford team wirelessly transferred electricity to a moving light bulb.
In doing so, scientists have contributed to a future where electric cars can recharge while being driven.
“We still need to significantly increase the amount of electricity being transferred to charge electric cars, but we may not need to push the distance too much more,” said Shanhui Fan, Professor of Electrical Engineering at SU.
The Study
The Stanford team based their study on work performed at MIT in 2007, which used what is referred to as magnetic resonance coupling to transfer electricity to a light bulb from 6.5 feet away, even with objects in between the bulb and the source.
Drawing from that achievement, the team at Stanford wanted to see if they could apply a similar system to send more power. They aimed to develop a method to recharge a moving vehicle at highway speeds.
The team worked to effectively transfer 10 kilowatts to a moving car from 6.5 feet away and found that a source coil with a 90-degree bend atop a metal plate could achieve this.
The transfer was at an efficiency of 97 percent—much higher than other wireless systems so far— and believed that with further tweaking they could achieve even higher efficiency.
It is still in the early stages, but the Stanford team has already filed for a patent on their system with plans to more toward further testing.
Wireless Charging
Major power plants use coils of wire between magnets to generate alternating currents and move electricity through wires, creating an oscillating magnetic field.
It’s in this environment that magnetic resonance takes place because the field also causes electrons to oscillate from nearby coils, which leads to wirelessly transferring power.
However, this does not come without challenges, considering the electricity can only continuously flow if certain parts of the circuits—such as the frequency—are manually tuned while the object moves.
The Stanford team addressed this issue by replacing the radio-frequency source with a voltage amplifier and feedback resistor.
With the newly added components, the system automatically figures out the right frequency without requiring human interference.
“Adding the amplifier allows power to be very efficiently transferred across most of the three-foot range despite the changing orientation of the receiving coil,” said Sid Assawaworrarit. “This eliminates the need for automatic and continuous tuning of any aspect of the circuits.”
The Impact on Electric Cars
Providing a more practical way for electric cars to recharge would not only lower their cost but also address concerns over their limited range.
According to the U.S. Department of Energy, there are only around 5,500 direct current fast charging stations* across the U.S. alone, and despite their being plans to add more, they remain impractical for long distance drives.
Apart from the limited amount of electric charging stations, electric cars take several hours to recharge fully.
However, with this new study, “the hope is that you’ll be able to charge your electric car while you’re driving down the highway. A coil in the bottom of the vehicle could receive electricity from a series of coils connected to an electric current embedded in the road,” added Fan.
This would be a total game-changer for electric cars considering they can only travel between 200-240 miles on a single charge.
“In theory, one could drive for an unlimited amount of time without having to stop to recharge,” said Fan.
The Next Step For Electric Cars?
Making electric cars easier to recharge means a boost in their demand, leading a boom in their industry.
Additionally, the higher amount of people driving electric cars means more contributors to a sustainable country.
Electric cars could become the standard vehicle, especially if solar power and other renewable energy sources are readily accessible for easy recharge along the highway system.
The development of recharging moving vehicles would also impact other industries that employ technology.
“We can rethink how to deliver electricity not only to our cars but to smaller devices on or in our bodies,” added Fan. “For anything that could benefit from dynamic, wireless charging, this is potentially very important.”
