The plus side of electric vehicles, aside from being emissions-free, is the fact that you never have to fill them with gas. The negative side is that filling a car with gas takes only a few minutes, whereas a full battery charge-up usually takes hours. If you’re just traveling to work locally and can charge your vehicle overnight at home, it’s not a problem. However, if you want to drive a long distance, you’ll have to set aside time to charge the car every one to three hundred miles, depending on the model.
Now, imagine if you could drive along a highway that wirelessly charges your vehicle as you drive. That’s a technology that researchers at Stanford University are working on. The wireless charging technology would have to be installed into the road so that electric vehicles driving over them could charge their batteries on the go. And while wireless charging pads do exist already, they require the car to be parked above them, with only a few feet separating the battery from the technology.
The biggest challenge is that when the distance between the source and the receiver is continuously changing, it weakens the charge. To overcome this problem, the Stanford researchers built a system that incorporated a “switch mode” unit and feedback resistor, which produced an operating frequency that could automatically adjust as the distance between the moving object and the charger changed.
After years of tinkering with the circuit, they finally came up with a configuration that managed a transmission efficiency of 92%. Their prototype transmits only 10 watts of electricity wirelessly over a distance of up to three feet, but they say it can be scaled up to supply power to a fast-moving vehicle.
Electrical engineer Shanhui Fan, one of the researchers that developed the technology, said:
“This is a significant step toward a practical and efficient system for wirelessly re-charging automobiles and robots, even when they are moving high speeds. We would have to scale up the power to recharge a moving car, but I don’t think that’s a serious roadblock. For re-charging robots, we’re already within the range of practical usefulness.”
The engineers see the first real-world application of this technology being in warehouses to power robots for continuous operation and on rooftops to keep delivery drones in the air all day. The highways would be later on down the road as the process of installing them will be much more complicated than embedding them into the floor or roof of a building. For now, however, it remains a project in the lab.
