by Bennett Daviss
Engineers at Stanford University have created a way to recharge electric vehicles wirelessly as they move that carries an efficiency of 92 percent, up from 10 percent that previous methods achieved.
Recharging an electric vehicle wirelessly involves creating a magnetic field that activates magnetic coils in the vehicle. But that only works if the frequency of the field stays the same. In practical terms, that means the distance between the energy-sending and energy-receiving points has to stay the same – the vehicle can’t move.
The Stanford group has built a feedback loop into the recharging system that maintains the right frequency as the distance between the vehicle and the energy-sending point changes.
The key is using a “switch mode amplifier,” a fussy piece of equipment that produces frequencies at high efficiency only under very precise conditions. The researchers invested more than two years of trials to get it right.
Sending the energy takes a few thousandths of a second, only a fraction of the time a vehicle traveling at 70 mph would take to cross a four-foot charging plate, the researchers say.
The technology also could easily be scaled up to meet the demands of highway travel.
The system won’t be commercialized for years, however, as roadway infrastructure would need to be built. That is likely to happen gradually as sections of existing highway are repaved or refurbished after the technology has passed full-scale tests.
Meanwhile, the system can be used to continuously recharge robots shuttling around factor floors or drones that could swoop down, hover over a charging plate for a few seconds, and then fly off to make their next Amazon delivery.
TRENDPOST: A wireless technology that charges moving EVs is likely to be practical only after EVs have gained a large enough market share to force governments’ road departments to make the investment. That puts the technology’s deployment at some time after 2030.
When that happens, the last vestiges of corner gas stations or their descendant public fuel stops will disappear within a few years.
