2018-04-11 | Editor:et_editor 567 pageviews

Scientists' Dream: Charging EVs on the Freeway while on the Move

Electric vehicles (EV) might be able to be charged wirelessly while being driven on highways one day. Without excessive batteries, EVs can be driven for hundreds of miles or even thousands of miles. The idea still sounds like science fiction, but some engineers are trying to turn it into a reality.

Currently, most electric vehicles can travel 100 to 250 miles on a full charge (equivalent to 160~400 kilometers.) The sum of each vehicle's battery power range will depend on the auto model. In the entire United States, auto charging poles are still not enough. When a driver drives an EV to travel long distance, it presents a huge challenge.

The charging issue above might get resolved in two ways: using higher capacity batteries or wireless electricity transmission technologies. In the past two years, Khurram Afridi, an assistant professor from the Department of Electrical, Computer and Energy Engineering at University of Colorado Boulder, has been working with other engineers to research and develop methods to transfer electricity through electric fields at ultra-high frequencies.

Perhaps one day, this technology will not be limited to small consumer electronics segments, and will start to provide energy for larger products such as automobiles. 

The concept of wireless power transmission has fascinated scientists for many years. For example, Nikola Tesla, a genius inventor with many revolutionary inventions in the field of electromagnetic fields, had publicly performed the results of long-distance energy transmission. Tesla had a number of related patents and theoretical research works in electromagnetism. They are the cornerstones of modern wireless communication and radio.

He believed that he could transmit electricity through the air. Unfortunately, he wasn't able to win legal suits about his patents and lost most of them. Then his lack of funding led to unfinished research projects.

Nowadays, some small consumer electronics products are equipped with wireless power transmission technology. However, high-frequency technology that transmits a large amount of power has not yet been successfully developed.

In addition, charging cars through the air that run at high speeds is much harder. Another difficulty is the amount of high power electricity. For a smartphone to be charged wirelessly, it only needs 5W power. A laptop might require 100W power. In comparison, a vehicle that is moving will require some kW power.

The majority of wireless power charging technologies transfer energy via magnetic fields that travel in a circulating way. However, this method requires fragile ferrite core to make the fields and the energy directed. In other words, its costs are very high. Therefore, Khurram Afridi is considering electric fields that can significantly reduce costs to transfer energy.

Khurram Afridi's idea is to prepare one lane specific for wireless charging on freeways. When an EV that needs charging is moving on that lane, electric energy can transmit via the tiny capacitance between the road and the EV.

Of course, how big the capacitance is will determine whether to transfer enough energy that an EV needs. Thus, the team that is led by Khurram Afridi proposed a solution: increase the electric field's frequency. In his lab, the team was able to transmit kilo watt power at a frequency of trillions Hz. The research team is working hard to develop a prototype, and use the technology for real-world applications.

A freeway that can charge for EV might sound far-fetched. However, as a scientist, Khurram Afridi is optimistic about the future.

(Image credit: University of Colorado Boulder)

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