Wireless charging at 500 kW with a performance of 98%, the technology that opens the door to ultra-fast stations without cables
Researchers from the Chalmers University of Technology (Sweden) have developed an induction charging technology capable of reaching 500 kW of power in direct current as well as offering an efficiency of 98%. The team behind this breakthrough says the new system will soon be presented to the industry for commercialization.
Professor Yujing Liu, who is leading the project at Chalmers’ Department of Electrical Engineering, says that in terms of performance, it is one of the most efficient wireless charging systems in its power range. The researchers have used already existing components, which explains why this technology is practically ready to reach the market.
“A key factor is that we now have access to high-power semiconductors based on silicon carbide, so-called SiC components. They allow us to use a higher voltage, a higher temperature, and a much higher switching frequency compared to classical silicon-based components.”
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“Previous systems for wireless vehicle charging have used frequencies around 20 kHz. They were bulky, and the energy transfer was not very efficient. Now we work with four times higher frequencies. So induction becomes more attractive.” The frequency of the magnetic field sets the limit on the amount of energy that can be transferred between two coils.
An ideal solution for electric buses
Another recent advance that has been able to incorporate is coils made up of twisted “copper cords”, made up of up to 10,000 copper fibers (each between 70 and 100 micrometers thick).
As a result of the efficiency we have recently attained, losses in an inductive charging system may be practically as low as those in a conductive charging system. In reality, the difference is minor, only 1% or 2% in size.
The solution developed by Chalmers is powerful enough to load buses extremely quickly without human or robotic intervention. “It can facilitate the electrification of large vehicles and therefore speed up the phasing out of, for example, diesel-powered models.” Interestingly Yujing Liu doesn’t think it will be especially useful for electric passenger cars.