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    Wireless charging: A wide-bandgap sweet spot?

    Wireless power transfer eliminates worries over compatible connectivity

    By Alix Paultre | June 28, 2017

    wireless chargingExcept for those closeted away in secure labs, working on top-secret projects, electronics engineers (EEs) know by now that wide-bandgap semiconductors outperform silicon devices in just about every way. But, figuring out what actual performance benefits might accrue to a specific application is still something of a mystery. A look at the challenging world of wireless charging might illustrate how next-generation solutions can deliver performance benefits unmatchable in silicon.

    Wireless charging has become a rapidly-growing application space because of the explosion in portable electronics – everything from the smartphone to the electric vehicle needs to be charged periodically.

    But the problem with charging is compatibility — ensuring that there is a compatible charging system at the place you need to recharge your device. The obvious appeal of wireless transfer of power is that it eliminates the need to worry about cables and connectors, both in terms of connector compatibility and physical action to connect the device to the charger. In the consumer space, there are two standards organizations, the Wireless Power Consortium, which has developed the Qi standard, and the AirFuel Alliance. Both systems create tightly-coupled power transfer connections useful at distances up to several centimeters.

    By using silicon carbide (SiC) devices, the efficiency of the wireless charging system can be increased greatly, leveraging the low switching losses of SiC transistors while operating at switching frequencies of 100 kHz or higher. This also reduces the physical size of the system making it more compact and much lighter compared to conventional devices. As Dr. Peter Wawer, Division President Industrial Power Control from Infineon points out, “Silicon carbide has reached a tipping point. Our new 1200 V SiC MOSFETs have been optimized to combine high reliability with performance. They show dynamic losses which are an order of magnitude lower than 1200 V silicon (Si) IGBTs.”

    Gallium nitride (GaN) is also well suited for advanced wireless charging systems due to its high switching capability, enabling even more of a reduction in the system solution’s size and weight while also increasing performance. At the recent PCIM show in Nuremberg several companies were demonstrating functionality at a distance — wireless charging systems for drones — and wireless power development kits as design aids.

    “Charging our phones is an impressive thing, but really being able to project power and get rid of cords is where the big gain is. Dangerous environments, underwater environments, or even across a moving interface like a car door can now be served by wireless power systems” according to Alex Lidow, CEO and Founder of Efficient Power Conversion. “The big thing where I think GaN is underestimated is in its ability to integrate. With silicon, integrating multiple power components is really not practical, but in GaN it’s simple. When you integrate two power devices, you not only get more power, you get a significant reduction in space as well.”