Clarification on How Wireless Charging Works

[pcvrx560]

As far as I know, they use two coils and rely on a changing electromagnetic field to transfer electric current. So would wireless charging not work for DC current since a constant voltage would create an unchanging electromagnetic field and therefore unable to induce a current in the other coil?

 

[Phrak]

It's like a transformer, in principle. A changing current is required.

 

[AJ Bentley]

But it's perfectly simple to convert DC to AC, transfer wirelessly, then convert it back.

In fact it's often done by converting to DC, then to AC again at a more convenient frequency than mains cycles - do the wireless transfer, then rectify back to dc to charge a battery.