Sam writes.
“An electromagnet levitates a ring of LEDs attached to a coil. The LEDs are powered using a wireless power transfer from another coil under the electromagnet.
 Levitation is achieved using a Hall effect sensor and a proportional controller implemented on a KA7500 SMPS controller. The wireless power transfer system consists a Class E DC/AC inverter operating at 800 KHz.
 The LEDs can be rotated to give a very nice visual effect which is shown at the end of the video”