Inductive power transmission for untethered micro-robots

A new concept for inductive power transmission is proposed to transmit constant power over a large area of interest. This concept includes a specially designed winding group at the power transmitting side, which is similar to the windings in a linear motor. The winding group generates a traveling magnetic field over the complete working area. This magnetic field causes an alternating magnetic flux through a receiving coil that is located in this magnetic field and therefore induces an alternating voltage in the coil. The realized prototype transmitted maximum 330 mW DC power at the operating voltage of 3.3 V to the power receiver, which has the dimension of 11.5 mm/spl times/11.5 mm/spl times/4.0 mm, throughout a working area of 180 mm/spl times/220 mm. Under different loads the output DC voltage of the power receiver varied from 2.6 to 5.1 V throughout the whole working area. A possible application of this method is powering of untethered micro-robots.