Traveling magnetic field for homogeneous wireless power transmission

A novel concept for wireless power transmission using inductive coupling is proposed to transmit power homogeneously over a large working area. This concept includes a specially designed winding group on the transmitting side to generate a traveling magnetic field, which causes an alternating magnetic flux through a receiving coil that is located in this field and, therefore, induces a voltage in the coil. The prototype system provides an effective working area of 180 x 220 mm for one or more power receivers that is 4.0 mm thick and 11.5 nun in diameter. Each receiver receives a constant power of about 330 mW at 3.1 +/- 0.4 V dc operating voltage throughout the working area. A. possible application of this concept is the powering of untethered microrobots.