Wireless charging pad based on travelling magnetic field for portable consumer electronics

Wireless charging platforms are becoming popular due to the elimination of electrical connectors. However, generating a uniform magnetic field over the charging pad is technically a challenging task, and normally it ends up using a charging pad with multi-layers and coils. This paper proposes a novel wireless charging pad based on travelling magnetic field. The moving feature of the proposed magnetic field simplifies the pad to a simple single-layer design, while giving the free positioning of the receiver coil above the pad. The basic principle of operation of the new design is presented in details. A 3D finite element model is developed to study the magnetic coupling property, particularly the uniformity of the magnetic field distribution above the pad. A complete practical set-up is constructed to evaluate the system performance. The simulation results revealed a reasonably uniform magnetic field distribution above the charging pad without any `dead areas´ with zero magnetic field. The practical results has demonstrated that the average uncompensated power (Su=Isc.Voc) transferred to the receiver coil is about 1.3 VA, providing a maximum power transfer potential of 6.5W for charging consumer electronic devices such as mobile phones if the pickup circuit is tuned at a quality factor Q of 5.