Design and Analysis of an Omnidirectional Dual-Band Wireless Power Transfer System

The wireless power transfer system (WPT) is becoming increasingly important for smart home automation, in which an array of wireless sensors is used to monitor and manage smart devices and furniture. Charging the sensors, which may require different frequencies, at any position in the home is a challenge. In this article, a dual-band omnidirectional 3-D WPT system is introduced for the sensors in a smart home. The power transmitted by the transmitter can be received by any receivers operating at 13.56 and 27.12 MHz located at any position. The dual-band 3-D square and circular transmitters are designed and demonstrated. In particular, an equivalent circuit model of the proposed system is derived and numerically analyzed. In addition, the efficiency of the dual-band 3-D WPT system is evaluated based on the receiving angle through simulation and measurement. At a 16 cm distance, the system can achieve efficiencies of 61.6% and 65.4% (57.15% and 61.2%) for rotating 360° at 13.56 and 27.12 MHz without a null value in the square (circular) system. Furthermore, the effect of the angular misalignment of the receiver on efficiency is also analyzed. Finally, the performance of the WPT system in a concrete structure is validated for practical scenarios.