Dual-band wireless power transfer with reactance steering network and reconfigurable receivers

Wireless power transfer (WPT) via near-field magnetic coupling is an enabling technology for many applications. A few WPT standards are under development with frequencies ranging from kilohertz (kHz) to megahertz (MHz). Operation in kHz offers a higher power rating and that in MHz offers a smaller size. This paper presents a dual-band WPT architecture with novel transmitter and receiver topologies that can achieve high performance at both 100 kHz and 13.56 MHz with low component count and decoupled power delivery at different frequencies. On the transmitter side, we introduce an enhanced push-pull Class-E topology together with a reactance steering network (RSN), which can seamlessly compensate the load impedance variation for MHz wireless power transmitters. On the receiver side, we present a reconfigurable dual-band rectifier that can achieve a power density of 300 W/in³ with low component count and low total harmonic distortion. A complete dual-band WPT system comprising an RSN-based dual-band transmitter and multiple reconfigurable receivers has been built and tested. The WPT system can simultaneously deliver a total of 30 W of power to multiple receivers (15 W maximum each) with 82.5% efficiency at 100 kHz and 74.8% efficiency at 13.56 MHz with 2.8 cm of coil distance and up to 5 cm of coil misalignment.