Enhancing Resilience to Axial Misalignment in Wireless Power Transfer Systems for Internet of Things Devices

This paper presents a new effective Magnetically Coupled Resonant Wireless Power Transfer (MCR-WPT) system featuring dual transmitting coils (Tx), which can be applied to charge battery-powered Internet of Things (IoT) devices. The key to this design is to use a conventional Wilkinson Power Divider (WPD) to energize the Tx coils, establishing a coherent magnetic flux path and power transmission to the receiver (Rx) using a single input power source. The system’s operating frequency between 400 and 450 MHz can be adjusted in scale to target precise frequencies suitable for particular applications. In particular, the proposed design achieves high feasibility and flexibility of the controllable distance independently of the Rx position, which is placed between the Tx coils. As a result, the proposed system can provide an optimized resilience to axial misalignment, achieving higher Power Transfer Efficiency (PTE), when compared to a single Tx topology, where coupling effects diminish significantly when the distance between the Tx and Rx exceeds half the wavelength (λ/2).The corresponding analysis, simulation, and experimentation are carried out to prove the validity of the proposed WPT in comparison to a single transmitter configuration, including a critical comparison to a case with one non-functional Tx (Config. 2) to validate system robustness, particularly in scenarios involving unexpected degrees of axial misalignment.