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The paper focuses on three-dimensional (3D) spatial wireless power transfer (WPT) and the challenges of improving the isolation between coils in a multiple-coil system. We analyze the mutual inductance between coils to derive an isolation method and propose a 3D overlapping multiple-coil system with high isolation for spatial WPT systems. Through performance verification, the proposed coils are verified to achieve approximately -20.1 dB isolation and an average power transfer efficiency of approximately 61.5%, even in the presence of angular or lateral misalignments of the receiving coil. This represents an improvement of approximately 41.7% over conventional multiple-coil systems. Therefore, it can be considered a viable solution to address the limitations of degraded power transfer efficiency in WPT systems designed for spatial freedom. [ABSTRACT FROM AUTHOR]

Maximum efficiency tracking (MET) with multiple concurrently-activated transmitters (TXs) has not yet been investigated thoroughly. This paper proposes a fast real-time estimation of coupling coefficients and load resistance for multiple concurrently-activated TXs and a moving RX. This is the first paper that demonstrates iteration-less, fast, communication-less MET with power regulation when the RX is moving across multiple activated TX array. The controller senses only the voltage magnitude of TX coil-capacitor resonator, and the input DC voltage and DC current of inverter. Once the parameters are estimated, the controller sets the converters to maximum efficiency point immediately. The benefits of proposed method are that it does not require a communication channel, extra circuit components for MET, time-consuming iterations and computations, and periodic interruption of power flow due to load disconnection or initialization, all of which were limitations in typical methods. Experimental results show that the proposed method provides a fast response (3.8ms) for an RX moving at 6.84 km/h across multiple TXs.

In recent years, optical camera communication (OCC) has garnered attention as a research focus. OCC uses optical light to transmit data by scattering the light in various directions. Although this can be advantageous with multiple transmitter scenarios, there are situations in which only a single transmitter is permitted to communicate. Therefore, this method is proposed to fulfill the latter requirement using 2D object size to calculate the proximity of the objects through an AI object detection model. This approach enables prioritization among transmitters based on the transmitter proximity to the receiver for communication, facilitating alternating communication with multiple transmitters. The image processing employed when receiving the signals from transmitters enables communication to be performed without the need to modify the camera parameters. During the implementation, the distance between the transmitter and receiver varied between 1.0 and 5.0 m, and the system demonstrated a maximum data rate of 3.945 kbps with a minimum BER of 4.2 × 10 − 3 . Additionally, the system achieved high accuracy from the refined YOLOv8 detection algorithm, reaching 0.98 mAP at a 0.50 IoU. [ABSTRACT FROM AUTHOR]

Multiple-input multiple-output (MIMO) wireless power transfer (WPT) technology which employs multiple transmitter (TX) coils to simultaneously couple power to the receiver (RX) coil has proved to be an effective technique to enhance power transfer efficiency (PTE). Conventional MIMO-WPT systems rely on the phase-calculation method based on the phased-array beam steering concept to constructively combine the magnetic fields induced by the multiple TX coils at the RX coil. However, increasing the number and distance of the TX coils in an attempt to enhance the PTE tends to deteriorate the received signal at the RX coil. In this paper, a phase-calculation method is presented that enhances the PTE of the MIMO-WPT system. The proposed phase-calculation method considers the coupling between the coils and applies the phase and amplitude to calculate the coil control data. From the experimental results, the transfer efficiency is enhanced as a result of the transmission coefficient improvement from a minimum of 2 dB to a maximum of 10 dB for the proposed method as compared to the conventional one. By implementing the proposed phase-control MIMO-WPT, high-efficiency wireless charging is realizable wherever electronic devices are located in a specific space. [ABSTRACT FROM AUTHOR]

In recent years, optical camera communication (OCC) has garnered attention as a research focus. OCC uses optical light to transmit data by scattering the light in various directions. Although this can be advantageous with multiple transmitter scenarios, there are situations in which only a single transmitter is permitted to communicate. Therefore, this method is proposed to fulfill the latter requirement using 2D object size to calculate the proximity of the objects through an AI object detection model. This approach enables prioritization among transmitters based on the transmitter proximity to the receiver for communication, facilitating alternating communication with multiple transmitters. The image processing employed when receiving the signals from transmitters enables communication to be performed without the need to modify the camera parameters. During the implementation, the distance between the transmitter and receiver varied between 1.0 and 5.0 m, and the system demonstrated a maximum data rate of 3.945 kbps with a minimum BER of 4.2×10−3. Additionally, the system achieved high accuracy from the refined YOLOv8 detection algorithm, reaching 0.98 mAP at a 0.50 IoU.

Wireless power transfer (WPT) technology has been widely introduced and developed over the past few years. Nevertheless, the basic WPT configuration using one transmitting (Tx) coil and one receiving (Rx) coil still achieves very limited performance in terms of power transfer distance. To overcome this limitation, various multi-coil WPT systems using three or more coils have been studied. Among them, a multiple-input single-output (MISO) structure can provide the Rx with advanced freedom in an extensive lateral area. However, few studies have investigated how far multi-Tx coils can increase the transfer distance. In this paper, we analyze the transfer distance and lateral coverage based on the generalized critical coupling condition and system energy efficiency according to the number of additional Tx coils in the MISO WPT system. The results demonstrate that the MISO WPT system using planarly arranged Tx coils improves by barely 1% in the optimal transfer distance, which achieves the maximum output power condition in a single-Tx WPT system. To validate our analysis, the MISO WPT system with seven Tx coils and seven LCC inverters was implemented and its performance was assessed. The measured results agreed well with the theoretically calculated results.

A demand-customized selective wireless power transfer system is proposed in this article. Multiple receivers can be recognized based on their positions and the magnetic field in the powering area can be controlled and regulated accordingly. For authorized receivers, the system can simultaneously deliver power to meet different output requirements for different electrical appliances, while for unauthorized ones, they can be shut down independently for energy security, even when they are also in the powering area. Compared to the traditional calculation models for multi-input multi-output systems, the proposed current control algorithm uses a piecewise optimization procedure to simplify the iteration and improve control flexibility. Hybrid-frequency pacing is adopted as the control strategy to further reduce the output fluctuation and raise the system efficiency. An experimental prototype with a 3 × 3 transmitter matrix is established. The system can successfully power two receivers with the same sizes for four different power requirement scenarios, which validates the selectivity and the controllability of the proposed system. [ABSTRACT FROM AUTHOR]

In multi-input wireless power transfer (WPT) systems, it is plagued to create a destructive interference between the multiple transmitters to result in a relatively low voltage delivered to the receiving coil and load, due to the phase differences of the received voltages from different transmitters. In this regard, it is essential to synchronize the phases of the received voltages of the receiving coil from different transmitters. However, the existing offline synchronization methodologies rely heavily on an analytical form solution of the received voltage in a receiver. In most engineering application scenarios, such close-form solution is almost impossible. Moreover, the close form solution, even if possible, will vary with the operating conditions and environments. To eliminate these deficiencies of existing synchronization methodologies, an online synchronization methodology is proposed for a multi-input WPT system. In the proposed methodology, the received voltages from different transmitters are determined from a series of online voltage samplings under different offset phases, and a synchronization strategy is then proposed and implemented. A multi-input WPT prototype is developed to test the feasibility of the proposed synchronization methodology. The experimental results have demonstrated that the received voltage is significantly enhanced by applying the proposed online phase synchronization methodology. [ABSTRACT FROM AUTHOR]

Multiple-input multiple-output (MIMO) wireless power transfer (WPT) technology which employs multiple transmitter (TX) coils to simultaneously couple power to the receiver (RX) coil has proved to be an effective technique to enhance power transfer efficiency (PTE). Conventional MIMO-WPT systems rely on the phase-calculation method based on the phased-array beam steering concept to constructively combine the magnetic fields induced by the multiple TX coils at the RX coil. However, increasing the number and distance of the TX coils in an attempt to enhance the PTE tends to deteriorate the received signal at the RX coil. In this paper, a phase-calculation method is presented that enhances the PTE of the MIMO-WPT system. The proposed phase-calculation method considers the coupling between the coils and applies the phase and amplitude to calculate the coil control data. From the experimental results, the transfer efficiency is enhanced as a result of the transmission coefficient improvement from a minimum of 2 dB to a maximum of 10 dB for the proposed method as compared to the conventional one. By implementing the proposed phase-control MIMO-WPT, high-efficiency wireless charging is realizable wherever electronic devices are located in a specific space.

With the widely applying of inductive power transfer (IPT) sharing platforms in public, the security issue imposed by the leaked electromagnetic field (EMF) of standby transmitters (Txs) becomes one of the concerned topics. Multiple Txs may be an effective scheme to suppress the leaked EMF for which each Tx can be controlled independently. For the traditional technologies, multiple inverters, sensors, or wireless communication links are needed to achieve load detection and independent control, which increases the cost and reduces the system's reliability. This work presents an IPT system with dual secondary loops, which only needs a single inverter and can automatically control the Txs by its circuitry reflective property. The system can enhance the transmitting current when Rx couples with Tx and weaken that when Rx does not couple with Tx. Furthermore, a capacitor array is added in the secondary circuit to adapt different primary reactances by utilizing a simple switching-control method. Finally, a prototype that can transfer 112 W with a dc–dc efficiency of 91.79% is built to validate the feasibility of the proposed system. The experimental results show that the current in coupled Txs is three times higher than that in uncoupled Txs as per the theoretical analysis. [ABSTRACT FROM AUTHOR]