Efficient Wireless Power Transmission Systems Research Articles

High Efficiency Wireless Power Transmission System That Uses HTS Transmitting and Copper Receiving Coils With a Large Difference in Quality Factor

We developed an efficient wireless power transmission (WPT) system using a high-temperature superconductor (HTS) spiral coil with a high quality factor as the transmitting coil and a copper coil as the receiving coil. The HTS spiral coil was fabricated using double-sided HTS wire which we developed previously. The double-sided HTS wire consists of two conventional HTS coated conductor wires. The measured quality factor of the HTS spiral coil containing modified coil support was about 14 times higher than that of the copper coil. We designed the WPT system using the filter design theory. We measured the design parameters for a coupling coefficient and an external quality factor. We measured the power transmission efficiency (PTE) of the WPT in the facing direction, position misalignment, and angular misalignment. The PTE of the WPT system with the high quality factor HTS spiral coil showed significant improvements in all measurements compared to the system with copper coils.

Propagation Characterization of the Electromagnetic Wave along with the Interface between Two Lossless Dielectric Media

A Transverse Electric (TE) mode of propagation having the electric field perpendicular to the interface is considered. Two media are assumed to be lossless. Phase velocities of the waves through the two media and the interface are calculated. These velocities are found to be different from the actual phase velocities in the dielectrics. The phase velocity in one dielectric is modified by the presence of another dielectric medium. The phase velocities in the two media are greater than the phase velocity of the wave along with the interface. Also, the phase velocities in the media in contact are greater than the velocities of the wave in the two media when they are separated. The wave is found to bend away from the interface in both the media. Very low loss dielectric media are practically lossless at very low frequencies. These dielectric media may be useful for Wireless Power Transmission (WPT) system. The bending property of the electromagnetic wave away from the interface and the low loss will help one to locate the receivers away from the transmitter in the WPT system. The use of very low loss dielectric media and Very Low Frequency (VLF) transmitter are suggested for efficient WPT systems.

Metamaterial-Enhanced Magnetic Coupling: An Inductive Wireless Power Transmission System Assisted by Metamaterial-Based µ-Negative Lenses

In recent years, significant attention has been directed toward the design and optimization of inductive-coupled resonant systems for wireless power transmission (WPT). Due to emerging applications, ranging from electric vehicle charging to wirelessly powering and recharging medical implants, the need for efficient WPT systems is increasing.

A Smart Cage With Uniform Wireless Power Distribution in 3D for Enabling Long-Term Experiments With Freely Moving Animals.

This paper presents a novel experimental chamber with uniform wireless power distribution in 3D for enabling long-term biomedical experiments with small freely moving animal subjects. The implemented power transmission chamber prototype is based on arrays of parallel resonators and multicoil inductive links, to form a novel and highly efficient wireless power transmission system. The power transmitter unit includes several identical resonators enclosed in a scalable array of overlapping square coils which are connected in parallel to provide uniform power distribution along x and y. Moreover, the proposed chamber uses two arrays of primary resonators, facing each other, and connected in parallel to achieve uniform power distribution along the z axis. Each surface includes 9 overlapped coils connected in parallel and implemented into two layers of FR4 printed circuit board. The chamber features a natural power localization mechanism, which simplifies its implementation and ease its operation by avoiding the need for active detection and control mechanisms. A single power surface based on the proposed approach can provide a power transfer efficiency (PTE) of 69% and a power delivered to the load (PDL) of 120 mW, for a separation distance of 4 cm, whereas the complete chamber prototype provides a uniform PTE of 59% and a PDL of 100 mW in 3D, everywhere inside the chamber with a size of 27×27×16 cm(3).

Inner-Field Guiding Resonator for Efficient Wireless Power Transmission in Proximity Charging Condition

An inner-field guiding resonator (IFGR) is presented for efficient wireless power transmission (WPT) using resonant inductive coupling in proximity charging condition. The IFGR is inserted into a source resonator to obtain a uniform magnetic field distribution which is the important design factor of a proximity WPT system, because it makes the system simple without an adaptive matching technology. As the location of the target resonator changes, the transmission efficiencies are simulated and measured to validate uniform- and high-transmission efficiency. To optimize the WPT system using the IFGR, the design procedure is proposed. Considering the practical WPT system with ground plane, the proximity WPT system including one or two mobile devices was designed and fabricated. The average of the total efficiency at all positions on the source resonator was measured as 82.9% (one mobile device) and 87.1% (two mobile devices), respectively. These results prove that an efficient proximity WPT system can be successfully designed using the IFGR.

Wireless Power Transmission: R&D Activities Within Europe

Wireless power transmission (WPT) is an emerging technology that is gaining increased visibility in recent years. Efficient WPT circuits, systems and strategies can address a large group of applications spanning from batteryless systems, battery-free sensors, passive RF identification, near-field communications, and many others. WPT is a fundamental enabling technology of the Internet of Things concept, as well as machine-to-machine communications, since it minimizes the use of batteries and eliminates wired power connections. WPT technology brings together RF and dc circuit and system designers with different backgrounds on circuit design, novel materials and applications, and regulatory issues, forming a cross disciplinary team in order to achieve an efficient transmission of power over the air interface. This paper aims to present WPT technology in an integrated way, addressing state-of-the-art and challenges, and to discuss future R&D perspectives summarizing recent activities in Europe.