Abstract
Conventional magnetically coupled resonant wireless power transfer systems are faced with resonant frequency splitting phenomena and impedance mismatch when a receiving coil is placed at misaligned position. These problems can be avoided by using uniform magnetic field distribution at receiving plane. In this paper, a novel 3D transmitting coil structure with improved uniform magnetic field distribution is proposed based on a developed optimization method. The goal is to maximize the average magnetic field strength and uniform magnetic field section of the receiving plane. Hence, figures of merit (FoM1 and FoM2) are introduced and defined as product of average magnetic field strength and length or surface along which uniform magnetic field is generated, respectively. The validity of the optimization method is verified through laboratory measurements performed on the fabricated coils driven by signal generator at operating frequency of 150 kHz. Depending on the allowed ripple value and predefined coil proportions, the proposed transmitting coil structure gives the uniform magnetic field distribution across 50% to 90% of the receiving plane.
Highlights
Numerous wireless power transfer (WPT) systems operate through nonuniform magnetic field strength distribution at receiving plane
According to the simulation results, experimental TX-coils are made out of Litz wire instead of PCB realization which is not appropriate for large receiving plane. Both computer simulation and measurement results verified that uniform magnetic field distribution at considerable surface of the receiving plane is produced by the novel 3D TX-coil structure
We focused on a two-layer 3D coil structure, due to simpler fabrication compared to a multilayer coil with respect to required precision of manufacture
Summary
Numerous wireless power transfer (WPT) systems operate through nonuniform magnetic field strength distribution at receiving plane. A novel 3D structure of TX-coil is proposed to achieve uniform magnetic field distribution at the given receiving plane (114 × 28 cm). Uniform magnetic field strength distribution at a receiving plane results in a WPT system that does not require frequency tracking and automatic impedance matching [8]. Uniform magnetic field strength distribution at a receiving plane ensures nondegraded wireless power transfer efficiency regardless of RX-coil position within receiving plane [1]. According to the simulation results, experimental TX-coils are made out of Litz wire instead of PCB realization which is not appropriate for large receiving plane Both computer simulation and measurement results verified that uniform magnetic field distribution at considerable surface of the receiving plane is produced by the novel 3D TX-coil structure. With the approximately 100 W of output power at receiving side of a WPT system, application of such TX-coil enables simultaneous wireless charging of monitors, smartphones, laptops, etc
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