Optimized Design of Opened Quasi-Static Cavity for Omnidirectional Wireless Charging Systems

Optimizing three-dimensional (3D) omnidirectional wireless power transfer (WPT) remains a challenging goal in modern power electronics systems. While several methods, such as orthogonal coil designs and current control strategies have been explored, they still struggle with high degree of freedom charging. Compared to conventional WPT systems, the cavity resonance method offers a promising alternative. This article proposes an opened quasi-static cavity resonance (O-QSCR) structure for this application, which generates a uniform magnetic field throughout the space by driving a wide, even current along its surface. Besides, a method for rapidly evaluating the magnetic field uniformity is introduced to optimize the cavity configuration of O-QSCR based on the magnetic field distribution. Following that, the performance of the proposed O-QSCR system is analyzed using transmission theory and validated through both electromagnetic simulations and experiments. Experimental results show that the transmission efficiency stays above 46% in 95% of the space and exceeds 20% even when the receiver rotates by 60° offset. The proposed system has the capability to light up LEDs at various positions and angles, offering an innovative and practical solution for omnidirectional charging in future 3D environments.