Magnetically Decoupled Modular Coil Array for Dynamic Wireless Power Transfer With Magnetic Beamforming

Abstract

Dynamic wireless power transfer (DWPT) has emerged as a technology for delivering sustainable energy to mobile electric vehicles without charging cables. Magnetic beamforming is a well-known DWPT strategy for increasing power transfer efficiency (PTE) by calculating an optimal weight for focusing the magnetic fields from the transmitting (TX) coils to the desired receiving (RX) coils. However, when magnetic beamforming is applied to multi-inputs and multi-outputs (MIMO) WPT, the cross-coupling at TX and RX coils inevitably emerges, resulting in deterioration of the PTE and power factor (PF). This paper presents a magnetically decoupled modular coil array for MIMO-WPT applicable to a DWPT environment. First, we present a mathematical analysis of the influences of magnetic couplings in MIMO-WPT. Then, we derive the criteria of magnetic couplings in terms of improved PTE and PF and design a modular coil array that satisfies the derived criteria. Finally, we compare the proposed modular coil array with an existing square coil array in a DWPT environment via a 3D finite element analysis simulator. The proposed modular coil array achieves PTE improvement of up to 30 %, whereas the existing square coil array ends up to 18 %, as the number of receiving coils increases from one to five. In addition, the PF of the proposed modular coil array is close to 1.0, whereas that of the existing square coil array is attenuated up to 0.5.

Keywords

• Magnetic beamforming
• cross-coupling
• dynamic wireless power transfer (DWPT)
• modular coil array
• 3D finite element analysis (FEM)
• power transfer efficiency