A Bipolar Coil Arrangement Method–Based Anti-Misalignment Coil Positioning for Wireless EV Charging Systems

Abstract

The paper proposes a bipolar coil arrangement method (BCAM) to identify a new anti-misalignment positioning of overlapping (OV) coils in a bipolar pad (BP) for achieving high-power transmission in a wireless electric vehicle (EV) charging system. Six different magnetic couplers with identical geometric dimensions, such as circular pad (CP), rectangular pad (RP), double-D pad (DDP), DD quadrature pad (DDQP), BP, and four-coil pad, are compared to identify a better performance charging pad. The performance evaluation for all charging pads is done by considering a vertical airgap (ΔZ) of 60–100 mm between the transmitter and receiver with and without ferrite (Fe) core and aluminum (Al) shield using ANSYS Maxwell software. In addition, the lateral misalignment (LTM) distance (ΔY) of 40–60 mm is also examined in all charging pads. The measurable quantities, such as coupling coefficient (k), the magnetic field strength (B), and mutual inductance (M), are evaluated for the above-mentioned charging pads with different misalignment conditions. The proposed coil arrangement in the BP provides better mutual inductance by facilitating omnidirectional flux distribution with ΔY of −60 to 60 mm. It also achieved the maximum DC–DC efficiency of 94.5% at ΔZ of 100 mm between charging pads by incorporating the inductor–capacitor–capacitor-series (LCC-S) compensation circuit for a 4.75 kW inductive power transfer (IPT) charging system. Finally, a small-scale laboratory-based prototype is designed for all charging pads to verify the feasibility of the proposed method. Both simulation and experimental validation ensure the improvement of DC–DC efficiency irrespective of LTMs of the proposed inward OV BP coil position.