A comprehensive overview of inductive pad in electric vehicles stationary charging

Inductive charging is a technology that allows an electric vehicle (EV) to be charged without physical connections. It offers several advantages over conductive charging, in terms of automation, safety in harsh environments, reliability during environmental disasters, and flexibility. However, inductive charger experiences numerous challenges, such as complexity in design, sensitivity to misalignments, safety concerns, and high cost. Most of these challenges are associated with the transmitter and receiver coils. The literature includes plentiful studies that proposed and demonstrated different designs and structures for these coils, considering different magnetic materials, wires, and shields. There is a special need to report the findings of these studies in a single document that provides a comprehensive reference for researchers, and engineers. Therefore, this paper presents a comprehensive overview that focuses on the structures of transmitter and receiver pads. Different types of windings, (such as litz, magneto-plate, magneto-coated, tubular copper, REBCO, and Cu-clad-Al), magnetic materials (such as ferrite, nanoparticle, magnetizable concrete, and flexible core), and shielding (such as passive, active, and reactive) are summarized, explored and compared. In addition, different pad structures, such as circular, rectangular, double-D, double-D quadrature, bipolar, tri-polar, multiple-coil homogeneous, quadrupole, crossed double-D, quad-D quadrature (QDQ), and poly-phase are presented, and compared, in terms of performance, considering transmission distance, leakage flux, interoperability, tolerance to misalignment, magnetic flux, and shielding impact. Also, the paper presents the current-state-of-the-art of the developed inductive charger prototypes, commercial products available in the market, and international standards, either released or under preparation, associated with this technology.