A Comparative Study for Various Coil Geometries in Electric Vehicle Wireless Charging System.

A Master of Science thesis in Electrical Engineering by Hanin Hassan Kabalan entitled, “A Comparative Study for Various Coil Geometries in Electric Vehicle Wireless Charging System.”, submitted in November 2020. Thesis advisors are Dr. Mohamed Hassan and Dr. Ahmed Osman-Ahmed. Soft copy is available (Thesis, Completion Certificate, Approval Signatures, and AUS Archives Consent Form).

Abstract

Inductive coupling wireless power transfer technology is gaining interest in recent years, especially in the field of wireless charging. Range limitations and charging of electric vehicles are major concerns in the modern intelligent transportation systems. A systematic approach to design the inductive link power pads is presented in detail and the Society of Automotive Engineers (SAE) recommended practice J2954 is followed for designing the physical dimension of these power pads. In this thesis, a comparative study for the design of different coil geometries considered for EV’s wireless charging systems is carried out. In particular, a comparative performance analysis is conducted for rectangular, Double-D (DD), Double-D Quadrature (DDQ), and Bipolar (BP) power pads. This study also aims at showing how design aspects, height and vertical displacement affect the coupling behavior and misalignment tolerance while investigating the effect of the different parameters on the magnetic null phenomenon. Based on the simulation results, the geometries in which DD and DDQ coils are considered for primary and secondary coils respectively provide the highest coupling factor and the highest inductive link efficiency at various alignment conditions over a range of horizontal displacement from -800 mm to +800 mm lateral misalignment, while having the minimum charging pads weight, when compared to DD coils. A commercial electromagnetic simulation software called (ANSYS Maxwell) was adopted to simulate different coil structures and evaluate the performance of the inductive link. It is concluded that turn-to-turn spacing has the most dominant effect on the coupling performance at a fixed wire diameter. The power pad combinations such as DD_DD, and DD_DDQ are considered the best combinations that gives the best coupling performance for misalignment conditions. Rectangular power pad combined with non-polarized geometries is the proper geometry combination for static charging in perfect alignment conditions. The conducted analysis reveals that the existence of ferrite core is necessary to enhance the inductive link overall performance.