Optimized Power Pads for Charging Electric Vehicles Based on a New Rectangular Spiral Shape Design

Abstract

Electric vehicles (EVs) can be charged wirelessly using inductive charging technology. This process has a number of advantages in terms of automation, safety in harsh environments, reliability in the event of natural disasters and adaptability. On the other hand, the inductive charger has many issues, including a complex design, sensitivity to misalignment, safety concerns, and a high cost. The transmitting and receiving coils are the primary causes of the cited problems. This paper presents an in-depth study of an electric vehicle charging system based on the magnetic coupling between two coils by introducing different materials to concentrate the magnetic flux and hence improving the overall efficiency of the charging system and its design. Three situations of the magnetic coupling between two identical rectangular coils as a function of both the horizontal (X axis) and vertical (Z axis) alignment are examined. In the first case, the analysis of the magnetic coupling between two copper coils separated by an air gap is presented. The results show that the magnitude of the fields decreases according to the distance between the transmitter and the receiver coils and the obtained coupling coefficient was very low with a high leakage flux which affected the performance of the charging system. In the second case, a straightforward shielding method that involves inserting a magnetic material of the ferrite type is proposed to overcome these problems. The use of ferrite magnetic shielding contributes to channeling the field lines as well as reducing leakage flux which makes the transmitted power higher. This perspective shows that simple shielding is still only a partial and insufficient solution. In the third situation, an aluminum sheet was consequently placed on the top of the ferrite to provide an adequate shielding structure. A 3D analysis of the self and mutual induction parameters separating the two coils as well as a magnetic field is also performed using the Ansys Maxwell software. The results highlight the significance of the enhanced proposed design.