Hybrid Magnetic Shielding Design for DD Coils in Electric Vehicle Wireless Power Transfer System

In recent years, electric vehicle wireless power transfer (WPT) technology has been widely adopted due to its ability to overcome limitations of conventional wired charging methods, such as low convenience and safety risks. However, magnetic leakage during power transmission may cause electromagnetic interference and potential health hazards. To effectively control leakage magnetic fields in WPT systems, this study investigates the magnetic field distribution around DD coils and proposes a hybrid shielding configuration. The design integrates active shielding combining passive shielding coils with passive shielding components, along with passive shielding composed of L-shaped ferrite blocks and aluminum plates, aiming to mitigate leakage fields. Using three-dimensional finite element electromagnetic simulation, the magnetic flux density in different zones, transmission efficiency, and material savings were analyzed for a 3.3 kW EV WPT system with this shielding structure. Results demonstrate that compared with traditional ferrite plates, the proposed hybrid shielding effectively reduces leakage fields above and around the DD coils while achieving 77.67% reduction in ferrite material usage, and the efficiency of the wireless power transmission system remains at a high level.