Examenspresentation av Adarsh Bandi och Nagendra Gouthamas

Conducted at Ericsson, supervised by Fredrik Larsson

Opponents:
Kishore Balachandar and Janarthanan Veerasamy
Subramanian Ganesh and Harsh Srivastava

Abstract
In this thesis, we developed a wireless power transfer system for a confined space (15cm x 15cm x 15cm) using a series-connected transmitter (Tx) coil, generating an evenly distributed electromagnetic field. Studying a conventional system from Wurth Electronics, we examined coil geometry, alignment, and parameters affecting efficiency. Various Rx coil geometries (concentric, solenoid, and center-tapped circular) were tested, with solenoid proving stable under misalignment. Center-tapped circular coils improved range but required more turns, reducing efficiency.

For the proposed system, three transmitter coils were investigated: concentric, 2-series connected concentric, and 8-series connected concentric. The concentric coil with a large diameter exhibited high power transfer and range, but efficiency dropped by 28% with a solenoid receiver. Adapting to a 2-series connected coil enhanced efficiency under misalignment, achieving 10W at 48% efficiency. Extending to an 8-series connected coil improved coupling and efficiency, particularly under misalignment, making it suitable for the proposed system. The selected configuration, an 8-series connected concentric coil as Tx and a solenoid as Rx, achieved approximately 80% efficiency when perfectly aligned, and a more than 60% improvement under misalignment compared to the conventional system. The success lies in distributing coil turns into smaller areas and connecting them in series, improving magnetic field distribution. This configuration serves as the optimal choice for the proposed wireless power system within the confined space.

Welcome!

Nagendra, Adarsh and Torbjörn