Experimental Evaluation of Layered DD Coil Structure in a Wireless Power Transfer System

Abstract

The transfer efficiency of a wireless power transfer system (WPT) is a critical and desired property for faster dynamic charging of electric vehicles, portable electronics, and battery powered medical devices. Mutual and self-inductance are two parameters that influence performance of the coil. To achieve an increase in inductance, coils are wound with more turns, therefore, making them bigger and not being able to fit into a fixed area. In this article, we have implemented a novel layered double D (LDD) coil with configuration that is optimized to create maximum constructive flux linkage between the transmitting and receiving coils. While also increasing the effective area of its parent double D (DD) coil, LDD still maintains the same lateral area. The inductances of both LDD and DD coil were measured alongside each other. LDD gave a significant increase in inductance comparison to the DD coil. Ferrite and aluminum shielding material are introduced to the coils to determine the effect on inductance. The coils had a more consistent performance when ferrite was used as a shield. By evaluating the WPT performance of various coil configurations, it was determined that the LDD coil with ferrite shield gave the best performance, making them very suitable for next generation WPT applications.