Effects of coil shapes on wireless power transfer via magnetic resonance coupling

Abstract

The wireless system with four coil resonators is a popular configuration for mid-range wireless power transfer (WPT) via magnetic resonance coupling. The design parameters of four coils have strong impact on efficiency, bandwidth, and transfer distance of the WPT system. In this work, a comprehensive study on effects of coil shapes is conducted. In particular, helix coils, planar spiral coils, and square helix coils are studied. It is shown that the helix coils offer the best performance (e.g. the highest efficiency, the widest bandwidth, and the longest transfer distance) under optimal load whereas the planar spiral coils exhibit the worst performance among these three types of coils. Nevertheless, the performance of the WPT system with helix coils degrades more rapidly than these with other two types of coils when the distance between the transmitting and receiving coils increases.

Keywords:

• wireless power transfer
• magnetic resonance coupling
• coil resonators
• coil shape effects
• power transfer efficiency
• power transfer distance

Funding

This work was supported in part by the National Science Foundation of China [grant number 51107089], [grant number 61331007], [grant number 61106067], and [grant number 61006080]; CAST Foundation [grant number CAST201241]; and Shenzhen Special Funds for the Development of Strategic Emerging Industries [grant number JCYJ20130401160028789].