Design, Manufacture, and Test of a Rotary Transformer for Contactless Power Transfer System

In traditional applications such as machine field excitation, where power transfer from stationary to rotary side is needed, contact slip rings are often adopted. However, this kind of slip ring is easy to wear and needs frequent maintenance. In a contactless power transfer system, mechanical slip rings can be removed which will largely increase the system reliability. In this article, a contactless power transfer device using wireless power transfer (WPT) is designed. Its performances are simulated by finite-element method. To increase the system power rate and efficiency, the device is operated under high frequency. Thus, high-frequency ferromagnetic materials and Litz wires are used. Moreover, compensation circuits are added to improve the coupling between the primary and secondary sides. At last, a prototype is built and tested. From the experimental results, the functions and performances of the device are well verified.