Two-Degree-of-Freedom WPT System Using Cylindrical-Joint Structure for Applications With Movable Parts

Abstract

A new winding structure for wireless power transfer (WPT) systems is proposed. The transmitter (Tx) and receiver (Rx) coils are wound on a semicylindrical and cylindrical structures, respectively. Thus, the Rx coil has two degree-of-freedom (2-DoF) movements. The first is linear ( ${\Delta }$ ) movement along the axial direction of the joint. The second is angular ( ${\alpha }$ ) movement around the axial direction of the joint, while transferring power. Winding methods and design procedures are discussed in detail. A prototype was built to validate the proposed idea. Experiment results have confirmed that the proposed structure achieved a constant power transfer efficiency (PTE) under linear movement. In addition, the Rx coil rotated up to 85° and maintained low variations of the efficiency, where PTE decreased by 4.61% for rotation between 0° and 85°. Moreover, the proposed WPT coils maintained a constant PTE under dynamic conditions. The proposed winding structure could be a good technique for applications that require linear and angular movements.