A Contactless Energy Transfer System With High Misalignment Tolerance for Rotary Ultrasonic Machining

In rotary ultrasonic machining, the contact energy transfer with traditional carbon brushes and conductive slip rings not only has a short life, but also limits the increase of speed, and is gradually replaced by contactless energy transfer with loosely coupled transformer. Because there is no physical connection between the transmitting side and the receiving side of the loosely coupled transformer, the magnetic cores on both sides are easy to shift, which is one of the characteristics of contactless energy transfer. To meet the need of automatic tool change flexibility, existing achievements design a single-emission loosely coupled transformer. However, it requires high assembly accuracy of the machine tool, and small assembly error will lead to large fluctuations in the output power of the system. This article designs a symmetrical multiemission loosely coupled transformer with high misalignment tolerance, no matter which direction the secondary magnetic core is offset, the fluctuation range of the coupling coefficient is small. Because the inductance of the multiemission primary circuit as a whole changes slightly after offset, by compensating all of the primary coil inductors with a capacitor, transfer efficiency and output power fluctuation caused by misalignment can be effectively reduced, and the stability of energy transfer and the consistency of the processed workpiece can be improved.