Transverse Flux Machines with rotary transformer concept for wide speed operations without using Permanent Magnet material

Abstract

This paper presents a new concept of Transverse Flux Machine (TFM) design that uses rotary transformers to replace the Permanent Magnet (PM) field excitation in the rotor. The rotary transformer has an inductive interface that allows for contactless transfer of energy to the field windings embedded in the rotor core. In order to achieve high magnetic coupling, a highly permeable ferrite core is selected for the transformer which is excited with high electrical frequency of 100 kHz. A field power converter is used to regulate the transformer secondary winding voltage to maintain constant DC field in the rotor. The proposed TFM has a modular structure that is free of PM, which makes it cost-effective, without sacrificing its peak torque and power when compared to a similar sized PM based TFM.