Design and analysis of a three-phase rotary transformer for doubly fed induction generators

This paper presents the design and analysis of a novel three-phase rotary transformer that can be used to replace the brushes and slip rings of the doubly fed induction generators (DFIG). Design aspects of the transformer cores are investigated to ensure easy manufacturing and a relatively constant reluctance while the secondary of the transformer is rotating. Guidelines for the air-gap, stator and rotor cores and the excitation currents are derived to ensure a balanced three-phase magnetic flux in the transformer core. Validation simulation has been provided with Matlab/Simulink simulation.