Design of a Brushless Rotor Supply for a Wound Rotor Synchronous Machine for Integrated Starter Generator

Wound rotor synchronous machines present interesting performances for integrated starter generator. Nevertheless, the lack of reliability of their gliding contacts remains their main drawback. The following paper proposes to replace the gliding contacts of such a wound rotor synchronous machine by an iron silicon axial rotary transformer operating as a contactless transmission power system. The design process is based on an accurate non-linear multidisciplinary analysis model divided into a magnetic, thermal and electrical part, optimized thanks to a sequential quadratic programming algorithm. The method is applied to a particular wound rotor synchronous machine and the electromagnetic and thermal performances are subsequently confirmed using the finite element method (FEM). The optimal result indicates that the rotary transformer is a good challenger to gliding contacts in term of compactness. Other advantages and limitations of the optimal rotary transformer are discussed.