Optimal Design of a Highly Integrated Brushless Rotor Power Supply for Electrically-Excited Generators in Vehicle-Related Applications

As part of the ongoing NGC-project (Next Generation Car) related to the research of new technologies for future road vehicles at the DLR, this paper is dedicated to the substitution of slip rings through an inductive power transfer system for field winding supply in wound rotor synchronous generators. Through function integrated lightweight design, due to the attachment of the rotary transformer and the co-rotating rectifier on an existing fan and the usage of standardized components for the rotational transformer, a volumetric optimized mounting as well as cost-effective system can be realized. The design of the system, regarding an optimal integration into the constraint space includes a variety of different challenges, which are subject of this work. For design purpose, an analytical model of the inductive link as well as the compensation circuitry is presented. Thereafter, a model for the rough estimation of the thermal behavior of the system inside the cooling environment was set up. A subsequent multi-criteria optimization procedure has been applied and the solution was used for a prototypical implementation of the brushless rotor supply into a given generator.