Experimental comparison between Wound Rotor and permanent magnet synchronous machine for Integrated Starter Generator applications

Various types of electric machines can be considered for an application to Integrated Starter Generator (ISG) in automotive applications. Nevertheless, high constraints impose optimal design and control to satisfy to the specification book. Due to the absence of permanent magnets on the rotor and one supplementary control variable (field current), Wound Rotor Synchronous Machine (WRSM) may allow a higher temperature and a higher power factor operations. The paper proposes to compare a WRSM and an Internal Permanent Magnet (IPM) synchronous machine based on the same specification book, designed and controlled with the same optimal approach. These two machines have already been previously and individually described and the aim of this paper is to compare the performances on the basis of prototypes with a special attention to the generator mode. The results show that the WRSM has to be considered as a challenger for automotive applications.