Novel hybrid-excited permanent magnet machine based on the flux modulation effect

Abstract

Hybrid-excited permanent magnet (PM) machines incorporate the merits of both the PM machines and the electric-excited machines, but they usually need slip rings and brushes for the electric excitation and their structures are usually quite complex. In this paper, a novel hybrid-excited PM machine is proposed. Using the flux modulation effect, the PM excitation and the electric excitation are coupled via different field harmonics. It helps the PM to get rid of the risk of irreversible demagnetization. Moreover, the dc excitation coils are accommodated in the stator so that it does not need slip ring or brush, making the machine simple and reliable. The working principle and electromagnetic performance of the machine are validated using finite element method (FEM).