Iron Loss Analysis of Stator Claw-Pole Electric-Excitation Field-Modulation Machine Considering Three-Dimensional Flux Density Distribution

Abstract

By incorporating the advantages of magnetic gearing effect and claw pole structure, a new type of claw-pole electric-excitation field-modulation (CPEEFM) machine has been developed, which has potential direct-drive application prospects due to its flexible field regulation ability and high rotor reliability. However, the axial asymmetry and the flux distribution complexity make it difficult to analytically calculate the iron loss. The purpose of this paper is to propose an improved iron loss calculation model for this CPEEFM machine, in which the iron loss coefficients are corrected accordingly by introducing the three-dimensional (3-D) flux density distortion rate to fully consider the influence of axial flux distribution in addition to the radial and tangential flux distributions. Taking a 24-slot/14-pole CPEEFM machine as an example, its iron loss characteristics under different operation conditions are calculated by the proposed model and compared with the traditional Bertotti model and the 3-D finite element analysis (FEA) implemented by JMAG software based on Fast Fourier Transform (FFT) model, which shows an acceptable consistency and improved accuracy. Furthermore, a prototype is finally fabricated and the experimental testing is carried out to verify the validity of the proposed iron loss analysis model.