Study on pole number and pole arc coefficients of multiphase wound-field doubly salient generators

The wound-field doubly salient generator (WFDSG) will produce a great cogging torque and a field winding back EMF if its pole number and pole arc coefficients were not well designed. In order to design a multiphase WFDSG with fault tolerance and low voltage ripple, this paper investigates the pole number and pole arc coefficients of the multiphase WFDSG. Based on the analysis of the WFDSG principle, the design requirements for WFDSG are presented. The relationship between performance parameters and topology parameters that includes the stator pole, the rotor pole and their pole arc coefficients is analyzed. The constraint rules of the machine stator pole, the rotor pole and their pole arc coefficients for multiphase doubly salient machine are given, which provide a theoretical basis for the phase redundant WFDSG. A new 12/9-pole four-phase WFDSG is proposed and designed. And its characteristics are investigated by the finite element method (FEM) simulation and the experiment on a prototype of WFDSG. Both simulation and experimental results verify that the design method and the machine structure presented in this paper are correct. © 2015 Chin. Soc. for Elec. Eng..