To develop a fault tolerant machine with the least redundant phases, the inductance model and a nonlinear radial air gap flux density model of a new four-phase doubly salient electromagnetic generator (DSEG) is presented and verified by the finite element analysis (FEA) and experiments result in this paper. With the proposed formulas, a new four-phase 24-slot 18-pole DSEG without cogging torque was designed. It can be concluded from the models that the magnetic circuit model is very helpful to find the most critical structural parameters of the machine. The FEA and experiments of the DSEG show that the proposed models can calculate the radial air gap flux density and the winding inductances.

Keywords: Doubly salient electromagnetic generator, Fault tolerant, Four-phase, Electromagnetic characteristic, Inductance model