A High-Torque Magnetless Axial-Flux Doubly Salient Machine for In-Wheel Direct Drive Applications

In this paper, the concept of dc-field excitation is newly incorporated into the axial-flux doubly salient (AF-DS) machine, leading to create the new magnetless AF-DSDC machine. With the external field excitation, the proposed machine not only can enjoy its improved torque density, but also the flux-weakening capability for the wide-speed range operation. With these characteristics, the AF-DSDC is favorable for the in-wheel direct drive application. In particular, the proposed machine is designed and compared based on the requirement of a typical passenger electric vehicle. To have a better illustration, a radial-flux DSDC machine is also designed under the fair environment. The corresponding performances of both machines are analyzed by using the 2-D and 3-D finite element method.