Design of a permanent-magnet flux-modulated machine with a high torque density and high power factor

This study presents a novel approach to the design process of a permanent-magnet flux-modulated machine by simultaneously focusing on the machine major advantage and disadvantage, that is, the high torque density and low power factor. The machine can be designed with a high power factor while retaining the high torque density. To do so, they both need to be described precisely. The torque equation is improved by considering the stator-winding leakage flux. It determines the relation between the geometric parameters and the torque more accurately. The power-factor equation is derived from the electric equivalent circuit representing the simplest description of the machine. The machine geometry optimised with the design of experiments via Taguchi methods assures the best possible performance within the set limitations. It is shown that using the proposed design process makes the permanent-magnet flux-modulated machine more appropriate than the classical synchronous machine for the direct drive applications requiring a high torque density, low weight and high efficiency.