Design and analysis of interior permanent magnet machines equipped with novel semi-overlapping windings

A novel winding topology comprising semi-overlapped windings has been proposed in this study. The main advantages of such winding over conventional-distributed (overlapping) and fractional-concentrated (non-overlapping) windings are having very short-end winding lengths and significantly low magnetomotive force harmonic content, respectively. The key design rules, basic properties, and other merits and demerits of the proposed novel winding topology are justified. The key performance characteristics of the proposed winding topology are disclosed through an interior-permanent magnet (IPM) machine. The obtained electromagnetic analysis results are compared with those of other IPM machines having conventional-distributed and fractional-concentrated windings. It has been demonstrated that the proposed winding topology promises significant superiorities such as improved efficiency with substantially reduced total axial length, low eddy current losses, and low risk of irreversible magnet demagnetisation over other winding topologies. The analysis is verified by finite-element analysis results and experiments on a prototype novel semi-overlapping winding IPM machine.