Design of Shaped Electric Machine Windings to Reduce Ohmic Losses

This work focuses on ohmic loss analysis of permanent magnet synchronous machines with fractional-slot concentrated windings. A trend is followed from published research, where coils are produced with each turn having a distinct shape, enabled by unconventional winding manufacturing technology. The physical principles of power loss within stator windings are described, as it is the foundation to then analyze several shaped coils. These are studied using finite element analysis on two surface permanent magnet synchronous machines, having single and double-layer windings and both open and semi-closed slots. A trade-off is observed between the DC and AC loss for different slot filling factors as the frequency ranges. It is demonstrated how a one-dimensional model of conductors in a slot can be setup as an optimization problem that yields an improved solution for the individual conductor heights. In addition, a FEA-based algorithm is used to shape individual conductors of a coil in the active-winding to avoid regions within the slots that would be sources of high power loss. Overall, it is found that for higher filling factors, the combination of both shaping methods produced the best results on both machines.