Designing for Conductor Lay and AC Loss Variability in Multistrand Stator Windings

Vehicle electrification places significant pressures on electric machine design due to the need for increased power densities and mass production. These two requirements couple when designing multistrand stator windings, which exhibit significant ac loss variability as a result of the random nature of the conductor lay within the stator slot caused by automated insert winding. This paper presents two prediction methods for ac loss variability to be deployed at the winding design stage. The first consists of an analytical approach, whilst the second constructs a 2D finite element analysis geometry that captures conductor lay characteristics. Comparison of predictions from both approaches to experimental ac loss measurements established that the proposed models capture the experimentally observed ac loss variability characteristics and that the analytical method is suitable for early design stages whilst the finite element approach should be adopted once the winding configuration is finalised.