Statistical Simulation of Conductor Lay and AC Losses in Multi-Strand Stator Windings

The multi-strand winding configurations adopted in high-speed electrical machines are susceptible to increased AC losses as a result of proximity effects. Due to the characteristics of the insert winding process, variability can arise in the conductor lay and consequently, the AC losses of as-manufactured windings. Current finite element analysis practices cannot account for this variability resulting in under- or over-conservative AC loss estimates. This paper presents the development of a statistical simulation methodology that can represent the variability in conductor lay and AC losses of a distributed winding. Initial calibration of the methodology is achieved following statistical characterization of experimental AC loss measurements from a batch of industrial machines. The initial calibration of the methodology highlighted that only a limited amount of inter-bundle strand mixing is to be expected in as-manufactured windings, resulting in reduced variability in the expected AC losses compared to other statistical estimation approaches.