Winding Losses in High-Speed Machines using Form-Wound Windings.

摘要

Understanding the ac loss phenomena in form-wound windings is critical for achieving high efficiency in ac machines that employ this type of winding. Accurate calculation of these losses using finite element (FE) analysis typically requires a fine mesh size in the conductors and small time steps, requiring considerable computational resources to accomplish.;This research program presents the development of a closed-form 2D analytical model that is capable of calculating the ac losses in form-wound windings with promising accuracy and short computation times. This model is valuable for carrying out rapid assessments of the ac losses in machines for a wide range of operating conditions, making it practical to evaluate large numbers of candidate designs.;Significant attention is devoted to exploring alternative approaches for reducing these ac losses that are influenced by many winding design factors including the conductor locations and thicknesses, number of conductors per slot, and phase arrangement.;In addition, experimental tests have been carried out using three identical stators with form-wound, "pseudo" Litz and true Litz windings, all configured with the same winding function. The availability of these stators makes it possible to experimentally segregate the winding losses, explore winding losses under different operating conditions, and, finally, build confidence in the proposed model.;The results of this investigation highlight the advantages of form-wound windings for low-frequency operation while also clearly demonstrating the risks that they present for unacceptably high ac losses at elevated frequencies. This work also demonstrates that careful attention to the design details of form-wound windings can lead to promising reductions of the ac winding losses under demanding operating conditions associated with high-speed operation.