Influence of the Preformed Coil Design on the Thermal Behavior of Electric Traction Machines

Abstract

Preformed coils are used in electrical machines to improve the copper slot fill factor. A higher utilization of the machine can be realized. The improvement is a result of both, low copper losses due to the increased slot fill factor and an improved heat transition out of the slot. In this study, the influence of these two aspects on the operational improvement of the machine is studied. Detailed simulation models allow a separation of the two effects. A preform wound winding in comparison to a round wire winding is studied. Full machine prototypes as well as motorettes of the two designs are built up. Thermal finite element models of the stator slot are developed and parameterized with the help of motorette microsections. The resulting thermal lumped parameter model is enlarged to represent the entire electric machine. Electromagnetic finite element models for loss calculation and the thermal lumped parameter models are parameterized using test bench measurements. The developed models show very good agreement in comparison to the test bench evaluation. The study indicates that both, the improvements in the heat transition path and the advantages of the reduced losses in the slot contribute to the improved operational range in dependency of the studied operational point.

Comparative Analysis of Electric Traction System with PI Controller and PSO Optimization Algorithm

“…The results of modelling for an electrically powered drive of a two-axle bogie having axial support and 630 kW asynchronously motor in fairly constant and start-up modes with several choices for organising circuits reentrances are shown. (Groschup et al, 2021) In synchronous generators, prefabricated coils are used to increase the copper slot fill factor. It is possible to improve the computer's efficiency.…”

Torque Ripple Minimizing of Uniform Slot Machines with Delta Rotor via Subdomain Analysis

“…As an alternative, open-slot structures are gradually adopted in the stator design for easy coil insertion from the inner air-gap side. In such a machine, preformed coils are used, so that the welding points are minimized [3].…”

Design and Application of Electrical Machines

“…In the article by Groschup et al [11], the influence of a preformed coil design on the thermal behavior of electric machines is discussed. Preformed coils are used in electrical machines to improve the copper slot fill factor.…”