Eddy-Current Loss and Temperature Rise in the Form-Wound Stator Winding of an Inverter-Fed Cage Induction Motor

Temperature rise of the form-wound multi-conductor stator winding of a 1250-kW cage induction motor was analyzed. Eddy currents in the winding significantly affect the temperature rise. The eddy current was modeled using time-discretized finite-element analysis (FEA). The resistive losses in each of the bars obtained from the FEA are used as input for thermal modeling. The distance from the air gap to the topmost bar in the stator has a significant effect on the eddy-current loss as well as temperature rise in the winding. An acceptable distance for winding design was recommended. By using magnetic slot wedges the eddy-current losses can be reduced.