Form-wound stator winding for high-speed induction motors

Random-wound stator windings of high-speed induction motors (HSIM) have serious problems with eddy-current losses because their circular copper wires are randomly distributed. As a result, the differences in the total electromotive forces induced in the parallel conductors cause high additional losses in random-wound windings. Moreover, the eddy-current losses are underestimated during design stage due to difficulties of modeling eddy-current effect in the random-wound windings. A form-wound stator winding is an alternative option to reduce those losses. A roughly designed model of form-wound winding is presented based on the original random-wound stator windings of HSIM. Time-discretized finite-element analysis (FEA) is used to model losses in a 300 kW HSIM with random and form-wound stator windings. Those losses are used as the input data for the temperature rise analysis to check temperature rise constraints of the designed machine. Possibilities using form-wound windings for HSIM are evaluated from the losses and temperature rise analysis.