Patent ID: 6088905
Filing Date: 2000-07-18
Classification: H02K,Y10T

Abstract:
A method for constructing a squirrel cage rotor formed by rotor laminations having multiple circumferentially spaced slots, the rotor being for use in a dynamoelectric machine having a stator including a stator core and windings on the stator core, the method comprising the steps of:determining the number of slots S in the stator core and the number of poles P of a fundamental winding on the stator core;selecting a distance .delta./2 to inhibit the occurence of more than one saturation region associated with each rotor slot;forming a first set of rotor laminations made of highly magnetically permeable material, each rotor lamination having slots therein spaced circumferentially around its periphery and each slot including a radially inner portion and a radially outer skew portion extending radially outwardly and laterally in a first direction from the radially inner portion toward the circumference of the rotor lamination;forming a second set of rotor laminations made of highly magnetically permeable material, each rotor lamination having slots therein spaced circumferentially around its periphery and each slot including a radially inner portion and a radially outer skew portion extending radially outwardly and laterally in a second direction from the radially inner portion toward the circumference of the rotor lamination, the lateral extension of the skew portion from the radially inner portion of the slots of the second set of rotor laminations being opposite the lateral extension of the skew portions of the slots of the first set of rotor laminations;stacking the first set of rotor laminations one on top of the other with their slots substantially in registration;stacking the second set of rotor laminations one on top of the other on top of the stack of the first set of rotor laminations, the slots of the second set of rotor laminations being generally in registration, the radially inner portions of corresponding slots in the first and second set of rotor laminations generally overlying each other;the slots in the rotor laminations being shaped and arranged so that as stacked together the laterally outermost points of the skew portions of the corresponding slots in said first set of rotor laminations lie generally along a first axially extending line and the laterally outermost points of said skew portions of the corresponding slots in said second set of rotor laminations lie generally along a second axially extending line, the distance d between the first line and second line falling within a range expressed by the following equation,(2.pi.r)/(2S-P)<d.ltoreq.(2.pi.r)(2S-P)+.delta.+.rho.where r is the distance between the center of a rotor lamination and the laterally outermost point of the skew portions of one of the slots on the rotor lamination, and .rho./2 is approximately the distance between first and second parallel planes, the first plane including the radially outermost point of the slot and the second plane including the first or second axially extending line nearest the radially outermost point, the first and second planes being perpendicular to and intersecting a third plane including the first and second lines.