High efficiency induction motor with multi-cage rotor

An induction motor comprising a stator core having winding turns supported and positioned thereon to establish a fundamental magnetic field of a number of instantaneous fundamental magnetic poles during energization, and a rotor comprising a magnetic core and a plurality of longitudinally extending conductors that inductively couple with the fundamental pole structure of the fundamental magnetic field and that are arranged along the magnetic core in a predetermined pattern so as to form a number n of different cage sets with the longitudinally extending conductors in each set short circuited one to the other in each such set at the ends thereof by end conductors;

• next adjacent longitudinally extending conductors within each cage set being spaced apart a distance substantially equal to twice the pitch, in fundamental electrical degrees, of an odd space harmonic of the fundamental magnetic field so that inductive coupling of the same odd space harmonic of the fundamental magnetic field and a rotor circuit established by the longitudinally extending conductors and end conductors is substantially prevented.

An induction motor comprising a stator core having winding turns supported and positioned thereon to establish a magnetic field of at least six instantaneous fundamental magnetic poles during energization, and a rotor comprising a magnetic core and a plurality of conductors that inductively couple with the fundamental pole structure of the fundamental magnetic field and that are arranged along the magnetic core in a predetermined pattern so as to form a plurality of cage sets with the conductors in each set short circuited one to the other in each such set at the ends thereof by conductor means;

• next adjacent conductors within each such cage set being spaced apart a distance substantially equal to twice the pitch, in fundamental electrical degrees, of an odd space harmonic of the fundamental magnetic field;
• said motor including winding connections that are provided so that only a portion of the winding turns may be selectively energized to provide an operating point other than the operating point that is provided when all of the winding turns are energized;
• and wherein the motor is of the shaded pole type.

An induction motor comprising a stator core having winding turns supported and positioned thereon to establish a magnetic field of at least six instantaneous fundamental magnetic poles during energization, and a rotor comprising a magnetic core and a plurality of conductors that inductively couple with the fundamental pole structure of the fundamental magnetic field and that are arranged along the magnetic core in a predetermined pattern so as to form a plurality of cage sets with the conductors in each set short circuited one to the other in each such set at the ends thereof by conductor means;

• next adjacent conductors within each such cage set being spaced apart a distance substantially equal to twice the pitch, in fundamental electrical degrees, of an odd space harmonic of the fundamental magnetic field;
• said motor including winding connections that are provided so that only a portion of the winding turns may be selectively energized to provide an operating point other than the operating point that is provided when all of the winding turns are energized;
• and wherein the motor is of the permanent capacitor type.

An induction motor comprising a stator assembly having a magnetic core and winding turns that establish a number N of instantaneous fundmental magnetic poles during excitation of the winding turns, and a rotor comprising a magnetic core having a plurality of angularly spaced apart conductor accommodating slots extending between first and second ends thereof, a minimum total number M of conductos disposed in M different uniformly agnularly spaced apart ones of said slots and extending between said first and second ends, a number A of conductors disposed at the first end of the core, and a number B of conductos disposed at the second end of the core;

• with said conductors arranged in a pattern to form a number n of different cage sets of conductors selectively connected to a conductor at each end of the rotor core so that the conductors of each set are connected in short circuit relation with the other conductors of the same set through a conductor at each end of the rotor, with next adjacent conductors within each set spaced apart two-thirds of a fundamental pole pitch and the number n selected to be an odd integer at least equal to the number three;
• and wherein the number M is at least equal to the quantity 4.5 .times. N, and the product A .times. B is at least equal to the number n.

A rotor adapted for use in a motor having a stator that establishes a magnetic field of a predetermined number of fundamental magnetic poles during operation, the rotor comprising a number of first conductors, per fundamental pole, that is equal to an integer plus one-half;

• said rotor further comprising a plurality of second conductors;
• said first conductors being arranged in cage sets and interconnected at the ends thereof to selected ones of the plurality of second conductors so that next adjacent ones of the first conductors within each cage set are spaced apart a distance substantially equal to twice the pitch, in fundamental electrical degrees, of a preselected odd space harmonic of the magnetic field, so that coupling of the preselected odd space harmonic of the magnetic field with a rotor circuit established by the first and second conductors is substantially prevented.