Means to reduce harmonic torque in electromagnetic machines

An electromagnetic machine, comprising:

• (a) a rotor having a cylindrical, axially-magnetized magnet with cylindrical pole pieces on the ends thereof, the pole pieces having equally-spaced longitudinal teeth formed on their peripheries, the teeth of one pole piece being radially displaced from the teeth on the other pole piece by one-half tooth pitch plus an angle, .alpha..sub.m ;
• (b) a set of stator poles radially disposed about the rotor to magnetically interact with the rotor;
• and
• (c) where:
• .alpha..sub.m =.alpha..sub.e /p,
• where
• .alpha..sub.e =displacement in electrical degrees,
• p=number of rotor magnetic pole pairs,
• further where
• .alpha..sub.e =180/h,
• where h=an integer equal to the number of a harmonic of the fundamental torque/angle curve to be attenuated.

An electromagnetic machine, comprising:

• (a) an untoothed rotor having a cylindrical, radially magnetized surface with two sets of alternate N and S magnetic poles displaced symmetrically thereon, the poles of one set being radially displaced from the poles of the other set, such that an N pole of one set is displaced from the corresponding N pole of the other set by one-half pole pitch plus an angle, .alpha..sub.m ;
• (b) a set of stator poles radially disposed about the rotor to magnetically interact with the rotor;
• and
• (c) where:
• .alpha..sub.m =.alpha..sub.e /p,
• where .alpha..sub.e =displacement in electrical degrees,
• p=number of rotor magnetic pole pairs,
• further where
• .alpha..sub.e =180/h,
• where h=an integer equal to the number of a harmonic of the fundamental torque/angle curve to be attenuated.

An electromagnetic machine, comprising:

• (a) a rotor having two axially-aligned, axially-magnetized, cylindrical magnets, each having a cylindrical pole piece on each end thereof, the magnets and pole pieces being in axial alignment, the pole pieces having uniform and equally-spaced teeth on their peripheries, the teeth of one pole piece on each magnet being displaced from the teeth of the other pole piece on each magnet by one-half tooth pitch, and the teeth of the pole pieces on one magnet being radially displaced from the teeth of the corresponding pole pieces on the other magnet by an angle, .alpha..sub.m ;
• (b) a set of stator poles radially disposed about the rotor to magnetically interact with the rotor;
• and
• (c) where;
• .alpha..sub.m =.alpha..sub.e /p,
• where .alpha..sub.e =displacement in electrical degrees,
• p=number of rotor magnetic pole pairs,
• further where
• .alpha..sub.e =180/h,
• where h=an integer equal to the number of a harmonic of the fundamental torque/angle curve to be attenuated.

An electromagnetic machine, comprising:

• (a) a toothed, axially-magnetized rotor;
• (b) a set of stator poles radially disposed about the rotor to magnetically interact with the rotor, the stator poles being axially divided into two sections, with one section being radially displaced from the other section by one-half a rotor tooth pitch plus an angle, .alpha..sub.m ;
• and
• (c) where:
• .alpha..sub.m =.alpha..sub.e /p,
• where .alpha..sub.e =displacement in electrical degrees,
• p=number of rotor magnetic pole pairs,
• further where
• .alpha..sub.e =180/h,
• where h=an integer equal to the number of a harmonic of the fundamental torque/angle curve to be attenuated.

An electromagnetic machine, comprising:

• (a) a toothed, axially-magnetized rotor;
• (b) a set of stator poles radially disposed about the rotor to magnetically interact with the rotor, the stator poles having teeth on the surface facing the rotor, the stator poles being axially divided into sections, and the teeth on one section being radially displaced from the teeth on the other section by one-half a rotor tooth pitch plus an angle .alpha..sub.m ;
• and
• (c) where:
• .alpha..sub.m =.alpha..sub.e /p,
• where
• .alpha..sub.e =displacement in electrical degrees,
• p=number of rotor magnetic pole pairs,
• further where
• .alpha..sub.e =180/h,
• where h=an integer equal to the number of a harmonic of the fundamental torque/angle curve to be attenuated.

An electromagnetic machine, comprising:

• (a) a rotor having a cylindrical, axially-magnetized magnet with cylindrical pole pieces on the ends thereof, the pole pieces having equally-spaced longitudinal teeth formed on their peripheries, the teeth of one pole piece being radially displaced from the teeth on the other pole piece by one-half tooth pitch minus an angle, .alpha..sub.m ;
• (b) a set of stator poles radially disposed about the rotor to magnetically interact with the rotor;
• and
• (c) where:
• .alpha..sub.m =.alpha..sub.e /p,
• where .alpha..sub.e =displacement in electrical degrees,
• p=number of rotor magnetic pole pairs,
• further where
• .alpha..sub.e =180/h,
• where h=an integer equal to the number of a harmonic of the fundamental torque/angle curve to be attenuated.

An electromagnetic machine, comprising:

• (a) an untoothed rotor having a cylindrical, radially magnetized surface with two sets of alternate N and S magnetic poles displaced symmetrically thereon, the poles of one set being radially displaced from the poles of the other set, such that an N pole of one set is radially displaced from the corresponding N pole of the other set by one-half pole pitch minus an angle, .alpha..sub.m ;
• (b) a set of stator poles radially disposed about the rotor to magnetically interact with the rotor;
• and
• (c) where:
• .alpha..sub.m =.alpha..sub.e /p,
• where .alpha..sub.e =displacement in electrical degrees,
• p=number of rotor magnetic pole pairs,
• further where
• .alpha..sub.e =180/h,
• where h=an integer equal to the number of a harmonic of the fundamental torque/angle curve to be attenuated.

An electromagnetic machine, comprising:

• (a) a toothed, axially-magnetized rotor;
• (b) a set of stator poles radially disposed about the rotor to magnetically interact with the rotor, the stator poles being axially divided into two sections, with one section being radially displaced from the other section by one-half a rotor tooth pitch minus an angle, .alpha..sub.m ;
• and
• (c) where:
• .alpha..sub.m =.alpha..sub.e /p,
• where .alpha..sub.e =displacement in electrical degrees,
• p=number of rotor magnetic pole pairs,
• further where
• .alpha..sub.e =180/h,
• where h=an integer equal to the number of a harmonic of the fundamental torque/angle curve to be attenuated.

An electromagnetic machine, comprising:

• (a) a toothed, axially-magnetized rotor;
• (b) a set of stator poles radially disposed about the rotor to magnetically interact with the rotor, the stator poles having teeth on the surface facing the rotor, the stator poles being axially divided into sections, and the teeth on one section being displaced from the teeth on the other section by one-half a rotor tooth pitch minus an angle, .alpha..sub.m ;
• and
• (c) where:
• .alpha..sub.m =.alpha..sub.e /p,
• where .alpha..sub.e =displacement in electrical degrees,
• p=number of rotor magnetic pole pairs,
• further where
• .alpha..sub.e =180/h,
• where h=an integer equal to the number of a harmonic of the fundamental torque/angle curve to be attenuated.