US 5,753,991 AGranted

Multiphase brushless AC electric machine

AssigneeHydro-Quebec

InventorsPierre Couture, Bruno Francoeur

Life of this patent

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Abstract

The multiphase brushless AC electric machine comprises a stator frame having a surface provided with parallel slots and projections disposed alternately, each of the openings being substantially as wide as the widest width of the corresponding slot; and a rotor frame having a surface provided with permanent magnet means having respective surface sections facing the slots and projections. All of the surface sections of the magnet means produce a magnetic flux density having a component average amplitude B.sub.r (.theta.) perpendicular to the corresponding surface of the stator, which is substantially defined by the following equation: B.sub.r (.theta.)=M.sub.r (.theta.).multidot.L.sub.a (.theta.)/L.sub.v (.theta.) where L.sub.a (.theta.) is defined by the following equation: ##EQU1## where .theta. is a position angle in radians with respect to a reference position on the rotor frame; B.sub.r (.theta.) is the component average amplitude at the position angle .theta.; L.sub.v (.theta.) is a gap distance between the projections and the surface of the rotor frame at the position angle .theta.; M.sub.r (.theta.) is a component of residual induction of the magnet means at the position angle .theta., M.sub.r (.theta.) being perpendicular to the corresponding surface of the stator, M.sub.r (.theta.) being alternative with a period corresponding to 4.pi./K; K is an even number representative of all of the surface sections; and C is an arbitrary constant. The present invention is also concerned with a method of operating the multiphase brushless AC electric machine.

Claims20

Dependent claims

A multiphase brushless AC electrical machine comprising:

a stator frame having a surface provided with parallel slots and projections disposed alternately, each of said slots having an opening onto said surface, each of said openings being substantially as wide as the widest width of the corresponding slot, the stator frame having winding conductors mounted within the slots;
and
a rotor frame having a surface provided with permanent magnet means having respective surface sections facing said slots and projections, each of said surface sections facing a number of said slots which corresponds to a number of phases upon which said machine operates, all of said surface sections of said magnet means producing a magnetic flux density having a component average amplitude B.sub.r (.theta.) perpendicular to the corresponding surface of the stator, which is substantially defined by the following equation:
B.sub.r (.theta.)=M.sub.r (.theta.).multidot.L.sub.a (.theta.)/L.sub.v (.theta.)
where L.sub.a (.theta.) is defined by the following equation:
##EQU12## where .theta. is a position angle in radians with respect to a reference position on said rotor frame;
B.sub.r (.theta.) is said component average amplitude at said position angle .theta.;
L.sub.a (.theta.) is a gap distance between said projections and said surface of said rotor frame at said position angle .theta.;
M.sub.r (.theta.) is a component of residual induction of said magnet means at said position angle .theta., M.sub.r (.theta.) being perpendicular to the corresponding surface of the stator, M.sub.r (.theta.) being alternative with a period corresponding to 4.pi./K;
K is an even number representative of all of said surface sections;
and C is an arbitrary constant, whereby, in operation, said rotor frame is magnetically coupled to said stator frame while reducing losses due to harmonic distortion of magnetic flux density within said stator frame, having a torque versus current curve that is linear for a larger current band and reducing cogging torque between said stator frame and said rotor frame.

8 more elements

A method of operating a multiphase brushless AC electric machine, comprising the steps of:

magnetically coupling a stator frame provided with windings with a rotor frame, the stator frame having a surface provided with parallel slots and projections disposed alternately, each of said slots having an opening onto said surface, each of said openings being substantially as wide as the widest width of the corresponding slot, the windings being mounted within the slots, the rotor frame having a surface provided with permanent magnet means having respective surface sections facing said slots and projections, each of said surface sections facing a number of said slots which corresponds to a number of phases upon which said machine operates, all of said surface sections of said magnet means producing a magnetic flux density having a component average amplitude B.sub.r (.theta.) perpendicular to the corresponding surface of the stator, which is substantially defined by the following equation:
B.sub.r (.theta.)=M.sub.r (.theta.).multidot.L.sub.a (.theta.)/L.sub.v (.theta.)
where L.sub.a (.theta.) is defined by the following equation:
##EQU13## where .theta. is a position angle in radians with respect to a reference position on said rotor frame;
B.sub.r (a) is said component average amplitude at said position angle .theta.;
L.sub.v (.theta.) is a gap distance between said projections and said surface of said rotor frame at said position angle .theta.;
M.sub.r (.theta.) is a component of residual induction of said magnet means at said position angle .theta., M.sub.r (.theta.) being perpendicular to the corresponding surface of the stator, M.sub.r (.theta.) being alternative with a period corresponding to 4.pi./K;
K is an even number representative of all of said surface sections;
and C is an arbitrary constant;
and
energizing the windings of the stator, whereby, in operation, said rotor frame is magnetically coupled to said stator frame while reducing losses due to harmonic distortion of magnetic flux density within said stator frame, having a torque versus current curve that is linear for a larger current band and reducing cogging torque between said stator frame and said rotor frame.

8 more elements

Dependencies are inferred from the claim text.

Facts

Application: 08/353,241Filed 2 Dec 1994
Granted: 19 May 1998
Term ends: Not estimatedThe source records don’t support an estimate.

Classification5 codes

H02K 29/03
Motors or generators having non-mechanical commutating devices, e.g. discharge tubes or semiconductor devices: with a magnetic circuit specially…
H02K 1/165
Stator cores with slots for windings: shape, form or location of the slots
H02K 1/27915
Surface mounted magnets; Inset magnets: magnets shaped to vary the mechanical air gap between the magnets and the stator
H02K 21/12
Synchronous motors having permanent magnets; Synchronous generators having permanent magnets: with stationary armatures and rotating magnets