WE CLAIM:
1. An electric driving apparatus comprising:
a rotary electric machine that comprises: a stator that comprises:
a stator core in which a plurality of teeth are arranged in a circumferential direction such that each protrudes radially inward from an inner circumferential surface of an annular core back; and
a first armature winding and a second armature winding that are configured by connecting a plurality of coils that are wound into concentrated windings on each of said teeth, said first armature winding and said second armature winding not being connected to each other electrically; a rotor that comprises:
a plurality of permanent magnets that are disposed in a circumferential direction so as to be spaced apart from each other, and so as to have directions of magnetization oriented in said circumferential direction; a plurality of field pole portions that are disposed between respective adjacent pairs of permanent magnets; and
a plurality of nonmagnetic portions that are disposed on a radially inner side of said permanent magnets so as to contact each of said plurality of permanent magnets, said rotor being disposed radially inside said stator core so as to have a magnetic air gap portion interposed; and a controlling apparatus that comprises:
a first inverter that supplies inverter phase currents to said first armature winding;
a second inverter that supplies inverter phase currents to said second armature winding; and
a control portion that controls driving of said first inverter and said second inverter, wherein:
55

coils that constitute said first armature winding and coils that constitute said second armature winding are arranged so as to alternate in said circumferential direction;
said control portion is configured so as to:
perform two-system driving when a first system that comprises said first armature winding and said first inverter and a second system that comprises said second armature winding and said second inverter are normal, said two-system driving controlling driving of said first inverter and said second inverter to supply said inverter phase currents to said first armature winding and said second armature winding such that said inverter phase currents are set to a first upper limit value, and
perform single-system driving when one of said first system and said second system fails, said single-system driving stopping driving of said inverter of said system that has failed, and controlling driving of said inverter of said system that has not failed to supply said inverter phase currents to said armature winding of said system that has not failed such that said inverter phase currents are set to a second upper limit value that is greater than said first upper limit value.
2. The electric driving apparatus according to Claim 1, wherein during said two-system driving said second upper limit value is set to a value that is greater than an inverter phase current value that places demagnetizing fields that arise in said permanent magnets in an irreversibly demagnetizing field region.
3. The electric driving apparatus according to Claim 1 or Claim 2, wherein said second upper limit value is greater than one times said first upper limit value and less than or equal to two times said first upper limit value.
4. The electric driving apparatus according to any one of Claims 1 through 3, wherein said plurality of field pole portions are linked by bridge portions that are constituted by magnetic bodies.
5. The electric driving apparatus according to any one of Claims 1 through 4, wherein respective surfaces of said plurality of field pole portions
56

that face said stator are formed so as to have curved surfaces that have radially outwardly convex shapes that minimize an air gap length from said stator at intermediate positions between adjacent permanent magnets.
6. The electric driving apparatus according to any one of Claims 1 through 5, wherein a number of field poles is greater than or equal to a number of said teeth.
7. The electric driving apparatus according to any one of Claims 1 through 5, wherein:
P = (18 ± 4)n; and N = 18n
where P is said number of field poles, N is said number of said teeth, and n is a positive integer.
8. The electric driving apparatus according to any one of Claims 1
through 5, wherein:
P = (18 ± 2)n; and N = 18n
where P is said number of field poles, N is said number of said teeth, and n is a positive integer.
9. The electric driving apparatus according to any one of Claims 1
through 5, wherein:
P = (12 ± 2)n; and N = 12n
where P is said number of field poles, N is said number of said teeth, and n is a positive integer.
10. The electric driving apparatus according to any one of Claims 1
through 5, wherein:
P = (6 ± 2)n; and N = 6n
where P is said number of field poles, N is said number of said teeth, and n is a positive integer.
57

11. The electric driving apparatus according to any one of Claims 1 through 10, wherein a low magnetic permeability portion is formed on each of said plurality of field pole portions so as to extend in a radial direction and to extend from a first axial end to a second axial end.
12. An electric power steering apparatus to which the electric driving apparatus according to any one of Claims 1 through 11 is mounted.
58