WE CLAIM:
1. A permanent magnet motor comprising:
a rotor (11) including a rotor iron core (12) and a plurality of permanent magnets (13) provided in the rotor iron core (12); and
a stator (21) including a stator iron core (22) and two sets of three-phase armature windings (30) provided in a plurality of slots (25) formed in the stator iron core (22), wherein
one set of the armature windings (30-1) is supplied with current from a first inverter (102-1), and the other set of the armature windings (30-2) is supplied with current from a second inverter (102-2),
in the case where a pole number of the rotor (11) is M and a slot number of the stator iron core (22) is Q, M and Q satisfy a relationship of M < Q and a greatest common divisor of M and Q is equal to or greater than 3,
in the rotor (11), the rotor iron core (12) is located on the stator (21) side beyond a radius intermediate between the maximum outer radius (Rmax) and the minimum inner radius (Rmin) of the permanent magnets (13), and
a phase difference between three-phase currents supplied from the first inverter (102-1) and three-phase currents supplied from the second inverter (102-2) is controlled to fall within a range of electrical angles of 20 to 40 degrees, wherein a M/2 number of the permanent magnets (13) are arranged along the circumferential direction of the rotor (11), where M is the pole number of the rotor (11),
characterized by
the stator iron core (22) having an open slot structure.
2. The permanent magnet motor as claimed in claim 1, wherein the armature windings (30-1, 30-2) are wound in a distributed manner, a value of Q/(3M) which is a slot number for each pole for each phase is an integer, and further, the value of Q/(3M) is an even number equal to or greater than 2.
3. The permanent magnet motor as claimed in claim 1, wherein the permanent magnets (13) have a planar shape.
4. The permanent magnet motor as claimed in claim 1, wherein the permanent magnets (13) are embedded in the rotor iron core (12).

5. The permanent magnet motor as claimed in claim 1, wherein the permanent magnets (13) have a shape in which a length thereof in a radial direction is greater than a length thereof in a circumferential direction, and are embedded in the rotor iron core (12).
6. The permanent magnet motor as claimed in claim 1, wherein the armature windings are wound in a concentrated manner, a protruding portion made of magnetic material is present between the adjacent permanent magnets (13) of the rotor (11), and an outer side of the protruding portion in a radial direction protrudes toward the stator (21) side beyond a radius intermediate between the maximum outer radius (Rmax) and the minimum inner radius (Rmin) of the permanent magnets (13).
7. The permanent magnet motor as claimed in claim 1, wherein the permanent magnets (13) are provided at a surface of the rotor iron core (12).
8. The permanent magnet motor as claimed in claim 4, wherein slits (19a-19d) formed symmetrically with respect to a magnetic pole center of the rotor (11) are provided in the rotor iron core (12).
9. The permanent magnet motor as claimed in claim 5, wherein slits (19e-19h) formed symmetrically with respect to a center line of each permanent magnet are provided in the rotor iron core (12).
10. The permanent magnet motor as claimed in claim 5, wherein
the rotor iron core (12) in the vicinity of a portion corresponding to an N pole and a portion corresponding to an S pole of the rotor iron core (12), which are formed in accordance with the magnetization directions of the permanent magnets (13), is formed in a shape not being rotationally symmetric, and
a surface (20a, 20b) of the rotor iron core (12) has a curved-plane shape symmetric with respect to a center line of each permanent magnet (13).
11. The permanent magnet motor as claimed in claim 1, wherein a phase difference
between three-phase currents supplied from the first inverter (102-1) and three-phase
currents supplied from the second inverter (102-2) is controlled to be an electrical
angle of 30 degrees.

12. The permanent magnet motor as claimed in claim 5, wherein a residual magnetic flux density of each permanent magnet (13) is equal to or smaller than 1T.
13. An electric power steering apparatus comprising the permanent magnet motor as claimed in any one of claims 1 to 12.
14. A permanent magnet motor for electric power steering apparatus, in which an ECU (control unit) (101) is integrally provided in back of the permanent magnet motor (10) as claimed in any one of claims 1 to 12, wherein
a sensor with a shaft angle multiplier of 1X is used for a rotational angle sensor (111) of the motor (10), and
a pole pair number of the motor (10) is equal to or greater than 3.
15. A permanent magnet motor for electric power steering apparatus, in which an ECU
(control unit) (101) is integrally provided in back of the permanent magnet motor (10)
as claimed in any one of claims 1 to 12, wherein
a VR resolver with a shaft angle multiplier of NX is used for a rotational angle sensor (111) of the motor (10), and
a pole pair number N of the motor (10) is equal to or greater than 3.