PERMANENT MAGNET SYNCHRONOUS MOTOR HAVING A LOW DEMAGNETIZATION FACTOR
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Abstract
To obtain a permanent magnet synchronous motor suitable for an electric power steering system, in which the magnet thickness (magnet used amount) can be reduced while securing demagnetization resistance and torque characteristics. In a permanent magnet synchronous motor including a rotor in which plural permanent magnets are arranged at an outer periphery of a rotor core, which is supported so as to rotate freely, and a stator provided at the outside of the stator and having stator windings 5 and a stator core, when a gap length between the outer periphery of the permanent magnet and an internal periphery of the stator core is “L” [mm] and the thickness of the central portion of the permanent magnet in the motor rotation direction is “t” [mm], the gap length “L” and the thickness “t” is set in a range of
L≦1[mm] as well as t/(t+L)≦0.9
2 Citations
16 Claims
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1-10. -10. (canceled)
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11. A permanent magnet synchronous motor, comprising:
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a rotor having a rotor core in which plural NdFe rare-earth segment permanent magnets are provided at an outer periphery, supported so as to rotate freely; and a stator having stator windings and a stator core, provided at the outside of the rotor through a gap, wherein, when a gap length between the outer periphery of the permanent magnet and an inner periphery of the stator core is “
L”
(mm) and a thickness of the central portion of the permanent magnet in the motor rotation direction is “
t”
(mm), the gap length “
L” and
the thickness “
t”
are set in a range of
L=0.6 to 0.7 mm,t(t+L)=0.77 to 0.85.wherein the thickness of both end portions of the permanent magnet “
e”
(mm) is set in a range of 0.4≦
e/t≦
0.70wherein, when the number of poles of the permanent magnets is “
P”
, and the number of slots of the stator is “
N”
, the number of poles “
P” and
the number of slots “
N”
are set so that;P;
N=5n;
6n or 7n;
6n (“
n”
is an integer equal to 2 or more) andwherein remanent flux density Br of the permanent magnet is set in a range of
Br≧
1.2T. - View Dependent Claims (12, 13, 14, 15, 16)
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Specification