Permanent magnet motor and driving apparatus-integrated permanent magnet motor
A permanent magnet motor includes: a stator including: a stator core in which teeth are respectively arranged circumferentially so as to protrude radially inward from an annular core back; an armature winding that is mounted to the stator core; and a frame that holds the stator core in an internally fitted state; and a rotor that includes a rotor core and permanent magnets, the armature winding being constituted by a plurality of coils that are respectively wound so as to be concentrated on the teeth, wherein: inner circumferential ends of adjacent teeth are connected together by a connecting portion; and 0.122≦(t2+t3)/r4≦0.202 is satisfied, where t2 is a thickness of the core back, t3 is a thickness of the frame, and r4 is an outside radius of the frame.
1. A permanent magnet motor comprising:
a stator comprising:
a stator core in which teeth are respectively arranged circumferentially so as to protrude radially inward from an annular core back;
an armature winding that is mounted to said stator core; and
a frame that holds said stator core in an internally fitted state; and
a rotor that comprises a rotor core and permanent magnets;
said armature winding being constituted by a plurality of coils that are respectively wound to be concentrated on said teeth,
wherein:
inner circumferential ends of adjacent teeth are connected together by a connecting portion;
said frame is produced using aluminum or an aluminum alloy; and
0.122≦(t2+t3)/r4≦0.202 is satisfied, and 1.00≦t2/t3≦1.75 is satisfied, where t2 is a thickness of said core back, t3 is a thickness of said frame, and r4 is an outside radius of said frame.
2. The permanent magnet motor according to claim 1 , wherein 0.144≦(t2+t3)/r4≦0.202 is satisfied.
3. The permanent magnet motor according to claim 1 , wherein 2π·rout/(P·t2)≦5.20 is satisfied, where rout is an outside radius of said rotor, and P is a number of poles in said rotor.
4. The permanent magnet motor according to claim 1 , wherein 0.0211≦P·(t2+t3)·t2/(2π·rout·r4)≦0.0874 is satisfied, where rout is an outside radius of said rotor, and P is a number of poles in said rotor.
5. The permanent magnet motor according to claim 1 , wherein:
said stator core is configured by laminating steel sheets that have a sheet thickness tc;
0.5≦t0/tc≦2.0 is satisfied, where t0 is a radial thickness of said connecting portion.
6. The permanent magnet motor according to claim 1 , wherein said stator core is configured to be divided into:
an outer core that comprises said core back; and
an inner core that comprises said teeth and said connecting portion.
7. The permanent magnet motor according to claim 6 , further comprising coil bodies that are mounted to said teeth,
said coil bodies being configured by winding said coils onto tubular insulators that are mounted to said teeth in an externally fitted state.
8. The permanent magnet motor according to claim 1 , wherein said core back is formed such that, in a plane that is perpendicular to a central axis of said stator core, an outer circumference is a circle that is centered around said central axis, and an inner circumference is a circular arc that is centered around said central axis.
9. The permanent magnet motor according to claim 1 , wherein:
notch portions are respectively disposed on an outer circumferential surface of said core back at 3n positions at a uniform spacing circumferentially, to be each disposed at circumferentially central portions of said teeth, where n is an integer that is greater than or equal to 1; and
a number of poles P in said rotor is different than 3m, where m is an integer that is greater than or equal to 2.
10. The permanent magnet motor according to claim 1 , wherein said connecting portion is disposed partially in an axial direction.
11. The permanent magnet motor according to claim 1 , wherein:
an interfitting recess portion is formed on a first of an inner circumferential surface of said frame and an outer circumferential surface of said core back;
an interfitting protruding portion is formed on a second of said inner circumferential surface of said frame and said outer circumferential surface of said core back; and
said stator core is held on said frame by fitting together said interfitting recess portion and said interfitting protruding portion.
12. The permanent magnet motor according to claim 1 , wherein a number of poles in said rotor is fourteen, and a number of slots is eighteen.
13. A driving apparatus-integrated permanent magnet motor comprising:
said management magnet motor according to claim 12 ; and
an electronic control unit (ECU) portion that comprises:
switching elements that supply electric current to said armature winding; and
a heatsink on which said switching elements are disposed,
said ECU portion being configured integrally with said permanent magnet motor by fitting said heatsink together with said frame so as to be disposed so as to be coaxial to said permanent magnet motor.
14. The driving apparatus-integrated permanent magnet motor according to claim 13 , wherein:
said armature winding is constituted by:
a first armature winding that is formed by alternating-current connecting a portion of said plurality of coils; and
a second armature winding that is formed by alternating-current connecting a remaining portion of said plurality of coils; and
said ECU portion comprises:
a first inverter circuit that drives said first armature winding; and
a second inverter circuit that drives said second armature winding,
said first and second inverter circuits each being constituted by said switching elements.
15. The driving apparatus-integrated permanent magnet motor according to claim 13 , wherein said permanent magnet motor is mounted to an electric power steering apparatus such that an axial direction of said permanent magnet motor is parallel to a direction of movement of a rack shaft of said electric power steering apparatus.
16. The permanent magnet motor according to claim 1 , wherein a number of poles in said rotor is ten, and a number of slots is twelve.
17. A driving apparatus-integrated permanent magnet motor comprising:
said permanent magnet motor according to claim 16 ; and
an electronic control unit (ECU) portion that comprises:
switching elements that supply electric current to said armature winding; and
a heatsink on which said switching elements are disposed,
said ECU portion being configured integrally with said permanent magnet motor by fitting said heatsink together with said frame so as to be disposed so as to be coaxial to said permanent magnet motor.
18. A manufacturing method for a permanent magnet motor comprising:
a stator comprising:
a stator core in which teeth are respectively arranged circumferentially so as to protrude radially inward from an annular core back;
an armature winding that is mounted to said stator core; and
a frame that holds said stator core in an internally fitted state; and
a rotor that comprises a rotor core and permanent magnets,
said armature winding being constituted by a plurality of coils that are respectively wound to be concentrated on said teeth,
wherein:
inner circumferential ends of adjacent teeth are connected together by a connecting portion;
said frame is produced using aluminum or an aluminum alloy;
0.122≦(t2+t3)/r4≦0.202 is satisfied, and 1.00≦t2/t3≦1.75 is satisfied, where t2 is a thickness of said core back, t3 is a thickness of said frame, and r4 is an outside radius of said frame; and
at least one plastically deformed portion that is formed by pressing from an axially outer side is disposed in a circumferential direction on an axial end surface of said core back,
said deformed portion being formed by deforming said core back toward a radially outer side by pressing from said axially outer side on said axial end surface of said core back, after said stator core is fixed to said frame.