Classifications

• • H—ELECTRICITY
  • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
  • H02K—DYNAMO-ELECTRIC MACHINES
  • H02K1/00—Details of the magnetic circuit
  • H02K1/06—Details of the magnetic circuit characterised by the shape, form or construction
  • H02K1/22—Rotating parts of the magnetic circuit
  • H02K1/27—Rotor cores with permanent magnets
  • H02K1/2706—Inner rotors
  • H02K1/272—Inner rotors the magnetisation axis of the magnets being perpendicular to the rotor axis
  • H02K1/274—Inner rotors the magnetisation axis of the magnets being perpendicular to the rotor axis the rotor consisting of two or more circumferentially positioned magnets
  • H02K1/2753—Inner rotors the magnetisation axis of the magnets being perpendicular to the rotor axis the rotor consisting of two or more circumferentially positioned magnets the rotor consisting of magnets or groups of magnets arranged with alternating polarity
  • H02K1/276—Magnets embedded in the magnetic core, e.g. interior permanent magnets [IPM]

Definitions

• Embodiments of the present disclosure generally relate to a motor filed, more particularly, to a permanent magnet motor.
• a permanent magnet motor in related art includes a stator and a rotor, the rotor includes a rotor core and permanent magnets disposed in the rotor core, and a rare earth permanent magnet with high residual magnetism is generally used as a permanent-magnet pole of the permanent magnets.
• the Chinese patent Application CN 102171909 discloses a permanent magnet motor including four poles, and four permanent magnets are disposed on four edges of the motor core to configure as two pairs of the permanent magnets which are arranged up-down and left-right respectively so as to form a substantially square structure.
• the magnetic fields start from the N poles of the permanent magnets arranged up-down, and arrive at the S poles of the permanent magnets arranged left-right; and the magnetic fields start from the N poles of the permanent magnets arranged left-right, and arrive at the S poles of the permanent magnets arranged up-down, thus forming four complete magnetic circuits for normal operation of the rotor core.
• How to reduce the cost of the motor while ensuring the original performance of the motor is a problem for a manufacturer. Since the cost of permanent magnets accounts for a large proportion of the total cost of the motor, many technicians have attempted to reduce the cost by improving the structure and size of the permanent magnet.
• Embodiments of the present disclosure seek to provide a permanent magnet motor with a low cost and a good operating performance.
• a permanent magnet motor comprising: a stator and a rotor, and the rotor comprising: a rotor core having at least two receiving recesses, a groove defining a first end and a second end formed on each end of each of the receiving recesses and communicated therewith, wherein a central angle whose vertex is a center of the rotor core and whose sides pass through the second ends of the two grooves located on each of the receiving recesses is a, a central angle whose vertex is the center of the rotor core and whose sides pass through the first end of one groove of one receiving recess and the first end of one groove of another receiving recess adjacent to the one groove of the one receiving recess is ⁇ , and a ratio of a to ⁇ ranges from 0.8 to 1.2; and permanent magnets received in the receiving recesses respectively, wherein a magnetic field of any permanent magnet does not cross over other permanent magnets.
• the receiving recess has a first surface close to the center of the rotor core and a second surface away from the center of the rotor core
• the groove comprises a first groove segment and a second groove segment, a free end of the first groove segment configured as the first end of the groove extends beyond the first surface of the receiving recess, and a free end of the second groove segment configured as the second end of the groove extends beyond the second surface of the receiving recess.
• a width of the second groove segment is Wl
• a distance between an outer surface of the second groove segment and an outer edge of the rotor core is W2
• a ratio of Wl to W2 ranges from 0.9 to 1.1.
• a width of the first groove segment is W3 and a distance between an outer surface of the first groove segment and the outer edge of the rotor core is W2, a ratio of W3 to W2 ranges from 2.0 to 3.0.
• a ranges from 52° to 64°.
• a is 60°.
• a permanent magnet motor comprising a rotor and the rotor comprises: a rotor core having at least two receiving recesses, a groove defining a first end and a second end formed on each end of each of the receiving recesses and communicated therewith, wherein a central angle whose vertex is a center of the rotor core and whose sides pass through the second ends of the two grooves located on any one of the receiving recesses is a, a central angle whose vertex is the center of the rotor core and whose sides pass through the first end of one groove of one receiving recess and the first end of one groove of another receiving recess adjacent to the one groove of the one receiving recess is ⁇ , and a ratio of a to ⁇ ranges from 0.8 to 1.2; and permanent magnets received in the receiving recesses respectively, wherein an N or S pole of each permanent magnet faces towards an outer edge of the rotor core.
• the receiving recess has a first surface close to the center of the rotor core and a second surface away from the center of the rotor core
• the groove comprises a first groove segment and a second groove segment, a free end of the first groove segment configured as the first end of the groove extends beyond the first surface of the receiving recess, and a free end of the second groove segment configured as the second end of the groove extends beyond the second surface of the receiving recess.
• a width of the first groove segment is greater than that of the second groove segment.
• a width of the second groove segment is Wl
• a distance between an outer surface of the second groove segment and an outer edge of the rotor core is W2
• a ratio of Wl to W2 ranges from 0.9 to 1.1.
• a width of the first groove segment is W3 and a distance between an outer surface of the first groove segment and the outer edge of the rotor core is W2, a ratio of W3 to W2 ranges from 2.0 to 3.0.
• a is 60°.
• the permanent magnet motor according to embodiments of the present invention may reduce the cost by removing the auxiliary permanent magnets, and ensure the electromagnetic torque of the permanent magnet motor and greatly reduce the torque fluctuation by setting a relationship of a and ⁇ .
• the electromagnetic torque of the permanent magnet motor also may be dramatically improved according to the relationship of a and ⁇ .
• Fig. 1 is a schematic view of a permanent magnet motor according to a first embodiment of the present invention
• Fig. 2 is a schematic view of a rotor of the permanent magnet motor as shown in Fig. 1;
• Fig. 3 is a diagram illustrating the relationship of the electromagnetic torque fluctuation of the permanent magnet motor and ⁇ , ⁇ of the rotor of the permanent magnet motor as shown in Fig. 1;
• Fig. 4 is another diagram illustrating the relationship of the electromagnetic torque fluctuation of the permanent magnet motor and ⁇ , ⁇ of the rotor of the permanent magnet motor as shown in Fig. 1;
• Fig. 5 is a diagram illustrating the comparison of the electromagnetic torques of the permanent magnet motor in the embodiments of the present invention and the permanent magnet motor in the related art, in which ⁇ of the rotors of both of the permanent magnet rotors is 60°;
• Fig. 6 is a schematic view of a rotor of the permanent magnet motor according to a second embodiment of the present invention.
• Fig. 7 is a schematic view of a rotor of the permanent magnet motor according to a third embodiment of the present invention.
• Fig. 8 is a schematic view of a rotor of the permanent magnet motor according to a fourth embodiment of the present invention.
• Fig. 9 is a schematic view of a permanent magnet motor according to an embodiment of the present invention.
• Fig. 10 is a schematic view of a rotor of an external rotor permanent magnet motor according to an embodiment of the present invention.
• the permanent magnet 100 includes a stator 1 and a rotor 2 disposed in the stator 1.
• the stator 1 includes an outer edge portion 11, a plurality of stator teeth 12 extending from an inner surface of the outer edge portion 11 to a circle center of the outer edge portion 11 and a plurality of winding grooves 13 formed between the stator teeth 12.
• the outer edge portion is annular
• the stator tooth 12 includes a winding portion 121 connected with the outer edge portion 11 and a pole shoe 122 extending inwardly from an end (inner end) of the winding portion 121 in the opposite directions (i.e. the directions to adjacent winding grooves 13).
• the stator teeth 12 and the winding grooves 13 are alternately arranged on the inner side of the outer edge portion 11 uniformly and an angular pitch of the stator teeth 12 adjacent to each other is ⁇ , namely, a central angle whose vertex is a center O of the rotor 2 (i.e., a center of the rotor core 21 and a central hole 20) and whose sides are radial central lines XI of the stator teeth 12 adjacent to each other is ⁇ .
• a groove pitch of adjacent winding grooves 13 also is ⁇ , i.e., a central angle whose vertex is the center O of the rotor 2 and whose sides are radial central lines X2 of the winding grooves 12 adjacent to each other also is ⁇ .
• the number of the stator teeth 12 or of the winding grooves 13 is 6, and ⁇ is 60°.
• the rotor 2 includes a rotor core 21 having receiving recesses 211 and permanent magnets 22 received in the receiving recesses 211.
• the receiving recess 211 includes a first surface 2111 close to the center hole 20 of the rotor core 21 and a second surface 2112 away from the center hole 20 of the rotor core 21, and the first surface 2111 and the second surface 2112 are parallel to each other.
• the first surface 2111 is the lower surface and the second surface 2112 is the upper surface; and for the lower receiving recess 211, the first surface 2111 is the upper surface and the second surface 2112 is the lower surface.
• the shape of the permanent magnet is a substantial rectangle, but is not limited to this.
• the N pole of the permanent magnet 22 is away from the central hole 20 and faces towards an outer edge of the rotor core 21, and the S pole of the permanent magnet 22 is close to the central hole 20.
• the number of the receiving recesses 211 may be two, and the two receiving recesses 211 are located on two sides of the central hole 20 of the rotor core 21 and parallel to each other.
• the S pole of the permanent magnet 22 may be disposed away from the central hole 20, and the N pole of the permanent magnet 22 may be disposed close to the central hole 20.
• a groove 212 extends outward from two ends (the right end and the left end in Fig. 1) of the receiving recess 211 and is communicated therewith.
• Each groove 212 on the end of the receiving recess 211 includes a first groove segment 2121 extending toward another receiving recess 211 and a second groove segment 2122 extending away from the another receiving recess 211.
• a free end of the first groove segment 2121 is configured as a first end 2123 of the groove 212
• a free end of the second groove segment 2122 is configured as a second end 2124 of the groove 212.
• a magnetic field of any permanent magnet does not cross over other permanent magnets, i.e., a magnetic field of one permanent magnet 22 starts from the N pole thereof and arrives at the S pole of the same permanent magnet 22, which is not interfered by another permanent magnet 22, or the interference is too tiny to be noticed.
• the permanent magnet motor includes only two permanent magnets 22 without auxiliary permanent magnets.
• the back-electromotive force waveform of the rotor 2 is not symmetrical due to the omission of the other pair of permanent magnets which may be called auxiliary permanent magnets, so that the electromagnetic torque of the rotor 2 fluctuates wildly.
• auxiliary permanent magnets which may be called auxiliary permanent magnets
• the grooves 212 each consisting of the first groove segment 2121 and the second groove segment 2122 are disposed at the ends of the receiving recess 211, which may effectively improve the electromagnetic torque of the permanent magnet motor, avoid the defect of asymmetry of the back-electromotive force waveform due to the omission of another pair of permanent magnets, and reduce the electromagnetic torque fluctuation of the rotor.
• the first end 2123 of the first groove segment 2121 extends beyond the first surface 2111 of the receiving recess 211, and the second end 2124 of the second groove segment 2122 extends beyond the second surface 2112 of the receiving recess 211.
• a width W3 of the first groove segment 2121 is greater than a width Wl of the second groove segment 2122.
• a central angle whose vertex is the center O of the rotor core 21 and whose sides pass through the second ends 2124, which are away from the first groove segments 2121, of the second groove segments 2122 located on any one of the receiving recesses 211 is a
• a central angle whose vertex is the center O of the rotor core 21 and whose sides pass through the first end 2123 (away from the second groove segment 2122) of one first groove segment 2121 of one receiving recess 211 and the first end 2123 (away from the second groove segment 2122) of one first groove segment 2123 of another receiving recess 211 adjacent to the one first groove segment 2121 of the one receiving recess 211 is ⁇ .
• the inventors discover that when the ratio of a to ⁇ ranges from 0.8 to 1.2, the electromagnetic torque of the rotor 2 is maintained at a high value, while the electromagnetic torque fluctuation of the permanent magnet motor 100 is very slight.
• Fig. 3 is a diagram illustrating the relationship of the electromagnetic torque fluctuation of the permanent magnet motor and ⁇ , ⁇ of the rotor of the permanent magnet motor.
• the line I indicates a fluctuation range of the electromagnetic torque when a is 52° and ⁇ is a variable angle;
• the line II indicates a fluctuation range of the electromagnetic torque when a is 60° and ⁇ is a variable angle;
• the line III indicates a fluctuation range of the electromagnetic torque when a is 64° and ⁇ is a variable angle. It may be seen from Fig. 3 that when ⁇ is around 60°, the fluctuation range of the electromagnetic torque of the permanent magnet motor reaches a desirable state.
• Fig. 4 is another diagram illustrating the relationship of the electromagnetic torque fluctuation of the permanent magnet motor and ⁇ , ⁇ of the rotor of the permanent magnet motor.
• the line IV indicates a value of the electromagnetic torque when a is 52° and ⁇ is a variable angle;
• the line V indicates a value of the electromagnetic torque when a is 60° and ⁇ is a variable angle; and
• the line VI indicates a value of the electromagnetic torque when a is 64° and ⁇ is a variable angle. It may be seen from Fig. 4 that when ⁇ is around 50° and a is around 52°, the value of the electromagnetic torque of the permanent magnet motor reaches a desirable state.
• ⁇ may be 60°, and a may be selected from 52° to 64° according to actual requirement.
• the line VII indicates a value of the electromagnetic torque of the motor in the related art
• the line VIII indicates a value of the electromagnetic torque of the rotor 2 of the permanent magnet motor 100 when ⁇ is 60°.
• both of a distance from the outer surface of the first groove segment 2121 to the outer edge of the rotor core 21 and a distance from the outer surface of the second groove segment 2122 to the outer edge of the rotor core 21 are W2.
• the ratio of Wl to W2 ranges from 0.9 to 1.1
• the ratio of W3 to W2 ranges from 2.0 to 3.0.
• the fluctuation range of the electromagnetic torque of the permanent magnet motor according to embodiments of the present invention is smaller and the electromagnetic torque of the permanent magnet motor is greater, such that the overall performance of the permanent magnet motor reaches a desirable state.
• the performance improvement of the motor is caused by a plurality of factors, when the number of the stator teeth of the stator is large, the angular pitch of the stator teeth adjacent to each other is decreased, such that a may be greater than ⁇ so as to improve the overall performance of the motor to a higher level.
• the number of permanent magnets 202 is three, and the three permanent magnets 202 are received in three receiving recesses 2011 of a rotor core 201 respectively.
• Grooves 2012 respectively extend outward from two ends of each receiving recess 2011 and includes a first groove segment 20121 extending beyond a first surface 20111 of the receiving recess 2011 and a second groove segment 20122 extending beyond a second surface 20112 of the receiving recess 2011.
• the N poles of the permanent magnets 22 face towards an outer edge of the rotor core 201, and the S poles of the permanent magnets 22 face towards a center O of a central hole 20.
• a magnetic field of each permanent magnet 202 does not cross over other permanent magnets 202, i.e., the magnetic field of each permanent magnet 202 does not interfere with other permanent magnets 202.
• the S poles of the permanent magnets 202 may face towards the outer edge of the rotor core 201, and the N poles of the permanent magnets 202 may face towards the center O of the central hole 20.
• a central angle whose vertex is a center O of the central hole 20 and whose sides pass through the free ends (the second ends) of two second groove segments 20122 located on two ends of any one of the receiving recesses 2011 is a
• a central angle whose vertex is the center O of the central hole 20 and whose sides pass through a free end (a first end) of one first groove segment 20121 of one receiving recess 2011 and a free end (a first end) of one first segment groove 20121 of another receiving recess 2011 adjacent to the one first groove segment 20121 of the one receiving recess 2011 is ⁇
• a ratio of a to ⁇ ranges from 0.8 to 1.2.
• the permanent magnet motor according to embodiments of the present invention adopts less permanent magnet, but effectively improves the electromagnetic torque of the motor and reduces the electromagnetic torque fluctuation of the motor.
• a shape of the permanent magnet 22 may be a substantial U, correspondingly, a shape of the receiving recess also may be a substantial U.
• Other structures of the permanent magnet motor according to the third embodiment of the present invention are the same as those of the permanent magnet motor according to the first embodiment of the present invention, which are omitted herein.
• the permanent magnet includes a pair of sub-permanent magnets 22a arranged as a substantial V, and the same magnetic poles of the pair of sub-permanent magnets 22a face towards a similar direction, such that surfaces of the same magnetic poles of the pair of sub-permanent magnets 22a may be considered as a same surface.
• Other structures of the permanent magnet motor according to the fourth embodiment of the present invention are the same as those of the permanent magnet motor according to the first embodiment of the present invention, which are omitted herein.
• the permanent magnet motor according to embodiments of the present invention is not limited to a motor having a rotor disposed inside a stator.
• the permanent magnet motor is an external rotor motor
• a rotor 200 includes a rotor core 203 and permanent magnets 204 disposed in the rotor core 203.
• the rotor 200 has a central hole 205 configured to mount a stator (not shown) fitted with the rotor 200, such that the stator is disposed inside the rotor 200.
• a receiving recess 2031 configured to receive the permanent magnets 204 is provided with grooves 2032 on two ends thereof, and the groove 2032 has a first groove segment 20321 and a second groove segment 20322 which both have free ends extending beyond the N and S pole surfaces of the permanent magnets 204 respectively.
• a width of the first groove segment 20321 is greater than that of the second groove segment 20322.
• Other structures of the external rotor permanent magnet motor according to the embodiment of the present invention are the same as those of the permanent magnet motor according to the first embodiment of the present invention, which are omitted herein.

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• Engineering & Computer Science (AREA)
• Power Engineering (AREA)
• Permanent Field Magnets Of Synchronous Machinery (AREA)
• Iron Core Of Rotating Electric Machines (AREA)

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• 2013
  • 2013-02-01 CN CN201310042049.9A patent/CN103117611B/zh active Active
  • 2013-11-22 WO PCT/CN2013/087727 patent/WO2014117575A1/en active Application Filing

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