JP2006223052A - Permanent-magnet motor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problem in conventional permanent-magnet motors, permanent magnets are placed in the entire areas of magnet insertion holes for the enhancement of efficiency; since the permanent magnet is most expensive among the major materials of the motor, however, such a construction is required that the quantity of used permanent magnets is reduced as much as possible and high torque is generated, to obtain a permanent-magnet motor of low cost and yet high efficiency. <P>SOLUTION: A permanent-magnet motor is constructed of a rotor in which permanent magnets are arranged as alternately magnetized in north pole and south pole. The permanent-magnet motor is provided with magnet insertion holes that are of multilayer structure and a plurality of which are arranged per pole in the rotor core of the motor; and permanent magnets that are individually buried in the magnet insertion holes, and so disposed that a permanent magnet, shorter than the length of at least one magnet insertion hole, is biased to either side in the magnet insertion hole. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a structure of a rotor of a permanent magnet type motor in which permanent magnets are arranged inside the rotor, and more particularly to a rotor suitable for high efficiency.

  In a conventional rotor with permanent magnets, a plurality of sets of permanent magnets arranged at intervals of two or more layers per pole in the radial direction of the rotor are embedded in a rotor body made of a high-permeability material. The interval between the permanent magnets is set such that the interval on the end side located at least on the forward side in the rotation direction of the rotor is wider than the interval between the other portions.

  Since the interval between the permanent magnets is thus wide, the current flowing through the stator is shifted in phase so that the reluctance torque and magnet torque increase, and an alternating current having a frequency according to the rotor rotational speed is generated. (See, for example, Patent Document 1).

  In another conventional electric motor rotor, the permanent magnet is placed close to the q-axis so that the angle formed by the d-axis and the q-axis is less than 90 ° in electrical angle, and the permanent magnet and the flux barrier are paired. Thus, the pair of permanent magnets and the flux barrier are arranged in a square shape toward the center of the rotor core.

  Then, the current phase at which the magnet torque becomes maximum shifts toward the current phase at which the reluctance torque becomes maximum, and the maximum point of the magnet torque approaches the maximum point of the reluctance torque, so that the total torque is improved (for example, , See Patent Document 2).

  In another conventional permanent magnet type synchronous rotating electrical machine rotor, a permanent magnet that is a field is embedded in a rotor core in which thin disk-shaped electromagnetic steel sheets are laminated, and leakage flux is generated between each pole of the rotor core. This is a structure in which a rectangular permanent magnet insertion hole is provided obliquely at a predetermined inclination angle with respect to the circumferential direction and a magnetized permanent magnet is inserted between the holes. The reluctance torque can be increased by controlling the phase of the current, and the direction of the reluctance is generated, and when the rotation direction is determined, the start-up / shift is facilitated (for example, see Patent Document 3). .)

JP-A-8-336246 (page 3-4, FIG. 1) JP 2000-287393 A (page 3-4, FIG. 1-2) JP-A-8-33246 (page 3, FIG. 1)

  Although the conventional motors configured as described above have the effect of bringing the phase difference between the peak of the magnet torque and the peak of the reluctance torque closer, they cannot be said to be a sufficient structure in terms of both cost and performance efficiency. . For example, a conventional rotor with a permanent magnet has a high efficiency but a high cost because permanent magnets are arranged in the entire region of the magnet insertion hole. In addition, in other conventional motor rotors, it is necessary to configure a larger cross-sectional area of the flux barrier, so it is inevitable to make the permanent magnet small, resulting in a decrease in magnet torque and sufficient performance efficiency. There wasn't. In addition, another conventional permanent magnet type synchronous rotating electric machine rotor is similarly unsuitable for high torque and high efficiency due to insufficient permanent magnet amount.

  Of the magnetic steel sheets, windings, and permanent magnets that are the main materials of permanent magnet motors, permanent magnets are the most expensive, and the cost of permanent magnets in a permanent magnet motor is generally 30-50%. It accounts for a large proportion. Therefore, in order to obtain a magnet type motor that achieves both low cost and high efficiency, a structure that generates high torque while reducing the amount of permanent magnets used as much as possible is required.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to obtain a highly efficient permanent magnet type motor while minimizing the cost of the permanent magnet that occupies most of the cost of the motor.

  A permanent magnet type motor according to the present invention comprises a laminated iron core, a stator comprising slots arranged in the circumferential direction, teeth formed between adjacent slots, and coils accommodated in the slots, and teeth. In a permanent magnet type motor composed of a rotor having a permanent magnet in which N poles and S poles are alternately magnetized, opposed to the inner peripheral part of the rotor, per one pole inside the rotor core of the rotor A plurality of magnet insertion holes arranged in a multi-layer structure, and permanent magnets embedded in the magnet insertion holes, smaller in length than at least one magnet insertion hole, and biased toward one of the magnet insertion holes And.

  A permanent magnet type motor according to the present invention comprises a laminated iron core, a circumferentially arranged slot, teeth formed between adjacent slots, and a stator comprising a coil accommodated in the slot; In a permanent magnet type motor composed of a rotor having a permanent magnet in which N poles and S poles are alternately magnetized, facing the inner peripheral portion of the teeth, provided inside the rotor core of the rotor And a space extending in the circumferential direction of the rotor core end from both ends of the permanent magnet inserted into the magnet insertion hole, and the space in the magnet insertion hole and the outer periphery of the rotor core The size of the outer peripheral bridge portion provided between the two is configured to increase smoothly toward the magnetic pole center of the rotor.

  A permanent magnet type motor according to the present invention comprises a laminated iron core, a stator comprising slots arranged in the circumferential direction, teeth formed between adjacent slots, and coils accommodated in the slots, and teeth. In a permanent magnet type motor composed of a rotor having a permanent magnet in which N poles and S poles are alternately magnetized, opposed to the inner peripheral part of the rotor, per one pole inside the rotor core of the rotor A plurality of magnet insertion holes arranged in a multi-layer structure, and permanent magnets embedded in the magnet insertion holes and arranged in at least one magnet insertion hole that is smaller in length than the magnet insertion holes and biased to one of the magnet insertion holes Therefore, the combined torque can be reduced by reducing the amount of permanent magnets used, reducing the cost of the motor, and bringing the phase of the magnet torque and reluctance torque closer. It is improved and a highly efficient permanent magnet type motor can be realized.

  A permanent magnet type motor according to the present invention comprises a laminated iron core, a circumferentially arranged slot, teeth formed between adjacent slots, and a stator comprising a coil accommodated in the slot; In a permanent magnet type motor composed of a rotor having a permanent magnet in which N poles and S poles are alternately magnetized, facing the inner peripheral portion of the teeth, provided inside the rotor core of the rotor And a space extending in the circumferential direction of the rotor core end from both ends of the permanent magnet inserted into the magnet insertion hole, and the space in the magnet insertion hole and the outer periphery of the rotor core Since the dimension of the outer peripheral bridge portion provided between the two is configured so as to increase smoothly toward the magnetic pole center of the rotor, it is possible to suppress iron loss by smoothing the change in magnetic flux, Permanent amount of iron loss By focusing on reducing the amount of magnets used, a highly efficient permanent magnet motor with reduced costs can be obtained.

Embodiment 1 FIG.
1 is a cross-sectional view of a permanent magnet type motor according to Embodiment 1 of the present invention. In the figure, 1 is a cylindrical stator core provided with nine slots 2 extending in the axial direction on the inner circumferential surface arranged in the circumferential direction, and a thin electromagnetic core having a thickness of about 0.35 to 0.5 mm. It is configured by punching steel sheets one by one and stacking a predetermined number of sheets. A tooth portion 3 is formed between adjacent slots 2. The teeth portion 3 has a substantially parallel shape from the outer diameter side to the inner diameter side, and has an umbrella-like structure in which both sides expand in the circumferential direction as it becomes the tip portion on the inner diameter side.

  In addition, by providing a slot opening of about 0.5 to 4 mm between the tips of adjacent teeth 3, the magnetic flux generated from the stator 5 and the rotor is short-circuited between adjacent teeth 3. This prevents a decrease in output. Reference numeral 4 denotes a concentrated winding coil in which a copper wire is directly wound around the tooth portion 3, and a three-phase Y connection or a three-phase Δ connection is applied. Reference numeral 5 denotes a stator having a stator core 1 and a coil 4.

  Between the stator 5 and the rotor 9 which is arranged on the axis of the stator 5 and is fixed to the rotor shaft 6 which is rotatable with respect to the stator 5, is about 0.3 mm to 1 mm. An air gap 10 is provided and is configured to be rotatable about the rotor shaft 6. The rotor core 7 is configured by punching and stacking magnetic steel sheets one by one in the same manner as the stator, and is held by the rivets 11 and the like so that the magnetic steel sheets do not fall apart.

  A magnet insertion hole 15 is disposed inside the rotor core 7. Two magnet insertion holes 15 are provided in parallel in the same pole and formed in a two-layer structure. The magnet insertion holes 15a are provided on the outer peripheral side of the rotor core 7 and provided on the inner peripheral portion of the magnet insertion hole 15a. It is comprised by the magnet insertion hole 15b from which length differs. In FIG. 1, the magnet insertion hole 15b provided in the inner peripheral part is provided as a longer insertion hole than the magnet insertion hole 15a provided in the outer peripheral side. Each magnet insertion hole 15a, 15b has a structure in which sintered rare earth permanent magnets 8a, 8b mainly composed of flat neodymium, iron, and boron are embedded.

  Of the magnet insertion holes 15 formed in a two-layer structure in the radial direction around the rotor shaft 6, the circumferential length of the permanent magnet 8 a embedded in the magnet insertion hole 15 a provided on the outer peripheral side of the rotor core 7. Is made smaller than 2/3 of the circumferential length of the magnet insertion hole 15a, and the permanent magnet 8a is biased toward the rotor rotation direction side of the magnet insertion hole 15a. An inter-electrode bridge portion 12 is provided between the magnet insertion holes 15 adjacent in the circumferential direction of the rotor, and the outer peripheral bridge portion 13 provided between both end portions of the magnet insertion hole 15a and the outer periphery of the rotor core. To form a one-piece structure.

  As described above, the circumferential length of the permanent magnet 8a embedded in the outer peripheral side of the rotor core 7 is made smaller than the provided magnet insertion hole 15a, and the permanent magnet is biased toward the rotational direction of the rotor. 2, the phase of the peak of the magnet torque (shown by the dotted line in the figure) and the peak of the reluctance torque (shown by the one-dot chain line in the figure) are brought close to about 35 degrees in electrical angle, as shown in FIG. Therefore, the combined torque (indicated by a solid line in the figure), which is the sum of the magnet torque and the reluctance torque, can be improved, and a permanent magnet motor with high efficiency and reduced cost can be realized.

  Although the case where the stator windings are concentrated windings has been described as an example, the same effect can be obtained even if the stator windings are distributed windings. In addition, although the sintered rare earth magnet has been described as an example of the material of the permanent magnet 8, the same effect can be obtained with any other permanent magnet. In addition, with regard to the orientation direction of the permanent magnet, an effect can be obtained in any orientation direction. In particular, the effect of shifting the phase of the peak of the magnet torque to the phase side by tilting the orientation direction to the rotation direction side. There is an effect that further increases the efficiency.

  In addition, the magnet insertion holes formed in the two-layer structure described above and the permanent magnet 8a on the outer peripheral side are arranged so as to be biased toward the rotation direction, and the shapes of the magnet insertion holes 15a and 15b provided inside the rotor core are shown in FIG. As shown in FIG. 4, an asymmetrical structure in which only the end portion on the counter-rotation direction side of the magnet insertion hole 15b provided in the inner peripheral portion is bent toward the outer peripheral side of the rotor core, or on the outer peripheral side as shown in FIG. An asymmetrical structure in which the interval between the magnet insertion hole 15a provided and the magnet insertion hole 15b provided in the inner peripheral portion is widened in the rotation direction side, and further, the shape of the magnet insertion hole 15 as shown in FIG. In the shape of an asymmetrical convex shape, that is, the center of the magnetic pole is shifted in the rotational direction from the center of the dimension of the pole (1/2 * A line in FIG. 5). The phase of the reluctance torque peak is shifted to the delayed phase side. That effect there is, the phase difference between the peak of the magnet torque and the reluctance torque can be brought close to around 25 degrees, it is possible to obtain a more efficient permanent magnet motor.

  Furthermore, as shown in FIG. 6, the permanent magnet 8a embedded in the magnet insertion hole 15a provided on the outer peripheral side of the rotor core 7 is a first permanent magnet 8a1 on the rotation direction side and a second permanent magnet on the counter rotation direction side. 8a2 is divided and arranged so that the residual magnetic flux density of the second permanent magnet 8a2 arranged on the counter-rotation direction side is smaller than the residual magnetic flux density of the first permanent magnet 8a1 arranged on the rotation direction side. The magnet torque can be improved, the motor can be increased in torque and efficiency, and the cost can be increased by using the relatively inexpensive second permanent magnet 8a2 having a small residual magnetic flux density on the counter-rotating direction side. Can be suppressed.

Embodiment 2. FIG.
7 is a sectional view of the rotor of the permanent magnet type motor according to the second embodiment of the present invention, and FIG. 8 is a partially enlarged view of the rotor pole portion of FIG. Here, since the stator side is the same as the stator described in the first embodiment, the description thereof will be omitted, and the configuration of the rotor will be described below.
In the figure, reference numeral 7 denotes a rotor core. Inside the rotor core 7, a magnet insertion hole 15 is arranged, and a permanent magnet 8 in which N poles and S poles are alternately magnetized is embedded. ing. An inter-electrode bridge portion 12 is provided between adjacent magnet insertion holes 15, and is combined with an outer peripheral bridge portion 13 provided at both ends of the magnet insertion hole 15 to form an integral structure.

  The shape of both end portions of the magnet insertion hole 15 has a curved space portion 14 that is smoothly curved along the outer periphery of the rotor core from the end portion of the permanent magnet inserted therein. The outer peripheral bridge portion 13 provided between the curved space portion 14 at both ends of the rotor and the outer periphery of the rotor core is configured so that the dimension thereof increases smoothly as it goes toward the magnetic pole center of the rotor. In FIG. 8 showing an enlarged view of the main part of this example, the dimension of the outer bridge 13 facing the outermost end of the magnet insertion hole is W1, and the dimension of the outer bridge 13 facing the end of the curved space is W2. In this case, W2 is set to 2 mm with respect to W1 = 0.5 mm.

  As described above, by configuring the rotor of the permanent magnet type motor, the change in magnetic flux can be smoothed in a sine wave shape, and iron loss can be suppressed. Further, the amount of iron loss suppressed can be directed to reducing the amount of permanent magnets used, and a highly efficient permanent magnet type motor can be obtained while the motor cost is suppressed as much as possible.

  7 and 8, the cross-sectional shape of the magnet insertion hole excluding the curved space portion 14 is configured as a rectangle. However, the shape is not limited to this shape. For example, the magnet insertion hole protrudes toward the rotor shaft side as shown in FIG. 9. The same effect can be obtained with any shape such as a circular arc shape or a V-shape projecting toward the rotor shaft as shown in FIG. In this embodiment, the case where the stator windings are concentrated windings has been described as an example. However, the same effect can be obtained even if the stator windings are distributed windings. In addition, although a rare earth magnet has been described as an example of the permanent magnet 8, the same effect can be obtained with any other permanent magnet. Further, it goes without saying that the same effect can be obtained with any orientation such as parallel orientation and radial orientation in the orientation direction of the permanent magnet.

Embodiment 3 FIG.
FIG. 11 is a cross-sectional view of the rotor of the permanent magnet type motor according to Embodiment 3 of the present invention. Two magnet insertion holes 15 arranged in the rotor core 7 are provided in parallel in the same pole and formed in a two-layer structure. A magnet insertion hole 15a provided on the outer periphery side of the rotor core, and this magnet It is comprised by the magnet insertion hole 15b provided in the inner peripheral part of the insertion hole 15a. In each of the magnet insertion holes 15a and 15b, flat sintered rare earth permanent magnets 8a and 8b mainly composed of neodymium, iron, and boron magnetized so that N poles and S poles are alternately arranged. The structure is embedded.

  Between the adjacent magnet insertion holes 15a and 15b, an inter-electrode bridge portion 12 is provided, which is coupled to an outer peripheral bridge portion 13 provided between both ends of the magnet insertion hole 15a and the outer periphery of the rotor core. It has an integral structure. The shape of both ends of the magnet insertion holes 15a and 15b adjacent to the outer peripheral portion of the rotor core 7 and the interpolar portion of the N pole and the S pole is smoothly along the outer periphery of the rotor core. A curved space portion 14 is provided, and the dimensions of the outer peripheral bridge portion 13 provided between the curved space portions 14 at both ends of the magnet insertion hole 15 and the outer periphery of the rotor core are increased toward the magnetic pole center of the rotor. It is configured to increase smoothly. Specifically, when the dimension of the outer peripheral bridge portion 13 facing the outermost end portion of the magnet insertion hole is W1, and the dimension of the outer peripheral bridge portion 13 facing the end portion of the curved portion is W2, the dimension of W2 is set to W1. It is comprised so that it may become 1.5 times or more.

  By configuring the rotor of the permanent magnet type motor as described above, the change in magnetic flux can be smoothed, the iron loss can be suppressed, and the combined torque can be reduced by bringing the phase of the magnet torque and the reluctance torque closer. It is improved and a highly efficient permanent magnet type motor can be realized.

  In this embodiment, the cross-sectional shape of the magnet insertion hole excluding the curved space portion 14 is configured to be rectangular. However, the present invention is not limited to this shape, and as shown in FIG. A shape in which curved space portions are provided at both ends of the arc-shaped magnet insertion hole 15b that is convex, or curved at both ends of the V-shaped magnet insertion hole 15b that is convex on the axis side of the rotor as shown in FIG. The same effect can be obtained with any shape such as a shape provided with a space, or a combination of an arc shape and a rectangular shape, a combination of a V shape and a rectangular shape, and a combination of an asymmetric shape although not shown. be able to.

  In the present embodiment, the case where the stator winding is concentrated winding has been described as an example. However, the same effect can be obtained even if the stator winding is distributed winding. Moreover, although the rare earth magnet was demonstrated to the example as the permanent magnet 8, the same effect is acquired even if it is what kind of other permanent magnet. Needless to say, the same effect can be obtained with respect to the orientation direction of the permanent magnets in any orientation direction such as parallel orientation and radial orientation.

It is sectional drawing of the permanent magnet type motor which concerns on Embodiment 1 of this invention. It is a torque characteristic figure with respect to the phase angle of the permanent magnet type motor which concerns on Embodiment 1 of this invention. It is sectional drawing of the rotor which concerns on Embodiment 1 of this invention. It is sectional drawing of the rotor which concerns on Embodiment 1 of this invention. It is sectional drawing of the rotor which concerns on Embodiment 1 of this invention. It is sectional drawing of the rotor which concerns on Embodiment 1 of this invention. It is sectional drawing of the rotor of the permanent magnet type motor which concerns on Embodiment 2 of this invention. It is a principal part enlarged view of the rotor cross section of FIG. It is sectional drawing of the other rotor which concerns on Embodiment 2 of this invention. It is sectional drawing of the further another rotor which concerns on Embodiment 2 of this invention. It is a cross-sectional surface of the rotor of the permanent magnet type motor which concerns on Embodiment 3 of this invention. It is sectional drawing of the other rotor which concerns on Embodiment 3 of this invention. It is sectional drawing of the further another rotor which concerns on Embodiment 3 of this invention.

Explanation of symbols

  1 stator core, 2 slots, 3 teeth, 4 coils, 5 stator, 6 rotor shaft, 7 rotor core, 8 permanent magnet, 9 rotor, 10 air gap, 11 rivets, 12 interpole bridge, 13 outer circumference Bridge part, 14 curved space part, 15 magnet insertion hole.

Claims (11)

A stator composed of a laminated iron core, arranged in the circumferential direction, teeth formed between adjacent slots, a coil housed in the slots, and a gap in the inner periphery of the teeth In a permanent magnet type motor composed of a rotor in which a permanent magnet with N and S poles alternately magnetized is arranged, a plurality of per poles are arranged inside the rotor core of the rotor to form a multilayer structure. A magnet insertion hole; and a permanent magnet embedded in each of the magnet insertion holes, and disposed in at least one of the magnet insertion holes, the permanent magnet being biased toward one of the magnet insertion holes. A permanent magnet type motor characterized by that. 2. The permanent magnet type motor according to claim 1, wherein the permanent magnet is arranged so as to be biased toward the rotation direction of the magnet insertion hole. The permanent magnet type motor according to claim 1 or 2, wherein at least one of the multilayer magnet insertion holes has an asymmetric shape. 4. The permanent magnet type motor according to claim 3, wherein the asymmetric shape is such that an end of the magnet insertion hole on the side opposite to the rotation direction is bent toward the outer peripheral side of the rotor. The permanent magnet type motor according to claim 3 or 4, wherein a plurality of magnet insertion holes arranged in a single pole and having a multi-layer structure are widened in the direction of rotation. The permanent magnet type motor according to any one of claims 1 to 5, wherein the magnet insertion hole has a substantially V-shape that protrudes toward the rotor shaft. A stator composed of a laminated iron core, arranged in the circumferential direction, teeth formed between adjacent slots, a coil housed in the slots, and a gap in the inner periphery of the teeth In a permanent magnet type motor composed of a rotor in which a permanent magnet with N and S poles alternately magnetized is arranged, a plurality of per poles are arranged inside the rotor core of the rotor to form a multilayer structure. A first permanent magnet and a second permanent magnet which are respectively embedded in the magnet insertion hole and divided into the rotation direction side and the counter-rotation direction side of at least one of the magnet insertion holes; The permanent magnet is configured such that the residual magnetic flux density of the second permanent magnet arranged on the counter-rotating direction side is smaller than the residual magnetic flux density of the first permanent magnet arranged on the rotating direction side. Magnet type motor. A stator composed of a laminated iron core, arranged in the circumferential direction, teeth formed between adjacent slots, a coil housed in the slots, and a gap in the inner periphery of the teeth In a permanent magnet type motor comprising a rotor having permanent magnets alternately magnetized with N and S poles, a magnet insertion hole provided in the rotor core of the rotor, and the magnet insertion An outer peripheral bridge provided between the space in the magnet insertion hole and the outer periphery of the rotor core, and a space extending in the circumferential direction of the end of the rotor core from both ends of the permanent magnet to be inserted into the hole A permanent magnet type motor characterized in that the size of the part increases smoothly toward the magnetic pole center of the rotor. 9. The permanent magnet motor according to claim 8, wherein a region of the magnet insertion hole facing the outer peripheral bridge portion of the rotor core is a non-magnetic portion, and a permanent magnet is disposed in a region other than the non-magnetic portion. The permanent magnet type motor according to claim 8 or 9, wherein a plurality of the magnet insertion holes are arranged per pole inside the rotor core of the rotor to form a multilayer structure. The permanent magnet type motor according to any one of claims 8 to 10, wherein a shape of the magnet insertion hole is an arc shape or a substantially V shape that protrudes toward the axis of the rotor.

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