CN110120730B

CN110120730B - Outer rotor permanent magnet rotating motor

Info

Publication number: CN110120730B
Application number: CN201811510969.8A
Authority: CN
Inventors: 堀雅宽; 三好努
Original assignee: Hitachi Industrial Equipment Systems Co Ltd
Current assignee: Hitachi Industrial Equipment Systems Co Ltd
Priority date: 2018-02-05
Filing date: 2018-12-11
Publication date: 2021-02-12
Anticipated expiration: 2038-12-11
Also published as: CN110120730A; JP7027187B2; JP2019135890A

Abstract

The invention provides an outer rotor permanent magnet rotating motor which restrains cost and reduces loss generated by a magnet, wherein the outer rotor permanent magnet rotating motor is a rotor composed of a rotor iron core and a permanent magnet arranged on the inner diameter side of the rotor iron core; and a stator including a stator core disposed on an inner diameter side of the rotor with a gap therebetween and coils disposed in a plurality of slots formed in the stator core, wherein the rotor core has a gap at a position where the permanent magnet is disposed.

Description

Outer rotor permanent magnet rotating motor

Technical Field

The invention relates to an outer rotor rotating motor, in particular to an outer rotor permanent magnet rotating motor.

Background

The outer rotor permanent magnet rotating electrical machine has a structure in which a rotor having a permanent magnet mounted thereon is disposed on the outer peripheral side of a stator having a coil mounted thereon. Compared with an inward rotation type permanent magnet rotary motor, the outer rotor permanent magnet rotary motor has the following characteristics: since the radius of the rotor-stator gap (slit) is larger and the circumference of the 1 pole is longer because the rotor is located outside, a magnet having a large area as viewed from the slit can be arranged. This can achieve high output and miniaturization of the rotating electric machine.

However, the surface magnet type in which the magnet is arranged to face the slit has a problem that the magnet is easily affected by the harmonic magnetic flux of the slit and the eddy current loss of the magnet increases because the magnet is located in the vicinity of the slit. When the magnet temperature increases due to the eddy current loss of the magnet, the magnet may be thermally demagnetized, which may degrade the performance of the rotating electric machine.

For example, patent document 1 discloses a technique for reducing eddy current loss of a magnet. Patent document 1 discloses a permanent magnet type rotating electrical machine in which a plurality of permanent magnets corresponding to respective magnetic poles are arranged in a circumferential direction in a core of a rotor arranged on an inner circumferential side of a stator with a gap therebetween, wherein the permanent magnets are configured by using an assembly of a plurality of magnet pieces having different magnetic characteristics and having the same shape. According to this configuration, the eddy current loss of the magnet can be reduced by dividing the magnet.

Documents of the prior art

Patent document

Patent document 1: japanese patent laid-open No. 2014-33582

Disclosure of Invention

Problems to be solved by the invention

In patent document 1, since the magnets are divided into small pieces, the work of inserting the magnets and bonding the magnets is increased, and thus the cost may be increased. Therefore, it is desirable to suppress the cost without changing the structure of the permanent magnet in which the permanent magnet is arranged in divided fashion.

The invention aims to provide an outer rotor permanent magnet rotating motor which can restrain cost and reduce loss generated in a magnet.

Means for solving the problems

A preferred example of the present invention is an outer rotor permanent magnet rotating electrical machine including a rotor core and a permanent magnet disposed on an inner diameter side of the rotor core; and a stator including a stator core disposed on an inner diameter side of the rotor with a gap therebetween and coils disposed in a plurality of slots formed in the stator core, wherein the rotor core has a gap at a position where the permanent magnet is disposed.

Effects of the invention

According to the present invention, an outer rotor permanent magnet rotating electrical machine can be obtained in which the loss generated in the magnets is reduced while suppressing the cost.

Drawings

Fig. 1 is a view showing a radial configuration of an outer rotor permanent magnet rotating electrical machine according to embodiment 1.

Fig. 2 is a view showing a structure in a radial direction in which the vicinity of the groove in example 1 is enlarged.

Fig. 3 is a simulation diagram of the flow of harmonic magnetic flux of embodiment 1.

Fig. 4 is a diagram showing effects achieved by the groove of embodiment 1.

Fig. 5 is a view showing a structure in a radial direction in which the vicinity of the semicircular groove in example 1 is enlarged.

Fig. 6 is a view showing a structure in a radial direction in which the vicinity of the triangular groove of example 1 is enlarged.

Fig. 7 is a diagram showing a loss in the width of the groove in example 1.

Fig. 8 is a view showing a structure in a radial direction in which the vicinity of the gap in example 2 is enlarged.

Fig. 9 is a diagram showing a loss in position of the void with respect to example 2.

Fig. 10 is a diagram showing an axial configuration of an elevator hoisting machine using an outer rotor permanent magnet rotating machine according to embodiment 3.

Detailed Description

Hereinafter, an embodiment of an outer rotor permanent magnet rotating electrical machine will be described with reference to the drawings.

[ example 1]

Fig. 1 shows an embodiment 1 of an outer rotor permanent magnet rotary electric machine. Fig. 1 is a view showing a radial structure (a direction showing a diameter of a rotor) of a permanent magnet rotating electrical machine. The outer rotor permanent magnet rotating electrical machine 1 of the present embodiment includes a rotor 4 and a stator 7, the rotor 4 being composed of a rotor core 2 and a permanent magnet 3, the rotor core 2 and the permanent magnet 3 being formed in an annular shape around a rotation shaft (not shown), and the stator 7 being disposed with a predetermined gap on the inner diameter side of the rotor 4, and being composed of a stator core 5 and a coil 6, the stator being formed in an annular shape. Here, the permanent magnet 3 is preferably of a surface magnet type disposed on the surface of the rotor core 2. The inner diameter side refers to a direction in which the rotor or the like is located on a diameter thereof and faces a rotation axis direction of the rotor, and the opposite direction is referred to as an outer diameter side.

As a result, the permanent magnets 3 are disposed on the surface of the rotor core 2, thereby reducing the leakage flux when the flux is short-circuited in the rotor, increasing the effective flux, and increasing the output. The coil 6 is preferably mounted to the stator core 5 by concentrated winding. This shortens the length of the axially short portion of the coil 6, shortens the axial length of the outer rotor permanent magnet rotating electrical machine 1, and can achieve downsizing.

It is preferable that the portion (slot 8) of the stator core 5 where the coil 6 is disposed be an open slot. This facilitates insertion of the coil 6, and improves assemblability. Further, the vicinity of the gap (tooth tip) of the stator core 5 is shaped to protrude from the stator 7 toward the rotor 4. The tooth tips preferably have a radius of curvature smaller than the radius of the stator core 5. This can reduce the rate of change in magnetic resistance in the circumferential direction (indicating the circumferential direction of the rotor core 2 or the stator core 5), and can reduce torque ripple.

Here, a groove 9 as an open space portion having an opening on one side of the permanent magnet 3 is provided in the rotor core 2 at a position corresponding to the center in the width direction of the permanent magnet 3 (the circumferential direction of the inside of the rotor core 2). Fig. 2 shows an enlarged view of the vicinity of the groove 9 as an example of the clearance. The effect of the groove 9 is described using fig. 3. The arrows in fig. 3 indicate harmonic components of the magnetic flux. Normally, harmonic components of the magnetic flux are linked perpendicularly from the stator 7 to the permanent magnets 3, but by providing the slots 9, the slots 9 become reluctance, and harmonic components of the magnetic flux are linked to the magnets so as to be separated from each other in the slots 9.

This eliminates the component in the magnet width direction (circumferential direction of the rotor core 2) of the harmonic of the magnetic flux, reduces the harmonic component linked with the permanent magnet 3, and reduces the eddy current. Further, since the slot 9 becomes a magnetic resistance, the inductance is reduced, and thereby the motor power supply voltage at the time of driving can be reduced. In general, a permanent magnet rotating electrical machine is driven by an inverter, and there is an upper limit to the voltage at the time of driving, which becomes a restriction in design.

Therefore, by reducing the motor power supply voltage during driving, the degree of freedom in design can be increased, and the motor performance can be improved. In addition, the groove 9 can reduce the rate of change in the magnetic resistance in the circumferential direction of the gap between the rotor 4 and the stator 7, and can reduce torque ripple.

Next, the shapes of the grooves 9 are compared. Fig. 4 shows a comparison between the total loss (copper loss + iron loss + magnet eddy current loss) of the rotating electric machine and the voltage during driving when a trapezoidal, rectangular, or inverted trapezoidal groove shape is used. According to fig. 4, in the case where the groove 9 has a trapezoidal shape, the loss reduction effect and the voltage reduction effect are the greatest. Thus, the grooves 9 are preferably trapezoidal in shape. Further, the semicircular grooves 10 in fig. 5 and the triangular grooves 11 in fig. 6, which are nearly trapezoidal, can also obtain an effective effect.

Next, the sizes of the grooves 9 are compared. Fig. 7 shows the sum of losses with respect to the ratio of the widths of the permanent magnet 3 and the groove 9. According to fig. 7, the total loss is minimized in the vicinity of 0.25[ p.u. ] of the slot width/magnet width. In addition, when the groove width/magnet width > 0.40[ p.u. ], the total loss becomes significantly larger than the case where the groove 9 is not provided. Therefore, the groove width/magnet width is preferably 0.40[ p.u. ]. Further, the groove width/magnet width is preferably 0.10[ p.u ] or more.

Fig. 1 shows a 40-pole 48-slot outer rotor permanent magnet rotating machine, but the shape is not limited to this, and similar effects can be obtained with other slot combinations. Further, in the case where the outer rotor rotary electric machine has two rotations, the groove shape is preferably symmetrical about the central axis.

[ example 2]

Fig. 8 shows an outer rotor permanent magnet rotary electric machine 1 according to embodiment 2. In embodiment 1, the rotor core 2 is provided with the slots 9, but as shown in fig. 8, a closed space portion 12 may be provided in the rotor core 2 in the vicinity of the permanent magnets 3 as an example of a gap. When the slot 9 is provided, the contact area between the rotor core 2 and the permanent magnet 3 is reduced, and therefore, it may be difficult to fix the permanent magnet 3.

Further, the provision of the groove 9 may reduce the permeability (permeability) of the permanent magnet 3, thereby reducing the demagnetization resistance of the magnet. In the case where the closed space portion 12 is provided, problems regarding the strength and the permeance of these fixations become less. However, the closed space 12 may be more difficult to manufacture than the groove 9. However, when the rotor core 2, which is a steel plate, is formed by punching, no problem arises. A plurality of punched rotor cores 2 are stacked to produce a rotor core 2.

The positions of the closed space portions 12 are compared. Fig. 9 shows the sum of losses for the void positions. The gap position is a distance from the surface of the permanent magnet 3 on the rotor core 2 side to the surface on the inner diameter side of the closed space portion 12. According to FIG. 9, the loss is minimized in the vicinity of the gap positions 1.0 mm to 1.5 mm. Further, there is a possibility that the total loss becomes larger than that in the case where there is no gap if the gap position is more than 3.0[ mm ]. Thus, the position of the gap is preferably 3.0[ mm ] or less. The shape, size, and the like of the closed space 12 are preferably the same as those of the groove 9. Further, the air does not necessarily have to be filled in the gap, and a non-magnetic material such as resin may be used. The shape of the closed space 12 may be trapezoidal, rectangular, inverted trapezoidal, or semicircular, as in the shape of a groove.

[ example 3]

Fig. 10 shows a configuration example of embodiment 3 of an outer rotor permanent magnet rotating electrical machine according to an application example of an outer rotor rotating electrical machine elevator hoisting machine. Fig. 10 shows only 1/2 in an axial cross section, and hatching is drawn on the rotation portion. The rotor shaft 16 and the rotor core 2 shown in the lower part of fig. 10 are connected to the permanent magnets 3, and the rotor 4 including the rotor core 2 and the permanent magnets 3 rotates with respect to the stator 7 with a predetermined gap therebetween by the rotation of the rotor shaft. In fig. 10, a gap such as the groove 9 is omitted.

As shown in fig. 10, in the elevator hoisting machine, a sheave 14 for winding a wire rope 13 of the elevator hoisting machine and a brake 15 for mechanically stopping rotation are attached to an outer rotor permanent magnet rotating machine 1, and the wire rope connected to a car is wound up.

According to the present embodiment, since the outer rotor permanent magnet rotating electrical machine is used which is reduced in size by improving the cooling performance due to the above-described reduction in loss, the weight of the elevator hoisting machine can be reduced, and the cost for installation can be reduced. In addition, the torque ripple of the outer rotor permanent magnet rotating electric machine can be reduced, and therefore the riding experience of the elevator can be improved.

Description of reference numerals

1 … outer rotor permanent magnet rotating machine, 2 … rotor core, 3 … permanent magnet, 4 … rotor, 5 … stator core, 6 … coil, 7 … stator, 8 … groove, 9 … groove, space part closed by 12 …, 13 … steel wire rope, 14 … pulley, 15 … brake.

Claims

1. An outer rotor permanent magnet rotating electrical machine, comprising:

a rotor including a rotor core and a permanent magnet disposed on an inner diameter side of the rotor core; and

a stator having a stator core disposed on an inner diameter side of the rotor with a gap therebetween and coils disposed in a plurality of slots formed in the stator core,

the rotor core has a gap at a position where the permanent magnet is disposed,

the width of the gap is 40% or less with respect to the width of the permanent magnet.

2. An outer rotor permanent magnet rotary electric machine according to claim 1, wherein:

the gap is a groove disposed to face the permanent magnet.

3. An outer rotor permanent magnet rotary electric machine according to claim 1, wherein:

the distance between the gap and the permanent magnet is less than 3.0 mm.

4. An outer rotor permanent magnet rotary electric machine according to claim 1, wherein:

the gap is substantially trapezoidal in which the inner diameter side of the rotor core is a long side and the outer diameter side is a short side.

5. An outer rotor permanent magnet rotary electric machine according to claim 1, wherein:

the gap is substantially triangular with a base in the direction of the stator.

6. An outer rotor permanent magnet rotary electric machine according to claim 1, wherein:

the gap is a semicircular shape having a bottom side in the direction of the stator.

7. An outer rotor permanent magnet rotary electric machine according to claim 1, wherein:

the void is filled with a non-magnetic body.

8. An outer rotor permanent magnet rotary electric machine according to claim 1, wherein:

the permanent magnet is disposed at a position facing the gap of the rotor core.

9. An outer rotor permanent magnet rotary electric machine according to claim 1, wherein:

the rotor is connected with a rotating shaft, and the outer rotor permanent magnet rotating motor generates rotating force for winding a steel wire rope connected with an elevator car.