JPH10290542A - Motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make gentle the variation of reluctance torque incident to rotation of a rotor by constructing the core part interposed between adjacent magnets of each pole of the rotor wider than the opening of slot. SOLUTION: At each pole of a rotor of four pole structure, a core part 12a forming the passage of q-axis flux is interposed between a shaft side magnet 3a and a counter-shaft side magnet 3b. The width W1 at the core part 12a between magnets in same pole is set wider than the width N2 of a slot opening 9a interposed between the tip parts at the tooth part 7 of a stator core 6a. Since the core part 12a between magnets is shifted to the rotational direction with respect to the tooth part, the rotor generates reluctance torque reversely to the rotational direction through action of magnetic attraction caused by the flux. But since the core part 12a is wide, the reluctance torque in the reverse direction is reduced and eventually canceled by the reluctance torque in the rotational direction.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a synchronous motor having a permanent magnet field represented by a motor for driving a compressor of a refrigerator or an air conditioner, and more particularly, to a synchronous motor having a magnet embedded inside a core of a rotor. The present invention relates to an electric motor having a so-called embedded magnet structure (IPM) rotor.

[0002]

2. Description of the Related Art As the above-mentioned electric motor, the electric motor having the configuration shown in FIG. 7 is known, and is disclosed in, for example, the article number 306 of the 1995 IEEJ National Conference on Industrial Applications Division Annual Conference. The motor of FIG. 7 shows a cross section perpendicular to the rotating shaft 4, which is fitted into a shaft hole provided at the center of a cylindrical rotor core 2 b to support the rotor 1. The rotor core 2b is provided with a plurality of magnet accommodation holes parallel to the shaft 4, and the magnets 3e and 3f are inserted into the accommodation holes by, for example, press fitting.

The magnets 3e and 3f have a substantially C-shape in the cross section shown in the figure, and are embedded in the iron core 2b with the convex side facing the shaft 4. Each pole forming the field is a shaft-side magnet 3
One pole is formed by the double magnet e and the anti-axis side magnet 3f, and the illustrated example shows a 4-pole field configuration.

The rotor 1 has a predetermined air gap 11.
And a stator 5 and a permanent magnet type synchronous motor. The stator 5 has a stator core 6b having an outer peripheral portion fixed to and supported by a casing. An inner peripheral portion of the stator core 6b has a plurality of teeth 7 formed between the teeth 7. A slot 8 having an opening 9b toward the air gap 11 is provided, and the slot 8 is provided with a winding 10 wound around an insulating material, for example, in a three-phase four-pole structure. Then, the rotor 1 rotates by energizing the winding 10 of the stator 5 via the inverter.

[0005] In the motor configured as described above, the relationship between the q-axis inductance Lq and the d-axis inductance Ld is characterized by a so-called reverse saliency in which Lq> Ld. Control driving is performed to use both of the torques. Double magnet 3 as shown in FIG.
In the case of a motor in which the magnetic field of each pole is constituted by e and 3f,
Iron core portion 12b between the shaft-side magnet 3e and the non-axis-side magnet 3f
Is present, this portion serves as a path for the q-axis magnetic flux, and the q-axis inductance Lq can be increased. For this reason, the structure is effective when the salient pole ratio Lq / Ld is increased to more actively utilize the reluctance torque.

[0006]

In the case of the conventional electric motor as shown in FIG. 7, special consideration is given to the width of the iron core portion 12b interposed between the shaft-side magnet 3e and the non-axis-side magnet 3f. Is not performed, and the magnets 3e, 3f
In general, the width is set to be very narrow for the sake of designing the demagnetization proof strength by making the width as large as possible. In addition, the slot opening 9b of the stator core 6b is set to have a width dimension emphasizing manufacturability since the winding 10 is inserted through this portion.

The inventors of the present invention have analyzed the problem of vibration and noise of this type of electric motor, and have found that the iron core portion 1 between the rotor magnets has been analyzed.
It has been found that the relationship between 2b and the slot opening 9b of the stator has a great effect. Hereinafter, this phenomenon will be described with reference to FIGS.

When the rotor core 2b and the stator core 6b are in a positional relationship as shown in FIG. 8, among the stator magnetic fluxes generated by energizing the stator winding, the magnets 3e and 3f between the adjacent magnets 3e and 3f of the rotor core 2b. The magnetic flux flowing into and out of the iron core portion 12b of
A magnetic path as shown by 14c is formed. That is, the rotor core 2b enters the rotor core 2b via the air gap 11 from the tooth portion 7c in the N pole of the stator core 6b, and the core portion 12b between the magnets.
Through the air gap 11 and again through the stator core 6
It is formed so as to return to the tooth portion in the S pole of b. Although the illustrated magnetic flux 14c is an example of the magnetic flux flowing into the rotor core 2b, the flow path is the same even in the case of the outgoing magnetic flux.

Next, when the rotor rotates in the direction indicated by arrow 15, the positional relationship between rotor core 2b and stator core 6b is as shown in FIG. In this state, since the core portion 12b between the magnets faces the slot opening 9b, the magnetic resistance is large, so that almost no magnetic flux flows into the core portion 12b. And then, FIG.
When the rotor rotates to the position shown in FIG. 7, the magnetic flux 14d flows into the iron core portion 12b from the adjacent tooth portion 7d in the same N pole.

In the vicinity of the state shown in FIG. 8, since the iron core portion 12b between the magnets is deviated in the rotational direction with respect to the tooth portion 7c, the rotor is rotated in the rotational direction by the action of magnetic attraction due to the presence of the magnetic flux 14c. And a reluctance torque in the opposite direction is generated. In the vicinity of the state shown in FIG. 9, since the magnetic flux flowing into the iron core portion 12b is interrupted once, no reluctance torque is generated in this portion. In the vicinity of the state of FIG. 10, since the iron core portion 12b is biased in the opposite direction of the rotation direction with respect to the tooth portion 7d, the rotor is rotated in the rotation direction by the action of the magnetic attraction force due to the presence of the magnetic flux 14d. Of reluctance torque.

Due to such a pulsating reluctance torque component, the vibration and noise accompanying the operation of the electric motor are extremely large, and a rotor having a magnet whose convex side is directed to the rotation axis is embedded in the iron core in multiple layers. This has been a major problem in motors having

[0012]

SUMMARY OF THE INVENTION According to the present invention, there is provided a magnet having a convex surface on one side and a concave surface on the other side. An electric motor comprising: a rotor configured to be multiple-embedded to the side; and a stator having windings mounted on a stator core having a plurality of slots opened toward the rotor side, characterized by the following configuration. And

According to a first aspect of the present invention, the width of an iron core portion interposed between adjacent magnets in each pole of the rotor is made larger than the width of an opening of a slot.
According to a second aspect of the present invention, a width of an iron core portion interposed between magnets adjacent to each other with a pole portion of the rotor therebetween is narrow enough to be sufficiently saturated by a magnetic flux of the magnet.

[0014]

According to the first aspect of the present invention, the magnetic flux flowing into and out of the iron core between the magnets at the rotor poles through the teeth of the stator is opposed to the tooth between the magnets. The change in reluctance torque associated with the rotation of the rotor is gradual without interruption at the transition.

In the second aspect of the present invention, the amount of magnetic flux flowing into and out of the iron core portion between the magnets of the rotor pole portion through the teeth of the stator is reduced, and the magnetic flux is opposed to the iron core portion of the pole gap portion. The change in the reluctance torque generated when the tooth portion changes is small.

[0016]

FIG. 1 is a plan sectional view of an electric motor according to an embodiment of the present invention, showing a section perpendicular to a rotating shaft 4. FIG. The rotor core 2a and the stator core 6a are formed by punching thin iron plates and laminating a large number of them. The uneven portions formed by the cut-and-raised projections provided on each of the thin iron plates are fitted to each other in the axial direction. Fixed and configured. A shaft 4 is fitted into the center of the rotor core 2a, and magnets 3a and 3b are inserted into a plurality of receiving holes provided in parallel with the shaft 4 by, for example, press fitting.

The magnets 3a and 3b are composed of anisotropic ferrite magnets or the like, and the magnets 3a and 3b are formed as double magnets with the convex side of the substantially C-shaped cross section facing the axis 4. Thus, the illustrated example illustrates the rotor 1 having a four-pole field configuration. The magnet receiving holes of the rotor core 2a and the magnets 3a and 3b do not necessarily have to be similar in shape. convenient.

The stator 5 opposed to the rotor 1 via the air gap 11 has a winding 10 wound around a plurality of slots 8 of a stator core 6a, for example, in a three-phase four-pole structure. The winding 10 is inserted into the iron core through the slot opening 9a. Therefore, the width of the slot opening 9a is set to a magnetically appropriate range and a size suitable for the winding insertion device. I have.

FIG. 2 is an enlarged view of a main part of the electric motor shown in FIG. In each pole of the rotor having a four-pole structure, an iron core portion 12a that forms a q-axis magnetic flux path is interposed between the shaft-side magnet 3a and the anti-axis-side magnet 3b. The width W1 of the iron core portion 12a between the magnets within the same pole is configured to be larger than the width W2 of the slot opening 9a interposed between the tips of the teeth 7 of the stator core 6a. The operation described in detail in FIGS. 3 to 5 occurs with the operation of the electric motor having this configuration.

First, when the rotor core 2a and the stator core 6a are in a positional relationship as shown in FIG. 3, magnets 3a, 3a, The magnetic flux flowing into and out of the iron core portion 12a between 3b forms a magnetic path as shown by 14a. That is,
Air gap 1 from tooth 7a in the N pole of stator core 6a
1, the rotor core 2a enters the rotor core 2a, flows through the iron core portion 12a between the magnets, and returns to the teeth in the S pole of the stator core 6a again via the air gap 11.

In the vicinity of the state shown in FIG. 3, since the iron core portion 12a between the magnets is deviated in the direction of rotation 15 with respect to the tooth portion 7a, the action of the magnetic attraction force due to the presence of the magnetic flux 14a causes the rotor to rotate. Causes a reluctance torque in the direction opposite to the rotation direction. But iron core 12a
Is large, the value of the reluctance torque in the opposite direction is small. Soon, a magnetic path is formed from the adjacent tooth portion 7b shown by 14b in FIG. 4, and the reluctance torque in the opposite direction is offset by the reluctance torque in the rotational direction.

When the rotor rotates in the direction of arrow 15 and the positional relationship between the rotor core 2a and the stator core 6a is close to that shown in FIG. 4, the tooth portions 7a and 7b are applied to the iron core portion 12a.
The magnetic fluxes 14a and 14b from both of the above flow smoothly, so that both the reluctance torques in the reverse rotation direction and the rotation direction are completely cancelled.

Next, when the rotor rotates to the position shown in FIG. 5, the magnetic flux 1 from the tooth portion 7a flowing into the iron core portion 12a.
4a gradually decreases, but the reluctance torque in the rotational direction due to the magnetic flux 14b from the inter-tooth portion 7b continues to be cancelled. Therefore, the state rapidly changes to the state in FIG. As a result, during the transition from the tooth portions 7a to 7b facing the iron core portion 12a, the magnetic paths of both the magnetic fluxes 14a and 14b are not interrupted, and the change in reluctance torque accompanying rotation of the rotor is moderate. Becomes As a result, vibration and noise of the electric motor caused by the pulsation of the reluctance torque component are greatly reduced.

As described above, since the magnetic flux from the stator flowing into and out of the iron core portion 12a is not interrupted at all times, the demagnetizing force applied to the magnets 3a and 3b is reduced. As a result, a rotor having excellent demagnetization resistance can be formed, and the cost can be reduced by reducing the thickness of the magnets as necessary.

Next, a second embodiment of the present invention will be described. Conventional example Vibration of the motor caused by the relationship between the core portion 12b and the slot opening 9b between the magnets 3e and 3f in the same pole described in FIGS.
The problem of noise can also be caused by the relationship between the iron core portion 13b and the slot opening 9b between the magnets 3e adjacent to each other with the rotor poles interposed therebetween by the same principle.

Therefore, in the embodiment shown in FIG. 2, if the width W3 of the iron core portion 13a between the magnets 3a in the gap between the poles is made larger than the width W2 of the slot opening 9a as in the case of the iron core portion 12a, vibration and vibration can be prevented. Effective for eliminating noise. However, the radius of the arc of the magnets 3a and 3b becomes small, the amount of magnetic flux by the magnet decreases, the main magnetic flux torque is greatly reduced more than the increase in reluctance torque, and the combined torque of these decreases. It is not a good idea to get it.

Therefore, in the present invention, as shown in FIG. 2, the width W3 of the core portion 13a between the magnets 3a, 3a in the pole portion is such that this portion is sufficiently saturated by the magnetic flux of the magnets 3a, 3b. It is configured to be narrow. With this configuration, the amount of magnetic flux flowing into and out of the iron core portion 13a between the magnets of the rotor pole portion via the teeth 7 of the stator is reduced, and the transition of the tooth portion 7 facing the iron core portion 13a is reduced. The pulsation of the reluctance torque generated at this time is small. As a specific example, the outer diameter of the rotor core 2a is about φ55 mm, the magnets 3a and 3b have a residual magnetic flux density of about 0.43T, and the number of poles of the field is 4
In a motor constituted by poles, a desired effect can be obtained by reducing the width W3 of the iron core portion 13a to about 1.0 mm.

When the width W1 of the iron core portion 12a is narrow enough to saturate the same as the iron core portion 13a, the magnet 3a flowing into and out of the stator via the iron core portion 12a is provided. The magnetic flux of the difference between the magnetic flux of the magnet 3b and the magnet 3b is generally undesirable because the amount of inflow and outflow is drastically reduced due to magnetic saturation, the main magnetic flux torque is reduced, and the effect of the multiple magnet structure is lost.

FIG. 6 shows another embodiment of the rotor according to the present invention, which is constructed by inserting magnets 3c and 3d into a substantially V-shaped accommodation hole of a rotor core 2c. In the case of such a V-shaped magnet, two V-shaped magnets are often combined to form one V-shape. An iron core portion 12c that forms a path for q-axis magnetic flux is interposed between the shaft-side magnet 3c and the anti-axis-side magnet 3d, and the width of the iron core portion 12c is the same as that of the motor shown in FIG. Is larger than the width of the slot opening.

When the accommodating hole of the rotor core 2c for accommodating the magnet 3c is formed in a simple V shape, the magnet 3c in the gap between the poles can be formed.
Since the width of the iron core portion 13c between the adjacent magnets c cannot be made sufficiently small, a notch 16 that forms a hole as shown in the figure is provided on the gap between the housing holes of the magnet 3c, and the outer peripheral portion of the rotor iron core 2c is formed. The width of the iron core portion 13c is narrowed only in the vicinity, and this portion is configured to be sufficiently saturated by the magnetic fluxes of the magnets 3c and 3d.

In the above embodiment, the magnets are arranged in a double arrangement for each pole of the rotor. However, the present invention is not limited to this, and the present invention can be applied to any number of rotors. . Also, an example is shown in which the first invention according to claim 1 and the second invention according to claim 2 are applied to the same electric motor. However, these first invention and second invention are each independently used. Good effects can be expected even when applied.

Further, in the embodiment, description has been made mainly of an example in which the width of the iron core portion between the magnets of the rotor is changed. However, the width dimension of the slot opening of the stator iron core is also appropriately determined within the scope of the present invention. Of course, it can be adjusted. still,
Usually, 12 or 24 slots are used in this type of motor, but the present invention does not particularly limit the range of the number of slots of the stator core.

In the embodiment of FIG. 2, the widths W1 and W3 of the iron core portions 12a and 13a of the rotor, respectively.
Represents a dimension mainly in the vicinity of the outer peripheral portion of the rotor core 2a. Usually, a cut portion such as a C-chamfer or an R-chamfer is appropriately provided in a corner portion of a housing hole of a magnet or a rotor core for housing the magnet, and various gaps exist between the magnet and the housing hole. In some cases, however, in the embodiment shown in FIG.

In particular, in the shape of the receiving hole, the rotor core 2
When the cut portion in the vicinity of the outer peripheral portion of “a” is large, the iron core portion is increased by that amount, and its influence is appropriately considered when setting the width dimensions W1 and W3. Since the present invention focuses on the exchange of magnetic flux between the rotor core and the stator core, the emphasis is placed on the shape of the accommodation hole of the rotor core that accommodates this rather than the shape of the magnet.

Further, when attention is paid to the shape of the iron core, the present invention can be applied not only to a motor having a magnet embedded therein but also to a multi-flux barrier type synchronous reluctance motor. In this case, the magnet in the embodiment may be removed to form a hole, or a non-conductive non-magnetic material may be embedded instead of the magnet. This type of electric motor is described, for example, in the paper number 1152 of the 1997 IEEJ National Convention.

[0036]

According to the present invention, the change in reluctance torque between the iron core portion between the magnets of the rotor core and the tooth portion of the stator iron core facing the magnet portion is caused by the rotation of the rotor. Since it is moderate, vibration and noise of the electric motor can be significantly reduced.

[Brief description of the drawings]

FIG. 1 is a sectional plan view of an electric motor showing an embodiment of the present invention.

FIG. 2 is an enlarged view for explaining a main part of FIG. 1;

FIG. 3 is an enlarged explanatory view of a main part showing a flow of a magnetic flux in the electric motor of FIG. 1;

FIG. 4 is an enlarged explanatory view of a main part showing a flow of a magnetic flux in the electric motor of FIG. 1;

FIG. 5 is an enlarged explanatory view of a main part showing a flow of a magnetic flux in the electric motor of FIG. 1;

FIG. 6 is a cross-sectional plan view showing another embodiment of the rotor according to the present invention.

FIG. 7 is a plan sectional view of a motor showing a conventional example.

FIG. 8 is an enlarged explanatory view of a main part showing a flow of magnetic flux in the electric motor of FIG. 7;

9 is an essential part enlarged explanatory view showing a flow of magnetic flux in the electric motor of FIG. 7;

10 is an essential part enlarged explanatory view showing a flow of a magnetic flux in the electric motor of FIG. 7;

[Explanation of symbols]

1 ... rotor, 2a, 2b, 2c ... rotor core, 3a, 3
b, 3c, 3d, 3e, 3f: magnet, 5: stator, 6
a, 6b ... stator core, 7, 7a, 7b, 7c, 7d ...
Tooth part, 8 ... slot, 9a, 9b ... slot opening, 1
2a, 12b, 12c, 13a, 13b, 13c: Core portions between magnets.

 ──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Seiichi Kaneko 68-4 Sakae, Kisosaki-cho, Kuwana-gun, Mie Prefecture

Claims (2)

[Claims] 1. A magnet, one of which is convex and the other of which is concave, are buried in multiple layers from the axis side of the rotor core to the opposite axis side with the convex side facing the rotation axis for each pole. In a motor having a rotor configured as described above, and a stator having windings mounted on a stator core having a plurality of slots opened toward the rotor, the magnets adjacent to each other in each pole of the rotor may be connected to each other. An electric motor characterized in that a width of an iron core portion interposed therebetween is larger than a width of an opening of the slot. 2. A plurality of magnets each having a convex surface and a concave surface formed by embedding a magnet having a concave surface on each of the poles, with the convex surface facing the rotation axis and extending from the axis side of the rotor core to the opposite axis side. In a motor having a rotor configured as described above and a stator having windings mounted on a stator core having a plurality of slots opened toward the rotor side, the motor adjacent to the rotor pole portion is interposed therebetween. An electric motor characterized in that a width of an iron core portion interposed between magnets is so narrow as to be sufficiently saturated by a magnetic flux of the magnets.