JPH11146584A - Synchronous motor with permanent magnet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a synchronous motor having permanent magnets for improving the strength against demagnetization, while adopting a concentrated winding method. SOLUTION: In a synchronous motor having a stator with a concentrated winding method, the outer periphery of both the end portions of a permanent magnet 6 is inserted into the inner side in radial direction form the outer periphery of a rotor 2 by taking a means such as forming a cut and removed portion 11 on its outer periphery at the both the end portions in peripheral direction of a permanent magnet 6 arranged at the outer periphery of the rotor 2, by which the strength against demagnetization of the permanent magnet 6 can be improved by reducing the effect of the demagnetization upon the permanent magnet 6, even if the demagnetization occurs from the end of neighboring tees 4 of the stator 1 to the side of the rotor 2, in a state where the magnetic poles of the coil and rotor are opposite to each other.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a permanent magnet synchronous motor having a permanent magnet for a field in a rotor, and more particularly to a permanent magnet synchronous motor having a concentrated winding type stator.

[0002]

2. Description of the Related Art In general, in a high-power permanent magnet synchronous motor, the number of teeth of a stator is increased to form a distributed winding system so that a combined magnetomotive force waveform approaches a sine wave.
In addition, the permanent magnet of the rotor uses a rare earth magnet having a high magnetic flux density and a high demagnetization resistance, and is further configured to detect the rotation phase of the rotor with a sensor and perform current phase control according to the rotor position. I have.

However, in the distributed winding method, the winding efficiency is low due to the complicated winding process, and the rare earth magnet is expensive, and the sensor for detecting the rotational phase is also expensive. is there.

Therefore, as shown in FIG. 19 (a), a low cost permanent magnet synchronous motor is constituted by a split core 22 (see FIG. 19 (b)) obtained by dividing a stator 21 for each tooth. Insulating paper 28 is applied to the teeth 26 of the split core 22.
, And a coil wire is wound thereon to form a concentrated winding coil 23. The concentrated winding split cores 22 are combined in an annular shape, fixed by welding, caulking, laser welding, or the like, and the stator is concentrated and wound. In this embodiment, an inexpensive ferrite magnet is used for the permanent magnet 25 of the rotor 24, and the current phase control detects the zero-cross point of the induced voltage generated in the neutral coil that does not flow the drive current, and performs the 120 ° conduction rectangular wave control. I thought of something to do.

In such a permanent magnet synchronous motor, 3n teeth (n is a natural number) of stators 21 arranged at equal intervals are connected in three-phase Y-connection, and 2n poles are opposed to the stator 21. The permanent magnet field is arranged. As described above, in the concentrated winding type n-pole permanent magnet synchronous motor, it is preferable to provide a 2n-pole permanent magnet field for 3n teeth.

In the example of FIG. 19, the number of poles of the rotor 24 is 8 (2n, n = 4), and the number of teeth of the stator is 12 (3
n, n = 4), and u ₁ , v ₁ , w
_1, u _2, coil of ···· v _4, w ₄ is wound around. Then, as shown in FIG.
The phase and the W phase are connected in series or in parallel as shown in FIG.

[0007]

By the way, in a general permanent magnet synchronous motor, in order to reduce magnetic flux leakage between teeth, as shown in FIG.
La is set to La> approximately 2Lg, where La is an interval between the stators 26, and Lg is an air gap between the stator 21 and the rotor 24. The permanent magnet 25 of the rotor 24 has a uniform thickness at both ends in the circumferential direction. However, if the same configuration is adopted in a low-cost permanent magnet synchronous motor as described above, local demagnetization of the permanent magnet occurs for the following reasons, and the required motor output Has been found to be a problem.

In other words, because of the concentrated winding method, adjacent teeth have different polarities and the inductance is increased, so that a demagnetizing field is easily applied to the rotor. In particular, when sensorless driving is performed, a demagnetizing field is more likely to be applied to the permanent magnet of the rotor at the time of startup or step-out. That is, as shown in FIG. 22, a state occurs in which the magnetic pole generated by the stator coil 23 and the magnetic pole of the permanent magnet 25 of the rotor 24 face each other.
Enter the permanent magnet 25 side as a demagnetizing field 27 for
In particular, when the permanent magnet 25 is a ferrite magnet, the demagnetizing field 2
7 causes a breakdown state, resulting in demagnetization.

Conventionally, there are a large number of motors of the concentrated winding type. However, when the teeth are very narrow and the polarity of adjacent teeth is reversed, a demagnetizing field is easily applied to the permanent magnet, and a protective material such as ferrite is easily applied. When a permanent magnet having a small magnetic force is used, the demagnetization proof strength becomes weak. In particular, when performing sensorless driving, there is a high possibility that a reverse magnetic field is applied at the time of startup or step-out, and there is a problem that demagnetization is easily caused.

The present invention has been made in view of the above-described conventional problems, and has as its object to provide a permanent magnet synchronous motor in which the demagnetization resistance of a permanent magnet in a rotor is improved while employing a concentrated winding method.

[0011]

SUMMARY OF THE INVENTION A permanent magnet synchronous motor according to the present invention is a permanent magnet synchronous motor having a concentrated winding type stator. The permanent magnet is formed in a recessed shape that penetrates radially inward from the outer periphery, and since the outer peripheries of both ends of the permanent magnet penetrate radially inward from the outer periphery of the rotor, the coil and the magnetic poles of the rotor face each other. In this case, even if a demagnetizing field is generated from between the adjacent teeth ends of the stator toward the rotor, the demagnetizing field can be prevented from passing through the permanent magnet, making it difficult for the demagnetizing field to act. Demagnetization proof strength can be improved.

The opening angle of the recessed portion from the center of the rotor is Am, and the opening angle of the teeth of the stator is As,
By making Am larger than (1/10) As, the above-mentioned effect can be exhibited, and by making Am smaller than (1/4) As, the generated magnetic flux of the permanent magnets reduces the utilization factor and the motor output decreases. An increase in cogging torque can be suppressed.

Further, by making the inner surface of the permanent magnet in the rotor radial direction flat, and increasing the thickness of the permanent magnet in the circumferential central portion, the demagnetization resistance of the central portion of the permanent magnet can be further improved.

In the case where the rotor is a surface mounting type in which a permanent magnet is mounted on the outer periphery of a rotor core, the demagnetization proof strength is reduced by forming a recessed portion at a cut-off portion obtained by cutting off both ends in the circumferential direction of the permanent magnet. It is possible to realize a configuration that is large, does not reduce the motor output, and can suppress the cogging torque by simple processing.

In the case where the rotor is of an embedded type in which permanent magnets are embedded in the outer peripheral portion of the rotor core, cutouts and slits are formed in the outer peripheral portions of the rotor core corresponding to both ends in the circumferential direction of the permanent magnet, so that leakage magnetic flux is reduced. Short-circuiting through the portion corresponding to the recessed shape portion of the rotor core made of a ferromagnetic material is prevented by these notches and slits, so that reduction in motor efficiency can be reliably prevented.

Also, in the case where the rotor is of the embedded type in which an inverted arc-shaped permanent magnet whose center of curvature is located radially outward of the rotor is embedded in the outer peripheral portion of the rotor core, the end of the permanent magnet facing the outer periphery of the rotor is connected to the rotor. By providing a cutout or a slit at a position corresponding to this end of the rotor core at a position radially inward from the outer diameter, the same effect as described above is exerted.

At this time, when the distance between the end of the permanent magnet and the outer diameter of the rotor core is Q, and the air gap between the stator and the rotor is Lg, the above effect can be reliably obtained by making Q larger than Lg. , Q smaller than 3 Lg, it is possible to prevent the magnetic field generated by the permanent magnet from weakening and the motor output from lowering, and to prevent the cogging torque from increasing due to a sudden change in the magnetic field. In addition, one of the notch or slit
The opening angle from the center of the rotor to the width of the portion corresponding to the end of the two permanent magnets is Am, and the opening angle of the teeth of the stator is As.
By making Am larger than (1/10) As, the above-mentioned effect can be surely obtained, and by making Am smaller than (1/4) As, the motor output decreases or the cogging torque increases. Can be prevented.

Further, when applied to a sensorless drive motor, the sensorless drive generally tends to be demagnetized, so that a particularly great effect is exhibited. In addition, by applying the above-described permanent magnet synchronous motor to a drive motor of a compressor for an air conditioner or an electric refrigerator, the cost can be reduced and a particularly great effect can be obtained.

[0019]

DESCRIPTION OF THE PREFERRED EMBODIMENTS (First Embodiment) A first embodiment of the present invention will be described below with reference to FIGS.

In FIG. 1, 1 is a stator, 2 is a rotor, and the stator 1 is composed of divided cores 3 of a number corresponding to the number of slots, and a coil (not shown) is mounted on the teeth 4 of each divided core 3. Each is wound independently and a concentrated winding method is adopted. The rotor 2 has a structure in which permanent magnets 6 composed of a plurality of ferrite magnets are fixed to the outer periphery of a rotor core 5 formed by laminating silicon steel sheets, and a rotating shaft (not shown) fixed through the shaft core portion is used as a bearing. Supported rotatably. A thin plate cylinder 7 made of stainless steel is fitted around the outer periphery of the rotor 2 or a reinforcing tape is wound around the outer periphery of the rotor 2 to secure necessary strength against centrifugal force.

In the illustrated example, the number n of pole pairs is four,
Are provided with eight (2n) permanent magnets 6, and the stator 1
Is composed of 12 (3n) divided cores 3. The current control for the coils of the stator 1 is configured to detect a zero-cross point of an induced voltage generated in a neutral coil through which no drive current flows, and to perform 120 ° conduction rectangular wave control.

As shown in FIG. 1B, the distance between the teeth 4 and 4 of the stator 1 is La, and the size of the air gap 8 between the stator 1 and the rotor 2 is Lg.
3Lg <La ≦ 2.0Lg is set. As a preferred specific numerical example, Lg is set to 0.4 to 0.6 mm, whereas La is set to 0.4 to 0.3 mm.

In the above configuration, the distance La between the ends of the adjacent teeth 4, 4 is determined by the size L of the air gap 8.
g is 2.0 times or less, so that leakage flux can be suppressed from flowing to the adjacent teeth 4 side and to the rotor 2 side, so that the coils of the stator 1 and the magnetic poles of the rotor 2 face each other. Even in this case, the demagnetizing field hardly acts on the permanent magnet 6 of the rotor 2, and the demagnetization proof strength of the permanent magnet 6 of the rotor 2 can be improved.

FIG. 2 shows the relationship between La / Lg and the demagnetization rate. Conventionally, La / Lg is set to be larger than 2,
In this case, the demagnetization rate became 1.5% or more, and it was difficult to secure the output. On the other hand, by setting La / Lg to 2.0 or less, the demagnetization rate became smaller than 1.5%, and The required demagnetization rate can be ensured. Also,
Since La is larger than 0.3 Lg, the leakage magnetic flux between the teeth 4 and 4 does not become excessively large, and the teeth edges interfere with each other due to a molding error of the divided core 3 and the stator 1 There is no such thing that it cannot be assembled with high accuracy.

Further, since the permanent magnet 6 of the rotor 2 is made of a ferrite magnet, it can be constructed at a lower cost than a rare-earth magnet, and even if it has the property of being easily demagnetized, the demagnetization proof strength is reduced as described above. Can be improved. Further, when the stator 1 is composed of the divided cores 3, the stator 1 can be assembled by winding the windings independently and efficiently for each of the divided cores 3, so that the productivity of the stator 1 is remarkably improved, and the cost is significantly increased. It can be reduced.

(Second Embodiment) Next, a second embodiment of the permanent magnet synchronous motor of the present invention will be described with reference to FIGS. The description of the same components as those in the first embodiment will be omitted, and only different points will be described. The same applies to the following embodiments.

In FIG. 3, the teeth 4 of the stator 1
0.3Lg <La ≦ 2.0Lg, where L is the interval between the four, Lb is the end thickness of the teeth 4 of the stator 1 and Lg is the size of the air gap 8 between the stator 1 and the rotor 2.
Lg <Lb <5Lg is set.

As described above, in addition to the above-described first embodiment, the end thickness Lb of the teeth 4 of the stator 1 is made larger than twice the air gap Lg between the stator 1 and the rotor 2, so that demagnetization is achieved. The flow of the magnetic flux to the rotor side can be further suppressed, and the demagnetization proof strength can be improved. Further, since Lb is set to be smaller than 5 Lg, there is no possibility that the leakage magnetic flux short-circuited between the teeth 4 and 4 becomes too large and the motor output is reduced.

FIGS. 4A and 4B show Lb / Lg, demagnetization rate and torque ratio when La / Lg is 1. FIG. FIG.
As shown in FIG. 4A, the demagnetization ratio decreases as Lb / Lg increases. However, when Lb / Lg increases, the leakage flux increases and the torque decreases as shown in FIG. Therefore, Lb / Lg is 2
By increasing the value, the demagnetization rate is reduced, and Lb /
By making Lg smaller than 5, torque reduction can be prevented.

It should be noted that the effect can be exerted only by increasing the end portion thickness Lb of the teeth 4 of the stator 1 as described above.

(Third Embodiment) Next, a third embodiment of the permanent magnet synchronous motor of the present invention will be described with reference to FIG.

In FIG. 5, in addition to the configuration of the second embodiment shown in FIG. 3, the opposing ends of the adjacent teeth 4, 4 of the stator 1 are cut off at the side edges on the rotor 2 side. A part 9 is provided (the end of the teeth 4 and the rotor 2
The interval between them is indicated by Lc. ).

The cutout 9 may be provided only at one end of the teeth 4 of the stator 1, that is, only at the end on the lower side in the rotation direction of the rotor 2 among the opposing ends of the adjacent teeth 4 and 4.

By providing the cutout portion 9 as described above, the air gap at the end of the teeth 4 can be increased, and the flow of the demagnetizing magnetic flux to the rotor side can be suppressed.

Further, in this embodiment, at the end of the tooth 4 from which the side edge of the rotor 2 has been cut off, the side edge opposite to the rotor side is protruded to secure the thickness of the end of the tooth 4. ing. Thereby, it is possible to further suppress the leakage magnetic flux from flowing to the rotor side, and it is possible to further improve the demagnetization proof strength.

It should be noted that the effect can be obtained only by providing the cutout 9 at the end of the teeth 4 of the stator 1.

(Fourth Embodiment) Next, a fourth embodiment of the permanent magnet synchronous motor of the present invention will be described with reference to FIGS. In the first to third embodiments, the stator 1
By devising the shape of the teeth 4 of the rotor 2, the demagnetizing magnetic flux
Although the example in which the flow to the side is suppressed has been described, in the following embodiments, the demagnetization magnetic flux passing through the rotor 2 is prevented from passing through the permanent magnet 6 to improve the demagnetization proof strength.

In FIG. 6, cutouts 11 are formed at the outer peripheral portions at both ends in the circumferential direction of each permanent magnet 6. This resection 11
6B, the opening angle Am at the center of the rotor is different from the opening angle As of the teeth 4 of the stator 1 as shown in FIG.
Are set to (1/10) As <Am <(1/4) As.

By providing the cutouts 11 at both ends of the permanent magnet 6 as described above, as shown in FIG. 7, a demagnetizing field 12 projecting toward the rotor 2 between the ends of the adjacent teeth 4 is formed. Even if it occurs, the demagnetizing field 12 passes through the cutout 11, so that it does not act to demagnetize the permanent magnet 6, and the demagnetization resistance of the permanent magnet 6 can be improved. Here, if Am is smaller than (1/10) As, the above effect cannot be effectively obtained. If Am is larger than (1/4) As, the motor output decreases or the cogging torque increases. .

(Fifth Embodiment) Next, a fifth embodiment of the permanent magnet synchronous motor of the present invention will be described with reference to FIG. In the fourth embodiment, the inner surface in the rotor radial direction of the permanent magnet 6 is an arc surface centered on the axis of the rotor 2 and the thickness of the permanent magnet 6 is constant. The inner surface in the radial direction of the permanent magnet 6 is formed by a plane 13. According to the present embodiment, since the thickness of the permanent magnet 6 at the central portion in the circumferential direction is increased, the demagnetization resistance at the central portion is improved.

(Sixth Embodiment) Next, a sixth embodiment of the permanent magnet synchronous motor of the present invention will be described with reference to FIG. In the fourth and fifth embodiments, the rotor 2 is configured by attaching the permanent magnet 6 to the outer peripheral surface of the rotor core 5. However, in the following embodiments including this embodiment, the permanent magnet 6 is attached to the rotor core 5. 5 and embedded.

9 (a) to 9 (c), permanent magnets 6 having cutouts 11 formed at the outer peripheral portions at both ends in the circumferential direction are embedded in the outer peripheral portion of the rotor core 5, and are further arranged in FIG. 9 (d). As shown, a cutout 1 at the outer peripheral edge of the rotor core 5
A notch 14 is formed in a recess corresponding to the portion 1.
FIG. 9A shows an example in which the inner surface of the permanent magnet 6 in the rotor radial direction is an arc surface centered on the center of the rotor and the permanent magnet 6 has a constant overall thickness.

FIG. 9B shows the permanent magnet 6 in which the inner surface in the radial direction is formed of the flat surface 13 and the thickness of the permanent magnet 6 at the central portion in the circumferential direction is increased. FIG. 9C shows an example of the rotor 2 having four poles. The inner surface of the permanent magnet 6 in the rotor radial direction is an arc surface centered on the rotor center, but the outer surface of the permanent magnet 6 in the rotor radial direction. Is a protruding arc surface 1 centered on a position radially outwardly eccentric from the center of the rotor 1
5 is formed so that both sides thereof enter the inside in the radial direction, and both sides thereof function in the same manner as the cutout 11.

In the present embodiment, since the cutout portions 11 or portions that function similarly are formed at both ends of the permanent magnet 6, the same effects as those of the fourth and fifth embodiments can be obtained. Further, if the outer periphery of the rotor core 5 is left circular because of the embedded type, the ferromagnetic material of the rotor core 5 exists on the outer periphery of the cutout portion 11 or a portion that functions in the same manner. Although the magnetic circuit is short-circuited, the notch 14 is provided in the present embodiment, so that the short-circuit of the leakage magnetic flux can be prevented, and the decrease in the motor efficiency can be surely prevented.

(Seventh Embodiment) Next, a seventh embodiment of the permanent magnet synchronous motor of the present invention will be described with reference to FIGS. In the sixth embodiment, a notch 14 is formed in a portion corresponding to the cutout 11 in the outer peripheral portion of the rotor core 5.
Although an example in which is formed is shown, in the present embodiment, FIG.
In (c), the outer periphery of the rotor core 5 is a cylindrical surface,
As shown in detail in FIG. 10D, a slit 16 is formed in a portion corresponding to the cutout 11. This slit 1
The interior of 6 may be air, but may be filled with resin, non-magnetic metal, or the like to ensure the strength of the rotor 2.

FIG. 10 (a) shows the inner surface of the permanent magnet 6 in the rotor radial direction being an arc surface centered on the center of the rotor.
Shows that the overall thickness is constant. FIG. 10B shows the permanent magnet 6 whose inner surface in the radial direction is formed of the flat surface 13 and whose thickness at the central portion in the circumferential direction of the permanent magnet 6 is increased. FIG. 10 (c) shows an example of the rotor 2 having four poles, and the protruding arc surface 1 centered on a position where the outer surface of the permanent magnet 6 in the radial direction of the rotor is eccentric radially outward from the center of the rotor.
5 is formed so that both sides thereof enter the inside in the radial direction, and both sides thereof function in the same manner as the cutout 11.

FIG. 11 shows the permanent magnet 6 shown in FIG. 10C in which the radially inner side surface is constituted by a projecting arc surface 17 having the same center as the projecting arc surface 15 on the outer peripheral surface.

In this embodiment, the opening angle Am of the slit 16 is (1/10) As <Am <with respect to the opening angle As of the teeth 4 of the stator 1 as shown in FIG.
(1/4) As is set. Also, the slit 16
Is set to be substantially equal to the opening angle As of the stator and (1.0 to 1.4) As.

In this embodiment, the same operation and effect as in the sixth embodiment shown in FIG. 9 can be obtained only by replacing the notch 14 with the slit 16. If the opening angle Am of the slit 16 is smaller than (1/10) As, the above effect cannot be obtained effectively. If Am becomes larger than (1/4) As,
The motor output decreases or the cogging torque increases.

(Eighth Embodiment) Next, an eighth embodiment of the permanent magnet synchronous motor of the present invention will be described with reference to FIGS. In the present embodiment, as shown in FIG.
As the permanent magnet 6 embedded in the rotor 2, an inverted arc-shaped permanent magnet 18 whose center of curvature is located radially outside the rotor 2.
Is used. The end of the permanent magnet 18 facing the outer peripheral portion of the rotor 2 is positioned radially inward from the outer diameter of the rotor by a suitable distance, and a slit 16 is formed in a portion of the rotor core 5 facing this end.

Further, as shown in FIG.
The distance between the end of the rotor core 5 and the outer diameter of the rotor core 5 is set as Q, and the size of the air gap 8 between the stator 1 and the rotor 2 is set as Lg, so that Lg <Q <3Lg. If Q is smaller than Lg, the effect of preventing the demagnetizing flux from entering the permanent magnet 18 cannot be sufficiently obtained, and if Q is larger than 3 Lg,
The magnetic field generated by the permanent magnet 18 is weakened to reduce the motor output, and the magnetic field changes suddenly, so that the cogging torque increases. Further, assuming that the opening angle of the width of the portion corresponding to the end of one permanent magnet 18 of the slit 16 from the center of the rotor is Am and the opening angle of the teeth 4 of the stator 1 is As, (1/1)
0) As <Am <(1/4) As is set. Also in this case, when the opening angle Am is smaller than (1/10) As,
If the above effects cannot be obtained effectively and Am becomes larger than (1/4) As, the motor output will decrease or the cogging torque will increase.

13 and 14 show an example in which the slit 6 is formed on the outer peripheral portion of the rotor core 5, but FIG.
As shown in FIG. 5, a notch 19 may be formed instead of the slit 6, and the size of the notch 19 in that case is set in the same manner as described above.

FIG. 16 shows another embodiment of the permanent magnet embedded type rotor other than the above embodiment. FIG.
(A) and (b) are different from the formation width (opening angle) of the slit 16 and the shape of the slit 16 of the eighth embodiment. FIG.
(C) shows a configuration in which the permanent magnet 6 is constituted by a plate-like magnet 6a. FIG. 16D shows a configuration in which the permanent magnets 6 are composed of multiple inverted arc-shaped permanent magnets 18a and 18b arranged in parallel in the radial direction, and the slit 16 is an end of each of the inverted arc-shaped permanent magnets 18a and 18b. Is formed. FIG.
(E) shows a pair of plate-like magnets 6b in which the permanent magnets 6 are arranged in a C-shape from the inside to the outside in the radial direction. FIG. 16 (f) shows a case where an inverted arc-shaped permanent magnet 18 is used as the permanent magnet 6, and a rotor core body 5a having a star-shaped cross section for fixing the rotor core 5 around each of the permanent magnets 18; And a rotor core cap 5b which sandwiches the permanent magnet 18 between the rotor core 5a and the outer periphery of the thin cylinder 7 to secure strength against centrifugal force. A slit 16 is formed between the ends of the rotor core body 5 a and the rotor core cap 5 b and between the thin cylinder 7.

(Ninth Embodiment) Next, a ninth embodiment of the permanent magnet synchronous motor of the present invention will be described with reference to FIGS. In the present embodiment, as shown in FIG. 17A, as the permanent magnets 6 embedded in the respective poles of the rotor 2, two layers of inverted arc-shaped permanent magnets 6a whose centers of curvature are located radially outside the rotor 2 are used. , 6b. The inner and outer periphery of the outer peripheral side permanent magnet 6a and the inner and outer periphery of the inner peripheral side permanent magnet 6b are located on concentric circumferential lines. Also, both permanent magnets 6
Both end sides of a and 6b are located along the outer periphery of the rotor 2 and close to it.

As shown in FIG. 17B, the width L ₁ of the outer permanent magnet 6a is larger than the width L ₂ of the inner permanent magnet 6b. The permanent magnets 6a of the larger of demagnetization resistance width L ₁ is large, while disposed on the outer peripheral side of the rotor 2 greatly affected by nearby demagnetizing field in the teeth 4, is it small in demagnetization resistance in a small width L ₂ By disposing the permanent magnet 6b away from the teeth 4 and on the inner peripheral side of the rotor 2 which is less affected by the demagnetizing field, the permanent magnet 6a having two layers
The demagnetization proof stress of the permanent magnet 6 as a whole made of 6b is increased. Further, a permanent magnet 6b disposed on the inner peripheral side of the rotor 2
Can increase the arc length, which contributes to improving the magnet torque. FIG.
Indicates the demagnetization proof stress when the widths L ₁ and L ₂ are set to various ratios, where L ₁ / (L ₁ + L ₂ ) is 0.1.
When it was in the range of 55 to 0.75, it was found that good demagnetization proof stress was exhibited. FIG. 18 shows the demagnetization proof stress in a ratio with the demagnetization proof stress when L ₁ = L ₂ is set to 1.

In the ninth embodiment, the permanent magnet 6 is composed of two layers of inverted arc-shaped permanent magnets 6a and 6b. However, the present invention is not limited to this. The permanent magnets of each pole of the rotor 2 can be constituted by a plurality of layers of belt-like permanent magnets projecting to the position where both ends approach the outer periphery of the rotor. It is sufficient that the width of the permanent magnet decreases in order from the direction toward the permanent magnet embedded in the inner peripheral side.

In FIG. 17, reference numeral 1 denotes a stator, 3
Is a split core, and 5 is a rotor core, which are configured similarly to those described in the first embodiment.

In the above embodiment, the case of a sensorless drive permanent magnet synchronous motor has been described. However, a sensor-type motor can be used, and demagnetization can be suppressed in this case as well.

[0059]

According to the permanent magnet synchronous motor of the present invention,
As is apparent from the above description, in the permanent magnet synchronous motor configured to perform the current phase control without the sensor having the concentrated winding type stator, the outer circumferences at both circumferential ends of the permanent magnet disposed on the outer circumference of the rotor are used. Is formed in a recessed shape that extends radially inward from the outer periphery of the rotor, so that when the coil and the magnetic poles of the rotor face each other, the distance between the adjacent teeth ends of the stator decreases toward the rotor. Even when a magnetic field is generated, the demagnetizing field hardly acts on the permanent magnet, so that the demagnetization proof strength of the rotor magnet can be improved.

At this time, when the opening angle of the recessed portion from the center of the rotor is Am and the opening angle of the teeth of the stator is As, and Am is larger than (1/10) As, the above effect can be exhibited. Further, by making Am smaller than (1/4) As, it is possible to prevent the magnetic flux generated by the permanent magnet from lowering the utilization factor, thereby reducing the motor output and increasing the cogging torque.

Further, by making the inner surface of the permanent magnet in the radial direction of the rotor flat, and increasing the thickness of the permanent magnet in the central portion in the circumferential direction, the demagnetization resistance of the central portion of the permanent magnet can be further improved.

In the case where the rotor is of a surface mounting type in which a permanent magnet is mounted on the outer periphery of a rotor core, the demagnetization resistance is reduced by forming a recessed portion at a cut-off portion obtained by cutting off both ends in the circumferential direction of the permanent magnet. It is possible to realize a configuration that is large, does not reduce the motor output, and can suppress the cogging torque by simple processing.

When the rotor is of the embedded type in which permanent magnets are embedded in the outer peripheral portion of the rotor core, cutouts or slits are formed in the outer peripheral portions of the rotor core corresponding to both ends of the permanent magnet in the circumferential direction, so that leakage magnetic flux is reduced. Short-circuiting through a portion corresponding to the recessed shape portion of the rotor core made of a ferromagnetic material can be prevented by these notches or slits, and a decrease in motor efficiency can be reliably prevented.

Also, in the case where the rotor is of the embedded type in which an inverted arc-shaped permanent magnet whose center of curvature is located radially outward of the rotor is embedded in the outer peripheral portion of the rotor core, the end of the permanent magnet facing the outer periphery of the rotor is connected to the rotor. By providing a cutout or a slit at a position corresponding to this end of the rotor core at a position radially inward from the outer diameter, the same effect as described above is exerted.

At this time, the distance between the end of the permanent magnet and the outer diameter of the rotor core is Q, and the air gap between the stator and the rotor is Lg. , Q smaller than 3 Lg, it is possible to prevent the magnetic field generated by the permanent magnet from weakening and the motor output from lowering, and to prevent the cogging torque from increasing due to a sudden change in the magnetic field. In addition, one of the notch or slit
The opening angle from the center of the rotor to the width of the portion corresponding to the end of the two permanent magnets is Am, and the opening angle of the teeth of the stator is As.
By making Am larger than (1/10) As, the above-mentioned effect can be surely obtained, and by making Am smaller than (1/4) As, the motor output decreases or the cogging torque increases. Can be prevented.

When the rotor is of an embedded type in which a plurality of layers of band-shaped permanent magnets are embedded, the central portion of which protrudes toward the center of the rotor and both ends extend to a position close to the outer periphery of the rotor. By constructing each permanent magnet such that its width decreases sequentially from the set permanent magnet to the permanent magnet embedded on the inner peripheral side, the demagnetization proof strength of the permanent magnet can be improved. .

Further, when applied to a sensorless drive motor, the demagnetization resistance can be increased while having an inexpensive configuration, so that a particularly great effect is exhibited. In addition, by applying the above-described permanent magnet synchronous motor to a drive motor of a compressor for an air conditioner or an electric refrigerator, the cost can be reduced and a particularly great effect can be obtained.

[Brief description of the drawings]

FIG. 1 shows a first embodiment of a permanent magnet synchronous motor of the present invention, wherein (a) is a cross-sectional view and (b) is an enlarged cross-sectional view of a main part.

FIG. 2 shows a slit interval and a stator of the embodiment.
5 is a graph showing a relationship between a ratio of an air gap between rotors and a demagnetization ratio.

FIG. 3 is an enlarged sectional view of a main part of a second embodiment of the permanent magnet synchronous motor of the present invention.

FIG. 4 is a graph showing a relationship between a thickness of a tooth end, a ratio of an air gap between a stator and a rotor, and a demagnetization rate, and a relationship between the ratio and a torque ratio in the embodiment.

FIG. 5 is an enlarged sectional view of a main part of a third embodiment of the permanent magnet synchronous motor of the present invention.

6A and 6B show a permanent magnet synchronous motor according to a fourth embodiment of the present invention, wherein FIG. 6A is a sectional view, and FIG. 6B is an enlarged sectional view of a main part.

FIG. 7 is an operation explanatory view of the embodiment.

FIG. 8 is a sectional view of a fifth embodiment of the permanent magnet synchronous motor of the present invention.

FIG. 9 shows a sixth embodiment of the permanent magnet synchronous motor of the present invention, wherein (a) to (c) are cross-sectional views of respective modified examples,
(D) is an enlarged sectional view of a main part of (a).

FIG. 10 shows a seventh embodiment of the permanent magnet synchronous motor of the present invention, wherein (a) to (c) are cross-sectional views of respective modifications, and (d) is an enlarged cross-sectional view of a main part of (a). It is.

FIG. 11 is a partially enlarged cross-sectional view of a modified example of FIG. 10C in the same embodiment.

FIG. 12 is an operation explanatory view in the embodiment.

FIG. 13 is a sectional view of an eighth embodiment of the permanent magnet synchronous motor of the present invention.

FIG. 14 is an operation explanatory diagram in the embodiment.

FIG. 15 is an explanatory diagram of an operation of a modification of the embodiment.

FIG. 16 is a cross-sectional view of various embodiments other than the above embodiment of the present invention.

17A and 17B show a ninth embodiment of the permanent magnet synchronous motor of the present invention, wherein FIG. 17A is a sectional view and FIG. 17B is an enlarged sectional view of a main part.

FIG. 18 is a graph showing the relationship between the ratio of the width between two layers of permanent magnets and the demagnetization proof stress in the same embodiment.

FIG. 19 shows a configuration of a conventional permanent magnet synchronous motor,
(A) is a sectional view, and (b) is a perspective view of the split core.

FIG. 20 is a coil connection diagram in a conventional example.

FIG. 21 is an enlarged sectional view of a main part in a conventional example.

FIG. 22 is an explanatory diagram of a demagnetizing action in a conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Stator 2 Rotor 4 Teeth 5 Rotor core 6 Permanent magnet 6a Permanent magnet 6b Permanent magnet 8 Air gap 11 Cutting part 13 Plane 14 Notch 15 Protruding arc surface 16 Slit 18 Reverse arc permanent magnet 19 Notch

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Nosunari Asano 1006 Kadoma Kadoma, Osaka Pref. Matsushita Electric Industrial Co., Ltd. 72) Inventor Hideo Hirose 1006 Kadoma Kadoma, Kadoma-shi, Osaka, Japan Matsushita Electric Industrial Co., Ltd.

Claims (15)

[Claims] In a permanent magnet synchronous motor having a concentrated winding type stator, the outer peripheries of both ends in the circumferential direction of a permanent magnet disposed on the outer peripheral portion of the rotor are formed into a recessed shape which is radially inwardly inserted from the outer periphery of the rotor. A permanent magnet synchronous motor characterized by being formed. 2. An opening angle of the recessed portion from the center of the rotor is Am, and an opening angle of teeth of the stator is As.
2. The permanent magnet synchronous motor according to claim 1, wherein (1/10) As <Am <(1/4) As. 3. The permanent magnet synchronous motor according to claim 1, wherein the inner surface of the permanent magnet in the rotor radial direction is a flat surface, and the thickness of the permanent magnet at the circumferential center is increased. 4. The rotor according to claim 1, wherein the rotor is a surface mount type having a permanent magnet mounted on an outer periphery of a rotor core, and a cut-out portion formed by cutting off both ends in the circumferential direction of the permanent magnet is formed. Item 2. A permanent magnet synchronous motor according to Item 1. 5. The rotor according to claim 1, wherein the rotor is an embedded type in which a permanent magnet is embedded in an outer peripheral portion of the rotor core, and a notch is formed in an outer peripheral portion corresponding to both circumferential ends of the permanent magnet in the rotor core. Permanent magnet synchronous motor. 6. The rotor according to claim 1, wherein the rotor is of an embedded type in which a permanent magnet is embedded in an outer peripheral portion of the rotor core, and slits are formed in outer peripheral portions corresponding to both circumferential ends of the permanent magnet in the rotor core. Permanent magnet synchronous motor. 7. In a permanent magnet synchronous motor having a concentrated winding type stator, the rotor is an embedded type in which an inverted arc-shaped permanent magnet whose center of curvature is located radially outside the rotor is embedded in the outer peripheral portion of the rotor core. A permanent magnet synchronous motor, wherein an end of the magnet facing the outer periphery of the rotor is located radially inward of the outer diameter of the rotor, and a cutout is formed in a portion corresponding to the end of the rotor core. 8. A permanent magnet synchronous motor having a concentrated winding type stator, wherein the rotor is an embedded type in which an inverted arc-shaped permanent magnet whose center of curvature is located radially outward of the rotor is embedded in the outer peripheral portion of the rotor core. A permanent magnet synchronous motor, wherein an end of the magnet facing the outer periphery of the rotor is located radially inward of the outer diameter of the rotor, and a slit is formed in a portion corresponding to the end of the rotor core. 9. The system according to claim 7, wherein a distance between the end of the permanent magnet and the outer diameter of the rotor core is Q, and an air gap between the stator and the rotor is Lg, and Lg <Q <3Lg. 8. The permanent magnet synchronous motor according to 8. 10. An opening angle from the center of the rotor of the width of a portion corresponding to one end of one of the notches or slits to the end of one permanent magnet is defined as Am, and an opening angle of teeth of the stator is defined as (1).
9. The permanent magnet synchronous motor according to claim 7, wherein As / 10 <As <Am <(1/4) As. 11. A permanent magnet synchronous motor having a concentrated winding type stator in which a rotor is embedded with a plurality of layers of strip-shaped permanent magnets embedded at a central portion protruding toward the center of the rotor and extending at both ends close to the outer periphery of the rotor. The permanent magnet is characterized in that each permanent magnet is configured such that its width decreases gradually from the permanent magnet embedded on the outer peripheral side of the rotor to the permanent magnet embedded on the inner peripheral side of the rotor. Magnet synchronous motor. 12. A two-layer strip-shaped permanent magnet is embedded in the rotor, and the width of the outer permanent magnet is L ₁ , and the width of the inner permanent magnet is L ₂ , and L ₁ / (L ₁ + L _2). ) Is 0.55
The permanent magnet synchronous motor according to claim 11, which is in the range of 0.75 to 0.75. 13. The permanent magnet synchronous motor according to claim 11, wherein the permanent magnet has an inverted arc shape. 14. The permanent magnet synchronous motor according to claim 1, wherein the permanent magnet synchronous motor is configured to be driven without a sensor. 15. A compressor for an air conditioner or an electric refrigerator configured to be driven by the permanent magnet synchronous motor according to any one of claims 1 to 14.