JPH0739091A - Rotor structure of synchronous machine and synchronous motor - Google Patents

Abstract

PURPOSE:To increase the reluctance torque Tr of a synchronous motor having salient poles on the outer circumference of its rotor and increase the output torque of the motor. CONSTITUTION:Permanent magnets 52 are attached to the outer circumference of the rotor of a three-phase synchronous motor and salient pole 71 and or 74 is provided between the permanent magnets 52. A slit 81 and or 84 is formed in the center part of the salient pole 71 and or 74 in a radial direction and, further, the inner circumference side end of the slit 81 and or 84 is extended along the inner circumference. As a result, a loop-shaped magnetic path in the salient poles is difficult to be formed and a d-axis inductance Ld is reduced. On the other hand, a q-axis inductance Lq is increased. As a result, a reluctance torque Tr which is proportional to the difference between the a-axis inductance Ld and the 1-axis inductance Lq can be increased. Therefore, if the output torque of the synchronous motor is increased, the performance (for instance, the running distance, the maximum speed, etc.) of an electric vehicle on which the motor is mounted can be improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rotor structure of a synchronous machine such as a synchronous motor or a synchronous generator having a permanent magnet as a field magnet in its rotor, and a synchronous motor adopting this rotor structure.

[0002]

2. Description of the Related Art Conventionally, when a synchronous motor is taken as an example of this type of synchronous machine, the rotor of the synchronous motor is provided on the surface or inside of the rotor as shown in Japanese Patent Publication No. 62-60906. A permanent magnet is provided, and a rotating magnetic field is generated by a coil wound around a slot on the stator side, and the rotor is rotated by this interaction.

Further, salient poles are provided between permanent magnets provided on the outer circumference of the rotor to facilitate the passage of magnetic flux in the horizontal axis (d-axis) direction due to the armature current through the rotor core, and the vertical axis (q-axis). It has been proposed to make effective use of the reluctance torque (reaction torque) by increasing the inductance Lq of (1) above the inductance Ld of the d-axis (for example, in Japanese Utility Model Publication 62-).
88463).

[0004]

However, in the conventional synchronous motor having salient poles, only a slight examination has been made regarding the shape and arrangement of salient poles, and the rotor that maximizes reluctance torque is used. Regarding the structure,
It was hard to say that sufficient consideration was made. Therefore,
There is still room for increasing the output torque of the motor by effectively utilizing the reluctance torque and for downsizing the motor shape at the same torque.

Incidentally, this point also applies to a synchronous generator having a similar structure. The present invention takes not only the relationship between the permanent magnets and the salient poles but also the structure of the rotor itself, and aims to maximize the reluctance torque.

[0006]

A rotor structure of a first synchronous machine according to the present invention, in which a rotor is provided with permanent magnets, has a high magnetic permeability between a plurality of permanent magnets provided on the outer periphery of the rotor. 1
A salient pole made of the above material is provided, and a region having a magnetic permeability lower than that of the first material is provided at a position where the salient pole is divided along the radial direction of the rotor.

This region may be provided as an air gap or may be made of another material having a low magnetic permeability, such as copper, aluminum, stainless steel, or synthetic resin. When other materials are used, it is also useful to serve as a fixing member for fixing the laminated thin plates of the rotor.

The reason why the region having a low magnetic permeability is provided at the position where the salient pole is divided in the radial direction is to prevent the d-axis inductance Ld from increasing due to the loop-shaped magnetic path formed inside the salient pole. Therefore, this region may be provided at a position deviated from the center of the salient pole, and if the material having a low magnetic permeability is filled or inserted, the salient pole is not
It does not matter if it is divided into the above. Further, this area is not limited to the inside of the salient pole, and is further inside the rotor,
In some cases, it is also desirable that the rotor extends to the innermost position. This region may have a slit shape, or may have a trapezoidal shape whose width becomes wider toward the inner peripheral side. Further, at the position on the inner circumference side of the rotor, it is also preferable to have a shape that spreads in the circumferential direction of the rotor in order to increase the difference between the axial inductances.

In the rotor structure of the second synchronous machine of the present invention, the rotor is provided with a permanent magnet, the salient pole made of the first material having a high magnetic permeability is provided on the outer periphery of the rotor, and the salient pole is A region having a lower magnetic permeability than the first material is provided at a position divided along the radial direction of the rotor, and the region having a lower magnetic permeability is provided.
Further, a permanent magnet that generates a magnetic flux in the circumferential direction of the rotor is arranged on the inner circumferential side of the rotor. Like the first rotor structure, the shape and arrangement of the regions may have various modes.

Further, the synchronous motor of the present invention includes the rotor having the above-mentioned first and second rotor structures.

[0011]

[Operation] As a synchronous machine using a permanent magnet, a synchronous motor,
That is, taking a synchronous motor as an example, the output torque T of the synchronous motor is obtained by the following equation (1). T = Tm + Tr (1) Here, Tm is the torque due to the magnetic field φm of the permanent magnet, and Tr is the reluctance torque. Tr is calculated by the following equation (2). Tr = P (Lq-Ld) · Iq · Id (2) where P is the number of pole pairs of the permanent magnet, Lq is the q-axis inductance, Ld is the d-axis inductance, and Iq and Id are the axes of the armature current. It is an ingredient. From this equation, it is generally understood that the reluctance torque Tr can be increased if the q-axis inductance Lq is large and the d-axis inductance Ld is small. The torque Tm due to the permanent magnet is determined as Tm = φm · Iq (3)

On the other hand, according to the first synchronous machine rotor structure of the present invention, the small inside of the salient pole is provided by the region of low magnetic permeability provided at the position where the salient pole is divided along the radial direction of the rotor. It becomes difficult to form a magnetic path. As a result, the magnetic path inductance due to the permanent magnet (d-axis inductance) is reduced, and the difference between the q-axis inductance and the d-axis inductance is increased. Therefore, in the synchronous motor adopting this rotor structure, the reluctance torque increases and the output torque of the entire motor also increases. In the case of the synchronous generator, the power generation efficiency is improved with the same torque.

If the region of low magnetic permeability is extended to the innermost circumference of the member in which the magnetic path is formed, the S of the adjacent permanent magnets will be increased.
The region of low magnetic permeability is also present in the magnetic path of the magnetic flux created by the pole and the N pole. Further, if the end portion on the inner peripheral side of the region having a low magnetic permeability is extended in the circumferential direction of the rotor, it becomes more difficult to form a small magnetic path inside the salient pole. Even with such a method, the reluctance torque can be increased.

According to the rotor structure of the second synchronous machine of the present invention, the magnetic flux in the d-axis direction flows from the permanent magnet provided on the innermost peripheral side of the rotor to between the salient poles, that is, between the salient poles. A magnetic path is formed to reach the stator side through the gap with the stator side. An air gap is interposed in this magnetic path, and it is difficult to form a small magnetic path inside the salient pole. As a result, the inductance of the magnetic path (d-axis inductance) due to the permanent magnet is reduced, and the same operation as the first rotor structure is brought about.

[0015]

Preferred embodiments of the present invention will be described below in order to further clarify the structure and operation of the present invention described above. FIG. 1 shows a rotor 50 as an embodiment of the present invention.
FIG. 2 is a plan view showing the shape of FIG. 2, and FIG. 2 is a sectional view showing the structure of a three-phase synchronous motor 40 incorporating this rotor 50.

First, referring to FIG. 2, a three-phase synchronous motor 40
The overall structure of will be described. This three-phase synchronous motor 40
Is composed of a stator 30, a rotor 50, and a case 60 that houses them. The rotor 50 has a permanent magnet 52 affixed to the outer periphery thereof, and a rotary shaft 55 provided at the center of the shaft.
Are rotatably supported by bearings 61 and 62 provided on the case 60.

The rotor 50 is formed by laminating a plurality of rotors 57 formed by punching non-oriented electrical steel sheets.
As shown, the rotor 57 has four
The salient poles 71 to 74 are provided. Slits 81 to 84 are provided at the centers of the salient poles 71 to 74, and the inner peripheral side end portions of the slits 81 to 84 are extended in the circumferential direction of the rotor 57, and circumferential slits 91 to 84 are provided. 94 are formed. Each of the rotors 57 has exactly the same size and shape, and has the slits 81.
To the rotary shaft 5 using a jig for positioning by
The slits 81 to 84 are laminated so as to be aligned in the axial direction of 5. After lamination, the rotary shaft 55 is press-fitted to form the laminated rotor 5
Temporarily fix 7. A rotor 57 made of this electromagnetic steel sheet
An insulating layer and an adhesive layer are formed on its surface, and the adhesive layer is melted and fixed by heating to a predetermined temperature after lamination.

After the rotor 50 is formed in this way, a permanent magnet 52 is attached to the outer peripheral surface of the rotor 50 at an intermediate position between the salient poles 71 to 74 in the axial direction. This permanent magnet is magnetized in the thickness direction. When the rotor 50 is assembled to the stator 30, the permanent magnet 52 forms a magnetic path Md that penetrates the adjacent permanent magnet 52, the rotor 57, and the stator 20.

The stator 20, which constitutes the stator 30, is formed by punching out a thin sheet of non-oriented electrical steel sheet like the rotor 57, and has a total of 12 teeth 22 as shown in FIG. A coil 32 for generating a rotating magnetic field in the stator 30 is wound around the slot 24 formed between the teeth 22 (see FIG. 2). Incidentally, the stator 2
On the outer periphery of 0, a bolt hole 36 through which a fixing bolt 34 is inserted
Are provided at four locations.

The stator 30 is temporarily fixed by heating and melting the adhesive layer while the plate-shaped stators 20 are stacked and pressed against each other. In this state, the coil 32 is wound around the tooth 22 to complete the stator 30, and then the stator 30 is assembled to the case 60 and fixed to the bolt hole 36 by the bolt 3 for fixing.
4 through and tighten it to fix the whole. Further, the rotor 50 is rotatably assembled with the bearings 61 and 62 of the case 60, whereby the synchronous three-phase motor is completed.

When an exciting current is supplied to the stator coil 32 of the stator 30 so as to generate a rotating magnetic field, a magnetic path Mq penetrating the adjacent salient pole, rotor 57 and stator 20 is thereby formed. The axis through which the magnetic flux formed by the permanent magnet 52 penetrates the rotor 50 in the radial direction is called the d-axis, and the magnetic flux formed by the stator coil 32 of the stator 30 penetrates the rotor 50 in the radial direction. The axis is called the q axis. In this embodiment, both axes form a 45 degree angle.

As shown in FIG. 1, the rotor 50 of this embodiment.
Is provided with slits 81 to 84 along the radial direction at the centers of salient poles 71 to 74 provided between the adjacent permanent magnets 52, and the inner peripheral side of the slits 81 to 84 is
There are circumferential slits 91 to 94 that spread in the circumferential direction. The slit is an air gap for magnetic flux, and its magnetic permeability is low. Since the magnetic flux tries to form a magnetic path while avoiding the slits 81 to 84 which are air gaps, the magnetic path Md formed by the permanent magnet 52 is the rotor 50.
Passing through the inner circumferential side of the circumferential slits 91 to 94 of
From the teeth 22 facing the permanent magnets 52 to the stator 2
It goes through the part of the yoke of 0. Since the salient poles 71 to 74 existing between the two permanent magnets 52 are radially divided by the slits 81 to 84 as air gaps, a small loop-shaped magnetic path is formed inside the salient poles 71 to 74. It is not formed. Therefore, the d-axis inductance Ld becomes extremely small.

On the other hand, the magnetic path Mq formed so as to pass through the salient poles 71 to 74 when the stator coil 32 is energized is
The salient pole 7 passes through the outer peripheral side of the circumferential slits 91 to 94.
It goes through the portion of the yoke from the slot 24 facing 1 to 74. The q-axis inductance Lq related to this magnetic path has a sufficiently large value as compared with the d-axis inductance Ld.

As a result, in light of the equation (2), (Lq-
Ld) becomes large, the reluctance torque Tr becomes large, and the output torque of the three-phase synchronous motor 40 is increased by about 5 to 8% as compared with the conventional one having a simple salient pole. As a result, if the same torque is obtained, the motor shape can be made small and lightweight. This means that the performance (driving distance, maximum speed, etc.) of a device equipped with the three-phase synchronous motor 40 of the embodiment, for example, an electric vehicle can be improved. Further, the efficiency of the motor is increased, which contributes to energy saving, and heat generation can be suppressed by the amount of the improved efficiency.

In this embodiment, since the inner peripheral side ends of the slits 81 to 84 are extended in the circumferential direction, it is difficult to form magnetic paths inside the salient poles 71 to 74.
A modification of this embodiment is shown in FIG. As shown in FIG. 3, if the salient poles 71 to 74 are simply completely divided in the radial direction by the slits 81a to 84a, it becomes difficult to form a loop magnetic path inside the salient poles 71 to 74. Ld becomes smaller and reluctance torque Tr
Can be large. However, in this case, an air gap exists in the magnetic path Md, and the magnetic field φm generated by the permanent magnet 52.
Becomes smaller. Therefore, the size of the air gap is adjusted so that the advantage of improving the relanking torque Tr can be fully utilized for improving the torque of the entire motor.

When the slit that divides the salient pole is formed halfway in the radial direction, the d-axis inductance Ld is reduced by the simple slit shape and the shape in which the inner peripheral end is extended in the peripheral direction as in the first embodiment. The effect on is different. This point is shown in FIG. 4 as a relationship between the slit shape and the shape of the magnetic path inside the salient pole. Since the magnetic permeability of the air gap is several orders of magnitude lower than that of the electromagnetic steel plate of the rotor 57, it is difficult to form a magnetic path in the path passing through the air gap. Compared with the simple radial slit 81b shown in FIG. It can be seen that the slit 81 extending in the circumferential direction shown in (B) is less likely to form a magnetic path inside the salient pole 71.

Next, a second embodiment of the present invention will be described. FIG. 5 is a plan view showing the structure of the rotor 150 of the second embodiment. As shown, this rotor 150
The rotating shaft 155 is formed in a prismatic shape having a square cross section except for the bearings 61 and 62, and the permanent magnet 1 is formed on each side surface thereof.
52 is attached. Further, special-shaped rotor assemblies 111 to 114 in which non-oriented electrical steel sheets are laminated are fixed to the side surfaces of the four permanent magnets 152. In this embodiment, since the permanent magnet 152 can be formed in a quadrangular prism shape, it is possible to secure a sufficient thickness, and the rotor assembly 11
It is also easy to fix 1 to 114.

The rotor 150 completed by fixing the rotor assemblies 111 to 114 is rotatably assembled to the case in which the stator and the bearing are incorporated, as in the first embodiment, and the three-phase synchronous motor is completed. . This rotor 150
As shown in the figure, the salient poles 171 to 174 are formed at positions separated by 90 degrees by the convex portions provided at the left and right ends in the circumferential direction of the rotor assemblies 111 to 114. A portion having a small outer diameter between the salient poles 171 to 174 acts as air gaps 161 to 164 with respect to the magnetic flux generated by the permanent magnet 152.

Since each rotor assembly 111 to 114 has a fan shape in which the angle formed by the edges on both sides in the circumferential direction is an obtuse angle, the salient poles 171 to 174 are formed in the center portion of the permanent magnet 152. Large trapezoidal space 1
81 to 184 will be provided. This space 18
1 to 184 are air gaps for the magnetic flux and act so as not to form a magnetic path inside the salient poles 171 to 174. Therefore, the gaps 161 to 164 between the outer circumference of the rotor assembly 111 to 114 and the stator are present. Together with this, the d-axis inductance Ld becomes smaller.
On the other hand, the q-axis inductance Lq increases, and as a result, the reluctance torque Tr increases.

In this embodiment described above, the reluctance torque Tr can be increased to increase the output torque of the motor, as in the first embodiment. Moreover, in the present embodiment, since the permanent magnet 152 can be arranged inside the rotor 150 and the direction of magnetization is orthogonal to the radial direction, its thickness is increased and the magnetic field of the permanent magnet that directly affects the output torque is reduced. It is easy to increase the strength φm. Also,
The space portions 181 to 184 can be made large, and d
The axial inductance Ld can be made sufficiently small.

In this embodiment, the rotor assemblies 111 to 114 are fixed to the permanent magnet 152. However, as shown in FIG. 6, a non-oriented electrical steel sheet is punched to form an integral rotor 201. After stacking and fixing, the permanent magnet 202
There is no problem with the structure in which the is inserted and fixed. In this case, the overall strength can be easily ensured and the rotary shaft 2
No. 05 can also use a normal shaft material. Further, the shape between the space portions 181 to 184 does not need to be limited to the shape in which the width gradually increases toward the inner peripheral side as in the embodiment, and is, for example, the slit shape shown in FIG. There is no problem with a structure in which a permanent magnet is arranged further inside.

The embodiment of the present invention has been described above.
The present invention is not limited to these embodiments, and for example, a structure as a synchronous machine having a structure with one pole, two or four slots or more, a structure applied to a synchronous generator, and the like are beyond the scope of the present invention. Needless to say, the present invention can be carried out in various modes within the range not covered.

As another embodiment of the present invention, a member made of a material having a low magnetic permeability (eg, copper or synthetic resin) is inserted, press-fitted or filled in the slit portion to fix the laminated rotor 57. It is possible to adopt a different structure, or after punching out a rotor without a slit, irradiating a laser or the like to form a region having a low magnetic permeability in the same shape as the slit. In the former case, there is an advantage that the rotor can be fixed easily. On the other hand, in the latter case, it is not necessary to punch out the slits, which simplifies the manufacturing process.
There is an advantage that the strength of the rotor is also improved. Since there are no slits, it is easy to handle the rotor before stacking, and also stack and fix. When the slit is not provided, it is easy to balance around the rotor axis.

[0034]

As described above, the first and second aspects of the present invention
The rotor structure of the synchronous motor of 1) has an excellent effect that the d-axis inductance can be reduced and a synchronous motor having a large difference between the q-axis inductance and the d-axis inductance can be easily manufactured. In the rotor structure of the second synchronous motor of the present invention, the degree of freedom of the shape of the permanent magnet is high, and it is easy to increase the strength of the magnetic field by increasing the thickness of the permanent magnet.

Further, in the synchronous motor adopting the rotor structure of the present invention, the reluctance torque is increased and the output torque can be increased. Therefore, if the torque is the same, the shape can be reduced, and the efficiency as a motor can be improved,
It can also contribute to energy saving. In addition, it becomes possible to improve various performances of equipment equipped with this motor.

[Brief description of drawings]

FIG. 1 is a plan view showing the structure of a three-phase synchronous motor that is an embodiment of the present invention.

FIG. 2 is a cross-sectional view showing the structure of a three-phase synchronous motor 40 incorporating the rotor 50 of the embodiment.

FIG. 3 is an explanatory diagram showing a modified example of the first embodiment.

FIG. 4 is an explanatory diagram illustrating a magnetic path inside a salient pole.

FIG. 5 is a plan view of a rotor 150 showing a second embodiment of the present invention.

FIG. 6 is a plan view of a rotor showing a modified example of the second embodiment.

[Explanation of symbols]

 20 ... Stator 22 ... Teeth 24 ... Slot 30 ... Stator 32 ... Stator coil 34 ... Bolt 36 ... Bolt hole 40 ... Three-phase synchronous motor 50 ... Rotor 52 ... Permanent magnet 55 ... Rotation shaft 57 ... Rotor 60 ... Case 61 , 62 ... Bearings 71 to 74 ... Salient poles 81 to 84 ... Slits 91 to 94 ... Circumferential slits 111 to 114 ... Rotor assembly 150 ... Rotor 152 ... Permanent magnet 155 ... Rotation shafts 161 to 164 ... Air gaps 171 to 174 ... Salient poles 181 to 184 ... Space portion 201 ... Rotor 202 ... Permanent magnet 205 ... Rotation axis Ld ... d-axis inductance Lq ... q-axis inductance

Claims (5)

[Claims] 1. A rotor structure of a synchronous machine having a rotor with permanent magnets, wherein salient poles made of a first material having high magnetic permeability are provided between a plurality of permanent magnets provided on the outer circumference of the rotor. A rotor structure for a synchronous machine, wherein a region having a magnetic permeability lower than that of the first material is provided at a position where the salient pole is divided in the radial direction of the rotor. 2. The rotor structure for a synchronous machine according to claim 1, wherein the region has a shape that widens in the circumferential direction of the rotor at a position on the inner circumferential side of the rotor. 3. The rotor structure for a synchronous machine according to claim 1, wherein the region has a shape extending to a position of an innermost circumference of a member forming a magnetic path of the rotor. 4. A rotor structure of a synchronous machine having a rotor with permanent magnets, wherein a salient pole made of a first material having a high magnetic permeability is provided on the outer periphery of the rotor, and the salient pole is provided in a radial direction of the rotor. A region having a magnetic permeability lower than that of the first material is provided at a position to be divided along, and the region having a lower magnetic permeability is further provided on the inner peripheral side of the rotor,
A rotor structure of a synchronous machine in which permanent magnets that generate magnetic flux are arranged in the circumferential direction of the rotor. 5. A synchronous motor comprising a rotor having a rotor structure according to claim 1.