JPH11308795A - Permanent magnet type synchronous motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable reduction of cogging torque, without increasing the number of item parts and obtain a permanent magnet type synchronous motor capable of improving characteristics. SOLUTION: This synchronous motor is provided with a stator core 1 having a field winding of a plurality of phases, permanent magnets 5 which are arranged on the inside diameter of the stator core 1 separated by a specified air gap, formed into a cylindrical form, and magnetized in a plurality of poles in the circumferential direction, and a rotor core 6 which holds the permanent magnets 5 on the outside diameter, forms a magnetic path, and has trenches 7 having a specified width in the outside diameter part in contact with the inside diameter of the permanent magnets 5. The trenches 7 in the external diameter part of the rotor core 6 are arranged in the boundary part of each pole of the permanent magnets 5.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a permanent magnet type synchronous motor using a cylindrical permanent magnet for a rotor.

[0002]

2. Description of the Related Art FIG. 12 is a block diagram of a conventional permanent magnet type synchronous motor. In FIG.
The stator core 5 having a plurality of phases of windings (not shown) in the slot 3 and applying a rotating magnetic field to the rotor 4 is disposed on the inner diameter side of the stator core 1 and formed in a cylindrical shape. The permanent magnet 6 constitutes the magnetic path of the rotor 4 and the permanent magnet 5
The permanent magnet 5 is magnetized into a plurality of magnetic poles related to the number of poles of the stator core 1, and the magnet is magnetized into four poles so that adjacent magnetic poles have different polarities. It is shown that it is done.

[0003] In the permanent magnet type synchronous motor configured as described above, for example, three-phase windings of U-phase, V-phase, and W-phase are formed on the stator core 1 and fixed when a predetermined phase difference is applied. A rotating magnetic field is generated in the child core 1, a torque is generated between the magnet and the permanent magnet 5 of the rotor 4, and the rotor 4 is configured to rotate at a synchronous speed.

[0004]

As the permanent magnet 5 of the above-described permanent magnet type synchronous motor, an anisotropic ferrite magnet or the like is usually used, and each of the permanent magnets 5 having a fixed area is used. In the magnetic pole, the permeance coefficient (Bd / Hd) is different in each part of the magnetic pole. For example, the permeance coefficient is low at the center of the magnetic pole in the circumferential direction, and the leakage magnetic flux increases as approaching the boundary with the adjacent other pole. The permeance coefficient becomes high, and therefore, the magnetomotive force of the magnet is high at the center in the circumferential direction of the magnetic pole and low at the end adjacent to the other pole, and becomes non-uniform in the rotation direction. As a result, the stator core 1 Rotor 4 in relation to arc length at tip of teeth 2
Generates a cogging torque.

In order to suppress the cogging torque, it is conceivable to adjust the magnetizing force at each part in the circumferential direction of the magnetic pole.
Adjustment of the magnetizing force causes a decrease in performance and an increase in variation, making it difficult to obtain stable performance. For this reason, in a permanent magnet type synchronous motor in which it is necessary to suppress cogging torque, a magnetic pole piece (iron core) made of a magnetic material is disposed on the outer diameter of the magnet as disclosed in, for example, Japanese Patent Application Laid-Open No. Hei 7-212995. Although a structure that eliminates non-uniformity of the magnetizing force in the rotational direction by the isotropic magnetic permeability of the pole piece has been adopted, the arrangement of the pole piece having a predetermined thickness hinders miniaturization of the electric motor, and This unnecessarily increases the number of parts and the number of manufacturing steps.

SUMMARY OF THE INVENTION The present invention has been made to solve such a problem, and a permanent magnet type synchronous motor capable of reducing cogging torque without increasing the number of parts and improving characteristics. The purpose is to obtain an electric motor.

[0007]

SUMMARY OF THE INVENTION A permanent magnet synchronous motor according to the present invention is arranged with a stator core having a plurality of phase field windings and a predetermined gap in the inner diameter of the stator core.
A permanent magnet that is formed in a cylindrical shape and is magnetized to a plurality of poles in the circumferential direction, and a magnetic path is formed while holding the permanent magnet at its outer diameter, and has a predetermined shape at an outer diameter portion that is in contact with the inner diameter of the permanent magnet. A rotor core having a groove provided substantially in the axial direction, wherein the groove of the outer diameter portion of the rotor core is arranged at the boundary between the magnetic poles of the permanent magnet.

[0008] Further, a stator core having a plurality of phase field windings, and a stator core having a predetermined gap disposed inside the stator core inner diameter,
A permanent magnet that is formed in a cylindrical shape and is magnetized to a plurality of poles in the circumferential direction, and a magnetic path is formed while holding the permanent magnet at its outer diameter, and has a predetermined shape at an outer diameter portion that is in contact with the inner diameter of the permanent magnet. A rotor core having a groove provided substantially in the axial direction, wherein the groove of the outer diameter portion of the rotor core is disposed at a circumferentially central portion of each magnetic pole of the permanent magnet.

Further, a groove having an outer diameter of the rotor core is formed in a substantially V-shaped cross section. Furthermore, the groove having the outer diameter of the rotor core is constituted by a first groove having a predetermined shape and a second groove which is provided close to and on both sides of the first groove and smaller than the first groove. It was done. Further, the groove having the outer diameter of the rotor core is provided over the entire length of the rotor core in the axial direction. Further, the groove having the outer diameter of the rotor core is provided in a part of the rotor core in the axial direction. Furthermore, the groove of the rotor core outer diameter is set so that the groove width changes in the axial direction of the rotor core. Further, the groove having the outer diameter of the rotor core is skewed in the axial direction of the rotor core.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiment 1 1 and 2
FIG. 3 shows a configuration of a permanent magnet type synchronous motor according to Embodiment 1 of the present invention and a groove shape of a rotor core. In FIG. In the figure,
Reference numeral 1 denotes a stator core having teeth 2 and a slot 3, and a stator core for providing a rotating magnetic field to the rotor 4 having a plurality of windings (not shown) in the slot 3; A permanent magnet 6 formed in a cylindrical shape is a rotor core that forms a magnetic path of the rotor 4 and holds the permanent magnet 5 at its outer diameter. The inner diameter of the teeth 2 is used as a magnetic pole of the stator core 1. A plurality of grooves 7 each having a predetermined shape are provided in the outer diameter portion of the rotor core 6 which is opposed to the outer diameter of the permanent magnet 5 via a predetermined gap and which is in contact with the permanent magnet 5. And the grooves 7 are arranged corresponding to the boundaries between the magnetic poles of the permanent magnet 5. In FIG. 1, the permanent magnet 5 is magnetized into four poles, and the grooves 7 are provided at four locations on the boundary between the magnetic poles.

In the permanent magnet synchronous motor according to the first embodiment of the present invention, a groove 7 having a predetermined shape is provided on the outer diameter of the rotor core 6 at each magnetic pole boundary of the permanent magnet 5. Therefore, the magnetic resistance of the magnetic circuit including the permanent magnet 5 increases near the boundary between the magnetic poles, and the operating point of the magnet changes to decrease the permeance coefficient near the boundary. The amount and range in which the permeance coefficient is reduced can be adjusted according to the depth and width or the shape of the groove 7. By selecting and providing the shape of the groove 7, the distribution of the magnetic flux distribution in the rotation direction of the pole face of the magnet is provided. Changes can be mitigated. In this way, it is possible to reduce the cogging torque by making the magnetic flux distribution uniform without using unstable adjustment magnetization or using magnetic pole pieces made of a magnetic material, and a permanent magnet synchronous motor having stable characteristics. Can be obtained.

Embodiment 2 FIG. FIG. 3 shows a configuration of a permanent magnet type synchronous motor according to Embodiment 2 of the present invention. In this embodiment, as shown in the drawing, a groove 7 provided on the outer diameter of rotor core 6 is provided. The permanent magnet 5 is arranged at the center in the circumferential direction of each magnetic pole. With this configuration, the magnetic resistance at the center of the magnetic pole in the circumferential direction is increased as compared with the circumferential end of the magnetic pole, and the magnetic flux density at the center of the magnetic pole is compared with the magnetic flux density at the circumferential end. Because it drops
The so-called horizontal-axis magnetic flux can be made larger than the direct-axis magnetic flux to have a reverse saliency, and the torque characteristics by the reluctance torque can be improved.

Embodiment 3 FIG. 4 is a configuration diagram of a permanent magnet type synchronous motor according to a third embodiment of the present invention. As shown in the drawing, this embodiment gradually increases the outer diameter of the rotor core 6 at the center and deeper on both sides. A groove 8 having a substantially V-shaped cross section which becomes shallower is provided in the axial direction. By providing the groove 8 at the boundary between the magnetic poles, usually, when the cylindrical magnet is magnetized into a plurality of poles, the permeance coefficient in the circumferential direction of the magnet becomes higher as it is closer to the boundary between the magnetic poles. However, by forming the groove 8 having a V-shaped cross-sectional shape, the magnetic resistance increases as the magnetic pole portion approaches the magnetic pole end having a high permeance coefficient, and the effect of lowering the permeance coefficient increases.
The permeance coefficient in the circumferential direction can be made more uniform. By providing the V-shaped groove 8 at the circumferential center of each magnetic pole in the same manner as in the second embodiment, the magnetic resistance at the circumferential center of the magnetic pole can be changed at a predetermined inclination. It is possible to improve torque characteristics.

Embodiment 4 FIG. 5 shows a configuration of a permanent magnet type synchronous motor according to Embodiment 4 of the present invention. As shown in FIG. 5, this embodiment extends in the axial direction to the outer diameter of rotor core 6. First groove 9a of predetermined width and depth
And a second groove 9b, which is closer to both sides of the first groove 9a and has one or both of a width and a depth smaller than that of the first groove 9a. This groove 9a
In the case where the combination of the magnetic poles 9b and 9b is provided at the boundary between the magnetic poles, as in the third embodiment, the nearer to each magnetic pole end where the permeance coefficient is higher, the higher the magnetic resistance is, and the more uniform the permeance is over the entire pole face A coefficient can be obtained. Further, even if the grooves 9a and 9b are provided at the center in the circumferential direction of each magnetic pole, the rate of change of the permeance coefficient at the center of the magnetic pole changes, and the torque characteristics can be improved as in the second embodiment. It is.

Embodiment 5 6 to 11 show a groove shape of a permanent magnet synchronous motor according to a fifth embodiment of the present invention. FIG. 6 shows a case where the width of the groove 10 is different in the axial direction, and FIG. FIGS. 8 to 11 show the case where the grooves 1 are provided in a skewed state.
Reference numeral 2 denotes a state provided in a part of the rotor core 6 in the axial direction. When the grooves are irregular in this way, the permeance coefficient differs in each part of the permanent magnet 5 in the axial direction, but the difference in the permeance coefficient in the axial direction is averaged by the combination with the stator core 1. By selecting the shapes and lengths of these grooves, it is possible to adjust the permeance coefficient in the rotational direction, similarly to the V-shaped groove of the third embodiment and the plural grooves of the fourth embodiment.

[0016]

As described above, according to the permanent magnet type synchronous motor of the present invention, the outer diameter of the rotor core that holds the permanent magnet of the rotor and forms a magnetic path is substantially predetermined in the axial direction. A groove having a width or a predetermined shape is provided, and the groove is arranged at a boundary portion of each magnetic pole provided in the permanent magnet or at a central portion in a circumferential direction, and the circumferential shape of each magnetic pole is determined by the shape and configuration of the groove. Since the permeance coefficient of the direction can be adjusted,
The magnetic flux distribution in the circumferential direction of the magnetic pole surface can be adjusted without providing magnetic pole pieces on the outer surface of each magnetic pole or adjusting the amount of magnetization, reducing cogging torque and improving torque characteristics. Is possible, small and highly productive,
It is possible to obtain an excellent permanent magnet synchronous motor with little performance variation.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a permanent magnet type synchronous motor according to Embodiment 1 of the present invention.

FIG. 2 is an external view of a rotor core of the permanent magnet synchronous motor according to the first embodiment of the present invention.

FIG. 3 is a configuration diagram of a permanent magnet type synchronous motor according to Embodiment 2 of the present invention.

FIG. 4 is a configuration diagram of a permanent magnet type synchronous motor according to Embodiment 3 of the present invention.

FIG. 5 is a configuration diagram of a permanent magnet type synchronous motor according to Embodiment 4 of the present invention.

FIG. 6 is an explanatory diagram of a rotor core according to a fifth embodiment of the present invention.

FIG. 7 is an explanatory diagram of a rotor core according to a fifth embodiment of the present invention.

FIG. 8 is an explanatory diagram of a rotor core according to a fifth embodiment of the present invention.

FIG. 9 is an explanatory diagram of a rotor core according to a fifth embodiment of the present invention.

FIG. 10 is an explanatory diagram of a rotor core according to a fifth embodiment of the present invention.

FIG. 11 is an explanatory diagram of a rotor core according to a fifth embodiment of the present invention.

FIG. 12 is a configuration diagram of a conventional permanent magnet type synchronous motor.

[Explanation of symbols]

1 stator core, 4 rotors, 5 permanent magnets, 6 rotor cores, 7, 8, 9a, 9b, 10, 11, 12 grooves.

Claims (8)

[Claims] A stator core having a multi-phase field winding;
A permanent magnet which is arranged in the inner diameter of the stator core through a predetermined gap, is formed in a cylindrical shape, and is magnetized to a plurality of poles in a circumferential direction, holds the permanent magnet at its outer diameter and forms a magnetic path. And, provided with a rotor core having a groove provided substantially in the axial direction in a predetermined shape in the outer diameter portion in contact with the inner diameter of the permanent magnet,
A permanent magnet type synchronous motor characterized in that grooves of the outer diameter portion of the rotor core are disposed at boundaries between magnetic poles of the permanent magnet. 2. A stator core having a multi-phase field winding,
A permanent magnet which is arranged in the inner diameter of the stator core through a predetermined gap, is formed in a cylindrical shape, and is magnetized to a plurality of poles in a circumferential direction, holds the permanent magnet at its outer diameter and forms a magnetic path. And, provided with a rotor core having a groove provided substantially in the axial direction in a predetermined shape in the outer diameter portion in contact with the inner diameter of the permanent magnet,
A permanent magnet synchronous motor, wherein a groove of the outer diameter portion of the rotor core is disposed at a circumferentially central portion of each magnetic pole of the permanent magnet. 3. The rotor core outer diameter groove is provided in a substantially V-shaped cross-sectional shape.
A permanent magnet synchronous motor as described. 4. A groove having an outer diameter of a rotor core includes a first groove having a predetermined shape, and a second groove which is provided close to and on both sides of the first groove and smaller than the first groove. 3. The permanent magnet type synchronous motor according to claim 1, wherein: 5. The permanent magnet type as claimed in claim 1, wherein the groove of the rotor core outer diameter is provided over the entire length of the rotor core in the axial direction. Synchronous motor. 6. The permanent magnet type synchronous motor according to claim 1, wherein the groove of the rotor core outer diameter is provided in a part of the rotor core in the axial direction. Electric motor. 7. The rotor core outer diameter groove is provided so that the groove width changes in the axial direction of the rotor iron core. Permanent magnet synchronous motor. 8. The permanent magnet type synchronous motor according to claim 1, wherein the groove having an outer diameter of the rotor core is skewed in an axial direction of the rotor core. Electric motor.