JPH1189144A - Permanent magnet rotary electric motor and electric vehicle using it - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a small and light permanent magnet rotary electric motor with high torque. SOLUTION: This permanent magnet rotary electric motor 1 is composed of a stator 2, having a stator core 4 constituted of a magnetic body and stator winding wires 5 wound to the stator core 4 and of a rotor 3 having a rotor core 8 constituted of the magnetic body and permanent magnets 6 arranged in the rotor core 8 at almost equal intervals. Since the rotor cores 8 having magnetic permeability lower than that of the stator core 4 is set to be the state of magnetic saturation magnetic flux density lower than that of the stator core 4 in a bridge 83, magnetic flux leaking in the direction of a salient pole 82 from a magnetic pole piece 84 via the bridge 83, and higher torque can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a permanent magnet rotating electric machine and an electric vehicle using the same.

[0002]

2. Description of the Related Art In a drive motor used for an electric vehicle, particularly an electric vehicle, the amount of a battery loaded on the electric vehicle is limited, and it is necessary to secure a sufficient one-charge traveling distance with the limited amount. For this reason, it is desired to be small, lightweight and highly efficient. In order to reduce the size and weight of the electric motor, it is required to be suitable for high-speed rotation. As the high-efficiency drive motor, a permanent magnet rotating electric machine can be recommended rather than a DC rotating electric machine or an induction rotating electric machine. Further, even in the case of a permanent magnet rotating electric machine, a so-called internal arrangement in which a permanent magnet is arranged inside an iron core having a higher magnetic permeability than a permanent magnet as compared with a surface magnet motor in which a permanent magnet is arranged on the outer periphery of an iron core of a rotor. A magnet motor is suitable. This is because the internal magnet motor is made highly efficient by the field-weakening control, and has the advantage of being able to operate at high speeds.

As an application example of the above-described surface magnet motor to an electric vehicle, there is a technique disclosed in Japanese Patent Application Laid-Open No. 7-39091 (disclosed example 1). This technique discloses a configuration in which a permanent magnet is arranged at the center of a magnetic pole of a core of a rotor made of a material having high magnetic permeability. On the other hand, although it is an example applied to a motor of a compressor, an insertion hole for a permanent magnet is provided inside a rotor core made of a material having high magnetic permeability, for example, a silicon steel plate, and a permanent magnet is arranged in the hole. Regarding the structure of the internal magnet motor, see JP-A-5-2196.
There is a technique disclosed in Japanese Patent Application Publication No. 69 (Disclosure Example 2).

[0004]

However, the above prior art has the following problems. That is, the technology of the first disclosed example does not require an outer peripheral member for holding a permanent magnet, but on the other hand, does not allow a magnetic flux to leak between the poles via a magnetic pole piece on the outer peripheral surface of the permanent magnet, thereby failing to obtain a high torque. There are issues. on the other hand,
The technique of Disclosure 2 has problems to be improved in terms of high-speed rotation and effective use of permanent magnets due to the low mechanical strength of a magnetic material such as a silicon steel plate. Accordingly, an object of the present invention is to provide a small, lightweight, high-torque permanent magnet rotating electric machine having a configuration suitable for high-speed rotation and efficiently using permanent magnets, and an electric vehicle using the same.

[0005]

A feature of a permanent magnet rotating electric machine according to the present invention that achieves the above object is that a stator having a stator core and a stator winding wound on the stator core is provided.
In a permanent magnet rotating electric machine including a rotor having a rotor core and a permanent magnet disposed in the rotor core, the magnetic permeability of the rotor core in an operating state of the permanent magnet rotating electric machine is the fixed value. The point is lower than the permeability of the iron core. Further, an electric vehicle according to the present invention that achieves the above object uses the permanent magnet rotating electric machine according to claim 1 for driving the electric vehicle.

According to the present invention, the rotor core having a lower magnetic permeability than the stator core in the operating state of the permanent magnet rotating electric machine is provided with a magnetic saturation magnetic flux of the stator core at a bridge portion of the rotor core. Since the state of the magnetic saturation magnetic flux density is lower than the density, the magnetic flux leaking from the pole piece to the salient pole via the bridge is reduced, and higher torque can be obtained.

[0007]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a radial longitudinal sectional view showing a permanent magnet rotating electric machine according to one embodiment of the present invention. In the figure, a permanent magnet rotating electric machine 1 (hereinafter, referred to as a rotating electric machine 1) includes a stator 2 and a rotor 3. The stator 2 includes a stator core 4 and a stator winding 5 wound around the stator core 4. The structure of the stator 2 of the present embodiment is a distributed winding stator structure that is generally widely used. That is, the stator core 4 is
41, a stator yoke 42 for collecting magnetic flux passing through the teeth 41 to form a magnetic circuit, and a slot 43 formed between the teeth 41. 5 is wound and housed in the slot 43 from a slit portion (not shown) of the portion near the gap surface of the stator core 4.

On the other hand, the rotor 3 includes a rotor core 8 having a permanent magnet 6 therein, and a shaft 9 inserted into the rotor core 8. The N and S poles of the permanent magnet 6 are alternately inserted into permanent magnet insertion holes 7 provided on the outer peripheral portion (near the outer peripheral surface) of the rotor core 8. As shown in an enlarged view of the vicinity of the bridge of the rotor 3, the rotor core 8 includes a yoke 81,
Salient pole 82), a bridge 83, a pole piece 84, and an outer peripheral surface 85. That is, the rotor core 8 has a permanent magnet insertion hole 7 and a shaft hole (not shown) into which the shaft 9 is inserted, and when viewed from the permanent magnet 6 inserted into the permanent magnet insertion hole 7, the rotor core 8 rotates. A yoke 81 forming the center of the core 8, a salient pole 82 between the two poles of the permanent magnet 6 to form a magnetic pole part, and a magnetic pole piece 84 between the permanent magnet 6 and the outer peripheral surface 85 to form an outer magnetic pole part , And a bridge 83 which forms a connecting portion between the salient pole 82 and the pole piece 84. That is, it can be said that the salient pole 82 and the pole piece 84 are integrally connected by the bridge 83 on the outer peripheral portion of the rotor core 8.

FIG. 2 is an axial cross-sectional view showing a permanent magnet rotating electric machine according to one embodiment of the present invention. 1 denote the same components. In the figure, a rotating electric machine 1 includes a stator 2, a rotor 3, a housing 10, an end bracket 11, a bearing 12, a magnetic pole position detector PS for detecting positions of a permanent magnet 6 of the rotor 3, and a position of the rotor 3. And an encoder E for detection. Note that the encoder E is a position sensor for speed control. The above stator 2
Is a stator core 4 wound with a multi-phase stator winding 5 and held.
, And is fixed to the inner peripheral surface of the housing 10. The rotor 3 is rotatably held by a bearing 12 inserted into an end bracket 11 via a shaft 9 fitted to a rotor core 8. The rotating electric machine 1 is configured to be operated and controlled via a control device (not shown) by a detection signal of the magnetic pole position detector PS and an output signal of the encoder E.

The features of the rotating electric machine 1 according to the present embodiment are as follows. FIG. 3 is a diagram showing a state of magnetic saturation magnetic flux density of the stator core and the rotor core of one embodiment of the permanent magnet rotating electric machine according to the present invention. As shown in FIG. 3, the magnetic saturation magnetic flux density (G) of the rotor core is lower than the magnetic saturation magnetic flux density (G) of the stator core in any range of the magnetizing force (AT / CM). Has become. That is, the stator core 4 of the rotating electric machine 1 of the present embodiment uses a silicon steel plate (having a magnetic permeability of about 2.1 stellar) as a magnetic material. The rotor core 8 shows a higher magnetic permeability than the permanent magnet 6,
A steel plate (permeability is about 1.8 stellar) is used as a magnetic material that shows lower magnetic permeability than silicon steel plate. That is, by using a combination of magnetic materials in which the magnetic permeability of the rotor core 8 is lower than the magnetic permeability of the stator core 4 in the operation state of the permanent magnet rotating electric machine, the magnetic saturation magnetic flux density in each iron core is reduced. Each characteristic in the rotating electric machine operating state as shown in FIG. The stellar value indicating the magnetic permeability is a value measured at room temperature.

In other words, the feature of the permanent magnet rotating electric machine according to the present invention is that the magnetic saturation magnetic flux density on the rotor side is made lower than the magnetic saturation magnetic flux density on the stator side in the operating state of the permanent magnet rotating electric machine. It can be said that the magnetic material combination of the stator and the rotor is possible. Therefore, in addition to the combination of the first embodiment, for example, a combination of a magnetic material in which the stator is a permalloy material (permeability is about 2.3 stellar) and the rotor is a silicon steel plate, or the stator is a steel plate A combination of magnetic materials made of stainless steel (permeability is about 1.0 stellar) is possible. on the other hand,
The permanent magnet 6 shown by a rectangular parallelepiped uses a neodymium magnet. The rectangular parallelepiped permanent magnet has an advantage that the dimensional accuracy can be ensured as compared with the arc-shaped permanent magnet, the bridge 83 and the like can be accurately formed, and therefore, can be used for high-speed rotation without a rotor balancing operation. Since the magnetic permeability of neodymium magnets is about 0.7 stellar, even if the rotor core is made of stainless steel, it meets the basic specifications of a permanent magnet rotating electric machine that the rotor core shows higher permeability than the permanent magnet. I do.

The operation of the permanent magnet rotating electric machine is as follows. A sine wave current is supplied from a control device (such as an inverter) to the stator windings 5 of each phase shown in FIGS. In this case, the combined current of each phase is always a current that is in a positional relationship perpendicular to the permanent magnet flux, or a current that is in a positional relationship that is shifted by a predetermined phase (the combined magnetomotive force of each phase current is 90 degrees or more than that of the permanent magnet). (Weak-field-controlled current). In other words, by controlling the combined vector of the armature magnetomotive force generated by the current flowing through the stator winding 5 by the control device so as to face the rotation direction side from the center position of the salient pole 82, the rotating electric machine 1 In addition to the torque generated by the permanent magnet 6, the operation is performed so that reluctance torque generated by the salient poles 82 can be generated. At this time, as shown in FIG. 3, the bridge 83 of the rotor core 8 is in a characteristic state when a rotating electric machine having a magnetic saturation magnetic flux density lower than the magnetic saturation magnetic flux density of the stator iron core 4 is used. The magnetic flux leaking from the piece 84 to the salient pole 82 via the bridge 83 is reduced, which leads to the effective use of the magnetic flux of the permanent magnet 6 and higher torque.

On the other hand, the rotor made of a steel plate of the rotary electric machine 1 of the present embodiment has a higher mechanical strength than the rotor made of a silicon steel plate. It is also fully tolerable. Therefore,
The rotating electric machine 1 of the present embodiment is a permanent magnet rotating electric machine that can operate as an internal magnet electric motor (internal magnet type brushless motor) that rotates at high speed and generates high torque.

Here, the effective use of the permanent magnet 6 will be described. Generally, the torque T of the permanent magnet rotating electric machine is
It is expressed by the following equation. T = (E0 · Iq) / ω + (Xq−Xd) · Id · Iq / ω (Equation 1) where E0: induced voltage, ω: rotational angular velocity, Id, Iq: current on d and q axes, Xq, Xd: reactance of d and q axes, and the first term in equation (1) is
The second term is a salient pole due to the torque component due to the magnetic flux of the permanent magnet 6.
This is the reluctance torque component by 82. An increase in torque due to an increase in the reluctance torque component of the second term generally decreases the power factor and lowers the efficiency, and therefore cannot be adopted. Therefore, in order to increase the torque, it is important to make maximum use of the magnetic flux of the permanent magnet of the first term. However, since the amount of magnetic flux that can be emitted from the permanent magnet 6 is limited, it is important to reduce the leakage of the magnetic flux as much as possible so as to maximize the use of the permanent magnet. To this end, it can be said that it is desirable to reduce the amount of magnetic flux leaking from the magnetic pole piece 84 at the outer peripheral portion to the salient pole 82 via the bridge 83 in the amount of magnetic flux generated from the permanent magnet 6.

The idea of the present invention lies in the point that attention has been paid to the fact that it is possible to reduce the leakage magnetic flux in the above-described direction by lowering the magnetic characteristics (ie, magnetic permeability) of the rotor core 8. . That is, on the rotor side,
Since there is no place where the magnetic flux density rises extremely like the teeth 41 of the stator core 4 on the stator side, the magnetic saturation flux density is low on the rotor side which forms a magnetic circuit together with the stator side. It is noted that the use of materials does not affect the performance of the rotating electric machine as a whole. That is, a material having a low magnetic permeability, which does not cause a problem even if the magnetic saturation magnetic flux density is lower than that of the stator core 4 on the stator side, is used for the rotor core 8 on the rotor side, and the bridge of the rotor core 8 is bridged. 83
In the above, the state of the magnetic saturation magnetic flux density lower than the magnetic saturation magnetic flux density of the stator core 4 can be obtained.
The magnetic flux leaking from 84 to the salient pole 82 via the bridge 83 can be reduced.

In other words, the rotor core 8 is a magnetic material exhibiting characteristics lower than the magnetic saturation magnetic flux density of the stator core 4 in the operating state of the permanent magnet rotating electric machine. The magnetic flux leaking through the bridge 83 reaching the upper limit is suppressed, and the amount of magnetic flux emitted from the permanent magnet 6 is directed to the stator side (the stator core 4 side) as much as possible, so that the amount of magnetic flux generated from the permanent magnet 6 is effectively used. It is intended to be used.

As described above, the effective magnetic flux amount of the permanent magnet 6 can be increased, and the torque component of the permanent magnet 6 in the first term of the equation (1) is increased to increase the torque performance of the permanent magnet rotating electric machine. Is to improve. Regarding the increase in the amount of magnetic flux, the silicon steel sheet has a magnetic permeability of about 2.1.
The upper limit of the motor specification of the magnetic saturation magnetic flux density of the stator core 4 on the stator side using a silicon steel plate is
It will be about 2.1 stellar. On the other hand, since the steel plate has a magnetic permeability of about 1.8 stellas, the upper limit of the specification of the magnetic saturation magnetic flux density of the rotor core 8 on the rotor side using the steel sheet is about 1.8 stellas. Therefore, compared to conventional silicon steel sheets, 2.
The magnetic flux amount corresponding to 1−1.8 = 0.3 stellar can be effectively used.

From another viewpoint, another feature of the present invention is that the magnetic saturation magnetic flux density of the rotor
It can be said that there is a knowledge that holding down to as low as the residual magnetic flux density leads to an improvement in the torque performance of the permanent magnet rotating electric machine. In the rotary electric machine 1 of the present embodiment, the number of slots 43 of the stator core 4 is 24, and the number of slots per phase for each pole is 1 for 8 poles of the permanent magnet 6 of the rotor 3. However, the same effect as in the present embodiment can be obtained even with a rotating electric machine in which the number of slots per pole and each phase is increased to two or three.

FIG. 4 is a radial vertical sectional view showing a permanent magnet rotating electric machine according to another embodiment of the present invention. 1 denote the same components. In the figure, the second
The rotary electric machine 1 of the embodiment includes a stator 2 and a rotor 3. The structure of the stator 2 of this embodiment is a concentrated winding stator structure. Then, the stator 2 includes a stator yoke 42
And a stator core 4 comprising salient poles 44 and a stator winding 5 wound around the salient poles 44. Note that a slot portion 43 is formed between the salient pole portions 44.

On the other hand, the rotor 3 has a rotor structure in which an eight-pole permanent magnet 6 is provided inside, and includes a rotor core 8 and a shaft 9 inserted into the rotor core 8. I have. The permanent magnets 6 are arranged densely on the outer periphery of the rotor core 8. The rotor core 8 of the rotor 3 includes a yoke 81, a salient pole 82, a bridge 83, and a pole piece.
The configuration divided into 84 and the outer peripheral surface 85 is the same as that of the rotor core 8 of the first embodiment in FIG. 1, and the description thereof is omitted. Also in the structure of the rotor 3 in which the magnets are densely arranged as in the present embodiment, the magnetic flux emitted from the permanent magnet 6 passes through the bridge 83 from the salient pole 82 to the yoke 81 side, or to the other side. The configuration of the rotating electric machine 1 according to the present embodiment is characterized by the following points, since the leakage occurs to the pole side.

That is, the stator core 4 and the rotor core 8 of the rotary electric machine 1 of the present embodiment both use steel plates. The permanent magnet 6 uses a neodymium magnet. Then, for example, an impact force is applied to the bridge 83 of the rotor core 8 (including the bridge local near the bridge 83) to generate an internal stress at the local. It is a well-known technique that when a semi-permanent internal stress is generated by applying a mechanical stress, the local magnetic permeability at which the internal stress is generated can be reduced. Accordingly, when the same material is used for the stator core 4 and the rotor core 8, such a bridge local machining method is employed to reduce the magnetic permeability of the bridge (or the bridge local), and to reduce the magnetic permeability of the present invention. It is desirable to have a characteristic configuration. As a method of applying the mechanical stress, a method of simultaneously applying the mechanical stress at the time of punching the rotor core 8 is efficient and good. In particular, if the magnets of the present embodiment are arranged densely, the local portion of the bridge is a narrow and small area, so even with simple processing such as the simultaneous punching and impact processing as described above, it is ensured. There is an advantage that a low magnetic permeability can be obtained.

As in the above embodiment, the bridge 83 of the rotor core 8 is configured to have a lower magnetic permeability than that of the stator core 4. To reduce the magnetic flux leaking in the
In addition to the fact that the amount of magnetic flux can be effectively used, the mechanical strength of the rotor can be secured by the rotor core 8 made of a steel plate. An electric machine can be provided.

In the second embodiment, the bridge local machining method for locally lowering the magnetic permeability of the bridge 83 is adopted. However, the rotor core and the fixed core are similar to those of the embodiment shown in FIG. It is also possible to employ a combination of magnetic materials of the iron core in the configuration of the second embodiment. Further, even with such a configuration corresponding to the second embodiment in which a material having a lower magnetic saturation magnetic flux density than that of the stator core is used for the rotor core, the amount of magnetic flux of the permanent magnet is effectively used, It is possible to provide a permanent magnet rotating electric machine that secures strength, withstands high-speed rotation, and improves torque performance.

Although the rotary electric machine of the above embodiment has been described with respect to a rotary electric machine having an axial gap, the present invention provides
The present invention can be applied to any type of generator, electric motor, and motors of the internal rotation type, the external rotation type, and the linear type, and the stator structure regardless of the concentrated winding structure and the distributed winding structure. Furthermore, the present invention can be applied to a reluctance motor in which the outer peripheral portion of the rotor is connected via a bridge, exhibiting the same effects as those of the present invention.

Next, an electric vehicle using the permanent magnet rotating electric machine according to the present invention will be described. FIG. 5 is a schematic diagram showing an electric vehicle of one embodiment using a permanent magnet rotating electric machine according to the present invention. An electric vehicle according to the present embodiment as an electric vehicle shown in FIG. 5 includes an automobile body 101, a battery 102 for supplying DC power, a control device 103 for controlling DC power supplied to a permanent magnet rotating electric machine 104, It includes a permanent magnet rotating electric machine 104 to which the present invention is applied, and wheels 105 driven to travel by the permanent magnet rotating electric machine 104.

Then, the permanent magnet rotating electric machine 104 of this embodiment
The material of the stator core 4 of the stator 2 is a silicon steel plate, and the material of the rotor core 8 of the rotor 3 is a stainless steel plate having magnetic properties (permeability is about 1.0 stellar). Since the magnetic permeability of the stainless steel plate is lower than that of the silicon steel plate (the magnetic saturation magnetic flux density can be reduced), the torque performance of the permanent magnet rotating electric machine 104 can be improved by the same operation as described above. it can. At the same time, since a stainless steel plate known as a high-strength material is used for the rotor core 8, high-speed rotation can be handled.

The permanent magnet rotating electric machine 104 having the above-described structure can be rotated at a high speed to reduce the size of the rotating electric machine itself in size and weight, and also enables an electric vehicle employing the permanent magnet rotating electric machine 104 to run at a high speed. In other words, the adoption of a stainless steel plate having a magnetic permeability lower than that of a silicon steel plate and a large mechanical strength for the rotor core of the permanent magnet rotating electric machine for electric vehicles achieves a reduction in size and weight by high-speed rotation. In addition, it is possible to obtain an electric vehicle that is compatible with improved torque performance.

As described above, if the permanent magnet rotating electric machine according to the present invention is applied to an electric vehicle, particularly to an electric vehicle, it is possible to mount an electric drive device using a small, lightweight and high-efficiency permanent magnet rotating electric machine. This leads to the reduction in size and weight of vehicles, higher speeds, and improved economics. For example, as an improvement in economy, an electric vehicle or the like having a long travel distance per charge can be provided. Further, it is possible to provide an electric vehicle that leads to an improvement in safety.

[0029]

According to the present invention, it is possible to provide a permanent magnet rotating electric machine that can be rotated at high speed to be compact and lightweight, and that can obtain high torque. Further, if the electric vehicle uses the permanent magnet rotating electric machine of the present invention, the size and weight can be reduced.
This has the effect that it can be linked to higher speed running and improved economic efficiency.

[Brief description of the drawings]

FIG. 1 is a radial vertical sectional view showing a permanent magnet rotating electric machine according to an embodiment of the present invention.

FIG. 2 is an axial cross-sectional view showing a permanent magnet rotating electric machine according to one embodiment of the present invention.

FIG. 3 is a diagram showing a state of magnetic saturation magnetic flux density of a stator core and a rotor core of one embodiment of the permanent magnet rotating electric machine according to the present invention.

FIG. 4 is a radial vertical sectional view showing a permanent magnet rotating electric machine according to another embodiment of the present invention.

FIG. 5 is a schematic view showing an electric vehicle of one embodiment using a permanent magnet rotating electric machine according to the present invention.

[Explanation of symbols]

1 ... permanent magnet rotating electric machine, 2 ... stator, 3 ... rotor, 4 ...
Stator core, 5: stator winding, 6: permanent magnet, 7: permanent magnet insertion hole, 8: rotor core, 9: shaft, 10: housing, 11: end bracket, 12: bearing, 41 ...
Tooth, 42: stator yoke, 43: slot, 44: salient pole, 81: yoke, 82: auxiliary magnetic pole (salient pole), 83: bridge,
84: magnetic pole piece, 85: outer peripheral surface, 101: automobile body, 102: battery, 103: control device, 104: permanent magnet rotating electric machine, 105
... wheels, E ... encoder, PS ... magnetic pole position detector.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Suetaro Shibukawa 2520 Oji Takaba, Hitachinaka-shi, Ibaraki Co., Ltd.Automotive Equipment Division, Hitachi, Ltd. (72) Inventor Osamu Koizumi 2520 Odaiba-Koba, Hitachinaka-shi, Ibaraki Co., Ltd. Hitachi, Ltd. Automotive Equipment Division

Claims (4)

[Claims] A stator having a stator core and a stator winding wound around the stator core; and a rotor having a rotor core and a permanent magnet disposed in the rotor core. In the permanent magnet rotating electric machine, the magnetic permeability of the rotor core in an operating state of the permanent magnet rotating electric machine is lower than the magnetic permeability of the stator core. 2. The permanent magnet rotating electric machine according to claim 1, wherein said rotor core has a strength higher than a mechanical strength of said stator core. 3. The permanent magnet rotating electric machine according to claim 1, wherein the rotor core has a bridge in which a mechanical stress is applied in advance to reduce the magnetic permeability. 4. An electric vehicle using the permanent magnet rotating electric machine according to claim 1 for driving the electric vehicle.