JPH0469024A - Motor - Google Patents

Abstract

PURPOSE:To eliminate adverse influence of higher harmonic components, to reduce noise and vibration and to prevent deterioration of operational characteristics or increase of installation space by employing low magnetostriction material at the opposite ends in the axial direction of a laminated stator core and mounting a magnetic wedge in a slot. CONSTITUTION:Higher harmonic magnetic flux induced in a stator winding 4 by the higher harmonic components of current has tendency to concentrate at the opposite ends in the axial direction of a stator core 3 and the opposite ends in the axial direction of a rotor core 8 and thereby the higher harmonic magnetic flux passing through cores 12, 13 scarcely cause magnetostriction. Magnetic wedges 18, 19 mounted in a slot section suppress leakage of higher harmonic magnetic flux from the stator core 3 thus suppressing higher harmonic components of current induced in a rotor conductor 9 and reducing electromagnetic noise. Intermediate part of the stator core 3 is constituted of laminated core 14 and the central part of the rotor core 8 is constituted of laminated core 15.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to an electric motor driven by a non-sinusoidal power source, such as an inverter.

(Prior Art) When operating an electric motor, such as an induction motor, at variable speed, the power supply voltage and frequency may be variably controlled by an inverter. However, when the electric motor is driven by the above-mentioned inverter, there is a problem in that noise or vibration becomes larger than when the electric motor is driven by a commercial AC power source. Investigating the cause of this, we found that while the voltage and current waveforms output from commercial AC power supplies are sine waves, the voltage and current waveforms output from the inverters mentioned above are non-sinusoidal. In addition to the fundamental frequency component in the frequency domain (3 to 80H2), it contains a relatively large number of harmonic components. When an electric motor is driven by such an inverter, harmonic components generate harmonic magnetic flux in the windings, and this harmonic magnetic flux causes magnetostriction in the stator core and rotor core, resulting in increased noise or vibration. Ta.

In order to reduce such electromagnetic noise, conventionally, an inductance is inserted between the motor and the inverter to smooth the current flowing through the motor windings and reduce the harmonics of the fundamental frequency component contained in the current. The ratio of wave components is reduced, thereby reducing electromagnetic noise.

(Problem to be solved by the invention) However, in the conventional configuration described above, since an inductance is inserted between the motor and the inverter, it is not only the harmonic components contained in the current flowing through the motor windings, but also the fundamental components of the commercial frequency domain. Frequency components also decrease. For this reason, there was a problem in that operating characteristics such as power factor or starting torque deteriorated. Furthermore, since an inductance is required separately, there is also the problem that the installation space becomes large.

Therefore, an object of the present invention is to provide an electric motor that can prevent the adverse effects of harmonic components when driven by a non-sinusoidal power source, achieve low noise and low vibration, and prevent deterioration of operating characteristics and increase in installation space. It is on offer.

[Structure of the Invention] (Means for Solving the Problems) In the electric motor of the present invention, in the stator laminated core, the parts located at both ends in the axial direction are made of a low magnetostrictive material, and the other parts are made of a normal material. It is characterized in that it is constructed from a laminated core, and magnetic wedges are attached to slot portions of low magnetostrictive material located at both ends of the laminated core in the axial direction. In addition, in the stator laminated core, the parts located at both ends in the axial direction are made of a low magnetostrictive material, and the other parts are made of a normal laminated core, and furthermore, the parts located at both ends of the core are made of a low magnetostrictive material. The feature is that a ring-shaped magnetic material is arranged on the inner diameter side (gap side) of the ring.

(Function) According to experimental facts, the harmonic magnetic flux produced by the harmonic current flowing through the windings of the motor tends to concentrate at both ends of the laminated core in the axial direction. Therefore, according to the above means, even if the electric motor is driven by the inverter and a current containing many harmonic components flows through the windings, the harmonic magnetic flux caused by the current is transmitted to the magnetic flux located at both axial ends of the laminated iron core. Since magnetostriction occurs in the magnetostrictive material, the magnetostriction produced in the laminated iron core by the harmonic magnetic flux is reduced. On the other hand, since the central part of the laminated core, which is the part other than the low magnetostrictive material, is a normal laminated core, magnetic flux due to the fundamental wave component current can be generated in the part of the normal laminated core, and the low magnetostrictive material Even if there is, saturation of the main magnetic flux can be avoided, thereby preventing deterioration of operating characteristics. Further, since external attachment to the electric motor does not require a separate device, it is possible to prevent the installation space from becoming large.

(Example) An example of the present invention will be described below with reference to FIG. In FIG. 1, 1 is a frame, and 2 is a stator disposed inside the frame 1. In FIG. This stator 2
consists of a stator core 3, which is a laminated core, and a stator winding 4. A plurality of slots 5 are formed inside the stator core 3, and the stator winding 4 is wound within the slots 5. On the other hand, 6 is a rotor rotatably provided inside the stator 2, which is composed of a rotor shaft 71, a rotor iron core 8, and a rotor conductor 9. A plurality of slots 10 are formed in the outer periphery of the rotor core 8, and the rotor conductors 9 are provided in the slots 10.
Or installed.

Note that 11 is an end ring, which is attached to both ends of the rotor core 8.

The stator core 3 is composed of laminated cores 12 and 13 in which a low magnetostrictive material (for example, an iron plate containing 6.5% silicon) is laminated at both ends in the axial direction. An intermediate portion of the stator core 3 other than the portions located at both ends is constituted by a normal laminated core 14. This normal laminated iron core 14 is made by laminating low-silicon steel plates, such as iron plates containing less than 3.5% silicon, pure iron plates, or cold-rolled iron plates, either singly or in combination.

Further, the rotor core 8 is constituted by a normal laminated core 15. This normal laminated iron core 15 is formed by laminating low-silicon steel plates, such as iron plates containing 3.5% or less silicon, or cold-rolled iron plates singly or in combination. Furthermore, magnetic wedges 1 are inserted into the slot portions 16 and 17 of the laminated cores 12 and 13, which are laminated with low magnetostrictive iron plates (for example, 6°5% silicon-containing iron plates) located at both ends of the stator core 3.
8°19 is installed.

Next, the operation of the above configuration will be explained. When the above-mentioned motor is driven by an inverter, the current flowing through the stator winding 4 has a fundamental wave component (for example, 50 Hz).

(low frequency such as 60Hz) and harmonic components (such as 1kHz)
, 2kHz, etc.).

According to experimental facts, the harmonic magnetic flux generated in the stator winding 4 due to the harmonic components of the current is concentrated at both axial ends of the stator core 3 and at both axial ends of the rotor core 8. There is a tendency to In this case, since the portions of the stator core 3 located at both ends in the axial direction are composed of the laminated cores 12 and 13 in which low magnetostrictive iron plates are laminated, the harmonic magnetic flux passes through these cores 12 and 13. magnetostriction hardly occurs even when Therefore, electromagnetic noise can be reduced, and noise or vibration can be reduced. Furthermore, since the magnetic wedges 18 and 19 are attached to the slot portions, leakage of harmonic magnetic flux from the stator core 3 can be reduced, and harmonic components of the current induced in the rotor conductor 9 can also be reduced. and its electromagnetic noise can be reduced. On the other hand, the fundamental wave magnetic flux generated in the stator winding 4 by the fundamental wave component of the current flowing through the stator winding 4 is generated by the rotation Child core 8
Since the central portion of the core 14 is constituted by a normal laminated core 15, the magnetic resistance when the fundamental wave magnetic flux passes through these laminated cores 14 and 17 is small, and the loss is also small.

In this way, noise can be reduced in this embodiment.

If the stator core is constructed by laminating only low magnetostrictive iron plates, it is possible to reduce electromagnetic noise due to harmonic magnetic flux, but the saturation characteristics of the magnetic flux density will deteriorate, so the excitation current will increase. This has the disadvantage of increasing manufacturing costs.

According to this embodiment having such a configuration, in order to reduce electromagnetic noise due to harmonic magnetic flux during inverter driving, the portions of the stator core 3 located at both ends in the axial direction are made of an iron core laminated with a low magnetostrictive material. 12 and 13, and only the slots in the low magnetostriction material part are equipped with magnetic wedges, so compared to the conventional method in which an inductance is inserted, the basics of the commercial frequency range of the current flowing through the stator winding 4 are reduced. Deterioration of driving characteristics can be prevented without reducing frequency components. Further, since there is no need for a separate external device such as an inductance, the installation space can be reduced.

In the above embodiment, a laminated iron core 12.13 in which iron plates containing 6.5% silicon were laminated was used as a low magnetostrictive material, but the material is not limited to this, and a plastic material mixed with iron powder was used as a low magnetostrictive material. A molded body may also be used. Also,
Although the present invention has been applied to an inner rotor type in which the rotor 6 is rotated inside the stator 2, it may also be applied to an outer rotor type in which the rotor is rotated outside the stator.

Further, in the above embodiment, the magnetic wedge is attached only to the slot portion of the low magnetostrictive material portion, but the magnetic wedge may also be attached to the slot portion of the normal iron core portion.

(Other Embodiments) Hereinafter, other embodiments of the present invention will be described with reference to FIG.

In FIG. 2, 1 is a frame, and 2 is a stator disposed inside the frame 1. In FIG. The stator 2 includes a stator core 3, which is a laminated core, and a stator winding 4. A plurality of slots 5 are formed inside the stator core 3, and the stator winding 4 is wound within the slots 5. On the other hand, 6 is a rotor rotatably provided inside the stator 2, and this is a rotor shaft 7. It consists of a rotor core 8, which is a laminated core, and a rotor conductor 9. A plurality of slots 10 are provided on the outer circumference of the rotor core 8.
is formed, and the rotor conductor 9 is installed in this slot 10. Note that 11 is an end ring, which is attached to both ends of the rotor core 8.

Now, the stator core 3 is composed of laminated cores 12 and 13 in which portions located at both ends in the axial direction are laminated with low magnetostrictive iron plates (for example, 6.5% silicon-containing iron plates) made of a low magnetostriction material. There is. An intermediate portion of the stator core 3 other than the above-mentioned both ends is constituted by a normal laminated core 14. This normal laminated iron core 14 is formed by laminating low-silicon iron plates, such as iron plates containing 3.5% or less silicon, pure iron plates, or cold-rolled steel plates, either singly or in combination.

Further, the rotor core 8 is constituted by a normal laminated core 15. This normal laminated iron core 15 is formed by laminating low-silicon steel plates such as 3.596 or less silicon-containing iron plates, pure iron plates, or cold-rolled iron plates singly or in combination. Furthermore, the inner diameter side (gap side) portions 2 of the laminated cores 12 and 13, which are laminated with low magnetostrictive iron plates (for example, 6.5% silicon-containing iron plates) located at both ends of the stator core 3.
A magnetic ring 22.23 is placed at 0.21.

Next, the operation of the above configuration will be explained. When the above-mentioned motor is driven by an inverter, the current flowing through the stator winding 4 has a fundamental wave component (for example, 50 Hz).

(low frequency such as 60Hz) and harmonic components (such as 1kHz)
, 2kHz, etc.) are included.

According to experimental facts, the harmonic magnetic flux generated in the stator winding 4 by the harmonic components of the current is concentrated at both axial ends of the stator core 3 and at both axial ends of the rotary core 8. It has a nature. In this case, since the portions of the stator core 3 located at both ends in the axial direction are composed of the laminated cores 12 and 13 in which low-magnetostrictive iron plates are laminated, the harmonic magnetic flux is transmitted to these laminated cores 12 and 13. There is almost no magnetostriction even when passing through the tube. Therefore, electromagnetic noise can be reduced, and noise or vibration can be reduced. Furthermore, the magnetic ring 2 is attached to the inner diameter side (gap side) portion 20 and 21 of the stator core 3.
2.23 is arranged, it is possible to reduce the leakage of harmonic magnetic flux from the stator core 3, and the harmonic components of the current induced in the rotor conductor 9 are also reduced, reducing the electromagnetic noise. Can be reduced. On the other hand, the fundamental wave magnetic flux generated in the stator winding 4 by the fundamental wave component of the current flowing through the stator winding 4 is composed of the intermediate portion of the stator core 3 or the normal laminated core 14, and the rotating Since the child core 8 is constituted by a normal laminated core 15, the magnetic resistance when the fundamental wave magnetic flux passes through these laminated cores 14 and 15 is small, and therefore the loss is also small.

In this way, other embodiments of the present invention similarly reduce electromagnetic noise due to harmonic magnetic flux when driving an inverter.
Portions of the stator core 3 located at both ends in the axial direction are composed of laminated cores 12 and 13 made of laminated low magnetostrictive iron plates, and a portion 20.2 on the inner diameter side (gap side) of the low magnetostrictive material portion.
1, the fundamental frequency component of the current flowing through the stator winding 4 in the commercial frequency range does not decrease compared to the conventional structure in which an inductance is inserted. Deterioration of characteristics can be prevented. Further, since there is no need for a separate external device such as an inductance, the installation space can be reduced.

In the above embodiment, a laminated iron core 12°13 in which iron plates containing 6°5% silicon were laminated was used as a low magnetostrictive material, but the core is not limited to this, and iron powder may be mixed as a low magnetostrictive material. A plastic mold body may also be used. Further, although the present invention has been applied to an inner rotor type in which the rotor 6 is rotated inside the stator 2, it may be applied to an outer rotor type in which the rotor is rotated outside the stator. Furthermore, it is possible to use a material with high magnetic permeability or a material with low magnetostriction for the magnetic ring.

Also, a modification is shown in FIG. 3, where the inner diameter side (gap side) portion 20.
It is also possible to make the gap dimensions the same by increasing the outer diameter of 21 and arranging magnetic rings 22, 23 there.

Furthermore, in contrast to the embodiment of the present invention (FIG. 1), as shown in FIG. , it is possible to reduce noise due to harmonic components within the rotor laminated core 8, and such a configuration may be applied. In this case, the conductive layers 24 and 25 can be formed by any method such as thermal spraying of copper or aluminum, plating, or the like.

Similarly, for the modification of the present invention (FIG. 3), as shown in FIG. This makes it possible to reduce noise due to harmonic components within the rotor laminated core 8, and this configuration may be applied.

[Effects of the Invention] As is clear from the above description, the present invention can prevent the adverse effects of harmonic components when driven by a non-sinusoidal power source, achieve low noise and vibration, and improve the operating characteristics. This has an excellent effect of preventing deterioration and increasing the installation space.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a main part of an electric motor showing an embodiment of the present invention;
2 to 5 are views corresponding to FIG. 1 showing other embodiments of the present invention.

Claims (2)

[Claims] (1) An electric motor having a stator laminated core made of laminated electrical iron plates, characterized in that a low magnetostrictive material is provided at both ends of the core, and a magnetic wedge is attached to a slot portion of the low magnetostrictive material. . (2) The electric motor according to claim 1, wherein a ring-shaped magnetic material is disposed on the inner diameter side (gap side) of the low magnetostrictive material.