CN115118023A - Method for increasing leakage reactance of cage type asynchronous motor rotor end ring - Google Patents

Method for increasing leakage reactance of cage type asynchronous motor rotor end ring Download PDF

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Publication number
CN115118023A
CN115118023A CN202210765589.9A CN202210765589A CN115118023A CN 115118023 A CN115118023 A CN 115118023A CN 202210765589 A CN202210765589 A CN 202210765589A CN 115118023 A CN115118023 A CN 115118023A
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China
Prior art keywords
end ring
rotor
leakage
ferromagnetic material
asynchronous motor
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CN202210765589.9A
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Chinese (zh)
Inventor
王榕生
赖联锋
颜桂炀
宁世超
梁国祥
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Ningde Normal University
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Ningde Normal University
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    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02K—DYNAMO-ELECTRIC MACHINES
    • H02K1/00—Details of the magnetic circuit
    • H02K1/02—Details of the magnetic circuit characterised by the magnetic material
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02K—DYNAMO-ELECTRIC MACHINES
    • H02K1/00—Details of the magnetic circuit
    • H02K1/06—Details of the magnetic circuit characterised by the shape, form or construction
    • H02K1/22—Rotating parts of the magnetic circuit
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02K—DYNAMO-ELECTRIC MACHINES
    • H02K17/00—Asynchronous induction motors; Asynchronous induction generators
    • H02K17/02—Asynchronous induction motors
    • H02K17/16—Asynchronous induction motors having rotors with internally short-circuited windings, e.g. cage rotors
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02K—DYNAMO-ELECTRIC MACHINES
    • H02K2213/00—Specific aspects, not otherwise provided for and not covered by codes H02K2201/00 - H02K2211/00
    • H02K2213/03—Machines characterised by numerical values, ranges, mathematical expressions or similar information
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E10/00—Energy generation through renewable energy sources
    • Y02E10/70—Wind energy
    • Y02E10/72—Wind turbines with rotation axis in wind direction

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Induction Machinery (AREA)

Abstract

The invention relates to a method for increasing leakage reactance of an end ring of a cage type asynchronous motor rotor, which comprises the following steps: and a ferromagnetic material wrapping layer wraps the outer surface of the rotor end ring and provides a closed magnetic circuit with high magnetic permeability for a leakage magnetic field generated by the current of the end ring. The invention adopts a method for increasing the leakage reactance of the rotor end ring and reducing the starting current of an asynchronous motor, and the basic idea is that a layer of ferromagnetic material is wrapped on the surface of the rotor end ring, the ferromagnetic material provides a closed magnetic circuit with high magnetic permeability for a leakage magnetic field generated by the end ring current, so that the value of the leakage magnetic field interlinked with the end ring current is obviously enhanced, the leakage reactance value of the rotor end ring of the asynchronous motor is obviously improved, and the skin effect is generated to correspondingly increase the resistance of the end ring. Because the end ring leakage reactance is a component of the asynchronous motor rotor leakage reactance, the increase of the end ring leakage reactance value increases the rotor leakage reactance value, and the starting current of the asynchronous motor is necessarily reduced along with the increase of the end ring leakage reactance value.

Description

Method for increasing leakage reactance of cage type asynchronous motor rotor end ring
Technical Field
The invention relates to a method for increasing leakage reactance of an end ring of a cage type asynchronous motor rotor, and relates to the technical field of asynchronous motors.
Background
In order to reduce the starting current of the asynchronous motor, the current method mainly adopts a rotor deep groove or double-cage groove structure, and a current skin effect is generated through the structure, so that the starting resistance of the rotor is increased, and the double effects of reducing the starting current and increasing the starting torque are achieved. However, for an asynchronous motor seeking an ultra-high efficiency index, it is generally required to enlarge the rotor slot sectional area as much as possible to reduce the rotor resistance. However, the negative effect of increasing the starting current is brought by reducing the resistance of the rotor, and the overlarge starting current generates great impact on the power grid, thereby influencing the safe operation of the power grid. This problem is difficult to solve with "deep slot" or "double cage slot" configurations because increasing the lateral dimension of the rotor slots to increase the area tends to reduce the "skin" effect. For this reason, another new technical approach to reduce the starting current of the asynchronous motor is needed.
Disclosure of Invention
In view of the defects of the prior art, the technical problem to be solved by the invention is to provide a method for increasing the leakage reactance of the end ring of the rotor of the cage-type asynchronous motor.
In order to solve the technical problems, the technical scheme of the invention is as follows: a method for increasing the leakage resistance of a cage type asynchronous motor rotor end ring is provided, which comprises the following steps: and a ferromagnetic material wrapping layer wraps the outer surface of the rotor end ring and provides a closed magnetic circuit with high magnetic permeability for a leakage magnetic field generated by the current of the end ring.
Preferably, the ferromagnetic material wrapping layer wraps the outer surface of the end ring, which is in contact with air.
Preferably, the thickness of the ferromagnetic material wrapping layer is d, and the ferromagnetic material wrapping layer is tightly attached to the side surface of the iron core and forms a closed magnetic circuit of the end ring leakage magnetic field together with the rotor iron core.
Preferably, the thickness d of the wrapping layer of ferromagnetic material is 2 mm.
Preferably, the shape of the ferromagnetic material wrapping layer is adapted to the shape of the end ring, and a plurality of balance column holes for abdicating the balance column of the end ring and fan blade holes for abdicating the fan blades of the end ring are uniformly distributed on the circumference of the end side of the ferromagnetic material wrapping layer.
Compared with the prior art, the invention has the following beneficial effects: the invention adopts a method for increasing the leakage reactance of the rotor end ring and reducing the starting current of an asynchronous motor, and the basic idea is that a layer of ferromagnetic material is wrapped on the surface of the rotor end ring, the ferromagnetic material provides a closed magnetic circuit with high magnetic permeability for a leakage magnetic field generated by the end ring current, so that the value of the leakage magnetic field interlinked with the end ring current is obviously enhanced, the leakage reactance value of the rotor end ring of the asynchronous motor is obviously improved, and the skin effect is generated to correspondingly increase the resistance of the end ring. Because the end ring leakage reactance is a component of the asynchronous motor rotor leakage reactance, the improvement of the end ring leakage reactance value increases the whole rotor leakage reactance value, and the starting current of the asynchronous motor is necessarily reduced along with the increase of the end ring leakage reactance value. The leakage resistance of the end ring is obviously increased, the limitation of starting current on the increase of the section of the rotor slot can be eliminated, the efficiency of the motor is favorably improved, and the method is simple and easy to realize; the cost is low, the cost of the motor product is basically not increased, and the product competitiveness is favorably improved.
The present invention will be described in further detail with reference to the accompanying drawings and specific embodiments.
Drawings
Fig. 1 is a schematic diagram of a deep trench structure in the prior art.
Fig. 2 is a schematic diagram of a deep trench structure in the prior art.
Fig. 3 is a schematic diagram of a double cage groove structure in the prior art.
Fig. 4 is a front view of a shaftless cast aluminum rotor of the cage type asynchronous motor.
Fig. 5 is a side view of a cast aluminum rotor without a shaft for a cage type asynchronous motor.
FIG. 6 is a schematic configuration diagram of an embodiment of the present invention.
Fig. 7 is a schematic structural diagram of the ferromagnetic material wrapping layer.
Fig. 8 is a cross-sectional view a-B-C of fig. 7.
Fig. 9 is a schematic diagram of end-ring leakage field distribution.
FIG. 10 is a schematic diagram of the distribution of the end ring leakage magnetic field magnetic induction intensity B with the wrapping layer of ferromagnetic material.
FIG. 11 is a schematic diagram of the distribution of the end ring leakage magnetic field magnetic induction intensity B without the wrapping layer of ferromagnetic material.
In the figure: 1-rotor core, 2-rotor slot inner conductor, 3-slot magnetic leakage distribution, 4-rotor slot inner upper cage conductor, 5-rotor slot inner lower cage conductor, 6-end ring, 7-fan blade, 8-balance column, 9-ferromagnetic material wrapping layer, 10-ferromagnetic material magnetic circuit, 11-end ring magnetic leakage distribution, 12-balance column hole and 13-fan blade hole.
Detailed Description
The invention is further explained below with reference to the drawings and the embodiments.
It should be noted that the following detailed description is exemplary and is intended to provide further explanation of the disclosure. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs.
It is noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of example embodiments according to the present application. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, and it should be understood that when the terms "comprises" and/or "comprising" are used in this specification, they specify the presence of stated features, steps, operations, devices, components, and/or combinations thereof, unless the context clearly indicates otherwise.
As shown in fig. 1 to 11, the present embodiment provides a method for increasing leakage reactance of an end ring of a rotor of a cage-type asynchronous motor, where the method includes: and a ferromagnetic material wrapping layer wraps the outer surface of the rotor end ring and provides a closed magnetic circuit with high magnetic permeability for a leakage magnetic field generated by the current of the end ring.
In an embodiment of the invention, the ferromagnetic material wrapping layer wraps the outer surface of the end ring, which is in contact with air.
In the embodiment of the invention, the thickness of the ferromagnetic material wrapping layer is d, and the ferromagnetic material wrapping layer is tightly attached to the side surface of the iron core and forms a closed magnetic circuit of the end ring leakage magnetic field together with the rotor iron core.
In the embodiment of the present invention, the thickness d of the wrapping layer of ferromagnetic material should be increased according to the leakage reactance value, and is usually several millimeters. The thickness d of the wrapping layer of ferromagnetic material in this embodiment is taken to be 2 mm.
In the embodiment of the invention, the shape of the ferromagnetic material wrapping layer is matched with that of the end ring, the sizes of all parts of the ferromagnetic material wrapping layer are determined according to the size of the end ring, and the end ring ferromagnetic material wrapping layer is fixed on the end ring by riveting or the like. And a plurality of balance post holes for abdicating the end ring balance post and fan blade holes for abdicating the end ring fan blade are uniformly distributed on the circumference of the end side of the ferromagnetic material wrapping layer.
For a cage-type asynchronous motor, a rotor 'deep groove' or 'double cage groove' structure is adopted at present for reducing starting current, as shown in figures 1-3. Fig. 1 is a schematic diagram of a deep trench structure. The ratio of the groove depth h to the groove width b is typically greater than 10. When current is passed through the rotor bars, the slot leakage field is distributed as shown in fig. 1. It can be seen from the figure that the leakage flux of the current intersecting chain at the bottom of the conducting bar is much more than that of the current intersecting chain at the notch, so that the leakage reactance value presents the distribution characteristics of minimum top (at the notch) along the groove depth h direction and gradually increased along the groove depth direction, and the leakage reactance value at the bottom of the groove is maximum. At the time of starting the motor, since the rotor current frequency is high, the leakage resistance is large. The current distribution in the conductor depends on the leakage reactance distribution, and the current distribution and the leakage reactance distribution are approximately in inverse proportion, namely, the current is the minimum when the leakage reactance at the bottom of the slot is the maximum, and the current is the maximum when the leakage reactance at the position of the slot is the minimum, so that the current skin effect is formed. The effect is equivalent to reducing the effective height and cross-sectional area of the conducting bars, as shown in fig. 2, thereby increasing the rotor resistance at start-up and reducing the start-up current. Fig. 3 is a "double cage slot" shape, which increases rotor resistance and reduces starting current by the same mechanism as the deep slot structure.
However, to increase motor efficiency, it is often necessary to reduce rotor resistance, i.e., increase rotor slot area, and it is necessary to increase slot width b dimension. Because the conductor in the slot is made of non-ferromagnetic material, the magnetic resistance of the leakage magnetic flux is increased by increasing the slot width b, so that the leakage magnetic flux is weakened, the skin effect is reduced, the rotor resistance during starting cannot be effectively increased, and the starting current is reduced. Therefore, the method of 'deep groove' or 'double cage groove' is difficult to be applied to cage type asynchronous motors with ultra-high efficiency indexes.
Therefore, another idea is created in the scheme, and a method for increasing the leakage reactance of the end ring of the rotor and reducing the starting current of the asynchronous motor is provided. The method has the basic idea that a layer of ferromagnetic material is wrapped on the surface of the rotor end ring, and provides a closed magnetic circuit with high magnetic permeability for a leakage magnetic field generated by end ring current, so that the value of the leakage magnetic field interlinked with the end ring current is obviously enhanced, the leakage reactance value of the rotor end ring of the asynchronous motor is correspondingly and obviously improved, and the resistance of the end ring is correspondingly increased by generating a skin effect. Because the end ring leakage reactance is a component of the asynchronous motor rotor leakage reactance, the lifting of the end ring leakage reactance increases the rotor leakage reactance value, and the starting current of the asynchronous motor is necessarily reduced along with the rotor leakage reactance value. The method has the following advantages:
1. the method adopts ferromagnetic materials as media to construct a closed magnetic circuit for the end ring leakage magnetic field; the leakage resistance of the end ring is obviously increased, the limitation of starting current on the increase of the section of the rotor slot is eliminated, and the motor efficiency is favorably improved;
2. the leakage resistance of the end ring is obviously increased, so that the skin effect is generated to obviously increase the resistance of the end ring, and the starting torque of the motor is favorably improved;
3. the method is simple and easy to realize;
4. the cost is low, the cost of the motor product is basically not increased, and the product competitiveness is favorably improved.
Fig. 4-5 are structural diagrams of shaftless cast aluminum rotors of cage asynchronous motors. Cast aluminum end rings are arranged on two sides of the iron core, and fan blades, balance columns and other members are cast on the end rings.
Only one surface of the end ring is tightly attached to the side surface of the iron core, and the rest parts are all contacted with air. Therefore, the magnetic resistance of a magnetic circuit surrounding the end ring is large, so that the value of a leakage magnetic field generated by the current of the end ring is small, the corresponding leakage reactance value of the end ring is low, and the leakage reactance value of the whole rotor is only 3-6%. FIG. 6 shows a ferromagnetic materialThe end ring partial section of the wrapping layer is enlarged, and in order to increase the leakage magnetic field generated by the current of the end ring, the surface of the end ring is wrapped with a layer with the thickness ofdThe ferromagnetic material is closely attached to the side surface of the iron core, and forms a closed magnetic circuit of the end ring leakage magnetic field together with the rotor iron core. Because the magnetic path medium is a ferromagnetic material, the magnetic permeability of the magnetic path medium isμ Fe Much greater than that of non-ferromagnetic materialsμ 0 I.e. byμ Fe ＞＞μ 0 The value of the leakage flux at the end of the rotor passing through the magnetic circuit is obviously enhanced, so that the value of the leakage reactance at the end of the rotor is correspondingly increased, and the skin effect is generated, so that the resistance of the end ring is correspondingly increased. By adjusting the thicknessdThe end leakage flux value can be changed, i.e. increaseddThe end leakage flux value can be increased, and the rotor end leakage reactance value is correspondingly increased, and vice versa. Due to leakage reactance value and rotor current frequencyf 2 In proportion, when the motor finishes the starting process and the rotating speed is increased to the rated value,f 2 the leakage reactance value of the end part of the rotor is only 1-3 Hz, so that the leakage reactance value of the end part of the rotor is reduced sharply, the skin effect is eliminated, and the normal operation of the motor is not influenced.
The following simulation results are provided:
fig. 9 is a graph of an end ring leakage magnetic field profile. And (3) calculating the leakage magnetic field of the end ring of the Y90-4, 2.2kW asynchronous motor by adopting Ansoft software to obtain the numerical distribution of the magnetic induction intensity B of the leakage magnetic field under two conditions of an end ring wrapping layer and an end ring non-wrapping layer, wherein the numerical distribution is respectively shown in the graph of 10 and the graph of 11.
The ring current of the Y90-4, 2.2kW asynchronous motor is 466A at rated operation, and the starting current value is 6 times of the rated current, so that the current excitation of 2800A is applied to the end ring during simulation. Thickness of wrapping layerd=2mm。
FIG. 10 shows the simulation results for the case of the wrapping layer of ferromagnetic material of the end ring strip. As can be seen, the magnetic induction B at the point of the circle marked with m1 in the wrapping layer is 2.04T.
The wrapping layer ferromagnetic material is set to be a non-ferromagnetic material, and the end-ring leakage magnetic field distribution is solved for the model shown in fig. 9, so that the magnetic induction intensity B at m1 is reduced to 0.104T, as shown in fig. 11.
From the simulation results, it can be seen that after the ferromagnetic material wrapping layer is added to the end ring, the magnetic induction intensity B in the wrapping layer is increased by nearly 20 times. Although the space outside the wrapping layer also has a leakage magnetic field, the value of the leakage magnetic field attenuates with the increase of the distance, so the end ring leakage magnetic field mainly depends on the value of the magnetic field in the space inside the wrapping layer. Therefore, after the ferromagnetic material wrapping layer is added, the end ring leakage magnetic field is obviously increased. The leakage reactance of the end ring is in direct proportion to the value of the leakage magnetic field, so that the leakage reactance of the end ring and the skin effect generated by the leakage reactance of the end ring are correspondingly increased, and the starting current of the motor is reduced along with the increase of the leakage reactance of the end ring and the skin effect. The simulation result proves the effectiveness of the method.
The foregoing is directed to preferred embodiments of the present invention, other and further embodiments of the invention may be devised without departing from the basic scope thereof, and the scope thereof is determined by the claims that follow. However, any simple modification, equivalent change and modification of the above embodiments according to the technical essence of the present invention are within the protection scope of the technical solution of the present invention.

Claims (5)

1. A method for increasing the leakage reactance of an end ring of a cage type asynchronous motor rotor is characterized in that: the method comprises the following steps: and a ferromagnetic material wrapping layer wraps the outer surface of the rotor end ring and provides a closed magnetic circuit with high magnetic permeability for a leakage magnetic field generated by the current of the end ring.
2. The method for increasing the leakage resistance of the rotor end ring of the cage type asynchronous motor according to claim 1, is characterized in that: the ferromagnetic material wrapping layer wraps the outer surface, which is in contact with air, of the end ring.
3. The method for increasing the leakage resistance of the rotor end ring of the cage type asynchronous motor according to claim 1, is characterized in that: the thickness of the ferromagnetic material wrapping layer is d, the ferromagnetic material wrapping layer is tightly attached to the side face of the iron core, and the ferromagnetic material wrapping layer and the iron core form a closed magnetic circuit of the end ring leakage magnetic field.
4. The method for increasing the leakage resistance of the rotor end ring of the cage type asynchronous motor according to claim 3, is characterized in that: the thickness d of the ferromagnetic material wrapping layer is 2 mm.
5. The method for increasing the leakage resistance of the rotor end ring of the cage type asynchronous motor according to claim 1, is characterized in that: the shape of the ferromagnetic material wrapping layer is matched with that of the end ring, and a plurality of balance column holes used for abdicating the balance column of the end ring and fan blade holes used for abdicating the fan blades of the end ring are uniformly distributed on the circumference of the end side of the ferromagnetic material wrapping layer.
CN202210765589.9A 2022-07-01 2022-07-01 Method for increasing leakage reactance of cage type asynchronous motor rotor end ring Pending CN115118023A (en)

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CN202210765589.9A CN115118023A (en) 2022-07-01 2022-07-01 Method for increasing leakage reactance of cage type asynchronous motor rotor end ring

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CN202210765589.9A CN115118023A (en) 2022-07-01 2022-07-01 Method for increasing leakage reactance of cage type asynchronous motor rotor end ring

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN117318341A (en) * 2023-11-29 2023-12-29 山西电机制造有限公司 Cage rotor structure of three-phase asynchronous motor for reducing starting current and motor

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN117318341A (en) * 2023-11-29 2023-12-29 山西电机制造有限公司 Cage rotor structure of three-phase asynchronous motor for reducing starting current and motor
CN117318341B (en) * 2023-11-29 2024-03-22 山西电机制造有限公司 Cage rotor structure of three-phase asynchronous motor for reducing starting current and motor

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Inventor after: Wang Rongsheng

Inventor after: Liang Guoxiang

Inventor after: Lai Lianfeng

Inventor after: Yan Guiyang

Inventor after: Ning Shichao

Inventor before: Wang Rongsheng

Inventor before: Lai Lianfeng

Inventor before: Yan Guiyang

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Inventor before: Liang Guoxiang