CN209860683U - Rotor for asynchronous starting permanent magnet motor and asynchronous starting permanent magnet motor - Google Patents
Rotor for asynchronous starting permanent magnet motor and asynchronous starting permanent magnet motor Download PDFInfo
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- CN209860683U CN209860683U CN201921038798.3U CN201921038798U CN209860683U CN 209860683 U CN209860683 U CN 209860683U CN 201921038798 U CN201921038798 U CN 201921038798U CN 209860683 U CN209860683 U CN 209860683U
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Abstract
The utility model relates to a rotor and asynchronous starting permanent-magnet machine for asynchronous starting permanent-magnet machine, the rotor includes: the rotor comprises a rotating shaft, an iron core and a squirrel cage, wherein the rotating shaft penetrates through the center of the iron core, the squirrel cage is arranged on the periphery of the iron core, at least two poles of permanent magnets are embedded in the iron core, each pole of permanent magnet is provided with at least two layers of permanent magnets in the radial direction so as to at least comprise a first layer of permanent magnet and a second layer of permanent magnet, and the second layer of permanent magnet is arranged on the outer side, far away from the center o of the rotating shaft, of. Wherein, in a cross-section of the rotor, a total length L2 of the second layer of permanent magnets is in a range of 40% to 100% of a total length L1 of the first layer of permanent magnets. The waveform of the air gap flux density of the asynchronous starting permanent magnet motor comprising the rotor is closer to the ideal sine wave efficiency, and the efficiency and the performance of the motor are improved.
Description
Technical Field
The utility model relates to an asynchronous starting permanent-magnet machine field, more specifically relates to an asynchronous starting permanent-magnet machine's rotor that has double-deck permanent magnet.
Background
This section provides background information related to the present invention, which does not necessarily constitute prior art.
The asynchronous starting permanent magnet motor is a permanent magnet motor with self-starting capability and has the characteristics of an induction motor and a permanent magnet synchronous motor. The motor is started by means of asynchronous torque generated by interaction of a stator rotating magnetic field and a cage type rotor, and when the motor runs in a steady state, the rotating speed of the rotor is synchronous speed, the cage type rotor does not work any more, and rotor resistance loss does not exist. Compared with a speed-regulating permanent magnet motor, the rotor of the motor is provided with the squirrel cage bars, so that the self-starting under a certain voltage and frequency can be realized; compared with an electrically excited synchronous motor, the permanent magnet replaces an excitation winding, a collector ring closing electric brush is omitted, the structure is simpler, and the operation is more reliable. At present, the asynchronous starting permanent magnet motor can be used as a compressor for an air conditioner, a refrigerator, or a motor for driving a vehicle.
In the design of an asynchronous starting permanent magnet motor, the mode of arranging permanent magnets in a rotor directly influences the air gap flux, the leakage flux and the performance of the motor. Because the rotor structure of the asynchronous starting permanent magnet motor is too complex, which will increase the uncertainty of the motor design and the requirement for the production process, the common rotor structure at present is a structure of parallel, serial or mixed design of permanent magnets of two adjacent magnetic poles, wherein the permanent magnet of each magnetic pole is usually a single layer. However, the air gap flux density waveform and the electromotive force waveform of the current asynchronous starting permanent magnet synchronous motor contain more harmonic components, so that the motor efficiency is reduced.
Accordingly, there is a need for an improved asynchronous starting permanent magnet motor that reduces the harmonics present in the air gap flux and electromotive force waveforms and improves motor efficiency without unduly increasing the complexity of the rotor structure.
SUMMERY OF THE UTILITY MODEL
The general outline of the present invention is provided in this section, not a full scope of the invention or a full disclosure of all the features of the invention.
The utility model aims at providing a simple, reliable, efficient asynchronous starting permanent-magnet machine's rotor.
According to an aspect of the present invention, there is provided a rotor for an asynchronous starting permanent magnet motor, the rotor comprising: the rotor comprises a rotating shaft, an iron core and a squirrel cage, wherein the rotating shaft penetrates through the center of the iron core, the squirrel cage is arranged on the periphery of the iron core, at least two poles of permanent magnets are embedded in the iron core, each pole of permanent magnet is provided with at least two layers of permanent magnets in the radial direction so as to at least comprise a first layer of permanent magnet and a second layer of permanent magnet, and the second layer of permanent magnet is arranged on the outer side, far away from the center o of the rotating shaft, of. Wherein, in a cross-section of the rotor, a total length L2 of the second layer of permanent magnets is in a range of 40% to 100% of a total length L1 of the first layer of permanent magnets.
Optionally, in a cross-section of the rotor, a total length L2 of the second layer of permanent magnets is in a range of 80% to 95% of a total length L1 of the first layer of permanent magnets.
Alternatively, the rotor is a rotor of a two-pole configuration, and the air gap flux density of the rotor is less than or equal to 20% of the peak value when the rotation angle of the rotor is in the range of 0 ° to 20 ° and 160 ° to 180 ° for each pole.
Alternatively, the rotor is a rotor of a two-pole configuration, and the waveform of the air gap flux density of the rotor approaches a sinusoidal waveform when the rotation angle of the rotor is in the range of 20 ° to 160 ° for each pole.
Alternatively, the rotor is a two pole configuration rotor, the waveform of the air gap flux density of the rotor having at least two steps for each pole, with the highest step being a flat-topped curve.
Optionally, the first layer of permanent magnets is configured in a straight line shape, a V-shape, a U-shape or an arc shape, and the second layer of permanent magnets is configured in a straight line shape, a V-shape, a U-shape or an arc shape. Preferably, the first layer of permanent magnets is configured as a U-shaped permanent magnet group composed of three sections of permanent magnets, and the second layer of permanent magnets is also configured as a U-shaped permanent magnet group composed of three sections of permanent magnets.
Optionally, the rotor is a rotor of a four-pole configuration or a rotor of a multi-pole configuration with more than four poles.
Alternatively, each pole of the permanent magnet has a three-layer arrangement or a multi-layer arrangement of more than three layers in the radial direction.
According to another aspect of the present invention, there is also provided an asynchronous starting permanent magnet machine comprising a rotor as described hereinbefore.
Generally, according to the utility model discloses an asynchronous starting permanent magnet synchronous machine is through arranging the permanent magnet in the rotor into the bilayer and make one deck permanent magnet and two layers of permanent magnet satisfy certain dimensional relation, reduce the harmonic that contains in the harmonic that contains and the electromotive force wave form in the air gap magnetic flux density wave form for the sinusoidal wave form of air gap magnetic flux density's wave form is close the ideal more, thereby has increased asynchronous starting permanent magnet synchronous machine's torque, has improved asynchronous starting permanent magnet synchronous machine's efficiency.
Drawings
The foregoing and additional features and characteristics of the present invention will become more apparent from the following detailed description, taken with reference to the accompanying drawings, which are given by way of example only and which are not necessarily drawn to scale. Like reference numerals are used to indicate like parts in the accompanying drawings, in which:
fig. 1 is a cross-sectional view showing a rotor of a related art asynchronous starting permanent magnet synchronous motor in which a rotor core embeds a double-layered permanent magnet;
FIG. 2 illustrates a waveform of magnetomotive force of a rotor of the asynchronously-started permanent magnet synchronous electric machine of FIG. 1;
fig. 3a and 3b show cross-sectional views of a rotor and a rotor core, respectively, of an asynchronously started permanent magnet synchronous machine according to a first embodiment of the present invention;
FIG. 4 shows a waveform of the air gap flux density of the rotor of the asynchronously-started permanent magnet synchronous machine of FIG. 3 a;
fig. 5a and 5b show cross-sectional views of a rotor and a rotor core, respectively, of an asynchronously started permanent magnet synchronous machine according to a second embodiment of the present invention;
fig. 6a and 6b show cross-sectional views of a rotor and a rotor core, respectively, of an asynchronously started permanent magnet synchronous machine according to a third embodiment of the present invention;
fig. 7a and 7b show cross-sectional views of a rotor and a rotor core, respectively, of an asynchronously started permanent magnet synchronous machine according to a fourth embodiment of the present invention;
fig. 8 shows a cross-sectional view of a rotor and a rotor core of an asynchronous starting permanent magnet synchronous machine according to a fifth embodiment of the present invention, wherein a four-pole permanent magnet is built in the rotor core;
fig. 9 is a waveform comparison diagram showing electromotive forces of the rotor of the related art asynchronous starting permanent magnet synchronous motor in fig. 1 and the rotors of the asynchronous starting permanent magnet synchronous motors in the first to fourth embodiments of the present invention;
fig. 10 shows a histogram of electromotive harmonics of the rotor of the related art asynchronous starting permanent magnet synchronous machine in fig. 1 and the rotors of the asynchronous starting permanent magnet synchronous machines in the first to fourth embodiments of the present invention.
Detailed Description
A preferred embodiment of the present invention will now be described in detail with reference to fig. 1 to 10. The following description is merely exemplary in nature and is not intended to limit the present disclosure, application, or uses. Corresponding components or parts are designated by the same reference numerals throughout the several views.
Fig. 1 shows a rotor 10 of a related art asynchronous starting permanent magnet synchronous machine. As shown in fig. 1, the rotor 10 of the asynchronous starting permanent magnet synchronous motor mainly includes an iron core 50, a cage 30 disposed at an outer circumference of the iron core 50, and end rings 20 installed at both ends of the cage 30. The core 50 may be a laminated core having a through hole 53 provided at the center thereof for mounting the rotation shaft, grooves provided at the outer circumference thereof for mounting the aluminum bars of the cage 30, and slits provided between the through hole 53 and the grooves for inserting the permanent magnets 60. The permanent magnet 60 is configured in a two-pole structure including permanent magnets 601, 601 'constituting N poles and permanent magnets 602, 602' constituting S poles, each of which is arranged in two layers in a radial direction and each of the permanent magnets 601, 601', 602' is linear.
In the asynchronous starting permanent magnet synchronous motor, the electromagnetic torque is composed of a permanent magnet torque generated by interaction of a permanent magnet magnetic field and an armature reaction magnetic field and a reluctance torque caused by asymmetry of d-axis and q-axis magnetic circuits of the asynchronous starting permanent magnet synchronous motor, wherein a d axis is defined as a connecting line from a rotating shaft center o to the center of each pole permanent magnet in the circumferential direction, and a q axis is defined as a connecting line from the rotating shaft center o to the center between the two pole permanent magnets in the circumferential direction. Permanent magnets 601, 601 'and permanent magnets 602, 602' are arranged symmetrically about the q-axis in core 50 on both sides of the q-axis, and a second layer of permanent magnets 601 'is parallel to the first layer of permanent magnets 601 at intervals and a second layer of permanent magnets 602' is parallel to the first layer of permanent magnets 602 at intervals.
Fig. 2 shows a magnetomotive force waveform detected at a prescribed position (position marked by 0 °) of the rotor 10 in fig. 1, in which the vertical axis represents the magnetomotive force of the rotor 10 and the horizontal axis represents the rotation angle of the rotor. Assuming that the rotor 10 is rotated in the clockwise direction, the magnetomotive force is not detected until the permanent magnet 601 reaches the position shown in fig. 1.
As can be seen from fig. 2, when the rotor 10 starts to rotate, that is, the rotation angle of the rotor is in the vicinity of 0 °, the magnetomotive force of the permanent magnet 601 detected is small. As the rotor 10 rotates, the magnetomotive force formed by the permanent magnets 601 increases and reaches a first peak, and this state is maintained over a certain rotational angle, thereby forming a first step of the waveform. When the rotor 10 further rotates and the permanent magnet 601 'reaches the position marked by 0 deg., the detected magnetomotive force further increases and reaches the second peak due to the superposition of the magnetomotive force generated by the permanent magnet 601', and this state is maintained within a certain rotational angle, thereby forming the second step (i.e., the highest step) of the waveform. Subsequently, the detected magnetomotive force decreases from the second peak value to the first peak value, and then continues to decrease from the first peak value after being maintained within a certain rotation angle. When the rotor rotates to around 180 °, the detected magnetomotive force of the permanent magnet 601 is small. In this process, the rotor 10 is rotated 180 °, i.e., in the range of the rotation angle of the rotor from 0 ° to 180 °, the magnetomotive force is positive, constituting a half cycle of the magnetomotive force variation. Subsequently the rotor 10 continues to rotate, the wave form of the magnetomotive force formed by the permanent magnets 602, 602' is the same as and reversed from that of the magnetomotive force in the range of rotation angles 0 ° to 180 °, constituting the other half cycle of the magnetomotive force variation, at the rotation angle of the rotor in the range of 180 ° to 360 °. The rotor 10 is continuously rotated to generate a continuous magnetomotive force waveform.
In practical applications, magnetomotive force waveforms tend to appear substantially rectangular or V-shaped due to the presence of harmonics. In addition, the driving direction of the rotor is opposite due to magnetomotive force generated by the adjacent permanent magnets with different poles, and the electromagnetic torque of the rotor is reduced. Although the permanent magnet 60 is provided in a double-layer structure, so that the substantially rectangular magnetomotive force waveform is improved to a waveform having two steps, it is apparent that the magnetomotive force waveform exhibits a relatively drastic change due to the presence of harmonics, and particularly, the highest step almost exhibits a V-shape, which is greatly different from an ideal sinusoidal waveform. In this case, since the air-gap flux density is proportional to the magnetomotive force and has the same phase, the waveform of the air-gap flux density and the waveform of the electromotive force also include many harmonics, and the efficiency is reduced by the harmonics, and the rotor torque is reduced.
To the technical problem, the utility model discloses rotor structure to the asynchronous starting PMSM of correlation technique has improved, and is general, the utility model discloses a to arranging of permanent magnet in limited space improving, improved the output characteristic of motor. In particular, the rotor structure of an improved asynchronous starting permanent magnet synchronous machine according to several preferred embodiments of the present invention will be described in detail below with reference to fig. 3a to 8. In each embodiment, the main structures of the rotor, such as the cage 300, the end rings 200, and the core 500, are similar to those of the related art, and thus, a detailed description thereof is omitted.
Fig. 3a and 3b show cross-sectional views of a rotor 100 and a core 500, respectively, of an asynchronous starting permanent magnet synchronous machine according to a first embodiment of the present invention. Wherein, the iron core 500 is embedded with a permanent magnet 610. The permanent magnet 610 has a two-pole structure including permanent magnets 611, 611 'constituting an N pole and permanent magnets 612, 612' constituting an S pole, each of which is arranged in two layers in the radial direction. The permanent magnets 611, 611 'and the permanent magnets 612, 612' are symmetrically arranged on both sides of the q-axis with respect to the q-axis in the iron core 500, and the permanent magnets 611, 611 'and the permanent magnets 612, 612' are themselves symmetrical with respect to the d-axis. Wherein the first layer of permanent magnets 611, 612 are respectively configured as a linear permanent magnet, and the second layer of permanent magnets 611', 612' are respectively configured as a permanent magnet group composed of two sections of permanent magnets and arranged in a V-shape, and the second layer of permanent magnets 611', 612' are respectively disposed outside the first layer of permanent magnets 611, 612 away from the center of the rotation shaft. Further structural arrangements of permanent magnets and the air gap flux density waveforms generated by permanent magnets 612, 612 'forming the S-pole will now be described with reference to fig. 4, taking permanent magnets 612, 612' forming the S-pole as an example.
Further, in the cross-section of the rotor, the total length of the first layer of permanent magnets 612 is L1, and the total length of the two segments of permanent magnets of the second layer of permanent magnets 612' is L2, wherein the length L2 is in the range of 40% to 100% of the length L1. Preferably, length L2 is in the range of 60% to 100% of length L1. More preferably, length L2 is in the range of 80% to 95% of length L1. It should be noted that the numerical ranges of the present invention include the end points.
It is assumed that the rotor 100 rotates in a clockwise direction. When the rotor 100 is rotated from 0 to about 20, the first layer of permanent magnets 612 reaches the position labeled 0. Corresponding to fig. 4, when the rotation angle of the rotor 100 is in the range of 0 ° to 20 °, the air gap flux density of the rotor 100 is less than or equal to 20% of its peak value. As the rotor 100 rotates, the air-gap flux density increases and reaches a first peak, and this state is maintained for a certain rotation angle, thereby forming a first step of a waveform. When the rotor 100 further rotates and the second layer permanent magnet 612 'reaches the position marked by 0 °, the air gap flux density of the rotor 100 further increases and reaches the second peak due to the magnetic field generated by the overlapping second layer permanent magnet 612', and this state is maintained for a certain rotation angle, thereby forming the second step (i.e., the highest step) of the waveform. As the rotor 100 rotates further, when the second layer of permanent magnets 612' leaves the position marked at 0 °, the air gap flux density decreases from the second peak to the first peak, and then continues to decrease from the first peak after being maintained for a certain rotation angle. When the rotor 100 is rotated to approximately 160 deg., the first layer of permanent magnets 612 is displaced from the position marked 0 deg., shown in fig. 4 as the rotational angle of the rotor 100 is in the range of 160 deg. to 180 deg., the air gap flux density of the rotor 100 is small, less than or equal to 20% of its peak value.
In this process, the rotor 100 is rotated 180 °, that is, in the range where the rotation angle of the rotor 100 is 0 ° to 180 °, the air-gap flux density is positive, constituting a half cycle of the air-gap flux density waveform. Subsequently, the rotor 100 continues to rotate, and the waveform of the air gap flux density is inverted from that of the air gap flux density in the range of the rotation angle of 0 ° to 180 ° to constitute the other half cycle waveform when the rotation angle of the rotor is in the range of 180 ° to 360 °. The rotor 100 is rotated continuously to generate a continuous air gap flux density waveform.
As can be seen from fig. 4, the rotor according to the first embodiment of the present invention has an air gap flux density waveform containing fewer harmonics, and particularly, the highest step exhibits a relatively flat top curve rather than a V-shape. The air gap flux density is generally more closely waveshaped than the ideal sinusoidal waveform. Correspondingly, the electromotive force waveform of the rotor also contains fewer harmonics, so that the motor current is reduced, the motor efficiency is improved, and the torque performance of the motor is improved.
Fig. 5a and 5b show cross-sectional views of a rotor 100 and a core 500, respectively, of an asynchronously-started permanent magnet synchronous machine according to a second embodiment of the present invention. Wherein, the iron core 500 is embedded with a permanent magnet 620. The permanent magnet 620 has a two-pole structure including permanent magnets 621, 621 'constituting N poles and permanent magnets 622, 622' constituting S poles, each of which is arranged in two layers in the radial direction. The symmetrical design of the permanent magnets 621, 621 'and 622, 622' about the q-axis and d-axis is the same as that of the first embodiment of the present invention, and is not described in detail herein. The difference is that the first layer of permanent magnets 621, 622 are respectively configured as linear permanent magnets, and the second layer of permanent magnets 621', 622' are respectively configured as permanent magnet groups composed of three segments of permanent magnets and arranged in a U-shape. Wherein, in the cross section of the rotor, the total length L1 of the first layer permanent magnet 621 or 622 and the total length L2 of the three-segment permanent magnet of the second layer permanent magnet 621 'or 622' are both, wherein the length L2 is in the range of 40% to 100% of the length L1. Preferably, length L2 is in the range of 60% to 100% of length L1. More preferably, length L2 is in the range of 80% to 95% of length L1.
The air gap flux density waveform of the rotor in the second embodiment shows similar results to the rotor in the first embodiment. Taking a half cycle as an example, when the rotation angle of the rotor 100 is in the range of about 0 ° to 20 ° and 160 ° to 180 °, the air gap flux density of the rotor 100 is small, less than or equal to 20% of its peak value. When the rotation angle of the rotor 100 is in the range of 20 ° to 160 °, the air gap magnetic flux density increases and reaches a first peak as the rotor 100 rotates, and this state is maintained within a certain rotation angle, thereby forming a first step of a waveform; then the air gap flux density of the rotor 100 further increases and reaches the second peak, and the state is maintained for a certain rotation angle, thereby forming the second step (i.e., the highest step) of the waveform; then the air gap flux density is reduced from the second peak value to the first peak value, and is maintained within a certain rotation angle and then is continuously reduced from the first peak value.
According to the second embodiment of the present invention, the air gap flux density waveform contains fewer harmonics, especially the highest step presents a flatter top rather than a V-shape. The air gap flux density is generally more closely waveshaped than the ideal sinusoidal waveform. Correspondingly, the electromotive force waveform of the rotor also contains fewer harmonics, so that the motor current is reduced, the motor efficiency is improved, and the torque performance of the motor is improved.
Fig. 6a and 6b show cross-sectional views of a rotor 100 and a core 500, respectively, of an asynchronous starting permanent magnet synchronous machine according to a third embodiment of the present invention. Wherein, the iron core 500 is embedded with a permanent magnet 630. The permanent magnet 630 has a two-pole structure including permanent magnets 631 and 631 'constituting N poles and permanent magnets 632 and 632' constituting S poles. Each pole of permanent magnet is arranged in a double layer in the radial direction. The symmetrical design of the permanent magnets 631, 631 'and 632, 632' about the q-axis and d-axis is the same as in the first embodiment of the present invention, and is not described in detail herein. The difference is that the first layer permanent magnets 631, 632 are respectively configured as a permanent magnet group composed of three pieces of permanent magnets and arranged in a U shape, and the second layer permanent magnets 631', 632' are also respectively configured as a permanent magnet group composed of three pieces of permanent magnets and arranged in a U shape, the first layer permanent magnet 631 and the second layer permanent magnet 631 'are parallel to each other, and the first layer permanent magnet 632 and the second layer permanent magnet 632' are parallel to each other. Wherein, in the cross section of the rotor, the total length of the three permanent magnets of the first layer of permanent magnets 631 or 632 is L1, and the total length of the three permanent magnets of the second layer of permanent magnets 631 'or 632' is L2, wherein the length L2 is in the range of 40% to 100% of the length L1. Preferably, length L2 is in the range of 60% to 100% of length L1. More preferably, length L2 is in the range of 80% to 95% of length L1.
The air gap flux density waveform of the rotor in the third embodiment shows similar results to the rotor in the first embodiment. Taking a half cycle as an example, when the rotation angle of the rotor 100 is in the range of about 0 ° to 20 ° and 160 ° to 180 °, the air gap flux density of the rotor 100 is small, less than or equal to 20% of its peak value. When the rotation angle of the rotor 100 is in the range of 20 ° to 160 °, the air gap magnetic flux density increases and reaches a first peak as the rotor 100 rotates, and this state is maintained within a certain rotation angle, thereby forming a first step of a waveform; then the air gap flux density of the rotor 100 further increases and reaches the second peak, and the state is maintained for a certain rotation angle, thereby forming the second step (i.e., the highest step) of the waveform; then the air gap flux density is reduced from the second peak value to the first peak value, and is maintained within a certain rotation angle and then is continuously reduced from the first peak value.
According to the third embodiment of the present invention, the air gap flux density waveform contains fewer harmonics, and especially the highest step presents a flatter top rather than a V-shape. The air gap flux density is generally more closely waveshaped than the ideal sinusoidal waveform. Correspondingly, the electromotive force waveform of the rotor also contains fewer harmonics, so that the motor current is reduced, the motor efficiency is improved, and the torque performance of the motor is improved.
Fig. 7a and 7b show cross-sectional views of a rotor 100 and a core 500, respectively, of an asynchronous starting permanent magnet synchronous machine according to a fourth embodiment of the present invention. Wherein, the iron core 500 is embedded with a permanent magnet 640. The permanent magnet 640 has a two-pole structure including permanent magnets 641, 641 'constituting N poles and permanent magnets 642, 642' constituting S poles. Each pole of permanent magnet is arranged in a double layer in the radial direction. The symmetric design of the permanent magnets 641, 641 'and 642, 642' about the q-axis and the d-axis is the same as that of the first embodiment of the present invention, and is not repeated here. The difference is that the one-layer permanent magnets 641, 642 are respectively configured as arc-shaped permanent magnets, and the two-layer permanent magnets 641', 642' are also respectively configured as arc-shaped permanent magnet groups, the one-layer permanent magnet 641 and the two-layer permanent magnet 641 'being parallel to each other, and the one-layer permanent magnet 642 and the two-layer permanent magnet 642' being parallel to each other. In the cross section of the rotor, the total length of one layer of the permanent magnet 641 or 642 is L1 (in this case, the arc length), and the total length of the two layers of the permanent magnets 641 'or 642' is L2 (in this case, the arc length), wherein the length L2 is in the range of 40% to 100% of the length L1. Preferably, length L2 is in the range of 60% to 100% of length L1. More preferably, length L2 is in the range of 80% to 95% of length L1.
The air gap flux density waveform of the rotor in the fourth embodiment shows similar results to the rotor in the first embodiment. Taking a half cycle as an example, when the rotation angle of the rotor 100 is in the range of about 0 ° to 20 ° and 160 ° to 180 °, the air gap flux density of the rotor 100 is shown to be small, less than or equal to 20% of its peak value. When the rotation angle of the rotor 100 is in the range of 20 ° to 160 °, the air gap magnetic flux density increases and reaches a first peak as the rotor 100 rotates, and this state is maintained within a certain rotation angle, thereby forming a first step of a waveform; then the air gap flux density of the rotor 100 further increases and reaches the second peak, and the state is maintained for a certain rotation angle, thereby forming the second step (i.e., the highest step) of the waveform; then the air gap flux density is reduced from the second peak value to the first peak value, and is maintained within a certain rotation angle and then is continuously reduced from the first peak value.
According to the rotor of the fourth embodiment of the present invention, the air gap flux density waveform contains fewer harmonics, and particularly the highest step presents a flatter top rather than a V-shape. The air gap flux density is generally more closely waveshaped than the ideal sinusoidal waveform. Correspondingly, the electromotive force waveform of the rotor also contains fewer harmonics, so that the motor current is reduced, the motor efficiency is improved, and the torque performance of the motor is improved.
It should be understood by those skilled in the art that the arrangement of the double-layer permanent magnet in the rotor structure of the asynchronous starting permanent magnet synchronous motor of the present invention can be applied not only to a rotor having a two-stage structure, but also to a multi-pole rotor having four poles, six poles, or eight poles. The specific shape of one layer of permanent magnet and two layers of permanent magnets may be selected as desired, and may be configured, for example, as a linear permanent magnet, a group of permanent magnets consisting of two sections of permanent magnets and arranged in a V-shape, a group of permanent magnets consisting of three sections of permanent magnets and arranged in a U-shape, or an arc-shaped permanent magnet, and other permanent magnets of suitable shapes, as long as the total length of the two layers of permanent magnets is L2 in the range of 40% to 100%, preferably in the range of 60% to 100%, and more preferably in the range of 80% to 95% of the total length L1 of the one layer of permanent magnets. A schematic diagram of a four-pole rotor of an asynchronous starting permanent magnet synchronous machine and its core according to the present invention is shown in fig. 8, including permanent magnet arrangements that are linear, arc, V-shaped and U-shaped. Similar to the results shown by a two-pole rotor, the four-pole rotor adopting the permanent magnet arrangement also shows good effects that the air gap magnetic flux density waveform and the electromotive force waveform contain less harmonic waves, the air gap magnetic flux density waveform is closer to an ideal sinusoidal waveform, the motor current is reduced, the motor torque performance is improved, the motor efficiency is improved and the like.
Table 1 below shows the performance of the related art asynchronous starting permanent magnet synchronous motor having the rotor structure as shown in fig. 1 and 2 compared with the performance of the asynchronous starting permanent magnet synchronous motor having the rotor structure according to the first to third embodiments of the present invention.
TABLE 1
As can be seen from table 1, the current of the asynchronous starting permanent magnet synchronous motor having the rotor structure according to the first to third embodiments of the present invention is reduced, the efficiency is increased, and the maximum torque is increased, compared to the asynchronous starting permanent magnet synchronous motor of the related art. Particularly, the first layer of permanent magnets and the second layer of permanent magnets in the third embodiment are both U-shaped rotors, so that the working efficiency and the maximum torque are both remarkably improved, and the working performance is remarkably improved.
Fig. 9 is a graph showing a waveform comparison of an electromotive force of the asynchronous starting permanent magnet synchronous motor of the related art having the rotor structure as shown in fig. 1 and 2 and an electromotive force of the asynchronous starting permanent magnet synchronous motor having the rotor structure according to the first to third embodiments of the present invention. Fig. 10 shows a comparison graph of harmonics included in the waveform of the electromotive force in fig. 9 in the form of a histogram. As can be further seen from fig. 9 and 10, the electromotive force waveform of the asynchronous starting permanent magnet synchronous motor having the rotor structure according to the first to third embodiments of the present invention contains fewer harmonics, so that the loss due to the harmonics is less and the efficiency of the asynchronous starting permanent magnet synchronous motor is higher.
The working medium circulation system according to a preferred embodiment of the invention has been described above with reference to a specific embodiment. It will be understood that the above description is intended to be illustrative and not restrictive, and that various changes and modifications may be suggested to one skilled in the art in view of the above description without departing from the scope of the invention. Such variations and modifications are also intended to be included within the scope of the present invention.
Claims (10)
1. A rotor for an asynchronously started permanent magnet electric machine, the rotor comprising:
a rotating shaft;
the rotating shaft penetrates through the center of the iron core; and
a cage disposed at an outer circumferential portion of the core,
wherein the iron core is provided with at least two permanent magnets in an embedded manner, each permanent magnet has at least two layers of arrangement in the radial direction so as to at least comprise a first layer of permanent magnets and a second layer of permanent magnets, the second layer of permanent magnets are arranged on the outer side of the first layer of permanent magnets far away from the center o of the rotating shaft,
characterized in that, in a cross-section of the rotor, the total length L2 of the second layer of permanent magnets is in the range of 40% to 100% of the total length L1 of the first layer of permanent magnets.
2. The rotor for an asynchronously started permanent magnet electric machine of claim 1, the total length of the second layer of permanent magnets, L2, being in the range of 80% to 95% of the total length of the first layer of permanent magnets, L1, in a cross section of the rotor.
3. A rotor for an asynchronously started permanent magnet electric machine as claimed in claim 1 or 2, wherein the rotor is of a two pole configuration, the rotor having an air gap flux density of less than or equal to 20% of the peak value when the angle of rotation of the rotor is in the range 0 ° to 20 ° and 160 ° to 180 ° for each pole.
4. A rotor for an asynchronously started permanent magnet electric machine as claimed in claim 1 or 2, wherein the rotor is of a two-pole configuration, the waveform of the air gap flux density of the rotor being close to a sinusoidal waveform for each pole when the angle of rotation of the rotor is in the range 20 ° to 160 °.
5. A rotor for an asynchronously started permanent magnet electric machine as claimed in claim 1 or claim 2, wherein the rotor is a two-pole configuration rotor having a waveform of air gap flux density having at least two steps per pole, with the highest step being a flat-topped curve.
6. The rotor for an asynchronously started permanent magnet electric machine of claim 1 or 2, wherein the first layer of permanent magnets is configured in a straight line shape, a V-shape, a U-shape or an arc shape, and the second layer of permanent magnets is configured in a straight line shape, a V-shape, a U-shape or an arc shape.
7. The rotor for an asynchronously started permanent magnet electric machine of claim 6, wherein the first layer of permanent magnets is configured as a U-shaped set of three pieces of permanent magnets and the second layer of permanent magnets is also configured as a U-shaped set of three pieces of permanent magnets.
8. A rotor for an asynchronously started permanent magnet electric machine according to claim 1 or 2, the rotor being of a four-pole configuration or a multi-pole configuration with more than four poles.
9. A rotor for an asynchronously started permanent magnet electric machine according to claim 1 or 2, each pole permanent magnet having a three-layer arrangement or a multi-layer arrangement of more than three layers in the radial direction.
10. An asynchronous starting permanent magnet machine, characterized in that it comprises a rotor for an asynchronous starting permanent magnet machine according to any of claims 1 to 9.
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN112671133A (en) * | 2020-12-17 | 2021-04-16 | 珠海格力电器股份有限公司 | Rotor structure and motor |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN112671133A (en) * | 2020-12-17 | 2021-04-16 | 珠海格力电器股份有限公司 | Rotor structure and motor |
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