Permanent magnet rotary machine

Abstract

The present invention relates to a permanent magnet rotary machine comprising a rotator to be able to reduce a slot harmonic wave voltage component so that heat generation of the rotary machine can be reduced, and degradation of performance such as a power factor, efficiency, etc. can be minimized. A permanent magnet rotary machine according to an embodiment may comprise: a stator in which a plurality of slots and a plurality of poles are formed, coils being wound on the poles; and a rotator in which a plurality of permanent magnets are embedded and which is disposed while having a clearance from the stator and is rotatable, wherein at least one pair of groove parts are formed on a surface of the rotator to correspond to each single pole, the surface facing the stator with a clearance therebetween, and each of the groove parts has an asymmetric arc-shaped cross section.

Description

permanent magnet rotator

[0001] The present invention relates to a permanent magnet rotor having a rotor configured to reduce slot harmonic voltage components.

[0002] The rotor of a rotary permanent magnet rotor is classified into a surface permanent magnet type rotor and an interior permanent magnet type rotor depending on the attachment location and manufacturing method of the permanent magnet. A surface permanent magnet rotor is a structure in which the permanent magnet is attached to the surface of the rotor and is exposed, while an interior permanent magnet rotor is a structure in which the permanent magnet is embedded inside the rotor and is not visible from the outside.

[0003] For example, in a permanent magnet generator with a built-in rotor, the no-load phase voltage and line-to-line voltage can be significantly distorted by slot harmonics. These slot harmonics are determined by the number of poles (a) of the rotor and the number of slots (b) of the stator. Specifically, the number of slots per pole (c) is defined as b / a, and when c is an integer, the voltage waveform can be significantly distorted by slot harmonics of the order [(2×c)±1].

[0004] As voltage distortion increases, heat generation in the permanent magnet generator increases, degrading performance, such as power factor and efficiency. Therefore, a method is needed to reduce voltage waveform distortion caused by slot harmonics and thereby supply high-quality power.

[0005] The purpose of the present invention is to provide a permanent magnet rotor that can reduce heat generation of the rotor and minimize performance degradation such as power factor or efficiency by configuring the rotor so as to reduce slot harmonic voltage components.

[0006] A permanent magnet rotator according to one embodiment of the present invention comprises: a stator having a plurality of slots and a plurality of poles formed thereon, and coils wound around the poles; and a rotor having a plurality of permanent magnets embedded therein, and positioned with a gap between the stator and the rotor so as to be rotatable; and on an opposing surface of the rotor facing the stator with the gap between the stator and the rotor, at least one pair of grooves is formed corresponding to each single pole, and the grooves may have an asymmetrical arc-shaped cross-section.

[0007] According to an embodiment of the present invention, by forming a groove having a specific cross-sectional shape on the opposite surface of the rotor, it is possible to reduce the slot harmonic voltage component, thereby obtaining the effect of reducing heat generation of the rotor and minimizing the deterioration of performance such as power factor or efficiency.

[0008] In addition, according to an embodiment of the present invention, there is almost no decrease in the voltage fundamental wave (first component), so there is an advantage of not needing to increase the amount of permanent magnets used.

[0009] FIG. 1 is a drawing showing a part of a permanent magnet rotator according to a first embodiment of the present invention.

[0010] FIG. 2 is a diagram showing a no-load line-to-line voltage waveform of a permanent magnet rotating machine according to the first embodiment of the present invention.

[0011] FIG. 3 is a drawing showing a part of a permanent magnet rotator according to a second embodiment of the present invention.

[0012] FIG. 4 is a diagram showing a no-load line-to-line voltage waveform of a permanent magnet rotating machine according to a second embodiment of the present invention.

[0013] FIG. 5 is a drawing showing a part of a permanent magnet rotator according to a third embodiment of the present invention.

[0014] FIG. 6 is a diagram showing a no-load line-to-line voltage waveform of a permanent magnet rotating machine according to a third embodiment of the present invention.

[0015] Hereinafter, the present invention will be described in detail with reference to exemplary drawings. When designating components in each drawing, it should be noted that, where possible, identical components are given the same reference numerals, even if they appear in different drawings.

[0016] In this specification, terms such as first, second, etc. may be used to describe various components, but these components are not limited in order, size, position, or importance by terms such as first, second, etc., and are named only for the purpose of distinguishing one component from another.

[0017] FIG. 1 is a drawing showing a part of a permanent magnet rotator according to a first embodiment of the present invention.

[0018] A permanent magnet rotor according to a first embodiment of the present invention may include a stator (10), a rotor (20), and at least one pair of grooves (30).

[0019] The stator (10) includes a coil (12) wound on the stator. The stator may be formed in a form that a shaft (not shown) can pass through, and may be fixedly supported on a housing (not shown) of a rotating machine.

[0020] However, the fixing and arrangement relationship of the stator (10) is not necessarily limited to the example described above, and for example, the shaft may be fixed and the stator may be fixedly coupled to the outer surface of the shaft.

[0021] The stator (10) is provided with a plurality of stator core plates formed from electrical steel plates in a predetermined shape, and can be formed by stacking the plurality of stator core plates in the axial direction.

[0022] The stator (10) may include a rotor receiving hole (13) formed to extend axially so that a rotor (20) can be received at the center. In addition, the stator may include a plurality of slots (14) and a plurality of poles (15) formed alternately around the periphery of the rotor receiving hole.

[0023] A plurality of poles (15) can be arranged at equal intervals along the circumference of the stator (10), and a slot (14) can be formed between two adjacent poles.

[0024] A coil (12) is wound around a pole (15) in slots (14) on both sides. A stator (10) can be formed by winding a coil around each pole.

[0025] The rotor (20) includes a plurality of permanent magnets (22) inserted into the rotor. The rotor can be fixedly connected to the outer surface of the shaft with the shaft (not shown) passing through it, and can be received in the rotor receiving hole (13) of the stator (10) and rotated together with the shaft.

[0026] In this case, the shaft rotates together with the rotor (20), and the rotational force of the rotor can be transmitted to the outside or applied from the outside.

[0027] However, the arrangement of the rotor (20) is not necessarily limited to the example described above, and for example, the stator (10) may be fixedly connected to the outer surface of the shaft, and the rotor may be arranged to rotate around the stator while surrounding the stator.

[0028] The rotor (20) is provided with a plurality of rotor core plates formed from electrical steel plates in a predetermined shape, and can be formed by stacking the plurality of rotor core plates in the axial direction.

[0029] The rotor (20) may include a plurality of magnet insertion holes (24) formed around the shaft and into which permanent magnets (22) are inserted.

[0030] A plurality of magnet insertion holes (24) can be formed in the same shape and arranged at equal intervals along the circumference of the rotor (20) while being spaced apart from each other.

[0031] The permanent magnet (22) may be formed to have a cross-sectional shape corresponding to the cross-sectional shape of the magnet insertion hole (24), but is not necessarily limited thereto. Accordingly, a plurality of permanent magnets may be formed with the same shape. By inserting and arranging permanent magnets in each magnet insertion hole, a built-in rotor (20) can be formed.

[0032] There is an air gap (G) between the stator (10) and the rotor (20). In other words, the rotor can be positioned with a certain distance from the stator so that it can rotate in one direction or in the opposite direction while facing the stator.

[0033] At least one pair of grooves (30) may be arranged correspondingly to each single pole (N pole or S pole) of a permanent magnet (22) inserted into a magnet insertion hole (24) on the opposite surfaces of the rotor (20) that face the stator (10) and the gap (G). For example, in the case of a 28-pole rotor, 56 grooves may be formed on the rotor. Each groove may be formed to extend along the axial direction of the rotor on the opposite surfaces of the rotor.

[0034] For example, two grooves (30) forming a pair may be arranged symmetrically with respect to a reference line (L). Here, the reference line may be defined as an imaginary axis passing through the center of the circumferential length of a single pole and the center of the rotor (20).

[0035] In other words, the two paired grooves (30) each have the same distance from the reference line (L). In this case, each groove can be arranged to correspond to or be adjacent to both ends of the circumferential length of the magnet insertion hole (24) into which the permanent magnet (22) of the corresponding pole is inserted.

[0036] In addition, as illustrated in FIG. 1, when the number of slots (14) of the stator (10) per pole of the rotor (20) is 9, a pair of grooves (30) may be arranged to correspond to the slots located at the outermost ends on both sides among the slots. In other words, each groove may be arranged on the rotor to correspond to the first slot and the ninth slot of the stator defined along the circumferential direction.

[0037] Each groove (30) may have an asymmetrical arc-shaped cross-section. For example, the cross-sectional shape of each groove may include a first circular arc (41) and a second circular arc (42) extending from the first circular arc and having a curvature smaller than that of the first circular arc. In addition, the first circular arc may be positioned relatively close to the reference line (L), and the second circular arc may be positioned relatively far from the reference line.

[0038] Accordingly, the two grooves (30) forming a pair can be formed with cross-sectional shapes that are symmetrical with respect to the reference line (L). The inner surface of each groove has a relatively steep curve adjacent to the reference line, while it has a relatively gentle curve farther away from the reference line.

[0039] On opposite surfaces of the rotor (20), a plurality of pairs of grooves (31, 32) may be arranged for each single pole. That is, a pair of first grooves (31) and a pair of second grooves (32) may be formed corresponding to a single pole on opposite surfaces of the rotor. A pair of first grooves may be positioned relatively farther away from the reference line (L) than a pair of second grooves.

[0040] In this case, each first groove (31) can be arranged to correspond to or be adjacent to both ends of the circumferential length of the magnet insertion hole (24) into which the permanent magnet (22) of the corresponding pole is inserted.

[0041] In addition, as illustrated in FIG. 1, when the number of slots (14) of the stator (10) per pole of the rotor (20) is 9, a pair of first grooves (31) may be arranged to correspond to the slots located at the outermost ends on both sides among the slots. In other words, each first groove may be arranged on the rotor to correspond to the first slot and the ninth slot of the stator defined along the circumferential direction.

[0042] In addition, each second home portion (32) can be positioned corresponding to the middle of the circumferential length of the magnet insertion hole (24) into which the permanent magnet (22) of the corresponding pole is inserted.

[0043] For example, as shown in FIG. 1, when the number of slots (14) of the stator (10) per pole of the rotor (20) is 9, each second groove portion may be arranged in the rotor to correspond to the third slot and the seventh slot of the stator defined along the circumferential direction, but is not necessarily limited thereto.

[0044] The first groove (31) and the second groove (32) may each have an asymmetrical arc-shaped cross-section. For example, the cross-sectional shape of the first groove may include a first circular arc (41) and a second circular arc (42) extending from the first circular arc and having a curvature smaller than that of the first circular arc. Similarly, the cross-sectional shape of the second groove may include a third circular arc (43) and a fourth circular arc (44) extending from the third circular arc and having a curvature smaller than that of the third circular arc.

[0045] Additionally, the first circular arc (41) and the third circular arc (43) may be positioned relatively close to the reference line (L), and the second circular arc (42) and the fourth circular arc (44) may be positioned relatively far from the reference line.

[0046] Accordingly, the two first grooves (31) forming a pair can be formed with cross-sectional shapes that are symmetrical with respect to the reference line (L). The two second grooves (32) can also be formed with cross-sectional shapes that are symmetrical with respect to the reference line. The inner surface of each groove has a relatively steep curve adjacent to the reference line, while it has a relatively gentle curve farther away from the reference line.

[0047] The first groove (31) and the second groove (32) may have different cross-sectional sizes. For example, the first groove, which is located relatively far from the reference line (L), may be formed to have a larger cross-sectional area than the second groove.

[0048] For this purpose, the third circular arc (43) may have a curvature radius of 20-70% greater than the curvature radius of the first circular arc (41), and the fourth circular arc (44) may have a curvature radius of 20-70% greater than the curvature radius of the second circular arc (42).

[0049] In this way, in the permanent magnet rotor according to the first embodiment of the present invention, by arranging at least one pair of grooves (30) on the opposing surfaces of the stator (10) and the rotor (20) with the gap (G) facing each other, the permeance of the gap portion changes, and the zigzag reactance is reduced, thereby reducing the slot harmonic voltage component.

[0050] Specifically, the fringing effect in the rotor (20) is increased by at least one pair of grooves (30), thereby increasing the effective air gap length within the rotor. In addition, the length of the rotor surface is reduced by the grooves.

[0051] Moreover, since the cross-section of the groove part has an asymmetrical arc shape, the effective air gap length can be further increased and the length of the rotor surface can be further reduced compared to the case of a groove part having a symmetrical cross-section.

[0052] Due to their influence, the permeance of the gap portion is reduced, which in turn reduces the zigzag reactance and thus reduces harmonic components. In other words, at least one pair of grooves (30) can act as a voltage filter capable of removing specific harmonics from the permanent magnet rotator.

[0053] FIG. 2 is a diagram showing a no-load line-to-line voltage waveform of a permanent magnet rotating machine according to the first embodiment of the present invention.

[0054] In Fig. 2, the solid line represents the no-load line-to-line voltage waveform of the permanent magnet rotator according to the first embodiment of the present invention illustrated in Fig. 1, and the dotted line represents the no-load line-to-line voltage waveform of the permanent magnet rotator according to the prior art without a groove.

[0055] Here, the conventional permanent magnet rotor includes a rotor having 28 poles and a stator having 9 slots per pole. For example, when the number of slots per pole is 9, the 17th harmonic and the 19th harmonic are mainly generated.

[0056] As can be seen in Fig. 2, in the permanent magnet rotating machine according to the first embodiment of the present invention, it can be confirmed that the distortion of the no-load line voltage is visibly greatly reduced.

[0057] When analyzing the waveform by fast Fourier transform (FFT), it is shown that the distortion factor (total harmonic distortion, THD) of the no-load line voltage in the first embodiment of the present invention is significantly reduced from 5.14% in the prior art to 2.09%.

[0058] Additionally, in the first embodiment of the present invention, the 17th harmonic is shown to be reduced from 3.80% of the prior art to 0.43%, and the 19th harmonic is shown to be reduced from 3.22% of the prior art to 1.40%.

[0059] Moreover, when the fundamental wave (first component) of the counter electromotive force of the no-load line voltage in the prior art is 100 (V), the fundamental wave in the first embodiment of the present invention shows 99.56 (V), so it can be seen that the fundamental wave is maintained at the same level with almost no decrease in the fundamental wave.

[0060] Therefore, the permanent magnet rotor according to the first embodiment of the present invention has the advantage of being able to reduce the slot harmonic voltage component by forming a groove (30) on the opposite surface of the rotor (20), and the fundamental voltage can be maintained at almost the same level.

[0061] FIG. 3 is a drawing showing a part of a permanent magnet rotator according to a second embodiment of the present invention.

[0062] A rotary machine according to a second embodiment of the present invention may include a stator (10), a rotor (20), and at least one pair of grooves (30).

[0063] The second embodiment illustrated in FIG. 3 differs only in the arrangement of the grooves (30; 31, 32) in the rotor (20) and the number of slots (14) in the stator (10), and the remaining components are identical to those of the first embodiment. Accordingly, in describing the permanent magnet rotator of the second embodiment, the same reference numerals are given to the same components as those of the permanent magnet rotator of the first embodiment described above, and a detailed description of their configuration and function is omitted.

[0064] At least one pair of grooves (30) can be arranged correspondingly to each single pole (N pole or S pole) of a permanent magnet (22) inserted into a magnet insertion hole (24) on the opposite surface of the rotor (20) facing the stator (10) with the gap (G). For example, in the case of a 28-pole rotor, 56 grooves can be formed on the rotor. Each groove can be formed to extend along the axial direction of the rotor on the opposite surface of the rotor. For example, two grooves forming one pair can be arranged symmetrically with respect to a reference line (L).

[0065] In this case, each groove (30) may be arranged to correspond to or be adjacent to both ends of the circumferential length of the magnet insertion hole (24) into which the permanent magnet (22) of the corresponding pole is inserted. In addition, as illustrated in FIG. 3, when the number of slots (14) of the stator (10) per pole of the rotor (20) is 6 and the number of corresponding poles (15) is 5, a pair of grooves may be arranged to correspond to the poles located at the outermost ends on both sides among the corresponding poles. In other words, each groove may be arranged on the rotor to correspond to the first and fifth poles of the stator defined along the circumferential direction.

[0066] The two grooves (30) forming a pair can be formed with cross-sectional shapes that are symmetrical with respect to the reference line (L). The inner surface of each groove has a relatively steep curve adjacent to the reference line, while it has a relatively gentle curve when it is away from the reference line.

[0067] On opposite surfaces of the rotor (20), a plurality of pairs of grooves (31, 32) may be arranged for each single pole. That is, a pair of first grooves (31) and a pair of second grooves (32) may be formed corresponding to a single pole on opposite surfaces of the rotor. A pair of first grooves may be positioned relatively farther away from the reference line (L) than a pair of second grooves.

[0068] In this case, each first groove (31) can be arranged to correspond to or be adjacent to both ends of the circumferential length of the magnet insertion hole (24) into which the permanent magnet (22) of the corresponding pole is inserted.

[0069] In addition, as illustrated in FIG. 3, when the number of slots (14) of the stator (10) per pole of the rotor (20) is 6 and the number of corresponding poles (15) is 5, a pair of first grooves (31) may be arranged to correspond to the poles located at the outermost ends on both sides among the corresponding poles. In other words, each first groove may be arranged on the rotor to correspond to the first and fifth poles of the stator defined along the circumferential direction.

[0070] In addition, each second groove (32) may be arranged to correspond to the middle of the circumferential length of the magnet insertion hole (24) into which the permanent magnet (22) of the corresponding pole is inserted. For example, as illustrated in FIG. 3, when the number of slots (14) of the stator (10) per pole of the rotor (20) is 6 and the corresponding number of poles (15) is 5, each second groove may be arranged on the rotor to correspond to the second and fourth poles of the stator defined along the circumferential direction, but is not necessarily limited thereto.

[0071] The two first grooves (31) forming a pair may be formed with cross-sectional shapes that are symmetrical with respect to the reference line (L). The two second grooves (32) may also be formed with cross-sectional shapes that are symmetrical with respect to the reference line. The inner surface of each groove has a relatively steep curve adjacent to the reference line, while it has a relatively gentle curve farther away from the reference line.

[0072] The first groove (31) and the second groove (32) may have different cross-sectional sizes. For example, the first groove, which is located relatively far from the reference line, may be formed to have a larger cross-sectional area than the second groove.

[0073] In this way, in the permanent magnet rotor according to the second embodiment of the present invention, by arranging at least one pair of grooves (30) on the opposite surfaces of the stator (10) and the rotor (20) with the gap (G) facing each other, the permeance of the gap portion changes, the zigzag reactance is reduced, and the slot harmonic voltage component can be reduced.

[0074] At least one pair of grooves is capable of acting as a voltage filter to remove certain harmonics from the rotor.

[0075] FIG. 4 is a diagram showing a no-load line-to-line voltage waveform of a permanent magnet rotating machine according to a second embodiment of the present invention.

[0076] In Fig. 4, the solid line represents the no-load line-to-line voltage waveform of the permanent magnet rotator according to the second embodiment of the present invention illustrated in Fig. 3, and the dotted line represents the no-load line-to-line voltage waveform of the permanent magnet rotator according to the prior art without a groove.

[0077] Here, the conventional permanent magnet rotor includes a rotor having 28 poles and a stator having 6 slots per pole. For example, when the number of slots per pole is 6, the 11th harmonic and the 13th harmonic are mainly generated.

[0078] As can be seen in Fig. 4, in the permanent magnet rotating machine according to the second embodiment of the present invention, it can be confirmed that the distortion of the no-load line voltage is visibly greatly reduced.

[0079] When analyzing the waveform by fast Fourier transform (FFT), it is shown that the total harmonic distortion (THD) of the no-load line voltage in the second embodiment of the present invention is significantly reduced from 13.85% in the prior art to 2.73%.

[0080] Additionally, in the second embodiment of the present invention, the 11th harmonic is shown to be reduced from 11.17% of the prior art to 1.47%, and the 13th harmonic is shown to be reduced from 8.05% of the prior art to 1.93%.

[0081] Moreover, when the fundamental wave (first component) of the counter electromotive force of the no-load line voltage in the prior art is 100 (V), the fundamental wave in the second embodiment of the present invention shows 100.19 (V), so it can be seen that the fundamental wave is maintained at the same level.

[0082] Therefore, the permanent magnet rotor according to the second embodiment of the present invention has the advantage of being able to reduce the slot harmonic voltage component by forming a groove (30) on the opposite surface of the rotor (20), and the fundamental voltage can be maintained at the same level.

[0083] FIG. 5 is a drawing showing a part of a permanent magnet rotator according to a third embodiment of the present invention.

[0084] A rotary machine according to a third embodiment of the present invention may include a stator (10), a rotor (20), and at least one pair of grooves (30).

[0085] The third embodiment illustrated in Fig. 5 differs only in the arrangement of the grooves (30) in the rotor (20) and the number of slots (14) in the stator (10), and the remaining components are identical to those of the first embodiment. Accordingly, in describing the permanent magnet rotator of the third embodiment, the same reference numerals are given to the same components as those of the permanent magnet rotator according to the first embodiment described above, and a detailed description of their configuration and function is omitted.

[0086] At least one pair of grooves (30) can be arranged correspondingly to each single pole (N pole or S pole) of a permanent magnet (22) inserted into a magnet insertion hole (24) on the opposite surface of the rotor (20) facing the stator (10) with the gap (G). For example, in the case of a 28-pole rotor, 56 grooves can be formed on the rotor. Each groove can be formed to extend along the axial direction of the rotor on the opposite surface of the rotor. For example, two grooves forming one pair can be arranged symmetrically with respect to a reference line (L).

[0087] In this case, each groove (30) may be arranged to correspond to or be adjacent to both ends of the circumferential length of the magnet insertion hole (24) into which the permanent magnet (22) of the corresponding pole is inserted. In addition, as illustrated in FIG. 5, when the number of slots (14) of the stator (10) per pole of the rotor (20) is 12, a pair of grooves may be arranged to correspond to the slots located at the outermost ends on both sides among the slots. In other words, each groove may be arranged on the rotor to correspond to the first slot and the twelfth slot of the stator defined along the circumferential direction.

[0088] The two grooves (30) forming a pair can be formed with cross-sectional shapes that are symmetrical with respect to the reference line (L). The inner surface of each groove has a relatively steep curve adjacent to the reference line, while it has a relatively gentle curve when it is away from the reference line.

[0089] On opposite surfaces of the rotor (20), a plurality of pairs of grooves (31, 32) may be arranged for each single pole. That is, a pair of first grooves (31) and a pair of second grooves (32) may be formed corresponding to a single pole on opposite surfaces of the rotor. A pair of first grooves may be positioned relatively farther away from the reference line (L) than a pair of second grooves.

[0090] In this case, each first groove (31) can be arranged to correspond to or be adjacent to both ends of the circumferential length of the magnet insertion hole (24) into which the permanent magnet (22) of the corresponding pole is inserted.

[0091] In addition, as illustrated in FIG. 5, when the number of slots (14) of the stator (10) per pole of the rotor (20) is 12, a pair of first grooves (31) may be arranged to correspond to the slots located at the outermost ends on both sides among the slots. In other words, each first groove may be arranged on the rotor to correspond to the first slot and the twelfth slot of the stator defined along the circumferential direction.

[0092] In addition, each second groove (32) may be arranged to correspond to the middle of the circumferential length of the magnet insertion hole (24) into which the permanent magnet (22) of the corresponding pole is inserted. For example, as illustrated in FIG. 5, when the number of slots (14) of the stator (10) per pole of the rotor (20) is 12, each second groove may be arranged on the rotor to correspond to the second slot and the eleventh slot of the stator defined along the circumferential direction, but is not necessarily limited thereto.

[0093] The two first grooves (31) forming a pair may be formed with cross-sectional shapes that are symmetrical with respect to the reference line (L). The two second grooves (32) may also be formed with cross-sectional shapes that are symmetrical with respect to the reference line. The inner surface of each groove has a relatively steep curve adjacent to the reference line, while it has a relatively gentle curve farther away from the reference line.

[0094] The first groove (31) and the second groove (32) may have different cross-sectional sizes. For example, the first groove, which is located relatively far from the reference line (L), may be formed to have a larger cross-sectional area than the second groove.

[0095] In this way, in the permanent magnet rotor according to the third embodiment of the present invention, by arranging at least one pair of grooves (30) on the opposing surfaces of the stator (10) and the rotor (20) with the gap (G) facing each other, the permeance of the gap portion changes, the zigzag reactance is reduced, and the slot harmonic voltage component can be reduced.

[0096] At least one pair of grooves (30) can serve as a voltage filter capable of removing specific harmonics from the rotor.

[0097] FIG. 6 is a diagram showing a no-load line-to-line voltage waveform of a permanent magnet rotating machine according to a third embodiment of the present invention.

[0098] In Fig. 6, the solid line represents the no-load line-to-line voltage waveform of the permanent magnet rotator according to the third embodiment of the present invention illustrated in Fig. 5, and the dotted line represents the no-load line-to-line voltage waveform of the permanent magnet rotator according to the prior art without a groove.

[0099] Here, the conventional permanent magnet rotor includes a rotor having 28 poles and a stator having 12 slots per pole. For example, when the number of slots per pole is 12, the 23rd harmonic and the 25th harmonic are mainly generated.

[0100] As can be seen in Fig. 6, in the permanent magnet rotating machine according to the third embodiment of the present invention, it can be confirmed that the distortion of the no-load line voltage is visibly reduced.

[0101] When analyzing the waveform by fast Fourier transform (FFT), it is shown that the total harmonic distortion (THD) of the no-load line voltage in the third embodiment of the present invention is reduced from 3.27% in the prior art to 2.05%.

[0102] Additionally, in the third embodiment of the present invention, the 23rd harmonic is shown to be reduced from 1.91% of the prior art to 0.45%, and the 25th harmonic is shown to be reduced from 2.36% of the prior art to 0.88%.

[0103] Moreover, when the fundamental wave (first component) of the counter electromotive force of the no-load line voltage in the prior art is 100 (V), the fundamental wave in the third embodiment of the present invention shows 100.87 (V), so it can be seen that the fundamental wave is maintained at the same level or is slightly increased.

[0104] Therefore, the permanent magnet rotor according to the third embodiment of the present invention has the advantage of being able to reduce slot harmonic voltage components by forming a groove on the opposite surface of the rotor, and maintaining the fundamental voltage at the same level.

[0105] As described above, according to an embodiment of the present invention, by forming a groove having a specific cross-sectional shape on the opposite surface of the rotor, it is possible to reduce the slot harmonic voltage component, thereby reducing the heat generation of the rotor and minimizing the deterioration of performance such as power factor or efficiency.

[0106] The above description is merely an example of the technical idea of ​​the present invention, and those skilled in the art will appreciate that various modifications and variations can be made without departing from the essential characteristics of the present invention.

[0107] For example, the above-described and illustrated embodiments of the present invention may be combined with each other, and each embodiment may optionally further employ or replace some components of other embodiments as needed.

[0108] Accordingly, the embodiments disclosed in this specification and drawings are intended to illustrate, rather than limit, the technical concepts of the present invention, and the scope of the technical concepts of the present invention is not limited by these embodiments. The scope of protection of the present invention should be interpreted by the following claims, and all technical concepts within the scope equivalent thereto should be construed as being included within the scope of the present invention.

[0109] The present invention is useful for providing a permanent magnet generator capable of supplying high-quality electric power by reducing distortion of a voltage waveform.

Claims

1. A stator having a plurality of slots and a plurality of poles alternately formed and having coils wound on the poles; and A rotor in which multiple permanent magnets are embedded and arranged with a gap between the stator and the rotor so as to be rotatable. Including, At least one pair of grooves is formed corresponding to each single pole on the opposite surface of the rotor that faces the stator with a gap therebetween, The above home part is a permanent magnet rotator having an asymmetrical arc-shaped cross-section.

2. In paragraph 1, The two above-mentioned grooves forming a pair are arranged symmetrically with cross-sectional shapes symmetrical with respect to the reference line, A permanent magnet rotor, wherein the above reference line is defined as an imaginary axis passing through the center of the circumferential length of the single pole and the center of the rotor.

3. In paragraph 2, The above home portion is a permanent magnet rotator arranged to correspond to at least one end of the circumferential length of the magnet insertion hole into which the permanent magnet is inserted.

4. In paragraph 3, The above home portion is a permanent magnet rotating machine arranged on the rotor so as to correspond to the slot located at the outermost position along the circumference among the slots corresponding to the corresponding pole.

5. In paragraph 3, The above home portion is a permanent magnet rotating machine arranged on the rotor so as to correspond to the pole located at the outermost end along the circumference among the poles corresponding to the corresponding pole.

6. In paragraph 2, A permanent magnet rotator having a cross-sectional shape of the above-mentioned home portion, comprising a first circular arc and a second circular arc extending from the first circular arc and having a curvature smaller than that of the first circular arc.

7. In paragraph 6, The above first circular arc is a permanent magnet rotating machine positioned relatively closer to the reference line than the above second circular arc.

8. In paragraph 2, The above home portion includes a pair of first home portions and a pair of second home portions, A permanent magnet rotator in which the first groove is located relatively farther away from the reference line than the second groove.

9. In paragraph 8, The above first groove is arranged to correspond to the end of the circumferential length of the magnet insertion hole into which the permanent magnet is inserted, The second groove is a permanent magnet rotator arranged to correspond to the middle of the circumferential length of the magnet insertion hole.

10. In paragraph 9. The above first home portion is a permanent magnet rotating machine arranged on the rotor so as to correspond to the slot located at the outermost position along the circumference among the slots corresponding to the corresponding pole.

11. In paragraph 9, The above first home portion is a permanent magnet rotating machine arranged on the rotor so as to correspond to the pole located at the outermost end along the circumference among the poles corresponding to the corresponding pole.

12. In paragraph 8, The first groove and the second groove each have an asymmetrical arc-shaped cross-section, The cross-sectional shape of the first groove includes a first circular arc and a second circular arc extending from the first circular arc and having a curvature smaller than that of the first circular arc. A permanent magnet rotator having a cross-sectional shape of the second groove, including a third circular arc and a fourth circular arc extending from the third circular arc and having a curvature smaller than that of the third circular arc.

13. In paragraph 12, The above first arc is positioned relatively closer to the reference line than the above second arc, The third circular arc is a permanent magnet rotating machine positioned relatively closer to the reference line than the fourth circular arc.

14. In paragraph 12, A permanent magnet rotator in which the first groove and the second groove have different cross-sectional sizes.

15. In paragraph 14, A permanent magnet rotator in which the first groove portion is formed with a larger cross-sectional area than the second groove portion.

16. In paragraph 14, A permanent magnet rotator wherein the third arc has a curvature radius that is 20-70% greater than the curvature radius of the first arc, and the fourth arc has a curvature radius that is 20-70% greater than the curvature radius of the second arc.

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