JP2004201406A - Magnet-saving type rotor of synchronous motor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a magnet-saving type rotor of a synchronous motor which has superior output characteristics. <P>SOLUTION: In the magnet-saving type rotor, an occupancy angle of a magnetic pole portion 5 of primary polarity which is occupied with a permanent magnet 2 is set as θ1, an occupancy angle of a magnetic pole portion 6 of secondary polarity which is occupied with a core portion 1 is set as θ2, and an occupancy angle of a vacancy portion 4 is set as θ0. At that time, an occupancy angle θ0 of a boundary region 7 between the magnetic pole portion 5 of primary polarity and the magnetic pole portion 6 of secondary polarity is made (θn-θ1-θ2). That is, the boundary region 7 is wholly occupied by the vacancy portion 4. The occupancy angle θ2 is set in a range of 0.9-1.1 of the occupancy angle θ1. As a result, average magnetic flux density, i.e. effective magnetic flux of a gap between a stator/a rotor can be increased. Hence, magnetic leakage flux flowing in a core part 8 in the conventional case can be reduced, so that torque can be increased with the amount of the reduction. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an improvement of a half magnet type rotor of a synchronous machine.
[0002]
[Prior art]
Permanent-magnet synchronous machines using permanent-magnet rotors usually use a built-in magnet motor (IPM) with a permanent magnet embedded in the rotor core because of its excellent mechanical strength, especially resistance to centrifugal force during high-speed rotation. Have been.
[0003]
FIG. 5 shows an example of a radial cross section of the IPM rotor. In FIG. 5, 1 is a soft iron rotor core, 2 is a permanent magnet, 3 is a magnet housing hole provided in the vicinity of the outer peripheral surface of the rotor core 1 and penetrated in the axial direction, and 4 is a magnet housing. It is a hole which is located on both sides in the circumferential direction of the hole 3 and penetrates in the axial direction. A magnetic pole portion 5 of the first polarity (for example, S pole) and a magnetic pole portion 6 of the second polarity are alternately formed in the radially outer peripheral surface portion of the magnet housing hole portion 3 by the permanent magnet 2 in the circumferential direction. A boundary portion 7 is formed between two permanent magnets adjacent to each other. Therefore, the two magnetic pole pitch θn is twice the sum of the occupation angle θ of the magnetic pole portions 5 and 6 and the occupation angle θ0 of the boundary portion 7. Reference numeral 8 denotes an iron core between the holes 4.
[0004]
Patent Document 1 below proposes a permanent magnet rotor in which the number of permanent magnets in this permanent magnet rotor is halved with respect to the number of magnetic poles, and the magnetic poles of each permanent magnet have the same radial direction. FIG. 6 shows a radial cross section of the rotor disclosed in this publication.
[0005]
In FIG. 6, 1 is a rotor core made of soft iron, 2 is a permanent magnet, 3 is a magnet housing hole provided near the outer peripheral surface of the rotor core 1 and penetrated in the axial direction, and 4 is a magnet housing. It is a hole which is located on both sides in the circumferential direction of the hole 3 and penetrates in the axial direction. A magnetic pole portion 5 of a first polarity (for example, S-pole) is formed by a permanent magnet 2 on a radially outer peripheral surface portion of the magnet housing hole portion 3, and any two void portions 4, 4 adjacent in the circumferential direction are formed. A magnetic pole portion 6 of a second polarity (for example, N pole) is formed by the permanent magnet 2 on the outer peripheral surface portion therebetween, and a boundary portion 7 is formed between the magnetic pole portions 5 and 6. Therefore, the two magnetic pole pitch θn is the sum of the occupation angle θ1 of the first polarity magnetic pole part 5, the occupation angle θ2 of the second polarity magnetic pole part 6, and the occupation angle θ0 of the boundary part 7. Reference numeral 8 denotes an iron core portion forming a gap between the magnet housing hole 3 and the hole 4.
[0006]
[Problems to be solved by the invention]
However, in the conventional permanent magnet rotor as shown in FIG. 5 described above, the core portion 8 between the holes 4 cannot be set to 0 in principle. It is necessary to secure the circumferential width of the rotor significantly larger than that of the low-speed type shown in FIG. 5, and as a result, the effective magnetic flux flowing from the rotor outer peripheral surface to the stator side due to the magnetic flux leaking through this portion is reduced, and the generated torque There was a problem that was reduced. Further, in the high-speed rotation type, the circumferential width of the magnet is reduced due to the increase in the circumferential width of the iron core portion 8, which also causes a decrease in effective magnetic flux and a decrease in torque.
[0007]
On the other hand, in the magnet half-reduced rotor of the above publication shown in FIG. 6, excellent centrifugal resistance is obtained due to the presence of the magnetic pole portion 6 of the second polarity constituted by the iron core portion. Since the thickness can be doubled, it is particularly advantageous in a high-speed type, and a reduction in the size and weight of a rotating electric machine can be expected by increasing the speed.
[0008]
However, in the conventional magnet half-reduced rotor shown in FIG. 6, the leakage magnetic flux flowing between the iron core portions 8 formed at the boundary between the hole portion 4 and the magnet housing hole portion 3 causes the case shown in FIG. Similarly, the effective magnetic flux is reduced and the generated torque is reduced, and the magnetic flux density of the magnetic pole portion 6 of the second polarity becomes smaller than that of the magnetic pole portion 5 of the first polarity due to magnetic flux leakage. There was a problem that occurs.
[0009]
The present invention has been made in view of the above problems, and has as its object to provide a magnet half-reduced rotor for a synchronous machine having excellent output characteristics.
[0010]
[Means for Solving the Problems]
A magnet half-reduced rotor of a synchronous machine according to the present invention includes a soft iron core and k permanent magnets embedded near an outer peripheral surface of the core, and the iron core has an angle θn (= 360). / K) k magnet accommodation holes which are individually penetrated in the axial direction at a pitch of / k) and individually accommodate the permanent magnets, and are located on both circumferential sides of each of the magnet accommodation holes without accommodating the permanent magnets. 2k holes formed in the axial direction, a magnetic pole portion of a first polarity formed by a radially outer peripheral surface portion of the magnet housing hole, and any two magnetic poles adjacent in the circumferential direction. A magnet half-reduced rotor of a synchronous machine having a magnetic pole portion of a second polarity constituted by an outer peripheral surface portion between the two holes.
The occupation angle of the magnetic pole portion of the first polarity is θ1, the occupation angle of the magnetic pole portion of the second polarity is θ2, and the occupation angle of the boundary region between the magnetic pole portion of the first polarity and the magnetic pole portion of the second polarity. Is defined as θ0 (= θn−θ1−θ2), the occupation angle θ0 is set equal to the occupation angle of the hole.
[0011]
That is, according to the present invention, as described with reference to FIG. 6, the void portion 4 is formed to fill the occupation angle θ0 of the boundary region 7 between the magnetic pole portion 5 of the first polarity and the magnetic pole portion 6 of the second polarity. In addition, the iron core portion 8 between the hole 4 and the magnet housing hole 3 is eliminated so that the hole 4 and the magnet housing hole 3 communicate with each other. Thereby, conventionally, the leakage magnetic flux flowing through the iron core portion 8 can be reduced to zero, and the torque can be improved accordingly. Further, by reducing the magnetic flux leakage, the symmetry of the magnetic flux distribution in the circumferential direction can be improved, and the torque ripple can be reduced.
[0012]
In a preferred embodiment, the ratio (θ0 / θn) of the occupation angle θ0 to the angle θn is set in a range of 0.05 to 0.125. According to the experimental results, it has been found that the average magnetic flux density of the gap between the stator and the rotor, that is, the effective magnetic flux can be improved. According to the estimation of the present inventor, if the ratio of the occupied angle of the hole portion per two magnetic pole pitches (θ0 / θn) is made larger than the above range, the occupied angles of the magnetic pole portion of the first polarity and the magnetic pole portion of the second polarity are increased. When the ratio (θ0 / θn) is made smaller than the above range, the average magnetic flux density of the stator / rotor gap, that is, the effective magnetic flux decreases. The magnetic resistance of the magnetic path is much smaller than the magnetic resistance of the magnetic path farther from the hole, and as a result, the non-uniformity of the magnetic flux distribution in the magnetic pole part of the second polarity becomes large. It is considered that the average magnetic flux density, that is, the effective magnetic flux decreases. This decrease in the effective magnetic flux is directly linked to a decrease in output.
[0013]
In a preferred embodiment, the occupation angle θ2 is set in a range of 0.9 to 1.1 of the occupation angle θ1. According to the experimental results, it has been found that the average magnetic flux density of the gap between the stator and the rotor, that is, the effective magnetic flux can be increased by doing so.
[0014]
In a preferred embodiment, the permanent magnet comprises a rare earth magnet. In this case, high output can be achieved by utilizing a large residual magnetic flux of the rare earth magnet. Since the rare earth magnet is brittle, it is preferable to make the magnet as thick as possible. However, in this magnet half-reduced rotor, the magnetic pole portion of the first polarity, the gap between the stator / rotor, the stator core, the gap between the stator / rotor, the magnetic pole portion of the second polarity, Since only one permanent magnet is used as a field magnetic flux source in a magnetic circuit flowing with a magnetic pole of one polarity, the thickness of the permanent magnet can be reduced to a normal rotor (see FIG. 5) without increasing the amount of expensive permanent magnet used. This can be doubled in comparison, which is particularly advantageous in a high-speed type rotating electric machine.
[0015]
BEST MODE FOR CARRYING OUT THE INVENTION
A preferred embodiment of the half magnet type rotor of the synchronous machine of the present invention will be specifically described with reference to FIG.
[0016]
In FIG. 1, 1 is a soft iron rotor core, 2 is a permanent magnet, 3 is a magnet receiving hole provided near the outer peripheral surface of the rotor core 1 and penetrated in the axial direction. It is a hole which is located on both sides in the circumferential direction of the hole 3 and penetrates in the axial direction.
[0017]
A magnetic pole portion 5 of a first polarity (for example, S-pole) is formed by a permanent magnet 2 on a radially outer peripheral surface portion of the magnet housing hole portion 3, and any two void portions 4, 4 adjacent in the circumferential direction are formed. A magnetic pole portion 6 of a second polarity (for example, N pole) is formed by the permanent magnet 2 on the outer peripheral surface portion therebetween, and a boundary portion 7 is formed between the magnetic pole portions 5 and 6. Therefore, the two magnetic pole pitch θn is the sum of the occupation angle θ1 of the first polarity magnetic pole part 5, the occupation angle θ2 of the second polarity magnetic pole part 6, and the occupation angle θ0 of the boundary part 7. The entire occupation angle θ0 of the boundary 7 is occupied by the hole 4. In this specification, the occupation angle θ is a rotation shaft insertion hole that is provided in the center in the radial direction of the rotor core (the core in the present invention) in the axial direction.
[0018]
In this embodiment, three permanent magnets 2 are used, and each permanent magnet 2 uses a rare earth magnet. The occupation angle θ1 of the first polarity magnetic pole portion 5 and the occupation angle θ2 of the second polarity magnetic pole portion 6 are set to be equal. The ratio (θ0 / θn) of the occupation angle θ0 to the angle θn corresponding to the two magnetic pole pitch is set to 0.065.
[0019]
As shown in FIG. 1, the occupation angle θ <b> 1 means an angle between two radially outer corners of the four corners of the plate-shaped permanent magnet 2. The core portion between the hole portion 4 and the outer peripheral surface of the rotor core portion 1 is made as thin as possible as long as the mechanical strength can be maintained.
[0020]
The half-magnet type rotor configured as described above can improve the magnetic flux density of the gap between the stator and the rotor as a rotor of the synchronous machine as compared with the related art, so that the output can be improved.
[0021]
The experimental results are shown in FIGS. The rotor shape is essentially the same as that of FIG. 1, and the outer diameter of the rotor core 1 is 50 mm and the inner diameter is 16 mm.
[0022]
FIG. 2 shows the average magnetic flux density of the gap between the stator and the rotor when θ1 = θ2 and the occupation angle θ0 of the hole 4 is variously changed. FIG. 2 shows that the ratio of the occupation angle 2θ0 to the angle θn (2θ0 / θn) is preferably set to 0.1 to 0.25.
[0023]
In FIG. 3, 2θ0 / θn is set to 0.125, and indicates the average magnetic flux density of the gap between the stator and the rotor when the ratio of θ1 to θ2 is variously changed. FIG. 3 shows that it is preferable to set this ratio in the range of 0.9 to 1.1.
[0024]
FIG. 4 shows the circumferential distribution of the magnetic flux in the gap between the stator and the rotor in the case where the holes 4 are provided (A) and the case where the holes 4 are not provided (B) in the half magnet type rotor. However, when there is a hole 4, the ratio of the occupation angle 2θ0 to the angle θn (2θ0 / θn) is set to 0.125, and θ1 = θ2. From FIG. 4, it can be seen that the change in the magnetic field at the boundary 7 when there is a hole 4 (A) is steeper than that when there is no hole 4 (B). That is, the magnet half-reduced rotor having the holes 4 has a smaller magnetic flux than the magnet half-reduced rotor having no holes 4 because the magnetic flux of the permanent magnet 2 leaking to the boundary 7 is smaller. It can be seen that the density is high.
[0025]
Further, from FIG. 4, when the holes 4 are present, the difference in magnetic flux density between the magnetic pole part 5 of the first polarity and the magnetic pole part 6 of the second polarity is small by the improvement in the magnetic flux density. Only, the symmetry of the circumferential distribution of the magnetic flux density is improved, and the torque ripple is reduced accordingly.
(Modification) It is obvious that the numbers of the magnet housing holes 3 and the permanent magnets 2 can be variously changed other than the three in the above embodiment.
[Brief description of the drawings]
FIG. 1 is a schematic cross-sectional view in the radial direction of a half magnet type rotor according to the present invention.
2 is a diagram showing an average magnetic flux density of a gap between a stator and a rotor when the ratio of the occupied angle of a hole is variously changed in the magnet half-reduced rotor of FIG. 1;
3 is a view showing an average magnetic flux density of a gap between a stator and a rotor when the ratio of the occupied angle between a magnetic pole portion of a first polarity and a magnetic pole portion of a second polarity is variously changed in the half magnet type rotor of FIG. 1; is there.
FIG. 4 is a diagram showing an average magnetic flux density of a gap between a stator and a rotor when the ratio of the occupied angle of a hole is variously changed in the magnet half-reduced rotor of FIG. 1;
FIG. 5 is a schematic cross-sectional view in the radial direction of a conventional permanent magnet rotor with a permanent magnet.
FIG. 6 is a schematic sectional view in the radial direction of a conventional half magnet type rotor.
[Explanation of symbols]
1 Rotor core (iron core)
2 Permanent magnet 3 Magnet accommodating hole 4 Void 5 Magnetic pole of first polarity 6 Magnetic pole of second polarity 7 Boundary θ0 Boundary angle θ1 Boundary angle θ1 of magnetic pole of first polarity θ2 Second polarity of magnetic pole Occupation angle of magnetic pole part θn Occupation angle of two magnet pitch

Claims (4)

Having a soft iron core portion and k permanent magnets embedded near the outer peripheral surface of the iron core portion;
The iron core is
K magnet accommodating holes that penetrate in the axial direction at a pitch of an angle θn (= 360 / k) and individually accommodate the permanent magnets;
2k holes that are axially penetrated and located on both sides in the circumferential direction of each magnet housing hole without housing the permanent magnet,
A magnetic pole portion of a first polarity configured by a radially outer peripheral surface portion of the magnet housing hole portion;
A magnetic pole portion of a second polarity configured by an outer peripheral surface portion between any two of the holes that are circumferentially adjacent to each other;
In a magnet half rotor of a synchronous machine having
The occupation angle of the magnetic pole portion of the first polarity is θ1, the occupation angle of the magnetic pole portion of the second polarity is θ2, and the occupation angle of the boundary region between the magnetic pole portion of the first polarity and the magnetic pole portion of the second polarity. Is defined as θ0 (= θn−θ1−θ2), the occupation angle θ0 is set equal to the occupation angle of the hole portion. The magnet half rotor of the synchronous machine according to claim 1,
The ratio of the occupation angle θ0 to the angle θn (θ0 / θn) is set in the range of 0.05 to 0.125. The magnet half-type synchronous machine according to claim 2,
The occupation angle θ2 is set in a range of 0.9 to 1.1 of the occupation angle θ1. The magnet half-type synchronous machine according to claim 3,
The permanent magnet is made of a rare earth magnet.

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