Rotor, motor, compressor and refrigerator
The rotor design with separate slots for permanent magnets and soft magnetic plates addresses thermal demagnetization issues by minimizing heat transfer and enhancing magnetic flux, ensuring stable motor operation.
Patent Information
- Application Number
- JP2024025357
- Authority / Receiving Office
- JP · JP
- Patent Type
- Applications
- Current Assignee / Owner
- Filing Date
- 2024-02-22
- Publication Date
- 2025-09-03
AI Technical Summary
In motors with soft magnetic plates, abnormal changes in the magnetic field can generate eddy currents leading to thermal demagnetization of permanent magnets due to heat conduction from the soft magnetic plates.
The rotor design includes separate slots for permanent magnets and soft magnetic plates, with the soft magnetic plates positioned away from the permanent magnets to minimize heat transfer and features that enhance magnetic flux passage, such as radial placement and specific dimensions to manage eddy current losses.
This configuration suppresses thermal demagnetization of permanent magnets, maintains torque performance, and improves rotor design flexibility by managing eddy current losses effectively.
Smart Images
Figure 2025128603000001_ABST
Abstract
Description
[Technical Field]
[0001] The present disclosure relates to a rotor, a motor, a compressor, and a refrigeration device. [Background technology]
[0002] Motors equipped with soft magnetic plates are known (for example, Patent Document 1). In the technology described in Patent Document 1, the soft magnetic plates are housed in slots into which permanent magnets are inserted. According to this technology, the soft magnetic plates suppress thermal demagnetization of the permanent magnets. [Prior art documents] [Patent documents]
[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2016-5356 Summary of the Invention [Problem to be solved by the invention]
[0004] When a motor experiences abnormal operation, such as loss of synchronism, abnormal changes in the magnetic field may occur in the rotor. In this case, in a rotor having a soft magnetic plate, the abnormal changes in the magnetic field may generate eddy currents in the soft magnetic plate, which may cause the soft magnetic plate to heat up. When the soft magnetic plate heats up, heat conduction from the soft magnetic plate to the permanent magnet may cause thermal demagnetization in the permanent magnet. It is desirable to be able to suppress the effects of abnormal changes in the magnetic field on the permanent magnet. [Means for solving the problem]
[0005] A rotor of a first aspect that solves this problem is a rotor of a motor that rotates around a rotation axis by a magnetic field generated by a stator of the motor, and includes a rotor core, permanent magnets that are arranged in the rotor core and through which the magnetic flux of the magnetic field passes, and a soft magnetic plate that is arranged in the rotor core and through which the magnetic flux that passes through the permanent magnets passes, wherein when the magnetic field changes, the eddy current loss per unit volume that occurs in the soft magnetic plate is greater than the eddy current loss per unit volume that occurs in the rotor core, and the rotor core is provided with a first slot that houses the permanent magnet and a second slot that houses the soft magnetic plate at a position away from the first slot.
[0006] With this configuration, the soft magnetic plate is inserted into a slot separate from the permanent magnet, so even if the soft magnetic plate heats up due to eddy currents generated by abnormal changes in the magnetic field, the heat is less likely to be transferred from the soft magnetic plate to the permanent magnet. Because heat transfer from the soft magnetic plate to the permanent magnet is suppressed, the impact of abnormal changes in the magnetic field on the permanent magnet can be suppressed.
[0007] A rotor according to a second aspect is the rotor according to the first aspect, wherein the soft magnetic plate is disposed radially outward of the permanent magnet with respect to the rotation axis.
[0008] The magnetic flux of the magnetic field is formed from the teeth of the stator around which the windings are wound to the rotor. With this configuration, the soft magnetic plate is positioned closer to the teeth than the permanent magnet, so the magnetic flux of the magnetic field passing through the soft magnetic plate can be increased.
[0009] A rotor of a third aspect is the rotor of the first or second aspect, wherein in a plane perpendicular to the rotation axis, the length of the surface of the soft magnetic plate extending in the longitudinal direction is shorter than the length of the surface of the permanent magnet extending in the longitudinal direction.
[0010] With this configuration, in a plane perpendicular to the rotation axis, the length of the longitudinal surface of the soft magnetic plate is shorter than the length of the longitudinal surface of the permanent magnet. This allows the soft magnetic plate to be smaller than the permanent magnet. By making the soft magnetic plate smaller, it is easier to arrange the soft magnetic plate on the rotor core, improving the degree of freedom in rotor design.
[0011] A rotor of a fourth aspect is a rotor of any one of the first to third aspects, wherein the soft magnetic plate has a first soft magnetic plate through which the magnetic flux passing through a first end of the permanent magnet passes, and a second soft magnetic plate through which the magnetic flux passing through a second end of the permanent magnet opposite the first end passes, and the first soft magnetic plate and the second soft magnetic plate are arranged at a distance from each other in the circumferential direction of the rotation axis.
[0012] According to this configuration, the first soft magnetic plate, through which the magnetic flux passing through the first end of the permanent magnet passes, and the second soft magnetic plate, through which the magnetic flux passing through the second end of the permanent magnet passes, are spaced apart in the circumferential direction. Therefore, the magnetic flux passing between the first soft magnetic plate and the second soft magnetic plate is less affected by the first soft magnetic plate and the second soft magnetic plate. The torque performance of the rotor can be maintained by the magnetic flux of the magnetic field that rotates the rotor passing between the first soft magnetic plate and the second soft magnetic plate.
[0013] A rotor according to a fifth aspect is the rotor according to any one of the first to fourth aspects, wherein the soft magnetic plate is arranged radially inward of the permanent magnet with respect to the rotation axis.
[0014] According to this configuration, the number of magnetic fluxes passing through the soft magnetic plate in the magnetic field for rotating the rotor can be reduced, thereby suppressing a decrease in the torque performance of the motor including the rotor.
[0015] A rotor of a sixth aspect is a rotor of any one of the first to fifth aspects, wherein the soft magnetic plate is arranged so that a surface of the soft magnetic plate extending in the longitudinal direction intersects with the magnetic flux in a plane perpendicular to the rotation axis.
[0016] According to this configuration, the magnetic flux of the magnetic field passes through the surface extending in the longitudinal direction of the soft magnetic plate, and therefore the magnetic flux of the magnetic field passing through the soft magnetic plate can be increased.
[0017] A rotor according to a seventh aspect is the rotor according to any one of the first to sixth aspects, wherein the thickness of the soft magnetic plate is 0.2 mm or more and 0.5 mm or less.
[0018] According to this configuration, the thickness of the soft magnetic plate is 0.2 mm or more, which makes it easy to handle the soft magnetic plate. Also, the thickness of the soft magnetic plate is 0.5 mm or less, which improves the degree of freedom in arranging the soft magnetic plate.
[0019] A motor according to an eighth aspect includes the rotor according to any one of the first to seventh aspects, and the stator that generates the magnetic field that rotates the rotor around the rotation axis.
[0020] With this configuration, even if an abnormal change in the magnetic field occurs in the motor, the motor is less susceptible to the influence of the abnormal change in the magnetic field, and therefore a decrease in the torque performance of the motor can be suppressed.
[0021] A compressor according to a ninth aspect includes the motor according to the eighth aspect.
[0022] According to this configuration, the deterioration of the torque performance of the motor is suppressed, and the compressor can operate stably.
[0023] A refrigeration device according to a tenth aspect includes the compressor according to the ninth aspect.
[0024] According to this configuration, the compressor can operate stably, and the operation of the refrigeration system can be continued in a favorable manner. [Brief explanation of the drawings]
[0025] [Figure 1] 1 is a schematic configuration diagram of a refrigeration device according to an embodiment. [Figure 2] 1 is a cross-sectional view of a compressor according to an embodiment. [Figure 3]FIG. 2 is a plan view of the motor according to the embodiment. [Figure 4] 1 is a cross-sectional view of a motor according to an embodiment. [Figure 5] FIG. 2 is a schematic diagram of a rotor according to an embodiment. [Figure 6] FIG. 2 is a schematic diagram showing an example of magnetic flux of a magnetic field generated in a motor. [Figure 7] FIG. 2 is a schematic diagram showing an example of magnetic flux of a magnetic field generated in a motor. [Figure 8] FIG. 2 is a schematic diagram showing an example of magnetic flux of a magnetic field generated in a motor. [Figure 9] FIG. 1 is a schematic diagram showing a motor model in a method for evaluating demagnetization resistance. [Figure 10] FIG. 1 is a circuit diagram of a motor and a power supply in a method for evaluating demagnetization resistance. [Figure 11] 10 is a graph showing the waveform of a current passed through a motor in a method for evaluating demagnetization resistance. [Figure 12] 10 is a graph showing a waveform of a voltage of a motor in a method for evaluating demagnetization resistance. [Figure 13] 1 is a graph showing a demagnetization rate versus a demagnetization current in a method for evaluating demagnetization resistance. [Figure 14] 1 is a graph showing current, magnetic flux, and eddy current loss per unit volume in an evaluation method of eddy current loss. [Figure 15] FIG. 10 is a schematic diagram of a rotor according to a modified example. [Figure 16] FIG. 10 is a schematic diagram of a rotor according to a modified example. [Figure 17] FIG. 10 is a schematic diagram of a rotor according to a modified example. [Figure 18] FIG. 10 is a schematic diagram of a rotor according to a modified example. DETAILED DESCRIPTION OF THE INVENTION
[0026] <Embodiment> A refrigeration device 1, a compressor 10, a motor 100, and a rotor 300 according to an embodiment will be described with reference to FIGS.
[0027] <Refrigeration equipment> 1 and 2, the refrigeration device 1 includes a refrigerant circuit R. The refrigerant circuit R is filled with a refrigerant. The refrigerant circuit R performs a vapor compression refrigeration cycle. The refrigeration device 1 includes a compressor 10. The compressor 10 is provided in the refrigerant circuit R of the refrigeration device 1.
[0028] 2 shows a cross-sectional view of the compressor 10 taken along the rotation axis AC of the motor 100. In one example, the compressor 10 is a rotary compressor. The compressor 10 is a swing piston compressor. The compressor 10 may also be a scroll, screw, or turbo compressor.
[0029] The compressor 10 includes a motor 100. The compressor 10 further includes a drive shaft 11 and a compression mechanism 12. The motor 100 is housed in a casing 13. In one example, the casing 13 is made of a metal material and has a cylindrical shape.
[0030] The drive shaft 11 is provided in the casing 13 so as to extend along the rotation axis AC. The drive shaft 11 is driven to rotate around the rotation axis AC. One end of the drive shaft 11 is rotatably supported by a bearing 14. The other end of the drive shaft 11 is fixed to the rotor 300 of the motor 100.
[0031] The compression mechanism 12 is housed in a casing 13. The compression mechanism 12 has a cylinder 15 and a piston 16. The piston 16 is connected to the drive shaft 11 and is provided inside the cylinder 15. A cylinder chamber 17 is formed between the inner periphery of the cylinder 15 and the outer periphery of the piston 16.
[0032] The compression mechanism 12 has a suction pipe 18 and a discharge pipe 19. The suction pipe 18 communicates with a cylinder chamber 17 of the compression mechanism 12. The discharge pipe 19 communicates with the internal space of the casing 13.
[0033] In one example, in addition to the compressor 10, the refrigerant circuit R is provided with a radiator 20, a pressure reduction mechanism 30 constituted by an expansion valve, and an evaporator 40. In the refrigeration cycle, the refrigerant is compressed by the compressor 10 and then dissipates heat into the air in the radiator 20. The refrigerant that has dissipated heat is reduced in pressure by the pressure reduction mechanism 30 and then evaporated in the evaporator 40. The evaporated refrigerant is drawn into the compressor 10.
[0034] Low-pressure refrigerant from the refrigerant circuit R is drawn into a cylinder chamber 17 of the compression mechanism 12 via a suction pipe 18. The compression mechanism 12 compresses the refrigerant in the cylinder chamber 17 with a piston 16 driven by a drive shaft 11. The interior of the casing 13 is filled with high-pressure refrigerant discharged from the compression mechanism 12. This high-pressure refrigerant flows through the motor 100 and is then discharged into the refrigerant circuit R via a discharge pipe 19.
[0035] <Motor> FIG. 3 shows a plan view of motor 100 taken along a plane perpendicular to rotation axis AC of motor 100. FIG. 4 shows a cross-sectional view of motor 100 taken along rotation axis AC of motor 100. Motor 100 is an embedded magnet motor. In one example, motor 100 is an inner rotor motor. Motor 100 includes a stator 200 and a rotor 300.
[0036] The stator 200 is provided radially outside the rotor 300 at a distance so as to face the rotor 300 in the radial direction. The stator 200 generates a magnetic field that rotates the rotor 300 about the rotation axis AC. The stator 200 has a stator core 210 and a winding 220.
[0037] The stator core 210 is configured by stacking a plurality of annular stator plates 211 in the axial direction. In one example, the stator plates 211 are formed from pressed electromagnetic steel sheets. Adjacent stator plates 211 are fixed to each other by, for example, caulking. The stator plates 211 are stacked while being insulated from each other. In one example, the thickness of the stator plates 211 is 0.2 mm or more and 0.5 mm or less.
[0038] Stator core 210 has a back yoke 212 that forms an annular portion on the outer periphery, and a plurality of teeth 213. The plurality of teeth 213 are provided so as to extend radially inward from back yoke 212. A winding 220 is wound around each tooth 213. Winding 220 is electrically connected to a power source (not shown).
[0039] <Rotor> The rotor 300 rotates around a rotation axis AC due to the magnetic field generated by the stator 200. The rotor 300 includes a rotor core 310, a permanent magnet 320, and a soft magnetic plate 330.
[0040] <Rotor core> The rotor core 310 is configured by stacking a plurality of rotor plates 311 in the axial direction. In one example, the rotor plates 311 are formed from pressed electromagnetic steel sheets. Adjacent rotor plates 311 are fixed to each other by, for example, caulking. The rotor plates 311 are stacked while being insulated from each other. In one example, the thickness of the rotor plates 311 is 0.2 mm or more and 0.5 mm or less.
[0041] A hole is provided in the center of each rotor plate 311. In the rotor core 310, these central holes are continuous in the axial direction to form a bearing hole 312 for receiving the drive shaft 11.
[0042] The rotor core 310 is provided with first slots 313 and second slots 314. The first slots 313 and the second slots 314 are configured to extend in the axial direction by holes provided in each rotor plate 311 continuing in the axial direction. A permanent magnet 320 is housed in the first slot 313. A soft magnetic plate 330 is not housed in the first slot 313. A soft magnetic plate 330 is housed in the second slot 314 at a position separated from the first slot 313. A permanent magnet 320 is not housed in the second slot 314.
[0043] <Permanent magnet> The permanent magnet 320 is, for example, a rare earth magnet, an alnico magnet, a ferrite magnet, a bonded magnet, or the like. The permanent magnet 320 is disposed in the rotor core 310. The rotor 300 rotates around the rotation axis AC by the permanent magnet 320 being attracted by the movement of a magnetic field generated by energizing the windings 220 wound around the teeth 213 of the stator 200. In one example, the thickness of the permanent magnet 320 is 1.5 mm or more and 3 mm or less.
[0044] Referring to FIG. 5 , in one example, the permanent magnet 320 and the soft magnetic plate 330 are configured to form a rectangle in a plane perpendicular to the rotation axis AC. The rectangle of the permanent magnet 320 and the soft magnetic plate 330 has long sides extending in the longitudinal direction and short sides extending in the lateral direction. Note that, in the plane perpendicular to the rotation axis AC, the short sides extending in the lateral direction of the permanent magnet 320 correspond to the thickness of the permanent magnet 320. In the plane perpendicular to the rotation axis AC, the short sides extending in the lateral direction of the soft magnetic plate 330 correspond to the thickness of the soft magnetic plate 330. The permanent magnet 320 has a first end 321 and a second end 322. The first end 321 is the end of the surface of the permanent magnet 320 extending in the longitudinal direction in the plane perpendicular to the rotation axis AC. The second end 322 is the end of the permanent magnet 320 opposite to the first end 321.
[0045] <Soft magnetic plate> See FIG. 5. In one example, the soft magnetic plate 330 is formed from a pressed electromagnetic steel plate. The soft magnetic plate 330 is disposed in the rotor core 310. The thickness of the soft magnetic plate 330 is 0.2 mm or more and 0.5 mm or less. Preferably, the thickness of the soft magnetic plate 330 is smaller than the thickness of the permanent magnet 320. Preferably, the soft magnetic plate 330 has the same thickness and is made of the same material as the rotor plate 311. Since the soft magnetic plate 330 has the same thickness and is made of the same material as the rotor plate 311, the electromagnetic steel plate of the rotor plate 311 can be used as the soft magnetic plate 330.
[0046] In one example, the soft magnetic plate 330 includes a first soft magnetic plate 331 and a second soft magnetic plate 332. The first soft magnetic plate 331 and the second soft magnetic plate 332 are spaced apart in the circumferential direction of the rotation axis AC. With respect to the rotation axis AC, the first soft magnetic plate 331 is located radially outward from the first end 321 of the permanent magnet 320. With respect to the rotation axis AC, the second soft magnetic plate 332 is located radially outward from the second end 322 of the permanent magnet 320.
[0047] With respect to the rotation axis AC, the soft magnetic plate 330 is disposed radially outside the permanent magnet 320. In this embodiment, the first soft magnetic plate 331 and the second soft magnetic plate 332 are disposed radially outside the permanent magnet 320. The first soft magnetic plate 331 and the second soft magnetic plate 332 are disposed between the outer circumferential surface 301 of the rotor 300 and the permanent magnet 320.
[0048] In a plane perpendicular to the rotation axis AC, the length of the surface of the soft magnetic plate 330 extending in the longitudinal direction is shorter than the length of the surface of the permanent magnet 320 extending in the longitudinal direction. In a plane perpendicular to the rotation axis AC, the surface of the soft magnetic plate 330 extending in the longitudinal direction is either the surface of the soft magnetic plate 330 facing radially outward or the surface of the soft magnetic plate 330 facing radially inward. In a plane perpendicular to the rotation axis AC, the surface of the permanent magnet 320 extending in the longitudinal direction is either the surface of the permanent magnet 320 facing radially outward or the surface of the permanent magnet 320 facing radially inward.
[0049] In this embodiment, in a plane perpendicular to the rotation axis AC, the length of the surface of the first soft magnetic plate 331 extending in the longitudinal direction is shorter than the length of the surface of the permanent magnet 320 extending in the longitudinal direction. In addition, in a plane perpendicular to the rotation axis AC, the length of the surface of the second soft magnetic plate 332 extending in the longitudinal direction is shorter than the length of the surface of the permanent magnet 320 extending in the longitudinal direction. Note that the length of the surface extending in the longitudinal direction in the plane perpendicular to the rotation axis AC corresponds to the length of the long side extending in the longitudinal direction in the plane perpendicular to the rotation axis AC.
[0050] In one example, the soft magnetic plate 330 includes a third soft magnetic plate 333. The third soft magnetic plate 333 is spaced apart from the first soft magnetic plate 331 and the second soft magnetic plate 332 in the radial direction of the rotation axis AC.
[0051] With respect to the rotation axis AC, the soft magnetic plate 330 is disposed radially inside the permanent magnet 320. In this embodiment, the third soft magnetic plate 333 is disposed radially inside the permanent magnet 320. The third soft magnetic plate 333 is disposed between the inner circumferential surface 302 of the rotor 300 and the permanent magnet 320.
[0052] In a plane perpendicular to the rotation axis AC, the length of the surface of the third soft magnetic plate 333 extending in the longitudinal direction is greater than the length of the surface of the permanent magnet 320 extending in the longitudinal direction. In a plane perpendicular to the rotation axis AC, the total length of the surface of the soft magnetic plate 330 extending in the longitudinal direction is greater than the length of the surface of the permanent magnet 320 extending in the longitudinal direction.
[0053] In one example, one first soft magnetic plate 331, one second soft magnetic plate 332, and one third soft magnetic plate 333 are arranged for one permanent magnet 320. In the example of Fig. 3, four sets of patterns each including one permanent magnet 320, one first soft magnetic plate 331, one second soft magnetic plate 332, and one third soft magnetic plate 333 are arranged on the rotor core 310.
[0054] Please refer to Figures 6 to 8. Figures 6 to 8 show examples of magnetic fields generated in motor 100. Figure 6 shows a first example of the magnetic flux MF of the magnetic field at which the torque of motor 100 is maximized during maximum torque / current control. Figure 7 shows a second example of the magnetic flux MF of the magnetic field at which the output of motor 100 is maximized during maximum output control. Figure 8 shows a third example of the magnetic flux MF of the magnetic field at which motor 100 is likely to demagnetize. When the magnetic field shown in Figure 8 is generated, there is a risk that abnormal operation such as loss of synchronism may be occurring in motor 100. As an example, during abnormal operation of motor 100, the magnetic field changes from the magnetic field of the first or second example to the magnetic field of the third example.
[0055] The magnetic flux MF of the magnetic field passes through the permanent magnet 320. The permanent magnet 320 is arranged so that a surface of the permanent magnet 320 extending in the longitudinal direction intersects with the magnetic flux MF of the magnetic field in a plane perpendicular to the rotation axis AC. The magnetic flux MF passing through the permanent magnet 320 passes through the soft magnetic plate 330. In the rotor 300, the closer the soft magnetic plate 330 is to the stator 200, the more the magnetic flux MF passing through the soft magnetic plate 330 increases.
[0056] The soft magnetic plate 330 is arranged such that the longitudinally extending surface of the soft magnetic plate 330 intersects with the magnetic flux MF of the magnetic field in a plane perpendicular to the rotation axis AC. The soft magnetic plate 330 is arranged such that the radially outward facing surface of the longitudinally extending surface intersects with the magnetic flux MF of the magnetic field in a plane perpendicular to the rotation axis AC. The soft magnetic plate 330 is also arranged such that the radially inward facing surface of the longitudinally extending surface intersects with the magnetic flux MF of the magnetic field in a plane perpendicular to the rotation axis AC.
[0057] The first soft magnetic plate 331 is passed by the magnetic flux MF of the magnetic field passing through the first end 321 of the permanent magnet 320. In one example, the first soft magnetic plate 331 is passed by the magnetic flux MF between the outer circumferential surface 301 of the rotor 300 and the permanent magnet 320. The second soft magnetic plate 332 is passed by the magnetic flux MF of the magnetic field passing through the second end 322 of the permanent magnet 320. In one example, the second soft magnetic plate 332 is passed by the magnetic flux MF between the outer circumferential surface 301 of the rotor 300 and the permanent magnet 320.
[0058] 4, a change in the magnetic field generates eddy currents in the soft magnetic plate 330, resulting in eddy current loss in the soft magnetic plate 330. Furthermore, a change in the magnetic field also generates eddy currents in the rotor core 310, which may also result in eddy current loss in the rotor core 310.
[0059] When the magnetic field changes, the eddy current loss per unit volume generated in the soft magnetic plate 330 is greater than the eddy current loss per unit volume generated in the rotor core 310. The eddy current loss per unit volume generated in the rotor core 310 is calculated by dividing the sum of the eddy current losses generated in each rotor plate 311 by the volume of the rotor core 310. When eddy current loss occurs in a magnetic body through which the magnetic flux of the magnetic field passes, the eddy current loss per unit volume can be calculated using the frequency, the magnetic flux density of the magnetic flux, the dimensions of the magnetic body, and the like. For example, the eddy current loss per unit volume in the rotor plate 311 through which the magnetic flux MF of the magnetic field passes and the eddy current loss per unit volume in the soft magnetic plate 330 through which the magnetic flux MF of the magnetic field passes can be compared in magnitude using values calculated based on the dimensions in the direction along the rotation axis AC. The dimension D1 of the rotor plate 311 in the direction along the rotation axis AC is the thickness of the rotor plate 311. Specifically, the eddy current loss per unit volume in the rotor plate 311 increases in proportion to the square of the dimension D1 of the rotor plate 311. In the direction along the rotation axis AC, the dimension D2 of the soft magnetic plate 330 is larger than the dimension D1 of the rotor plate 311. The dimension D2 of the soft magnetic plate 330 is the length of the soft magnetic plate 330 in the direction along the rotation axis AC. The eddy current loss per unit volume in the soft magnetic plate 330 also increases in proportion to the square of the dimension D2 of the soft magnetic plate 330. Because the dimension D2 of the soft magnetic plate 330 is larger than the dimension D1 of the rotor plate 311, when eddy current loss occurs due to the same magnetic flux MF, the eddy current loss per unit volume generated in the soft magnetic plate 330 is larger than the eddy current loss per unit volume generated in the rotor plate 311. Because the dimension D2 of the soft magnetic plate 330 is larger than the dimension D1 of one rotor plate 311, the eddy current loss per unit volume generated in the soft magnetic plate 330 is larger than the eddy current loss per unit volume of the rotor core 310, which is obtained by dividing the total eddy current loss generated in each rotor plate 311 by the volume of the rotor core 310. In the example of Fig. 4, the dimension D1 of the rotor plate 311 is equal to the dimension of the stator plate 211 in the direction along the rotation axis AC.
[0060] <effect> The first function of this embodiment will be described. During abnormal operation of motor 100, the magnetic field of motor 100 may change. At this time, there is a risk of generating magnetic flux MF with an abnormally high magnetic flux density. When magnetic flux MF with an abnormally high magnetic flux density is generated during abnormal operation of motor 100, eddy currents are generated in soft magnetic plate 330, and these eddy currents generate an inverse magnetic field that flows in the opposite direction to the magnetic flux MF with an abnormally high magnetic flux density. The inverse magnetic field attenuates the magnetic flux MF with an abnormally high magnetic flux density caused by the abnormal operation, thereby preventing the magnetic flux MF with an abnormally high magnetic flux density from passing through permanent magnet 320. In this way, the demagnetization resistance of motor 100 is improved.
[0061] On the other hand, when the magnetic flux MF passing through the soft magnetic plate 330 changes, eddy currents are generated in the soft magnetic plate 330 due to electromagnetic induction. In particular, when a magnetic flux MF with an abnormally high magnetic flux density is generated during abnormal operation of the motor 100, excessive eddy currents are generated in the soft magnetic plate 330, which may cause the soft magnetic plate 330 to heat up. This may result in the heat of the soft magnetic plate 330 being transferred to the permanent magnet 320, causing thermal demagnetization of the permanent magnet 320. In this regard, the soft magnetic plate 330 is disposed away from the permanent magnet 320. Therefore, the permanent magnet 320 is less susceptible to the heat generated by the soft magnetic plate 330. This also suppresses thermal demagnetization of the permanent magnet 320. As described above, the rotor 300 of this embodiment improves the demagnetization resistance of the motor 100 and suppresses thermal demagnetization of the permanent magnet 320.
[0062] <Evaluation method for demagnetization resistance> 9 to 13. The method for evaluating the demagnetization resistance will be described. In the method for evaluating the demagnetization resistance, a demagnetization current is passed through the motor to evaluate the demagnetization resistance of the motor.
[0063] In step 1, a motor for which demagnetization resistance is to be evaluated is prepared. Here, motor 400 is illustrated in Fig. 9 as an example of a motor for which demagnetization resistance is to be evaluated. Motor 400 includes winding 410, stator core 420 around which winding 410 is wound, permanent magnet 430, and rotor core 440 on which permanent magnet 430 is disposed.
[0064] In step 2, the induced voltage of motor 400 before the demagnetization current is measured. With windings 410 of motor 400 not connected to external power supply 500, motor 400 is rotated at a predetermined rotation speed, and the induced voltage corresponding to one electrical angle cycle is measured. The induced voltage measured in step 2 corresponds to the induced voltage before motor 400 is demagnetized.
[0065] 10, windings 410 of motor 400 are connected to external power supply 500. This connection causes current to flow through U-phase winding 410, V-phase winding 410, and W-phase winding 410.
[0066] In step 4, a current having a pulse waveform as shown in Fig. 11 is passed from the external power supply 500 to the motor 400. The current passed in step 4 is a demagnetizing current.
[0067] In step 5, the induced voltage of motor 400 after the demagnetization current is measured. First, windings 410 of motor 400 are disconnected from external power supply 500 to release the connection between windings 410 of motor 400 and external power supply 500. After motor 400 is disconnected from external power supply 500, the induced voltage corresponding to one electrical angle cycle when motor 400 is rotated at a predetermined rotation speed is measured. The induced voltage measured in step 5 corresponds to the induced voltage after motor 400 is demagnetized. FIG. 12 illustrates the induced voltage measured in step 2 and the induced voltage measured in step 5.
[0068] In step 6, the demagnetization factor of motor 400 is calculated from the induced voltage measured in step 2 and the induced voltage measured in step 5. The demagnetization factor is calculated as the ratio of the induced voltage measured in step 5 to the induced voltage measured in step 2. In one example, the demagnetization factor is a value of 100% or less.
[0069] In step 7, steps 3 to 6 are repeated with the demagnetizing current increased until the amount of decrease in the demagnetizing factor calculated in step 6 reaches a predetermined value. When the demagnetizing factor calculated in step 6 reaches the predetermined value, the value of the current passed through motor 400 as the demagnetizing current is obtained as the demagnetization resistance of motor 400. Fig. 13 illustrates the amount of decrease in the demagnetizing factor relative to the demagnetizing current.
[0070] In addition, when the applicant measured the demagnetization resistance of the motor 100 of the embodiment, it was confirmed that the demagnetization resistance was improved by approximately 5% while maintaining torque performance compared to a conventional product that did not include the soft magnetic plate 330.
[0071] <Evaluation method for eddy current loss> A method for evaluating the eddy current loss of the soft magnetic plate 330 and the rotor core 310 will be described. According to step 3 of the above-described method for evaluating demagnetization resistance, the motor 100 of this embodiment is connected to the external power supply 500 of FIG. 10. According to step 4, a current having a pulsed waveform as shown in FIG. 14(a) is passed from the external power supply 500 to the motor 100, whereby eddy current loss occurs in each of the soft magnetic plate 330 and the rotor core 310 as shown in FIG. 14(c). The magnitude of the eddy current loss can be measured using an ammeter, wattmeter, or the like. This evaluation method reveals that the eddy current loss per unit volume of the soft magnetic plate 330 of this embodiment is greater than the eddy current loss per unit volume of the rotor core 310.
[0072] <Effects> The effects of this embodiment will be described. (1) Rotor core 310 is provided with first slots 313 and second slots 314. Permanent magnets 320 are housed in first slots 313. Second slots 314 house soft magnetic plates 330 at positions spaced apart from first slots 313. When the magnetic field changes, the eddy current loss per unit volume generated in soft magnetic plate 330 is greater than the eddy current loss per unit volume generated in rotor core 310. In other words, soft magnetic plate 330 is different from rotor core 310, which is made of electromagnetic steel plates. Furthermore, soft magnetic plate 330 generates eddy currents when magnetic flux MF with an abnormally high magnetic flux density is generated, in order to protect permanent magnets 320 from magnetic flux MF with an abnormally high magnetic flux density.
[0073] According to this configuration, the soft magnetic plate 330 is inserted into a slot separate from the permanent magnet 320, so even if the soft magnetic plate 330 generates heat due to eddy currents generated by abnormal changes in the magnetic field, the heat is not easily transferred from the soft magnetic plate 330 to the permanent magnet 320. Since heat transfer from the soft magnetic plate 330 to the permanent magnet 320 is suppressed, the effect of abnormal changes in the magnetic field on the permanent magnet 320 can be suppressed.
[0074] Furthermore, since the soft magnetic plates 330 are inserted into slots separate from the permanent magnets 320, it is easy to arrange the soft magnetic plates 330 in the rotor core 310. This allows for greater freedom in designing the rotor 300.
[0075] (2) With respect to the rotation axis AC, the soft magnetic plate 330 is disposed radially outward of the permanent magnet 320.
[0076] The magnetic flux MF of the magnetic field is formed from the teeth 213 of the stator 200, around which the windings 220 are wound, to the rotor 300. With this configuration, the soft magnetic plate 330 is disposed closer to the teeth 213 than the permanent magnet 320, so that the magnetic flux MF of the magnetic field passing through the soft magnetic plate 330 can be increased.
[0077] (3) In a plane perpendicular to the rotation axis AC, the length of the surface of the soft magnetic plate 330 extending in the longitudinal direction is shorter than the length of the surface of the permanent magnet 320 extending in the longitudinal direction.
[0078] According to this configuration, in a plane perpendicular to the rotation axis AC, the length of the surface of the soft magnetic plate 330 extending in the longitudinal direction is shorter than the length of the surface of the permanent magnet 320 extending in the longitudinal direction. This allows the soft magnetic plate 330 to be smaller than the permanent magnet 320. Making the soft magnetic plate 330 smaller makes it easier to arrange the soft magnetic plate 330 on the rotor core 310, thereby improving the degree of freedom in designing the rotor 300.
[0079] (4) The soft magnetic plate 330 has a first soft magnetic plate 331 and a second soft magnetic plate 332. The first soft magnetic plate 331 is passed by the magnetic flux MF of the magnetic field that passes through the first end 321 of the permanent magnet 320. The second soft magnetic plate 332 is passed by the magnetic flux MF of the magnetic field that passes through the second end 322 of the permanent magnet 320. The first soft magnetic plate 331 and the second soft magnetic plate 332 are provided at a distance from each other in the circumferential direction of the rotation axis AC.
[0080] According to this configuration, the first soft magnetic plate 331, through which the magnetic flux MF passing through the first end 321 passes, and the second soft magnetic plate 332, through which the magnetic flux MF passing through the second end 322 passes, are provided at a distance from each other in the circumferential direction. Therefore, the magnetic flux MF passing between the first soft magnetic plate 331 and the second soft magnetic plate 332 is less affected by the first soft magnetic plate 331 and the second soft magnetic plate 332. The magnetic flux MF of the magnetic field that rotates the rotor 300 passes between the first soft magnetic plate 331 and the second soft magnetic plate 332, thereby maintaining the torque performance of the rotor 300.
[0081] (5) With respect to the rotation axis AC, the soft magnetic plate 330 is disposed radially inward of the permanent magnet 320.
[0082] According to this configuration, the number of magnetic fluxes MF passing through the soft magnetic plate 330 in the magnetic field for rotating the rotor 300 can be reduced, and therefore a decrease in the torque performance of the motor 100 including the rotor 300 can be suppressed.
[0083] (6) The soft magnetic plate 330 is arranged such that the surface of the soft magnetic plate 330 extending in the longitudinal direction intersects with the magnetic flux MF of the magnetic field in a plane perpendicular to the rotation axis AC.
[0084] According to this configuration, the magnetic flux MF of the magnetic field passes through the surface extending in the longitudinal direction of the soft magnetic plate 330, and therefore the magnetic flux MF of the magnetic field passing through the soft magnetic plate 330 can be increased.
[0085] (7) The thickness of the soft magnetic plate 330 is not less than 0.2 mm and not more than 0.5 mm.
[0086] According to this configuration, the thickness of the soft magnetic plate 330 is 0.2 mm or more, which makes it easy to handle the soft magnetic plate 330. Furthermore, the thickness of the soft magnetic plate 330 is 0.5 mm or less, which improves the degree of freedom in arranging the soft magnetic plate 330.
[0087] (8) The motor 100 includes a rotor 300 and a stator 200.
[0088] With this configuration, even if an abnormal change in the magnetic field occurs in the motor 100, the motor 100 is less susceptible to the influence of the abnormal change in the magnetic field. As a result, a decrease in the torque performance of the motor 100 can be suppressed.
[0089] (9) The compressor 10 includes a motor 100 .
[0090] According to this configuration, the deterioration of the torque performance of the motor 100 is suppressed, and therefore the compressor 10 can operate stably.
[0091] (10) The refrigeration device 1 includes a compressor 10.
[0092] According to this configuration, the compressor 10 can operate stably, and the operation of the refrigeration device 1 can be continued in a favorable manner.
[0093] <Modification> In addition to the above-described embodiments, the refrigeration device 1, compressor 10, motor 100, and rotor 300 of the present disclosure may also be configured in the following modified examples, or in a form that combines at least two modified examples that are not mutually contradictory.
[0094] <Example of soft magnetic plate arrangement> 15 to 18. The arrangement of soft magnetic plate 330 on rotor core 310 can be changed as desired. In the example of FIG. 15, soft magnetic plate 330 is arranged between outer peripheral surface 301 of rotor core 310 and permanent magnet 320. Soft magnetic plate 330 is arranged on magnetic flux MF between outer peripheral surface 301 of rotor core 310 and permanent magnet 320. In this modification, in a plane perpendicular to rotation axis AC, the length of the surface of soft magnetic plate 330 extending in the longitudinal direction is longer than the length of the surface of permanent magnet 320 extending in the longitudinal direction. By arranging soft magnetic plate 330 in this manner, the effect of abnormal changes in the magnetic field on permanent magnet 320 can be suppressed.
[0095] 16, a soft magnetic plate 330 is disposed between the inner circumferential surface 302 of the rotor core 310 and the permanent magnet 320. The soft magnetic plate 330 is disposed on the magnetic flux MF between the inner circumferential surface 302 of the rotor core 310 and the permanent magnet 320. The soft magnetic plate 330 of this modification corresponds to the third soft magnetic plate 333 of the embodiment. This modification corresponds to the embodiment from which the first soft magnetic plate 331 and the second soft magnetic plate 332 are omitted. By disposing the soft magnetic plate 330 in this manner, it is possible to improve the demagnetization resistance of the motor 100 while maintaining the torque performance of the motor 100.
[0096] 17 , a soft magnetic plate 330 is disposed between the outer peripheral surface 301 of the rotor core 310 and the permanent magnet 320. The soft magnetic plate 330 is disposed on the magnetic flux MF between the outer peripheral surface 301 of the rotor core 310 and the first end 321 and the second end 322 of the permanent magnet 320. The soft magnetic plate 330 of this modification corresponds to the first soft magnetic plate 331 and the second soft magnetic plate 332 of the embodiment. This modification corresponds to the embodiment in which the third soft magnetic plate 333 is omitted. By disposing the soft magnetic plate 330 in this manner, it is possible to reduce the amount of electromagnetic steel sheet that constitutes the soft magnetic plate 330 while suppressing the effect of abnormal changes in the magnetic field on the permanent magnet 320.
[0097] 18, the soft magnetic plate 330 is arranged so that the longitudinal direction of the soft magnetic plate 330 is aligned with the radial direction in a plane perpendicular to the rotation axis AC. The soft magnetic plate 330 is arranged on the magnetic flux MF between the two permanent magnets 320. By arranging the soft magnetic plate 330 in this manner, it is possible to reduce the amount of electromagnetic steel sheet that constitutes the soft magnetic plate 330 while suppressing the effect of abnormal changes in the magnetic field on the permanent magnet 320.
[0098] The arrangement of the soft magnetic plates 330 on the rotor core 310 may be changed as desired in addition to the examples shown in Figures 15 to 18. In a plane perpendicular to the rotation axis AC, the total length of the surfaces of the soft magnetic plates 330 extending in the longitudinal direction may be smaller than the length of the surfaces of the permanent magnets 320 extending in the longitudinal direction.
[0099] <Other variations> In the embodiment, the rotor 300 includes multiple soft magnetic plates 330, but the rotor core 310 may include only one soft magnetic plate 330. Even with only one soft magnetic plate 330, the influence of abnormal changes in the magnetic field on the permanent magnets 320 can be suppressed.
[0100] The thickness of the soft magnetic plate 330 may be less than 0.2 mm or more than 0.5 mm. The soft magnetic plate 330 may be made of a material other than the electromagnetic steel plate of the rotor plate 311. For example, the soft magnetic plate 330 may be made of an iron-based amorphous material.
[0101] A plurality of soft magnetic plates 330 may be arranged in one second slot 314. According to this modification, a plurality of soft magnetic plates 330 can be arranged in combination to match the shape of the second slot 314.
[0102] The rotor core 310 may be made of a powder magnetic core. By making the rotor core 310 of a powder magnetic core, when the magnetic field changes, the eddy current loss per unit volume generated in the soft magnetic plate 330 can be made larger than the eddy current loss per unit volume generated in the rotor core 310.
[0103] The refrigeration device 1 may be an air conditioner. The air conditioner may be a dedicated cooling device, a dedicated heating device, or a heating / cooling device that can switch between cooling and heating. A heating / cooling air conditioner has a switching mechanism such as a four-way switching valve that switches the refrigerant circulation direction. The refrigeration device 1 may also be a water heater, a chiller unit, a cooling device that cools the air inside a refrigerator, etc.
[0104] While the embodiments of the refrigeration system 1, compressor 10, motor 100, and rotor 300 have been described above, it will be understood that various modifications in form and details are possible without departing from the spirit and scope of the refrigeration system 1, compressor 10, motor 100, and rotor 300 as set forth in the claims. [Explanation of symbols]
[0105] 1...refrigeration device, 10...compressor, 100...motor, 200...stator, 300...rotor, 310...rotor core, 313...first slot, 314...second slot, 320...permanent magnet, 321...first end, 322...second end, 330...soft magnetic plate, 331...first soft magnetic plate, 332...second soft magnetic plate.
Claims
1. A rotor (300) of the motor (100) rotates around a rotation axis (AC) by a magnetic field generated by a stator (200) of the motor (100), A rotor core (310); A permanent magnet (320) disposed in the rotor core (310) and through which the magnetic flux (MF) of the magnetic field passes; a soft magnetic plate (330) disposed in the rotor core (310) and through which the magnetic flux (MF) passing through the permanent magnet (320) passes; When the magnetic field changes, the eddy current loss per unit volume generated in the soft magnetic plate (330) is greater than the eddy current loss per unit volume generated in the rotor core (310), The rotor core (310) is provided with a first slot (313) in which the permanent magnet (320) is housed, and a second slot (314) in which the soft magnetic plate (330) is housed at a position spaced apart from the first slot (313). Rotor.
2. With respect to the rotation axis (AC), the soft magnetic plate (330) is arranged radially outward of the permanent magnet (320). The rotor of claim 1 .
3. In a plane perpendicular to the rotation axis (AC), the length of the surface of the soft magnetic plate (330) extending in the longitudinal direction is shorter than the length of the surface of the permanent magnet (320) extending in the longitudinal direction. The rotor of claim 1 .
4. The soft magnetic plate (330) is a first soft magnetic plate (331) through which the magnetic flux (MF) passing through the first end (321) of the permanent magnet (320) passes; a second soft magnetic plate (332) through which the magnetic flux (MF) passes, the second soft magnetic plate (332) passing through a second end (322) of the permanent magnet (320) opposite to the first end (321); The first soft magnetic plate (331) and the second soft magnetic plate (332) are spaced apart from each other in the circumferential direction of the rotation axis (AC). The rotor of claim 1 .
5. With respect to the rotation axis (AC), the soft magnetic plate (330) is arranged radially inward of the permanent magnet (320). The rotor of claim 1 .
6. The soft magnetic plate (330) is arranged such that a surface extending in the longitudinal direction of the soft magnetic plate (330) intersects with the magnetic flux (MF) in a plane perpendicular to the rotation axis (AC). The rotor of claim 1 .
7. The thickness of the soft magnetic plate (330) is 0.2 mm or more and 0.5 mm or less. The rotor of claim 1 .
8. The rotor (300) according to any one of claims 1 to 7; and the stator (200) that generates the magnetic field that rotates the rotor (300) around the rotation axis (AC). Motor.
9. The motor (100) according to claim 8, Compressor.
10. The compressor (10) according to claim 9, Refrigeration equipment.
Citation Information
Patent Citations
Rotor for permanent magnet embedded rotary electric machine, and rotary electric machine
JP2016005356A