Stator and variable magnetic flux motor

Abstract

To provide a stator which reduces torque ripple while suppressing reduction in torque of a motor, and a motor or a generator.SOLUTION: A stator 10 of concentrated winding comprises a plurality of main magnetic poles 11a around which coils are wound and auxiliary magnetic poles 13 provided between the plurality of main magnetic poles 11a. In the case of high load, the auxiliary magnetic poles 13 are magnetically saturated, thereby increasing interlinkage magnetic flux of the coils than in the case of low load.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a stator and a variable magnetic flux motor. [Background technology]

[0002] Variable magnetic flux motors have been proposed that have a variable magnetic flux effect, which changes the amount of field magnetic flux while the motor is running. For example, Patent Document 1 discloses a variable magnetic flux motor that has a bypass path in the rotor that allows part of the magnetic flux of the permanent magnet to escape, in order to improve efficiency under low and high loads. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2017-17783 Summary of the Invention [Problem to be solved by the invention]

[0004] However, the variable magnetic flux motor disclosed in Patent Document 1 has a bypass path in the rotor, but the degree of freedom in design is limited because it is necessary to consider the centrifugal force strength of the rotor while the motor is running. Therefore, a variable magnetic flux motor with a variable magnetic flux structure in the stator is desired.

[0005] An object of the present invention is to provide a stator with a variable magnetic flux structure that is highly efficient under both low and high loads, and a variable magnetic flux motor equipped with the stator. [Means for solving the problem]

[0006] A concentrated winding stator according to one aspect of the present invention comprises: a plurality of main poles wound with windings; and auxiliary poles provided between the plurality of main poles, When the load is high, the auxiliary pole is magnetically saturated, and the interlinkage magnetic flux of the winding increases more than when the load is low.

[0007] A variable magnetic flux motor according to one aspect of the present invention comprises: The motor comprises the stator and a rotor. [Effects of the Invention]

[0008] According to the present invention, it is possible to provide a stator with a variable magnetic flux structure that is highly efficient under both low load and high load conditions, and a variable magnetic flux motor that includes the stator. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 10 is a horizontal cross-sectional view perpendicular to the rotation axis of a motor according to a reference example. [Figure 2] 1 is a horizontal cross-sectional view taken along a line perpendicular to the rotation axis of a motor according to an embodiment of the present invention. [Figure 3] 10 is an efficiency map of a motor according to a reference example. [Figure 4] 4 is an efficiency map of the motor according to the present embodiment. [Figure 5] FIG. 10 is a diagram showing the magnetic flux density distribution of a motor according to a reference example. [Figure 6] FIG. 4 is a diagram showing a magnetic flux density distribution of the motor according to the embodiment. [Figure 7] FIG. 10 is a horizontal cross-sectional view taken along a line perpendicular to the rotation axis of a motor according to another embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, embodiments of the present invention will be described with reference to the drawings. For the sake of convenience, the description of components having the same reference numerals as those already described in the description of the embodiments will be omitted. Furthermore, for the sake of convenience, the dimensions of each component shown in the drawings may differ from the actual dimensions of each component. [Reference example]

[0011] In order to explain the details of the motor 100 according to this embodiment, a motor 100' according to a reference example will be explained as a comparison example with reference to FIG.

[0012] Fig. 1 is a horizontal cross-sectional view perpendicular to the rotation axis of a motor 100' according to a reference example. The motor 100' shown in Fig. 1 has a three-phase, four-pole, six-slot, concentrated winding IPMSM (interior permanent magnet synchronous motor) structure with a per-pole, per-phase slot number q = 0.5. The motor 100' is also a rotating field type and includes a stator 10' and a rotor 20 that can rotate relative to the stator 10'.

[0013] The stator 10' includes a ring-shaped stator core 11 formed by laminating multiple electromagnetic steel plates in the direction of the rotation axis (perpendicular to the plane of the paper in FIG. 1). The stator core 11 is made of a soft magnetic material and has a ring-shaped yoke portion 11b and six main magnetic pole portions (teeth) 11a. The main magnetic pole portions (teeth) 11a are generally T-shaped in plan view and protrude from the radially inner side of the yoke portion 11b. The six main magnetic pole portions 11a have approximately the same shape and are supported by the yoke portion 11b. Slots are provided between two adjacent main magnetic pole portions 11a, and a stator coil 12 is incorporated in each slot.

[0014] Each stator coil 12 is wound around the main magnetic pole portion 11a by concentrated winding. An AC current is applied to the stator coil 12 from the outside. The two portions of the stator coil 12 separated by the main magnetic pole portion 11a have currents of opposite phase to each other. For example, U-phase and U-phase currents flow through the two portions 12a and 12b of the stator coil 12 separated by the main magnetic pole portion 11a, respectively. Furthermore, a gap 13' is provided between adjacent stator coils 12 (for example, between portions 12b and 12c). There is no material in the gap 13', and air is present.

[0015] The rotor 20 includes a rotor core 21 formed by laminating multiple electromagnetic steel plates in the direction of the rotation axis. The rotor core 21 is formed in a cylindrical shape. The inner peripheral surface of the rotor core 21 defines a shaft mounting hole 22. A drive shaft (not shown) is fixed to the shaft mounting hole 22, and the drive shaft is supported by a housing (not shown) so as to be rotatable about a rotation center O.

[0016] The rotor 20 has a plurality of rotor magnets 23 in the rotor core 21. The rotor magnets 23 are cylindrical permanent magnets embedded inside slots and are substantially identical in size, material, and composition. The plurality of rotor magnets 23 are arranged at equal intervals along a circumference centered on the center of rotation O so as to form four poles that are 90° apart from one another. Therefore, the magnetomotive force acting on the stator coil 12 due to each rotor magnet 23 is substantially the same. A rotor air gap 24 extending radially outward is provided at both ends of each rotor magnet 23. There are no components inside the rotor air gap 24, and air is present instead. [Present embodiment]

[0017] 2 is a horizontal cross-sectional view perpendicular to the rotation axis of the motor 100 according to this embodiment. Only the differences in the configuration from the motor 100' according to the reference example shown in FIG.

[0018] The stator core 11 is made of two or more types of soft magnetic materials with different magnetic properties. Specifically, the stator core 11 includes a yoke portion 11b and a main magnetic pole portion 11a made of a single type of soft magnetic material, and an auxiliary magnetic pole portion 13 made of a soft magnetic material different from that of the yoke portion 11b and the main magnetic pole portion 11a. The auxiliary magnetic pole portion 13 is a generally T-shaped portion in a plan view that protrudes from the radially inner side of the yoke portion 11b, and is provided in a gap portion 13' between two adjacent stator coils 12.

[0019] The main magnetic pole 11a may be made of, for example, an electromagnetic steel plate. The auxiliary magnetic pole 13 may be made of, for example, a dust core made by compressing and molding magnetic powder of a Ni-Fe alloy (permalloy), or a magnetic composite material made by mixing the magnetic powder with a polymer resin and then heat-hardening the mixture.

[0020] The main magnetic pole portion 11a and the auxiliary magnetic pole portion 13 are made of different soft magnetic materials and have different saturation magnetizations. If the saturation magnetization of the soft magnetic material constituting the main magnetic pole portion 11a is defined as Ms1 and the saturation magnetization of the soft magnetic material constituting the auxiliary magnetic pole portion 13 is defined as Ms2, then it is desirable for the relationship Ms1 > Ms2. With this relationship, when the motor 100 is under high load, the main magnetic pole portion 11a does not reach saturation magnetization Ms1 even when current begins to be supplied, but the auxiliary magnetic pole portion 13 reaches saturation magnetization Ms2. Therefore, by increasing the magnetic flux passing through the main magnetic pole portion 11a, the flux linkage of the stator coil 12 increases under high load, thereby increasing the torque T of the motor 100. In this embodiment, a high load is defined as a load equal to or greater than 50% of the maximum torque of the motor 100, and a low load is defined as a load equal to or less than 50% of the maximum torque of the motor 100.

[0021] The main magnetic pole portion 11a and the auxiliary magnetic pole portion 13 also differ in relative permeability. If the relative permeability of the soft magnetic material constituting the main magnetic pole portion 11a is defined as μr1 and the relative permeability of the soft magnetic material constituting the auxiliary magnetic pole portion 13 is defined as μr2, then it is desirable for the relationship μr1<μr2 to be satisfied. In the motor 100 according to this embodiment, the auxiliary magnetic pole portion 13 is disposed in the air gap portion 13'. Therefore, compared to the motor 100' according to the reference example, the winding area of ​​the stator coil 12 is reduced by the amount of the auxiliary magnetic pole portion 13, resulting in a decrease in the coil space factor and increased copper loss in the motor. Therefore, to prevent a decrease in the coil space factor, it is desirable for the auxiliary magnetic pole portion 13 to have a shape with a narrow circumferential width. Furthermore, if the auxiliary magnetic pole portion 13 has a shape with a narrow circumferential width, it becomes difficult to guide the magnetic flux from the rotor magnet 23. Therefore, it is desirable to have a high relative permeability μr2 so that μr1<μr2 so that the magnetic flux from the rotor magnet 23 can be sufficiently guided within the variable magnetic flux range.

[0022] Furthermore, when the motor 100 is under low load, the main magnetic pole portion 11a and the auxiliary magnetic pole portion 13 do not reach saturation magnetization Ms1 and Ms2, respectively, and part of the magnetic flux from the rotor magnet 23 passes through the auxiliary magnetic pole portion 13, generating leakage flux, reducing the induced voltage generated in the stator coil 12 and reducing the field-weakening current. In other words, when the motor 100 is under low load, magnetic flux passes through the auxiliary magnetic pole portion 13 in addition to the main magnetic pole portion 11a, so although the number of slots in the stator 10 shown in Figure 2 does not physically increase, from a functional standpoint, it operates as if the number of slots were increased. The stator 10 shown in Figure 2 functions as a three-phase, four-pole, 12-slot stator, which has twice the number of slots as the stator 10' shown in Figure 1.

[0023] Furthermore, when the motor 100 is under high load, the main magnetic pole portion 11a does not reach saturation magnetization Ms1, and the auxiliary magnetic pole portion 13 reaches saturation magnetization Ms2. Therefore, the magnetic flux passing from the rotor magnet 23 through the auxiliary magnetic pole portion 13 does not increase, and the magnetic flux passing through the main magnetic pole portion 11a does not decrease, resulting in an increase in the flux linkage of the stator coil 12 compared to when the load is low, and a larger torque T of the motor 100. In other words, the stator 10 shown in FIG. 2 functions as a three-phase, four-pole, six-slot structure, similar to the stator 10' shown in FIG. 1.

[0024] In this way, by providing the auxiliary magnetic pole portions 13 on the stator 10, the motor 100 functions as a variable magnetic flux motor having a variable magnetic flux structure.

[0025] If the winding factor for a three-phase, four-pole, six-slot configuration is defined as kw1 and the winding factor for a three-phase, four-pole, twelve-slot configuration is defined as kw2, then when motor 100 is under low load, it functions as a three-phase, four-pole, twelve-slot configuration, and the winding factor is kw2. When motor 100 is under high load, it functions as a three-phase, four-pole, six-slot configuration, and the winding factor is kw1. In this case, it is desirable to arrange the windings of stator coil 12 of stator 10 so that kw1 > kw2. The winding factor is calculated as the product of the distributed winding factor and the short-pitch winding factor, and the short-pitch winding factor is a value determined by the configuration of the number of pole pairs and the number of slots. <Efficiency map>

[0026] An efficiency map of the motor 100 according to this embodiment will be described in comparison with a motor 100' according to a reference example. FIG. 3 shows the efficiency map of the motor 100' according to the reference example. FIG. 4 shows the efficiency map of the motor 100 according to this embodiment. In both FIGS. 3 and 4, the horizontal axis represents the motor rotation speed R, the vertical axis represents the torque T, and the density of each region of the efficiency map represents the motor efficiency E. The efficiency map is divided into regions in 6% increments: a high-efficiency region A where the efficiency E is 94% or higher, and a region B where the efficiency E is 88% or higher but less than 94%.

[0027] As shown in Fig. 3, in motor 100' according to the reference example, high efficiency region A' remains in the range where rotation speed R is 10,000 rpm or less (the region to the left of dashed line H' passing through point P1' in Fig. 3). Also, at high speeds and low loads where rotation speed R is 10,000 rpm or more (the region to the right of dashed line H' in Fig. 3), the width D' of the boundary line of efficiency E is narrow, so efficiency E drops sharply as rotation speed R increases.

[0028] Furthermore, at low speeds and high loads where the rotation speed R is 5000 rpm or less (the region to the left of the dashed line L in FIG. 3), the efficiency E decreases from point P2' where the rotation speed R is 4000 rpm.

[0029] In contrast, as shown in Fig. 4, in motor 100 according to this embodiment, high efficiency region A extends to a range where rotation speed R is 12,200 rpm or less (the region to the left of dashed line H passing through point P1 in Fig. 4). Furthermore, at high speeds and low loads where rotation speed R is 10,000 rpm or more (the region to the right of dashed line H' in Fig. 4), the width D of the boundary line of efficiency E widens, and therefore efficiency E gradually decreases as rotation speed R increases.

[0030] Furthermore, at low speeds and high loads where the rotation speed R is 5000 rpm or less (the area to the left of the dashed line L in Figure 3), the efficiency E is kept constant, and begins to decrease gradually from point P2 where the rotation speed R is 6000 rpm.

[0031] Therefore, compared to the motor 100' according to the reference example, the motor 100 according to this embodiment has a higher efficiency E under low load and high load conditions. <Magnetic flux density distribution>

[0032] The magnetic flux density distribution of the motor 100 according to this embodiment will be described in comparison with that of a motor 100' according to a reference example. FIG. 5 shows the magnetic flux density distribution of the motor 100' according to the reference example under high load. FIG. 6 shows the magnetic flux density distribution of the motor 100 according to this embodiment under high load. Both FIGS. 5 and 6 show the distribution of magnetic flux density B in terms of concentration. For ease of explanation, the horizontal cross-sectional views of the motors 100 and 100' shown in FIGS. 4 and 5 show a state in which the rotor 20 is shifted 45° in the direction of rotation from the horizontal cross-sectional views of the motors 100 and 100' shown in FIGS. 1 and 2.

[0033] As shown in Figure 5, in the motor 100' according to the reference example, the air gap 13' is filled with air, resulting in a low relative permeability of 1. As a result, almost no magnetic flux from the rotor magnet 23 passes through the air gap 13' and is concentrated at the main magnetic pole 11a. As a result, no leakage magnetic flux occurs from the rotor magnet 23, the induced voltage generated in the stator coil 12 does not decrease, and the field-weakening current is not reduced. As a result, the flux linkage of the stator coil 12 does not increase, and the torque T of the motor 100 does not increase.

[0034] 6, the motor 100 according to this embodiment is provided with auxiliary magnetic pole portions 13 having a higher relative permeability μr2 than the air gap portions 13. As a result, the magnetic flux from the rotor magnet 23 does not concentrate on the main magnetic pole portions 11a, and part of the magnetic flux passes through the auxiliary magnetic poles 13, generating leakage flux, reducing the induced voltage generated in the stator coil 12 and reducing the field-weakening current. This increases the flux linkage of the stator coil 12, and increases the torque T of the motor 100. [Other embodiments]

[0035] 7 is a horizontal cross-sectional view perpendicular to the rotation axis of a motor 200 according to another embodiment. Only the differences in configuration from the motor 100 according to this embodiment shown in FIG. 2 will be described below.

[0036] In the above-described embodiment, an example was described in which no winding was wound around the auxiliary magnetic pole portion 13. However, the auxiliary magnetic pole portion 13 of the motor 200 shown in FIG. 7 has an auxiliary winding 14 wound around it. The auxiliary magnetic pole portion 13 may be made of a soft magnetic material different from that of the main magnetic pole portion 12, or may be made of the same magnetic material. The auxiliary magnetic pole portion 13 is wound with an auxiliary winding 14 separate from the stator coil 12. Therefore, the auxiliary winding 14 is not electrically connected to the stator coil 12 wound around the main magnetic pole portion 11a.

[0037] The auxiliary magnetic pole portion 13 has three operation modes: an active variable magnetic flux operation mode, a passive variable magnetic flux operation mode, and an energy regeneration operation mode. The active variable magnetic flux operation may include two operation modes: a flux strengthening operation mode and a torque ripple reduction operation mode.

[0038] Here, active variable magnetic flux operation refers to the operation of the auxiliary magnetic pole portion 13 actively changing the magnetic flux regardless of the torque T of the motor 200 by supplying power from a power supply circuit connected to the auxiliary winding 14 to excite it. Furthermore, the magnetic flux strengthening operation is a type of active variable magnetic flux operation, and refers to an operation in which the auxiliary winding 14 is excited by supplying power from a power supply circuit connected to the auxiliary winding 14, thereby increasing the amount of magnetic flux passing through the auxiliary magnetic pole portion 13 and increasing the torque T of the motor 200. Furthermore, the torque ripple reduction operation is a type of active variable magnetic flux operation, and refers to an operation in which power is supplied from a power supply circuit connected to the auxiliary winding 14 to excite it, thereby generating torque harmonic components that are in opposite phase to the torque ripple of the motor 200 and superimposing them on the torque ripple, thereby reducing the torque ripple.

[0039] Passive variable magnetic flux operation refers to an operation in which the terminals of the power supply circuit connected to the auxiliary winding 14 are opened, so that the auxiliary magnetic pole portion 13 is not excited and the magnetic flux changes passively in response to the load, depending only on the magnetic material characteristics.

[0040] The energy regenerating operation refers to an operation of regenerating the electric power generated in the auxiliary winding 14 by the leakage magnetic flux from the rotor magnet 23 to the power supply of the power supply circuit connected to the auxiliary winding 14 .

[0041] In this way, by configuring the auxiliary magnetic pole portion 13 to be wound with an auxiliary winding 14 separate from the stator coil 12, it is possible to realize at least three operating modes including active variable magnetic flux operation, passive variable magnetic flux operation, and energy regeneration operation, thereby making it possible to further improve efficiency at low loads and high loads.

[0042] As described above, by providing the auxiliary magnetic pole portion 13 on the stator 10, the motor 100 according to this embodiment functions as a variable magnetic flux motor with a variable magnetic flux structure, making it possible to improve efficiency under both low and high loads.

[0043] Although the embodiments of the present invention have been described above, it goes without saying that the technical scope of the present invention should not be construed as being limited by the description of the present embodiments. The present embodiments are merely examples, and it will be understood by those skilled in the art that various modifications of the embodiments are possible within the scope of the invention described in the claims. The technical scope of the present invention should be determined based on the scope of the invention described in the claims and its equivalents. [Explanation of symbols]

[0044] 10, 10': Stator 20: Rotor 11: Stator core 11a: Main magnetic pole part (teeth) 11b: Yoke part 12: Stator coil 13: Auxiliary magnetic pole part 13': Void 14: Auxiliary winding 100, 100', 200: Motor 21: Rotor core 22: Shaft mounting hole 23: Rotor magnet 24: Rotor gap O: Center of rotation

Claims

1. A concentrated winding stator, a plurality of main poles wound with windings; an auxiliary pole provided between a plurality of the main poles; Equipped with The auxiliary magnetic poles are magnetically saturated under high load conditions, thereby increasing the interlinkage magnetic flux of the windings compared to under low load conditions.

2. At low loads, it functions as an m-pole 2n-slot armature. When the load is high, the auxiliary magnetic poles become magnetically saturated, and the armature functions as an m-pole, n-slot armature. The stator according to claim 1 , wherein m and n are natural numbers.

3. The winding factor of the m poles and n slots is kw1, If the winding factor of the m-pole, 2n-slot configuration is defined as kw2, then 3. The stator according to claim 2, wherein the armature windings are arranged so that kw1>kw2.

4. The saturation magnetization of the soft magnetic material constituting the main pole is Ms1, If the saturation magnetization of the soft magnetic material constituting the auxiliary pole is defined as Ms2, then The stator according to claim 2 , wherein Ms1>Ms2.

5. The relative permeability of the soft magnetic material constituting the main pole is μr1, If the relative permeability of the soft magnetic material constituting the auxiliary magnetic pole is defined as μr2, then The stator according to claim 2 , wherein μr1<μr2.

6. The relative permeability of the soft magnetic material constituting the main pole is μr1, If the relative permeability of the soft magnetic material constituting the auxiliary magnetic pole is defined as μr2, then The stator according to claim 3 , wherein μr1<μr2.

7. The stator of claim 1 , wherein the auxiliary poles are wound with auxiliary windings.

8. The stator according to claim 7 , wherein the winding of the main pole and the auxiliary winding are connectable to different circuits.

9. The stator of claim 7 , wherein the auxiliary poles are capable of active variable flux operation and passive variable flux operation.

10. The stator according to claim 7 , wherein the auxiliary pole is capable of regenerative operation.

11. A stator according to any one of claims 1 to 10; A rotor; A variable flux motor comprising:

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