Stator and variable flux motor

Abstract

The invention provides a stator and a variable flux motor. Provided is a stator in which a winding is concentrated, the stator comprising a winding, a plurality of main magnetic poles, and an auxiliary magnetic pole, the winding being wound around the plurality of main magnetic poles, the auxiliary magnetic pole being provided between the plurality of main magnetic poles, the stator being configured such that when the auxiliary magnetic pole is magnetically saturated at a high load, the auxiliary magnetic pole is magnetically saturated at a lower load, and the auxiliary magnetic pole is magnetically saturated at a higher load than when the auxiliary magnetic pole is magnetically saturated at a lower load. And the interlinking magnetic flux of the winding is increased.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS This application is based on Japanese Patent Application No. 2024-026495 filed with the Japan Patent Office on February 26, 2024, and the entire contents of the Japanese Patent Application are hereby incorporated by reference. Technical Field

[0001] The present disclosure relates to a stator and a variable flux motor. Background Art

[0002] A variable flux motor has been proposed, which achieves a variable flux effect by varying the excitation magnetic flux during motor operation. For example, the variable flux motor disclosed in Japanese Patent Application Laid-Open No. 2017-17783 includes a bypass channel that allows a portion of the permanent magnet's magnetic flux to escape toward the rotor, in order to improve efficiency under both low and high load conditions. Summary of the Invention

[0003] The stator of this embodiment is a concentrated winding stator, including a winding, a plurality of main magnetic poles and an auxiliary magnetic pole. The winding is wound around the plurality of main magnetic poles, and the auxiliary magnetic poles are arranged between the plurality of main magnetic poles. The stator is constructed so that when the auxiliary magnetic poles are magnetically saturated under high load, the cross-linkage magnetic flux of the winding increases compared to under low load. BRIEF DESCRIPTION OF THE DRAWINGS

[0004] Figure 1 It is a horizontal cross-sectional view perpendicular to the rotation axis of the electric motor of the reference example. Figure 2 It is a horizontal cross-sectional view perpendicular to the rotation axis of the electric motor according to the present embodiment. Figure 3 This is an efficiency map of a motor as a reference example. Figure 4 This is the efficiency map of the electric motor according to this embodiment. Figure 5 Graph showing the magnetic flux density distribution of a motor according to a reference example. Figure 6 Graphs showing magnetic flux density distribution of the electric motor according to this embodiment. Figure 7 This is a horizontal cross-sectional view perpendicular to the rotation axis of a motor according to another embodiment. DETAILED DESCRIPTION In the following detailed description, for purposes of illustration, numerous specific details are set forth in order to provide a thorough understanding of the disclosed embodiments. However, it will be apparent that one or more embodiments may be practiced without these specific details. In other instances, well-known structures and devices are schematically shown for simplicity of drawing.

[0005] However, the variable-flux motor disclosed in Japanese Patent Application Laid-Open No. 2017-17783 includes a bypass channel in the rotor. This requires consideration of the centrifugal force exerted on the rotor during operation, limiting design freedom. Therefore, a variable-flux motor with a stator featuring a variable-flux structure is desired.

[0006] The present disclosure aims to provide a stator having a variable magnetic flux structure that has high efficiency both under low load and high load conditions, and also aims to provide a variable magnetic flux motor having the stator.

[0007] A concentrated winding stator according to one aspect of the present embodiment includes a concentrated winding stator including a winding, a plurality of main magnetic poles, and auxiliary magnetic poles. The winding is wound around the plurality of main magnetic poles, and the auxiliary magnetic poles are arranged between the plurality of main magnetic poles. The stator is configured such that when the auxiliary magnetic poles are magnetically saturated under high load, the interlinkage magnetic flux of the winding increases compared to under low load.

[0008] A variable magnetic flux motor according to one aspect of the present embodiment includes the above-described stator and a rotor.

[0009] According to the present embodiment, it is possible to provide a stator including a variable magnetic flux structure that has high efficiency both under low load and under high load, and a variable magnetic flux motor including the stator.

[0010] Below, the present embodiment is described with reference to the accompanying drawings. In addition, in the description of the embodiment, for convenience, the description of the components with the same reference numerals as the components already described is omitted. In addition, for ease of description, the dimensions of the components shown in the accompanying drawings may sometimes differ from the actual dimensions of the components.

[0011] Reference Example In order to explain the details of the motor 100 of this embodiment, as a comparison object, Figure 1 A motor 100 ′ according to a reference example will be described.

[0012] Figure 1 1 is a horizontal cross-sectional view perpendicular to the rotation axis of a motor 100 ′ according to a reference example. Figure 1 The illustrated motor 100' has a three-phase, four-pole, six-slot, concentrated winding, and an IPMSM (Inlaid Magnet Synchronous Motor) structure with q = 0.5 slots per pole per phase. The rotary excitation motor 100' includes a stator 10' and a rotor 20 rotatable relative to the stator 10'.

[0013] The stator 10' comprises an annular stator core 11. The stator core 11 is formed by rotating the stator core in the direction of the rotation axis ( Figure 1The stator core 11 is formed of a plurality of electromagnetic steel plates stacked on top of each other (in a direction perpendicular to the paper). The stator core 11 is made of a soft magnetic body and includes an annular yoke portion 11b and six main magnetic pole portions (teeth) 11a. The main magnetic pole portion (teeth) 11a is a portion that protrudes from the radial inner side of the yoke portion 11b and is roughly T-shaped when viewed from above. The six main magnetic pole portions 11a have substantially the same shape as each other and are supported by the yoke portion 11b. A slot is provided between two adjacent main magnetic pole portions 11a. A stator coil 12 is assembled in each slot.

[0014] Each stator coil 12 is wound around the main magnetic pole portion 11a using concentrated winding. An alternating current is applied to the stator coil 12 from the outside. The phases of the currents flowing through the two parts of the stator coil 12 separated by the main magnetic pole portion 11a are reversed. For example, a U-reversed phase or U-phase flows through each of the two parts 12a and 12b of the stator coil 12 separated by the main magnetic pole portion 11a. In addition, a gap portion 13' is provided between adjacent stator coils 12 (for example, between parts 12b and 12c). No components exist in the gap portion 13'. The gap portion 13' is occupied by air.

[0015] The rotor 20 includes a rotor core 21 formed from a plurality of electromagnetic steel sheets stacked in the direction of the rotation axis. The rotor core 21 is cylindrical. A shaft mounting hole 22 is defined on the inner circumference of the rotor core 21. A drive shaft (not shown) is secured to the shaft mounting hole 22. The drive shaft is supported by a housing (not shown) so as to be rotatable about a rotation center O.

[0016] The rotor 20 includes a plurality of rotor magnets 23 arranged in the rotor core 21. The rotor magnets 23 are composed of cylindrical permanent magnets embedded in the slots. The plurality of rotor magnets 23 have approximately the same size, material, and composition. In addition, the plurality of rotor magnets 23 are arranged to form four different poles positioned at 90° angles relative to each other on a circumference centered on the rotation center O. In this way, the plurality of rotor magnets 23 are arranged at equal intervals along the circumference. Therefore, the plurality of rotor magnets 23 generate approximately the same magnetomotive force relative to the stator coil 12. In addition, rotor gaps 24 extending radially outward from the rotor core 21 are provided at both ends of each of the plurality of rotor magnets 23. There are no components inside the rotor gaps 24. The inside of the rotor gaps 24 is occupied by air.

[0017] This embodiment Figure 2 1 is a horizontal cross-sectional view perpendicular to the rotation axis of the motor 100 of this embodiment. Figure 1 The structure of the motor 100 ′ of the reference example shown is different from that of the motor 100 ′.

[0018] The stator core 11 is composed of two or more soft magnetic materials having mutually different magnetic properties. Specifically, the yoke portion 11b and the main magnetic pole portion 11a included in the stator core 11 are composed of a single soft magnetic material. On the other hand, the auxiliary magnetic pole portion 13 included in the stator core 11 is composed 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 portion that protrudes radially inward from the yoke portion 11b and is roughly T-shaped when viewed from above. The auxiliary magnetic pole portion 13 is provided in the gap portion 13' between two adjacent stator coils 12.

[0019] For example, electromagnetic steel sheets can be used as the main magnetic pole portion 11a. For example, a powdered iron core obtained by compression molding Ni-Fe alloy (Permalloy) magnetic powder can be used as the auxiliary magnetic pole portion 13. Alternatively, a magnetic composite material obtained by heat-curing a polymer resin mixed with Permalloy magnetic powder can be used.

[0020] The soft magnetic material constituting the main magnetic pole portion 11a and the soft magnetic material constituting the auxiliary magnetic pole portion 13 are different from each other. Therefore, the saturation magnetization of the main magnetic pole portion 11a and the saturation magnetization of the auxiliary magnetic pole portion 13 are different from each other. Here, the saturation magnetization of the soft magnetic material constituting the main magnetic pole portion 11a is defined as Ms1. In addition, the saturation magnetization of the soft magnetic material constituting the auxiliary magnetic pole portion 13 is defined as Ms2. Therefore, the relationship of Ms1>Ms2 preferably holds. When the above relationship holds, when the motor 100 is highly loaded, even if the current value is started to be supplied, the main magnetic pole portion 11a will not reach the saturation magnetization Ms1. However, the auxiliary magnetic pole portion 13 reaches the saturation magnetization Ms2. Therefore, the magnetic flux passing through the main magnetic pole portion 11a increases. As a result, under high load, the interlinkage flux of the stator coil 12 increases. As a result, the torque T of the motor 100 can be increased. In this embodiment, a high load is defined as a load that is 50% or more of the maximum torque of the motor 100. In addition, a low load is defined as a load of 50% or less of the maximum torque of the motor 100 .

[0021] Furthermore, the relative magnetic permeability of the main magnetic pole portion 11a and the relative magnetic permeability of the auxiliary magnetic pole portion 13 also differ from each other. Here, the relative magnetic permeability of the soft magnetic material constituting the main magnetic pole portion 11a is defined as μr1. Furthermore, the relative magnetic permeability of the soft magnetic material constituting the auxiliary magnetic pole portion 13 is defined as μr2. Thus, the relationship μr1 < μr2 preferably holds. In the structure of the motor 100 of this embodiment, the auxiliary magnetic pole portion 13 is disposed in the gap portion 13'. Therefore, compared to the motor 100' of the reference example, the winding area of ​​the stator coil 12 is reduced by the amount of the auxiliary magnetic pole portion 13. Consequently, the coil space factor is reduced. Consequently, the copper loss of the motor increases. Therefore, to suppress the reduction in the coil space factor, the auxiliary magnetic pole portion 13 preferably has a shape having a narrow width in the circumferential direction of the yoke portion 11b. Furthermore, when the auxiliary magnetic pole portion 13 has a narrow width in the circumferential direction, it is difficult to induce magnetic flux from the rotor magnet 23. Therefore, within the variable magnetic flux range, the auxiliary magnetic pole portion 13 preferably has a high relative magnetic permeability μr2 so that sufficient magnetic flux is induced from the rotor magnet 23 and the relationship μr1 < μr2 holds.

[0022] Furthermore, when the motor 100 is under low load, the main magnetic pole portion 11a does not reach the saturation magnetization Ms1. Furthermore, the auxiliary magnetic pole portion 13 does not reach the saturation magnetization Ms2. Therefore, a portion of the magnetic flux from the rotor magnet 23 passes through the auxiliary magnetic pole portion 13, generating leakage magnetic flux. As a result, the induced voltage generated in the stator coil 12 is reduced, reducing the weak magnetic current. That is, when the motor 100 is under low load, in addition to the main magnetic pole portion 11a, the magnetic flux also passes through the auxiliary magnetic pole portion 13. Therefore, although Figure 2 The number of slots in the stator 10 shown is not physically increased, but from a functional perspective, the stator 10 operates as if the number of slots were increased. Figure 2 The stator 10 shown is Figure 1 Compared to the stator 10 ′ shown, the stator functions as a three-phase, four-pole, twelve-slot stator having twice the number of slots.

[0023] Furthermore, when the motor 100 is under high load, the main magnetic pole portion 11a does not reach the saturation magnetization Ms1, while the auxiliary magnetic pole portion 13 reaches the saturation magnetization Ms2. Therefore, the magnetic flux from the rotor magnet 23 passing through the auxiliary magnetic pole portion 13 does not increase. As a result, the magnetic flux passing through the main magnetic pole portion 11a does not decrease. Moreover, the interlinkage magnetic flux of the stator coil 12 increases compared to the low load condition, thereby increasing the torque T of the motor 100. In other words, Figure 2 The stator 10 shown is Figure 1 The stator 10 ′ shown similarly functions as a stator including three phases, four poles and six slots.

[0024] Thus, by providing the auxiliary magnetic pole portion 13 in the stator 10 , the motor 100 functions as a variable magnetic flux motor having a variable magnetic flux structure.

[0025] In addition, the winding coefficient of three-phase four-pole six-slot is defined as kw1. In addition, the winding coefficient of three-phase four-pole twelve-slot is defined as kw2. Therefore, when the load of the motor 100 is low, the stator 10 functions as a three-phase four-pole twelve-slot. Therefore, the winding coefficient is kw2. In addition, when the load of the motor 100 is high, the stator 10 functions as a three-phase four-pole six-slot. Therefore, the winding coefficient is kw1. At this time, it is preferable to configure the winding of the stator coil 12 of the stator 10 in such a way that the relationship kw1>kw2 holds. In addition, the winding coefficient is calculated by the product of the distributed winding coefficient and the short-moment winding coefficient. That is, the short-moment winding coefficient is a value determined by the structure of the number of pole pairs and the structure of the number of slots.

[0026] (Efficiency Mapping) The efficiency map of the electric motor 100 according to the present embodiment will be described in comparison with the electric motor 100 ′ according to the reference example. Figure 3 An efficiency map of the electric motor 100 ′ according to the reference example is shown. Figure 4 The efficiency map of the electric motor 100 according to this embodiment is shown in FIG. Figure 3 、 Figure 4 In the diagram, the horizontal axis represents the rotational speed R of the motor. The vertical axis represents the torque T. The shades of the shading in each area of ​​the efficiency map represent the efficiency E of the motor. In addition, the efficiency area shown in the efficiency map is divided into areas defined by contour lines set at every 6% efficiency. For example, in Figure 4 In the efficiency map, a portion of the efficiency region is divided into a high efficiency region A showing an efficiency E of 94% or more and a region B showing an efficiency E of 88% or more and less than 94%.

[0027] like Figure 3 As shown, in the motor 100' of the reference example, the high efficiency region A' remains below 10000 rpm ( Figure 3 In addition, at high speed and low load, that is, in the range of rotation speed R above 10000 rpm ( Figure 3 In the region to the right of the dotted line H'), the interval D' between the two rotational speed boundary lines corresponding to the region B of efficiency E is narrow. This shows that the efficiency E drops sharply as the rotational speed R increases.

[0028] In addition, at low speed and high load, that is, in the range of rotation speed R below 5000 rpm ( Figure 3In the region to the left of the dotted line L), after the torque reaches a point P2' corresponding to the rotation speed R of 4000 rpm, the efficiency E starts to decrease.

[0029] In contrast, Figure 4 As shown, in the motor 100 of this embodiment, the high efficiency region A is extended to the range of the rotation speed R below 12200 rpm ( Figure 4 In addition, at high speed and low load, that is, in the range of rotation speed R above 10000 rpm ( Figure 4 In the area to the right of the dotted line H'), the interval D between the two rotational speed boundary lines corresponding to the area B of efficiency E is greater than Figure 3 Therefore, as the rotation speed R increases, the efficiency E decreases more slowly.

[0030] In addition, at low speed and high load, that is, in the range of rotation speed R below 5000 rpm ( Figure 4 The efficiency E remains constant within the region to the left of the dotted line L. Thus, after the torque reaches point P2 corresponding to the rotation speed R of 6000 rpm, the efficiency E begins to decrease more slowly.

[0031] Therefore, the motor 100 of the present embodiment has higher efficiency E at low load and high load times than the motor 100 ′ of the reference example.

[0032] (Magnetic flux density distribution) The magnetic flux density distribution of the motor 100 according to the present embodiment will be described in comparison with the motor 100 ′ according to the reference example. Figure 5 Magnetic flux density distribution of the motor 100 ′ according to the reference example under high load is shown. Figure 6 : shows the magnetic flux density distribution of the motor 100 of this embodiment under high load. Figure 5 、 Figure 6 In the diagram, the distribution of magnetic flux density is represented by the shade of the shadow. Figure 5 、 Figure 6 In the horizontal cross-sectional view of the motor 100, 100', the rotor 20 is Figure 1 、 Figure 2 The horizontal cross-section of the electric motor 100 , 100 ′ is shown offset by 45° in the direction of rotation.

[0033] like Figure 5As shown, in the reference example motor 100', the gap portion 13' is occupied by air. Therefore, the relative magnetic permeability is as low as 1. Therefore, the magnetic flux from the rotor magnet 23 hardly passes through the gap portion 13'. In addition, the magnetic flux from the rotor magnet 23 is concentrated on the main magnetic pole portion 11a. Therefore, no leakage magnetic flux from the rotor magnet 23 is generated. As a result, since the induced voltage generated in the stator coil 12 does not decrease, the weak magnetic current is not reduced. Therefore, the interlinkage magnetic flux of the stator coil 12 does not increase. As a result, the torque T of the motor 100 does not increase.

[0034] In contrast, Figure 6 As shown, in the motor 100 of this embodiment, auxiliary magnetic pole portions 13 having a higher relative magnetic permeability μr2 than the gap portions 13' are provided. Therefore, the magnetic flux from the rotor magnets 23 is not concentrated on the main magnetic pole portions 11a. As a result, a portion of the magnetic flux passes through the auxiliary magnetic pole portions 13. This generates leakage flux, reducing the induced voltage generated in the stator coil 12 and the field-weakening current. As a result, the interlinkage flux in the stator coil 12 increases, increasing the torque T of the motor 100.

[0035] Other implementations Figure 7 2 is a horizontal cross-sectional view perpendicular to the rotation axis of the motor 200 according to another embodiment. Figure 2 The structure of the electric motor 100 of the present embodiment shown is different.

[0036] In the above embodiment, an example in which no winding is wound around the auxiliary magnetic pole portion 13 has been described. Figure 7 The auxiliary magnetic pole portions 13 of the illustrated motor 200 are wound with auxiliary windings 14. The auxiliary magnetic pole portions 13 may be made of a soft magnetic material different from that of the main magnetic pole portions 11a. Alternatively, the auxiliary magnetic pole portions 13 may be made of the same magnetic material as the main magnetic pole portions 11a. Auxiliary windings 14, which are separate from the stator coils 12, are wound around the auxiliary magnetic pole portions 13. Therefore, the auxiliary windings 14 are not electrically connected to the stator coils 12 wound around the main magnetic pole portions 11a.

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

[0038] Here, active variable flux operation refers to excitation using power supplied from the power supply circuit connected to the auxiliary winding 14. Specifically, active variable flux operation refers to an action in which the auxiliary magnetic pole portion 13 actively varies its magnetic flux, independent of the torque T of the motor 200. Furthermore, flux enhancement operation is a type of active variable flux operation. More specifically, flux enhancement operation refers to an action in which the magnetic flux passing through the auxiliary magnetic pole portion 13 is increased by excitation using power supplied from the power supply circuit connected to the auxiliary winding 14, thereby increasing the torque T of the motor 200. Furthermore, torque ripple reduction operation is a type of active variable flux operation. More specifically, torque ripple reduction operation refers to an action in which a torque harmonic component of opposite phase to the torque ripple of the motor 200 is superimposed on the torque ripple. Here, the torque harmonic component is generated by excitation using power supplied from the power supply circuit connected to the auxiliary winding 14. This reduces torque ripple.

[0039] The passive variable magnetic flux operation refers to an operation in which the magnetic flux is passively changed with respect to the load by disconnecting the terminals of the power circuit connected to the auxiliary winding 14 and relying solely on the magnetic material properties of the unexcited auxiliary magnetic pole portion 13 .

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

[0041] In this way, the configuration including auxiliary windings 14 wound around auxiliary magnetic pole portions 13, separate from stator coils 12, enables at least three operating modes: active variable flux operation, passive variable flux operation, and energy regeneration. This further improves efficiency under both low and high load conditions.

[0042] As described above, the motor 100 of this embodiment functions as a variable flux motor having a variable flux structure due to the auxiliary magnetic pole portion 13 provided in the stator 10. Therefore, the efficiency can be improved under low load and high load conditions.

[0043] The above describes the present embodiment. However, the technical scope of the present embodiment should not be interpreted as limited by the description of the present embodiment. The described embodiment is only an example. Those skilled in the art will understand that the described embodiment can be modified in various ways within the scope disclosed in the claims. The technical scope of the present embodiment should be determined based on the scope disclosed in the claims and their equivalents. The detailed description has been presented for purposes of illustration and description. Numerous variations and modifications are possible in light of the above teachings. The detailed description is not intended to be exhaustive or to limit the subject matter described herein. Although the subject matter has been described in terms of specific structural features and / or methodological procedures, it should be understood that the subject matter defined in the claims is not necessarily limited to the specific features or procedures described. Rather, the specific features and procedures described are described as examples of implementing the claims.

Claims

1. A stator, which is a concentrated winding stator, wherein: The stator includes a winding, a plurality of main magnetic poles and auxiliary magnetic poles. The winding is wound around the plurality of main magnetic poles, The auxiliary magnetic pole is arranged between the plurality of main magnetic poles, The stator is configured such that when the auxiliary magnetic pole is magnetically saturated under high load, the interlinkage magnetic flux of the winding increases compared to under low load.

2. The stator according to claim 1, wherein: The stator is configured to function as an m-pole 2n-slot armature under low load, and to function as an m-pole n-slot armature through the magnetically saturated auxiliary magnetic poles under high load. The m and the n are natural numbers.

3. The stator according to claim 2, wherein: When the winding coefficient of the m-pole n-slot structure is defined as kw1 and the winding coefficient of the m-pole 2n-slot structure is defined as kw2, the armature winding is arranged so that the relationship kw1>kw2 holds.

4. The stator according to claim 2, wherein: The stator is configured such that, when the saturation magnetization of the soft magnetic material constituting the main magnetic pole is defined as Ms1 and the saturation magnetization of the soft magnetic material constituting the auxiliary magnetic pole is defined as Ms2, a relationship of Ms1>Ms2 holds.

5. The stator according to claim 2, wherein: The stator is configured such that, when the relative magnetic permeability of the soft magnetic material constituting the main magnetic pole is defined as μr1 and the relative magnetic permeability of the soft magnetic material constituting the auxiliary magnetic pole is defined as μr2, a relationship of μr1 < μr2 holds.

6. The stator according to claim 3, wherein: The stator is configured such that, when the relative magnetic permeability of the soft magnetic material constituting the main magnetic pole is defined as μr1 and the relative magnetic permeability of the soft magnetic material constituting the auxiliary magnetic pole is defined as μr2, a relationship of μr1 < μr2 holds.

7. The stator according to claim 1, wherein: An auxiliary winding is wound around the auxiliary magnetic pole.

8. The stator according to claim 7, wherein: The winding of the main magnetic pole and the auxiliary winding can be connected to different circuits.

9. The stator according to claim 7, wherein: The auxiliary magnetic poles can perform either an active variable flux operation or a passive variable flux operation.

10. The stator according to claim 7, wherein: The auxiliary magnetic pole enables a regenerative operation.

11. A variable flux motor, wherein: A device comprising the stator and rotor according to any one of claims 1 to 10.

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