motor

Abstract

A motor is provided. The motor includes a stator including a stator core having teeth and a winding wound around the teeth, and a rotor including a permanent magnet, at least a portion of a portion of the rotor in which the permanent magnet is embedded being provided with a non-magnetic portion opposite the stator.

Description

[0001] Cross-reference of related applications This application is based on Japanese Patent Application No. 2024-211207, filed with the Japan Patent Office on December 4, 2024, the entire contents of which are incorporated herein by reference. Technical Field

[0002] This disclosure relates to a motor. Background Technology

[0003] Most motors are used at a fixed speed in compressor or air supply applications. In recent years, however, the rotational speed of motors has been controlled in various applications. For example, drive motors in hybrid vehicles operate across a wide range of speeds, from low to high. Furthermore, servo system motors, representative of FA (Factory Automation) motors, are driven at high acceleration and deceleration speeds to quickly track position commands. Therefore, high-output or high-speed motors are active in high-end applications. The market for these motors is continuously expanding. Summary of the Invention

[0004] When the rotational speed exceeds a certain value, voltage saturation occurs, where the relationship between the back electromotive force generated in the motor and the power supply voltage reverses. To mitigate voltage saturation, it is advisable to reduce the magnetic flux of the excitation system, which is the cause of the back electromotive force.

[0005] Therefore, it is known to improve torque in the high-speed region by suppressing the back electromotive force of the motor through so-called weak flux control. However, copper losses increase the amount of d-axis current required for weak flux control, thus reducing efficiency. Alternatively, replacing the rotor's permanent magnets with weaker permanent magnets can also be considered to increase torque in the high-speed region. However, in this method, torque at low speeds is reduced. Therefore, for example, Japanese Patent Publication No. 2022-184461 proposes a control model that inserts the inverse model of the motor after the current controller. According to this model, it is possible to improve the instantaneous voltage saturation in the step response.

[0006] The inventors believe that if a motor structure can be realized that suppresses back electromotive force at high speeds without reducing torque at low speeds, then a motor with high torque and high output can be provided over a wide operating range using a general control system.

[0007] Therefore, the purpose of this disclosure is to provide a motor that can suppress back electromotive force at high speeds without reducing torque at low speeds.

[0008] One embodiment of the motor includes: a stator including a stator core having teeth and a winding wound on the teeth; and a rotor including a permanent magnet, wherein at least a portion of the portion of the permanent magnet embedded in the rotor opposite to the stator is provided with a non-magnetic portion.

[0009] In another embodiment of this invention, the motor may have at least a portion of the stator made of a nonlinear soft magnetic material.

[0010] In another embodiment of this motor, the non-magnetic part may be configured to obstruct the magnetic flux along the d-axis relative to the permanent magnet.

[0011] In another embodiment of this invention, the motor may be configured such that the non-magnetic portion is asymmetrically arranged with respect to the d-axis.

[0012] In another embodiment of this motor, the rotor may be composed of a plurality of iron chips, which are stacked in such a way that the positions of the non-magnetic portions of adjacent iron chips are staggered.

[0013] In another embodiment of this motor, the rotor may be composed of a plurality of iron chips, which are stacked in a manner that is symmetrical about the position of the non-magnetic portion of adjacent iron chips with respect to the d-axis. According to another embodiment of this invention, the non-magnetic portion may be configured to extend along the q-axis direction. According to another embodiment of this invention, the non-magnetic portion may have a d-axis magnetic flux barrier extending along the d-axis direction and a q-axis magnetic flux barrier extending along the q-axis direction.

[0014] According to this embodiment, a motor can be provided that can suppress back electromotive force at high speeds without reducing torque at low speeds. The motor according to embodiments of this disclosure includes: a stator including a stator core having teeth and a winding wound on the teeth; and a rotor including a permanent magnet, wherein at least a portion of the portion of the permanent magnet embedded in the rotor opposite to the stator is provided with a non-magnetic portion. Attached Figure Description

[0015] Figure 1 This is a diagram showing the motor 100 according to the first embodiment of this disclosure. Figure 2 It is a graph representing the BH curves of general soft magnetic materials and nonlinear soft magnetic materials. Figure 3 express Figure 1 The efficiency mapping diagram of the motor 100 of the first embodiment is shown. Figure 4 This is a diagram showing motor 200 in Reference Example 1. Figure 5 yes Figure 4 The efficiency mapping diagram of motor 200 is shown. Figure 6 This is a diagram representing motor 300 in Reference Example 2. Figure 7 yes Figure 6 The efficiency mapping diagram of motor 300 is shown. Figure 8 This is a graph showing the magnetic flux density distribution of the motor 200 in Reference Example 1. Figure 9 This is a diagram showing the magnetic flux density distribution of the motor 100 in the first embodiment. Figure 10 This is a graph showing the magnetic flux density distribution of motor 300 in Reference Example 2. Figure 11 This is a diagram showing the rotor 20 of the motor 400 in a modified example of this embodiment. Figure 12 This is a diagram showing the motor 500 according to the second embodiment of this disclosure. Figure 13 express Figure 12 The efficiency mapping diagram of the motor 500 in the second embodiment is shown. Figure 14 This is a diagram showing the magnetic flux density distribution of the motor 500 in the second embodiment. Figure 15 This is a diagram illustrating the motor 600 according to the third embodiment of this disclosure. Figure 16A This is an enlarged view of the motor 200 in Reference Example 1 without the q-axis flux barrier 601. Figure 16B This is an enlarged view of the motor 600 of the third embodiment, which is equipped with a q-axis magnetic flux barrier 601. Figure 17 This is a graph comparing the maximum torque of three types of motors: 200, 600, and 700. Figure 18 This is a diagram showing the torque distribution generated on the surface of the rotor 20 of motor 200 (a), motor 700 (b), and motor 600 (c) at a rotational speed of 15000 rpm. Figure 19A This is a graph showing the magnetic flux density distribution of motor 200 in (a). Figure 19B This is a graph showing the magnetic flux density distribution of motor 700 in (b). Figure 19CThis is a graph showing the magnetic flux density distribution of motor 600 (c). Figure 20 This is a graph comparing the efficiency of motor 200 in (a), motor 700 in (b), and motor 600 in (c). Figure 21 This is a graph comparing the losses of motor 200 in (a), motor 700 in (b), and motor 600 in (c). Figure 22A This is a graph representing the eddy current loss of motor 200 in (a). Figure 22B The graph shows the eddy current loss of motor 700 in (b). Figure 22C This is a graph representing the eddy current loss of motor 600 in (c). Figure 23 This is a diagram showing the motor 800 according to the fourth embodiment of this disclosure. Detailed Implementation In the following detailed description, numerous specific details are presented for illustrative purposes and to provide a thorough understanding of the disclosed embodiments. However, it will be apparent that one or more embodiments can be implemented without these specific details. In other instances, well-known structures and apparatuses are shown schematically for the purpose of simplifying the drawings.

[0016] Hereinafter, embodiments of the present disclosure will be described with reference to the accompanying drawings. Furthermore, in the description of the embodiments, for ease of explanation, the description of components having the same reference numerals as those already described is omitted. Additionally, for ease of explanation, the dimensions of the components shown in these drawings may sometimes differ from the actual dimensions of the components.

[0017] <First Implementation Method> Figure 1 This is a diagram showing the motor 100 according to the first embodiment of this disclosure. Figure 1 The motor 100 shown is a 3-phase, 6-pole, 45-slot, distributed winding, IPMSM (Interior Permanent Magnet Synchronous Motor) with q=2.5 slots per pole per phase. The motor 100 is a rotating excitation type, comprising a stator 10 and a rotor 20 capable of rotating relative to the stator 10. The rotor 20 is wound relative to the stator 10... Figure 1 The rotation axis extends perpendicularly to the plane of the paper. Furthermore, the number of phases, poles, slots, and winding method of the motor disclosed herein are not limited to... Figure 1 Examples.

[0018] The stator 10 has a generally annular stator core 11. The stator core 11 has an annular rear yoke 11b and a plurality of teeth 11a disposed on the inner circumferential side of the rear yoke 11b. The teeth 11a are portions that protrude radially inward from the inner circumferential end of the rear yoke 11b. The plurality of teeth 11a are of approximately the same shape. A slot is provided between two adjacent teeth 11a.

[0019] Windings are arranged in slots. The windings are wound around each tooth 11a. Furthermore, the windings form stator coils 12. Each stator coil 12 is wound around the tooth 11a by distributed winding. The stator coils 12 are energized from the outside by alternating current.

[0020] The rotor 20 has a cylindrical rotor core 21. The rotor core 21 is formed by stacking multiple electromagnetic steel plates in the direction of the rotation axis. The inner circumferential hole of the rotor core 21 forms a shaft mounting hole 22. A drive shaft (not shown) is fixed in the shaft mounting hole 22. Rotation is transmitted to an object driven by the motor 100 via the drive shaft.

[0021] Multiple permanent magnets 23 are disposed on the rotor core 21 of the rotor 20. The permanent magnets 23 are embedded in slots disposed in the rotor core 21. The permanent magnets 23 are flat. The multiple permanent magnets 23 in the figure are roughly the same in size, material and composition.

[0022] Furthermore, in the illustrated example, multiple permanent magnets 23 are arranged at equal intervals on a circumference centered on the rotation axis O, with six poles spaced 60° apart from each other. This results in approximately the same magnetomotive force of each permanent magnet 23 relative to the stator coil 12. Additionally, rotor gaps 24 extending radially outward are provided at both ends of each permanent magnet 23. No components are present inside the rotor gaps 24. Air is present inside the rotor gaps 24.

[0023] However, in the motor 100 of this first embodiment, the stator core 11 includes an annular rear yoke 11b and a plurality of teeth 11a. The rear yoke 11b is made of a non-directional electromagnetic steel plate, which is a soft magnetic material. The teeth 11a are made of a non-linear soft magnetic material. The non-linear soft magnetic material used in this first embodiment is defined as a material having the following characteristics: it is not magnetized (the magnetic flux density remains low) until a certain magnetic field strength H is applied, but when the magnetic field strength H exceeds a certain value, the magnetic flux density increases sharply due to the increased relative permeability μr. Furthermore, in Figure 1 In the diagram, the shaded area represents the part composed of a nonlinear soft magnetic material (tooth 11a). Figure 1 In this text, the shaded lines are not general shaded lines representing cross-sections. The shaded lines on the stator core 11 indicate portions composed of nonlinear soft magnetic materials. Furthermore, the shaded lines on the rotor core 21 represent permanent magnets 23.

[0024] Here, use Figure 2 A detailed explanation of nonlinear soft magnetic materials is provided. Figure 2 It is a graph representing the BH curves of general soft magnetic materials and nonlinear soft magnetic materials. Figure 2 The horizontal axis represents the strength H of the magnetic field. Figure 2 The vertical axis represents the magnetic flux density B. Figure 2 In this study, we focus on the magnetic flux density B of general soft magnetic materials, such as non-directional electromagnetic steel plates, when the magnetic field strength H is near 0. At this point, as... Figure 2 As shown, when a magnetic field is applied, the magnetic flux density B increases sharply. Furthermore, as the strength of the magnetic field H increases, the magnetic flux density B converges to the saturation magnetic flux density Bs. That is, when a magnetic field is applied, the magnetic flux density B of a typical soft magnetic material increases immediately. On the other hand, as the strength of the magnetic field H increases, the rate of increase in magnetic flux density B slows down. Then, the magnetic flux density B converges to the saturation magnetic flux density Bs. In addition, materials with large relative permeability μr and high saturation magnetic flux density Bs are generally developed as soft magnetic materials. Here, relative permeability μr refers to... Figure 2 The slope of the BH curve. Furthermore, electromagnetic steel sheets, as a type of soft magnetic material, are generally required to be materials where the magnetic flux density B increases immediately when a magnetic field is applied. In the following description, for the purpose of contrasting with nonlinear soft magnetic materials, general soft magnetic materials that exhibit the characteristic of an immediate increase in magnetic flux density B even under weak magnetic fields are also referred to as linear soft magnetic materials.

[0025] In contrast, the magnetic flux density of the nonlinear soft magnetic material of interest to the inventors changes only slowly when the magnetic field strength H is near 0, even under the influence of a magnetic field. However, when the magnetic field strength H is a certain value Hk, the magnetic flux density B increases sharply. Thereafter, as the magnetic field strength H increases, the magnetic flux density B converges to the saturation magnetic flux density Bs. That is, the magnetic flux density B of the nonlinear soft magnetic material is difficult to increase during periods of weak magnetic fields below a certain value. On the other hand, when a strong magnetic field above a certain value is applied, the magnetic flux density B increases sharply. In other words, the nonlinear soft magnetic material has the following characteristic: even under the influence of a weak magnetic field strength H, magnetic flux is difficult to pass through, but under the influence of a strong magnetic field strength H, magnetic flux easily and rapidly passes through. Figure 2 In the BH curve, the strength of the magnetic field through which magnetic flux easily passes is represented as the rising magnetic field Hk. In the BH curve, the rising magnetic field Hk refers to the strength of the magnetic field when the magnetic flux density B of the nonlinear soft magnetic material becomes 25% of the saturation magnetic flux density Bs of the nonlinear soft magnetic material. Furthermore, in... Figure 1In the stator 10 of the motor 100 shown, a material with a rising magnetic field Hk of 6 kA / m is used as the nonlinear soft magnetic material. In addition, in the parts not made of nonlinear soft magnetic material, non-directional electromagnetic steel sheet with the designation 35H300 (manufactured by Nippon Steel Corporation) is used.

[0026] Return to Figure 1 In the motor 100 of this first embodiment, a non-magnetic portion 25 is provided in the rotor core 21. The non-magnetic portion 25 refers to a portion having a lower relative permeability than other portions. For example, the non-magnetic portion 25 can be formed by a hole provided in the illustrated rotor core 21 or by a cutout provided on the outer periphery of the rotor core 21. The non-magnetic portion 25 can also be an air portion. Alternatively, the non-magnetic portion 25 can be formed by a portion made of a non-metallic material with low relative permeability, such as resin. Furthermore, the non-magnetic portion 25 can also be made of a magnetic composite material with low iron loss.

[0027] At least a portion of the non-magnetic portion 25 is disposed in the portion of the rotor 20 opposite to the stator 10 of the permanent magnet 23 embedded in the rotor 20. The non-magnetic portion 25 is disposed at a position that interferes with the magnetic force acting between the permanent magnet 23 and the tooth 11a. Thus, the non-magnetic portion 25 functions in a manner that weakens the effect of the magnetic force of the permanent magnet 23 relative to the tooth 11a. The non-magnetic portions 25 are disposed in a manner corresponding to each permanent magnet 23. In the illustrated example, six non-magnetic portions 25 are disposed corresponding to six permanent magnets 23.

[0028] Figure 3 express Figure 1 The efficiency mapping diagram of the motor 100 according to this first embodiment is shown. Figure 3 In the diagram, the horizontal axis represents the rotational speed of the motor 100. The vertical axis represents the torque of the motor 100. Operating conditions with equal efficiency are connected by contour lines. To illustrate the characteristics of the motor 100 of this first embodiment, reference examples 1 and 2 will be described.

[0029] Figure 4 This is a diagram showing motor 200 as in Reference Example 1. (As shown...) Figure 4 As shown, motor 200 does not have a non-magnetic section 25. Furthermore, motor 200 is a synchronous motor with embedded magnets that does not have a section composed of a non-linear soft magnetic material. The number of poles and slots are... Figure 1 The motor 100 shown in the first embodiment is the same. Figure 5 express Figure 4 The efficiency mapping diagram of motor 200 is shown.

[0030] Figure 6 This is a diagram representing motor 300 in Reference Example 2. (As shown...) Figure 6As shown, the stator 10 of the motor 300 has a portion made of a nonlinear soft magnetic material. However, the rotor core 21 does not have a non-magnetic portion 25. Apart from this, the motor 300 is the same as the motor 200 of Reference Example 1. Figure 7 express Figure 6 The efficiency mapping diagram of motor 300 is shown.

[0031] First of all, Figure 5 and Figure 7 A comparison is made. Specifically, the motor 200 of Reference Example 1, which does not have a non-magnetic part 25 and does not have a non-linear soft magnetic material as the stator core 11, is compared with the motor 300 of Reference Example 2, which also does not have a non-magnetic part 25 but has a non-linear soft magnetic material as the stator core 11.

[0032] from Figure 5 as well as Figure 7 It can be seen that at a rotation speed of 3,000 min -1 In the following low-speed region, the torque of motor 200 in Reference Example 1 is 168 N·m. In contrast, the torque of motor 300 in Reference Example 2 is 163 N·m. That is, the torque of motor 300 in Reference Example 2 in the low-speed region is slightly lower than that of motor 200 in Reference Example 1.

[0033] At a rotational speed of 10,000 min -1 In the medium speed range, the torque of motor 200 in Reference Example 1 is 37.4 N·m. In contrast, the torque of motor 300 in Reference Example 2 is 42.5 N·m. That is, in the medium speed range, at the same rotational speed, the torque of motor 300 in Reference Example 2 is 13.6% higher than the torque of motor 200 in Reference Example 1.

[0034] Furthermore, the high-efficiency region of the motor 300 in Reference Example 2 is wider than that of the motor 200 in Reference Example 1. Specifically, in the motor 200 of Reference Example 1, the upper limit of the rotational speed at which 95% efficiency is achieved is less than 10,000 min. -1 In contrast, in the motor 300 of Reference Example 2, the upper limit of the rotational speed at which 95% efficiency is achieved is 12,000 min. -1 Left and right. That is, in the motor 300 of Reference Example 2, compared with the motor 200 of Reference Example 1, the efficiency is improved in the low torque and high speed region.

[0035] (The effect produced by nonlinear soft magnetic materials) When the motor 300 of Reference Example 2 is driven in the low-torque, high-speed region, the magnetic flux generated in the stator coil 12 is small. Therefore, the magnetic flux generated by the permanent magnet 23 of the rotor 20 is dominant. In this state, the strength of the magnetic field is less than the rising magnetic field Hk of the nonlinear soft magnetic material used in the teeth 11a. Therefore, the magnetic flux density of the teeth 11a is small. Therefore, even when the rotor 20 operates at high speed, the induced voltage of the stator coil 12 is small. As a result, copper losses in the stator coil 12 can be suppressed. Furthermore, when a magnetic field strength of a certain or greater does not act on the teeth 11a, its magnetic flux density does not increase. Therefore, the magnetic flux density of the teeth 11a located in a certain region that contributes to torque can be increased, and the magnetic flux density in other parts that do not contribute to torque can be suppressed to a low level. As a result, iron losses caused by the teeth 11a that do not contribute to torque can be suppressed. Therefore, overall efficiency is improved. That is, efficiency is improved in the low-torque, high-speed region.

[0036] Furthermore, when the motor is driven with high torque, the current carrying capacity of the stator coil 12 increases. In this state, the strength of the magnetic field acting on the tooth 11a is the sum of the magnetic flux of the permanent magnet 23 and the magnetic flux of the stator coil 12. Therefore, the strength of the acting magnetic field is greater than the rising magnetic field Hk of the nonlinear soft magnetic material. As a result, the magnetic flux density of the tooth 11a increases. Thus, in the motor 300 of Reference Example 2, high torque can be output in the medium speed region.

[0037] Furthermore, when high torque is desired, a high voltage is applied to the stator coil 12. In this state, a large magnetic field is applied to the stator coil 12. Therefore, regardless of whether the stator coil 12 is made of a linear soft magnetic material or a nonlinear soft magnetic material, the magnetic flux density of the stator coil 12 is the same as the saturation magnetic flux density Bs. Therefore, the maximum torque of the motor 300 in Reference Example 2 is the same as that of the motor 200 in Reference Example 1. Thus, by using a nonlinear soft magnetic material in at least a portion of the stator core 11, the efficiency of the motor can be improved.

[0038] Next, regarding Figure 3 and Figure 7 Comparison was made at a rotational speed of 3,000 min. -1 In the following low-speed region, the torque of the motor 300 in Reference Example 2 is 163 N·m. In contrast, the torque of the motor 100 in the first embodiment is 165 N·m. That is, the motor 100 of the first embodiment has a higher torque in the low-speed region compared to the motor 300 in Reference Example 2.

[0039] At a rotational speed of 10,000 min -1In the medium speed range, the torque of motor 300 in Reference Example 2 is 42.5 N·m. In contrast, the torque of motor 100 in the first embodiment is 42.9 N·m. That is, in the medium speed range, at the same rotational speed, the torque of motor 100 in the first embodiment is greater than the torque of motor 300 in Reference Example 2.

[0040] Furthermore, the high-efficiency region of the motor 100 in the first embodiment is wider than that of the motor 300 in Reference Example 2. Specifically, in the motor 300 of Reference Example 2, the upper limit of the rotational speed at which 95% efficiency is achieved is 12,000 min. -1 Around. In contrast, in the motor 100 of the first embodiment, the upper limit of the rotational speed at which 95% efficiency is achieved is 13,500 min. -1 The motor 100 of the first embodiment achieves high torque in the low-speed region and high efficiency in the high-speed region. Furthermore, the motor 100 of the first embodiment has a higher torque in the high-speed region than the motor 300 of Reference Example 2. This torque is also comparable to that of the motor 200 of Reference Example 1.

[0041] Next, use Figure 8 as well as Figure 9 The mechanism by which the motor 100 of this first embodiment achieves the above-mentioned effects will be explained. Figure 8 This is a graph showing the magnetic flux density distribution of the motor 200 in Reference Example 1. Figure 9 This is a graph showing the magnetic flux density distribution of the motor 100 according to the first embodiment. Figure 8 as well as Figure 9 All indicate that the rotor rotates at a speed of 15,000 min. -1 The diagram shows the magnetic flux density distribution when rotating counterclockwise. Figure 9 In the example shown, the non-magnetic portion 25 is disposed in the rotor 20 in a region further clockwise than the d-axis. Figures 8 to 10 In the diagram, the darker the color, the higher the magnetic flux density distribution.

[0042] like Figure 8 As shown, the magnetic flux density of the teeth 11a of the motor 200 in Reference Example 1 is 1T or more. In particular, the magnetic flux density of the two teeth 11a located near the counterclockwise end and the clockwise end of the permanent magnet 23 is increased.

[0043] In contrast, Figure 9 The magnetic flux density of the teeth 11a of the motor 100 in the first embodiment shown is different depending on the teeth 11a.

[0044] (The effect produced by the non-magnetic part 25) However, when tooth 11a generates torque, if the magnetic flux density of each tooth 11a at a certain moment is observed, it can be identified that there are teeth 11a that generate torque, teeth 11a with high magnetic flux density that do not contribute to torque generation, or teeth 11a that generate torque in the negative direction. Torque in the negative direction refers to the torque acting on rotor 20 in a way that decelerates rotor 20. Among these, teeth 11a that generate zero or negative torque become the cause of various performance degradations. These performance degradations include torque braking, torque pulsation, and losses.

[0045] Therefore, in the motor 100 of this first embodiment, at least a non-magnetic portion 25 is provided in the part of the rotor 20 where the permanent magnet 23 embedded in the rotor 20 and the stator 10 are opposite each other. Through this non-magnetic portion 25, the magnetic flux of the teeth 11a that generate negative torque is difficult to pass through. The function of this non-magnetic portion 25 will be explained below.

[0046] Here, we focus on a permanent magnet 23 and discuss the magnetic flux density of the eight teeth 11a located near the permanent magnet 23. For example... Figure 1 As shown, an imaginary line extending radially from near the center of the permanent magnet 23 is called the d-axis. Furthermore, an imaginary line extending radially between adjacent permanent magnets 23 is called the q-axis. The eight teeth 11a discussed here can also be considered as teeth 11a located between the two q-axis. For convenience, the tooth 11a located at the counterclockwise end of the eight teeth 11a is called the first tooth 11a1. The tooth 11a located at the clockwise end is called the eighth tooth 11a8.

[0047] The case where the first tooth 11a1 generates a magnetic force that attracts the permanent magnet 23 is examined. That is, the case where the resulting torque accelerates the rotor 20 is examined. However, unlike the first embodiment, in this case, the rotor 20 does not have a non-magnetic part 25. Figure 8 In the motor 200 of Reference Example 1 shown, the same level of magnetic flux density also acts on the eighth tooth 11a8. Therefore, the eighth tooth 11a8 attracts the permanent magnet 23. The magnetic force of the eighth tooth 11a8 attracting the permanent magnet 23 decelerates the rotor 20 rotating counterclockwise.

[0048] However, as Figure 1 as well as Figure 9 As shown, near the clockwise end of the rotor 20 of the motor 100 in this first embodiment, a non-magnetic portion 25 is provided to reduce the magnetic force acting on the stator 10 from the permanent magnet 23. That is, the non-magnetic portion 25 is provided in a way that makes it difficult for the magnetic flux of the eighth tooth 11a8, which generates a negative torque, to pass through. Therefore, the magnetic flux density in the eighth tooth 11a8 is difficult to increase.

[0049] Thus, in the motor 100 according to this first embodiment, the magnetic force generated between the permanent magnet 23 and the first tooth 11a1 that accelerates the rotor 20 in the counterclockwise direction remains unchanged. At the same time, the magnetic force generated between the permanent magnet 23 and the eighth tooth 11a8 that decelerates the rotor 20 in the counterclockwise direction is reduced. Therefore, the motor 100 of this first embodiment can output high torque even at the same speed compared to the motor 200 of Reference Example 1 or the motor 300 of Reference Example 2.

[0050] Furthermore, only the effective component of the magnetic flux generated by the excitation magnetomotive force linked to the winding, which is in the positive direction, plays a role. On the other hand, other magnetic flux densities are suppressed. Therefore, even at high-speed rotation, it is difficult to generate back electromotive force. That is, voltage saturation caused by high-speed driving is improved. As a result, high torque can be output. In addition, in the motor 100 of this first embodiment, it is not necessary to use permanent magnets with particularly weak magnetic forces. Therefore, even at low-speed rotation, high torque can be output.

[0051] and then, Figure 9 The stator 10 of the motor 100 shown in this first embodiment is generally consistent with... Figure 8 Compared to the stator 10 of the motor 200 shown in Reference Example 1, there are more regions with low magnetic flux density. Therefore, iron losses are less likely to occur. Furthermore, since there are more regions with low magnetic flux density, the amount of magnetic flux linked to the stator coils 12 is reduced. Therefore, back electromotive force is suppressed. The effect of suppressing this back electromotive force is more significant when the motor 100 rotates at high speed. Thus, the motor 100 according to this first embodiment can provide a motor that can suppress back electromotive force at high speed without reducing torque at low speeds.

[0052] Furthermore, in this first embodiment, at least a portion of the teeth 11a are composed of a nonlinear soft magnetic material. The magnetic flux density of this nonlinear soft magnetic material will not increase as long as a strong magnetic field is not applied. Therefore, the magnetic flux density of the eighth tooth 11a8 is even less likely to increase.

[0053] In addition, refer to Figure 1 as well as Figure 9 The example described is a motor comprising teeth 11a made of a nonlinear soft magnetic material and an opening provided near the clockwise end of the permanent magnet 23. However, this embodiment is not limited to these examples. If the portion made of the nonlinear soft magnetic material is provided in at least a portion of the stator 10, the magnetic flux density will not increase as long as a certain or higher magnetic field strength is not applied. Therefore, the magnetic flux density in portions that do not contribute to torque can be suppressed to a low level. As a result, iron loss caused by teeth 11a that do not contribute to torque generation can be suppressed. As a result, overall efficiency is improved. That is, by providing a nonlinear soft magnetic material in at least a portion of the stator 10, the efficiency of the motor 100 can be improved.

[0054] Alternatively, the non-magnetic portion 25 can also be configured to obstruct the magnetic flux along the d-axis relative to the permanent magnet 23. Furthermore, the non-magnetic portion 25 is preferably configured as follows: Figure 1 As shown, the rotor 23 is arranged asymmetrically with respect to the d-axis. In the illustrated example, a non-magnetic portion 25 is provided on the rotor 20 in the counter-clockwise direction with respect to the d-axis. On the other hand, a non-magnetic portion 25 is provided on the rotor 20 in the clockwise direction with respect to the d-axis. As a result, when the rotor 20 rotates counter-clockwise, characteristics such as increased torque and increased efficiency are improved.

[0055] in addition, Figure 10 This is a graph showing the magnetic flux density distribution of the motor 300 in Reference Example 2. (As shown...) Figure 10 As shown, at least a portion of the stator 10 is composed of a nonlinear soft magnetic material. However, the rotor 20 does not have a nonmagnetic portion 25. In the motor 300 of this Reference Example 2, the overall magnetic flux density of the stator 10 is reduced, while the magnetic flux density near the first tooth 11a1 is increased. However, compared with... Figure 9 Compared to the motor 100 of the first embodiment shown, the reduction effect of magnetic flux density of the eighth tooth 11a8 is insufficient. Therefore, it can be confirmed that the reduction effect of magnetic flux density of the eighth tooth 11a8 resulting from providing the non-magnetic part 25 to the rotor 20 is effective.

[0056] <Variation Example> Furthermore, the aforementioned motor 100 exhibits improved performance in a specific rotational direction. Therefore, it can also be configured as follows: Figure 11 The motor 400 shown. In the modified motor 400 of this embodiment, the non-magnetic portions 25 of the multiple stacked iron chips (stacked iron chips) constituting the rotor 20 are staggered in the stacking direction. Figure 11 This is a diagram showing the rotor 20 of the motor 400 in a modified example of this embodiment.

[0057] Figure 11 The modified motor 400 shown includes a first layer of stacked iron chips 26 and a second layer of stacked iron chips 27. In the first layer of stacked iron chips 26, with Figure 1 Similar to the example shown, the non-magnetic portion 25 is not provided in the clockwise direction from the d-axis. On the other hand, the non-magnetic portion 25 is provided in the counterclockwise direction from the d-axis. In the second layer of stacked iron chips 27, unlike the first layer of stacked iron chips 26, the non-magnetic portion 25 is provided in the clockwise direction from the d-axis. On the other hand, the non-magnetic portion 25 is not provided in the counterclockwise direction from the d-axis. These first layer of stacked iron chips 26 and second layer of stacked iron chips 27 are stacked in the direction of the rotation axis of the motor 400.

[0058] With this structure, the non-magnetic portions 25 of adjacent stacked iron chips 26 and 27 in the direction of rotation axis (stack direction) are staggered. According to this motor 400, regardless of the direction of rotation, the torque is not reduced at low speeds, and the back electromotive force is suppressed at high speeds.

[0059] In addition, such as Figure 11 As shown, preferably, the stacked iron chips 26 and 27 are stacked such that not only are the positions of the non-magnetic portions 25 of adjacent stacked iron chips 26 and 27 staggered, but the positions of the non-magnetic portions 25 of adjacent stacked iron chips 26 and 27 are also symmetrical with respect to the d-axis.

[0060] <Second Implementation Method> Furthermore, in the motor 100 described as an example of the first embodiment, the rotor 20 includes a non-magnetic portion 25, and at least a portion of the stator 10 is made of a non-linear soft magnetic material. However, as in the motor 500 of the second embodiment described below, the rotor 20 may include a non-magnetic portion 25, while the stator 10 may not be made of a non-linear soft magnetic material.

[0061] Figure 12 This is a diagram illustrating the motor 500 according to the second embodiment of this disclosure. (See diagram) Figure 12 As shown, in the motor 500, at least a portion of the permanent magnet 23 embedded in the rotor 20 and the portion opposite to the stator 10 is provided with a non-magnetic part 25. Furthermore, the stator 10 is entirely constructed of a non-directional electromagnetic steel plate that is not a non-linear soft magnetic material.

[0062] Figure 13 This is the efficiency mapping diagram for Motor 500. (Example) Figure 13 As shown, the maximum torque in the low-speed region is 168 N·m. Thus, the torque does not decrease during low-speed rotation. Furthermore, the maximum torque in the high-speed region of the motor 500 of the second embodiment is also comparable to that of the motor 200 of Reference Example 1.

[0063] Furthermore, in the motor 500 of the second embodiment, the upper limit of the rotational speed at which 95% efficiency is achieved is 11,000 min. -1 Approximately. This upper limit is greater than the upper limit of the rotational speed at which 95% efficiency is achieved in the motor 200 of Reference Example 1, which is 95,000 min. -1 The second embodiment of the motor 500 also achieves high torque in the low-speed region and high efficiency in the high-speed region. The rotational speed of the second embodiment of the motor 500 is 10,000 min. -1 The maximum torque at that time was 41 N·m. This value is similar to that of the motor 200 in Reference Example 1 at a rotational speed of 10,000 min. -1The maximum torque at low speed is 37.4 N·m, which is 9.6% higher than before. Thus, in the motor 500 of the second embodiment, it can also be confirmed that the back electromotive force at high speed is suppressed without reducing the torque at low speed.

[0064] Figure 14 This is a graph showing the magnetic flux density distribution of the motor 500 according to the second embodiment. Figure 14 In this context, the darker the color, the higher the magnetic flux density distribution. From... Figure 8 The motor 200 in Reference Example 1 and Figure 14 A comparison with the motor 500 of the second embodiment shows that, in the motor 500 of the second embodiment, the magnetic flux density near the first tooth 11a1 is maintained. At the same time, the magnetic flux density near the eighth tooth 11a8 is reduced. Therefore, in the motor 500 of the second embodiment, the back electromotive force during high-speed rotation can be suppressed without reducing the torque during low-speed rotation.

[0065] <Third Implementation Method> However, in the first and second embodiments described above, the elliptical non-magnetic portion 25 having a major axis in the d-axis direction was described, but this disclosure is not limited thereto. Figure 15 This diagram illustrates a motor 600 according to a third embodiment of this disclosure. At least a portion of the stator 10 of the motor 600 of the third embodiment is made of a nonlinear soft magnetic material. (As shown...) Figure 15 As shown, in this embodiment, a non-magnetic portion 25 extending along the q-axis direction is provided. The illustrated non-magnetic portion 25 extends from the right side (clockwise end) of the permanent magnet 23 to a near-forward slit on the surface of the rotor 20, and from the left side (counter-clockwise end) of the permanent magnet 23 to a near-forward slit on the surface of the rotor 20. In the following description, this non-magnetic portion 25 extending along the q-axis direction will be specifically referred to as the q-axis magnetic flux barrier 601.

[0066] Figure 16A and Figure 16B This diagram illustrates the function of the q-axis flux barrier 601. Figure 16A This is an enlarged view of the motor 200 in Reference Example 1 without the q-axis flux barrier 601. Figure 16B This is an enlarged view of the motor 600 of the third embodiment, which is equipped with a q-axis magnetic flux barrier 601. Figure 16A and Figure 16B In this case, it is assumed that rotor 20 rotates in a counterclockwise direction.

[0067] (Increased torque) like Figure 16AAs shown, focus is placed on the magnetic flux passing through the first tooth 611 and the second tooth 612, which are adjacent in the circumferential direction. Furthermore, it is explicitly stated that the first tooth 611 mentioned here is unrelated to the first tooth 11a1 described above. The magnetic flux from the first tooth 611 through the rotor 20 and via the second tooth 612 imparts a positive (counterclockwise) torque and a negative torque to the rotor 20. Specifically, in the illustrated example, the magnetic flux from the first tooth 611 through the rotor 20 imparts a positive torque to the rotor 20, but the magnetic flux from the rotor 20 through the second tooth 612 imparts a negative torque to the rotor 20.

[0068] Here, as Figure 16B As shown, when the q-axis flux barrier 601 is provided, the magnetic flux flowing between the first tooth 611 and the second tooth 612 and the rotor 20 can be limited. That is, as Figure 16A As shown, if the q-axis flux barrier 601 is not set, the flux entering the rotor 20 from the first tooth 611 is equal to the flux exiting the rotor 20 to the second tooth 612, but if... Figure 16B As shown, when the q-axis flux barrier 601 is provided, the magnetic flux entering the rotor 20 from the first tooth 611 is different from the magnetic flux exiting the rotor 20 to the second tooth 612. Thus, by controlling the magnetic flux through the q-axis flux barrier 601, the torque in the positive direction can be increased. Furthermore, by adjusting the position and size of the q-axis flux barrier 601, the effect of increasing the torque in the positive direction can be enhanced.

[0069] (Increase in maximum torque) Figure 17 This graph compares the maximum torque of three types of motors: 200, 600, and 700. Figure 17 In the text, (a) represents the embedded magnet synchronous motor 200 of Reference Example 1, which does not have a q-axis magnetic flux barrier 601 and does not have a portion made of a nonlinear soft magnetic material; (b) represents the embedded magnet synchronous motor 700, which has a q-axis magnetic flux barrier 601 but does not have a portion made of a nonlinear soft magnetic material; and (c) represents the motor 600 of the third embodiment. Figure 17 The maximum torque that motors 200, 600, and 700 (a) to (c) can produce under the conditions of phase voltage below 600V and phase current below 300A is indicated.

[0070] like Figure 17 As shown, compared to the motor 200 in (a), the maximum torque of motor 700 in (b) is increased in the low-speed rotation region of 1000 rpm. The motor 600 in the third embodiment of (c) performs the same as that in (b) in the low-speed rotation region, and furthermore, in the high-speed rotation region of 20000 rpm and above, the maximum torque is increased compared to that of motor 700 in (b).

[0071] (Improved torque distribution) Figure 18 This is a diagram showing the torque distribution on the surface of the rotor 20 of motors 200 (a), 700 (b), and 600 (c) at a rotational speed of 15000 rpm. Below, Figures 18-21 Motor 200 in (a), motor 700 in (b), and motor 600 in (c) are... Figure 17 The motors 200 in (a), 700 in (b), and 600 in (c) have the same meaning.

[0072] Regarding the torque generated at the tooth tip, as described above, the positive torque is increased by the q-axis flux barrier 601. Therefore, at an electrical angle of 45 degrees, etc., the positive torque of motor 700 in (b) is increased compared to motor 200 in (a). Furthermore, at an electrical angle of 60 degrees, etc., the positive torque of motor 600 in (c) is further increased compared to motor 700 in (b). This is because the increased positive torque by the q-axis flux barrier 601 is further increased due to the more concentrated magnetic flux caused by the nonlinear soft magnetic material. In addition, from Figure 18 It can be confirmed that, at an electrical angle of 115 degrees, the negative torque of motor 700 in (b) and motor 600 in (c) is reduced compared to motor 200 in (a).

[0073] (Improvement of magnetic flux density) Figure 19A This is a graph showing the magnetic flux density distribution of motor 200 in (a). Figure 19B This is a graph showing the magnetic flux density distribution of motor 700 in (b). Figure 19C This is a graph showing the magnetic flux density distribution of motor 600 (c). Figures 19A to 19C In the diagram, the darker the color, the higher the magnetic flux density distribution. right Figure 19A and Figure 19B A comparison shows that by setting the q-axis flux barrier 601, the flux can be concentrated on the first tooth 611 (the tooth that contributes to positive torque) to which the flux is desired to pass, and the flux flowing to the second tooth 612 (the tooth that contributes to negative torque) to which the flux is not desired to pass can be reduced. Figure 19B and Figure 19C Comparison shows that by using nonlinear soft magnetic materials, the magnetic flux density of the second tooth 612, which is not intended to carry magnetic flux, can be further reduced. This improves the efficiency of the motor 600.

[0074] Figure 20 This graph compares the efficiencies of motor 200 in (a), motor 700 in (b), and motor 600 in (c). Figure 20 As shown, motor 600 in (c) achieves higher efficiency in the high-speed rotation region compared to motor 200 in (a) and motor 700 in (b).

[0075] Figure 21 This is a graph comparing the losses of motor 200 in (a), motor 700 in (b), and motor 600 in (c). Figure 21 As shown, motor 700 in (b) and motor 600 in (c) concentrate the magnetic flux to the first tooth 611 (refer to) where the magnetic flux is desired to pass. Figure 16B Therefore, compared with motor 200 in (a), the loss of stator teeth is small.

[0076] Furthermore, as described later, the demagnetization at the end of the permanent magnet 23 is improved by the q-axis flux barrier 601; therefore, the eddy current losses of motor 700 in (b) and motor 600 in (c) are smaller than those of motor 200 in (a). Additionally, in Figure 21 In (a), motor 200 cannot operate at 15,000 to 30,000 rpm, so the loss is assumed to be 0. Similarly, in (b), motor 700 cannot operate at 30,000 rpm, so the loss is assumed to be 0.

[0077] Return to Figure 16A and Figure 16B .exist Figure 16A and Figure 16B In the example shown, non-magnetic portions 25 extending circumferentially are provided at both ends of the permanent magnet 23. These non-magnetic portions 25 extending circumferentially at both ends of the permanent magnet 23 are referred to as the first magnetic flux barrier 602.

[0078] like Figure 16A As shown, if the q-axis flux barrier 601 is not provided, the flux passing through the first flux barrier 602 of the rotor 20 enters the permanent magnet 23 from the radially inner side. Then, the flux passing through the permanent magnet 23 travels toward the teeth 611, 612. In particular, the flux also passes through the end of the permanent magnet 23.

[0079] However, as Figure 16BAs shown, when the q-axis flux barrier 601 is set, the magnetic flux does not enter the region between the first flux barrier 602 and the q-axis flux barrier 601. Therefore, the flux passes through the central region of the permanent magnet 23 and bypasses the end of the permanent magnet 23. Thus, the demagnetization at the end of the permanent magnet 23 is improved. For example, when the magnetic flux density at the end of the permanent magnet 23 of the motor 200 in (a) is 2 [T], under the same conditions, it is reduced to about 1.8 [T] in the motor 700 in (b) and to about 1.7 [T] in the motor 600 in (c). Similarly, when the magnitude of the magnetic field at the end of the permanent magnet 23 of the motor 200 in (a) is 500 [kA / m], under the same conditions, it is improved to about 450 [kA / m] in the motor 700 in (b) and to about 420 [kA / m] in the motor 600 in (c).

[0080] Figure 22A This is a graph representing the eddy current loss of motor 200 in (a). Figure 22B The graph shows the eddy current loss of motor 700 in (b). Figure 22C This is a graph representing the eddy current losses of motor 600 (c). Figure 22A and Figure 22B A comparison shows that at the end of the permanent magnet 23, the linkage flux is reduced and eddy current losses are decreased through the q-axis flux barrier 601. Figure 22B and Figure 22C The comparison shows that at the end of the permanent magnet 23, the eddy current loss is further reduced by the nonlinear soft magnetic material and the q-axis magnetic flux barrier 601, which reduces the linkage magnetic flux.

[0081] Thus, motors 700 and 600 with q-axis flux barrier 601 have a large maximum torque over a wide rotational speed range. Figure 17 High efficiency Figure 20 ), and thus the losses are also small ( Figure 21 Furthermore, these characteristics, such as maximum torque, efficiency, and loss, are further improved by the fact that at least a portion of the stator 10 is made of a nonlinear soft magnetic material.

[0082] Figure 23 This is a diagram illustrating the motor 800 according to the fourth embodiment of this disclosure. (See diagram) Figure 23As shown, a d-axis flux barrier 801 extending along the d-axis and a q-axis flux barrier 802 extending along the q-axis can also be provided near both ends of the permanent magnet 23 as a non-magnetic part 25. The d-axis flux barrier 801 and the q-axis flux barrier 802 can also be provided continuously. In the illustrated example, q-axis flux barriers 802 are provided at both ends of the permanent magnet 23, and the d-axis flux barriers 801 extend in directions away from each of the q-axis flux barriers 802. With this structure, as described above, the characteristics of various motors are also improved. For example, a motor 800 having both a d-axis flux barrier 801 and a q-axis flux barrier 802 provides higher maximum torque and efficiency over a wider rotational speed range compared to a motor with only a d-axis flux barrier 801 or only a q-axis flux barrier 802. The motor 800 of the fourth embodiment of this disclosure may also have at least a portion of its stator 10 made of a nonlinear soft magnetic material.

[0083] The above describes this embodiment. However, it should be understood that the technical scope of this embodiment should not be interpreted limitedly by the description of this embodiment. The described embodiment is merely an example. It should be understood by those skilled in the art that various modifications can be made to the described embodiment within the scope disclosed in the claims. The technical scope of this embodiment should be determined based on the scope disclosed in the claims and its equivalents. The detailed description has been given for illustrative and explanatory purposes. Many variations and modifications are possible in accordance with the teachings above. The detailed description is not without omissions or intended to limit the subject matter described herein. Although the subject matter has been described in words with particular structural features and / or methodological processes, it should be understood that the subject matter defined in the claims is not necessarily limited to the specific features or processes described. Rather, the specific features and processes described are illustrated as examples of implementing the claims.

Claims

1. A motor, wherein, The motor includes: a stator comprising a stator core having teeth and windings wound around the teeth; and a rotor comprising permanent magnets. At least a portion of the permanent magnet embedded in the rotor that is opposite the stator is provided with a non-magnetic part.

2. The motor according to claim 1, wherein, At least a portion of the stator is made of a nonlinear soft magnetic material.

3. The motor according to claim 1, wherein, The non-magnetic portion is configured to impede the magnetic flux along the d-axis relative to the permanent magnet.

4. The motor according to claim 1, wherein, The non-magnetic portion is arranged asymmetrically with respect to the d-axis.

5. The motor according to claim 1, wherein, The rotor is composed of multiple iron chips. The plurality of iron chips are stacked in such a way that the positions of the non-magnetic portions of adjacent iron chips are staggered.

6. The motor according to claim 1, wherein, The rotor is composed of multiple iron chips. The plurality of iron chips are stacked in a manner in which the positions of the non-magnetic portions of adjacent iron chips are symmetrical with respect to the d-axis.

7. The motor according to claim 1, wherein, The non-magnetic portion is configured to extend along the q-axis direction.

8. The motor according to claim 2, wherein, The non-magnetic portion is configured to extend along the q-axis direction.

9. The motor according to claim 1, wherein, The non-magnetic portion has a d-axis magnetic flux barrier extending along the d-axis direction and a q-axis magnetic flux barrier extending along the q-axis direction.

10. The motor according to claim 2, wherein, The non-magnetic portion has a d-axis magnetic flux barrier extending along the d-axis direction and a q-axis magnetic flux barrier extending along the q-axis direction.

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