CN111052546B

CN111052546B - Rotor of rotating electric machine

Info

Publication number: CN111052546B
Application number: CN201780092221.8A
Authority: CN
Inventors: 室田浩平; 池见健; 仲田彻
Original assignee: Nissan Motor Co Ltd
Current assignee: Nissan Motor Co Ltd
Priority date: 2017-06-19
Filing date: 2017-06-19
Publication date: 2022-06-24
Anticipated expiration: 2037-06-19
Also published as: JPWO2018235145A1; JP6821022B2; WO2018235145A1; CN111052546A

Abstract

A rotor of a rotating electric machine according to an aspect of the present invention is a rotor in which a plurality of single magnetic poles are arranged in a circumferential direction, the single magnetic poles being configured by: a pair of 1 st permanent magnets arranged in a V-shape open in the outer circumferential direction; and a 2 nd permanent magnet disposed in the V-shaped open portion, the rotor of the rotating electrical machine including: a 1 st gap provided continuously with the magnet insertion hole at an end portion on a q-axis side electrically orthogonal to a d-axis constituted by a single magnetic pole in the magnet insertion hole into which the 1 st permanent magnet is inserted; a 2 nd gap provided to be continuous with the magnet insertion hole at both end portions of the magnet insertion hole into which the 2 nd permanent magnet is inserted; and a groove formed in the outer periphery of the rotor in the axial direction of the rotor. When a straight line drawn out to the outer periphery through the rotation center of the rotor and the d-axis side end of the 1 st gap is a straight line a, and a straight line drawn out to the outer periphery through the rotation center and the q-axis side end of the 2 nd gap is a straight line B, the q-axis side end of the groove is located on the straight line a, and the d-axis side end of the groove is located on the q-axis side of the straight line B.

Description

Rotor of rotating electric machine

Technical Field

The present invention relates to a rotor of a rotating electric machine.

Background

As a motor for driving an electric vehicle such as an electric vehicle or a hybrid vehicle, an embedded Magnet type Permanent Magnet motor (hereinafter, referred to as an IPM motor as appropriate) in which a rotor core is embedded with a Permanent Magnet is known.

The IPM motor has a problem that iron loss is generated by magnetic flux of the permanent magnet, and the efficiency in a high-speed rotation region is lowered due to the iron loss. In addition, in order to suppress vibration and noise of the motor, it is also required to reduce torque ripple.

From the viewpoint of ensuring the durability of the inverter components, it is also necessary to prevent the peak value of the induced voltage from exceeding the withstand voltage of the inverter system. When the induced voltage is synthesized from a main component favorable to torque and a higher harmonic component unfavorable to torque, if only the induced voltage is reduced without exceeding the withstand voltage of the inverter system, the main component may be reduced to cause a decrease in torque. Therefore, in order to prevent the torque from decreasing, it is necessary to decrease only the harmonic component so that the peak value of the induced voltage is decreased.

In order to meet the above requirements, JP5516739B proposes a rotor structure in which a single magnetic pole is formed by a pair of permanent magnets arranged in a V shape that opens in the outer circumferential direction and a total of 3 permanent magnets arranged in the open portion of the V shape, and a groove is formed in the outer circumference. According to the rotor structure proposed herein, it is possible to provide a motor in which the iron loss is reduced and the cogging torque and the induced voltage are reduced by forming the slots.

Disclosure of Invention

However, with the slot disclosed in JP5516739B, the inventors of the present invention have found that there is a problem in that, since the center position of the outer periphery of the rotor is nevertheless specified, the iron loss reduction effect cannot be sufficiently obtained due to the circumferential width of the permanent magnet disposed at the outermost periphery, and the motor efficiency cannot be improved.

Therefore, an object of the present invention is to provide a rotor in which a circumferential width of a groove formed in an outer periphery of the rotor is defined in consideration of a positional relationship with a permanent magnet disposed in an outermost periphery, thereby sufficiently obtaining an iron loss reduction effect.

A rotor of a rotating electric machine according to an aspect of the present invention has a plurality of single magnetic poles arranged in a circumferential direction, and the single magnetic poles are configured by: a pair of 1 st permanent magnets arranged in a V-shape open in the outer circumferential direction; and a 2 nd permanent magnet disposed in the V-shaped open portion, having: a 1 st gap provided continuously with the magnet insertion hole in which the 1 st permanent magnet is inserted, at an end portion on a q-axis side electrically orthogonal to a d-axis constituted by a single magnetic pole; a 2 nd gap provided continuously with the magnet insertion hole at both end portions of the magnet insertion hole into which the 2 nd permanent magnet is inserted; and a groove formed in the outer periphery of the rotor in the axial direction of the rotor. When a straight line drawn to the outer periphery through the rotation center of the rotor and the d-axis side end of the 1 st gap is defined as a straight line a, and a straight line drawn to the outer periphery through the rotation center and the q-axis side end of the 2 nd gap is defined as a straight line B, the q-axis side end of the groove is located on the straight line a, and the d-axis side end of the groove is located on the q-axis side of the straight line B.

Embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

Drawings

Fig. 1 is a diagram for explaining a rotor structure according to an embodiment.

Fig. 2 is a diagram showing an analysis result of analyzing the iron loss reduction rate at the position corresponding to the starting point of the groove.

Fig. 3 is a diagram showing an analysis result of analyzing a change in stress of the bridge portion at a position corresponding to a starting point of the groove.

Fig. 4 is a diagram for explaining an analysis result of analyzing the magnetic flux density of the stator based on the outer peripheral shape of the rotor.

Fig. 5 is a diagram showing analysis results obtained by analyzing the motor loss ratios of the conventional example and the embodiment.

Fig. 6 is a diagram for explaining a starting point of a groove defined from the viewpoint of improving torque performance.

Fig. 7 is a graph showing the analysis result of analyzing the change in the 1 st-order component of the induced voltage based on the position of the starting point of the groove.

Fig. 8 is a diagram for explaining a position of a starting point of a slot which facilitates reduction of the cogging torque.

Fig. 9 is a diagram showing an analysis result of analyzing a change in cogging torque based on a position of a starting point of a slot.

Fig. 10 is a graph showing the analysis results of the change in the cogging torque and the 1 st-order component of the induced voltage based on the position of the starting point of the slot.

Fig. 11 is a diagram for explaining the depth d of the groove.

Fig. 12 is a diagram showing the analysis result of analyzing the iron loss reduction rate based on the depth d of the groove.

Fig. 13 is a diagram for explaining a groove of modification 1.

Fig. 14 is a diagram for explaining a groove of modification 2.

Fig. 15 is a diagram for explaining a groove of modification 3.

Fig. 16 is a diagram for explaining a groove of modification 4.

Fig. 17 is a diagram for explaining another modification.

Fig. 18 is a diagram showing an analysis result obtained by analyzing the loss ratio of the conventional example with respect to the reference example.

Detailed Description

Implementation scheme

Fig. 1 is a diagram for explaining a rotor to which an embodiment of the present invention is applied. This figure shows a configuration diagram of a rotor (rotor)6 of a rotating electrical machine constituting an electric motor or a generator, as viewed from a cross section perpendicular to an axial direction, and is a part (one pole) of the entire configuration. The rotating electrical machine according to the present embodiment is a so-called ipm (interior Permanent magnet) type rotating electrical machine in which Permanent magnets are embedded in a rotor 6, and includes a rotor having a plurality of single magnetic poles each constituted by a Permanent magnet group 30, and the Permanent magnet group 30 is constituted by 3 Permanent magnets in total of a pair of Permanent magnets 2 and a pair of Permanent magnets 3.

Here, an example of a rotor having an 8-pole structure is given, and the number of poles is not limited to this. It is assumed that the various analysis data described below are analyzed by applying the present invention to a rotating electrical machine including: a rotor 6 of 8-pole configuration; and a stator (not shown) having a slot number of 48, and around which the stator winding is wound in a distributed winding manner.

The rotor core (rotor core)1 is formed in a cylindrical shape by a so-called laminated electromagnetic steel plate structure, and is formed by laminating members formed by punching an electromagnetic steel plate having a thickness of several hundred μm into a circular ring shape in the axial direction. Further, the rotor core 1 includes: a magnet insertion hole 40 (hereinafter, also simply referred to as a magnet hole 40) for embedding the permanent magnet 2; and magnet insertion holes 50 (hereinafter also simply referred to as magnet holes 50) for embedding the permanent magnets 3, and gaps 4 (1 st gap) are formed continuously with the magnet holes at both circumferential ends of the magnet hole 40, and gaps 5 (2 nd gap) are formed continuously with the magnet holes at both circumferential ends of the magnet hole 50.

The

magnet holes

40 and 50 are holes formed by laminating single plates of electromagnetic steel plates in the axial direction, each of which has a space in which two permanent magnets 2 and one permanent magnet 3 are embedded.

The magnet hole 40 is formed in a so-called V shape in which a portion that is a central portion in the circumferential direction and is located closest to the rotation center side is located on the d axis, and both end portions in the circumferential direction are separated from the d axis and are close to the q axis and are close to the rotor outer periphery.

The magnet holes 50 are formed linearly along the circumferential direction of the rotor core 1 at the portions where the V-shaped magnet holes 40 are opened.

The permanent magnet group 30 is embedded in the magnet holes 40 and the

magnet holes

50, and 1 pair of permanent magnets 2 are embedded in one magnet hole 40 and one permanent magnet 3 is embedded in one magnet hole 50.

As shown in the drawing, since the magnet hole 40 has a shape that is line-symmetrical with respect to the d-axis, the pair of permanent magnets 2 are also arranged in a V-shape that is line-symmetrical with respect to the d-axis and opens in the outer circumferential direction. Further, an approximately triangular shape is formed by: 1 pair of permanent magnets 2 disposed in the magnet holes 40; and permanent magnets 3 arranged in the circumferential direction at the opened portions of the V-shape. A single magnetic pole formed by such a permanent magnet group 30 arranged in an approximately triangular shape is formed at every constant mechanical angle of the rotor 6. Since the rotor 6 of the present embodiment has an 8-pole structure, permanent magnet groups 30 arranged in a substantially triangular shape are formed at mechanical angles of 45 degrees. Shown in fig. 1 is one pole thereof.

The permanent magnet group 30 is fixed in a state of being inserted into the corresponding portion of each of the

magnet holes

40, 50 of the rotor core 1. The single magnetic poles of the permanent magnet groups 30 are arranged in the circumferential direction of the rotor 6 such that the magnetic poles of the permanent magnet groups 30 are spaced apart from each other at equal intervals and such that the polarities of the adjacent magnetic poles are different from each other. The direction of the magnetic flux formed by the permanent magnet group 30 is the d-axis (magnetic pole center), and the direction electromagnetically orthogonal to the d-axis is the q-axis.

The two permanent magnets 2 are formed smaller than the magnet hole 40, and when the pair of permanent magnets 2 are embedded in the magnet hole 40, a gap 4, which is a space portion continuous with the magnet hole 40, is formed on the q-axis side of the magnet hole 40 and on the outer peripheral side of the rotor, in other words, on the outer peripheral side of the permanent magnets 2.

Similarly, the permanent magnet 3 is formed to have a smaller width in the longitudinal direction (circumferential direction) than the magnet hole 50, and the gap 5, which is a space portion continuous with the magnet hole 50, is formed at both end portions in the circumferential direction of the magnet hole 50, in other words, at a portion on the q-axis side of the permanent magnet 3. The magnetic permeability of the above-described space portion is lower than that of the electromagnetic steel sheet, that is, the magnetic resistance is large. Therefore, the

gaps

4 and 5 function as magnetic shielding walls (magnetic flux barriers) through which magnetic flux (magnetic flux) hardly passes in the magnetic circuit of the rotor 6 formed by the permanent magnet group 30.

Further, the outer periphery of the rotor core 1 of the present embodiment faces the rotation center side of the rotor core 1, and a groove 10 is formed along the axial direction of the rotor core 1. Further, the slots 10 are formed in the outer periphery of the rotor core 1 in a region from the end of the gap 4 on the d-axis side to the end of the gap 5 on the q-axis side.

Referring to fig. 1, when a tangent line drawn from the rotation center of rotor core 1 to the outer periphery of rotor core 1 through the d-axis-side tip of gap 4 is defined as tangent line a, and a tangent line drawn from the rotation center of rotor core 1 to the outer periphery of rotor core 1 through the q-axis-side tip of gap 5 is defined as tangent line B, the d-axis-side end (start point) and the q-axis-side end (end point) of slot 10 in the circumferential width direction are formed in regions between tangent line a and tangent line B. The starting point and the ending point of the predetermined groove 10 will be described in detail later.

The bridge portion 7 is a region between the gap 5 and the outer periphery of the rotor core 1, and is the thinnest portion in the surface direction of the rotor core 1.

Here, before the groove 10 is explained in detail, a current rotor structure, characteristics of the structure, and problems will be explained.

JP5516739B (conventional example) proposes a rotor structure in which a total of 3 permanent magnets are arranged in a substantially triangular shape to form a single magnetic pole, and a slot is formed in the outer periphery of a rotor core. The above document discloses that the iron loss reduction effect can be achieved by setting the center position of the groove. More specifically, the groove center position of the groove is formed in a range of 1/4 cycles in the d-axis direction and 1/8 cycles in the q-axis direction with reference to a scale point in a region between the outermost permanent magnet and the q-axis among a plurality of scale points marked at electrical angular intervals of 1 cycle of the harmonic component of the torque ripple. According to the rotor structure, the motor can be provided, wherein the iron loss can be reduced, and the cogging torque and the induced voltage can be reduced.

However, the inventors of the present application have found that, depending on the circumferential width of the permanent magnet on the outermost periphery side among the 3 permanent magnets formed in the approximately triangular shape, the iron loss reduction effect cannot be sufficiently obtained at the groove center position based on the above-described characteristics, and the motor efficiency cannot be improved.

Fig. 18 is a graph showing analysis results of the proportion [% ] of loss in the conventional example based on a reference example having the same rotor structure as the conventional example except that no groove is formed. Fig. 18(a) is a diagram showing a loss ratio in a low-load low-speed region of the motor. Fig. 18(b) is a diagram showing a ratio of loss in a high-load high-speed region of the motor. This figure shows the case where the loss of the conventional example is equivalent to that of the reference example having no groove, particularly in the low-load low-speed region stably utilized in the vehicle driving motor, and the motor efficiency cannot be improved even if the groove is formed.

The inventors of the present application have found that the above-described problems can be solved by expanding the shape of the groove in the circumferential direction and defining the starting point and the ending point of the groove on the outer periphery of the rotor in consideration of the positional relationship with the permanent magnets constituting the magnetic poles. The details will be described below.

The shape of the groove 10 of the present embodiment will be described with reference to fig. 1. In the following description, the electrical angle defined is defined in a region between the d-axis and an adjacent q-axis.

The above description has been made of the case where the start point and the end point of the groove 10 are located in the range from the tangent line a to the tangent line B. In the following description, the position of the starting point of the groove 10 is defined by θ 1, which is an electrical angle from the starting point to the d-axis, and the position of the ending point is defined by θ 2, which is an electrical angle from the ending point to the d-axis.

The end point of the groove 10 in the present embodiment is formed at a position substantially coincident with the tangent line a. That is, the end point of the groove 10 is formed at a position where θ 2 substantially coincides with the electrical angle from the tangent line a to the d-axis. The position of the start point will be described with reference to fig. 2.

Fig. 2 is a graph showing the analysis result of analyzing the iron loss reduction rate based on the position of the starting point of the groove 10 in the case where the reference example (no groove) is used as a reference (100%). The position of the starting point of the groove 10 is defined by θ 1 which is an electrical angle from the starting point to the d-axis (see fig. 1). The vertical axis represents the iron loss reduction rate [% ], and the horizontal axis represents θ 1[ ° ]. In addition, θ 1 is 0 ° and coincides with the d-axis. A broken line drawn near θ 1 ≈ 32 ° indicates θ 0 which is an electrical angle from an outermost peripheral portion of the permanent magnet 3 on the q-axis side to the d-axis. When a straight line drawn from the rotation center to the outer periphery of the rotor 6 through the outermost peripheral portion of the permanent magnet 3 is defined as a straight line D, θ 0 is defined as an electrical angle from the straight line D to the D-axis (see fig. 1).

As is clear from fig. 2, the iron loss is reduced in the region θ 1 < about 65 °, regardless of the circumferential width of the permanent magnet 3, even if the starting point is formed in the region on the q-axis side of the end portion on the q-axis side of the permanent magnet 3. Further, this figure shows that the iron loss decreases as θ 1 decreases, that is, as the starting point approaches the d-axis side. Therefore, it is understood that the motor loss is reduced and the efficiency of the motor can be improved as the starting point of the groove 10 approaches the d-axis side with θ 1 ≈ 65 ° as the upper limit. Next, the lower limit of the start point will be described with reference to fig. 3.

Fig. 3 is a diagram showing an analysis result of analyzing a change in stress of the bridge portion 7 based on the position of the start point of the groove 10 with reference to the above reference example (reference value of 1). θ 1 ≈ 44 ° coincides with an electrical angle between a tangent B (see fig. 1) drawn from the rotation center to the outer periphery of the rotor 6 through the q-axis side end portion of the gap 5 and the d-axis. As can be seen from this figure, when the starting point of the groove 10 is formed at a position where θ 1 is less than about 44 °, the stress of the bridge portion 7 increases as θ 1 decreases, that is, as the starting point moves toward the d-axis side of the bridge portion 7. Therefore, the starting point of the groove 10 is set to be formed on the q-axis side of the bridge portion 7.

The bridge 7 is the thinnest portion in the surface direction of the rotor 6, and is the portion where the stress applied is the largest when the permanent magnet 3 is held by centrifugal force so as not to fly out to the outer periphery when the rotor 6 is driven. Therefore, the bridge 7 needs to be designed to have a stress not exceeding its material fatigue strength. In view of this, the lower limit of the starting point of the groove 10 is set to be on the q-axis side of the q-axis side end of the gap 5 based on the analysis result shown in fig. 3, whereby the strength of the bridge portion 7 can be secured and the iron loss can be reduced.

Next, the reason why the iron loss is reduced by the groove 10 formed as described above will be described with reference to fig. 4. In addition, the iron loss in this specification includes stator iron loss and rotor iron loss.

Fig. 4 is a diagram for explaining an analysis result of analyzing a change in magnetic flux density of the stator based on the outer peripheral shape of the rotor 6. This figure shows a waveform of the magnetic flux density of the stator corresponding to the outer peripheral shape of the rotor 6. The solid line represents the present embodiment, the chain line represents the conventional example, the chain double-dashed line represents the reference example, and the broken line represents the ideal waveform (sine wave). In addition, a broken line L1 indicates the d-axis, L2 indicates the starting point of the groove 10 in the present embodiment, L3 indicates the starting point of the groove in the conventional example, and L4 indicates the ending point of the groove 10 in the present embodiment and the groove in the conventional example.

As a premise, the magnetic flux waveform of the rotor having a single magnetic pole in which 3 permanent magnets are arranged in a substantially triangular shape is a combination of the magnet magnetic flux from the pair of permanent magnets 2 arranged in a V-shape and the magnet magnetic flux from the permanent magnet 3, and therefore contains many harmonic components. If a slot is provided in the outer periphery of such a rotor, the magnetic resistance of the slot portion increases, and therefore the magnetic flux of the magnet that links from the slot portion to the stator side decreases. That is, by setting the circumferential width of the groove and controlling the magnet magnetic flux (rotor magnetic flux) from the rotor 6, the magnetic flux waveform can be brought close to a sine wave which is an ideal waveform shape. As a result, harmonic components of the magnetic flux density of the stator are reduced by making the rotor magnetic flux close to a sine wave.

As shown in fig. 4, it is understood that the circumferential width of the groove 10 in the present embodiment is larger than that in the conventional example, and the magnetic flux waveform is closer to an ideal sinusoidal wave than that in the conventional example. Further, by setting the starting point of the groove 10 to the d-axis side of L3, which is the starting point of the conventional example, the magnetic flux waveform of the present embodiment can be made closer to an ideal sinusoidal wave than at least the conventional example.

Fig. 5 is a graph showing analysis results of the motor loss ratio [% ] of the conventional example and the present embodiment, in the case of the reference example (no groove) as a reference (100%). Fig. 5(a) is a diagram showing a loss ratio in a low-load low-speed region of the motor. Fig. 5(b) is a diagram showing a ratio of loss in a high-load high-speed region of the motor. As is clear from the figure, the rotor 6 of the present embodiment can reduce motor loss as compared with the reference example and the conventional example. Here, the iron loss is mainly composed of a hysteresis loss and an eddy current loss. Since the hysteresis loss is proportional to the frequency of the magnetic flux waveform and the eddy current loss is proportional to the square of the frequency, the magnetic flux waveform can be approximated to a sine wave, and the harmonic component of the magnetic flux density of the stator can be suppressed, whereby the iron loss at the time of high-speed rotation can be greatly reduced.

That is, in the rotor 6 of the present embodiment, the rotor magnetic flux is made to approach a sinusoidal wave by the slots 10, so that the iron loss can be reduced, and as a result, the motor loss can be reduced and the motor efficiency can be improved not only in the high-load high-speed region but also in the low-load low-speed region which is a stable region, as shown in fig. 5 (a).

Next, the position of the starting point of the groove 10, which contributes to the improvement of the torque performance of the rotor 6, will be described. If the torque performance of the rotor 6 is improved, a large torque can be output with a small current, and therefore, as a result, the motor loss can be reduced.

Fig. 6 is a diagram for explaining a start point of the groove 10 defined from the viewpoint of improving torque performance. As described above, the position of the start point is defined by the electrical angle θ 1 with respect to the d-axis. Further, an electrical angle from the outermost peripheral portion of the permanent magnet 3 on the q-axis side to the d-axis is defined by θ 0. When a straight line drawn from the rotation center to the outer periphery of the rotor 6 through the outermost peripheral portion on the q-axis side of the permanent magnet 3 is defined as a straight line C, an electrical angle from the straight line C to the d-axis is defined as θ i.

If the above assumption is made, the starting point of the groove 10 is formed to satisfy the following expression (1).

[ equation 1]

(θi-θ0)/3+θ0＜θ1…(1)

The reason why the starting point of the groove 10 satisfies the formula (1) will be described with reference to fig. 7.

Fig. 7 is a graph showing an analysis result of analyzing a change in the 1 st order component of the induced voltage based on the position of the starting point of the slot 10. The horizontal axis represents θ 1[ ° ], and represents the proportion [% ] of the 1 st order component of the induced voltage in the case of the reference example (no groove) as a reference (100%). In addition, a broken line drawn at θ 1 ≈ 32 ° indicates θ 0 as an electrical angle from an outermost peripheral portion of the permanent magnet 3 on the q-axis side to the d-axis, and a broken line drawn at θ 1 ≈ 78 ° indicates θ i as an electrical angle from an outermost peripheral portion of the permanent magnet 2 to the d-axis. In the drawing, a broken line drawn at θ 1 ≈ 47 ° indicates an electrical angle satisfying the expression (1) in the present embodiment. The first order component of the induced voltage shown in the figure is a fundamental wave of the induced voltage from which the harmonic component is removed.

Here, the torque of the IPM motor is a torque obtained by combining the magnet torque and the reluctance torque. The magnet torque increases in proportion to the magnitude of the 1 st order component of the induced voltage generated by the magnet magnetic flux flowing from the rotor 6 to the stator.

As shown in fig. 7, when the starting point of the groove 10 is formed at a position where θ 1 satisfies the above expression (1), the torque performance can be improved as compared with the reference example in which no groove is formed. This is because, by forming the starting point of the groove 10 at a position satisfying the above expression (1), the magnetic flux of the magnet contributing to the torque can be further guided to the d-axis side, and the first order component of the induced voltage can be increased. In this way, by setting θ 1 to satisfy the above expression (1), a large torque can be output with a small current, and therefore the motor loss can be reduced.

The upper limit of θ 1 may be set to an electrical angle that satisfies the desired torque performance. For example, based on the analysis results in fig. 7, the upper limit of the range in which the torque performance is improved as compared with the reference example may be set to approximately θ 1 ≈ 68 °. However, if the above iron loss reduction effect is considered using fig. 2, θ 1 may be about 65 ° or so as to be preferable, and thus, may be appropriately set in accordance with the purpose.

Next, a position of a starting point of the slot 10, which can effectively reduce the cogging torque, will be described. The cogging torque is a positive and negative torque generated by a relative positional relationship between the stator and the rotor when the rotor rotates even when no current is supplied, and is a torque that causes vibration and noise of the motor.

Fig. 8 is a diagram for explaining a position of a starting point of the slot 10 which is advantageous for reduction of the cogging torque. In the upper part of the figure, the harmonic components of the torque ripple corresponding to the outer peripheral shape of the rotor 6 shown in the lower part of the figure are shown corresponding to the electrical angle [ ° ] with the d-axis as a starting point.

The position of the starting point of the slot 10 capable of effectively reducing the cogging torque is defined as, for example, a position of the starting point of the slot 10 set in a range capable of reducing the cogging torque as compared with a reference example in which no slot is formed. Here, as described above in fig. 8, a plurality of scale points, which are graduated at intervals of an electrical angle of 1 cycle of the harmonic component of the torque ripple with respect to the range from the d axis to the q axis, are set as points E on the outer periphery of the rotor 6. In this case, the starting point of the groove 10 in the present embodiment is formed in a region shifted from a position shifted by 1/5 cycles toward the d-axis side to a position shifted by 1/3 cycles toward the q-axis side with reference to the point E (see double arrows in the figure). The effect of reducing the cogging torque in the case where the grooves 10 are formed in the above-described manner will be described with reference to fig. 9.

Fig. 9 is a diagram showing an analysis result of analyzing a change in cogging torque based on the position of the starting point of the slot 10. In the upper part of the figure, the ratio [% ] of the cogging torque corresponding to θ 1 at the position of the starting point of the predetermined groove 10 is shown with reference example (no groove) as a reference (100%). On the other hand, in the lower part of the figure, the harmonic component of the torque ripple, which is an index when the position of the start point of the groove 10 is defined, is shown by θ 1[ ° ].

As shown in the drawing, when the starting point of the slot 10 is formed in the region shifted from the position shifted from 1/5 cycles toward the d-axis side to the position shifted from 1/3 cycles toward the q-axis side with reference to the point E, the cogging torque can be effectively reduced as compared with the reference example in which no slot is formed. This makes it possible to provide a motor in which vibration and noise are suppressed as compared with the reference example.

In consideration of the above equation (1), the position of the starting point of the groove 10 in the case where both the reduction of the cogging torque and the improvement of the torque are satisfied will be described with reference to fig. 10.

Fig. 10 is a graph showing the analysis result of analyzing the change of the cogging torque and the 1 st-order component of the induced voltage based on the position of the starting point of the slot 10. Fig. 10 is a diagram showing a change in the induced voltage 1-order component corresponding to the starting point position of the slot 10 described in fig. 7, superimposed on the above-described fig. 9. A line drawn near θ 1 ≈ 47 ° is an electrical angle satisfying (θ i- θ 0)/3+ θ 0 expressed by the above equation (1).

As shown in the drawing, when the starting point of the slot 10 is formed in the region shifted from the position shifted by 1/5 cycles toward the d-axis side to the position shifted by 1/3 cycles toward the q-axis side with reference to the point E, the cogging torque can be effectively reduced as compared with the reference example in which no slot is formed. Further, it is found that, in the case of achieving both the reduction of the cogging torque and the improvement of the torque, it is preferable to form the starting point of the groove 10 in a region from a position shifted by 1/5 cycles toward the d-axis side to a position shifted by 1/3 cycles toward the q-axis side with reference to the point E in the vicinity of θ 1 ≈ 60 ° in consideration of (θ i — θ 0)/3+ θ 0 < θ 1 expressed by the above expression (1). By specifying the position of the starting point of the slot 10 in this manner, it is possible to provide a motor that achieves both reduction of cogging torque and improvement of torque, has a small motor loss, is efficient, and reduces vibration.

Next, the position of the starting point of the groove 10 described with reference to fig. 10 is expressed by an equation. Generalization is achieved by the formula, and the method can be easily used for design. That is, when the number of times of the harmonic component of the torque ripple is n and the electrical angle from the outermost peripheral portion on the q-axis side of the permanent magnet 3 to the d-axis is θ 0, and when the minimum integer satisfying mx (2 pi/n) > θ 0 is m, the starting point of the slot 10 is formed in a range from a position satisfying the following expression (2) to a position satisfying the following expression (3).

[ equation 2]

m×(2π/n)-(2π/n)/5…(2)

[ equation 3]

m×(2π/n)-(2π/n)/3…(3)

Even when the position of the starting point of the slot 10 is defined based on such an equation, as described with reference to fig. 10, it is possible to provide a motor in which both reduction of the cogging torque and improvement of the torque are achieved, the motor loss is small, the efficiency is high, and the vibration is reduced.

Next, the depth of the groove 10 is defined.

Fig. 11 is a diagram for explaining the depth d of the groove 10. The depth d of the groove 10 is defined as a distance from the deepest point on the rotation center side to the virtual outer periphery on a line F drawn from the rotation center of the rotor 6 to the virtual outer periphery of the rotor 6 through the deepest point on the rotation center side of the groove.

The rotor 6 is accommodated on the inner circumferential side of the stator 20 through a space (gap 21) of a predetermined distance. The length g of the gap 21 is defined as the shortest distance connecting the inner periphery of the stator 20 and the outer periphery of the rotor 6. In this case, the depth d of the groove 10 is formed to satisfy d.ltoreq.4Xg.

Fig. 12 is a graph showing the analysis result of analyzing the iron loss reduction rate based on the depth d of the groove 10 in the case of the reference example (no groove) (iron loss reduction rate: 100%, cogging torque: 1). The depth d of the groove 10 shown on the horizontal axis is represented by a multiple of the length a of the gap 21. As shown in the figure, for example, as described above, the depth d of the slot 10 is set to d ≦ 4 × g, whereby a motor with reduced iron loss and low cogging torque can be provided. Further, if the depth d of the groove 10 is set to d > 4 × g, the iron loss gradually increases, which is not preferable. This is because the magnetic flux waveform of the present embodiment shown in fig. 4 deviates from an ideal sine wave system as the depth of the groove 10 increases.

As described above, the rotor (rotor 6) of the rotating electric machine according to the present embodiment has a plurality of single magnetic poles arranged in the circumferential direction, and the single magnetic poles are configured by: a pair of 1 st permanent magnets (permanent magnets 2) arranged in a V shape open in the outer circumferential direction; and a 2 nd permanent magnet (permanent magnet 3) disposed in the open portion of the V-shape, and having: a 1 st gap (gap 4) provided continuously with the magnet insertion hole 40 at an end portion on the q-axis side electrically orthogonal to the d-axis constituted by the single magnetic pole, in the magnet insertion hole 40 into which the permanent magnet 2 is inserted; a 2 nd space (space 5) provided continuously with the magnet insertion hole 50 at both end portions of the magnet insertion hole 50 into which the permanent magnet 3 is inserted; and a groove 10 formed in the outer periphery of the rotor 6 in the axial direction of the rotor 6. When a straight line drawn out to the outer periphery through the rotation center of the rotor 6 and the d-axis side end of the gap 4 is a straight line a, and a straight line drawn out to the outer periphery through the rotation center and the q-axis side end of the gap 5 is a straight line B, the q-axis side end (end point) of the groove is located on the straight line a, and the d-axis side end (start point) of the groove is located on the q-axis side of the straight line B.

This makes the waveform of the magnetic flux from the rotor 6 close to a sine wave, which is an ideal waveform shape, and reduces the harmonic component of the magnetic flux density of the stator, thereby reducing the iron loss and improving the motor efficiency. Further, the starting point of the groove 10 is set to be located on the q-axis side of the straight line B, and the radial width of the bridge portion 7 is not reduced, so that the stress of the bridge portion 7 is not deteriorated.

In addition, according to the rotor 6 of the rotating electrical machine of the embodiment, when the electrical angle from the D-axis side end of the slot 10 to the D-axis is θ 1 and the straight line drawn from the rotation center to the outer periphery through the outermost peripheral portion of the permanent magnet 2 is a straight line C, when the electrical angle from the straight line C to the D-axis is θ i and the straight line drawn from the rotation center to the outer periphery through the outermost peripheral portion of the permanent magnet 3 is a straight line D, when the electrical angle from the straight line D to the D-axis is θ 0, the D-axis side end of the slot 10 is formed at a position satisfying (θ i- θ 0)/3+ θ 0 < θ 1. This allows the magnet, which contributes to torque, to be magnetically guided to the d-axis side, and the primary component of the induced voltage can be increased, so that a large torque can be output with a small current, and motor loss can be reduced.

In addition, according to the rotor 6 of the rotating electrical machine of the embodiment, when a plurality of scale points obtained by scaling the d axis to the q axis at electrical angular intervals of 1 cycle of the harmonic component of the torque ripple on the outer periphery of the rotor 6 are set as the point E, the d axis side end of the groove is formed in a region shifted from a position shifted from the point E by 1/5 cycles toward the d axis side to a position shifted from the point E by 1/3 cycles toward the q axis side with reference to the point E. As a result, the cogging torque can be reduced as compared with the reference example in which no groove is formed, and thus a motor in which vibration and noise are suppressed can be provided.

In addition, according to the rotor 6 of the rotating electrical machine of the embodiment, when the number of times of the harmonic component of the torque ripple is n and the minimum integer satisfying mx (2 pi/n) > θ 0 is m, the d-axis side end portion of the slot 10 is formed in the region from the position satisfying mx (2 pi/n) - (2 pi/n)/5 to the position satisfying mx (2 pi/n) - (2 pi/n)/3. By specifying the position of the starting point of the slot 10 in this way, it is possible to provide a motor that achieves both reduction of cogging torque and improvement of torque, has a small motor loss, is efficient, and reduces vibration. The position of the starting point of the groove 10 having such an effect can be generalized by an equation and can be easily used for design.

The rotor 6 of the rotating electrical machine according to one embodiment further includes a stator (stator)20 that houses the rotor 6 on the inner peripheral side, and the slot 10 is formed so as to satisfy d ≦ 4 × g when a distance of a gap 21 between the inner periphery of the stator 20 and the outer periphery of the rotor 6 is g, a distance from a deepest point on the rotation center side of the slot 10 to a virtual outer periphery of the rotor 6 on a line drawn from the rotation center of the rotor 6 to the virtual outer periphery of the rotor 6 is d, and a distance from the deepest point on the rotation center side to the virtual outer periphery is d. This can provide a motor with reduced iron loss and low cogging torque.

Next, another modification having the features of the rotor 6 according to the embodiment described above, that is, another modification having the groove 10 formed on the outer periphery of the rotor core 1 based on the above-described regulations will be described. The rotor structure described below can obtain the same technical effects as those described in the embodiment by providing the groove 10 having the above-described characteristics.

(modification 1)

Fig. 13 is a diagram for explaining the shape of the groove 10 according to modification 1. As shown in the figure, the shape of the groove 10 may not necessarily be triangular, and may be rectangular as shown in the figure.

(modification 2)

Fig. 14 is a diagram for explaining the shape of the groove 10 according to modification 2. As shown in the figure, the shape of the groove 10 may be formed in a circular arc shape convex toward the rotation center side.

(modification 3)

Fig. 15 is a diagram for explaining the shape of the groove 10 according to modification 3. As shown in the figure, the shape of the groove 10 may be formed in a trapezoidal shape protruding toward the rotation center side.

(modification 4)

Fig. 16 is a diagram for explaining the shape of the groove 10 according to modification 4. As shown, the groove 10 may be formed to include a deeper groove 11 of one or more in a part thereof. In this case, the depth d of the groove defined above is set to the depth of the deepest groove (groove 11) of the grooves 10.

While the embodiments and the modifications of the present invention have been described above, the embodiments and the modifications merely illustrate a part of the application examples of the present invention, and the technical scope of the present invention is not limited to the specific configurations of the embodiments. For example, although the above description has been made on the case where the

spaces

4 and 5 are space portions, the spaces need not be spaces, and may be filled with a nonmagnetic material such as a resin material.

The shape of the

gaps

4 and 5 of the rotor 6 is not limited to the shape shown in fig. 1 and the like, and may be appropriately changed. For example, although the gap 4 disclosed in fig. 1 and the like has a strip shape formed substantially parallel to the q-axis at the end of the permanent magnet 2 on the q-axis side, the gap may have a curved shape as shown in fig. 17. In this case, as shown in the figure, a line drawn out to the outer periphery through the rotation center of the rotor and the d-axis side end of the gap 4 is defined as a straight line a.

Claims

1. A rotor of a rotating electric machine, wherein a plurality of single magnetic poles are arranged in a circumferential direction, and the single magnetic poles are composed of: a pair of 1 st permanent magnets arranged in a V-shape open in the outer circumferential direction; and a 2 nd permanent magnet disposed at an opened portion of the V-shape,

the rotor of the rotating electric machine includes:

a 1 st air gap provided in the magnet insertion hole into which the 1 st permanent magnet is inserted, continuously to the magnet insertion hole at an end portion on a q-axis side electrically orthogonal to a d-axis constituted by the single magnetic pole;

a 2 nd gap provided to be continuous with the magnet insertion hole at both end portions of the magnet insertion hole into which the 2 nd permanent magnet is inserted; and

a groove formed in an outer periphery of the rotor in an axial direction of the rotor,

when a straight line drawn to the outer periphery through the rotation center of the rotor and the d-axis side end of the 1 st gap is a straight line a, and a straight line drawn to the outer periphery through the rotation center and the q-axis side end of the 2 nd gap is a straight line B, the q-axis side end of the groove is located on the straight line a, and the d-axis side end of the groove is located on the q-axis side of the straight line B.

2. The rotor of a rotary electric machine according to claim 1,

when an electrical angle from a d-axis side end of the groove to the d-axis is set to theta 1,

a straight line drawn from the rotation center to the outer periphery through the outermost peripheral portion of the 1 st permanent magnet is defined as a straight line C, an electrical angle from the straight line C to the d-axis is defined as θ i,

when a straight line drawn from the rotation center to the outer periphery through the outermost peripheral portion of the 2 nd permanent magnet is defined as a straight line D, and an electrical angle from the straight line D to the D-axis is defined as θ 0,

the end portion on the d-axis side of the groove is formed at a position satisfying (thetai-theta0)/3 + theta0 < theta1.

3. The rotor of a rotary electric machine according to claim 1 or 2,

when a plurality of scale points obtained by marking the d axis to the q axis at electrical angle intervals of 1 cycle of a harmonic component of torque ripple on the outer periphery of the rotor are set as points E,

the d-axis end of the groove is formed in a region shifted from a position shifted by 1/5 cycles toward the d-axis to a position shifted by 1/3 cycles toward the q-axis with respect to the point E.

4. The rotor of a rotary electric machine according to claim 3,

the number of higher harmonic components of the torque ripple is set to n,

in the case where m is the smallest integer satisfying mx (2 pi/n) > θ 0,

the d-axis side end of the groove is formed in a region from a position satisfying mx (2 pi/n) - (2 pi/n)/5 to a position satisfying mx (2 pi/n) - (2 pi/n)/3.

5. The rotor of a rotary electric machine according to claim 1 or 2,

the rotor of the rotating electrical machine further includes a stator that houses the rotor on an inner peripheral side,

the gap distance between the inner periphery of the stator and the outer periphery of the rotor is set to g,

wherein d represents a distance from a deepest point on the rotation center side to a virtual outer periphery of the rotor core on a line drawn from the rotation center of the rotor to the virtual outer periphery of the rotor core through the deepest point on the rotation center side of the slot,

the groove is formed so as to satisfy d ≦ 4 × g.