WO2018235145A1

WO2018235145A1 - Rotating electric machine rotor

Info

Publication number: WO2018235145A1
Application number: PCT/JP2017/022580
Authority: WO
Inventors: 浩平室田; 健池見; 徹仲田
Original assignee: 日産自動車株式会社
Priority date: 2017-06-19
Filing date: 2017-06-19
Publication date: 2018-12-27
Also published as: CN111052546A; JP6821022B2; JPWO2018235145A1; CN111052546B

Abstract

The rotating electric machine rotor according to one embodiment of the present invention has a plurality of magnetic poles arranged in a circumferential direction, said magnetic poles each being constituted by a pair of first permanent magnets arranged in a V-shape opening in the outer circumferential direction and a second permanent magnet arranged in a section where the V-shape opens. The rotating electric machine rotor is provided with: a first air gap provided, at an end portion of a magnet insertion hole into which the first permanent magnets are inserted, continuously from said magnet insertion hole, said end portion being located on the side of the q-axis electrically orthogonal to the d-axis constituted by one magnetic pole; a second air gap provided, at both end portions of a magnet insertion hole into which the second permanent magnet is inserted, continuously from said magnet insertion hole; and a groove formed on the outer circumference of the rotor along the axis direction of the rotor. When a line drawn through the rotation center of the rotor and the end portion of the first air gap on the d-axis side up to the outer circumference is defined as a line A and a line drawn through the rotation center and the end portion of the second air gap on the q-axis side up to the outer circumference is defined as a line B, the end portion of the groove on the q-axis side is located on the line A and the end portion of the groove on the d-axis side is located on the q-axis side from the line B.

Description

Rotor of electric rotating machine

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

As a driving motor of an electric vehicle such as an electric car or a hybrid vehicle, an embedded permanent magnet type motor (interior permanent magnet motor (hereinafter referred to as an IPM motor as appropriate)) in which permanent magnets are embedded in a rotor core is known. .

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

Furthermore, from the viewpoint of securing the durability of the inverter component, it is also necessary to make the peak value of the induced voltage not exceed the withstand voltage of the inverter system. The induced voltage is a combination of the main component contributing to the torque and the harmonic component not contributing to the torque, but if the induced voltage is simply lowered so as not to exceed the withstand voltage of the inverter system, the main component becomes smaller and the torque is reduced. It may decrease. Therefore, in order to prevent a decrease in torque, it is necessary to reduce the peak value of the induced voltage by reducing only the harmonic component.

In order to meet these requirements, JP5516739B uses a total of three permanent magnets: a pair of V-shaped permanent magnets that open in the outer circumferential direction and a permanent magnet that is disposed in the V-shaped open portion. There has been proposed a rotor structure in which one magnetic pole is formed and a groove is formed on the outer periphery. According to the rotor structure proposed herein, by forming the groove, it is possible to provide a motor with reduced cogging torque and induced voltage while reducing iron loss.

However, since the groove disclosed in JP5516739B only defines the center position on the outer periphery of the rotor, depending on the circumferential width of the permanent magnet disposed on the outermost periphery, sufficient iron loss reduction effect can be obtained. The present inventors have found that there is a problem in that the motor efficiency can not be improved.

Therefore, in the present invention, the iron loss reduction effect can be sufficiently obtained by defining the circumferential width of the groove formed on the outer periphery of the rotor while considering the positional relationship with the permanent magnet disposed on the outermost periphery. Aims to provide a rotor that can be

The rotor of the rotating electrical machine according to one aspect of the present invention is configured of a pair of first permanent magnets disposed in a V-shape that opens in the outer circumferential direction, and a second permanent magnet disposed in an open portion of the V-shape. Rotor of a rotating electrical machine in which a plurality of magnetic poles are arranged in the circumferential direction, and in the magnet insertion hole into which the first permanent magnet is inserted, the q axis side electrically orthogonal to the d axis of the magnetic poles A first air gap provided continuously with the magnet insertion hole at the end of the magnet, and a second air gap provided continuously with the magnet insertion hole at both ends of the magnet insertion hole into which the second permanent magnet is inserted And a groove formed along an axial direction of the rotor on an outer periphery of the rotor. Then, a straight line drawn to the outer periphery through the rotation center of the rotor and the d-axis end of the first air gap is taken as a straight line A, and drawn to the outer periphery through the rotation center and the q-axis side end of the second air gap When the straight line 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.

Embodiments of the present invention will be described in detail below in conjunction with the attached drawings.

FIG. 1 is a figure for demonstrating the rotor structure of one Embodiment. FIG. 2 is a diagram showing an analysis result in which the iron loss reduction rate at the position of the groove start point is analyzed. FIG. 3 is a diagram showing an analysis result obtained by analyzing a change in stress of the bridge portion according to the position of the start point of the groove. FIG. 4 is a diagram for explaining an analysis result obtained by analyzing the magnetic flux density in the stator according to the outer peripheral shape of the rotor. FIG. 5 is a diagram showing an analysis result obtained by analyzing the ratio of motor loss in the conventional example and one embodiment. FIG. 6 is a diagram for explaining the starting point of the groove defined from the viewpoint of improving the torque performance. FIG. 7 is a diagram showing an analysis result in which a change in the first-order component of the induced voltage according to the position of the start point of the groove is analyzed. FIG. 8 is a diagram for explaining the position of the start point of the groove which contributes to the reduction of the cogging torque. FIG. 9 is a diagram showing an analysis result obtained by analyzing a change in cogging torque depending on the position of the groove start point. FIG. 10 is a diagram showing an analysis result in which changes in the cogging torque and the first-order component of the induced voltage according to the position of the groove start point are analyzed. FIG. 11 is a diagram for explaining the depth d of the groove. FIG. 12 is a diagram showing an analysis result in which the iron loss reduction rate by the depth d of the groove is analyzed. FIG. 13 is a view for explaining the groove of the first modification. FIG. 14 is a view for explaining the groove of the second modification. FIG. 15 is a view for explaining the groove of the third modification. FIG. 16 is a view for explaining the groove of the fourth modification. FIG. 17 is a diagram for explaining another modification. FIG. 18 is a diagram showing an analysis result in which the ratio of loss in the conventional example to the reference example is analyzed.

-Embodiment-
FIG. 1 is a view for explaining a rotor of an embodiment to which the present invention is applied. Shown in the figure is a configuration view of a rotor (rotor) 6 included in a rotating electric machine constituting an electric motor or a generator, as viewed from a cross section perpendicular to the axial direction, which is a part of the entire configuration (one pole Minutes). The rotating electric machine according to the present embodiment is a so-called IPM (Interior Permanent Magnet) type rotating electric machine in which permanent magnets are embedded in the rotor 6, and a total of three permanent magnets, a pair of permanent magnets 2 and permanent magnets 3. And a rotor having a plurality of magnetic poles formed by permanent magnet groups 30.

Although an 8-pole structure rotor is taken as an example here, the number of poles is not limited to this. However, various analysis data to be described below are constituted by the rotor 6 having an eight-pole structure and a stator (not shown) in which the number of slots is 48 and the stator winding is wound by distributed winding. It is assumed that the present invention is applied and analyzed to the above-described rotating electrical machine.

The rotor core (rotor core) 1 is formed in a cylindrical shape by a so-called laminated electromagnetic steel sheet structure formed by axially laminating a plurality of electromagnetic steel sheets having a thickness of several hundreds of μm punched into an annular shape. Further, in the rotor core 1, a magnet insertion hole 40 (hereinafter, also simply referred to as magnet hole 40) for embedding the permanent magnet 2 and a magnet insertion hole 50 (hereinafter simply referred to as the magnet hole 50) for embedding the permanent magnet 3. Air gaps 4 (first air gaps) at both circumferential end portions of the magnet hole 40, and air gaps 5 (second air gaps) at respective circumferential end portions of the magnet holes 50, respectively. It is formed continuously.

Magnet holes

40 and 50 are holes formed by laminating in the axial direction electromagnetic steel sheet veneers in which spaces for respectively embedding two permanent magnets 2 and one permanent magnet 3 are formed. is there.

The magnet hole 40 is a center portion in the circumferential direction, and a portion located closest to the rotation center is located on the d axis, and both end portions in the circumferential direction are away from the d axis and approach the q axis while approaching the rotor outer periphery. V-shaped.

The magnet hole 50 is formed linearly along the circumferential direction of the rotor core 1 in the open portion of the V-shaped magnet hole 40.

The permanent magnet group 30 is embedded in the magnet hole 40 and the magnet hole 50, and one permanent magnet 2 is embedded in one magnet hole 40, and one permanent magnet 3 is embedded in one magnet hole 50. It is done.

As illustrated, since the magnet holes 40 are linearly symmetrical with respect to the d-axis, the pair of permanent magnets 2 also has a V-shaped arrangement that is linearly symmetrical with respect to the d-axis and opens in the outer peripheral direction. The pair of permanent magnets 2 disposed in the magnet holes 40 and the permanent magnets 3 circumferentially disposed in the V-shaped open portion form a substantially triangular shape. In the rotor 6, one magnetic pole constituted by such a substantially triangular permanent magnet group 30 is formed at a constant mechanical angle. Since the rotor 6 of the present embodiment has an eight-pole structure, permanent magnet groups 30 arranged in a substantially triangular shape are formed at a mechanical angle of 45 degrees. FIG. 1 shows that one pole.

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

magnet holes

40 and 50 of the rotor core 1. Further, in the one magnetic pole formed by the permanent magnet group 30, the magnetic poles formed by the permanent magnet group 30 are equally spaced from each other along the circumferential direction of the rotor 6, and the polarities of adjacent magnetic poles are different from each other. Will be placed. The direction of the magnetic flux generated by the permanent magnet group 30 is the d-axis (magnetic pole center), and the direction electrically perpendicular to the d-axis is the q-axis.

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

Similarly, the permanent magnet 3 is formed such that the width in the longitudinal direction (circumferential direction) is smaller than that of the magnet hole 50, and the circumferential end portions of the magnet hole 50, in other words, the portion on the q axis side of the permanent magnet 3 The air gap 5 is formed as a space portion continuous with the magnet hole 50. These space portions have lower permeability than the electromagnetic steel sheet, that is, greater magnetic resistance. Therefore, the

air gaps

4 and 5 act as magnetic barriers (flux barriers) to which the magnetic flux (flux) does not easily pass in the magnetic circuit in which the permanent magnet groups 30 constitute the rotor 6.

Then, a groove 10 is formed on the outer periphery of the rotor core 1 of the present embodiment toward the rotation center side of the rotor core 1 and along the axial direction of the rotor core 1. The groove 10 is formed on the outer periphery of the rotor core 1 in a region from the end of the air gap 4 on the d axis side to the end of the air gap 5 on the q axis side.

Referring to FIG. 1, a tangent drawn from the rotation center of rotor core 1 to the outer periphery of rotor core 1 through the tip of air gap 4 on the d axis side is taken as tangent A, and q axis of air gap 5 from rotation center of rotor core 1. Assuming that a tangent drawn to the outer periphery of the rotor core 1 through the tip is a tangent B, the groove 10 has an end (starting point) on the d axis side and an end (end point) on the q axis side in the circumferential width. Are formed to fit in the region between the tangent A and the tangent B. Details of the definition of the start point and the end point of the groove 10 will be described later.

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

Here, before describing the details of the groove 10, the conventional rotor structure, and the characteristics and problems caused by the structure will be described.

In JP5516739B (conventional example), a rotor structure is proposed in which one magnetic pole is configured by arranging a total of three permanent magnets in a substantially triangular shape, and a groove is formed on the outer periphery of a rotor core. It is disclosed in the above document that the groove can achieve an iron loss reducing effect by setting the groove center position. More specifically, the groove has a groove center position between the outermost permanent magnet and the q axis among a plurality of nick points cut at electrical angle intervals of one period of a torque ripple harmonic component. It is formed in the range of 1⁄4 cycle in the d-axis direction and 1⁄8 cycle in the q-axis direction with reference to the dividing point in the area of. According to such a rotor structure, it is possible to provide a motor with reduced cogging torque and induced voltage while reducing iron loss.

However, the inventors of the present invention have an iron loss reducing effect at the groove center position based on the above-mentioned feature, depending on the circumferential width of the outermost permanent magnet among the three permanent magnets forming the substantially triangular shape. It has been found that there are problems that can not be obtained sufficiently and the motor efficiency can not be improved.

FIG. 18 is a diagram showing an analysis result obtained by analyzing the ratio [%] of the loss in the conventional example based on the reference example having the same rotor structure as the conventional example except that no groove is formed. . FIG. 18 (a) is a diagram showing the rate of loss in the low load low speed region of the motor. FIG. 18B is a diagram showing the ratio of loss in the high load high speed region of the motor. In the figure, the loss of the conventional example is equivalent to that of the reference example having no groove particularly in a low load low speed region which is constantly utilized in a vehicle drive motor, and the motor efficiency is improved even if the groove is formed. It shows that you can not let it go.

The inventors of the present invention expanded the shape of the groove in the circumferential direction, and considered the positional relationship between the start point and the end point of the groove on the rotor outer periphery with the permanent magnet constituting the magnetic pole. It has been found that this can be solved by the above definition. Details will be described below.

Returning to FIG. 1, the definition of the shape of the groove 10 of the present embodiment will be described. Note that the electrical angle defined in the following description is defined in the region between the d-axis and the adjacent q-axis.

It has been mentioned above that the start point and the end point of the groove 10 lie in the range from tangent A to tangent B. In the following description, the position of the start point of the groove 10 is defined by θ1 which is the electrical angle from the start point to the d axis, and the position of the end point is defined by θ2 which is the electrical angle from the end point to the d axis Do.

The end point of the groove 10 of the present embodiment is formed at a position substantially coincident with the tangent A. That is, the end point of the groove 10 is formed at a position where θ2 substantially coincides with the electrical angle from the tangent A to the d-axis. The position of the start point will be described with reference to FIG.

FIG. 2 is a diagram showing an analysis result in which the iron loss reduction rate at the position of the start point of the groove 10 is analyzed when the reference example (without the groove) described above is used as a reference (100%). The position of the start point of the groove 10 is defined by θ1 which is an electrical angle from the start point to the d axis (see FIG. 1). The vertical axis indicates the iron loss reduction rate [%], and the horizontal axis indicates θ1 [°]. Note that θ1 = 0 ° coincides with the d axis. The dotted line drawn near θ1θ32 ° indicates θ0, which is the electrical angle from the outermost periphery of the permanent magnet 3 on the q axis side to the d axis. Note that θ0 is defined as an electrical angle from the straight line D to the d-axis when a straight line drawn from the center of rotation to the outer periphery of the rotor 6 through the outermost circumference of the permanent magnet 3 is straight line D (FIG. 1) reference).

From FIG. 2, regardless of the circumferential width of the permanent magnet 3, even if the start point is formed in the area on the q axis side of the end of the permanent magnet 3 on the q axis side, in the area of θ1 <about 65 ° It can be seen that iron loss is reduced. Furthermore, the figure shows that the core loss is more reduced as θ1 is smaller, that is, as the start point is closer to the d-axis side. Therefore, it can be seen that the motor loss decreases and the efficiency of the motor can be improved as the start point of the groove 10 approaches the d-axis side, with θ1 ≒ 65 ° as the upper limit. Next, the lower limit of the start point will be described with reference to FIG.

FIG. 3 is a diagram showing an analysis result in which a change in stress of the bridge portion 7 according to the position of the start point of the groove 10 is analyzed when the above-described reference example is used as a reference (reference value = 1). θ1 ≒ 44 ° coincides with the electrical angle from the tangent B (see FIG. 1) drawn from the center of rotation to the outer periphery of the rotor 6 through the q-axis end of the air gap 5 to the d-axis. From the same figure, when the start point of the groove 10 is formed at a position of θ1 <about 44 °, the bridge portion 7 becomes smaller as θ1 becomes smaller, that is, as the start point is closer to the d axis side than the bridge portion 7. It can be seen that the stress of is increased. Accordingly, the start point of the groove 10 is set to be formed on the q axis side with respect to the bridge portion 7.

The bridge portion 7 is the thinnest portion in the surface direction of the rotor 6, and is the portion most stressed when holding the permanent magnet 3 so as not to fly out by the centrifugal force when the rotor 6 is driven. Therefore, the bridge portion 7 needs to be designed so that the stress does not exceed the material fatigue strength. Taking this into consideration, based on the analysis result shown in FIG. 3, the strength of the bridge portion 7 is secured by setting the lower limit of the start point of the groove 10 closer to the q axis than the q axis end of the air gap 5. At the same time, 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. The iron loss in the present specification includes stator iron loss and rotor iron loss.

FIG. 4 is a diagram for explaining an analysis result in which a change in magnetic flux density in the stator due to the outer peripheral shape of the rotor 6 is analyzed. The figure shows the waveform of the magnetic flux density in the stator corresponding to the outer peripheral shape of the rotor 6. The solid line indicates this embodiment, the one-dot and dash line indicates the conventional example, the two-dot and dash line indicates the reference example, and the dotted line indicates the ideal waveform (sine wave). The dotted line L1 indicates the d axis, L2 indicates the start point of the groove 10 in the present embodiment, L3 indicates the start point of the groove in the conventional example, and L4 indicates the end points of the groove 10 of the present embodiment and the conventional example. There is.

As a premise, the magnetic flux waveform of the rotor having one magnetic pole configured by arranging three permanent magnets in a substantially triangular shape is the magnet magnetic flux from the pair of permanent magnets 2 arranged in a V shape and the permanent magnet 3 Because it is a composition of the magnet flux from 、, it contains many harmonic components. When the groove is provided on the outer periphery of such a rotor, the magnetic resistance of the groove portion is increased, so that the magnetic flux of the magnet interlinking from the groove portion to the stator side is reduced. That is, by controlling the magnet magnetic flux (rotor magnetic flux) from the rotor 6 by setting the circumferential width of the groove, it is possible to make the magnetic flux waveform approximate to a sine wave which is an ideal waveform shape. By bringing the rotor flux closer to a sine wave, the harmonic component of the flux density in the stator is consequently reduced.

As shown in FIG. 4, the circumferential width of the groove 10 of this embodiment is formed much wider than that of the conventional example, so that the magnetic flux waveform approaches an ideal sine wave as compared with the conventional example. Know that Further, by setting the position of the start point of the groove 10 closer to the d-axis than L3 which is the start point position of the conventional example, the magnetic flux waveform of the present embodiment is closer to at least an ideal sine wave than the conventional example. Can.

FIG. 5 is a diagram showing an analysis result obtained by analyzing the ratio [%] of motor loss in the conventional example and the present embodiment when the reference example (without the groove) is used as a reference (100%). FIG. 5A is a diagram showing the rate of loss in the low load low speed region of the motor. FIG. 5 (b) is a diagram showing the rate of loss in the high load high speed region of the motor. From the figure, it can be seen that the rotor 6 of the present embodiment can reduce the motor loss compared to the reference example and the conventional example. Here, the core loss mainly includes hysteresis loss and 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 is brought close to a sine wave to suppress harmonic components of the magnetic flux density in the stator at high rotation Iron loss can be significantly reduced.

That is, in the rotor 6 of the present embodiment, the core loss can be reduced by bringing the rotor magnetic flux closer to a sine wave by the groove 10, and as a result, as shown in FIG. In addition, the motor loss can be reduced and the motor efficiency can be improved even in the low load low speed region which is a steady region.

Next, the position of the start point of the groove 10 contributing 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 produced with less current, and as a result, the motor loss can be reduced.

FIG. 6 is a diagram for explaining the starting point of the groove 10 defined from the viewpoint of improving the torque performance. As mentioned above, the position of the starting point is defined by the electrical angle θ1 from the d-axis. Further, the electrical angle from the outermost periphery of the permanent magnet 3 on the q axis side to the d axis is defined by θ0. Then, when a straight line drawn from the center of rotation to the outer periphery of the rotor 6 through the outermost periphery of the permanent magnet 3 on the q axis side is defined as a straight line C, the electrical angle from the straight line C to the d axis is defined as θi.

Assuming the above, the starting point of the groove 10 is formed to satisfy the following formula (1).

The reason why the starting point of the groove 10 is formed so as to satisfy the equation (1) will be described with reference to FIG.

FIG. 7 is a diagram showing an analysis result in which a change in the first-order component of the induced voltage according to the position of the start point of the groove 10 is analyzed. The horizontal axis indicates the ratio [%] of the primary component of the induced voltage when θ1 [°] is used as a reference (100%) in the reference example (without the groove). Further, the dotted line drawn at θ 1 示し 32 ° indicates θ 0 which is the electrical angle from the outermost periphery of the permanent magnet 3 on the q axis side to the d axis, and the dotted line drawn at θ 1 78 78 ° indicates the permanent magnet 2 The electric angle θi from the outermost peripheral portion of to the d-axis is shown. And, a dotted line drawn to θ14747 ° in the figure indicates an electrical angle that satisfies the above equation (1) in this embodiment. The primary component of the induced voltage shown in the drawing is the fundamental wave of the induced voltage excluding the harmonic component.

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 primary component of the induced voltage generated by the magnet flux flowing from the rotor 6 to the stator.

As shown in FIG. 7, when the start point of the groove 10 is formed at a position where θ1 satisfies the above equation (1), the torque performance can be improved as compared with the reference example in which the groove is not formed. This is because, by forming the start point of the groove 10 at a position satisfying the above equation (1), the magnet magnetic flux contributing to the torque can be induced to the d axis side more, and the primary component of the induced voltage can be increased. It is because As described above, by setting θ1 so as to satisfy the equation (1), a larger torque can be output with a small current, so that the motor loss can be reduced.

The upper limit of θ1 may be set to an electrical angle that satisfies the desired torque performance. For example, based on the analysis result of FIG. 7, the upper limit may be set to about θ1 ≒ 68 ° as a range in which the torque performance is improved compared to the reference example. However, if the iron loss reduction effect described above with reference to FIG. 2 is taken into consideration, θ1 ≒ 65 ° or so may be good, so it may be set appropriately according to the purpose.

Next, the position of the start point of the groove 10 capable of effectively reducing the cogging torque will be described. The cogging torque is positive or negative torque generated due to the 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 motor vibration and noise.

FIG. 8 is a diagram for explaining the position of the start point of the groove 10 contributing to the reduction of the cogging torque. 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 in the upper part of the figure, corresponding to the electrical angle [°], with the d axis as the start point.

The position of the start point of the groove 10 capable of effectively reducing the cogging torque is, for example, the position of the start point of the groove 10 set within a range where the cogging torque can be made lower than in the reference example in which the groove is not formed. It is defined as Here, as described in the upper part of FIG. 8, a plurality of notched points obtained by cutting from the d axis to the q axis at electrical angle intervals of one period of the harmonic component of torque ripple is taken as point E on the outer periphery of the rotor 6. In this case, the start point of the groove 10 according to the present embodiment is formed in a region from a position shifted by 1⁄5 cycle on the d axis side with respect to the point E to a position shifted by 1⁄3 cycle to the q axis side See the double arrows in the figure). The cogging torque reduction effect when the groove 10 is formed in this manner will be described with reference to FIG.

FIG. 9 is a diagram showing an analysis result in which a change in cogging torque according to the position of the start point of the groove 10 is analyzed. The ratio [%] of the cogging torque according to θ1 defining the position of the start point of the groove 10 when the reference example (without the groove) is used as a reference (100%) is shown above the figure. On the other hand, in the lower part of the figure, the harmonic component of the torque ripple, which serves as an index when defining the position of the start point of the groove 10, is shown according to θ1 [°].

As shown in the drawing, when the start point of the groove 10 is formed in a region from a position shifted by 1⁄5 cycle on the d axis side with respect to the point E to a position shifted by 1⁄3 cycle to the q axis side, It can be seen that the cogging torque can be effectively reduced as compared with the reference example in which is not formed. This makes it possible to provide a motor in which vibration and noise are suppressed more than in the reference example.

Further, the position of the start point of the groove 10 in the case where the reduction of the cogging torque and the improvement of the torque are compatible will be described with reference to FIG.

FIG. 10 is a diagram showing an analysis result in which changes in the cogging torque and the first-order component of the induced voltage according to the position of the start point of the groove 10 are analyzed. FIG. 10 is a diagram in which the change of the primary component of the induced voltage according to the start point position of the groove 10 described in FIG. 7 is superimposed and displayed in FIG. 9 described above. A line drawn near θ1 ≒ 47 ° is an electrical angle that satisfies (θi−θ0) / 3 + θ0 shown in the above equation (1).

As shown in the drawing, when the start point of the groove 10 is formed in a region from a position shifted by 1⁄5 cycle on the d axis side with respect to the point E to a position shifted by 1⁄3 cycle to the q axis side, It can be seen that the cogging torque can be effectively reduced as compared with the reference example in which is not formed. Then, in order to achieve both cogging torque reduction and torque improvement, in consideration of (θi−θ0) / 3 + θ0 <θ1 represented by the above equation (1), reference is made to a point E near θ1θ60 ° It can be seen that it is more preferable to form the start point of the groove 10 in a region from a position shifted by 1⁄5 cycle on the d axis side to a position shifted by 1⁄3 cycle on the q axis side. By defining the position of the start point of the groove 10 in this manner, it is possible to achieve both a reduction in cogging torque and an improvement in torque, and to provide a motor with small motor loss, high efficiency, and reduced vibration. It becomes.

Next, the position of the start point of the groove 10 described with reference to FIG. By generalizing the equation, it can be easily used for design. That is, assuming that the order of harmonic components of torque ripple is n and the electrical angle from the outermost periphery of the permanent magnet 3 on the q axis side to the d axis is θ0, the minimum satisfying m × (2π / n)> θ0 When the integer of n is m, the start point of the groove 10 is formed in the range from the position satisfying the following expression (2) to the position satisfying the following expression (3).

Even when the position of the start point of the groove 10 is defined based on such an equation, as described above with reference to FIG. 10, the reduction of cogging torque and the improvement of torque are compatible, and the motor loss is small and high. It is possible to provide a motor that is efficient and reduced in vibration.

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 from the deepest point to the virtual outer periphery on the line F drawn from the rotational center of the rotor 6 to the virtual outer periphery of the rotor 6 through the deepest point on the rotational central side of the groove Defined as the distance of

The rotor 6 is accommodated on the inner peripheral side of the stator 20 via 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 ≦ 4 × g.

FIG. 12 is a graph showing an analysis result of an iron loss reduction rate by the depth d of the groove 10 when the reference example (no groove) is used as a reference (iron loss reduction rate: 100%, cogging torque: 1) It is. The depth d of the groove 10 indicated by the horizontal axis is represented by a multiple of the length a of the gap 21. As illustrated, by setting the depth d of the groove 10 to, for example, d ≦ 4 × g as described above, it is possible to provide a motor with a low cogging torque while reducing iron loss. If the depth d of the groove 10 is d> 4 × g, the core loss gradually increases, which is not preferable. This is because as the depth of the groove 10 is increased, the magnetic flux waveform of the present embodiment shown in FIG. 4 is separated from the ideal sine wave system.

As described above, the rotor (rotor 6) of the rotating electrical machine according to the present embodiment is disposed in the V-shaped open portion and the pair of first permanent magnets (permanent magnet 2) disposed in the V-shape opening in the outer peripheral direction. It is a rotor 6 of a rotating electrical machine in which a plurality of magnetic poles constituted by the second permanent magnets (permanent magnets 3) are arranged in the circumferential direction, and the magnetic insertion holes 40 into which the permanent magnets 2 are inserted Of the first air gap (air gap 4) provided continuously with the magnet insertion hole 40 at the end on the q axis side, which is electrically orthogonal to the d axis formed by the magnet, and the magnet insertion hole 50 in which the permanent magnet 3 is inserted A second air gap (air gap 5) provided continuously with the magnet insertion hole 50 at both end portions, and a groove 10 formed along the axial direction of the rotor 6 on the outer periphery of the rotor 6 are provided. Then, a straight line drawn to the outer periphery through the rotation center of the rotor 6 and the d-axis side end of the air gap 4 is taken 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 air 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 (starting point) of the groove is located on the q-axis side of the straight line B.

As a result, the magnetic flux waveform from the rotor 6 approaches a sine wave which is an ideal waveform shape, and harmonic components of the magnetic flux density in the stator are reduced, so that iron loss can be reduced and motor efficiency can be improved. it can. 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 narrowed, so the stress of the bridge portion 7 is not deteriorated.

Further, according to the rotor 6 of the rotating electrical machine of one embodiment, the electrical angle from the d-axis end of the groove 10 to the d-axis is θ1, and the rotation center is drawn from the rotation center to the outer periphery through the outermost periphery of the permanent magnet 2 When the straight line is a straight line C, the electrical angle from the straight line C to the d axis is θi, and the straight line drawn from the rotation center to the outer circumference through the outermost periphery of the permanent magnet 2 is a straight line When the electrical angle from D to d axis is θ0, the d-axis side end of the groove 10 is formed at a position satisfying (θi−θ0) / 3 + θ0 <θ1. As a result, the magnet flux contributing to the torque can be induced to the d-axis side more, and the primary component of the induced voltage can be increased, so that a larger torque can be obtained with a small current, and the motor loss can be reduced. it can.

Further, according to the rotor 6 of the rotating electrical machine of one embodiment, a plurality of notching points along the outer periphery of the rotor 6 cut at d-axis to q-axis at electrical angle intervals corresponding to one period of torque ripple harmonic component In this case, the d-axis side end of the groove is formed in a region from a position shifted by 1⁄5 cycle on the d-axis side with respect to the point E to a position shifted by 1⁄3 cycle on the q-axis side. As a result, the cogging torque can be reduced as compared with the reference example in which the groove is not formed, so that a motor with suppressed vibration and noise can be provided.

Further, according to the rotor 6 of the rotating electrical machine of one embodiment, when the order of the harmonic component of the torque ripple is n and the minimum integer satisfying m × (2π / n)> θ 0 is m, The d-axis side end portion is formed in a region from a position satisfying m × (2π / n) − (2π / n) / 5 to a position satisfying m × (2π / n) − (2π / n) / 3 Be done. By defining the position of the start point of the groove 10 in this manner, it is possible to achieve both a reduction in cogging torque and an improvement in torque, and to provide a motor with small motor loss, high efficiency, and reduced vibration. It becomes. In addition, by generalizing the position of the start point of the groove 10 having such an effect by an equation, it can be easily used for design.

Furthermore, according to the rotor 6 of the rotating electrical machine of one embodiment, the stator 20 further includes the stator 20 in which the rotor 6 is accommodated on the inner peripheral side, and the gap between the inner periphery of the stator 20 and the outer periphery of the rotor 6 Assuming that a distance of 21 is g, a line drawn from the rotation center of the rotor 6 through the deepest point on the rotation center side of the groove 10 to the virtual outer periphery of the rotor 6 is the distance from the deepest point to the virtual outer periphery When d is d, the groove 10 is formed to satisfy d ≦ 4 × g. Thereby, a motor with low cogging torque can be provided while reducing iron loss.

In the following, another modification provided with the feature according to the rotor 6 of the embodiment described above, that is, another modification including the groove 10 formed on the outer periphery of the rotor core 1 based on the above-described definition explain. Even with the rotor structure as described below, as long as the groove 10 having the above-described features is provided, the same technical effects as those described in the embodiment can be obtained.

(Modification 1)
FIG. 13 is a view for explaining the shape of the groove 10 according to the first modification. As illustrated, the shape of the groove 10 does not necessarily have to be formed in a triangular shape, and may be a rectangular shape as illustrated.

(Modification 2)
FIG. 14 is a view for explaining the shape of the groove 10 according to the second modification. As illustrated, 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 view for explaining the shape of the groove 10 according to the third modification. As illustrated, the shape of the groove 10 may be formed in a trapezoidal shape convex toward the rotation center side.

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

As mentioned above, although embodiment of this invention and its modification were described, the said embodiment and modification only showed a part of application example of this invention, and the technical scope of this invention It is not the meaning limited to a specific structure. For example, in the above description, the

air gaps

4 and 5 are described as being space portions, but they need not necessarily be spaces, and may be filled with a nonmagnetic material such as a resin material.

Further, the shapes of the

gaps

4 and 5 included in the above-described rotor 6 are not limited to the shapes described in FIG. 1 and the like, and may be appropriately changed. For example, the air gap 4 disclosed in FIG. 1 or the like is a strip formed substantially parallel to the q axis at the q axis end of the permanent magnet 2, but has a curved portion as shown in FIG. It may be. Even in this case, as illustrated, a line drawn to the outer periphery through the rotation center of the rotor and the d-axis side end of the air gap 4 is defined as a straight line A.

Claims

A plurality of magnetic poles are circumferentially disposed, each magnetic pole being configured by a pair of first permanent magnets disposed in a V-shape opening in the outer circumferential direction and a second permanent magnet disposed in the open portion of the V-shape A rotor of a rotating electrical machine,
In the magnet insertion hole into which the first permanent magnet is inserted, a first air gap provided continuously with the magnet insertion hole at an end portion on the q axis side orthogonal to the d axis formed by the one magnetic pole ,
A second air gap provided continuously with the magnet insertion hole at both ends of the magnet insertion hole into which the second permanent magnet is inserted;
And a groove formed along an axial direction of the rotor on an outer periphery of the rotor.
A straight line drawn through the rotation center of the rotor and the d-axis end of the first gap to the outer periphery is defined as a straight line A, and the rotation center and the q-axis end of the second gap When the straight line drawn to the outer periphery is straight line B, the q-axis side end of the groove is positioned on the straight line A, and the d-axis side end of the groove is positioned on the q axis side of the straight line B Do,
Rotor of rotating electric machine.
In a rotor of a rotating electrical machine according to claim 1,
Let the electrical angle from the d-axis end of the groove to the d-axis be θ 1,
Assuming that a straight line drawn from the center of rotation to the outer periphery through the outermost periphery of the first permanent magnet is a straight line C, an electrical angle from the straight line C to the d axis is θi
When a straight line drawn from the center of rotation to the outer periphery through the outermost periphery of the second permanent magnet is a straight line D, an electrical angle from the straight line D to the d-axis is θ0.
The d-axis side end of the groove is formed at a position satisfying (θi−θ0) / 3 + θ0 <θ1.
Rotor of rotating electric machine.
The rotor of the rotating electrical machine according to claim 1 or 2
In the case where a plurality of notching points obtained by cutting from the d axis to the q axis on the outer periphery of the rotor at electrical angle intervals corresponding to one period of the torque ripple harmonic component is taken as point E:
The d-axis side end of the groove is formed in a region from a position shifted by 1⁄5 cycle to the d-axis side with reference to the point E, to a position shifted by 1⁄3 cycle to the q-axis side.
Rotor of rotating electric machine.
In the rotor of the rotating electrical machine according to claim 2,
Let n be the order of the torque ripple harmonic component,
When m is a minimum integer that satisfies m × (2π / n)> θ 0, then
The d-axis side end of the groove is from a position satisfying m × (2π / n) − (2π / n) / 5 to a position satisfying m × (2π / n) − (2π / n) / 3 Formed in the area,
Rotor of rotating electric machine.
The rotor of the rotating electrical machine according to any one of claims 1 to 4
It further comprises a stator in which the rotor is accommodated on the inner circumferential side,
Let the gap distance between the inner circumference of the stator and the outer circumference of the rotor be g,
In a line drawn from the rotation center of the rotor through the deepest point on the rotation center side of the groove to the virtual outer periphery of the rotor core, the distance from the deepest point on the rotation center side to the virtual outer periphery is d If you
The groove is formed to satisfy d ≦ 4 × g.
Rotor of rotating electric machine.