JP6821022B2 - Rotor of rotating electric machine - Google Patents

Description

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

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

The IPM motor has a problem that the efficiency in a high rotation range is lowered due to the iron loss caused by the magnetic flux of the permanent magnet. It is also required to reduce the torque ripple in order to suppress the vibration and noise of the electric motor.

Further, from the viewpoint of ensuring the durability of the inverter parts, it is also necessary to prevent the peak value of the induced voltage from exceeding the withstand voltage of the inverter system. The induced voltage is a combination of the main component that contributes to torque and the harmonic component that does not contribute to torque. 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 increases. 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, in JP5516739B, a pair of permanent magnets arranged in a V shape that opens in the outer peripheral direction and a permanent magnet arranged in a V-shaped open portion, a total of three permanent magnets are used. A rotor structure has been proposed in which one magnetic pole is formed and a groove is formed on the outer periphery. According to the rotor structure proposed here, it is possible to provide a motor in which the cogging torque and the induced voltage are reduced while reducing the iron loss by forming the groove.

However, since the groove disclosed in JP5516739B only defines the center position on the outer circumference of the rotor, the effect of reducing iron loss can be sufficiently obtained depending on the circumferential width of the permanent magnet arranged on the outermost circumference. It has been found by the present inventors that there is a problem that the motor efficiency cannot 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 circumference of the rotor while considering the positional relationship with the permanent magnet arranged on the outermost circumference. The purpose is to provide a rotor that can.

The rotor of the rotary electric machine according to one aspect of the present invention is composed of a pair of first permanent magnets arranged in a V shape that opens in the outer peripheral direction and a second permanent magnet arranged in a V-shaped open portion. It is a rotor of a rotating electric machine in which a plurality of one magnetic poles are arranged in the circumferential direction, and in a magnet insertion hole into which a first permanent magnet is inserted, a q-axis side that is electrically orthogonal to the d-axis formed by the one magnetic pole. A first gap continuously provided with the magnet insertion hole at the end of the magnet, and a second gap continuously provided with the magnet insertion hole at both ends of the magnet insertion hole into which the second permanent magnet is inserted. , A groove formed along the axial direction of the rotor is provided on the 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 side end of the first gap is defined as a straight line A, and is drawn to the outer circumference through the rotation center and the q-axis side end of the second gap. When the straight line 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 the accompanying drawings.

FIG. 1 is a diagram for explaining a rotor structure of one embodiment. FIG. 2 is a diagram showing an analysis result of analyzing the iron loss reduction rate depending on the position of the start point of the groove. FIG. 3 is a diagram showing an analysis result of analyzing the change in stress of the bridge portion depending on the position of the start point of the groove. FIG. 4 is a diagram for explaining the analysis result of analyzing the magnetic flux density in the stator according to the outer peripheral shape of the rotor. FIG. 5 is a diagram showing analysis results of analysis of the ratio of motor loss between 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 diagram showing analysis results of analysis of changes in the primary component of the induced voltage depending on the position of the start point of the groove. FIG. 8 is a diagram for explaining the position of the starting point of the groove that contributes to the reduction of the cogging torque. FIG. 9 is a diagram showing an analysis result of analyzing a change in cogging torque depending on the position of a groove start point. FIG. 10 is a diagram showing an analysis result of analyzing changes in the primary components of the cogging torque and the induced voltage depending on the position of the starting point of the groove. FIG. 11 is a diagram for explaining the depth d of the groove. FIG. 12 is a diagram showing an analysis result of analyzing the iron loss reduction rate depending on the groove depth d. FIG. 13 is a diagram for explaining the groove of the modified example 1. FIG. 14 is a diagram for explaining the groove of the modified example 2. FIG. 15 is a diagram for explaining the groove of the modified example 3. FIG. 16 is a diagram for explaining the groove of the modified example 4. FIG. 17 is a diagram for explaining other modified examples. FIG. 18 is a diagram showing an analysis result of analyzing the ratio of loss of the conventional example to the reference example.

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

Although a rotor having an 8-pole structure is taken as an example here, the number of poles is not limited to this. However, the various analysis data described below are composed of a rotor 6 having an 8-pole structure and a stator (not shown) having a number of slots of 48 and a stator winding wound by distributed winding. It is premised that the present invention has been applied to the rotating electric machine and analyzed.

The rotor core (rotor core) 1 is formed in a cylindrical shape by a so-called laminated electromagnetic steel plate structure formed by laminating an electromagnetic steel plate having a thickness of several hundred μm in an annular shape in the axial direction. Further, in the rotor core 1, a magnet insertion hole 40 for embedding the permanent magnet 2 (hereinafter, also simply referred to as a magnet hole 40) and a magnet insertion hole 50 for embedding the permanent magnet 3 (hereinafter, also simply referred to as a magnet hole 50). Along with the formation of the magnet holes 40, voids 4 (first voids) are formed at both ends in the circumferential direction of the magnet holes 40, and voids 5 (second voids) are formed at both ends in the circumferential direction of the magnet holes 50. It is formed continuously.

The magnet holes 40 and 50 are holes formed by laminating a single sheet of electrical steel sheet in which a space for burying two permanent magnets 2 and one permanent magnet 3 is formed in the axial direction. is there.

In the magnet hole 40, the central portion in the circumferential direction and the portion located closest to the center of rotation is located on the d-axis, and both end portions in the circumferential direction move away from the d-axis and approach the q-axis and approach the outer circumference of the rotor, so-called. It is formed in a V shape.

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

As shown in the figure, since the magnet holes 40 have a shape that is line-symmetrical with respect to the d-axis, the pair of permanent magnets 2 also have a V-shaped arrangement that is line-symmetrical with respect to the d-axis and opens in the outer peripheral direction. Then, a pair of permanent magnets 2 arranged in the magnet hole 40 and a permanent magnet 3 arranged in the circumferential direction in the V-shaped open portion form a substantially triangular shape. In the rotor 6, one magnetic pole composed of the permanent magnet groups 30 arranged in such a substantially triangular shape is formed at each constant mechanical angle. Since the rotor 6 of the present embodiment has an octapole structure, permanent magnet groups 30 arranged in a substantially triangular shape are formed at every 45 degrees of mechanical angle. FIG. 1 shows one pole.

The permanent magnet group 30 is fixed in a state of being inserted into the corresponding positions 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 equidistant to each other and the polarities of the adjacent magnetic poles are different from each other along the circumferential direction of the rotor 6. Placed in. The direction of the magnetic flux generated by the permanent magnet group 30 is the d-axis (center of the magnetic pole), and the direction electrically and magnetically orthogonal to the d-axis is the q-axis.

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

Similarly, the permanent magnet 3 is formed to have a width in the longitudinal direction (circumferential direction) smaller than that of the magnet hole 50, and both ends in the circumferential direction of the magnet hole 50, in other words, a portion on the q-axis side of the permanent magnet 3. Is formed with a gap 5 as a space portion continuous with the magnet hole 50. These space portions have a lower magnetic permeability than an electromagnetic steel plate, that is, have a large magnetic resistance. Therefore, the voids 4 and 5 act as a magnetic barrier (flux barrier) through which the magnetic flux (flux) does not easily pass in the magnetic circuit in which the permanent magnet group 30 constitutes 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. Further, the groove 10 is 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, the tangent line drawn from the rotation center of the rotor core 1 through the tip of the gap 4 on the d-axis side to the outer periphery of the rotor core 1 is defined as the tangent line A, and the tangent line is defined as the tangent line A from the rotation center of the rotor core 1 to the q-axis side of the gap 5. When the tangent line drawn from the tip to the outer periphery of the rotor core 1 is defined as the tangent line B, the groove 10 has an end portion (start point) on the d-axis side and an end portion (end point) on the q-axis side in the circumferential width. Is formed so as 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 related to the groove 10 will be described later.

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

Here, before explaining the details of the groove 10, the conventional rotor structure and the characteristics and problems due to the structure will be described.

JP5516739B (conventional example) proposes a rotor structure in which a total of three permanent magnets are arranged in a substantially triangular shape to form one magnetic pole, and a groove is formed on the outer periphery of the rotor core. It is disclosed in the above document that the groove can exert an iron loss reducing effect by setting the groove center position. More specifically, the groove has a groove center position between the permanent magnet on the outermost peripheral side and the q-axis among a plurality of notches with an electric angle interval of one cycle of the harmonic component of the torque ripple. It is formed within the range of 1/4 cycle in the d-axis direction and 1/8 cycle in the q-axis direction with reference to the notch point in the region of. According to such a rotor structure, it is possible to provide a motor in which the cogging torque and the induced voltage are reduced while reducing the iron loss.

However, the inventors of the present invention can reduce iron loss at the groove center position based on the above characteristics, depending on the circumferential width of the permanent magnet on the outermost peripheral side of the three permanent magnets forming a substantially triangular shape. It was found that there is a problem that the motor efficiency cannot be improved because it cannot be sufficiently obtained.

FIG. 18 is a diagram showing an analysis result of analyzing the loss ratio [%] of the conventional example when the reference example having the same rotor structure as the conventional example is used as a reference except that the groove is not formed. .. FIG. 18A is a diagram showing the percentage of loss in the low load low speed region of the motor. FIG. 18B is a diagram showing the percentage of loss in the high load and high speed region of the motor. The figure shows that the loss of the conventional example is equivalent to that of the reference example without a groove, especially in the low load and low speed region that is constantly used in the vehicle drive motor, and the motor efficiency is improved even if the groove is formed. It shows that it has not been able to be made to.

The inventors of the present application have solved such a problem by expanding the shape of the groove in the circumferential direction and considering the positional relationship between the start point and the end point of the groove on the outer periphery of the rotor with the permanent magnets constituting the magnetic poles. We have found that it can be solved by specifying above. The 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. The electrical angle defined in the following description shall be defined in the region between the d-axis and one of the adjacent q-axis.

It has been mentioned above that the start and end points of the groove 10 are located within 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 electric angle from the start point to the d-axis, and the position of the end point is defined by θ2 which is the electric angle from the end point to the d-axis. To do.

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

FIG. 2 is a diagram showing an analysis result of analyzing the iron loss reduction rate depending on the position of the start point of the groove 10 when the above-mentioned reference example (without groove) is used as a reference (100%). The position of the starting point of the groove 10 is defined by θ1 which is an electric angle from the starting point to the d-axis (see FIG. 1). The vertical axis shows the iron loss reduction rate [%], and the horizontal axis shows θ1 [°]. Note that θ1 = 0 ° coincides with the d-axis. The dotted line drawn in the vicinity of θ1≈32 ° indicates θ0, which is the electrical angle from the outermost peripheral portion of the permanent magnet 3 on the q-axis side to the d-axis. Note that θ0 is defined as the electric angle from the straight line D to the d-axis when the straight line drawn from the center of rotation through the outermost peripheral portion of the permanent magnet 3 to the outer circumference of the rotor 6 is defined as the straight line D (FIG. 1). reference).

From FIG. 2, 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 on the q-axis side of the permanent magnet 3, in the region of θ1 <about 65 °. It can be seen that the iron loss is reduced. Further, the figure shows that the smaller θ1, that is, the closer the starting point is to the d-axis side, the more the iron loss is reduced. Therefore, it can be seen that the closer the start point of the groove 10 is to the d-axis side with θ1≈65 ° as the upper limit, the lower the motor loss and the more efficient the motor can be. Next, the lower limit of the starting point will be described with reference to FIG.

FIG. 3 is a diagram showing an analysis result of analyzing a change in stress of the bridge portion 7 depending on the position of the start point of the groove 10 when the above-mentioned reference example is used as a reference (reference value = 1). θ1≈44 ° coincides with the electrical angle from the tangent line B (see FIG. 1) drawn from the center of rotation to the outer periphery of the rotor 6 through the q-axis side end of the gap 5 to the d-axis. From the figure, when the start point of the groove 10 is formed at a position of θ1 <about 44 °, the smaller the θ1 is, that is, the more the start point is toward the d-axis side of the bridge portion 7, the more the bridge portion 7 is formed. It can be seen that the stress of is increasing. Therefore, the starting point of the groove 10 is set so as to be formed on the q-axis side of the bridge portion 7.

The bridge portion 7 is the thinnest portion in the surface direction of the rotor 6, and is the portion to which the most stress is applied when the permanent magnet 3 is held so as not to jump out to the outer periphery due to 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 thereof. In consideration of this, based on the analysis result shown in FIG. 3, the lower limit of the start point of the groove 10 is set on the q-axis side of the gap 5 on the q-axis side, thereby ensuring the strength of the bridge portion 7. 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 shall include a stator iron loss and a rotor iron loss.

FIG. 4 is a diagram for explaining the analysis result of analyzing the change in the magnetic flux density in the stator depending on the outer peripheral shape of the rotor 6. 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 shows the present embodiment, the alternate long and short dash line shows the conventional example, the alternate long and short dash line shows the reference example, and the dotted line shows the ideal waveform (sine wave). Further, 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 groove 10 of the present embodiment and the end point of the groove of the conventional example. There is.

As a premise, the magnetic flux waveform of the rotor having one magnetic pole formed by arranging three permanent magnets in a substantially triangular shape is the magnetic flux from the pair of permanent magnets 2 arranged in a V shape and the permanent magnets 3. Since it is a composite of magnet magnetic flux from, it contains a lot of harmonic components. If a groove is provided on the outer periphery of such a rotor, the magnetic resistance of the groove portion increases, so that the magnetic flux of the magnet interlinking from the groove portion to the stator side decreases. That is, by controlling the magnetic flux (rotor magnetic flux) from the rotor 6 by setting the circumferential width of the groove, it is possible to bring the magnetic flux waveform closer to a sine wave having an ideal waveform shape. By bringing the rotor magnetic flux closer to a sine wave, the harmonic component of the magnetic flux density in the stator is reduced as a result.

As shown in FIG. 4, the circumferential width of the groove 10 of the present embodiment is formed to be significantly wider than that of the conventional groove, so that the magnetic flux waveform approaches a more ideal sine wave as compared with the conventional example. You can see that. Further, by setting the position of the start point of the groove 10 on the d-axis side of the start point position of the conventional example L3, the magnetic flux waveform of the present embodiment can be at least closer to the ideal sine wave than the conventional example. Can be done.

FIG. 5 is a diagram showing an analysis result of analyzing the ratio [%] of the motor loss between the conventional example and the present embodiment when the reference example (without groove) is used as a reference (100%). FIG. 5A is a diagram showing the percentage of loss in the low load low speed region of the motor. FIG. 5B is a diagram showing the percentage of loss in the high load and 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 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 is brought closer to a sine wave and the harmonic component of the magnetic flux density in the stator is suppressed to suppress the harmonic component at high rotation. Iron loss can be significantly reduced.

That is, the rotor 6 of the present embodiment can reduce the iron loss by bringing the rotor magnetic flux closer to a sine wave by the groove 10, and as a result, not only the high addition high speed region but also FIG. 5A shows. 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 starting point of the groove 10 that 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 generated with a smaller current, and as a result, the motor loss can be reduced.

FIG. 6 is a diagram for explaining a starting point of the groove 10 defined from the viewpoint of improving torque performance. As described above, the position of the starting point is defined by the electrical angle θ1 from the d-axis. Further, the electric angle from the outermost peripheral portion 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 peripheral portion on the q-axis side of the permanent magnet 3 is defined as a straight line C, the electric angle from the straight line C to the d-axis is defined as θi.

On the premise of the above, the starting point of the groove 10 is formed so as to satisfy the following equation (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 analysis results of analysis of changes in the primary component of the induced voltage depending on the position of the start point of the groove 10. The horizontal axis shows the ratio [%] of the primary component of the induced voltage when θ1 [°] is used as a reference (100%) with reference to the reference example (without groove). The dotted line drawn at θ1≈32 ° indicates θ0, which is the electrical angle from the outermost peripheral portion of the permanent magnet 3 on the q-axis side to the d-axis, and the dotted line drawn at θ1≈78 ° is the permanent magnet 2. It shows θi which is an electric angle from the outermost peripheral portion of the above to the d-axis. The dotted line drawn at θ1≈47 ° in the figure indicates an electric angle satisfying the above equation (1) in the present embodiment. The primary component of the induced voltage shown in the figure is a fundamental wave of the induced voltage excluding the harmonic component.

Here, the torque of the IPM motor is a torque obtained by combining a magnet torque and a reluctance torque. The magnet torque increases in proportion to the magnitude of the primary component of the induced voltage generated by the magnetic flux of the magnet 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. By forming the start point of the groove 10 at a position satisfying the above equation (1), the magnetic flux of the magnet contributing to the torque can be induced toward the d-axis side, and the primary component of the induced voltage can be increased. Because there is. By setting θ1 so as to satisfy the above equation (1) in this way, a larger torque can be generated with a smaller current, so that the motor loss can be reduced.

The upper limit of θ1 may be set to an electric 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 for improving the torque performance as compared with the reference example. However, if the above-mentioned iron loss reduction effect is taken into consideration with reference to FIG. 2, θ1 ≈ 65 ° may be good, and therefore it may be appropriately set according to the purpose.

Next, the position of the starting point of the groove 10 that can effectively reduce the cogging torque will be described. The cogging torque is a positive or negative torque generated by the relative positional relationship between the stator and the rotor when the rotor rotates even when the rotor is not energized, and is a torque that causes vibration and noise of the motor.

FIG. 8 is a diagram for explaining the position of the starting point of the groove 10 that contributes to the reduction of the cogging torque. In the upper part of the figure, the harmonic component of the torque ripple corresponding to the outer peripheral shape of the rotor 6 shown in the lower part of the figure is shown corresponding to the electric angle [°] starting from the d-axis.

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 in which the cogging torque can be lowered as compared with the reference example in which the groove is not formed. Is defined as. Here, as described in the upper part of FIG. 8, a plurality of notches on the outer circumference of the rotor 6 at intervals of one cycle of the harmonic component of the torque ripple from the d-axis to the q-axis are defined as points E. In this case, the start point of the groove 10 of the present embodiment is formed in a region from a position shifted by 1/5 cycle to the d-axis side to a position shifted by 1/3 cycle to the q-axis side with respect to the point E ( See the double-headed arrow in the figure). The cogging torque reduction effect when the groove 10 is formed in this way will be described with reference to FIG.

FIG. 9 is a diagram showing an analysis result of analyzing a change in cogging torque depending on the position of a start point of the groove 10. The upper part of the figure shows the ratio [%] of the cogging torque according to θ1 that defines the position of the start point of the groove 10 when the reference example (without groove) is used 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 defining the position of the start point of the groove 10, is shown according to θ1 [°].

As shown in the figure, when the start point of the groove 10 is formed in the region from the position shifted by 1/5 cycle to the d-axis side to the position shifted by 1/3 cycle to the q-axis side with respect to the point E, the groove is formed. 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 as compared with the reference example.

Further, in consideration of the above equation (1), 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 of analyzing changes in the primary components of the cogging torque and the induced voltage depending on the position of the start point of the groove 10. FIG. 10 is a diagram in which changes in the induced voltage primary component according to the start point position of the groove 10 described with reference to FIG. 7 are superimposed and displayed on FIG. 9 above. The line drawn in the vicinity of θ1≈47 ° shown in the figure is an electric angle satisfying (θi−θ0) / 3 + θ0 represented by the above equation (1).

As shown in the figure, when the start point of the groove 10 is formed in the region from the position shifted by 1/5 cycle to the d-axis side to the position shifted by 1/3 cycle to the q-axis side with respect to the point E, the groove is formed. 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 a decrease in cogging torque and an improvement in torque, (θi−θ0) / 3 + θ0 <θ1 represented by the above equation (1) is taken into consideration, and the point E in the vicinity of θ1≈60 ° is used as a reference. As a result, it can be seen that it is more preferable to form the start point of the groove 10 in the region from the position shifted by 1/5 cycle to the d-axis side to the position shifted by 1/3 cycle to the q-axis side. By defining the position of the starting point of the groove 10 in this way, it is possible to provide a motor in which the cogging torque is reduced and the torque is improved, the motor loss is small, the efficiency is high, and the vibration is reduced. It becomes.

Next, the position of the starting point of the groove 10 described with reference to FIG. 10 is expressed by an equation. By generalizing by the formula, it can be easily used in the design. That is, when the order of the harmonic component of the torque ripple is n and the electrical angle from the outermost peripheral portion 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 is m, the starting point of the groove 10 is formed in the range from the position satisfying the following equation (2) to the position satisfying the following equation (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, both a decrease in cogging torque and an improvement in torque are achieved, and the motor loss is small and high. It is possible to provide a motor that is efficient and has reduced 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 on the rotation center side to the virtual outer circumference on the line F drawn from the rotation center of the rotor 6 to the virtual outer circumference of the rotor 6 through the deepest point on the rotation center side of the groove. Is defined as the distance of.

Further, 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 circumference of the stator 20 and the outer circumference of the rotor 6. In this case, the depth d of the groove 10 is formed so as to satisfy d ≦ 4 × g.

FIG. 12 is a diagram showing an analysis result of analyzing the iron loss reduction rate due to the depth d of the groove 10 when the reference example (without groove) is used as a reference (iron loss reduction rate: 100%, cogging torque: 1). Is. 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, by setting the depth d of the groove 10 to d ≦ 4 × g as described above, it is possible to provide a motor having a low cogging torque while reducing iron loss. If the depth d of the groove 10 is d> 4 × g, the iron loss gradually increases, which is not preferable. This is because the deeper the groove 10 is, the more the magnetic flux waveform of the present embodiment shown in FIG. 4 deviates from the ideal sinusoidal system.

As described above, the rotor (rotor 6) of the rotary electric machine of the present embodiment is arranged in a pair of first permanent magnets (permanent magnets 2) arranged in a V shape that opens in the outer peripheral direction and a V-shaped open portion. It is a rotor 6 of a rotary electric machine in which a plurality of one magnetic poles composed of the second permanent magnet (permanent magnet 3) are arranged in the circumferential direction, and one magnetic pole is inserted in a magnet insertion hole 40 into which the permanent magnet 2 is inserted. A first gap (gap 4) continuously provided with a magnet insertion hole 40 at an end on the q-axis side electrically orthogonal to the d-axis formed by the magnet 3 and a magnet insertion hole 50 into which the permanent magnet 3 is inserted. A second gap (gap 5) continuous with the magnet insertion hole 50 is provided at both ends, and a groove 10 formed along the axial direction of the rotor 6 is provided on the outer periphery of the rotor 6. 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 gap 4 is defined as a straight line A, and a straight line drawn to the outer circumference 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.

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

Further, according to the rotor 6 of the rotary electric machine of one embodiment, the electric angle from the d-axis side end of the groove 10 to the d-axis is set to θ1, and the groove 10 is pulled from the center of rotation through the outermost peripheral portion of the permanent magnet 2 to the outer circumference. When the straight line is a straight line C, the electric angle from the straight line C to the d-axis is θi, and the straight line drawn from the center of rotation through the outermost peripheral portion of the permanent magnet 2 to the outer circumference is a straight line D. When the electric angle from the D to the 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 magnetic flux of the magnet that contributes to the torque can be induced toward the d-axis side, and the primary component of the induced voltage can be increased. Therefore, a larger torque can be generated with a smaller current, and the motor loss can be reduced. it can.

Further, according to the rotor 6 of the rotary electric machine of one embodiment, a plurality of notches on the outer circumference of the rotor 6 in which the d-axis to the q-axis are carved at an electrical angle interval of one cycle of the harmonic component of the torque ripple are designated as points E. In this case, 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 to a position shifted by 1/3 cycle to the q-axis side with respect to the point E. As a result, the cogging torque can be reduced as compared with the reference example in which the groove is not formed, so that it is possible to provide a motor in which vibration and noise are suppressed.

Further, according to the rotor 6 of the rotary electric machine of one embodiment, when the order of the harmonic component of the torque ripple is n and the smallest integer satisfying m × (2π / n)> θ0 is m, the groove 10 is formed. The d-axis side end is formed in the region from the position satisfying m × (2π / n) − (2π / n) / 5 to the position satisfying m × (2π / n) − (2π / n) / 3. Will be done. By defining the position of the starting point of the groove 10 in this way, it is possible to provide a motor in which the cogging torque is reduced and the torque is improved, the motor loss is small, the efficiency is high, and the vibration is reduced. It becomes. Further, by generalizing the position of the starting point of the groove 10 having such an effect by an equation, it can be easily used in the design.

Further, according to the rotor 6 of the rotary electric machine of one embodiment, a stator (stator) 20 for accommodating the rotor 6 is further provided on the inner peripheral side, and a gap between the inner circumference of the stator 20 and the outer circumference of the rotor 6 is provided. Let g be the distance of 21, and the distance from the deepest point on the rotation center side to the virtual outer circumference in the line drawn from the rotation center of the rotor 6 to the virtual outer circumference of the rotor 6 through the deepest point on the rotation center side of the groove 10. When d is, the groove 10 is formed so as to satisfy d ≦ 4 × g. This makes it possible to provide a motor having a low cogging torque while reducing iron loss.

In the following, another modification having the characteristics related to the rotor 6 of one embodiment described so far, that is, another modification having a groove 10 formed on the outer circumference of the rotor core 1 based on the above-mentioned regulations will be described. explain. Even with the rotor structure as described below, as long as the groove 10 having the above characteristics is provided, the same technical effect as described in one embodiment can be obtained.

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

(Modification 2)
FIG. 14 is a diagram for explaining the shape of the groove 10 according to the second modification. As shown in the figure, the shape of the groove 10 may be formed into an arc shape that is convex toward the center of rotation.

(Modification 3)
FIG. 15 is a diagram for explaining the shape of the groove 10 according to the modified example 3. As shown in the figure, the shape of the groove 10 may be formed into a trapezoidal shape that is convex toward the center of rotation.

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

Although the embodiments of the present invention and the modifications thereof have been described above, the above-described embodiments and modifications show only a part of the application examples of the present invention, and the technical scope of the present invention is defined in the above-described embodiments. It is not intended to be limited to a specific configuration. For example, in the above description, the voids 4 and 5 are described as space portions, but they do not necessarily have to be spaces, and may be filled with a non-magnetic material such as a resin material.

Further, the shapes of the gaps 4 and 5 provided in the rotor 6 are not limited to the shapes shown in FIG. 1 and may be changed as appropriate. For example, the void 4 disclosed in FIG. 1 and the like has a band shape formed substantially parallel to the q axis at the end portion of the permanent magnet 2 on the q axis side, but has a curved portion as shown in FIG. There may be. Even in this case, as shown in the drawing, the line drawn to the outer circumference through the rotation center of the rotor and the d-axis side end of the gap 4 is defined as the straight line A.

Claims (5)

A plurality of single magnetic poles composed of a pair of first permanent magnets arranged in a V shape that opens in the outer peripheral direction and a second permanent magnet arranged in the open portion of the V shape are arranged in the circumferential direction. It is a rotor of a rotating electric machine,
In the magnet insertion hole into which the first permanent magnet is inserted, a first void provided continuously with the magnet insertion hole at an end on the q-axis side electrically orthogonal to the d-axis formed by the one magnetic pole. ,
Second voids provided at both ends of the magnet insertion hole into which the second permanent magnet is inserted, which are continuous with the magnet insertion hole,
A groove formed along the axial direction of the rotor is provided on the outer periphery of the rotor.
A straight line drawn to the outer periphery through the rotation center of the rotor and the d-axis side end of the first gap is defined as a straight line A, and passes through the rotation center and the q-axis side end of the second gap. When the straight line drawn to the outer circumference 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. To do,
Rotor of rotating electric machine. In the rotor of the rotary electric machine according to claim 1,
The electric angle from the d-axis side end of the groove to the d-axis is set to θ1.
When a straight line drawn from the center of rotation through the outermost peripheral portion of the first permanent magnet to the outer circumference is defined as a straight line C, the electric angle from the straight line C to the d-axis is defined as θi.
When a straight line drawn from the center of rotation through the outermost peripheral portion of the second permanent magnet to the outer circumference is defined as a straight line D, and when the electric 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. In the rotor of the rotary electric machine according to claim 1 or 2.
When a plurality of notches on the outer circumference of the rotor from the d-axis to the q-axis are carved at an electrical angle interval equivalent to one cycle of the harmonic component of the torque ripple, as a 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 to a position shifted by 1/3 cycle to the q-axis side with respect to the point E.
Rotor of rotating electric machine. In the rotor of the rotary electric machine according to claim 2,
Let n be the order of the harmonic components of the torque ripple.
When m is the smallest integer that satisfies m × (2π / n)> θ0,
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. In the rotor of the rotary electric machine according to any one of claims 1 to 4.
Further provided with a stator on the inner peripheral side for accommodating the rotor,
Let g be the gap distance between the inner circumference of the stator and the outer circumference of the rotor.
In the line drawn from the rotation center of the rotor to the virtual outer circumference of the rotor core through the deepest point on the rotation center side of the groove, the distance from the deepest point on the rotation center side to the virtual outer circumference is d. When
The groove is formed so as to satisfy d ≦ 4 × g.
Rotor of rotating electric machine.

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