JP6857959B2 - Rotor structure for magnet-embedded motor and motor with this structure - Google Patents

Description

The present invention relates to a rotor structure for a magnet-embedded motor in which a plurality of permanent magnets are embedded in a peripheral portion of a rotor core formed by laminating a large number of rotor core plates in the axial direction, and a motor provided with this structure.

Even if the rotor of the motor with the magnet embedded in the rotor rotates at high speed, there is no risk that the magnet will come off or scatter, but the stator and magnet of the rotor arranged outside the rotor There arises a problem that the distance becomes large, the magnetic force becomes weak, and the torque of the rotor decreases. Therefore, a magnet-embedded motor that can increase the obtained torque by devising the shape of the rotor core plate for embedding the rotor magnet and using not only the magnet torque of the magnet but also the reluctance torque due to the magnetic field lines has been proposed. (See Patent Document 1).

The rotor core plate described in Patent Document 1 is composed of fan-shaped thin plates obtained by dividing a disc made of a ferromagnetic material into a plurality of pieces in the circumferential direction, laminated in the rotation axis direction, and connecting the thin plates in the circumferential direction. ing. Inside the thin plate, two holes for inserting permanent magnets are provided.

A pair of holes are formed so as to extend linearly from the central portion in the circumferential direction of the peripheral portion of the thin plate formed in a fan shape to both sides of the thin plate. These holes are configured to have a rectangular hole portion formed inside the peripheral edge portion of the thin plate and a rectangular elongated hole portion connected to the rectangular hole portion and extending to the side portion of the thin plate. A magnet is inserted into the elongated hole. The holes communicate with holes formed in other thin plates adjacent to each other in the circumferential direction to form a pair, and magnets are inserted into each of the two holes in the pair with their poles aligned.

When the rotor of the motor configured in this way rotates, the magnetic flux generated by the q-axis current of the stator arranged so as to surround the rotor attracts the rotor, and a relaxation torque is generated to rotate the rotor. The torque for this can be increased. The magnetic flux line due to the q-axis current that generates the reluctance torque passes through the thin plate between the pair of holes having a small reluctance, and the higher the density of the magnetic flux line, the larger the reluctance torque.

Japanese Unexamined Patent Publication No. 2012-205446

However, since the rectangular hole portion formed in the thin plate of the rotor described in Patent Document 1 extends linearly in the rotor radial direction, a part of the magnetic flux line due to the q-axis current is formed by the rectangular hole portion. There is a risk that the magnetic flux density of the magnetic flux lines will decrease due to the interruption, and the reluctance torque will decrease.

On the other hand, since the price of rare earth magnets has been soaring in recent years, the cost of the motor increases in the rotor in which a large number of magnets described in Patent Document 1 are used. Therefore, if the number of magnets is reduced, the cost increase of the motor can be suppressed, but if the number of magnets is easily reduced, the torque of the motor is reduced and a desired torque cannot be obtained.

In view of the above circumstances, at least some embodiments of the present invention provide a rotor structure for a magnet-embedded motor and this structure, which does not cause a decrease in the torque of the motor even if the number of magnets embedded in the rotor is reduced. It is an object of the present invention to provide a motor to be provided.

The rotor structure for a magnet-embedded motor according to at least one embodiment of the present invention.
A rotor structure for a magnet-embedded motor in which a plurality of permanent magnets are embedded in the periphery of a rotor core formed by laminating a large number of rotor core plates in the axial direction.
The rotor core plate is
A magnet mounting hole that extends along the circumferential direction and is provided at equal intervals on the outer peripheral portion of the rotor core plate and penetrates in the axial direction of the rotor core plate.
A salient pole portion integrally formed with the rotor core plate on the outer peripheral portion of the rotor core plate on the radial outer side of each of the plurality of magnet mounting holes.
The permanent magnet, which is housed in a state of being fixed to each of the plurality of magnet mounting holes,
A bridge portion formed in a spatial region between the salient poles adjacent to the rotor core plate in the circumferential direction and connecting the radial outer ends of the salient poles adjacent to the circumferential direction, the circumferential direction of the bridge. It is formed on both sides of the support column portion, which extends from the intermediate portion toward the axial center side of the rotor core plate and is surrounded by a support column portion integrally formed with the rotor core plate and end faces of permanent magnets adjacent in the circumferential direction. Formed with a pair of holes,
The portion of the bridge portion forming the hole portion connected to the magnet mounting hole is the central axis (d-axis) of the permanent magnet accommodated in the magnet mounting hole when the rotor core plate is viewed from the axial direction. ) Is an acute angle with respect to the virtual line orthogonal to the radial side of the rotor core plate, and is curved so as to decrease toward the radial side of the rotor core plate.
The portion of the bridge portion forming the hole portion, which is connected to the strut portion side, is configured to be curved toward the permanent magnet side adjacent to the hole portion as it advances outward in the radial direction of the rotor core plate. ..

According to the above-mentioned rotor structure for a magnet-embedded motor, the portion of the bridge portion connected to the magnet mounting hole is a virtual line orthogonal to the central axis (d-axis) of the permanent magnet when the rotor core plate is viewed from the axial direction. On the other hand, the angle at which the rotor core plate is inclined outward in the radial direction is an acute angle and is curved so as to become smaller as it approaches the bridge portion. Therefore, as compared with the case where the portion of the bridge portion connected to the magnet mounting hole extends linearly in the radial direction, the region between the portion of the bridge portion connected to the magnet mounting hole and the peripheral portion of the rotor core plate is reduced. Can be wide. Therefore, it is possible to reduce the number of magnetic flux lines in which a part of the magnetic flux lines in the q-axis direction formed by the coil of the stator is blocked by the holes, and it is possible to suppress a decrease in the magnetic flux density of the magnetic flux lines passing through the salient pole portion. Therefore, the reluctance torque due to the magnetic flux line in the q-axis direction created by the coil of the stator can be increased. Therefore, even if the number of permanent magnets provided in the rotor is reduced, it is possible to prevent the torque of the motor from decreasing. Therefore, it is possible to provide a rotor structure for a magnet-embedded motor that does not cause a decrease in the torque of the motor even if the number of magnets is reduced in order to suppress an increase in the cost of the motor. In addition, when the rotor rotates at high speed, centrifugal force acting outward in the radial direction of the rotor acts on the bridge, causing stress in the bridge, but the part of the bridge that forms the hole that is connected to the magnet mounting hole. The portion connected to the support column side is curved. Therefore, it is possible to eliminate the possibility of stress concentration occurring in these portions, and it is possible to suppress damage to the bridge portion.

Also, at least some embodiments of the present invention
The strut portion is configured to extend toward the axial direction of the rotor core plate.

In this case, since the strut portion extends toward the axial center of the rotor core plate, the centrifugal force acting on the bridge portion via the strut portion during the rotation of the rotor is stressed toward the axial center side of the rotor core plate. Can be supported. Therefore, since the centrifugal force acting on the bridge portion is surely supported, the risk of damage to the bridge portion can be further reduced when the rotor is rotated.

Also, at least some embodiments of the present invention
The pair of holes are formed symmetrically in the circumferential direction of the rotor core plate with the support column as the center.

In this case, since the pair of holes are symmetrically formed in the circumferential direction of the rotor core plate with the support column as the center, the stress generated in the bridge forming the pair of holes when the rotor rotates is also symmetrical. Occurs. Therefore, it is possible to prevent the possibility that an unbalanced stress is generated in the bridge portion forming the hole portion, and it is possible to further reduce the possibility that the bridge portion is damaged.

Further, the magnet-embedded motor according to at least one embodiment of the present invention is a motor.
A motor case that rotatably supports the magnet-embedded motor rotor according to any one of claims 1 to 3.
The inner surface of the motor case is configured to include a stator that is fixed to the outer peripheral surface of the magnet-embedded motor rotor with a predetermined air gap.

According to the magnet-embedded motor, the inner surface of the motor case that rotatably supports the rotor having the magnet-embedded motor rotor structure according to any one of claims 1 to 3 with respect to the outer peripheral surface of the rotor. A motor having a rotor structure for a magnet-embedded motor that does not cause a decrease in the torque of the motor even if the number of magnets is reduced in order to suppress an increase in the cost of the motor by providing a stator that is fixed with a predetermined air gap. Can be realized.

According to at least some embodiments of the present invention, a rotor structure for a magnet-embedded motor that does not cause a decrease in the torque of the motor even if the number of magnets is reduced in order to suppress an increase in the cost of the motor, and a motor having this structure. Can be provided.

It is sectional drawing of the motor which has the rotor core plate which comprises the rotor structure for the magnet embedded type motor which concerns on this invention, and the stator surrounding the rotor core plate. It is a partially enlarged view of the periphery of the peripheral edge portion of the rotor core plate shown in FIG. It is a cross section of a motor showing the magnetic flux density distribution of the magnetic flux lines created by the q-axis current of the armature of the stator. It is sectional drawing of the motor which showed the magnetic flux density distribution of the magnetic flux line which a permanent magnet makes when the stator current is zero. It is sectional drawing of the motor which showed the magnetic flux density distribution of the magnetic flux line when the width of the support column part is narrow. It is sectional drawing of the motor which showed the magnetic flux density distribution of the magnetic flux line when the width of the support column part is wide. It is a graph which shows the relationship of the torque, the torque ripple, and the terminal voltage of a motor with respect to the width of a strut part. It is a graph which shows the relationship of the torque of the motor, the torque ripple, and the terminal voltage with respect to the rise angle θ of the part of the bridge part which forms a hole, which is connected to a magnet mounting hole. It is a graph which shows the relationship of the torque of the motor, the torque ripple, and the terminal voltage with respect to the depth of a hole. It is a graph which shows the relationship between the linear-axis inductance Ld and the horizontal-axis inductance Lq of a motor with respect to the phase φ of a stator current. It is a graph which shows the relationship between the linear-axis inductance Ld and the horizontal-axis inductance Lq with respect to the amplitude Im of the stator current.

Hereinafter, embodiments of the present invention will be described with reference to FIGS. 1 to 11 with reference to the accompanying drawings. The motor of this embodiment will be described below by taking a 9-slot 6-pole type as an example. However, the dimensions, materials, shapes, relative arrangements, and the like of the components described in this embodiment are not intended to limit the scope of the present invention to that alone unless otherwise specified.

FIG. 1 is a cross-sectional view of a motor including a rotor structure for a magnet-embedded motor. As shown in FIG. 1, the motor 1 includes a rotor core 10 rotatably supported and a stator 50 arranged so as to surround the rotor core 10. The rotor core 10 is formed by laminating a large number of rotor core plates 11 formed in a disk shape in the axial direction. The rotor core plate 11 is made of a soft magnetic material. The soft magnetic material may be made of any material, but is preferably an iron-based material such as silicon steel, pure iron, or alloy steel.

An insertion hole 11a into which the rotating shaft 12 is inserted is provided in the central portion of the rotor core plate 11, and a magnet mounting hole 11b for inserting the permanent magnet 13 is provided in the circumferential direction in the circumferential portion of the rotor core plate 11. A plurality of magnets are provided at equal intervals. The magnet mounting hole 11b is formed in a rectangular shape extending linearly in the circumferential direction on the outer peripheral portion of the rotor core plate 11. In the present embodiment, the magnet mounting holes 11b are provided at an angle of 60 degrees with respect to other magnet mounting holes 11b adjacent in the circumferential direction.

When a large number of rotor core plates 11 are laminated in the axial direction, the magnet mounting holes 11b formed in each of the rotor core plates 11 communicate with each other. A permanent magnet 13 having an N pole on one side in the radial direction and an S pole on the other side of the rotor core 10 is inserted into the communicating magnet mounting hole 11b. The permanent magnets 13 mounted on the magnet mounting holes 11b adjacent to each other in the circumferential direction are inserted so that the poles are arranged in opposite directions.

A salient pole portion 11c integrally formed with the rotor core plate 11 is formed on the radial outer side of the magnet mounting hole 11b. As shown in FIG. 2, the salient pole portion 11c has an outer edge portion formed in an arc shape. The outer edge portion of the salient pole portion 11c has a radius Ra (Ra <, which is smaller than the radius Rb having a distance between the point P at which the outer edge portion intersects the d-axis of the permanent magnet 13 and the axis S of the rotor core plate 11. It has Rb) and is formed in an arc shape with the stator 50 side of the d-axis convex. The center S'of the radius Ra is provided on the line La connecting the point P and the axis S. Further, the outer diameter of the rotor core 10 drawn by the radius Rb is hereinafter referred to as “rotor outer diameter”. FIG. 2 shows a case where the shortest distance between the permanent magnets 13 adjacent to each other in the circumferential direction (distance between the two inner corners of the four corners between the permanent magnets 13 in the rotor radial direction) dm is 0.634 with respect to the magnet length Lm. Shown.

Here, when the magnetic force f of the armature 51 of the stator 50 attracts the permanent magnet 13 of the rotor core 10, the rotational direction component f _θ of the rotor core 10 of the magnetic force f produces a rotational torque. In this magnetic force f, the interaction between the magnetic flux generated by the current flowing through the coil of the armature 51 of the stator 50 (hereinafter referred to as “stator current”) and the magnetic flux of the permanent magnet 13 that changes depending on the rotation angle of the rotor core 10 is constant. Therefore, the motor 1 is caused to vibrate (torque ripple). This torque ripple increases as the radial component fr of the magnetic force that rotates the rotor core 10 increases, and decreases as _{the rotational component f θ of the magnetic force increases.} On the other hand, the rotational torque increases as _{the rotational direction component f θ of the magnetic force increases.}

Therefore, the shape of the outer edge portion of the salient pole section 11c is not a circular arc having a curvature radius Rb, as the rotational direction component f _theta of the magnetic force is increased, had a curvature radius smaller Ra than the radius Rb It is formed in an arc shape.

A space region ts is formed between the salient poles 11c adjacent to the rotor core plate 11 in the circumferential direction. In this space region ts, a bridge portion 15 connecting the radial outer ends of the salient pole portions 11c adjacent to each other in the circumferential direction and an intermediate portion in the circumferential direction of the bridge portion 15 extend toward the axial center of the rotor core plate 11. A support column 17 integrally formed with the rotor core plate 11 is provided. A pair of holes 19 surrounded by the end faces of the bridge portion 15, the strut portion 17, and the permanent magnets 13 adjacent in the circumferential direction are formed on both sides of the strut portion 17.

The strut portion 17 extends toward the axial center S direction side of the rotor core plate 11, and is formed in a T shape by the bridge portion 15 and the strut portion 17. Further, the pair of hole portions 19 are formed symmetrically in the circumferential direction of the rotor core plate 11 with the strut portion 17 as the center.

Further, the magnet side portion 15a connected to the magnet mounting hole 11b of the bridge portion 15 forming the hole portion 19 is a permanent magnet 13 housed in the magnet mounting hole 11b when the rotor core plate 11 is viewed from the axial direction. The angle θ that inclines outward in the radial direction of the rotor core plate 11 with respect to the virtual line Lb orthogonal to the central axis 13a (d axis) is an acute angle and is curved so as to become smaller as it approaches the bridge portion 15.

Further, of the bridge portion 15 forming the hole portion 19, the strut side portion 15b connected to the strut portion side is curved toward the permanent magnet 13 side adjacent to the hole portion 19 as it advances radially outward of the rotor core plate 11. .. The width b of the strut portion 17 may have a size capable of supporting the centrifugal force acting on the bridge portion 15 when the rotor core 10 rotates. The details of the shape of the bridge portion 15 will be described later.

As shown in FIG. 1, the rotor core 10 configured in this way is rotatably supported in a cylindrically formed motor case 60 via a rotating shaft 12 mounted on the rotor core 10.

On the other hand, the stator 50 is mounted on the inner surface of the motor case 60 and is fixed to the outer peripheral surface of the rotor core 10 with an air gap g. As described above, in the rotor core 10, a plurality of salient pole portions 11c having a radius Ra smaller than the rotor outer diameter Rb and being formed in a convex shape are continuously formed in the circumferential direction according to the number of poles ( 6 in this embodiment). Therefore, on the outer circumference of the rotor core 10, the region As indicated by the diagonal line surrounded by the outer circumference of the pair of salient poles 11c adjacent to each other in the circumferential direction and the q-axis extending on both sides of the pair of salient poles 11c is the ginkgo tree. It has a leaf-like shape. Therefore, as shown in FIGS. 1 and 2, the air gap g between the inner surface of the stator 50, that is, the inner peripheral surface 51a of the armature 51 and the outer peripheral surface 10a of the rotor core 10 is electrically orthogonal to the d-axis. It is formed so as to be wide on the q-axis and narrow on the d-axis.

A plurality of armatures 51 (nine in the present embodiment) that perform field magnetization in a winding type are arranged on the stator 50 at predetermined intervals in the circumferential direction of the stator 50. A three-phase alternating current flows through the coil 51b of the armature 51 via an inverter. As a result, a rotating magnetic field is generated between the armature 51 of the stator 50 and the permanent magnet 13 of the rotor core 10. The rotor core 10 rotates due to the magnet torque generated by this rotating magnetic field and the reluctance torque described later. Details of the magnet torque and reluctance torque will be described later.

As shown in FIG. 3, a magnetic flux φq due to a q-axis current passes through the rotor core 10 configured in this way as a stator current. The magnetic flux φq extends in an arc shape from one side in the circumferential direction of the salient pole portion 11c having a small magnetic resistance to the other side at right angles to the central axis (d axis) of the permanent magnet 13 of the rotor core 10. The magnetic flux lines of the magnetic flux φq act as if the stretched rubber shrinks, causing the rotor core 10 to rotate in the counterclockwise direction (arrow A direction). Of the forces of the magnetic field lines, the tangential component of the rotor core plate 11 becomes the reluctance torque that rotates the rotor core 10 in the counterclockwise direction.

Further, the rotor core 10 generates magnet torque due to the attractive force and the repulsive force between the permanent magnet 13 in the rotor core 10 and the armature 51 of the stator 50. FIG. 4 shows the magnetic field lines created by the permanent magnet 13 when the stator current is set to zero. In the support column 17, as shown in FIG. 4, the lines of magnetic force extend in the direction orthogonal to the radial direction and pass through the hole 19. Since the hole 19 has a large magnetic resistance, there are few lines of magnetic force passing through the support column 17. When the rotor core 10 is actually rotated, the lines of magnetic force shown in FIG. 3 and the lines of magnetic force shown in FIG. 4 are superposed (see FIG. 5). As shown in FIG. 5, the rotor core 10 is rotated counterclockwise (in the direction of arrow A) by a force that tries to restore the strain of the magnetic field lines.

Here, as shown in FIG. 2, the support column portion 17 extends toward the axial center S direction of the rotor core plate 11. When the rotor core 10 rotates, a centrifugal force acts on the bridge portion 15, and this centrifugal force is transmitted to the rotor core plate 11 via the strut portion 17 connected to the bridge portion 15. Therefore, the bridge portion 15 is reliably supported via the support column portion 17, and the risk of damage to the bridge portion 15 during rotation of the rotor core 10 can be reduced.

As shown in FIGS. 2 and 3, the width b of the strut portion 17 (the circumferential length of the rotor core plate 11) has a size capable of supporting the centrifugal force acting on the bridge portion 15 when the rotor core 10 rotates. I just need to be there. However, when this width b is increased, a part of the magnetic flux due to the q-axis current of the stator 50 passes through the strut portion 17 and the magnetic flux density of the magnetic flux passing through the salient pole portion 11c decreases. Therefore, it is preferable that the width b of the strut portion 17 has a size capable of supporting centrifugal force and the magnetic flux density of the magnetic flux passing through the salient pole portion 11c does not decrease.

FIG. 5 is a cross-sectional view of the motor 1 showing the distribution of magnetic flux lines when the width b of the strut portion 17 is narrow (width b / magnet length Lm = 0.267), and FIG. 6 is a cross-sectional view of the strut portion 17. Is a cross-sectional view of the motor 1 showing the distribution of magnetic flux lines when is wide (width b / magnet length Lm = 0.6). The magnet length Lm refers to the circumferential length of the permanent magnet 13. The density of the magnetic flux lines phi _S for q-axis current makes passing between the permanent magnet 13 and the armature 51 shown in FIG. 5, q axis current makes passing between the permanent magnet 13 and the armature 51 shown in FIG. 6 It can be seen that it is larger than the density of the magnetic flux lines φ _L. Therefore, the width b of the strut portion 17 is preferably narrow (width b / magnet length Lm = 0.267). The magnetic flux lines shown in FIGS. 5 and 6 show the results of the magnetic flux distribution when the effective value of the stator current is 78A and the current phase is 20 degrees.

Here, the magnetic flux phi _S for q-axis current and the permanent magnet 13 is made, as shown in FIG. 5, but extends to be inclined to the permanent magnet 13 side as going from one circumferential direction of the salient pole section 11c to the other side A pair of holes 19 having the same magnetic resistance as the permanent magnet 13 are formed on both sides of the salient pole portion 11c in the circumferential direction. The hole 19 may reduce the magnetic flux density of the magnetic flux passing through the salient pole 11c. As shown in FIG. 2, the hole 19 includes a bridge portion 15 connecting the radial outer ends of the salient poles 11c adjacent to each other in the circumferential direction, and a rotor core plate 11 from the circumferential intermediate portion of the bridge portion 15. It is formed by being surrounded by a support column 17 extending toward the axis side of the rotor core plate 11 and integrally formed with the rotor core plate 11 and end faces of permanent magnets 13 adjacent to each other in the circumferential direction.

Of the bridge portions 15 forming the hole portion 19, the magnet side portion 15a connected to the magnet mounting hole is the central axis of the permanent magnet 13 housed in the magnet mounting hole 11b when the rotor core plate is viewed from the axial direction. The angle θ that inclines outward in the radial direction of the rotor core plate 11 with respect to the virtual line Lb orthogonal to the d-axis) is an acute angle and is curved so as to become smaller as it approaches the bridge portion 15.

Therefore, as compared with the case where the magnet side portion 15a connected to the magnet mounting hole 11b of the bridge portion 15 extends linearly in the radial direction as shown by the broken line, the portion of the bridge portion 15 connected to the magnet mounting hole 11b The area between the rotor core plate 11 and the peripheral edge thereof can be expanded. Therefore, the proportion of the magnetic flux due to the q-axis current of the coil 51b of the armature 51 is reduced by the hole portion 19, and the decrease in the magnetic flux density of the magnetic flux passing through the salient pole portion 11c can be suppressed. Therefore, the reluctance torque due to the q-axis current of the stator 50 can be further increased, and even if the number of permanent magnets 13 provided on the rotor core plate 11 is reduced, the torque decrease of the motor 1 can be suppressed.

Here, FIG. 7 is a graph showing the relationship between the torque, torque ripple, and terminal voltage of the motor 1 with respect to the width b of the support column portion 17. In this graph, first, the rise angle θ is set to 50 °, and the base 19a of the hole portion 19 is set. Torque and torque ripple characteristics when the width b of the strut portion 17 is changed while the position of is at the same radius position as the bottom of the permanent magnet 13 (hereinafter, referred to as “dh = 0”) (see FIG. 2). Is shown. The permanent magnet 13 had an axial length (rotor core axial length of the permanent magnet 13 / magnet length Lm) of 2.17, a rotation speed of the rotor core 10 of 5400 rpm, and an effective value of the stator current of 78 A. From this graph, it can be seen that when the width b of the strut portion 17 / magnet length is 0.267, the torque is maximum and the torque ripple is minimum, and when the width b of the strut portion 17 is increased, the torque decreases and the torque ripple increases. I understand.

Further, FIG. 8 is a graph showing the relationship between the torque, torque ripple, and terminal voltage of the motor 1 with respect to the rise angle θ of the magnet side portion 15a of the bridge portion 15 forming the hole portion 19 shown in FIG. This graph shows the torque and torque ripple characteristics when the rising angle θ is changed to 40 °, 50 °, 60 °, and 90 °. From this graph, when the rising angle θ is increased to 60 ° and 90 °, the torque is slightly increased, but the torque ripple is also increased. Therefore, in this embodiment, the rising angle θ is set to 50 °.

Further, FIG. 9 is a graph showing the relationship between the torque, torque ripple, and terminal voltage of the motor 1 with respect to the depth dh of the hole 19 shown in FIG. From this graph, it can be seen that the torque and torque ripple hardly change even if the dh is changed.

Next, the relationship between the linear-axis inductance Ld and the horizontal-axis inductance Lq with respect to the phase φ and the amplitude Im of the motor current will be described. FIG. 10 is a graph showing the relationship between the linear-axis inductance Ld, the horizontal-axis inductance Lq, and the salient pole ratio Lq / Ld with respect to the phase φ of the stator current. Further, FIG. 11 is a graph showing the relationship between the linear-axis inductance Ld, the horizontal-axis inductance Lq, and the salient pole ratio Lq / Ld with respect to the amplitude Im of the stator current.

The calculation of the linear-axis inductance Ld and the horizontal-axis inductance Lq with respect to the phase φ and the amplitude Im of the motor current is as follows. ~ 4. Obtain by the procedure of.

1. 1. As current amplitude Im, phase φ,
Apply iu = Im · sin (ωt ＋ φ), iv = Im · sin (ωt ＋ 2π / 3 ＋ φ), iw = Imsin (ωt ＋ 4π / 3 ＋ φ). Here, iu is the current flowing through the U-phase coil, iv is the current flowing through the V-phase coil, and iw is the current flowing through the W-phase coil. The phase φ is the lead phase of the current, and the energization start angle is usually represented by β.

Considering the coordinate axes as the d-axis and the q-axis, the current is defined with the q-axis as 0 °. _{The initial phase θ 0} is included in the equation depending on the positional relationship between the U-phase coil 51b of the armature 51 and the permanent magnet 13 of the rotor core 10.

2. The phase lead angle φ is based on the position where Id = 0 and Iq = √ (3/2) * Im.
_{The initial phase θ 0} is the current phase where the unloaded induced voltage waveform and the current waveform under load exactly overlap, and when adjusting at the rotor initial position, the direction of the magnetic flux created by the U phase is based on the position facing the d-axis. And.

3. 3. The rotor core 10 is rotated by one electric angle cycle while maintaining the current advancing phase φ, and the voltage waveform of each phase is obtained. The voltage value used for the calculation of inductance is obtained by fast Fourier transforming the voltage waveform and extracting the amplitude of the fundamental wave.

4. Inductance is calculated from the voltage equation converted to d-axis and q-axis:
Ld1 = (Vq0-Vq1) / {ω (Id0-Id1)}, Ld2 = (Vq0-Vq2) / {ω (Id0-Id2)} ⇒ Ld = (Ld1 + Ld2 / 2)
Lq = -Vd / {ωIq}]
Outburst ratio: ρ = Lq / Ld
As a general tendency,
・ As φ (β) is advanced, the magnetic saturation of the path of the q-axis magnetic flux decreases, so that Lq increases.
-As for the d-axis, the change in Ld is small because the magnetic resistance of the permanent magnet 13 is originally dominant with respect to the inductance.

As shown in FIGS. 10 and 11, when (width b of strut portion 17 / magnet length) is 0.267, the salient pole has a current amplitude of 110 A and a lead phase of around φ = 20 ° near the rated operating conditions. The ratio ρ = Lq / Lq≈1.58 was obtained. This salient pole ratio ρ ≈ 1.58 is substantially the same as the salient pole ratio ρ ≈ 1.54 when (width b of strut portion 17 / magnet length) is 0.6 (12s8p). When (width b of strut portion 17 / magnet length) is 0.0667, the salient pole ratio ρ ≈ 1.38.

As described above, the shape of the pair of holes 19 formed between the permanent magnets 13 adjacent to each other in the circumferential direction of the rotor core plate 11 is the pair of holes when the central axis of the support column 17 is arranged on the d-axis. 19 is configured to expand outward once (approach the outer circumference of the rotor) and then connect to the magnet inside. By doing so, not only the 12-slot 8-pole type but also the 9-slot 6-pole type can realize the same current, the same magnet, the same torque, and less torque ripple.

1 Motor (Magnet embedded motor)
10 Rotor core 10a Outer peripheral surface 11 Rotor core plate 11a Insertion hole 11b Magnet mounting hole 11c Pole part 12 Rotating shaft 13 Permanent magnet 13a Central axis 15 Bridge part 15a Magnet side part (part)
15b Strut side part (part)
17 Strut 19 Hole 19a Bottom 50 Stator 51 Armature 51a Inner peripheral surface 51b Coil 60 Stator As area g Air gap J Central axis La line Lb Virtual line S Axis center ts Space area φq, φs Magnetic flux

Claims (4)

A rotor structure for a magnet-embedded motor in which a plurality of permanent magnets are embedded in the peripheral edge of a rotor core formed by laminating a large number of rotor core plates in the axial direction, and a stator fixed to face the outer peripheral surface of the magnet-embedded motor rotor. A magnet-embedded motor equipped with
The rotor core plate is
A magnet mounting hole that extends along the circumferential direction and is provided at equal intervals on the outer peripheral portion of the rotor core plate and penetrates in the axial direction of the rotor core plate.
A salient pole portion integrally formed with the rotor core plate on the outer peripheral portion of the rotor core plate on the radial outer side of each of the plurality of magnet mounting holes.
The permanent magnet, which is housed in a state of being fixed to each of the plurality of magnet mounting holes,
A bridge portion formed in a spatial region between the salient poles adjacent to the rotor core plate in the circumferential direction and connecting the radial outer ends of the salient poles adjacent to the circumferential direction, the circumferential direction of the bridge. It is formed on both sides of the support column portion, which extends from the intermediate portion toward the axial center side of the rotor core plate and is surrounded by a support column portion integrally formed with the rotor core plate and end faces of permanent magnets adjacent in the circumferential direction. Formed with a pair of holes,
The portion of the bridge portion forming the hole portion connected to the magnet mounting hole is the central axis (d-axis) of the permanent magnet accommodated in the magnet mounting hole when the rotor core plate is viewed from the axial direction. ) Is an acute angle with respect to the virtual line orthogonal to the radial side of the rotor core plate, and is curved so as to decrease toward the radial side of the rotor core plate.
The strut-side portion of the bridge portion forming the hole portion, which is connected to the strut portion side, is curved toward the permanent magnet side having the end face adjacent to the hole portion as it advances radially outward of the rotor core plate. It is a corner part
The salient pole portion has a radius smaller than the outer diameter of the rotor core plate and is formed in a convex shape .
The air gap is formed so as to be wide on the q-axis electrically orthogonal to the d-axis passing through the center of the permanent magnet along the radial direction of the rotor core plate and narrow on the d-axis. magnet embedded motor, characterized. The strut is magnet embedded motor according to claim 1, characterized in that extends towards the axial direction of the rotor core plate. The pair of holes, the magnet embedded motor according to claim 1 or 2, characterized in that it is formed symmetrically in the circumferential direction of the rotor core plate the strut as the center. A motor casing for rotatably supporting the magnet embedded motor rotor,
The stator, Ru is fixed to the inner surface of the motor case
The magnet-embedded motor according to any one of claims 1 to 3.

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