JP5609016B2 - Permanent magnet type rotating machine - Google Patents

Description

  The present invention relates to a permanent magnet type rotating machine that includes a stator and a rotor that rotates oppositely with a predetermined gap.

It is well known that this kind of permanent magnet type rotating machine generates a kind of torque pulsation called cogging torque. When the cogging torque is large in the permanent magnet type rotating machine, problems such as deterioration in control performance of the rotating machine and generation of noise occur.
The stator of the permanent magnet type rotating machine includes a closed slot type in which a slot around which an exciting coil is wound is closed (for example, see Patent Document 1) and an open slot type in which the rotor side of the slot is open (for example, Patent Document 2). And Patent Document 3).

Cogging torque is generated because the magnetic energy changes as the rotor rotates. That is, the magnetoresistance changes depending on the rotor. That is, the cogging torque can be reduced if the change in the magnetic resistance is reduced by the rotation of the rotor.
Comparing the closed slot type and the open slot type, the closed slot type can suppress the change of the magnetic resistance, so that the cogging torque can be reduced.

By the way, the torque T of the permanent magnet type rotating machine is represented by the following equation when the number of pole pairs is Pn, the interlinkage magnetic flux Ψa formed by the permanent magnet, the d-axis inductance Ld, the q-axis inductance Lq, the d-axis current id, and the q-axis current iq. Is done.
T = Pn · Ψa · iq + Pn (Ld−Lq) id · iq (1)
The first term on the right side of equation (1) represents the torque generated by the interaction between the magnetic flux produced by the permanent magnet and the current, and the second term represents the reluctance torque.

  In the case of the closed slot type as in Patent Document 1 described above, as shown in FIG. 8, adjacent magnetic poles so as to close the slot 103 around which the exciting coil 102 is wound on the inner diameter side facing the rotor of the stator 101. A bridge 105 that connects the inner diameter side between the teeth 104 is formed. In this closed slot type, since the slot 103 is closed, there is little change in the magnetic energy of the air in the circumferential direction of the stator inner diameter, and the cogging torque is reduced. However, since the magnetic resistance of the bridge 105 is very small compared to air, most of the magnetic flux created by the permanent magnet disposed in the rotor passes through the magnetic path ML1 formed by the magnetic pole teeth 104 and the yoke 106. A part of the magnetic path ML2 flows through the bridge 105. The magnetic flux passing through the magnetic path ML2 does not contribute to the torque generation of the rotating machine. That is, the leakage magnetic flux cannot effectively generate torque, and Ψa of the first term on the right side in the above-described equation (1) becomes small, so that torque may not be generated effectively.

Further, as described in Patent Document 2, in the open slot type permanent magnet type motor for the purpose of improving the demagnetization resistance, the width of the opening between the adjacent teeth (tooth opening width La) The relationship between the air gap Lg between the stator and the rotor is set to 0.31Lg <La ≦ 2.01Lg so that the demagnetizing magnetic flux does not flow to the stator, thereby improving the demagnetization resistance.
With the recent increase in the density of permanent magnet type rotating machines, the air gap between the stator and the rotor has become very narrow. This also shows that the slot opening width of the conventional example described in Patent Document 2 is very small.

From the viewpoint of cogging torque, if the slot opening width is narrow, the cogging torque is small, although it does not reach the closed slot type.
As for demagnetization, when concentrated winding is employed, and in particular 120 ° conduction, as shown in FIG. 9 (a), there are portions where stator teeth adjacent to each other form different poles. In this case, a magnetic circuit having a high magnetic flux density is formed, and local demagnetization tends to occur. In order to make it difficult for the demagnetizing field to be applied to the permanent magnet, as shown in FIG. 9B, it is necessary to move the permanent magnet away from the portion where the magnetic circuit of high magnetic flux density is formed at the stator tooth tip. (See, for example, Non-Patent Document 1).

Japanese Patent No. 3107177 Japanese Patent No. 3076006 JP 2004-96803 A

"Design and control of embedded magnet synchronous motor" October 25, 2001, published by Ohm Co., Ltd.

However, the conventional example described in Non-Patent Document 1 discloses that leakage magnetic flux is reduced and the demagnetization resistance is improved. However, the slot opening width is smaller than that of the conventional example described in Patent Document 2. Therefore, it can be predicted that the cogging torque becomes very large.
Accordingly, the present invention has been made paying attention to the unsolved problems of the above-described conventional example, and an object thereof is to provide a permanent magnet type rotating machine capable of keeping cogging torque low while reducing leakage magnetic flux. It is said.

To achieve the above object, a permanent magnet type rotating machine according to an embodiment of the present invention includes a stator around which an exciting coil is wound, and a permanent magnet that rotates opposite to the stator with a predetermined gap therebetween. A stator having a plurality of magnetic pole teeth projecting radially inward at equal intervals in the circumferential direction of a cylindrical yoke. The magnetic pole teeth have a magnetic leg portion connected to the yoke, and a tapered wedge-like protrusion portion protruding in the circumferential direction at the tip of the magnetic leg portion. And an inclined inner surface portion extending obliquely from the base portion of the magnetic leg portion toward the circumferential surface side, and an inclined inner surface portion extending from the circumferential surface of the tip toward the inclined inner surface portion side. A slanted outer surface part, and an acute tip at the intersection of the slanted inner surface part and the slanted outer surface part. Form, contacting line a sharp tip comrades of the wedge protrusion in the axial directions of adjacent magnetic teeth, between the intersections of said inclined outer surface portion of the wedge-shaped projecting portion in the magnetic pole teeth adjacent the circumferential surface The gap length, which is the length on the circumferential surface of the stator, is set to 0.018 times or more and 0.053 times or less of one slot pitch .

In the permanent magnet type rotating machine according to another aspect of the present invention, when the number of magnetic poles of the permanent magnet of the rotor is 2n (n is a positive integer), the number of slots of the stator is 3n, and the excitation is performed. The coil is characterized by being concentrated winding in which one coil is wound around the magnetic pole teeth.
Furthermore, in the permanent magnet type rotating machine according to another aspect of the present invention, the wedge-shaped projecting portion has a distance from an inner circumference of the stator to a connection point of the wedge-shaped projecting portion, which is 0.018 of 1 slot pitch. It is characterized by having doubled .

Furthermore, the permanent magnet type rotating machine according to another embodiment of the present invention, before Symbol permanent magnets has a trapezoidal magnetization region where the magnetic flux density distribution is magnetized in a trapezoidal shape, trapezoid wave magnetization region The upper base portion angle is set to an electrical angle of 114 degrees or more and 135 degrees or less.

Further, in the permanent magnet type rotating machine according to another aspect of the present invention, the wedge-shaped projecting portion has a distance from an inner circumference of the stator to a connection point of the wedge-shaped projecting portion of 0 . 04 4 times or more and 0.062 times or less, and the length on the circumferential surface of the stator between the intersections of the inclined outer surface portion and the circumferential surface of the wedge-shaped protrusions in the adjacent magnetic teeth it is characterized in that the gap length is set to less than 0.0 53 times more than 0.018 times the pitch of one slot is.
Furthermore, in the permanent magnet type rotating machine according to another aspect of the present invention, the permanent magnet has a trapezoidal wave-shaped magnetization region in which the magnetic flux density distribution is magnetized in a trapezoidal wave shape, and the upper side of the trapezoidal wave-shaped magnetization region is The bottom angle is characterized in that the electrical angle is set to 119 degrees or more and 143 degrees or less.

  Furthermore, a permanent magnet type rotating machine according to another embodiment of the present invention is characterized in that the permanent magnet is skewed.

  According to the present invention, there is a tapered wedge-shaped protruding portion protruding in the circumferential direction at the tip of the magnetic pole teeth of the stator, and the wedge-shaped protruding portions of adjacent magnetic pole teeth are brought into contact with each other. As a result, the leakage flux can be reduced and the cogging torque can be reduced.

It is an axial end view showing a permanent magnet type synchronous rotating machine showing an embodiment of the present invention. It is an expansion perspective view of the state which expanded the stator core of FIG. It is an enlarged view which shows the rotor of FIG. It is a characteristic diagram which shows the relationship between the upper bottom part angle of a permanent magnet, and cogging torque at the time of multiplying the height from a stator inner periphery circle | round | yen to the connection point of a wedge-shaped protrusion part 0.018 with respect to 1 slot pitch. It is a characteristic diagram showing the relationship between the angle of the upper base of the permanent magnet and the cogging torque when the height from the inner circumference of the stator to the connection point of the wedge-shaped protrusion is 0.044 times with respect to one slot pitch. . It is a characteristic diagram which shows the relationship between the upper base part angle of a permanent magnet, and cogging torque when the height from a stator inner periphery circle | round | yen to the connection point of a wedge-shaped protrusion part is 0.0162 time with respect to 1 slot pitch. It is an expansion perspective view of the state where the stator core which shows other embodiments of the present invention was developed. It is an expanded view which shows the conventional closed slot type stator. It is an expanded view which shows the conventional open slot type stator, (a) shows the shape before a demagnetization countermeasure, (b) shows the shape after a demagnetization countermeasure.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a sectional view showing a first embodiment when the present invention is applied to a permanent magnet type synchronous rotating machine. In FIG. 1, a permanent magnet type synchronous rotating machine 1 is a surface magnet type synchronous rotating machine. This permanent magnet type synchronous rotating machine 1 has a cylindrical frame 2. A stator 3 formed of a cylindrical laminated steel plate is fixed on the inner peripheral side of the cylindrical frame 2, and formed on the inner peripheral side of the stator 3 by a laminated steel plate facing each other with a predetermined gap. A rotor 4 is arranged. The rotor 4 is supported by a rotating shaft 5 and is rotatably arranged.

  The stator 3 has a configuration in which a stator core 11 that is divided into nine in the circumferential direction is connected to the inner circumferential side of the cylindrical frame 2 in a circumferential direction. As shown in FIG. 2, each stator core 11 includes a yoke 12 having an outer peripheral surface formed in a cylindrical surface and an inner peripheral surface formed as a nine-sided cylinder inner surface, and a circumferential direction of the inner peripheral surface of the yoke 12. The magnetic pole teeth 13 are formed to protrude in the radial direction from the central portion.

  The magnetic teeth 13 include a magnetic leg portion 13a connected to the yoke 12, and a tapered wedge-shaped protrusion portion 13b protruding in the circumferential direction at the tip of the magnetic leg portion 13a. As shown in an enlarged view in FIG. 2, the wedge-shaped protruding portion 13b includes a circumferential surface 13c at the tip, an inclined inner surface portion 13e extending from the base portion 13d of the magnetic leg portion 13a, and a circumferential surface 13c at the tip. It is composed of an inclined outer surface portion 13f that extends by inclining and contacts the inclined inner surface portion 13e.

A slot 14 is formed by the yoke 12 and the magnetic teeth 13 of the adjacent stator core 11, and the tips of the wedge-shaped protrusions 13b of the adjacent magnetic teeth 13 are in contact with each other. A gap portion 13g is formed on the outer peripheral side of the circumferential surface 13c by the inclined outer surface portion 13f of the wedge-shaped protrusions 13b that are in contact with each other.
Each magnetic pole tooth 13 has a concentrated winding structure in which one exciting coil 16 is wound around the magnetic leg portion 13a.

On the other hand, the rotor 4 has a configuration in which, for example, a permanent magnet 22 having a 6-pole configuration is disposed on a surface that is an outer peripheral surface of the cylindrical rotor core 21 so that magnetic poles adjacent in the circumferential direction have different polarities. Have. Here, the permanent magnet 22 is composed of a rare earth magnet.
Further, as shown in FIG. 3, the permanent magnet 22 has a trapezoidal wave-like magnetized region 23 magnetized in a trapezoidal wave shape shown in hatching, and the trapezoidal wave-like magnetized region 23 from the center of the rotor core 21. The angle between the lines passing through the circumferential end of the upper bottom portion 23a is set as the upper bottom portion angle θm, and the angles of the magnetized inclined portions on both sides of the upper bottom portion angle θm are set as θa.

Then, the height of the wedge-shaped projecting portion tip, that is, the height of the gap portion 13g, which is the height from the extension line of the circumferential surface 13c of the wedge-shaped projecting portion 13b of the magnetic tooth 13 to the connecting point 13h of the wedge-shaped projecting portion 13b that contacts each other h, S is the gap length between the intersections of the inclined outer surface portion 13f of the adjacent magnetic teeth 13 and the circumferential surface 13c on the extension line of the circumferential surface 13c, and P is the slot pitch between the adjacent slots 14. .

  The present inventors changed the value h / P obtained by dividing the height h of the wedge-shaped protruding portion by 1 slot pitch P and the value S / P obtained by dividing the gap length S by 1 slot pitch P to make permanent changes. As a result of variously changing the upper base angle θm of the upper base portion 23a of the trapezoidal wave-like magnetized region 23 of the magnet 22 and performing magnetic field analysis simulation, by setting h / P and S / P within a predetermined range, adjacent wedge shapes It was found that the demagnetization resistance can be improved and the cogging torque can be kept low while reducing the leakage magnetic flux flowing through the protrusion.

  That is, for example, when the S / P is set to 0.018, 0.035, 0.053, and 0.088 in a state where the h / P is set to 0.018, the results of the magnetic field analysis simulation are shown in FIG. 3 shows. In FIG. 3, when S / P = 0.088, as shown by the one-dot chain line, the upper base angle θm of the permanent magnet 22 is an electrical angle of 105 degrees and a relatively large cogging torque is obtained. As the upper base angle θm increases, the cogging torque rapidly increases up to approximately an electrical angle of 117 degrees, and then the cogging torque becomes constant until the upper base angle θm reaches an electrical angle of about 128 degrees, and then the upper base angle θm increases. The cogging torque increases rapidly in response to.

  Further, when S / P = 0.053 is set, as shown by the dotted line, the upper base portion angle θm of the permanent magnet 22 is lower than when S / P = 0.088 at an electrical angle of 105 degrees, After that, the cogging torque gradually increases as the upper bottom angle θm increases, and after the cogging torque reaches a peak value near the electrical angle of 114 degrees, the cogging torque gradually decreases as the upper bottom angle θm increases. The cogging torque takes a minimum value near an electrical angle of 126 degrees, and then the cogging torque increases relatively slowly as the upper bottom angle θm increases.

  Further, when S / P = 0.035 is set, as shown in the two-dot chain line, the upper base angle θm of the permanent magnet 22 is 105 degrees in electrical angle and S / P = 0.053. Low, the cogging torque increases very slowly as the upper bottom angle θm increases, and after the cogging torque takes a peak value near the electrical angle of 112 degrees, the cogging torque becomes relatively gentle as the upper bottom angle θm increases. Decreases, the cogging torque takes a minimum value near the electrical angle of 124 degrees, and then the cogging torque gradually increases as the upper bottom angle θm increases.

  Furthermore, when S / P = 0.018 is set, as shown by the solid line, the upper base angle θm of the permanent magnet 22 is 105 degrees in electrical angle and becomes a cogging torque smaller than S / P = 0.088, and thereafter As the upper bottom angle θm increases, the cogging torque increases gently, takes a minimum value near the electrical angle of 120 degrees, and then increases relatively slowly as the upper bottom angle θm increases, The cogging torque gradually increases from around the electrical angle 135.

  As apparent from the magnetic field analysis simulation result of FIG. 3, when h / P = 0.018, when S / P = 0.088, the cogging torque due to the increase in the upper bottom angle θm of the permanent magnet 22 is obtained. The amount of fluctuation is large. However, when the S / P is set in the range of 0.053 or less and 0.018 or more, the cogging torque value can be suppressed to a small value. Moreover, when the upper base angle θm is set to an electrical angle of 114 degrees or more and an electrical angle of 135 degrees or less, it becomes possible to select the minimum point of the cogging torque by reducing the fluctuation range of the cogging torque, and the cogging torque. Can be reduced.

  When h / P = 0.044 and h / P = 0.062 are set, as shown in FIGS. 5 and 6, respectively, S / P is set to h / P = 0 described above. Similarly to the case of setting to .018, when 0.088, 0.053, 0.035 and 0.018 are set, the cogging torque change with respect to the upper base angle θm of the permanent magnet 22 is S / P = 0. When set to .088, the cogging torque is high as a whole, and the cogging torque increases as the upper bottom angle θm increases. On the other hand, when the S / P is set to 0.053, 0.035, and 0.018, the cogging torque can be suppressed low, and the fluctuation range of the cogging torque can be suppressed. In addition, by setting the upper base angle θm of the permanent magnet 22 in the range of electrical angle 119 degrees or more and electrical angle 143 degrees or less, it becomes possible to select the minimum point of the cogging torque, and to further reduce the cogging torque. Can do.

  Thus, in the present invention, the tapered wedge-shaped protruding portion 13b protruding in the circumferential direction is disposed at the tip of the magnetic teeth 13 of the stator 3, and the tips of the wedge-shaped protruding portions 13b of the adjacent magnetic teeth 13 are brought into contact with each other. Thus, the cogging torque can be reduced while suppressing the leakage magnetic flux. In addition, since the inclined outer surface portion 13f is formed on the wedge-shaped protrusion 13b so as to be away from the permanent magnet 22 of the rotor 4, the demagnetization resistance can be increased.

Here, by setting S / P to a range of 0.018 or more and 0.053 or less, the cogging torque can be reduced regardless of the value of h / P.
Further, by setting h / P to 0.018 and setting S / P to a range of 0.018 or more and 0.053 or less, the cogging torque can be reduced, and the rotor 4 becomes permanent. By forming a trapezoidal wave-like magnetized region 23 in the magnet 22 and setting the upper base angle θm of the trapezoidal wave-like magnetized region 23 to an electric angle of 114 degrees or more and an electric angle of 135 degrees or less, the cogging torque is minimized. Can be set near.

  Similarly, when h / P is set to 0.044 and 0.062, the cogging torque can be reduced by setting S / P to a range of 0.018 or more and 0.053 or less, Furthermore, by forming a trapezoidal wave-like magnetized region 23 in the permanent magnet 22 of the rotor 4 and setting the upper base angle θm of the trapezoidal wave-like magnetized region 23 to a range of an electrical angle of 119 degrees or more and an electrical angle of 143 degrees or less. The cogging torque can be set near the minimum point.

In the above embodiment, the case where the magnetic pole teeth 13 of the stator 3 and the permanent magnet 22 of the rotor 4 are not skewed has been described. However, the present invention is not limited to this, and the magnetic pole teeth 13 of the stator 3 are not limited thereto. In addition, the cogging torque can be further reduced by applying a skew to any of the permanent magnets 22 of the rotor 4.
Moreover, in the said embodiment, although the case where it was set as the line contact state which made the acute-angle front-end | tips of the wedge-shaped protrusion part 13b of the adjacent magnetic pole teeth 13 contact, it is not limited to this, FIG. As shown, the wedge-shaped protrusions 13b may be brought into surface contact with each other as a shape in which the tip of the wedge-shaped protrusion 13b is cut off. In this case, since the leakage magnetic flux increases as the contact area increases, the cogging torque can be suppressed by reducing the contact area as much as possible.

Furthermore, in the above embodiment, the case where the divided stator core 11 is applied has been described. However, the present invention is not limited to this, and the magnetic pole teeth 13 are formed at equal intervals in the circumferential direction on the cylindrical yoke 12. You may make it do.
Furthermore, in the above embodiment, the case where the rotor 4 is constituted by a surface magnet type rotor has been described. However, the present invention is not limited to this, and a permanent magnet is embedded in the surface of the rotor core 21 to make it permanent. It can also be comprised with the embedded magnet type | mold rotor which exposed the front of the magnet.

  Furthermore, in the above embodiment, in the above embodiment, the present invention is a rotating machine in which the magnetic pole teeth 13 and the slots 14 of the stator 3 are nine, and the number of poles of the permanent magnet 22 of the rotor 4 is six. Although the case where the present invention is applied has been described, the present invention is not limited to this, and the present invention is applied to a rotating machine having 3n slots when the number of poles of the permanent magnet 22 is 2n (n is a positive integer). can do.

  DESCRIPTION OF SYMBOLS 1 ... Permanent magnet type synchronous rotating machine, 3 ... Stator, 4 ... Rotor, 5 ... Rotating shaft, 11 ... Stator core, 12 ... Yoke, 13 ... Magnetic pole teeth, 13a ... Magnetic leg part, 13b ... Wedge-like protrusion part , 13c: circumferential surface, 13d: root portion, 13e: inclined inner surface portion, 13f: inclined outer surface portion, 13g ... gap portion, 13h ... coupling point, 14 ... slot, 16 ... exciting coil, 21 ... rotor core, 22 ... Permanent magnet, 23 ... Trapezoidal wave-shaped magnetized region, 23a ... Upper bottom

Claims (7)

A permanent magnet type rotating machine comprising a stator around which an exciting coil is wound, and a rotor having a permanent magnet that rotates in opposition to the stator across a predetermined gap,
The stator has a stator core formed with a plurality of magnetic pole teeth projecting radially inward at regular intervals in the circumferential direction of a cylindrical yoke, and the magnetic pole teeth are magnets connected to the yoke. A leg portion and a tapered wedge-shaped projecting portion projecting in a circumferential direction at a tip of the magnetic leg portion, and the wedge-shaped projecting portion is formed from the circumferential surface of the tip and a base portion of the magnetic leg portion to the circle. An inclined inner surface portion extending obliquely toward the peripheral surface side, and an inclined outer surface portion extending inclinedly from the circumferential surface of the tip toward the inclined inner surface portion side and in contact with the inclined inner surface portion, the inclined inner surface portion and the inclined outer surface Forming an acute tip at the intersection with the part, and making the sharp tip of the wedge-shaped protrusions of adjacent magnetic teeth teeth line contact with each other in the axial direction ,
The gap length, which is the length on the circumferential surface of the stator, between the intersections of the inclined outer surface portion of the wedge-shaped projecting portion and the circumferential surface of the adjacent magnetic teeth is 0.018 times the pitch of one slot. A permanent magnet type rotating machine characterized by being set to 0.053 times or less .   When the number of magnetic poles of the permanent magnet of the rotor is 2n (n is a positive integer), the number of slots of the stator is 3n, and the exciting coil is a concentrated winding in which one coil is wound around the magnetic teeth. The permanent magnet type rotating machine according to claim 1, wherein the permanent magnet type rotating machine is provided. 3. The permanent wedge according to claim 1 , wherein the wedge-shaped projecting portion has a distance from an inner circumference of the stator to a connection point of the wedge-shaped projecting portion being 0.018 times a slot pitch. Magnet type rotating machine. The permanent magnet has a trapezoidal wave-like magnetized region in which the magnetic flux density distribution is magnetized in a trapezoidal wave shape, and the upper base angle of the trapezoidal wave-like magnetized region is set to an electrical angle of 114 degrees or more and 135 degrees or less. The permanent magnet type rotating machine according to any one of claims 1 to 3, wherein The wedge-shaped protrusion is characterized in that a distance from an inner circumferential circle of the stator to a connection point of the wedge-shaped protrusion is set to be 0.044 times or more and 0.062 times or less of one slot pitch. Item 3. The permanent magnet type rotating machine according to Item 1 or 2 . The permanent magnet has a trapezoidal wave-shaped magnetized region in which the magnetic flux density distribution is magnetized in a trapezoidal wave shape, and the upper base angle of the trapezoidal wave-shaped magnetized region is set to an electrical angle of 119 degrees or more and 143 degrees or less. The permanent magnet type rotating machine according to claim 5 , characterized in that: The permanent magnet type rotating machine according to any one of claims 1 to 6, wherein the permanent magnet is skewed .

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