JP5671860B2 - Rotating electric machine - Google Patents

Description

  The present invention relates to a rotating electrical machine.

  Patent Document 1 discloses a rotating electric machine that combines a low coercivity permanent magnet and a high coercivity permanent magnet to change the magnetization state of the low coercivity permanent magnet according to operation.

JP 2006-280195 A

  However, in the conventional rotating electrical machine described above, when a large current is passed to obtain a high torque, the demagnetizing field causes the low coercivity permanent magnet to be demagnetized. When a + d-axis current is applied to avoid demagnetization, a reverse torque is generated, and there is a problem that the torque further decreases.

  The present invention has been made paying attention to such a conventional problem, and an object of the present invention is to provide a rotating electrical machine capable of preventing demagnetization of a permanent magnet during high torque operation.

  The present invention solves the above problems by the following means.

The present invention relates to a rotary electric machine including a rotor over the insertion of the permanent magnets to the rotor core. The rotor core includes a low magnetic permeability layer having a lower magnetic permeability than the rotor core for each fixed mechanical angle, and the permanent magnet is provided between the low magnetic permeability layers provided for each fixed mechanical angle. A plurality of permanent magnets form one magnetic pole, and at least one of the plurality of permanent magnets forming the one magnetic pole has a different coercive force from other permanent magnets. The low-permeability layer is arranged on the q-axis that is electrically and magnetically orthogonal to the d-axis, which is the direction of the magnetic flux by the magnetic poles formed by a plurality of permanent magnets, and has a plurality of convexities toward the rotation center of the rotor Consists of a substantially arc shape. Moreover, it further includes a permanent magnet disposed between a plurality of substantially arcs constituting the low permeability layer.

  According to the present invention, during high-speed rotation operation, the permanent magnet having a low coercive force reverses the magnetic pole due to the demagnetizing field and the voltage induced in the stator is suppressed, so that the increase in the rotational speed of the rotor can be suppressed. During high torque operation, the magnetic pole on the rotor side is attracted to the magnetic pole on the stator side, and the magnetic flux does not become a demagnetizing field, so that demagnetization of the permanent magnet can be prevented.

It is sectional drawing which shows 1st Embodiment of the rotor of the rotary electric machine by this invention, and shows 1/2 (mechanical angle 180 degrees) of a perimeter. It is a figure which shows a mode when performing a maximum torque driving | operation. It is a figure which shows a mode when performing high-speed rotation driving | operation. It is sectional drawing which shows 2nd Embodiment of the rotor of the rotary electric machine by this invention, and shows 1/2 (mechanical angle 180 degrees) of a perimeter. It is sectional drawing which shows 3rd Embodiment of the rotor of the rotary electric machine by this invention, and shows 1/2 (mechanical angle 180 degrees) of a perimeter. It is a figure which shows 4th Embodiment of the rotor of the rotary electric machine by this invention. It is a figure which shows 5th Embodiment of the rotor of the rotary electric machine by this invention. It is a figure which shows 6th Embodiment of the rotor of the rotary electric machine by this invention.

Hereinafter, embodiments for carrying out the present invention will be described in more detail with reference to the drawings.
(First embodiment)
FIG. 1 is a cross-sectional view showing a first embodiment of a rotor of a rotating electrical machine according to the present invention, and shows a half of the entire circumference (mechanical angle 180 °).

  A rotor 1 of a rotating electrical machine includes a rotor shaft 10, a rotor core 20, and permanent magnets 31 and 32.

  The rotor shaft 10 is a rotating shaft of the rotor 1.

  The rotor core 20 is provided around the rotor shaft 10. The rotor core 20 is formed by laminating a number of electromagnetic steel plates in the rotor shaft direction. The rotor core 20 includes low magnetic permeability layers 211 to 214. The low magnetic permeability layers 211 to 214 are flux barriers having a low magnetic permeability compared to the electromagnetic steel plate portion of the rotor core 20 and difficult to pass magnetic flux (flux). The low magnetic permeability layers 211 to 214 may be voids (air layers) formed in the rotor core 20 or the voids may be filled with a low magnetic permeability material. The low magnetic permeability layers 211 to 214 are formed for every fixed mechanical angle. In this embodiment, it is formed every mechanical angle 180 °. That is, in this embodiment, the low magnetic permeability layers 211 to 214 are formed at six places on the entire circumference. The low magnetic permeability layers 211 to 214 are arranged on the q axis. The q axis will be described later. The low magnetic permeability layers 211 to 213 have a plurality of substantially arc shapes that protrude toward the rotor shaft 10. The low magnetic permeability layer 214 has a shape in which one edge is along the low magnetic permeability layer 213 and the other edge is along the outer periphery of the rotor shaft 10.

  The permanent magnets 31 and 32 are disposed between the low magnetic permeability layers 211 to 214 formed at fixed mechanical angles. In this embodiment, it is formed every mechanical angle 180 °. That is, in this embodiment, it arrange | positions at six places in a perimeter. There are two permanent magnets 32 forming one magnetic pole. That is, one magnetic pole is formed by the three permanent magnets of the two permanent magnets 32 and 31. The adjacent magnetic poles are alternately different. That is, in the upper right permanent magnets 31 and 32, the rotor outer peripheral side is the N pole, and the rotor shaft side is the S pole. In the upper left permanent magnets 31 and 32, the rotor outer peripheral side is the S pole, and the rotor shaft side is the N pole. The direction of the magnetic flux produced by the three permanent magnets forming one magnetic pole is the d-axis. The permanent magnet 31 is disposed on the d axis. The two permanent magnets 32 are located on both sides of the permanent magnet 31. The direction perpendicular to the d-axis electrically and magnetically is the q-axis. And the three permanent magnets of the permanent magnet 31 and the two permanent magnets 32 are arrange | positioned in the range within 180 degrees of electrical angles. That is, the three permanent magnets of the permanent magnet 31 and the two permanent magnets 32 are arranged in a range sandwiched between two q axes. The permanent magnet 31 and the permanent magnet 32 have different coercive forces. The permanent magnet 31 has a higher coercive force than the permanent magnet 32. In other words, the permanent magnet 32 has a lower coercive force than the permanent magnet 31. The permanent magnet 31 is thinner than the permanent magnet 32. In other words, the permanent magnet 32 is thicker than the permanent magnet 31.

  Next, the function and effect of the first embodiment will be described.

  FIG. 2 is a diagram illustrating a state when the maximum torque operation is performed.

  FIG. 2A shows a state in which the maximum torque operation is performed by utilizing the magnet torque to the maximum extent.

In the case of operating the maximum torque counterclockwise in FIG. 2A using the rotor 1 of the present embodiment, in order to make maximum use of the magnet torque, a stator magnetic field as shown in FIG. To do. That is, an S pole is formed on the stator 2 on the q axis (directly above FIG. 2A). Then, an N pole is formed on the q-axis located on the upper right side.
In this way, the magnetic pole (N pole) formed by the permanent magnets 31 and 32 repels the N pole of the stator 2 and is attracted to the S pole, so that the magnet torque can be utilized to the maximum.

  FIG. 2B shows a state in which the maximum torque operation is performed by utilizing the reluctance torque to the maximum.

  Similarly, in the case where the maximum torque is operated counterclockwise in FIG. 2B using the rotor 1 of the present embodiment, in order to make maximum use of the reluctance torque, a stator as shown in FIG. Use a magnetic field. That is, the S pole is formed on the stator 2 slightly advanced from the d axis. Then, the N pole is formed in the stator 2 which is electrically delayed by 180 ° from the S pole. If it does in this way, the magnetic flux between the north pole-south pole of a stator will pass through the electromagnetic steel plate part between the low magnetic permeability layers 211-214. The rotor rotates counterclockwise so that this magnetic flux path is the shortest. Therefore, the reluctance torque can be utilized to the maximum by using such a stator magnetic field.

  FIG. 2C shows a state in which the maximum torque operation is performed by using the combined torque of the magnet torque and the reluctance torque to the maximum extent.

  As described above, the stator magnetic field when the magnet torque is used to the maximum is different from the stator magnetic field when the reluctance torque is used to the maximum. Therefore, in order to make maximum use of the combined torque of both torques, as shown in FIG. 2 (C), the stator magnetic field between FIG. 2 (A) and FIG. 2 (B) is used. When this is done, the magnetic pole (N pole) formed by the permanent magnets 31 and 32 is attracted to the S pole of the stator 2. That is, since the rotor-side magnetic pole is attracted to the stator-side magnetic pole, the magnetic flux becomes as indicated by an arrow in FIG. 2C and does not become a demagnetizing field, so the permanent magnet does not demagnetize.

  FIG. 3 is a diagram illustrating a state when the high-speed rotation operation is performed.

  As the rotation of the rotor increases, the voltage induced on the stator side by the permanent magnet embedded in the rotor increases. This makes it difficult for current to flow through the stator, making it difficult to increase the rotational speed.

  However, if the rotor of this embodiment is used to form an N pole in the d-axis stator 2 as shown in FIG. 3 (this may be an extremely short time in a pulse manner), the permanent magnet has a low coercive force due to the demagnetizing field. The magnetic pole of the magnet 32 is reversed. That is, in the permanent magnet 32, the rotor outer peripheral side becomes the S pole, and the rotor shaft side becomes the N pole. Then, as shown in FIG. 3, since a part of magnetic flux passes from the permanent magnet 31 to the permanent magnet 32, the voltage induced in the stator 2 is suppressed. And since the rotor 1 rotates at high speed by forming the magnetic field which rotates at high speed in the stator 2, the restriction | limiting increase in the rotational speed of the rotor 1 can be suppressed.

  Further, according to the present embodiment, the high coercivity permanent magnet 31 is disposed on the d-axis, the low coercivity permanent magnets 32 are disposed on both sides thereof, and one magnetic pole is composed of three permanent magnets. According to such a configuration, even if magnetization / demagnetization occurs, the magnetomotive force distribution is symmetric about the d axis. Further, as the number of magnets increases, the leakage magnetic flux at the end of the magnet increases, and the magnetic flux that can be effectively utilized decreases. However, with the configuration as in this embodiment, one magnetic pole with the minimum number of magnets is necessary. Will be constructed. Therefore, leakage at the end of the magnet can be minimized and the torque per magnet amount can be increased.

  Further, the magnets constituting one magnetic pole are disposed within an electrical angle of 180 degrees, and as a result, no magnet is disposed between the poles.

  Further, the low coercivity permanent magnet 32 is thicker than the high coercivity permanent magnet 31.

  The low coercivity permanent magnet 32 is completely magnetized by the field from the stator so that the residual magnetic flux density is increased when a large torque is generated. The maximum thickness of the magnet is determined from the magnetic field strength that can be generated by the stator. On the other hand, when the motor rotates, a demagnetizing field acts on the permanent magnet. The minimum thickness must be determined so that demagnetization does not occur due to this demagnetizing field. Therefore, the low coercivity permanent magnet 32 is thicker than the high coercivity permanent magnet 31.

  In this way, by making the low coercivity permanent magnet 32 thicker than the high coercivity permanent magnet 31, magnetization demagnetization without affecting the magnetization state of the low coercivity magnet 32 in normal operation. You will be able to control.

  Furthermore, the magnetic steel sheet portion sandwiched between the low permeability layers 211 to 214 by the low permeability layers 211 to 214 has a substantially arc shape. Therefore, the shape of the electromagnetic steel sheet portion and the d-axis path are almost the same shape, and do not hinder the flow of magnetic flux.

(Second Embodiment)
FIG. 4 is a cross-sectional view showing a second embodiment of the rotor of the rotating electrical machine according to the present invention, and shows a half of the entire circumference (mechanical angle 180 °).

  In the following description, parts having the same functions as those described above are denoted by the same reference numerals, and redundant description is omitted as appropriate.

  In the present embodiment, the rotor of the rotating electrical machine has a magnetic pole formed by three permanent magnets (one high coercivity permanent magnet 31 and two low coercivity permanent magnets 32), and the permanent magnet 31 is magnetized. The angle θ [deg] formed by the direction vector and the magnetization direction vector of the permanent magnet 32 is set to satisfy the following equation (1).

In FIG. 4, since there are 6 poles, θ = 30 deg.
With this configuration, the magnetization direction of each permanent magnet coincides with the d-axis magnetic path direction, so that magnetization / demagnetization is correctly performed. That is, since the orientation direction of the low coercive force magnet matches the direction in which the d-axis magnetic flux flows, magnetization / demagnetization is correctly performed.

  Although the effect decreases with deviation from the above equation (1), the effect is not lost at all. Therefore, θ not only strictly satisfies the above equation (1), but may have a certain amount of deviation.

(Third embodiment)
FIG. 5 is a cross-sectional view showing a third embodiment of the rotor of the rotating electrical machine according to the present invention, and shows a half of the entire circumference (mechanical angle 180 °).

  In the present embodiment, in the rotor of the rotating electrical machine, in particular, the low magnetic permeability layers 211 to 214 are arranged on the q axis and are disposed within an electric angle range of 30 to 50 degrees with the q axis as the center. That is, in FIG. 5, φ = 30 to 50 deg.

  The magnetic steel sheet portion sandwiched between the low magnetic permeability layers 211 to 214 by the low magnetic permeability layers 211 to 214 has a substantially arc shape. Therefore, the shape of the electromagnetic steel sheet portion and the d-axis path are almost the same shape, and do not hinder the flow of magnetic flux.

  Further, the low magnetic permeability layers 211 to 214 are arranged on the q axis and are disposed within an electric angle range of 30 to 50 degrees with the q axis as the center. By arranging in this way, 130 to 150 degrees out of one magnetic pole 180 degrees becomes an angle at which magnetic flux is generated, and distortion included in the gap magnetic flux density distribution is suppressed to a small level (generally, electric angle around 140 degrees). To reduce distortion).

  By setting the occupation width of the q-axis in terms of the electrical angle as described above, the distortion rate of the gap magnetic flux density distribution can be suppressed to a low level. That is, the fundamental wave ratio per the same magnet amount can be increased and the iron loss can be reduced.

(Fourth embodiment)
FIG. 6 is a view showing a fourth embodiment of the rotor of the rotating electrical machine according to the present invention.

  As shown in FIG. 6A, the d-axis magnetic path is a magnetic path that is orthogonal to the q-axis and coincides with the d-axis.

  As shown in FIG. 6B, the q-axis magnetic path is a magnetic path that is orthogonal to the d-axis and coincides with the q-axis.

  In the present embodiment, the rotor of the rotating electrical machine is particularly configured such that the d-axis magnetic path is magnetically independent via a low permeability layer between a magnetic path including a permanent magnet and a magnetic path not including a permanent magnet. Yes. Of the magnetic resistances forming the d-axis magnetic path, the d-axis combined magnetic resistance Rd, which is the combined magnetic resistance of the magnetic resistance R1 including the permanent magnet and the magnetic resistance R2 not including the permanent magnet, is the q-axis magnetic path. The q-axis magnetic resistance Rq was made smaller.

  Here, the d-axis combined magnetic resistance Rd, which is a combined magnetic resistance of the magnetoresistive R1 including the permanent magnet and the magnetoresistive R2 not including the permanent magnet, is expressed by the following equation (2).

  Then, the following expression (3) is satisfied.

  In this way, the d-axis magnetic path is configured magnetically independently through the low permeability layer in the magnetic path including the permanent magnet and the magnetic path not including the permanent magnet, and satisfies the above equation (3). Since it comprised, the forward collision polarity of Ld> Lq is ensured irrespective of the magnetized state of a magnet.

(Fifth embodiment)
FIG. 7 is a view showing a fifth embodiment of the rotor of the rotating electrical machine according to the present invention.

  In the present embodiment, the rotor of the rotating electrical machine is configured by dividing a magnetic path R1 including a d-axis permanent magnet into a plurality of parts through a low permeability layer. That is, the magnetic path R1 including the permanent magnet is configured by R1_1 and R1_2. The low coercivity permanent magnets 33 are also arranged between a plurality of substantially arc shapes constituting the low magnetic permeability layer.

  According to the present embodiment, since a plurality of d-axis magnetic paths including permanent magnets are arranged in parallel, the electrical angle range in which the magnetomotive force is distributed can be widened when considered on the rotor surface. Therefore, the fundamental wave magnetic flux component included in the magnetomotive force distribution is increased, and the torque is improved.

(Sixth embodiment)
FIG. 8 is a view showing a sixth embodiment of the rotor of the rotating electrical machine according to the present invention.

  In the present embodiment, the rotor of the rotating electrical machine is configured by dividing a magnetic path R1 including a d-axis permanent magnet into a plurality of parts through a low permeability layer. That is, the magnetic path R1 including the permanent magnet is configured by R1_1 and R1_2. The low coercivity permanent magnets 33 are also arranged between a plurality of substantially arc shapes constituting the low magnetic permeability layer. And the permanent magnet which leaves | separates from d axis | shaft has high coercive force and small residual magnetic flux density.

  In the present embodiment, a d-axis magnetic path is configured by a plurality of magnetic circuits including a permanent magnet, and the permanent magnet 31 at the center of the d-axis has a low coercive force and a high residual magnetic flux density. The coercive force is high and the residual magnetic flux density is made small. In this way, since the magnetic flux density distribution waveform on the gap surface 22 approaches a sine wave shape, torque pulsation and vibration noise can be reduced, and iron loss can be reduced. That is, in this embodiment, a plurality of permanent magnets are arranged, and a magnet having a large magnetomotive force at the central portion, a small magnetomotive force at the end portion, and a large coercive force is arranged. By doing so, the gap magnetic flux density distribution on the rotor surface can be formed in a substantially sinusoidal shape, and an electric motor with small torque pulsation and small iron loss can be provided.

  Without being limited to the embodiments described above, various modifications and changes are possible within the scope of the technical idea, and it is obvious that these are also included in the technical scope of the present invention.

  For example, the number of poles, the number of permanent magnets, the number of low permeability layers, and the like may be changed as appropriate.

  The low magnetic permeability layer may be a void (air layer) formed in the rotor core, or the void may be filled with a low magnetic permeability material.

DESCRIPTION OF SYMBOLS 1 Rotor 2 Stator 10 Rotor shaft 20 Rotor core 211-214 Low magnetic permeability layer 31-33 Permanent magnet

Claims (6)

The rotating electric machine including a rotor over the insertion of the permanent magnets to the rotor core,
The rotor core includes a low magnetic permeability layer having a lower magnetic permeability than the rotor core for each fixed mechanical angle.
The permanent magnet forms one magnetic pole with a plurality of permanent magnets provided between the low magnetic permeability layers provided for each of the fixed mechanical angles, and among the plurality of permanent magnets forming the one magnetic pole. At least one of the permanent magnets has a different coercivity than the other permanent magnets,
The low-permeability layer is arranged on the q-axis that is electrically and magnetically orthogonal to the d-axis, which is the direction of magnetic flux generated by the magnetic poles formed by the plurality of permanent magnets, and is convex toward the rotation center of the rotor. Consists of a plurality of substantially arc shapes,
A permanent magnet disposed between a plurality of substantially arcuate shapes constituting the low magnetic permeability layer;
Rotating electric machine characterized by that. In the rotating electrical machine according to claim 1,
Of the magnetoresistives that form the d-axis magnetic path, which is the direction of the magnetic flux created by the magnetic poles formed by the plurality of permanent magnets, a combined magnetoresistor that includes a permanent magnet and a magnetoresistor that does not include a permanent magnet. The d-axis combined magnetoresistance is smaller than the q-axis magnetoresistance of the q-axis magnetic path that is electrically and magnetically orthogonal to the d-axis.
Rotating electric machine characterized by that. The rotating electrical machine according to claim 2,
The magnetoresistive including the permanent magnet is composed of a plurality of magnetoresistors.
Rotating electric machine characterized by that. In the rotary electric machine according to any one of claims 1 to 3 ,
The permanent magnet located farther from the d-axis has higher coercive force and lower residual magnetic flux density.
Rotating electric machine characterized by that. In the rotary electric machine according to any one of claims 1 to 4 ,
A permanent magnet having a lower coercive force among the plurality of permanent magnets forming the one magnetic pole is thicker.
Rotating electric machine characterized by that. In the rotary electric machine according to any one of claims 1 to 5 ,
The low-permeability layer is on the q-axis that is electrically and magnetically orthogonal to the d-axis, which is the direction of the magnetic flux generated by the magnetic poles formed by the plurality of permanent magnets, and in an electrical angle range of 30 to 50 degrees. Arranged and configured with at least one substantially arc shape convex toward the rotation center of the rotor,
Rotating electric machine characterized by that.

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