JP7076188B2 - Variable magnetic force motor - Google Patents

Description

The present invention relates to a variable magnetic force motor.

Conventionally, one magnetic pole is formed by magnetically arranging two permanent magnets having different coercive forces of a low coercive magnet and a high coercive magnet in series, and the rotation is configured by arranging a plurality of the magnetic poles in a rotor. The child structure is known (see Patent Document 1). In the technique disclosed in Patent Document 1, by using this structure, it is possible to improve both the ease of magnetism of the low coercive magnet and the improvement of the demagnetization resistance during load operation.

Japanese Unexamined Patent Publication No. 2008-162201

However, in the above structure, since the low coercive magnets and the high coercive magnets are simply stacked in the magnetic direction, the low coercive magnets are exposed to a non-uniform magnetic field during the load operation. In particular, during high load operation, a demagnetizing field may occur at the circumferential end of the low coercive magnet. If the low coercive magnet is partially demagnetized by this demagnetizing field, a desired torque cannot be obtained, which is a problem.

An object of the present invention is to provide a technique for suppressing unintentional demagnetization of a low coercive magnet during load operation.

The variable magnetic force motor according to the present invention includes a stator having a stator winding for generating a rotating magnetic field and a rotor having a plurality of magnetic poles and arranged via an air gap between the stators. It is a variable magnetic field motor. The magnetic poles of the variable magnetic force motor are a low coercive magnet that can change the residual magnetic flux density by the electromotive force generated by the current flowing in the stator winding, and the residual magnet density by the electromotive force generated by the current flowing in the stator winding. At least two types of magnets of high coercive force magnets that do not change are magnetically arranged in series. The high coercive magnet is arranged closer to the outer periphery of the rotor than the low coercive magnet. A soft magnetic material is interposed between the high coercive magnet and the low coercive magnet. Further, the soft magnetic material has a thickness in the rotor radial direction at the substantially central portion of the magnetic pole thicker than the thickness in the rotor radial direction at the end portion of the magnetic pole, and / or the high coercive magnet has a thickness in the substantially central portion of the magnetic pole. The embedding depth from the outer peripheral surface of the rotor in the above is shallower than the embedding depth at the end of the magnetic pole.

According to the present invention, the soft magnetic material interposed between the high coercive magnet and the low coercive magnet can make the magnetic field applied to the low coercive magnet uniform during the load operation, so that the magnetic field applied to the low coercive magnet can be made uniform during the load operation. It is possible to prevent the low coercive magnet from being unintentionally demagnetized by the demagnetizing magnetic field generated in the magnet.

FIG. 1 is a schematic configuration diagram illustrating the variable magnetic force motor of the first embodiment. FIG. 2 is a diagram for explaining the magnet characteristics of the low coercive magnet. FIG. 3 is a schematic configuration diagram illustrating the variable magnetic force motor of the second embodiment. FIG. 4 is a schematic configuration diagram illustrating the variable magnetic force motor of the third embodiment. FIG. 5 is a schematic configuration diagram illustrating the variable magnetic force motor of the fourth embodiment. FIG. 6 is a diagram for explaining a conventional problem.

[First Embodiment]
FIG. 1 is a configuration diagram of the variable magnetic force motor 100 of the first embodiment as viewed from a cross section perpendicular to the axial direction, and is a diagram showing a part of the entire configuration. The variable magnetic force motor 100 of the present embodiment has a rotor 4 arranged so as to have an air gap 6 between the stator 3 and the stator 3, and a high maintenance magnet magnetically arranged in series in the rotor 4. It is configured to include a magnetic force magnet 1 and a low coercive force magnet 2, and a short-circuit magnetic path 5 interposed between the high coercive force magnet 1 and the low coercive force magnet 2. It should be noted that "magnetically in series" substantially coincides with "in series in the radial direction of the rotor 4" in the present embodiment. The variable magnetic force motor 100 of the present embodiment is premised on being applied as a drive source of an electric vehicle, but is not limited to this, and may be applied to a generator or the like.

The stator 3 includes a ring-shaped stator core 13, a plurality of teeth 9 protruding from the stator core 13 toward the inner peripheral side, and a stator winding wound around the teeth 9 to generate a rotating magnetic field. It consists of a line 12. The stator core 13 is formed of, for example, an electromagnetic steel plate which is a soft magnetic material.

The rotor 4 has a rotor core 14. The rotor core 14 is a so-called laminated structure in which a large number of electromagnetic steel sheets formed by punching a metal steel sheet made of a soft magnetic material having a small coercive force and a high magnetic permeability in an annular shape are laminated in the axial direction. It is formed in a cylindrical shape by a steel plate structure. Further, in the vicinity of the periphery of the rotor core 14 facing the stator core 13 (outer peripheral portion of the rotor core 14), magnetic poles composed of the high coercive magnet 1 and the low coercive magnet 2 are equidistant from each other. Moreover, the magnetic poles adjacent to each other are provided so as to have different polarities. The variable magnetic force motor 100 of the present embodiment has an eight-pole structure as inferred from the partial configuration shown in FIG.

Further, the rotor core 14 has a magnetic barrier 7 which is a space portion formed by punching an electromagnetic steel sheet. The magnetic barrier 7 has a higher magnetic resistance than the magnetic steel sheet. Therefore, the magnetic barrier 7 acts as a magnetic flux barrier against the magnetic flux in the magnetic circuit in which the high coercive magnet 1 and the low coercive magnet 2 are formed on the rotor 4. For example, the magnet magnetic flux generated from the high coercive magnetic force magnet 1 of a certain magnetic pole functions as a barrier of the magnetic path that tends to wrap around to the opposite polarity side of the magnetic pole. The shape of the illustrated magnetic barrier 7 is an example and is not particularly limited.

The high coercive magnet 1 is a permanent magnet having a high coercive force that is not magnetized or demagnetized by the electromotive force of the stator 3 (hereinafter referred to as “stator electromagnetic force”) and the residual magnetic flux density does not change. be. Such a coercive force is, for example, 500 [kA / m] or more. The high coercive magnet 1 is arranged on the outer peripheral side of the rotor 4 in the radial direction with respect to the low coercive magnet 2 at one magnetic pole formed on the rotor 4. In the following description, terms such as "outer peripheral side", "inner peripheral side", "diameter direction", and "circumferential direction" used when explaining the arrangement of each configuration are used with reference to the rotor 4 unless otherwise specified. Be done.

By arranging the high coercive magnet 1 on the outer peripheral side of the low coercive magnet 2 and interposing it between the stator 3 and the low coercive magnet 2, the low coercive magnet 2 unintentionally attaches due to the stator electromotive force. The risk of magnetization or demagnetization can be reduced. Further, in the high coercive magnet 1 of the present embodiment, the depth of embedding from the outer periphery of the two flat plate-shaped permanent magnets in the substantially central portion (the portion near the d-axis) of the magnetic pole is the end portion (q-axis) of the magnetic pole. It is arranged so as to be shallower than the embedding depth from the outer circumference in the side part). The "embedding depth" is the distance from the outer circumference of the rotor 4 to the end portion of the high coercive force magnet 1 on the outer circumference side. However, the "outer circumference of the rotor 4" here is a virtual circle based on the point where the outer circumference of the rotor 4 and the d-axis intersect, and the notch-shaped portion formed on the q-axis is not considered. It shall be.

The bridge-shaped portion of the rotor core 14 formed between the two high coercive magnets 1 and the two low coercive magnets 2 at one magnetic pole is from the viewpoint of the rotational strength of the rotor core 14. It is formed from, and its width and the like are not particularly limited as long as it satisfies a desired rotational strength.

The low coercive force magnet 2 is a permanent magnet having a coercive force to such an extent that the residual magnetic flux density can be changed by the stator magnetomotive force. In the low coercive force magnet 2, two permanent magnets on a substantially flat plate are arranged side by side in a straight line orthogonal to the d-axis. The magnetic characteristics of the low coercive force magnet 2 will be described with reference to FIG.

FIG. 2 is a diagram showing a BH curve showing the magnetic characteristics of a permanent magnet, and is a diagram for explaining an example of the magnetic characteristics of the low coercive force magnet 2. In FIG. 2, the vertical axis represents the magnetic flux density [T] of the low coercive magnet 2, and the horizontal axis represents the strength of the magnetic field (magnetic field strength) [A / m] formed by the current flowing through the stator winding 12. be. The magnetomotive force acting per unit thickness of the low coercive force magnet 2 is the strength of the magnetic field, and the strength of the magnetic field is proportional to the stator magnetomotive force. That is, as the stator magnetomotive force increases in the positive direction, the magnetic field applied to the low coercive magnet 2 becomes stronger, and the magnetic flux density of the low coercive magnet 2 increases accordingly.

As shown in FIG. 2, the magnetic characteristic of the low coercive magnet 2 is an irreversible characteristic, and is selected, for example, according to the magnitude of the current (d-axis current) supplied to the stator winding 12. It has a plurality of magnetization paths c1 to c4. When magnetizing or demagnetizing the low coercive force magnet 2, a pulse of d-axis current is usually supplied to the stator winding 12.

For example, by increasing the height of the pulse of the d-axis current supplied to the stator winding 12 in the positive direction, the low coercive force magnet 2 is magnetized (magnetized) so that its magnetic flux density increases. Ru.

When magnetizing the low coercive magnet 2, one path is selected from the magnetization paths c1 to c4 depending on the height of the pulse of the d-axis current. For example, when the magnetic field created by the pulsed d-axis current supplied to the stator winding 12 is set to be the magnetizing magnetic field H _i1 , the magnetization path c1 is selected. After that, in the selected magnetization path c1, the magnetic flux density [T] of the low coercive magnet 2 fluctuates according to the negative d-axis current by the so-called field weakening control.

On the other hand, by increasing the height of the pulse of the d-axis current supplied to the stator winding 12 in the negative direction, the low coercive force magnet 2 is magnetized (demagnetized) so that its magnetic flux density decreases. Ru. For example, when the low coercive force magnet 2 is demagnetized, the d-axis current supplied to the stator winding 12 is set to be smaller than the value of the negative d-axis current by the field weakening control.

In this way, the magnetic flux density of the low coercive force magnet 2 can be increased or decreased stepwise according to the height of the pulse of the d-axis current supplied to the stator winding 12. That is, the magnetizing amount of the low coercive magnet 2 can be changed stepwise by the d-axis current supplied to the stator winding 12. The coercive force of the low coercive force magnet 2 (absolute value of Hr in the figure) is about 1/5 of the coercive force of a general permanent magnet (that is, the high coercive force magnet 1) used in the IPM motor.

Note that FIG. 2 shows a permanent magnet having four magnetization paths c1 to c4 as an example, but the low coercive force magnet 2 is not limited to this. For example, a permanent magnet having two or three magnetization paths or five or more magnetization paths may be used.

The above are the characteristic magnet characteristics of the low coercive force magnet 2. When a variable magnetic force motor 100 provided with a low coercive magnet 2 having such characteristics is applied to an electric vehicle, the d-axis current supplied to the stator winding 12 while the vehicle is running is controlled to control the electric vehicle. The magnetic force of the low coercive force magnet 2 can be suitably changed according to the traveling state of the magnet. Specifically, for example, in the low rotation region where torque is required, magnetism is performed so that the torque and output are maximized, and in the high rotation region where rotation speed is required, the generation of countercurrent force is suppressed. It is demagnetized to increase the number of revolutions. Further, since the efficiency can be improved in a wide range by changing the magnetic force of the permanent magnet according to the traveling state, the power consumption of the variable magnetic force motor 100 can be suppressed.

The rotary electric machine provided with such a low coercive magnet 2, that is, the variable magnetic force motor 100 of the present embodiment has the characteristic of being able to change the magnetic force of the permanent magnet as described above, and thus has a "variable magnetic force". It is called a motor.

However, when a variable magnetic force motor equipped with a low coercive magnet is applied as a drive source of a vehicle, there is an advantage that the magnetic force can be changed to a desired magnetized state as described above, but a load based on a running requirement is obtained. On the other hand, there is a demerit that the low coercive force magnet is unintentionally demagnetized by the stator electromotive force generated to output the desired torque, and the desired torque may not be obtained.

Here, in the above document, by arranging the high coercive magnets and the low coercive magnets in series in the magnetization direction, the magnetism ease of the low coercive magnets is improved and the demagnetization resistance during load operation is improved. The technology to achieve this is disclosed. The load operation in the present specification is a term indicating an operation for generating torque with respect to a load based on a traveling requirement in the operation of a motor, and is an operation for intentionally demagnetizing a permanent magnet. Is defined as excluding.

However, even in the above-mentioned literature, the above-mentioned demerits cannot be completely solved, and there are the following problems. FIG. 6 is a diagram for explaining a conventional problem. In FIG. 6, for the sake of explanation, the stator 3 and the rotor 4 are drawn in a flat plate shape instead of the original ring shape.

The alternate long and short dash line shown in the figure indicates the stator magnetomotive force, that is, the strength of the magnetic field. As for this one-point chain line, the magnetic field in the magnetization direction (magnetization direction) becomes stronger toward the upper part in the figure, and the magnetic field in the direction opposite to the magnetization direction (demagnetization direction) becomes stronger toward the lower part in the figure. I'm drawing.

As shown by the alternate long and short dash line in FIG. 6, in the place where the phase is shifted by 180 ° from the place where the stator electromotive force in the direction corresponding to the magnetization direction (magnetization direction) of a certain magnetic pole is maximum, the direction opposite to the magnetizing direction. A demagnetizing field occurs (see inside the dotted frame). Especially when a high load is required, the maximum value of the stator magnetomotive force becomes large, so that the demagnetizing field also becomes large. During the load operation, the place where the stator magnetomotive force is maximized rotates and moves along the circumferential direction of the stator 3 in order to generate a desired torque. Therefore, for example, as shown in the figure, when there is a place where the stator magnetomotive force is maximum (N in the figure) ahead of the rotation direction of the rotor, a place out of phase by 180 ° from that place (S in the figure). ) And the circumferential end of the low coercive force magnet 2 may overlap. At that time, the low coercive magnet 2 may be unintentionally demagnetized due to the demagnetizing field generated at the end of the low coercive magnet 2.

That is, in the conventional configuration in which the high coercive magnet 1 and the low coercive magnet 2 are superposed in the magnetization direction and physically vertically stacked, the low coercive magnet 2 is exposed to a non-uniform magnetic field during load operation. Therefore, depending on the load state, a demagnetizing magnetic field may be applied to the end of the low coercive magnet 2. For this reason, conventionally, the low coercive magnet 2 is unintentionally demagnetized by the demagnetizing field generated at the end of the low coercive magnet, especially when a high load is required or when the temperature is high, and a desired torque is obtained. It may not be possible and it becomes a problem.

The present invention solves such a problem. Specifically, the variable magnetic force motor 100 of the first embodiment according to the present invention solves the above problem by providing a short-circuit magnetic path 5 between the high coercive force magnet 1 and the low coercive force magnet 2. Hereinafter, the description will be continued by returning to FIG.

As shown in the figure, the short-circuit magnetic path 5 is provided so as to be interposed between the high coercive magnet 1 and the low coercive magnet 2. The short-circuit magnetic path 5 is a soft magnetic material. As described above, since the rotor core 14 is formed of a soft magnetic material, the short circuit magnetic path 5 may be configured as part of the rotor core 14. However, the short-circuit magnetic path 5 does not necessarily have to be a part of the rotor core 14, and a single soft magnetic material as a separate component is inserted between the high coercive magnet 1 and the low coercive magnet 2 and arranged. It may be configured by

Since the soft magnetic material has a low coercive force and a high magnetic permeability, when the rotor core 14 is viewed as a magnetic circuit, the short-circuit magnetic path 5 provides a magnetic path between the high coercive magnet 1 and the low coercive magnet 2. It acts to short-circuit. Therefore, the stator magnetomotive force generated during the load operation is equalized in the short-circuit magnetic path 5 before being applied to the low coercive magnet 2, so that the demagnetizing field generated at the circumferential end of the low coercive magnet 2 is generated. Can be alleviated. As a result, it is possible to prevent the low coercive magnet 2 from being partially demagnetized by the demagnetizing field generated at the circumferential end of the low coercive magnet 2. As a result, the above-mentioned problems can be solved, and a magnetic flux sufficient to obtain a desired torque can be generated for the low coercive force magnet 2.

Further, as described above, in the high coercive magnet 1 of the present embodiment, the embedding depth of the two flat plate-shaped permanent magnets from the outer periphery at the substantially central portion of the magnetic pole is the embedding depth from the outer periphery at the end of the magnetic pole. It is arranged so that it is shallower than the magnet. In other words, in the variable magnetic force motor 100 of the present embodiment, two flat plate-shaped high coercive magnets 1 are arranged in a substantially triangular shape convex toward the outer circumference. Therefore, since the q-axis magnetic path passing through the outer peripheral side of the magnetic pole is blocked by the convex tip end side portion of the high coercive force magnet 1, the q-axis magnetic flux generated by the load current during the load operation can be reduced. As a result, the power factor during load operation can be improved, and the output torque of the variable magnetic force motor 100 can be further improved.

Since the high coercive magnet 1 of the present embodiment is configured by using a substantially flat plate-shaped permanent magnet, it cuts off the q-axis magnetic path while suppressing an increase in cost, and has a power factor during load operation. Can be improved.

Further, the short-circuit magnetic path 5 is illustrated by arranging the high coercive magnet 1 as described above and arranging the low coercive magnet 2 on the inner peripheral side thereof in a substantially linear shape orthogonal to the d-axis. Shape. That is, in the short-circuit magnetic path 5 of the present embodiment, the thickness in the radial direction at the substantially central portion (approximately on the d-axis) of the magnetic pole is thicker than the thickness in the radial direction at the end portion side (q-axis side) of the magnetic pole. It is configured. As a result, the magnetic flux generated at the circumferential end of the low coercive magnet 2 during load operation can be guided to the substantially central portion of the magnetic pole, so that the demagnetizing field generated at the end of the low coercive magnet 2 is further relaxed. be able to. Therefore, the partial demagnetization of the low coercive force magnet 2 is further suppressed, and the output torque can be further improved.

Further, in the magnetic poles of the rotor 4, the magnetic pole width of the low coercive magnet 2 is configured to be equal to or narrower than the magnetic pole width of the high coercive magnet 1. As a result, it is suppressed that the stator electromotive force is directly applied to the low coercive magnet 2 without passing through the high coercive magnet 1, so that the demagnetizing magnetic field generated at the end of the low coercive magnet 2 is reduced to the high coercive magnet. It can be alleviated more surely by 1. The magnetic pole width here is a linear distance connecting the outer peripheral end portions of the high coercive magnet 1 and the low coercive magnet 2.

With the above configuration, the variable magnetic force motor 100 of the present embodiment can suppress demagnetization generated at the end of the low coercive force magnet 2 during load operation, so that the output torque can be improved as compared with the conventional case.

As described above, in the variable magnetic force motor 100 of the first embodiment, the stator 3 having the stator winding 12 for generating a rotating magnetic field and the stator 3 having a plurality of magnetic poles are interposed via the air gap 6. It is a variable magnetic field motor provided with a rotor 4 arranged therein. The magnetic poles of the variable magnetic force motor 100 are at least two types of magnets, a low coercive magnet 2 in which the residual magnetic flux density changes due to the electromotive force generated by the current flowing in the stator winding 12, and a high coercive magnet 1 in which the residual magnet density does not change. Are magnetically arranged in series. The high coercive magnet 1 is arranged closer to the outer peripheral side of the rotor than the low coercive magnet 2. A soft magnetic material (short-circuit magnetic path 5) is interposed between the high coercive magnet 1 and the low coercive magnet 2. As a result, the soft magnetic material interposed between the high coercive magnet 1 and the low coercive magnet 2 can make the magnetic field applied to the low coercive magnet 2 uniform during the load operation. It is possible to suppress unintentional partial demagnetization of the low coercive force magnet 2 due to the demagnetizing magnetic field generated in the above, and it is possible to improve the output torque.

Further, according to the variable magnetic force motor 100 of the first embodiment, the thickness of the short-circuit magnetic path 5 in the rotor radial direction at the substantially central portion of the magnetic pole is thicker than the thickness in the rotor radial direction at the end portion of the magnetic pole. As a result, the magnetic flux generated at the circumferential end of the low coercive magnet 2 during load operation can be guided to the substantially central portion of the magnetic pole, so that partial demagnetization of the low coercive magnet 2 is further suppressed and the output torque is increased. Can be further improved.

Further, according to the variable magnetic force motor 100 of the first embodiment, in the high coercive force magnet 1, the embedding depth from the outer peripheral surface of the rotor at the substantially central portion of the magnetic pole is shallower than the embedding depth at the end portion of the magnetic pole. As a result, the q-axis magnetic path passing through the outer peripheral side of the magnetic pole can be cut off to reduce the q-axis magnetic flux generated by the load current during load operation, so that the force factor during load operation can be improved and the variable magnetic force can be obtained. The output torque of the motor 100 can be further improved.

Further, according to the variable magnetic force motor 100 of the first embodiment, the high coercive force magnet 1 is composed of at least one substantially flat plate-shaped permanent magnet. As a result, the above effect can be achieved while suppressing an increase in the manufacturing cost of the permanent magnet.

Further, according to the variable magnetic force motor 100 of the first embodiment, the circumferential width of the low coercive magnet 2 constituting the magnetic pole is equal to or equal to the circumferential width of the high coercive magnet 1 constituting the magnetic pole. narrow. As a result, it is suppressed that the stator electromotive force is directly applied to the low coercive magnet 2 without passing through the high coercive magnet 1, so that the demagnetizing magnetic field generated at the end of the low coercive magnet 2 is reduced to the high coercive magnet. It can be alleviated more surely by 1.

[Second Embodiment]
Hereinafter, the second embodiment will be described. The description of the same configuration as that of the first embodiment will be omitted.

FIG. 3 is a schematic configuration diagram illustrating the variable magnetic force motor 200 of the second embodiment. The difference between the variable magnetic force motor 200 of this embodiment and the variable magnetic force motor 100 is the shape of the high coercive force magnet 1.

As shown in the figure, the high coercive force magnet 10 of the present embodiment is composed of a permanent magnet having a substantially arc shape. More specifically, in the variable magnetic force motor 200 of the present embodiment, one magnetic pole is formed by arranging two highly coercive magnets 1 having a substantially arc shape in a semicircular shape convex toward the outer circumference.

In this way, by making the shape of the outer peripheral side of the high coercive magnet 1 substantially arcuate, the interlinkage magnetic flux to the stator, that is, the magnet magnetic flux generated in the air gap 6 can be made closer to the sinusoidal shape. The spatial harmonic component of the magnetic flux of the magnet can be reduced. As a result, iron loss due to the spatial harmonic component of the magnet magnetic flux during load operation can be reduced, so that the efficiency of the variable magnetic force motor 200 can be improved.

As described above, according to the variable magnetic force motor 200 of the second embodiment, the high coercive force magnet 1 is composed of at least one permanent magnet having a substantially arc shape. As a result, the magnetic flux generated in the air gap 6 can be made closer to a sinusoidal shape, so that the spatial harmonic component of the magnetic flux can be reduced. As a result, iron loss due to the spatial harmonic component of the magnetic flux during load operation can be reduced.

[Third Embodiment]
Hereinafter, the third embodiment will be described. The description of the same configuration as that of the first embodiment will be omitted.

FIG. 4 is a schematic configuration diagram illustrating the variable magnetic force motor 300 of the third embodiment. The difference between the variable magnetic force motor 300 of the present embodiment and the variable magnetic force motors 100 and 200 is the arrangement of the high coercive force magnet 1 and the low coercive force magnet 2.

As shown in the figure, the high coercive magnet 1 included in the variable magnetic force motor 300 is configured such that a substantially flat plate-shaped permanent magnet is arranged in a straight line orthogonal to the d-axis on the outer peripheral side of the low coercive magnet 2. The low coercive magnet 2 has a portion on the inner peripheral side of the high coercive magnet 1 in which the embedding depth from the outer periphery in the substantially central portion (the portion near the d-axis) of the magnetic pole is the end portion of the magnetic pole (the portion on the q-axis side). ) Is arranged so as to be deeper than the embedding depth from the outer periphery. In other words, the low coercive magnet 2 of the present embodiment is arranged in a substantially triangular shape convex on the inner peripheral side.

By arranging the low coercive magnet 2 in this way, the surface area of the low coercive magnet 2 seen from the side surface of the rotor 4 can be increased in the circumferential width of one magnetic pole, so that the low coercive magnet 2 can be increased. The magnetic flux of the magnet can be increased. As a result, the magnet magnetic flux generated from the low coercive force magnet 2 can be maximized, so that the output torque of the variable magnetic force motor 300 can be improved.

Since the rotor core 14 is made of a soft magnetic material such as an electromagnetic steel plate as described above, its saturation magnetic flux density is sufficiently larger than the residual magnetic flux densities of the low coercive magnet 2 and the high coercive magnet 1. Therefore, magnetic saturation does not occur even if the magnet magnetic flux of the low coercive force magnet 2 is increased.

As described above, according to the variable magnetic force motor 300 of the third embodiment, in the low coercive force magnet 2, the embedding depth from the outer peripheral surface of the rotor 4 at the substantially central portion of the magnetic pole is larger than the embedding depth at the end portion of the magnetic pole. deep. As a result, the surface area of the low coercive force magnet 2 seen from the side surface of the rotor 4 can be increased in the circumferential width allowed for one magnetic pole, so that the magnet magnetic flux of the low coercive force magnet 2 can be increased. ..

[Fourth Embodiment]
Hereinafter, the fourth embodiment will be described. The description of the same configuration as that of the first embodiment will be omitted.

FIG. 5 is a schematic configuration diagram illustrating the variable magnetic force motor 400 of the fourth embodiment. The variable magnetic force motor 400 of the fourth embodiment is different from the variable magnetic force motors 100 to 300 in that the coercive force of the high coercive magnet 1 and the low coercive magnet 2 and the thicknesses Tb and Tj are limited as follows. It is a point.

The high coercive force magnet 1 of the present embodiment has a coercive force Hcb of 800 kA / m or more. Further, the low coercive force magnet 2 of the present embodiment has a coercive force Hcj of 150 kA / m or less. Here, the coercive forces Hcb and Hcj are defined by the magnetic field strength at which the magnetization becomes zero. That is, the coercive forces Hcb and Hcj are absolute values of the coercive force defined by the magnetic field strength at which the magnetic flux density becomes 0 on the BH curve showing the magnet characteristics (see Hr in FIG. 6). The upper limit of the holding force Hcb is appropriately set according to the desired motor performance. Further, the lower limit of the holding force Hcj may be a value larger than 0.

By defining the coercive force Hcb and Hcj in this way, the residual magnetic flux density of the low coercive force magnet 2 can be changed by the stator electromotive force while maintaining the residual magnetic flux density of the high coercive force magnet 1.

In the present embodiment, the coercive forces Hcb and Hcj of the high coercive force magnet 1 and the low coercive force magnet 2 and the thicknesses Tb and Tj are defined as follows. That is, the coercive force Hcb and Hcj and the respective thicknesses Tb and Tj are the electromotive force [A] of the high coercive force magnet 1 represented by the product of the thickness Tb of the high coercive force magnet 1 and the coercive force Hcb [kA / m]. The value obtained by adding the stator electromotive force [A] at the time of magnetizing is represented by the product of the thickness Tj of the low coercive force magnet 2 and the coercive force Hcj [kA / m] of the low coercive force magnet 2. It is determined to be larger than the motive force [A]. As shown in the figure, the "thickness" here is the thickness of the rotor 4 in the radial direction.

As a result, even if the high coercive force magnet 1 is interposed between the low coercive force magnet 2 and the stator 3, the low coercive force magnet 2 can be reliably magnetized by the stator electromotive force, so that the variable magnetic force motor The output torque of 400 can be improved.

Further, the thickness Tb per magnetic pole of the high coercive magnet 1 is 30% or less of the total thickness retention (Tb + Tj) of the high coercive magnet 1 constituting one magnetic pole and the low coercive magnet 1. As a result, the thickness of the low coercive magnet 2 capable of changing the magnetic force can be sufficiently secured at one magnetic pole, so that the amount of change in the interlinkage magnetic flux of the magnet magnetic flux at one magnetic pole can be sufficiently secured. In this embodiment, one low coercive magnet 2 and a high coercive magnet 1 are arranged side by side in the magnetization direction, but the provisions described in this embodiment relating to the thickness Tb are the high coercive magnet 1 and the low coercive magnet 1. This applies even if two or more coercive magnets 2 are arranged side by side.

As described above, by adopting the above-mentioned configuration, it is possible to sufficiently secure the amount of change in the interlinkage magnetic flux of the magnet magnetic flux while improving the output torque, so that it is possible to reduce the copper loss from low speed to high speed, and especially in the high speed range. Iron loss can be reduced.

More specifically, in the low speed range, the low coercive magnet 2 is magnetized to greatly change the magnetic force, so that the amount of current supplied to the stator 3 required to obtain a desired torque is further reduced. Therefore, copper loss can be reduced. On the other hand, in the high-speed range, the generation of counter electromotive force can be suppressed by demagnetizing the low coercive magnet to change the magnetic force to a small value, so that iron loss can be reduced. As described above, in the variable magnetic force motor 400, the low coercive magnet, which has been a conventional problem, is suppressed from being unintentionally demagnetized, the characteristics of the variable magnetic force motor are sufficiently brought out, and iron loss and copper loss are reduced. Therefore, the output torque can be improved and the efficiency of the motor can be improved.

As described above, according to the variable magnetic force motor 400 of the fourth embodiment, the coercive force Hcb of the high coercive force magnet 1 is 800 kA / m or more, and the coercive force Hcj of the low coercive force magnet 2 is 150 kA / m or less. The sum of the product [A] of the thickness Tb of the high coercive magnet and the coercive force Hcb and the stator electromotive force [A] at the time of magnetizing is the thickness Tj of the low coercive magnet 2 and the coercive force Hcj. Is greater than the product [A] of. As a result, even if the high coercive force magnet 1 is interposed between the low coercive force magnet 2 and the stator 3, the low coercive force magnet 2 can be reliably magnetized by the stator electromotive force, so that the variable magnetic force motor The output torque of 400 can be improved.

Further, according to the variable magnetic force motor 400 of the fourth embodiment, the thickness Tb of the high coercive magnet 1 is the sum of the thickness Tj of the high coercive magnet 1 constituting the magnetic pole and the thickness Tb of the low coercive magnet 2. It is 30% or less with respect to. As a result, the thickness of the low coercive magnet 2 capable of changing the magnetic force can be sufficiently secured, so that the amount of change in the interlinkage magnetic flux of the magnet magnetic flux at one magnetic pole can be sufficiently secured.

Although the embodiments of the present invention have been described above, the above-described embodiments show only a part of the application examples of the present invention, and the technical scope of the present invention is limited to the specific configuration of the above-described embodiments. do not have. In addition, the above embodiments can be combined as appropriate.

For example, one magnetic pole may be formed by combining the arrangement of the low coercive magnet 2 of the third embodiment and the arrangement of the high coercive magnet 1 of the first embodiment.

1 ... High coercive magnet 2 ... Low coercive magnet 3 ... Stator 4 ... Rotor 5 ... Soft magnetic material (short-circuit magnetic path)
6 ... Air gap

Claims (9)

In a variable magnetic force motor comprising a stator having a stator winding for generating a rotating magnetic field and a rotor having a plurality of magnetic poles and arranged between the stators via an air gap.
The magnetic poles have a low coercive force magnet that can change the residual magnetic flux density by the electromotive force generated by the current flowing through the stator winding, and the residual magnet density changes by the electromotive force generated by the current flowing through the stator winding. At least two types of magnets of high coercive force magnets are magnetically arranged in series and configured.
The high coercive magnet is arranged on the outer peripheral side of the rotor with respect to the low coercive magnet.
A soft magnetic material is interposed between the high coercive magnet and the low coercive magnet .
In the soft magnetic material, the thickness in the rotor radial direction at the substantially central portion of the magnetic pole is thicker than the thickness in the rotor radial direction at the end portion of the magnetic pole.
A variable magnetic force motor characterized by that. In a variable magnetic force motor comprising a stator having a stator winding for generating a rotating magnetic field and a rotor having a plurality of magnetic poles and arranged between the stators via an air gap.
The magnetic poles have a low coercive force magnet that can change the residual magnetic flux density by the electromotive force generated by the current flowing through the stator winding, and the residual magnet density changes by the electromotive force generated by the current flowing through the stator winding. At least two types of magnets of high coercive force magnets are magnetically arranged in series and configured.
The high coercive magnet is arranged on the outer peripheral side of the rotor with respect to the low coercive magnet.
A soft magnetic material is interposed between the high coercive magnet and the low coercive magnet .
In the high coercive force magnet, the embedding depth from the outer peripheral surface of the rotor at the substantially central portion of the magnetic pole is shallower than the embedding depth at the end portion of the magnetic pole.
A variable magnetic force motor characterized by that. In a variable magnetic force motor comprising a stator having a stator winding for generating a rotating magnetic field and a rotor having a plurality of magnetic poles and arranged between the stators via an air gap.
The magnetic poles have a low coercive force magnet that can change the residual magnetic flux density by the electromotive force generated by the current flowing through the stator winding, and the residual magnet density changes by the electromotive force generated by the current flowing through the stator winding. At least two types of magnets of high coercive force magnets are magnetically arranged in series and configured.
The high coercive magnet is arranged on the outer peripheral side of the rotor with respect to the low coercive magnet.
A soft magnetic material is interposed between the high coercive magnet and the low coercive magnet .
In the soft magnetic material, the thickness in the rotor radial direction at the substantially central portion of the magnetic pole is thicker than the thickness in the rotor radial direction at the end portion of the magnetic pole.
In the high coercive force magnet, the embedding depth from the outer peripheral surface of the rotor at the substantially central portion of the magnetic pole is shallower than the embedding depth at the end portion of the magnetic pole.
A variable magnetic force motor characterized by that. In the low coercive magnet, the embedding depth from the outer peripheral surface of the rotor at the substantially central portion of the magnetic pole is deeper than the embedding depth at the end portion of the magnetic pole.
The variable magnetic force motor according to any one of claims 1 to 3. The high coercive force magnet is composed of at least one substantially flat plate-shaped permanent magnet.
The variable magnetic force motor according to any one of claims 1 to 4. The high coercive force magnet is composed of at least one permanent magnet having a substantially arc shape.
The variable magnetic force motor according to any one of claims 1 to 5. The circumferential width of the low coercive magnet constituting the magnetic pole is equal to or narrower than the circumferential width of the high coercive magnet constituting the magnetic pole.
The variable magnetic force motor according to any one of claims 1 to 6. The coercive force Hcb of the high coercive force magnet is 800 kA / m or more.
The coercive force Hcj of the low coercive force magnet is 150 kA / m or less.
The sum of the product of the thickness of the high coercive magnet and the coercive force Hcb and the stator electromotive force at the time of magnetism is larger than the product of the thickness of the low coercive magnet and the coercive force Hcj. ,
The variable magnetic force motor according to any one of claims 1 to 7. The thickness of the high coercive magnet is 30% or less with respect to the total thickness of the high coercive magnet constituting the magnetic pole and the low coercive magnet.
The variable magnetic force motor according to any one of claims 1 to 8.

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