JP7455697B2 - rotor of rotating electric machine - Google Patents

Description

Embodiments of the present invention relate to a rotor of a rotating electrical machine.

A synchronous reluctance motor (SynRM) is provided as a rotating electric machine. The rotor of this reluctance motor is provided with a flux barrier made of a non-magnetic material. Torque is generated by obtaining saliency due to the difference in magnetic permeability between the rotor core and the flux barrier. Air is a typical example of a non-magnetic material (having a relative magnetic permeability of approximately 1). For this reason, in practical examples of inverter-driven synchronous reluctance motors, the flux barrier is often made hollow (not filled with anything).

On the other hand, although aluminum and copper are also nonmagnetic materials, they are also electrical conductors. Therefore, a secondary conductor can be formed by filling the flux barrier with aluminum, copper, or the like. In other words, in an asynchronous state (a state in which the rotational speed of the stator's rotating magnetic field and the physical rotational speed of the rotor do not match, and the rotor is slipping), induced torque is generated, so it is possible to It becomes possible to realize a line-start synchronous reluctance motor (LS-SynRM).
A self-starting synchronous reluctance motor does not require a drive inverter, so it can reduce costs when viewed as a motor drive system. Furthermore, since there is no loss such as switching loss that occurs in the converter, the efficiency of the entire system can be improved.

Patent No. 4098939 Patent No. 4588255 Japanese Patent Application Publication No. 5-91684 Patent No. 5411883

"Dynamic characteristics of hysteresis motor", Hitachi Review, May 1969 issue "Hysteresis Motor", Electrical Society Journal, Vol. 99, No. 4, 1979

As described above, self-starting synchronous reluctance motors have excellent properties that allow them to achieve both low cost and high efficiency, but there are problems with starting characteristics. A self-starting synchronous reluctance motor rotates at a synchronous speed during steady operation, with zero slippage. Acceleration from a state of slippage to synchronous speed is called synchronous pull-in. Whether synchronous pull-in is possible depends on the moment of inertia, and even if the load torque is below the rated torque, if the moment of inertia is large, synchronous pull-in may not be possible. For example, the moment of inertia of a fan or blower connected as a load is several to several tens of times larger than the moment of inertia of the motor itself. Therefore, whether a motor to which a fan or blower is connected may be synchronously pulled in may be a problem. The maximum value of the load inertia moment that can be synchronously pulled in (hereinafter referred to as allowable inertia moment) can be improved by increasing the induction torque.

In order to increase the induced torque, it is necessary to increase the cross-sectional area of the secondary conductor to decrease the secondary resistance. However, when the area of the secondary conductor is increased, the area of the core portion becomes relatively smaller, the magnetic balance of the rotor is lost, and the saliency of the rotor is reduced. That is, even if synchronous pull-in is possible, the torque and power factor during steady operation are low, making it difficult to fully demonstrate the performance as a synchronous reluctance motor.
The present invention has been made in view of the above points, and an object thereof is to provide a rotor for a rotating electrical machine that has improved starting characteristics without reducing reluctance torque.

According to the embodiment, the rotor of the rotating electric machine includes a shaft rotatable around a central axis;
The rotor core includes a plurality of magnetic poles arranged in a circumferential direction around the central axis and is fixed to the shaft. The magnetic poles of the rotor core are formed with a plurality of layers of flux barriers extending from one location to another on the outer circumferential surface of the rotor core, arranged so as to pass through predetermined axes passing through the central axis. , the flux barrier includes a first bridge portion and a second bridge portion forming a part of the outer peripheral surface of the rotor core at both ends of the flux barrier in the longitudinal direction; and a first bridge portion and a second bridge portion. and a void layer located between. The at least one layer of flux barrier has a hard magnetic region whose magnetization can be reversed, which is formed of a hard magnetic material and filled in at least a portion of the gap layer.

FIG. 1 is a cross-sectional view of a rotating electric machine according to a first embodiment. FIG. 2 is an enlarged cross-sectional view of one magnetic pole portion of the rotor of the rotating electric machine. FIG. 3A is a diagram schematically showing first temporal changes in magnetic field vectors and magnetization vectors in a hard magnetic region. FIG. 3B is a diagram schematically showing a second temporal change in the magnetic field vector and magnetization vector in the hard magnetic region. FIG. 3C is a diagram schematically showing a third time change of the magnetic field vector and magnetization vector in the hard magnetic region. FIG. 3D is a diagram schematically showing the fourth time change of the magnetic field vector and magnetization vector in the hard magnetic region. FIG. 4 is a diagram showing temporal changes in magnetic field and magnetization in a hard magnetic region. FIG. 5 is a diagram showing an analysis result of torque generated during asynchronous operation. FIG. 6 is a diagram showing an example of an armature current waveform at the time of starting. FIG. 7 is a cross-sectional view showing one magnetic pole portion of a rotor of a rotating electric machine according to a first modification. FIG. 8 is a sectional view showing one magnetic pole portion of a rotor of a rotating electrical machine according to a second modification. FIG. 9 is a sectional view showing one magnetic pole portion of a rotor of a rotating electric machine according to a third modification. FIG. 10 is a sectional view showing one magnetic pole portion of a rotor of a rotating electric machine according to a second embodiment. FIG. 11 is a sectional view showing one magnetic pole portion of a rotor of a rotating electric machine according to a third embodiment.

Embodiments will be described below with reference to the drawings. The disclosure is merely an example, and any modifications that can be easily made by those skilled in the art while maintaining the spirit of the invention are naturally included within the scope of the present invention. In addition, in order to make the explanation clearer, the drawings may schematically represent the width, thickness, shape, etc. of each part compared to the actual aspect, but these are only examples, and the interpretation of the present invention is It is not limited. In addition, in this specification and each figure, the same elements as those described above with respect to the previously shown figures are denoted by the same reference numerals, and detailed explanations may be omitted as appropriate.

(First embodiment)
FIG. 1 is a cross-sectional view of a rotating electrical machine according to a first embodiment, and FIG. 2 is an enlarged cross-sectional view of one magnetic pole of a rotor.
As shown in FIG. 1, the rotating electrical machine 10 is configured as, for example, an inner rotor type rotating electrical machine, and includes an annular or cylindrical stator 12 supported by a fixed frame (not shown), and a center axis C inside the stator. The rotor 14 is rotatably supported around the stator 12 and coaxially with the stator 12. In the embodiment, the rotating electric machine 10 constitutes a self-starting reluctance motor (LS-SynRM).

The stator 12 includes a cylindrical stator core 16 and an armature winding 18 wound around the stator core 16. The stator core 16 is constructed by concentrically laminating a large number of annular electromagnetic steel plates made of magnetic material, such as silicon steel. The stator core 16 can also be formed by pressure molding soft magnetic powder. The stator core 16 has an annular yoke portion 17 and a plurality of stator cores extending from the inner circumference of the yoke portion 17 toward the central axis C and arranged at equal intervals in the circumferential direction of the yoke portion 17 (for example, in this embodiment, 36) stator teeth 21. The teeth 21 are formed to have a substantially rectangular cross section. The extending ends of the teeth 21 face the rotor 14 with a predetermined gap therebetween.
Slots 20 are formed between adjacent teeth 21, respectively. The plurality of slots 20 are arranged at equal intervals in the circumferential direction. Each slot 20 opens in the inner circumferential surface of the stator core 16 and extends radially from the inner circumferential surface. Further, each slot 20 extends over the entire length of the stator core 16 in the axial direction.

Armature windings 18 are embedded in the plurality of slots 20 and are wound around each stator tooth 21 via an insulator or insulation coating (not shown). The armature winding 18 is divided into three phases (U phase, V phase, and W phase). By passing current through the armature winding 18 from the three-phase AC power supply, a predetermined flux linkage is formed in the stator 12 (stator teeth 21).
Note that an insulator having insulation properties may be attached to the stator core 16, or the entire outer surface of the stator core 16 may be covered with an insulating coating (neither is shown).

The rotor 14 has a cylindrical shaft (rotation shaft) 22 and a cylindrical rotor core 24 coaxially fixed to substantially the center of the shaft 22 in the axial direction. The shaft 22 is rotatably supported around the central axis C by a bearing (not shown). The rotor 14 is coaxially arranged inside the stator 12 with a slight gap (air gap) G therebetween. That is, the outer circumferential surface of the rotor core 24 faces the inner circumferential surface of the stator 12 (the tip surface of the stator teeth 21) with a slight gap G therebetween. The rotor core 24 has an inner hole 25 formed coaxially with the central axis C. The shaft 22 is inserted into and fitted into the inner hole 25 and extends coaxially with the rotor core 24 . The rotor core 24 is configured as a laminate in which a large number of annular electromagnetic steel plates made of magnetic material, such as silicon steel, are laminated concentrically. The rotor core 24 can also be formed by pressure molding soft magnetic powder.

In this embodiment, the rotor 14 has multiple magnetic poles, for example, four magnetic poles. In the rotor core 24, the direction perpendicular to the center axis C is called the radial direction, and the direction around the center axis C is called the circumferential direction. In addition, the axis that passes through the center axis C and the boundary between adjacent magnetic poles and extends in the radial or radial direction with respect to the center axis C is the q axis, and the axis electrically and magnetically perpendicular to the q axis is the d axis. It is called. Here, the direction in which the interlinkage magnetic flux formed by the stator 12 tends to flow is defined as the q-axis. The d-axis and the q-axis are provided alternately in the circumferential direction of the rotor core 24 and at a predetermined phase. One magnetic pole of the rotor core 24 refers to the area between two adjacent q-axes (circumferential angle area of 1/4 circumference). The circumferential center of one magnetic pole is the d-axis.

FIG. 2 is a cross-sectional view showing one magnetic pole portion of the rotor, that is, a circumferential angle region of 1/4 circumference. As shown in FIGS. 1 and 2, the rotor core 24 has a plurality of layers, for example, four layers of flux barriers 30a, 30b, 30c, and 30d for each magnetic pole. In each magnetic pole, four layers of flux barriers 30a to 30d are arranged in order from the central axis C side to the outer circumferential surface side at intervals from each other in the radial direction (here, the d-axis direction) of the rotor core 24. ing. That is, each of the flux barriers 30a to 30d extends from a certain point on the outer circumferential surface of the rotor core 24 through the d-axis to another point on the outer circumferential surface, and curves convexly toward the central axis C. ing. The plurality of flux barriers 30a to 30d are formed between the plurality of magnetic paths through which the magnetic flux formed by the stator 12 passes, and partition each magnetic path.

In this embodiment, each of the flux barriers 30a to 30d is formed of a void layer 32 extending in a substantially hyperbolic shape centered on the d-axis, and an iron core located between one end of the void layer 32 and the outer peripheral surface. It has a thin connecting portion (first bridge portion) 34a and a thin connecting portion (second bridge portion) 34b formed of an iron core located between the other end of the void layer 32 and the outer peripheral surface. The first bridge portion 34a and the second bridge portion 34b have a radial width WO. The first bridge portion 34a and the second bridge portion 34b play a role of coupling (connecting) the rotor cores 24 separated by the gap layer 32 of each flux barrier 30a to 30d. Note that the radial width WO of the first bridge portion 34a and the second bridge portion 34b belonging to each layer is not limited to constant, and may be non-uniform.

For example, in the flux barrier 30a provided on the innermost side, one end of the void layer 32 is located near the outer peripheral surface and near one of the q-axes, and the other end of the void layer 32 is located near the outer peripheral surface. , and is located near the other q-axis. The void layer 32 is curved in a convex shape from the outer circumferential side toward the center axis C radially inward along the q-axis from the one end to the other end such that the circumferential center is located most radially inward. It has an approximately arcuate cross-sectional shape. In one example, the void layer 32 is formed in a band shape having a constant width. Note that the shape of each void layer 32 is not limited to a circular arc shape, but may be a hyperbolic shape or a convex shape such as a U-shape. Further, the width of the void layer 32 is not limited to a constant width, and may be formed to have a different width depending on the region.
The second layer, the third layer, and the outermost layer flux barriers 30b, 30c, and 30d are arranged at intervals in the d-axis direction with respect to the innermost layer flux barrier 30a. The flux barrier is not limited to four layers, but may be formed in a single layer, two layers, three layers, or five or more layers. Further, the void layer 32 of each flux barrier is not limited to one continuous layer, but may be a plurality of divided void layers.

Each gap layer 32 is filled with a non-magnetic insulator (air, resin, etc.) to form a barrier region 40 having a lower magnetic permeability than the core portion. The barrier region 40 has a property that allows magnetic flux to pass through it more easily (obstructs the flow of magnetic flux) than the magnetic path.
In the rotor core 24, the above-mentioned q-axis corresponds to the direction in which the flow of magnetic flux is not hindered by the barrier region 40. That is, a positive magnetic potential (for example, bringing the N pole of a magnet closer to each other) is applied to a certain circumferential angular position A on the outer circumferential surface of the rotor core 24, and the magnetic potential is shifted by one pole (90 degrees in the case of this example). When a negative magnetic potential is applied to the circumferential angle position B (for example, by bringing the S pole of the magnet closer together) and the position A is shifted in the circumferential direction, the magnetic flux moves from the central axis C where the most magnetic flux flows toward position A. The direction is defined as the q-axis. On the other hand, the d-axis, which is magnetically perpendicular to the q-axis, corresponds to the direction in which the flow of magnetic flux is blocked by the barrier region 40.

Since the magnetic flux in the d-axis direction is blocked by the barrier region 40, magnetic anisotropy appears in the rotor core 24 in both the d-axis direction and the q-axis direction. This creates a reluctance torque, and the reluctance motor 10 produces a constant torque at synchronous speed. On the other hand, at asynchronous speeds, the reluctance torque pulsates and the average value is zero.

As shown in FIGS. 1 and 2, according to the first embodiment, in at least one layer of the flux barriers 30a to 30d, for example, in the three layers of flux barriers 30a, 30b, and 30c on the inner peripheral side, each barrier region 40 At least a portion, for example the longitudinal center portion, is replaced by a hard magnetic region 42 filled with hard magnetic material. The hard magnetic material is a material that constitutes a permanent magnet, and includes, for example, a rare earth magnet, a ferrite magnet, an alnico magnet, a samarium iron cobalt magnet, and the like. The hard magnetic region 42 may be magnetized, not magnetized, or incompletely magnetized. The hard magnetic region 42 is arranged to cross the d-axis and has a predetermined length in the longitudinal direction. In this embodiment, the hard magnetic regions 42 are provided symmetrically with respect to the d-axis. In the flux barriers 30a, 30b, and 30c, the regions excluding the hard magnetic region 42 are the barrier region 40 and the bridge portions 34a, 34b.
The easy axis direction of magnetization of each hard magnetic region 42 is approximately parallel to the d-axis direction. Note that the recoil relative magnetic permeability of the general hard magnetic material described above is approximately 1. That is, the magnetic resistance of the hard magnetic material is sufficiently larger than that of the core portion of the rotor core 24, and has a function as a barrier region. Therefore, even if part of the barrier region 40 is replaced with the hard magnetic region 42, the original properties of the synchronous reluctance motor (efficiency, power factor, etc.) are not impaired.

During asynchronous operation such as when a rotating electric machine is started, a difference occurs between the synchronous speed and the physical speed of the rotor 14, and an alternating magnetic field is applied to the rotor 14. The magnetic flux density of the hard magnetic region 42 changes irreversibly due to the hysteresis magnetic property of the hard magnetic material. Irreversible changes create a phase difference between the magnetic field and magnetization, resulting in hysteresis torque.

3A, 3B, 3C, and 3D are diagrams respectively showing the results of simulating the magnetization reversal of the hard magnetic region 42 in the first embodiment by magnetic field analysis using the finite element method. A three-phase alternating current with a constant effective value was passed through the armature winding 18 to generate a rotating magnetic field.
State 1 shown in FIG. 3A is a state in which the magnetic field applied to the hard magnetic material is approximately zero. At this time, the magnetization of each hard magnetic region 42 is directed in the positive direction of the d-axis (upward in the figure).
State 2 shown in FIG. 3B is a state when the phase of the three-phase alternating current changes after a short period of time and a magnetic field is generated in the negative direction of the d-axis (downward in the figure). Even in this state 2, the magnetization is generally in the positive direction of the d-axis. Thereafter, as time passes, the state changes sequentially to state 3 shown in FIG. 3C and state 4 shown in FIG. 3D, and as the magnetic field in the negative direction becomes larger, the magnetization also changes in the negative direction.

In this way, the magnetization of the hard magnetic region 42 changes a little later than the change in the magnetic field.
FIG. 4 is a diagram showing changes in magnetic field and magnetization over time. It can also be seen from FIG. 4 that the change in magnetization lags behind the change in magnetic field.

FIG. 5 is a diagram showing an analysis result of torque generated during asynchronous operation.
In FIG. 5, (FB+Mag) indicates an analysis result simulating the reluctance motor 10 according to the first embodiment. That is, the flux barrier is composed of the barrier region 40 and the hard magnetic region 42. Note that the average torque in the figure is an average value per period of electrical angle. It can be seen that in the reluctance motor 10 according to the first embodiment, almost constant torque can be obtained regardless of slippage.
In FIG. 5, FB indicates an analysis result when a general synchronous reluctance motor is simulated. That is, in a typical synchronous reluctance motor, the flux barrier consists of only a barrier region and does not have a hard magnetic region. In this reluctance motor, the average torque for one period of electrical angle is zero, and it can be confirmed that acceleration (starting) is not possible.

On the other hand, a technique is known that improves efficiency and power factor by inserting permanent magnets into a synchronous reluctance motor. These motors use magnets made of a hard magnetic material with a very high coercive force Hc so that the permanent magnets do not undergo magnetization reversal (irreversible demagnetization) under any operating conditions. In contrast, in the reluctance motor according to the present embodiment, the magnetization of the hard magnetic material forming the hard magnetic region 42 is assumed to be reversed during asynchronous operation.

電機子巻線１８の内の１相（Ｕ相）に流れる電流をｉuとすすると、Ｕ相電流が作る起磁力Ｆuは次のようになる。

Ｖ相とＷ相についても同様である。これらをベクトルとして足し合わせると、実効値Ｉaの３相電流が作る起磁力Ｆは次のように計算できる。

１極あたりのフラックスバリア３０ａの厚み（フラックスバリアのｄ軸方向の幅）の総和をｔmとすると、硬磁性領域４２に発生する磁界Ｈは次のように計算できる。

Ｈc＜Ｈとなった時、硬磁性領域４２の磁化の反転が発生する。したがって、本実施形態に係る自己始動形の同期リラクタンスモータ１０は、定格電圧で始動した場合に流れる３相電流の実効値の最大値をＩmaxとした時、以下の条件が成立するモータである。

If the number of series conductors in the slot 20 is Nt, the number of slots in the stator is Ns, the number of poles is P, the number of parallel circuits in the armature winding is Nc, and the total thickness of the hard magnetic region per pole is tm, The number of slots corresponding to each phase per pole (number of slots per pole and phase) Ta is as follows.

Assuming that the current flowing in one phase (U phase) of the armature winding 18 is iu, the magnetomotive force Fu generated by the U phase current is as follows.

The same applies to the V phase and W phase. By adding these as vectors, the magnetomotive force F generated by the three-phase current of effective value Ia can be calculated as follows.

If the total thickness of the flux barrier 30a per pole (the width of the flux barrier in the d-axis direction) is tm, the magnetic field H generated in the hard magnetic region 42 can be calculated as follows.

When Hc<H, the magnetization of the hard magnetic region 42 is reversed. Therefore, the self-starting synchronous reluctance motor 10 according to the present embodiment is a motor that satisfies the following conditions, where Imax is the maximum value of the effective value of the three-phase current that flows when started at the rated voltage.

と計算できる。なお、Ｕ相、Ｖ相、Ｗ相電流の瞬時値をｉu(t)、ｉv(t)、ｉw(t)とすると、３相電流の包絡線Ａ(t)は、次のように計算できる。

FIG. 6 is a diagram showing an example of the current waveform of the armature winding current at the time of starting. As shown in the figure, the maximum value of the envelope of the three-phase current is 114A. Therefore, in this example, the maximum value Imax is

It can be calculated as follows. If the instantaneous values of the U-phase, V-phase, and W-phase currents are iu(t), iv(t), and iw(t), the envelope A(t) of the three-phase current can be calculated as follows. .

According to the self-starting synchronous reluctance motor 10 according to the first embodiment configured as described above, a plurality of layers of flux barriers 30a to 30d are formed on each magnetic pole of the rotor core 24, and each flux barrier has , a plurality of bridge portions 34a, 34b are formed, and a barrier region 40 is formed between the bridge portions. The barrier region 40 is filled with a non-magnetic insulator (air, resin, etc.) to prevent the flow of magnetic flux. In at least one layer of flux barrier, at least a portion of the barrier region 40 is filled with a hard magnetic material (rare earth magnet, ferrite magnet, alnico magnet, samarium iron cobalt magnet, etc.) to form a hard magnetic region 42 . The hard magnetic region 42 obstructs the flow of magnetic flux, and when out of synchronization, the magnetization of the hard magnetic material is reversed (irreversible demagnetization) to generate hysteresis torque. Thereby, even when the torque and moment of inertia of the load are large, synchronous pull-in can be performed. In particular, if the hysteresis torque is set larger than the load torque, the restriction of the allowable load inertia moment will be released, and the range of application of the present reluctance motor will be greatly expanded. As described above, by utilizing the above-described technology, a self-starting type synchronous reluctance motor with improved startability and its rotor can be obtained.

Next, rotating electric machines according to modified examples and other embodiments will be described. In the modified examples and other embodiments described below, parts that are the same as those in the first embodiment described above are given the same reference numerals, detailed explanations thereof will be omitted or simplified, and the parts that are different from the first embodiment will be omitted or simplified. I will mainly explain the parts.
(First modification)
FIG. 7 is a sectional view showing one magnetic pole portion of a rotor of a rotating electric machine according to a first modification.
As illustrated, the hard magnetic regions 42 of the flux barriers 30a, 30b, and 30c may be formed of a flat hard magnetic material inserted into the gap layer 32.

(Second modification)
FIG. 8 is a cross-sectional view showing one magnetic pole portion of a rotor of a rotating electrical machine according to a second modification.
As shown in the figure, center bridges 44 and 45 formed of iron core parts may be provided at the circumferential center of the flux barriers 30a and 30b, respectively. In this modification, the center bridges 44 and 45 are arranged on the d-axis. By providing the center bridges 44 and 45, the mechanical strength of the rotor core 24 against centrifugal force is improved, and the rotor core 24 can be operated at a higher rotation speed.
In the flux barriers 30b, 30c, two or more hard magnetic regions 42 are provided in the barrier region. The hard magnetic regions 42 are provided between one end of the flux barrier in the longitudinal direction and the central portion, and between the other end of the flux barrier in the longitudinal direction and the central portion.
The number of hard magnetic regions 42 to be installed is not limited to two, but may be three or more, and the installation positions are not limited to the above and can be arbitrarily selected.

(Third modification)
FIG. 9 is a sectional view showing one magnetic pole portion of a rotor of a rotating electric machine according to a third modification.
As shown in the figure, three layers of flux barriers 30a, 30b, and 30c are provided on each magnetic pole of the rotor core 24. The three layers of flux barriers 30a, 30b, and 30c are arranged at intervals in the radial direction of the rotor core 24 in order from the central axis C side to the outer peripheral surface side. Each of the flux barriers 30a, 30b, and 30c extends from a certain point on the outer circumferential surface of the rotor core 24 through the d-axis to another point on the outer circumferential surface, and curves convexly toward the central axis C. ing. The plurality of flux barriers 30a, 30b, and 30c are formed between the plurality of magnetic paths through which the magnetic flux formed by the stator 12 passes, and partition each magnetic path.

Each of the flux barriers 30a, 30b, and 30c includes a void layer 32 extending in a substantially hyperbolic shape centered on the d-axis, and a first bridge formed of an iron core located between one end of the void layer 32 and the outer peripheral surface. portion 34a, and a second bridge portion 34b formed of an iron core located between the other end of the void layer 32 and the outer peripheral surface. The first bridge portion 34a and the second bridge portion 34b have a radial width WO. The first bridge portion 34a and the second bridge portion 34b play a role of coupling (connecting) the rotor cores 24 separated by the gap layer 32 of each flux barrier 30a, 30b, 30c. Note that the radial width WO of the first bridge portion 34a and the second bridge portion 34b belonging to each layer is not limited to a constant value, and may be non-uniform.

For example, in the flux barrier 30a provided on the innermost side, one end of the void layer 32 is located near the outer peripheral surface and near one of the q-axes, and the other end of the void layer 32 is located near the outer peripheral surface. , and is located near the other q-axis. The void layer 32 is curved in a convex shape from the outer circumferential side toward the center axis C radially inward along the q-axis from the one end to the other end such that the circumferential center is located most radially inward. It has a hyperbolic cross-sectional shape. Note that the shape of each void layer 32 is not limited to a hyperbolic shape, but may be a convex shape such as an arc shape or a U-shape.
The second and third layer flux barriers 30b and 30c are arranged at intervals in the d-axis direction with respect to the innermost layer flux barrier 30a. The flux barrier is not limited to three layers, but may be a single layer, two layers, or four or more layers.

Each gap layer 32 is filled with a non-magnetic insulator (air, resin, etc.) to form a barrier region 40 having a lower magnetic permeability than the core portion. In the three-layer flux barrier 30a, 30b, 30c, at least a portion of each barrier region 40, for example, the central portion in the longitudinal direction, is replaced by a hard magnetic region 42 filled with a hard magnetic material. The hard magnetic material is a material that constitutes a permanent magnet, and includes, for example, a rare earth magnet, a ferrite magnet, an alnico magnet, a samarium iron cobalt magnet, and the like. The hard magnetic region 42 may be magnetized, not magnetized, or incompletely magnetized. The hard magnetic region 42 is arranged to cross the d-axis and has a predetermined length in the longitudinal direction. In this embodiment, the hard magnetic regions 42 are provided symmetrically with respect to the d-axis.

According to the third modification, two bridges 46a, 46b formed of iron core parts are provided in the longitudinal center of each flux barrier 30a, 30b, 30c. Each of the bridges 46a and 46b extends radially across the void layer 32 and connects the core portion located on the inner peripheral side and the iron core portion located on the outer peripheral side of each flux barrier. The bridges 46a, 46b are arranged on both sides of the hard magnetic region 42 in the longitudinal direction. In one example, bridges 46a and 46b are arranged symmetrically with respect to the d-axis. By providing the bridges 46a and 46b, the mechanical strength of the rotor core 24 against centrifugal force is further improved, and the rotor core 24 can be operated at a higher rotation speed.
Note that the number of bridges is not limited to two, but may be three or more, and the installation positions are not limited to the above and can be arbitrarily selected.
In the second modification described above, in order to maintain mechanical balance, it was necessary to arrange the hard magnetic region 42 at a symmetrical position with respect to the d-axis, and it was necessary to divide the hard magnetic material into a large number of parts. On the other hand, in the third modification, a high-strength rotor 14 that maintains mechanical balance can be realized without increasing the number of divided hard magnetic bodies.

(Second embodiment)
FIG. 10 is a sectional view showing one magnetic pole portion of a rotor of a rotating electric machine according to a second embodiment.
In the first embodiment, the flux barrier is constituted by the barrier region 40 and/or the hard magnetic region 42. According to the second embodiment, a part or all of the barrier region is filled with a nonmagnetic conductor, and each constitutes a conductive region (secondary conductor) 50. In the illustrated example, all barrier regions are replaced with conductive regions 50. Copper, aluminum, stainless steel, etc. can be used as the nonmagnetic conductor.
These conductive regions 50 are short-circuited to each other by a short-circuit member (for example, an end ring), not shown, provided at one end of the rotor core 24 in the axial direction, and constitute a secondary winding.

By making the barrier region the conductive region 50, an eddy current is generated in the conductive region 50 during asynchronous operation, and an induced torque is obtained. Similar to the first embodiment, since hysteresis torque is generated in the hard magnetic region 42 of each flux barrier, a larger starting torque can be obtained. Note that the conductive region 50 for generating induced torque is preferably provided in a region close to the outer periphery of the rotor core 24.
In FIG. 5 described above, (Cnd+Mag) indicates an analysis result simulating the reluctance motor 10 according to the second embodiment. That is, the flux barrier is composed of a conductive region and a hard magnetic region. It can be seen from FIG. 5 that the reluctance motor 10 according to the second embodiment has a larger torque than the reluctance motor (FB+Mag) according to the first embodiment.

In Fig. 5, Cnd indicates the analysis result when a reluctance motor (self-starting synchronous reluctance motor using only induction torque) is simulated in which all barrier regions and hard magnetic regions are replaced with conductive regions. . In this motor, as the slip approaches zero, the torque also approaches zero. On the other hand, in the reluctance motor 10 according to the second embodiment, as shown by (Cnd+Mag), hysteresis torque is obtained even when the slip becomes zero, so the torque approaches a value larger than zero. There is.
As described above, the reluctance motor according to the second embodiment can obtain a larger starting torque than the reluctance motor according to the first embodiment, and also overcomes the drawbacks of the conventional self-starting type synchronous reluctance motor. be able to. Also, in the second embodiment, as in the first embodiment, a self-starting type synchronous reluctance motor and a rotor that can be synchronously pulled in even when the load torque and moment of inertia are large and have improved starting performance. is obtained.

(Third embodiment)
FIG. 11 is a sectional view showing one magnetic pole portion of a rotor of a rotating electric machine according to a third embodiment.
In the third embodiment, the number of magnetic poles of the rotor 14 of the reluctance motor 10 is set to two. As shown in FIG. 11, the rotor core 24 has a plurality of layers, for example, three layers of flux barriers 30a, 30b, and 30c for each magnetic pole. In each magnetic pole, three layers of flux barriers 30a, 30b, 30c are arranged in order from the central axis C side to the outer circumferential surface side at intervals from each other in the radial direction (here, the d-axis direction) of the rotor core 24. It is being

The first layer flux barrier 30a located on the innermost side extends approximately linearly from a certain point on the outer circumferential surface of the rotor core 24 to another point on the outer circumferential surface approximately 180 degrees apart through the d-axis. There is. The flux barrier 30a includes a substantially linear void layer 32, a first bridge portion 34a formed of an iron core located between one end of the void layer 32 in the longitudinal direction and the outer peripheral surface, and a first bridge portion 34a formed of an iron core located between one longitudinal end of the void layer 32 and the outer peripheral surface. It has a second bridge portion 34b formed of an iron core located between the other end and the outer peripheral surface. A central portion in the longitudinal direction of the void layer 32 is curved convexly toward the outer peripheral surface so as to avoid the shaft 22.

The second layer flux barrier 30b is provided at a predetermined distance in the radial direction from the first layer flux barrier 30a. The flux barrier 30b extends substantially linearly from a certain point on the outer circumferential surface of the rotor core 24 to another point on the outer circumferential surface that is approximately 180 degrees apart through the d-axis. The flux barrier 30b includes a generally linear void layer 32, a first bridge portion 34a formed of an iron core located between one end of the void layer 32 in the longitudinal direction and the outer peripheral surface, and a first bridge portion 34a formed of an iron core located between one longitudinal end of the void layer 32 and the outer peripheral surface. It has a second bridge portion 34b formed of an iron core located between the other end and the outer peripheral surface. A central portion in the longitudinal direction of the void layer 32 is curved in a convex manner toward the outer peripheral surface.

The third layer flux barrier 30c is provided radially outward, that is, on the outer peripheral surface side, with a predetermined distance from the second layer flux barrier 30a. The flux barrier 30c extends substantially linearly from a certain point on the outer circumferential surface of the rotor core 24 to another point on the outer circumferential surface that is approximately 180 degrees apart through the d-axis. The flux barrier 30c includes a substantially linear void layer 32, a first bridge portion 34a formed of an iron core located between one longitudinal end of the void layer 32 and the outer circumferential surface, and a first bridge portion 34a formed of an iron core located between one longitudinal end of the void layer 32 and the outer peripheral surface. It has a second bridge portion 34b formed of an iron core located between the other end and the outer peripheral surface.
The three-layer flux barriers 30a, 30b, and 30c are formed between a plurality of magnetic paths through which the magnetic flux formed by the stator 12 passes, and partition each magnetic path. The first bridge portion 34a and the second bridge portion 34b of the flux barrier of each phase have a radial width WO. The first bridge portion 34a and the second bridge portion 34b play a role of coupling (connecting) the rotor cores 24 separated by the gap layer 32 of each flux barrier 30a, 30b, 30c. Note that the radial width WO of the first bridge portion 34a and the second bridge portion 34b belonging to each layer is not limited to a constant value, and may be non-uniform.

The void layer 32 of each flux barrier 30a, 30b, 30c is filled with a non-magnetic insulator (air, resin, etc.) to form a barrier region 40 having a lower magnetic permeability than the core portion. The barrier region 40 has a property that allows magnetic flux to pass through it more easily than the magnetic path. According to this embodiment, in the three-layer flux barriers 30a, 30b, and 30c, at least a portion of each barrier region 40, for example, the central portion in the longitudinal direction, is replaced with a hard magnetic region 42 filled with a hard magnetic material. It is being The hard magnetic material is a material that constitutes a permanent magnet, and includes, for example, a rare earth magnet, a ferrite magnet, an alnico magnet, a samarium iron cobalt magnet, and the like. The hard magnetic region 42 may be magnetized, unmagnetized, or incompletely magnetized. The hard magnetic region 42 is arranged to cross the d-axis and has a predetermined length in the longitudinal direction. In this embodiment, the hard magnetic regions 42 are provided symmetrically with respect to the d-axis. In the flux barriers 30a, 30b, and 30c, the regions excluding the hard magnetic region 42 are the barrier region 40 and the bridge portions 34a, 34b.
The easy axis direction of magnetization of each hard magnetic region 42 is approximately parallel to the d-axis direction. Note that the recoil relative magnetic permeability of the general hard magnetic material described above is approximately 1.

Even in the two-magnetic-pole reluctance motor 10 configured as described above, the same effects as those of the reluctance motor according to the first embodiment described above can be obtained.
In the third embodiment, the void layer 32 of each flux barrier is not limited to a continuous single layer, but may be divided into a plurality of void layers. That is, as in the second and third modifications described above, a bridge may be provided at one or more locations in the longitudinal direction of the void layer 32.
Alternatively, part or all of the barrier region 40 may be charged with a non-magnetic conductor, and the barrier region may be replaced with a conductive region. Copper, aluminum, stainless steel, etc. can be used as the nonmagnetic conductor.

Although some embodiments and modifications of the present invention have been described, these embodiments and modifications are presented as examples and are not intended to limit the scope of the invention. The novel embodiments and modifications can be implemented in various other forms, and various omissions, substitutions, and changes can be made without departing from the gist of the invention. The embodiments and their modifications are included within the scope and gist of the invention, as well as within the scope of the invention described in the claims and its equivalents.

All configurations that can be implemented by appropriately changing the design based on the configurations described above as embodiments of the present invention by those skilled in the art also belong to the scope of the present invention as long as they include the gist of the present invention. For example, in the embodiment, a rotor with four magnetic poles or two magnetic poles is shown, but the rotor is not limited to this, and the rotor may have six or more magnetic poles. The dimensions and shape of the rotor, the number of layers of the flux barrier, the shape of the bridge portion, etc. are not limited to the embodiments described above, and can be changed in various ways according to the design.

10... Rotating electric machine, 12... Stator, 14... Rotor, 16... Stator core,
18... Armature winding, 20... Slot, 22... Shaft, 24... Rotor core,
30a, 30b, 30c, 30d...Flux barrier, 32...Void layer,
32a...first bridge part, 32b...second bridge part, 40...barrier region,
42...Hard magnetic region, 50...Electroconductive region

Claims (3)

A shaft that can freely rotate around the central axis,
a rotor core having a plurality of magnetic poles arranged in a circumferential direction around the central axis and fixed to the shaft;
The magnetic poles of the rotor core are formed with a plurality of layers of flux barriers extending from one location to another on the outer circumferential surface of the rotor core, arranged so as to pass through predetermined axes passing through the central axis. ,
The flux barrier includes a first bridge portion and a second bridge portion that form a part of the outer peripheral surface of the rotor core at both longitudinal ends of the flux barrier, and a first bridge portion and a second bridge portion. a void layer located between;
At least one layer of flux barrier has a magnetization reversible hard magnetic region formed of a hard magnetic material filled in at least a portion of the gap layer,
Imax: Maximum effective value of three-phase current flowing when starting at rated voltage, Hc: Coercive force of hard magnetic material, Nt: Number of series conductors in slots Ns: Number of slots, p: Number of magnetic poles, Nc: Parallel When the number of circuits and tm is the total thickness of the hard magnetic region per magnetic pole,

A rotor that satisfies the relational expression . The rotor according to claim 1, wherein in the gap layer of the flux barrier, a region other than the hard magnetic region forms a barrier region having a lower magnetic permeability than the core portion. In the gap layer of at least one layer of the flux barrier, a region other than the hard magnetic region is filled with a non-magnetic conductor, and is a conductive region having lower magnetic permeability and higher electrical conductivity than the core portion. 2. The rotor according to claim 1, wherein the rotor is formed with:

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