JP2005006416A - Self-starting reluctance motor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a self-stating reluctance motor which has a high power factor and efficiency without using a permanent magnet. <P>SOLUTION: In the self-starting reluctance motor of a two-pole constitution which is equipped with a rotor where a rotor core 1 is fixed to a rotor shaft 3, flux barrier slits 2a, 2b, 2c and 2d of four or more layers per pole are formed in the radial direction of the rotor core, and the flux barrier slits are injected with a nonmagnetic conductive material 4 so as to form secondary conductors, and the flank 2a1 on the rotor shaft side of the flux barrier slit in the outermost layer is convex in the peripheral direction of the rotor core in its cross section vertical to the axial direction of the rotor. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a reluctance motor that is a synchronous motor using reluctance torque, and more particularly to a self-starting reluctance motor having a two-pole configuration.
[0002]
[Prior art]
A conventional self-starting synchronous motor driven by a commercial power supply and having a single-phase two-pole configuration includes a stator having a stator winding and a rotor that rotates within the stator. Is configured to include a cage-type secondary conductor provided in the periphery of the rotor core and a permanent magnet embedded in the rotor core, and can self-start in the same manner as a conventional induction motor. Further, during operation, synchronous operation can be ensured by the action of the embedded permanent magnet (see, for example, Patent Document 1).
[0003]
[Patent Document 1]
JP 2001-275286 A (page 4-5, FIGS. 3 and 8)
[0004]
[Problems to be solved by the invention]
The conventional two-pole self-starting synchronous motor has a problem that the production cost is much higher than that of the induction motor because a permanent magnet is used.
In addition, since the slit containing the permanent magnet acts as a flux barrier that restricts the flow of magnetic flux and has magnetic saliency, the conventional synchronous motor is similar to the induction motor in spite of the occurrence of reluctance torque. Since the cage-type secondary conductor is provided around the rotor core, there is a problem that the reluctance torque cannot be used effectively and the power factor and efficiency are poor.
[0005]
The present invention has been made to solve the above-described problems of the conventional ones, and an object thereof is to provide a self-starting reluctance motor having a high power factor and high efficiency without using a permanent magnet. .
[0006]
[Means for Solving the Problems]
A self-starting reluctance motor according to the present invention is a self-starting reluctance motor having a two-pole configuration provided with a rotor formed by fixing a rotor core to a rotor shaft, and has four or more flux barriers per pole in the radial direction of the rotor core. A slit is provided, a non-magnetic conductive material is injected into the flux barrier slit to form a secondary conductor, and the side surface on the rotor shaft side of the flux barrier slit in the innermost layer is the axis of the rotor It has a convex shape in the outer circumferential direction of the rotor core in a cross section perpendicular to the direction.
[0007]
DETAILED DESCRIPTION OF THE INVENTION
Embodiment 1 FIG.
FIG. 1 shows a configuration of a rotor (rotor) which is a main part of a two-pole self-starting reluctance motor according to Embodiment 1 of the present invention, and a plane perpendicular to the direction of the rotor axis (rotation center axis). FIG. In the figure, a rotor (rotor) is formed by fixing a rotor core 1 in which a plurality of core sheets made of thin electromagnetic steel plates are laminated in an axial direction to a shaft (rotor shaft) 3. Flux barrier slits 2 a, 2 b, 2 c, 2 d (hereinafter sometimes represented by 2) for forming a magnetoresistive difference in the rotor rotation direction are 4 per pole in the radial direction of the rotor core 1 (core sheet). Layers are provided. Between each flux barrier slit 2a, 2b, 2c, 2d or between the flux barrier slit 2a and the shaft 3, a magnetic path having a small magnetic resistance and a path for magnetic flux is formed.
[0008]
Further, the side surface 2al on the rotor shaft (shaft) 3 side of the flux barrier slit 2a in the innermost layer has a convex shape in the outer circumferential direction of the rotor core 1 in a cross section perpendicular to the axial direction of the rotor, As for the width between the side surfaces 2al on the shaft 3 side of the two flux barrier slits 2a facing each other across the shaft 3, the width Wo at the end is narrower than the width Wq on the q axis. By adopting such a shape, it is possible to make the end width Wo of the magnetic path along the d-axis sandwiching the shaft 3 as shown by the broken-line arrow in FIG. As a result, it becomes possible to reduce the leakage of the magnetic flux in the section, thereby improving the power factor and efficiency. In FIG. 1, the side surface 2al has a smooth arc shape (curved shape), but may be configured by a plurality of straight lines.
[0009]
A conductive nonmagnetic material is injected as an injection member 4 into the flux barrier slit 2 to form a secondary conductor. The conductive nonmagnetic material in each slit 2 is coupled and fixed by a short-ring-shaped nonmagnetic material coupling member provided on both axial end surfaces of the rotor. The injection member 4 to the flux barrier slit 2 and the coupling member provided on the rotor end face are integrally formed by a die-casting method using a non-magnetic and conductive material such as copper or copper alloy, aluminum or aluminum alloy, for example. By forming the secondary conductor, self-starting by a commercial power supply becomes possible.
[0010]
As the stator (stator), for example, a 24-slot stator as shown in FIGS. 2 and 3 is used. 2 and 3 are cross-sectional views showing an example and another example of the stator of the self-starting reluctance motor according to Embodiment 1 of the present invention, respectively. In FIG. 2, the stator core (stator core) 10 has 24 stator slots 11 formed in the circumferential direction, and each slot 11 includes a main winding 6a and an auxiliary winding 6b. A single-layer two-pole winding is wound. 9 is a tooth.
In FIG. 3, eight stator slots 11 are formed in the circumferential direction between adjacent teeth 9, and four main windings 6 a wound in a ring shape in the slots 11. The four auxiliary windings 6b are alternately accommodated to form a so-called concentrated winding stator having a single layer and two poles.
The stator of the self-starting reluctance motor according to the present embodiment is not limited to that shown in FIGS. 2 and 3, and the number of slots 11 may be 26 or 28, for example.
[0011]
The motor according to the present invention generates a reluctance torque because the rotor has magnetic saliency, and operates synchronously with the reluctance torque. Having magnetic saliency means the inductance L _d in the d-axis direction, which is the direction in which the magnetic flux is most likely to pass, as shown in FIG. 1, and the inductance L _q in the q-axis direction, which is a direction electrically rotated 90 degrees with respect to the d-axis. There is a difference in At this time, the reluctance torque is expressed by equation (1).
_{T = P n (L d -L} q) I d I q (1)
P _n : Number of pole pairs L _d : d-axis inductance L _q : q-axis inductance I _d : d-axis current I _q : q-axis current Further, the power factor pf can be roughly calculated by the equation (2).
pf = (L _d / L _q −1) / (L _d / L _q +1) (2)
L _d / L _q : salient pole ratio Here, the above formulas (1) and (2) show the formula of torque after conversion to the dq axis, and the d axis inductance L _d and the q axis inductance L _q The magnitude of torque is determined by the difference (Ld−Lq). The power factor is determined by the salient pole ratio L _d / L _q (ratio between the d-axis inductance L _d and the q-axis inductance L _q ).
[0012]
FIG. 4 is an explanatory diagram showing the flow of magnetic flux. As shown in FIG. 4, the flow of the magnetic flux in the q-axis direction indicated by the arrow 22 passes through the portion of the flux barrier whose permeability is substantially the same as that of air four times, so that the magnetic resistance increases and the q-axis inductance L _q becomes smaller. On the other hand, the d-axis direction is a runny direction of the magnetic flux, the magnetic flux flows in the d-axis direction indicated by the arrow 21, so passes a small portion of the magneto-resistance, the d-axis inductance L _d increases. As a result, a difference occurs between the d-axis inductance L _d and the q-axis inductance L _q, and the reluctance torque shown in the equation (1) is generated by flowing the d-axis current I _d and the q-axis current I _q .
[0013]
FIG. 5 is a simulation result by a computer (represented by white triangles Δ in FIG. 5) in which the relationship between the number of flux barrier slit (flux barrier) layers and the d-axis inductance L _d and the q-axis inductance L _q is examined. . FIG. 5 also shows the result of calculating the salient pole ratio in a conventional motor (indicated by black triangles in FIG. 5). As a conventional motor, a motor having the configuration shown in FIG. 8 of Japanese Patent Laid-Open No. 2001-275286 cited as a conventional technique was used. The calculation condition is that the stator with 24 slots shown in FIG. 2 is used, and the rotor is not cage-shaped as a secondary conductor, and the nonmagnetic conductive material 4 is injected into the flux barrier slit 2 as shown in FIG. The rotor shape is used. From FIG. 5, it can be seen that the difference between the d-axis inductance L _d and the q-axis inductance L _q is large and almost constant in the flux barrier of four layers or more.
Further, as shown in FIG. 5, the difference (L _d −L _q ) between the d-axis inductance L _d and the q-axis inductance L _q is 20% in the motor according to the present embodiment, compared with the conventional motor. A high value is shown. This is because, in a conventional synchronous motor, a cage-type secondary conductor is provided in the periphery of the rotor core in the same manner as an induction motor, and therefore magnetic flux leakage occurs between the cage-type secondary conductor and the flux barrier. However, the reluctance motor according to the present embodiment cannot effectively use the reluctance torque, but the secondary conductor is formed by injecting the nonmagnetic conductive material 4 into the flux barrier slit 2. This is thought to be due to the absence of leakage.
[0014]
FIG. 6 is a simulation result (indicated by white squares □ in FIG. 6) by a computer that examines the relationship between the number of flux barrier layers and the salient pole ratio L _d / L _q . FIG. 6 also shows the result of calculating the salient pole ratio in a conventional motor (indicated by black squares in FIG. 6). The calculation conditions are the same as in the case of FIG. FIG. 6 shows that when the number of flux barrier layers is three or more, the salient pole ratio is large and almost constant.
Further, as shown in FIG. 6, the salient pole ratio L _d / L _q is about twice as high as that of the conventional motor in the case of the motor according to the present embodiment. As in the case of the difference (L _d −L _q ) between the d-axis inductance L _d and the q-axis inductance L _q shown in FIG. 5, in the conventional synchronous motor, the rotor core is similar to the induction motor. Since the cage-type secondary conductor is provided in the peripheral portion, magnetic flux leaks between the cage-type secondary conductor and the flux barrier, and the reluctance torque cannot be effectively used. In the reluctance motor, since the secondary conductor is formed by injecting the nonmagnetic conductive material 4 into the flux barrier slit 2, it is considered that magnetic flux leakage does not occur.
[0015]
As described above, the self-starting reluctance motor having a two-pole configuration according to the present embodiment has a nonmagnetic conductive property in the flux barrier slit 2 without using a squirrel-cage secondary conductor in order to provide a self-starting property. The material 4 is injected to form a secondary conductor, and the side 2a1 on the rotor shaft side of the flux barrier slit 2a in the innermost layer has an outer periphery of the rotor core 1 in a cross section perpendicular to the axial direction of the rotor. Since it has a convex shape in the direction, it is possible to obtain a self-starting reluctance motor with reduced inductance and high salient pole ratio, high power factor and efficiency by reducing magnetic flux leakage at the end.
Further, in a motor that uses a reluctance torque by providing a flux barrier in the rotor core 1 to increase the difference between the d-axis inductance L _d and the q-axis inductance L _q , the flux barrier has three or more layers, preferably four or more layers. Since the reluctance torque can be utilized to the maximum extent, the structure has a high efficiency and a high power factor, and the performance of the motor can be improved.
[0016]
FIG. 7 shows the width of the flux barrier slit (hereinafter referred to as the flux barrier slit width) on the q-axis (the direction that is electrically rotated 90 degrees with respect to the d-axis, which is the direction through which the magnetic flux easily passes). .) And the width of the magnetic path (hereinafter sometimes referred to as the magnetic path width). In the figure, Wf1 to Wf4 are magnetic path widths on the q axis, and Wb1 to Wb4 are on the q axis. It is a flux barrier slit width (flux barrier width). Wc is the bridge width.
FIG. 8 shows the inductance difference (indicated by white triangles Δ in FIG. 8) and salient pole ratio (in FIG. 8, calculated with the ratio of the total flux barrier slit width to the core width on the q axis as a parameter). FIG. 5 is a characteristic diagram showing a black square. Here, the core width on the q-axis is a width calculated by Wf1 + Wf2 + Wf3 + Wf4 + Wb1 + Wb2 + Wb3 + Wb4 + Wc, and the total flux barrier width on the q-axis is a width calculated by Wb1 + Wb2 + Wb3 + Wb4.
[0017]
From FIG. 8, the inductance difference is large and almost constant when the ratio of the total flux barrier slit width to the core width (total flux barrier width / core width value) is about 0.4 to 0.6. It can be seen that the ratio is large and substantially constant when the total flux barrier width / core width is in the range of about 0.2 to 0.6. Therefore, by setting the value of the total flux barrier width / core width on the q axis within a range of about 0.4 to 0.6, preferably within a range of 0.45 to 0.55, an inductance difference, Both salient pole ratios can be configured to be large.
[0018]
In the present embodiment, the width Wo between the side surfaces 2al on the shaft 3 side of the two flux barrier slits 2a facing each other across the shaft 3 is smaller than the width Wq on the q axis. As described above, the end width Wo of the magnetic path including the shaft 3 can be made narrower than the diameter of the shaft 3 and the leakage of magnetic flux at the end can be reduced. By making the width Wo at the end narrower than the status lot pitch, leakage at the end can be further reduced.
[0019]
In the above embodiment, a single-phase two-pole self-starting reluctance motor has been described. However, the present invention is not limited to a single phase, and may be two-phase or three-phase. However, the self-starting reluctance motor having a single-phase two-pole configuration can be driven by a single-phase commercial power source for home use, and does not require a special three-phase power source facility. Can be used.
[0020]
Embodiment 2. FIG.
FIG. 9 is a cross-sectional view taken along a plane perpendicular to the axial direction of the rotor, showing the configuration of the rotor that is the main part of the self-starting reluctance motor having a two-pole configuration according to Embodiment 2 of the present invention.
In the first embodiment, the magnetic path widths Wf1, Wf2, Wf3, and Wf4 on the q axis are all the same value, and the flux barrier widths Wb1, Wb2, Wb3, and Wb4 on the q axis are all the same. It is the same value. On the other hand, in the present embodiment, the magnetic path widths Wf1, Wf2, Wf3, and Wf4 on the q axis have different values, and the flux barrier widths Wb1, Wb2, and Wb3 on the q axis are different from each other. The value is different from Wb4. Since the other configuration is the same as that of the first embodiment, differences from the first embodiment will be mainly described below.
[0021]
According to this configuration, the magnetic path widths Wf1, Wf2, Wf3, and Wf4 and the flux barrier widths Wb1, Wb2, Wb3, and Wb4 can be set freely, so that depending on the saturation of each magnetic path Each magnetic path width and each flux barrier width can be set, and the d-axis inductance Ld and the q-axis inductance Lq can be set arbitrarily to some extent, and the power factor and efficiency can be further improved.
[0022]
In FIG. 9, each magnetic path width Wf1, Wf2, Wf3, Wf4 has a different value, and each flux barrier width Wb1, Wb2, Wb3, Wb4 has a different value, but some of them have the same value. Alternatively, at least one of the flux barrier slit widths may have a different value, or at least one of the magnetic path widths may have a different value.
[0023]
Embodiment 3 FIG.
FIG. 10 shows a configuration of a rotor that is a main part of a self-starting reluctance motor having a two-pole configuration according to Embodiment 3 of the present invention, and is a cross-sectional view taken along a plane perpendicular to the axial direction of the rotor. In the present embodiment, ribs 5a, 5b, 5c, and 5d (hereinafter may be represented by 5) are provided at the center of each flux barrier slit 2a, 2b, 2c, and 2d. Since the other configuration is the same as that of the first embodiment, differences from the first embodiment will be mainly described below.
In addition, the rib 5 said by this invention is a member erected in the short side direction of the flux barrier slit 2, and divides the flux barrier slit 2, for example, consists of the same material as the rotor core 1 (core sheet).
[0024]
As the rotor rotates, centrifugal force is generated in each of the flux barrier slits 2a, 2b, 2c, and 2d, which may swell toward the outer peripheral side, and the rotor outer diameter may increase. When the outer diameter of the rotor increases, there arises a disadvantage that the rotor cannot be rotated smoothly due to contact with the stator. On the other hand, in the present embodiment, since the rib 5 is provided, the strength against centrifugal force is increased, and expansion of the flux barrier slits 2a, 2b, 2c, 2d to the outer peripheral side can be suppressed. . As a result, expansion of the rotor outer diameter can be suppressed.
[0025]
In FIG. 9, one rib 5 is provided on the q axis, but the installation position may be moved from the q axis, and the number of ribs 5 may be two or more. Further, the ribs 5a, 5b, 5c and 5d do not have to be on the same straight line, and when they are shifted from the straight line, the magnetoresistance in the q-axis direction is increased. Further, the widths of the ribs 5a, 5b, 5c, and 5d may not be the same (for example, the width of the flux barrier slit 2d at the outermost periphery having a large angular velocity is increased). Further, the rib 5 does not necessarily have to be provided in all the flux barrier slits 2a, 2b, 2c, and 2d. At least one flux barrier slit (for example, a flux barrier slit 2d at the outermost periphery having a large angular velocity). May be provided in at least one place.
[0026]
Embodiment 4 FIG.
FIG. 11 is a cross-sectional view of a rotor that is a main part of a self-starting reluctance motor having a two-pole configuration according to Embodiment 4 of the present invention, taken along a plane perpendicular to the axial direction of the rotor. In the present embodiment, the shape of the rotor shaft (shaft) 3 in the cross section perpendicular to the axial direction (axial direction of the rotor and axial direction of the rotor shaft 3) is the length of the flux barrier slit 2 arrangement direction (q-axis direction). Is non-circular shorter than the length in the other direction. Since the other configuration is the same as that of the first embodiment, differences from the first embodiment will be mainly described below.
[0027]
In the present embodiment, both ends of the shaft 3 in the q-axis direction are dropped, and the shape of the shaft 3 in the cross section perpendicular to the axial direction is a non-circular shape whose length in the q-axis direction is shorter than the length in the other direction. .
According to the present embodiment, the width of the magnetic path along the d-axis (d-axis magnetic path) sandwiching the shaft 3 is the narrowest in the vicinity of the shaft 3, so that the shape of the shaft 3 is the q-axis. By making the length in the direction non-circular shorter than the length in the other direction, the width of the d-axis magnetic path can be increased, and the inductance difference and salient pole ratio can be increased. That is, when the d-axis magnetic path width is increased, the d-axis magnetic resistance is reduced, so that the d-axis inductance Ld is increased. On the other hand, since the width of the flux barrier 2 is universal, the q-axis inductance Lq is not changed. As a result, the inductance difference (Ld−Lq) and the salient pole ratio Ld / Lq can be increased.
[0028]
In addition, in FIG. 11, although it has the shape which dropped the both ends of the shaft 3, it is not restricted to this, The shape of the shaft 3 in the cross section perpendicular | vertical to an axial direction is the length of the q direction in the other direction. Any other shape such as an elliptical shape may be used as long as it is shorter than the length.
[0029]
【The invention's effect】
As described above, according to the present invention, in a two-pole self-starting reluctance motor having a rotor formed by fixing a rotor core to a rotor shaft, a flux barrier having four or more layers per pole in the radial direction of the rotor core. A slit is provided, a non-magnetic conductive material is injected into the flux barrier slit to form a secondary conductor, and the side surface on the rotor shaft side of the flux barrier slit in the innermost layer is the axis of the rotor Since the rotor core has a convex shape in the outer circumferential direction in the cross section perpendicular to the direction, the leakage of magnetic flux at the end is reduced without using a permanent magnet, and the inductance difference and salient pole ratio are reduced. A high power factor and high efficiency self-starting reluctance motor is obtained.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing a configuration of a rotor that is a main part of a two-pole self-starting reluctance motor according to a first embodiment of the present invention.
FIG. 2 is a cross-sectional view showing an example of the configuration of a stator of a self-starting reluctance motor having a two-pole configuration according to Embodiment 1 of the present invention.
FIG. 3 is a cross-sectional view showing another example of a configuration of a concentrated winding stator of a self-starting reluctance motor having a two-pole configuration according to Embodiment 1 of the present invention;
FIG. 4 is an explanatory diagram showing the flow of magnetic flux according to the first embodiment of the present invention.
FIG. 5 is a characteristic diagram related to the first embodiment of the present invention and showing the relationship between the number of flux barrier layers and the d-axis inductance L _d and the q-axis inductance L _q .
FIG. 6 is a characteristic diagram related to the first embodiment of the present invention and showing the relationship between the number of flux barrier layers and the salient pole ratio L _d / L _q .
FIG. 7 is a diagram for explaining the width of a flux barrier slit and the width of a magnetic path on the q axis according to the first embodiment of the present invention.
FIG. 8 is a characteristic diagram related to the first embodiment of the present invention and showing the relationship between the total flux barrier slit width / core width value, the inductance difference, and the salient pole ratio on the q axis.
FIG. 9 is a sectional view showing a configuration of a rotor that is a main part of a two-pole self-starting reluctance motor according to a second embodiment of the present invention.
FIG. 10 is a cross-sectional view showing a configuration of a rotor that is a main part of a two-pole self-starting reluctance motor according to a third embodiment of the present invention.
FIG. 11 is a cross-sectional view showing a configuration of a rotor that is a main part of a two-pole self-starting reluctance motor according to a fourth embodiment of the present invention.
[Explanation of symbols]
1 Rotor core, 2, 2a, 2b, 2c, 2d Flux barrier slit, 3 shaft, 4 injection member (nonmagnetic conductive material), 5, 5a, 5b, 5c, 5d rib, 6a main winding, 6b auxiliary winding , 9 teeth, 10 stator core, 11 slots.

Claims (5)

In a self-starting reluctance motor having a two-pole configuration having a rotor formed by fixing a rotor core to a rotor shaft, four or more layers of flux barrier slits per pole are provided in the radial direction of the rotor core, A non-magnetic conductive material is injected to form a secondary conductor, and the side surface on the rotor shaft side of the flux barrier slit in the innermost layer is a cross-section perpendicular to the axial direction of the rotor. A self-starting reluctance motor characterized by having a convex shape in the outer circumferential direction. The ratio of the total flux barrier slit width, which is the sum of the widths of the respective flux barrier slits to the core width on the q axis, is in the range of 0.4 to 0.6. Start-up reluctance motor. 3. The width of each flux barrier slit on the q-axis is a different value, or at least one of the widths of each magnetic path on the q-axis is a different value. Self-starting reluctance motor. 2. The self-starting reluctance motor according to claim 1, wherein a rib is provided in at least one portion of the flux barrier slit. 2. The self-starting reluctance motor according to claim 1, wherein the shape of the rotor shaft in a cross section perpendicular to the axial direction is a non-circular shape whose length in the flux barrier slit arrangement direction is shorter than the length in the other direction.

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