JP6393843B1 - Switched reluctance motor - Google Patents

Abstract

A switch capable of preventing leakage magnetic flux while shortening the magnetic path length and obtaining higher efficiency than the conventional one by using a magnetic circuit that concentrates magnetic flux in a place where the magnetic field strength around the excitation pole in the rotor is high. A trilactance motor is provided. A switched reluctance motor (1) includes a rotor (4) having rotor salient poles (4a, 4b, 4c) arranged at equal intervals in the circumferential direction around an output shaft (3), and a stator salient pole (5a) around the output shaft (3). , 5b, 5c, and 5d are arranged at equal intervals in the circumferential direction, and windings 6a, 6b, 6c, and 6d that are concentratedly wound around the stator salient poles. Adjacent salient poles in the salient poles 5a, 5b, 5c and 5d have a configuration in which the winding directions of the windings 6a, 6b, 6c and 6d are opposite to each other. [Selection] Figure 2

Description

  The present invention relates to a switched reluctance motor and a driving method thereof.

  A switched reluctance motor (abbreviated as SRM) consists of a stator (stator) around which windings are wound and a rotor (rotor) made of a ferromagnetic iron core without using a permanent magnet. And is rotated by a reluctance torque generated by energizing the winding with a non-sinusoidal current from a DC power source. Examples of the non-sinusoidal current include a pulsed current such as a rectangular wave.

  A conventional switched reluctance motor is known as a three-phase 6/4 type with a single-phase excitation method in which the number of phases of distributed winding is 3, the number of slots in the stator is 6, and the number of salient poles in the rotor is 4. ing. Further, there is known a three-phase 12/8 type of one-phase excitation method in which the number of phases of the distributed winding is 3, the number of slots of the stator is 12, the number of salient poles of the rotor is 8, and the one-phase excitation system is used (Patent Document 1). : Japanese Patent Laid-Open No. 2002-354881, Japanese Patent Laid-Open No. 2003-061381). Here, the number of slots of the stator matches the number of salient poles of the stator.

JP 2002-354881 A JP 2003-061381 A

  The conventional switched reluctance motors described in Patent Document 1 and Patent Document 2 use a magnetic circuit that traverses the rotor by passing an exciting current through distributed windings, which increases the magnetic path length. There is a problem that efficiency is low because a low magnetic flux region such as leakage magnetic flux is generated.

  The present invention has been made in view of the above circumstances, and is not a magnetic circuit that traverses the rotor, but a magnetic circuit that concentrates the magnetic flux in a place where the magnetic field intensity around the excitation pole in the rotor is high, while shortening the magnetic path length. An object of the present invention is to provide a switched reluctance motor capable of preventing leakage magnetic flux and obtaining higher efficiency than the conventional one and a driving method thereof.

  As an embodiment, the above-described problem is solved by a solution as disclosed below.

The switched reluctance motor of the present invention has a rotor in which rotor salient poles are arranged at equal intervals in the circumferential direction around the output shaft, and stator salient poles are arranged at equal intervals in the circumferential direction around the output shaft. The stator salient poles and windings concentratedly wound around the stator salient poles, the number of the rotor salient poles being n (n is a natural number of 2 or more), the number of stator salient poles being 4n, and a phase number 4 of the winding, adjacent salient poles of each of said stator salient poles, the winding direction of the winding has become opposite to each other, said stator collision the winding is energized The first salient pole that is excited among the stator salient poles, and the second salient pole that is disposed adjacent to the first salient pole and the rotor in a predetermined rotational direction, with the poles excited in two phases. Opposite to both the first salient pole and the second salient pole of the rotor salient pole A magnetic circuit is formed by the third salient pole at a position where the length of the portion of the third salient pole facing the second salient pole is opposite to the first salient pole of the third salient pole. The second salient pole and the third salient pole are in contact with each other in a state larger than the length of the portion .

  According to the present invention, an excitation pole in a rotor is not provided by flowing an excitation current through concentrated windings, rather than a magnetic circuit traversing the rotor by passing an excitation current through distributed windings as in the prior art. Since the magnetic circuit concentrates the magnetic flux in a place with a high magnetic field strength around the magnetic field, it is possible to prevent the leakage magnetic flux while shortening the magnetic path length and obtain higher efficiency than the conventional one. The adjacent salient poles in each of the stator salient poles have the winding directions of the windings opposite to each other. In comparison, a magnetic flux having a large magnetic flux density can be looped, and when a magnetic material enters the magnetic field, a large torque works. Therefore, the number of coil turns can be compressed to make the size compact.

  As an example, the number of the rotor salient poles can be 2, 3, 4, 5, 6. When the number of rotor salient poles is 2, the number of stator salient poles is 8. When the number of the rotor salient poles is 3, the number of the stator salient poles is 12. When the number of rotor salient poles is 4, the number of stator salient poles is 16. When the number of rotor salient poles is 5, the number of stator salient poles is 20. When the number of rotor salient poles is 6, the number of stator salient poles is 24. If the ratio of the number of rotor salient poles to the number of stator salient poles is 1: 4, the number of rotor salient poles can be increased in addition to the above.

  The method of driving the switched reluctance motor according to the present invention is such that the number of rotor salient poles is n (n is a natural number of 2 or more), the number of stator salient poles is 4n, and the number of winding phases is 4, Adjacent salient poles in the stator salient poles generate a pulsed non-sinusoidal current from the DC power source to the windings when driving a switched reluctance motor in which the winding directions of the windings are concentrated in opposite directions. The stator salient poles are energized sequentially to excite the stator salient poles, and the first salient poles of the stator salient poles are excited, and the first salient poles and the rotor are disposed adjacent to the rotor in a predetermined rotational direction. A magnetic circuit is formed by the second salient pole and the third salient pole at a position facing both the first salient pole and the second salient pole of the rotor salient pole.

  According to the present invention, in the switched reluctance motor which is a four-phase motor, the pole utilization factor is theoretically increased to 50% by the method of exciting two phases simultaneously. Therefore, when the number of rotor poles is the same, Twice the electric power of the motor can be input to obtain a higher torque than before.

  According to the present invention, instead of a magnetic circuit crossing the rotor, a magnetic circuit that concentrates the magnetic flux in a place where the magnetic field strength around the excitation pole in the rotor is high, thereby preventing leakage magnetic flux while shortening the magnetic path length, It becomes the structure which can obtain efficiency higher than before. Moreover, since the pole utilization factor is increased to 50%, when the number of rotor poles is the same, it is possible to obtain twice the electric power of the motor of the prior art and obtain a higher torque than before. And the radial type switched reluctance motor is realizable by the structure by which the clearance gap between a rotor and a stator is a radial gap. Further, an axial type switched reluctance motor can be realized by a configuration in which the gap between the rotor and the stator is an axial gap.

FIG. 1 is a schematic perspective view of an example of a switched reluctance motor according to a first embodiment of the present invention viewed obliquely from above. 2 is a sectional view taken along line II-II in FIG. FIG. 3 is a schematic cross-sectional view showing the rotor according to the first embodiment. 4A is a schematic cross-sectional view showing another example of the rotor according to the first embodiment, and FIG. 4B is a schematic cross-sectional view showing another example of the rotor according to the first embodiment. FIG. 5A is a graph showing drive signal waveforms according to the first embodiment, and FIG. 5B is a schematic circuit diagram showing the drive circuit according to the first embodiment. FIG. 6 is a schematic perspective view of an example of a switched reluctance motor according to the second embodiment of the present invention viewed obliquely from above. FIG. 7 is a longitudinal sectional view schematically showing a switched reluctance motor according to the second embodiment. FIG. 8A is a schematic plan view showing the rotor according to the second embodiment, and FIG. 8B is a schematic bottom view showing the rotor according to the second embodiment. FIG. 9A is a schematic bottom view showing the stator according to the second embodiment, and FIG. 9B is a schematic plan view showing the stator according to the second embodiment. FIG. 10 is a graph showing drive signal waveforms according to the second embodiment.

(First embodiment)
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a schematic perspective view showing an example of a radial switched reluctance motor 1 according to the first embodiment. In the switched reluctance motor 1 of the first embodiment, a rotor 4 is disposed around a P1-P1 line passing through the center of an output shaft 3 (shaft) in the Z direction, and the outer side of the rotor 4 is centered on the output shaft 3. A stator 5 is disposed on the surface.

  Here, in order to make it easy to explain the positional relationship of each part of the switched reluctance motor 1, directions are indicated by arrows X, Y, and Z in the drawing. When the switched reluctance motor 1 is actually used, it is not limited to these directions, and any direction can be used. Note that components having the same function are denoted by the same reference symbols throughout the drawings for describing the embodiments, and the repetitive description thereof may be omitted.

  As an example, the rotor 4 and the stator 5 are made of non-oriented electrical steel sheets. As an example, the output shaft 3 is made of steel.

  FIG. 2 is a longitudinal sectional view of the switched reluctance motor 1. In the example shown in FIG. 2, the rotor 4 has rotor salient poles 4 a, 4 b, 4 c arranged at equal intervals in the circumferential direction around the P <b> 1-P <b> 1 line of the output shaft 3. Stator salient poles 5a, 5b, 5c, and 5d are arranged at equal intervals in the circumferential direction so as to surround the rotor 4 around the P1-P1 line of the shaft 3. The rotor salient pole 4a, the rotor salient pole 4b, and the rotor salient pole 4c are disposed at positions that are rotationally symmetric about the P1-P1 line. Further, the stator salient pole 5a, the stator salient pole 5b, the stator salient pole 5c, and the stator salient pole 5d are disposed at positions that are rotationally symmetric about the line P1-P1. And the winding 6a, 6b, 6c, 6d concentratedly wound so that each of the stator salient poles 5a, 5b, 5c, 5d may be provided.

  In the example shown in FIG. 2, the number of poles of the rotor 4 is 3, the number of poles of the stator 5 is 12, and the number of winding phases is 4. Here, the number of slots of the stator 5 matches the number of salient poles of the stator 5.

  Adjacent salient poles in the stator salient poles 5a, 5b, 5c, 5d have the winding directions of the windings 6a, 6b, 6c, 6d opposite to each other. For example, the stator salient pole 5a and the stator salient pole 5b have the winding directions of the winding 6a and the winding 6b reversed, and the stator salient pole 5a and the stator salient pole 5d are the same as the winding 6a. The winding direction with the winding 6d is opposite. The windings 6a, 6b, 6c and 6d are connected in series with the same phase.

  As a result, in the stator 5, adjacent electromagnets having opposite polarities are configured, so that a magnetic flux having a large magnetic flux density can be looped compared to the distributed winding as in the prior art, and the magnetic field is made of a magnetic material. When each pole of a certain rotor 4 enters, a large torque acts on the rotor 4. In addition, since two-phase excitation is performed, a simple controller for adjusting the excitation timing may be used. As a configuration other than the above, the same phase can be connected in parallel.

  FIG. 5A is a graph showing drive signal waveforms according to the first embodiment. The vertical axis represents voltage V, and the horizontal axis represents time T. FIG. 5B is a schematic circuit diagram showing the drive circuit 9 according to the first embodiment, which is a half-bridge circuit. In the present embodiment, the output shaft 3 is rotated by reluctance torque generated by applying a pulsed non-sinusoidal current from the DC power source E to the windings 6a, 6b, 6c, 6d. As this non-sinusoidal current, a rectangular wave pulse current is continuously energized.

  As shown in FIG. 5A, after the rotor 4 is started, the drive voltages Va, Vb, Vc, and Vd are applied by shifting the timing one phase at a time so that a two-phase excitation state can be obtained at any timing of the time T. Thus, a rotating magnetic field is generated to form the magnetic circuit M1. Thereby, the rotor 4 rotates in the rotation direction cw, and the output shaft 3 rotates continuously.

  In the example of FIG. 5A, the on-time for supplying the second-phase rectangular wave pulse current is overlapped with the on-time for applying the first-phase rectangular wave pulse current for half the pulse width. Energized by shifting, and the pulsed current is continuously energized by shifting the timing one phase at a time. Here, the drive voltage Va is applied to the winding 6a and energized, the drive voltage Vb is applied to the winding 6b and energized, the drive voltage Vc is applied to the coil 6c and energized, and the drive voltage Vd is wound. Apply to the line 6d to energize. Then, the drive voltage Va is applied to the winding 6a and energized so that the ON time when the drive voltage Vb is applied to the winding 6b and energized overlaps with the half of the pulse width. Energization is performed such that the ON time during which Vb is applied to the winding 6b and energized and the ON time during which the drive voltage Vc is applied to the winding 6c overlap with each other for half the pulse width. The energization is performed so that the ON time during which the current is applied to 6c and energized and the ON time during which the drive voltage Vd is applied to the winding 6d are overlapped by half the pulse width.

  As a configuration other than the above, the switched reluctance motor 1 having a built-in position sensor may be a low-side cut and one-side cut circuit (not shown) in which a semiconductor switch is inserted behind the coil by constant current control.

  In FIG. 2, the length of the inner circumference of each stator salient pole 5a, 5b, 5c, 5d facing the rotor salient poles 4a, 4b, 4c is the stator pole width L1, and each stator salient pole 5a, 5b, 5c, 5d. When the distance between the adjacent poles is the stator pole width L2, the stator pole width L1 is larger than the stator pole width L2 (L1> L2). Further, the yoke thickness L3 is the same as or larger than the stator pole width L1 (L3 ≧ L1).

  Further, the outer peripheral surface of each rotor salient pole 4a, 4b, 4c (the surface facing the inner peripheral surface of each stator salient pole 5a, 5b, 5c, 5d) and the inner peripheral surface of each stator salient pole 5a, 5b, 5c, 5d Are opposed to each other, and the air gap G1 between them is set to 0.2 times or less of the stator pole width L2.

  FIG. 3 is a schematic cross-sectional view showing the three-pole rotor 4. On the outer peripheral surface of each rotor salient pole 4a, 4b, 4c (surface facing the inner peripheral surface of each stator salient pole 5a, 5b, 5c, 5d), there is a groove shape toward the P1-P1 line at the center of the output shaft 3 A recess 7 is formed. The opening of the groove-shaped recess 7 is formed at the center of the outer peripheral surface of each rotor salient pole 4a, 4b, 4c, and when the circumferential length on both sides of the opening of the recess 7 is the rotor pole width W1, the rotor pole The width W1 is equal to or larger than the total value of the stator pole width L1 and the stator pole width L2 (W1 ≧ (L1 + L2)). In a cross-sectional view, the shape of the recess 7 is preferably an elliptical shape or a parabolic shape. Thereby, the magnetic circuit M1 which concentrates magnetic flux in the place where the magnetic field intensity around the excitation pole in the rotor 4 is high can be formed.

  When the minimum length from the bottom of the recess 7 to the outer periphery of the output shaft 3 in each rotor salient pole 4a, 4b, 4c is the rotor pole length H1, the rotor pole length H1 is the rotor salient pole 4a, 4b. , 4c on the outer peripheral surface (the surface facing the inner peripheral surface of each stator salient pole 5a, 5b, 5c, 5d facing the P1-P1 line direction) Same or larger than width W1 (H1 ≧ W1). Thereby, it becomes easy to form the magnetic circuit M1.

  Here, the depth of the recess 7 (the minimum length from the opening of the recess 7 to the bottom of the recess 7) is 0.5 times or more the opening width of the recess 7. As a result, the magnetic path length of the magnetic circuit M1 is shortened to reduce the magnetic resistance in each of the rotor salient poles 4a, 4b, 4c.

  As described above, by forming the recess 7 in each of the rotor salient poles 4a, 4b, 4c, the magnetic resistance in the Q1 direction from the P1-P1 line of the output shaft 3 toward the recess 7 and the center P1 of the output shaft 3 There is a difference in the magnetic resistance in the Q2 direction from the -P1 line toward the outer periphery of each of the rotor salient poles 4a, 4b, 4c. As a result, the magnetic flux bypasses the recess 7, and torque for moving the recess 7 to a position facing the stator poles of the stator 5 is generated. Therefore, the rotor 4 can be rotated to a position where the concave portion 7 faces between the stator poles of the stator 5. Since the salient pole of the rotor 4 is in contact with the next stator salient pole at the moment when the concave portion 7 moves to a position facing each stator pole of the stator 5 by the drive circuit 9 described above, the next stator salient pole is excited. As a result, torque is generated and the output shaft 3 continuously rotates. Thereby, the rotor 4 can be started quickly and the output shaft 3 can be rotated continuously.

  In the present embodiment, a pulsed non-sinusoidal current is applied from the DC power source E of the drive circuit 9 to the windings 6a, 6b, 6c, so that the stator salient poles 5a, 5b, 5c, 5d are in a two-phase excitation state. 6d is sequentially energized sequentially to generate a rotating magnetic field to form a magnetic circuit M1, and the rotor 4 is rotated in the rotation direction cw. In the example of FIG. 2, the excited stator salient pole 5a (first salient pole) and the excited stator salient pole 5b (second salient pole) in a state where the winding 6a is energized and the winding 6b is energized. ) And the rotor salient pole 4a (third salient pole) form a magnetic circuit M1. The same applies to the rotor salient pole 4b (third salient pole) and the rotor salient pole 4c (third salient pole).

  As an example other than the above, the rotor 4 may have two poles as shown in FIG. 4A. In this case, the number of poles of the stator 5 is 8. Moreover, as shown to FIG. 4B, it is good also considering the rotor 4 as 4 poles. In this case, the number of poles of the stator 5 is 16. In the present embodiment, the rotor 4 has two or more poles, and the ratio between the number of poles of the rotor 4 and the number of poles of the stator 5 is 1: 4.

(Second Embodiment)
FIG. 6 is a schematic perspective view showing an example of the axial switched reluctance motor 2 of the second embodiment. In the switched reluctance motor 2 of the second embodiment, the rotor 4 is disposed around the P1-P1 line passing through the center of the output shaft 3 (shaft) in the Z direction, and the Z of the rotor 4 is centered on the output shaft 3. A stator 51 is disposed on the upper side in the direction, and a stator 52 is disposed on the lower side in the Z direction of the rotor 4 with the output shaft 3 as the center. Here, the stator 51 having the same structure as the stator 51 and the stator 52 is disposed so as to face each other with the rotor 4 interposed therebetween. In the second embodiment, a description will be given focusing on differences from the first embodiment described above. In addition, when actually using the switched reluctance motor 2, it is not limited to these directions, and it does not interfere even if it uses it in any direction.

  As an example, the rotor 4 and the stator 5 are formed by molding a dust core. As an example, the output shaft 3 is made of steel. Here, the dust core is obtained by coating a crushed iron base material with a resin and molding it by pressure, and has a feature that an eddy current does not occur even when a magnetic flux acts on the structure.

  FIG. 7 is a longitudinal sectional view schematically showing the switched reluctance motor 2 of the second embodiment. Here, one rotor 4 is sandwiched between two stators 5. According to this configuration, the torque is twice the radial gap. On the other hand, the input power is also twice the radial gap. Therefore, a switched reluctance motor 2 that is compact and has extremely large torque and high power can be realized.

  FIG. 8A is a schematic plan view showing the rotor 4, and the rotor salient poles 4a, 4b, 4c are arranged upward in the Z direction. FIG. 8B is a schematic bottom view showing the rotor 4, and the rotor salient poles 4a, 4b, 4c are arranged downward in the Z direction. The rotor 4 has an arrangement configuration in which FIG. 8A and FIG. 8B are back to back, and is displaced by one pole of the stator 5. Here, in FIG. 8A and FIG. 8B, the rotor salient poles 4a, 4b, and 4c are out of phase by 30 [°].

  FIG. 9A is a schematic bottom view showing the stator 51, and the stator salient poles 5a, 5b, 5c, 5d are arranged downward in the Z direction. FIG. 9B is a schematic plan view showing the stator 52, and the stator salient poles 5a, 5b, 5c, 5d are arranged upward in the Z direction. The stator 51 and the stator 52 are arranged so that FIG. 9A and FIG. 9B face each other, and are shifted by one pole of the stator 5. Here, in FIGS. 9A and 9B, the stator salient poles 5a, 5b, 5c and 5d are out of phase by 30 [°].

  In the example shown in FIGS. 8A, 8B, 9A, and 9B, the number of poles of the rotor 4 is 3, the number of poles of the stator 5 is 12, and the number of winding phases is 4. Here, the number of slots of the stator 5 matches the number of salient poles of the stator 5.

  FIG. 10 is a graph showing drive signal waveforms according to the second embodiment. The vertical axis represents voltage V, and the horizontal axis represents time T. As the drive circuit 9, a half bridge circuit shown in FIG. 5B can be applied. In the example of FIG. 10, the on-time for energizing the second-phase rectangular wave pulse-shaped current is energized with the timing shifted so as to overlap the on-time for energizing the first-phase rectangular-wave pulsed current, By continuing this, the current is energized by shifting the timing one phase at a time. Torque ripple is improved by shifting the excitation timing between the stator 51 and the stator 52.

  Here, the drive voltage Va1 and the drive voltage Vd2 have the same phase, the drive voltage Vb1 and the drive voltage Va2 have the same phase, the drive voltage Vc1 and the drive voltage Vb2 have the same phase, and the drive voltage Vd1 and the drive voltage Vc2 Are in phase. According to this, drive control can be performed by one controller. The windings 6a, 6b, 6c, and 6d concentratedly wound around the stator salient poles 5a, 5b, 5c, and 5d are connected in parallel by the stator 51 and the stator 52. Thereby, a large power can be input. In addition to the above, a series connection is also possible.

  As a configuration other than the above, one stator 5 may be disposed so as to face one rotor 4. It is also possible to arrange the two rotors 4 so as to face each other with the stator 5 interposed therebetween.

  The present invention is not limited to the embodiments described above, and various modifications can be made without departing from the present invention. The switched reluctance motor of this embodiment is suitable for a power motor and can also be used as a stepping motor.

1, 2 Switched reluctance motor 3 Output shaft 4 Rotor 4a, 4b, 4c Rotor salient pole 5, 51, 52 Stator 5a, 5b, 5c, 5d Stator salient pole 6a, 6b, 6c, 6d Winding 7 Recess M1 Magnetic circuit

Claims (5)

A rotor in which rotor salient poles are arranged at equal intervals in the circumferential direction around the output shaft, a stator in which stator salient poles are arranged at equal intervals in the circumferential direction around the output shaft, and the stator salient poles Each with a winding wound in a concentrated manner to circulate,
The number of rotor salient poles is n (n is a natural number of 2 or more), the number of stator salient poles is 4n, and the number of phases of the winding is 4,
The adjacent salient poles in each of the stator salient poles are such that the winding directions of the windings are opposite to each other ,
In a state where the winding is energized and the stator salient poles are two-phase excited, the first salient poles of the stator salient poles, and the first salient poles and the rotor adjacent to the predetermined rotation direction. A magnetic circuit is formed by the disposed and excited second salient poles and the third salient poles at positions facing both the first salient poles and the second salient poles of the rotor salient poles,
The length of the portion of the third salient pole facing the second salient pole is larger than the length of the portion of the third salient pole facing the first salient pole. A switched reluctance motor, wherein the third salient pole is in contact with the third salient pole . The switched reluctance motor according to claim 1, wherein a recess facing the center of the output shaft is formed on a surface of the rotor salient pole facing the stator salient pole. The rotor pole length from the concave portion to the output shaft of the rotor salient pole is equal to or larger than the rotor pole width from the concave portion to the end of the rotor salient pole on the surface facing the stator salient pole. The switched reluctance motor according to claim 2. The switched reluctance motor according to any one of claims 1 to 3 , wherein a gap between the rotor and the stator is a radial gap. The switched reluctance motor according to any one of claims 1 to 3 , wherein a gap between the rotor and the stator is an axial gap.

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