JP2008099521A - Switched reluctance motor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a switched reluctance motor having reduced torque ripples. <P>SOLUTION: This switched reluctance motor, forming a plurality of energized phases 8, 9, 10 by winding wirings 2a to 2L, respectively around a plurality of salient poles 1a to 1L of a stator 1, includes a stator 1, having the salient poles 1a to 1L arranged at intervals along a wall surface and formed with a cylindrical space region inwardly by the salient poles 1a to 1L; and a rotor 3 placed rotatably in the space area of the stator 1, where a plurality of salient poles 4a to 4h, having top end surfaces facing the salient poles 1a to 1L of the stator 1 are arranged on the outer circumferential wall. At least one group of the salient poles 1a to 1L of the stator 1 or the salient poles 4a to 4h of the rotor 3 is constituted to have two or more areas with different width dimensions W along a direction in which the rotor 3 rotates. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a switched reluctance motor used as an actuator for various systems of a vehicle, and intends to reduce torque ripple of the motor.

  Switched reluctance motors used as actuators for various vehicle systems incorporate a rotor with a plurality of salient poles inside a stator with a plurality of salient poles. It is constructed by winding a winding around a salient pole, and the rotor is rotated to obtain torque by sequentially energizing each energized phase formed by the winding, and the structure is relatively simple Moreover, since it can be used in special environments such as high-speed rotation and high temperature, interest in various industrial fields including the automobile industry is extremely high.

  By the way, this type of motor has a large torque ripple (torque ripple is the percentage of fluctuation in output torque expressed as a percentage of the average torque), and there is a problem that shaft vibration and noise cannot be avoided, and there is still room for improvement. Has been.

Torque ripple in switched reluctance motors is one of the causes of torque drop due to magnetic saturation near the rotation angle where the rotor salient pole faces the stator salient pole tip. In the prior art, attention has been paid to this, and attempts have been made to suppress magnetic saturation by providing slits on the salient poles of the rotor (see, for example, Patent Document 1). In addition, a technique for reducing torque ripple by providing a concave protrusion at the tip of a rotor salient pole and suppressing magnetic saturation by locally expanding an air gap (see, for example, Patent Document 2) is also known. However, in the prior art, since a slit or an air gap is formed in the magnetic path, the magnetic resistance is increased, and it is possible to avoid a decrease in the inductance change rate with respect to the winding inductance and the rotor rotation angle. There was no situation.
Japanese Patent Laid-Open No. 8-126273 JP 2002-10595 A

Here, the torque T of the switched reluctance motor is, in the magnetic linear region,
T = 1 / 2i ² (dL / dθ) (1)
Since the inductance change rate and the torque are proportional to each other, the conventional technology in which the inductance change rate is reduced has a problem that not only the torque ripple but also the average torque is reduced.

  In addition to magnetic saturation, torque ripple can also be caused by the generation of negative torque at some salient poles. This negative torque can be caused by high-speed rotation driving or low-voltage driving for the following reasons. It is particularly noticeable.

  That is, normally, in order to generate a positive torque in the switched reluctance motor, energization of the winding is started from an angle (rotor angle) at which the rotor salient pole and the stator salient pole start to face each other, Energization is terminated at an angle where the tips of the two faces completely, and since the rate of change in inductance becomes positive in this section, positive torque is generated as is apparent from the above equation (1), but high-speed rotation In the case of driving or low-voltage driving, the change in the winding current with respect to the change in the rotor angle is small. Therefore, in order to allow a sufficient current to flow in a section where the inductance change rate is positive, energization is performed from a nearer angle. Need to start.

  Further, even if the application of the voltage to the winding is stopped near the salient pole facing position, it takes time to decrease the current, so that the current may continue to flow even after passing the facing position. In other words, even when the inductance change rate is negative in order to obtain a sufficient positive average torque, current may flow and negative torque may be generated in a part of the salient pole. As a result, the negative torque cannot be sufficiently reduced simply by increasing the magnetic resistance.

  An object of the present invention is to propose a switched reluctance motor capable of solving the conventional problems as described above.

The present invention has a plurality of salient poles arranged at intervals along a wall surface, and a stator that forms a cylindrical space area inside the salient poles, and is rotatable in the space area of the stator. And a rotor having a plurality of salient poles having tip surfaces opposed to the salient poles of the stator disposed on the outer peripheral wall thereof, and a plurality of windings are wound around each salient pole of the stator. In a switched reluctance motor that forms a current-carrying phase of
The switched reluctance motor is characterized in that at least one of the salient poles of the stator and the rotor has two or more regions having different width dimensions along the rotating direction of the rotor.

  In the switched reluctance motor configured as described above, the salient pole having two or more regions having different width dimensions preferably has a single width center in which the centers of the width dimensions all coincide.

  Moreover, it is preferable that the two or more regions having different width dimensions are provided along the longitudinal direction of the salient pole.

  The salient pole having two or more regions having different width dimensions can be a salient pole of the stator.

Further, the two or more regions having different width dimensions can be arranged in a staggered arrangement between adjacent salient poles, and a wide width part having a large width dimension and a width dimension smaller than the wide width part. consisted of alternating sequences of the narrow portion to, Lc ₁ the axial dimension of the wide _portion, the axial dimension of the narrow portion when the Lc _2, and Lc ₁ and Lc _2, Lc ₂ <ΜLc ₁ / μ ₀ (μ: permeability of material constituting salient poles, μ ₀ : permeability of air) is preferably satisfied, and the axial dimension Lc _{1 of the} wide part and the axis of the narrow part each dimension Lc ₂ is shorter than the axial dimension L of the motor, and the axial dimension Lc ₁ of the wide portion means that the influence of the axial leakage flux is small size.

  When at least one salient pole of the stator and the rotor is provided with a region having two or more different widths with the dimension along the direction of rotation of the rotor as a width dimension, the rotor has a single magnetic path. There are two or more types of salient poles with different torque characteristics with respect to the angle, and the reduction in torque (instantaneous torque) due to negative torque is alleviated and torque ripple is reduced.

  By providing a single width center (the center lines of each salient pole match) of the salient poles having two or more regions having different width dimensions so that the centers of the width dimensions all coincide, the angle of the rotor Since the torque characteristic with respect to is in the opposite phase (the reason will be described later), the reduction in torque (instantaneous torque) due to the negative torque is alleviated to the maximum.

  Two or more regions having different width dimensions are provided along the longitudinal direction of the salient poles. This makes it possible to reflect the torque characteristics of each salient pole at a desired ratio.

  By making the salient poles having two or more regions having different width dimensions as the salient poles of the stator, there is no variation in the width dimension of the salient poles of the rotor. Direction).

  By arranging two or more regions with different width dimensions for the stator salient poles in a staggered arrangement between adjacent salient poles, the space for arranging the windings can be increased. It is possible to reduce the iron loss by increasing the area.

  When two or more regions having different width dimensions are provided on the salient poles of the rotor, the wide width portion having a large width size and the narrow width portion having a smaller width size than the wide width portion are alternately arranged. Therefore, it is possible to suppress the deviation of the center of gravity of the rotor from the center in the longitudinal direction (axial direction), and a mechanically balanced rotation even if the width of the salient pole of the rotor is changed at multiple locations. It becomes possible to be a child.

Hereinafter, the present invention will be described more specifically with reference to the drawings.
FIGS. 1 and 2 are diagrams schematically showing an embodiment of a switched reluctance motor according to the present invention. FIG. 1 is an overall view thereof, and FIG. 2 is a part of a stator cut away from FIG. It is the figure seen from the side (lower side).

  In the figure, 1 is a stator. The stator 1 has a length (axial direction) of L (see FIG. 2), and has 12 salient poles 1a to 1L (angle 30 °) arranged at intervals along the wall surface. A cylindrical space region is formed inside the salient poles 1a to 1L.

  Further, 2a to 2L are windings wound around the salient poles 1a to 1L of the stator 1, and 3 is a rotor arranged in the space region of the stator 1. Although not shown, the rotor 3 is supported by a bearing and is rotatably held in the space region.

Reference numerals 4a to 4h are eight salient poles that are integrally provided on the outer peripheral wall of the rotor 3 at an angle of 45 ° and that have tip surfaces facing the salient poles 1a to 1L of the stator 1. The salient poles 4a~4h two types of width t of the direction in which the rotation of the rotor 3 is different (t _1, t ₂ at _{t 1>} t ₂₎ in the region _{L 1, L 2 (L =} L 1 + L 2 (Refers to the dimension along the longitudinal direction (axial direction) of the salient poles 4a to 4h. See FIG. 2).

  The motor having the above configuration can be provided with a drive circuit as shown in FIG. 3, for example. In FIG. 3, 5a to 5f are switching elements, 6a to 6f are diodes, 7 is a DC power supply, and 8 is a U phase. Winding, 9 is a V-phase winding, and 10 is a W-phase winding. For example, the U-phase winding 8 is configured as windings 2a, 2d, 2g, and 2j connected in parallel, and the V-phase winding 9 is configured as connecting windings 2b, 2e, 2h, and 2k in parallel. Further, the W-phase winding 10 is configured by connecting the windings 2c, 2f, 2i, and 2L in parallel.

  The U-phase winding 8, the V-phase winding 9, and the W-phase winding 10 constitute a general half-bridge circuit, and the above three phases are driven by the DC power source 7, and the switching elements 5a to 5f are In accordance with a winding current peak command value and a winding current hysteresis width command value from a control device (not shown), switching is performed so that the current waveform has a substantially rectangular wave shape.

  FIG. 4 shows an example of the current waveform of the winding current with respect to the rotation angle of the rotor 3 when the rotor 3 is energized to output the maximum torque when rotating at a constant speed near the specified rotation. It is.

For example, in the U-phase winding 8, the rotation angle of the rotor 3 is θon The switching elements 5a and 5b are turned on and energization is started from that point, and when the winding current peak command value ip is reached, the switching elements 5a and 5b are turned off and the current is reduced by the hysteresis width command value ihsy. After that, the switching elements 5a and 5b are turned on again, the current is increased to the winding current peak command value ip, and is controlled to substantially DC near the ip, and switching is performed when the rotation angle θ of the rotor 3 becomes θoff. The elements 5a and 5b are turned off to obtain a waveform as shown in FIG.

  The V-phase winding 9 and the W-phase winding 10 are energized in the same manner to obtain the same current waveform, but the V-phase winding 9 is delayed by 120 ° in electrical angle from the U-phase winding 8. Thus, the W-phase winding 10 is delayed by 240 ° in electrical angle.

  Here, for example, in order to generate a positive torque in the motor by the winding current of the U-phase winding 8, the stator 1 around which the windings 2a, 2d, 2g, 2j constituting the U-phase winding 8 are wound Starting from the angle θu (see Fig. 4) where the salient poles 1a, 1d, 1g, 1j of the rotor and any salient pole of the rotor 1 are completely non-opposing, the salient poles of both are completely facing each other It is desirable to end the energization at an angle θa (see FIG. 4) at which the tips face each other. That is, θon = θu, θoff = θa (the angle θ of the rotor 1 is such that the salient pole of the stator 1 around which the U-phase winding 8 is wound and the salient pole of the rotor 1 face each other. The angle is 0 °, and the same direction as the rotation direction is positive).

  By the way, in the switched reluctance motor, when the rotational speed is high (high speed) or when the voltage of the DC power supply 7 is low, the rate of change of the current (winding current) with respect to the angle change of the rotor 3 is small. In order to obtain a sufficient current at the angle θu shown in FIG. 4, it is necessary to set θon to an angle smaller than θu in consideration of a delay in the rise of the current. It is necessary to make θoff at a small angle, and such a driving condition (θon <θu, θoff <θa) is also applied to the switched reluctance motor according to the present invention.

FIG. 5 shows a torque waveform when the motor according to the present invention is energized and driven with a current waveform according to the above conditions. The solid line in FIG. 5 is the torque waveform of the motor according to the present invention, and the one-dot chain line and the two-dot chain line indicate the width dimension t of the salient poles 4a to 4h of the rotor 3 in the longitudinal direction (axial direction) for comparison. This is a torque waveform of the switched reluctance motor, where t ₁ and t ₂ (t ₁ > t ₂ ).

A rotor having a torque characteristic of the motor width throughout the axial direction is provided with a rotor 3 having a salient pole becomes t _1, the salient pole width is the width becomes t ₂ in the overall Jikute direction Although the torque characteristics of the motor with 3 are in opposite phases, the motor according to the present invention has both torque characteristics and can reduce torque ripple while maintaining the average torque. .

Torque characteristics of a motor having a rotor 3 having a salient pole whose width dimension is t ₁ (hereinafter, this motor is referred to as motor A) and a rotor 3 having a salient pole whose width dimension is t ₂ The reason why the torque characteristics of the motor (hereinafter referred to as “motor B”) are in opposite phases is explained as follows.

  FIG. 6 is a diagram showing the distribution of electromagnetic forces of the motors A and B at the rotation angle θA of the rotor 3 shown in FIG. At the rotation angle θA, the torque of the motor A is the maximum value and the torque of the motor B is the minimum value as shown in FIG.

  At the rotation angle θA, the salient pole of the motor A is in a position where it begins to face the salient pole 1a of the stator 1 around which the U-phase winding is wound, and a large positive torque is generated. On the other hand, the salient pole of the rotor 3 of the motor B is still far away from the salient pole 1a of the stator 1, and the generated positive torque is small. Thus, due to the difference in the distance from the salient pole of the stator 1, the magnitude of the torque differs between the two.

  Next, FIG. 7 shows the distribution of electromagnetic forces of the motors A and B at the rotation angle θB of the rotor 3 shown in FIG. When the rotation angle of the rotor 3 is θB, the torque of the motor A is the minimum value and the torque of the motor B is the maximum value as shown in FIG. 5. Here, the salient pole of the motor A is the stator 1 A positive torque is generated by facing the salient pole 1a to some extent, but a magnetic path is also formed between the salient pole 1b around which the V-phase winding is wound and a negative torque is also generated. ing. On the other hand, the salient pole of the rotor 3 of the motor B is in a position where it begins to face the salient pole 1a of the stator 1, and a large positive torque is generated. Little torque is generated.

  In this way, torque ripple can be reduced by providing salient poles having a width dimension in which the torque characteristics are in opposite phases.

  In the above example, a motor provided with salient poles having two types of width dimensions has been described. However, regions having different width dimensions can be increased as necessary, and this is not a limitation. Moreover, the influence margin of the torque characteristic can be adjusted by appropriately changing the ratio in the longitudinal direction (axial direction) of the regions having different width dimensions.

  FIG. 8 shows another embodiment of the present invention in which two types of regions having different width dimensions t are provided on the salient poles 1a to 1L of the stator 1, and the salient poles adjacent to each other are alternately arranged. .

  In the configuration including the stator 1 having such a configuration, not only can the torque ripple of the motor be reduced, but also there is an advantage that the space for winding can be expanded.

The winding is wound so as to fit in a gap (strot) formed between the salient poles of the stator 1, but the opening angle of the slot is θ ₁ + θ _{2 by} staggering regions having different width dimensions. Thus, the space can be expanded by θ ₂ as compared with the conventional structure, so that the cross-sectional area of the winding can be increased and the iron loss is reduced.

FIG. 9 shows that each of the salient poles 4a to 4f of the rotor 3 has two regions having different width dimensions t, a wide part t ₃ having a large width dimension, and a smaller dimension than the wide part t _3. to constituted by the narrow portion t _4, it is of the configuration which are arranged alternately along it in its longitudinal direction. Even in a motor provided with the rotor 3 having such a configuration, torque ripple can be reduced.

The rotor 3 has dimensions Lc ₁ and Lc ₂ along the axial direction (longitudinal direction) of the salient poles of the wide part t ₃ and the narrow part t ₄ smaller than the width dimension of the wide part t _3. it becomes possible to minimize the influence of the leakage magnetic flux in the longitudinal direction of the salient poles to be larger than the width dimension of the width portion t _4, the center of gravity of the rotor 3 is present in the center in the axial direction Therefore, there is an advantage that the mechanical balance is not impaired even if the width dimension of the salient pole is changed at a plurality of positions.

The axial dimension Lc ₂ axial dimension Lc ₁ and the narrow portion t ₄ of the wide portion t ₃ In the present invention, it is assumed to satisfy the relationship of Lc _{2 <μLc 1 /} μ ₀ is preferred, because It is as follows.

When the axial dimension Lc ₁ of the wide portion t ₃ results in too small and leaks out magnetic flux in the air layer around the (material constituting a laminated steel plate (salient poles) becomes thin, the magnetic resistance (magnetic flux This is because the air resistance is increased and the air layer is easier to pass.) By satisfying the above conditions, the magnetic resistance when passing through the laminated steel sheet passes through the air layer. It becomes possible to make it smaller than the magnetic resistance when doing.

Here, the above conditions are as follows: the protrusion allowance of the salient pole is w, 1/2 of the difference between the two width dimensions of the salient pole is r, the permeability of the laminated steel plate (member constituting the rotor) is μ, air When the permeability of μ is ₀ ,
w / μLc ₁ r (magnetoresistance of Lc ₁ convex steel plate) <w / μ ₀ Lc ₂ r (reluctance air magnetoresistance) ⇒ Lc ₂ <μLc ₁ / μ ₀
by.

  A stable reluctance motor with reduced torque ripple can be stably supplied.

It is the figure which showed typically embodiment of the switched reluctance motor according to this invention. FIG. 2 is a diagram in which a part of the stator of the motor shown in FIG. 1 is cut. It is the figure which showed the drive circuit of the switched reluctance motor. It is the figure which showed the electric current waveform and the torque waveform. It is the figure which showed the torque waveform at the time of driving the torque waveform at the time of driving the switched reluctance motor according to this invention, and the switched reluctance motor which has a salient pole which has a fixed width | variety. It is the figure which showed distribution of electromagnetic force. It is the figure which showed distribution of the electromagnetic force of the motor provided with the stator which has a salient pole of a fixed width. It is the figure which showed other embodiment of the switched reluctance motor according to this invention. It is the figure which showed other embodiment of the switched reluctance motor according to this invention.

Explanation of symbols

1 Stator
1a ~ 1L salient pole
2a ~ 2L winding
3 rotor
4a ~ 4h Salient pole
5a to 5f switching element
6a ~ 6f Diode 7 DC power supply
8 U phase winding
9 V phase winding
10 W phase winding

Claims (6)

A stator having a plurality of salient poles arranged at intervals along the wall surface and forming a cylindrical space area inside the salient poles, and an outer periphery of the stator rotatably arranged in the space area of the stator A rotor provided with a plurality of salient poles having tip surfaces facing the salient poles of the stator on a wall, and winding a plurality of energized phases by winding a winding around each salient pole of the stator. In the formed switched reluctance motor,
The switched reluctance motor, wherein at least one salient pole of the stator and the rotor has two or more regions having different width dimensions along a direction in which the rotor rotates.   2. The switched reluctance motor according to claim 1, wherein the salient poles having two or more regions having different width dimensions have a single width center in which the centers of the width dimensions all coincide.   3. The switched reluctance motor according to claim 1, wherein the two or more regions having different width dimensions are provided along a longitudinal direction of the salient pole.   The switched reluctance motor according to any one of claims 1 to 3, wherein the salient poles having two or more regions having different width dimensions are salient poles of a stator.   5. The switched reluctance motor according to claim 4, wherein the two or more regions having different width dimensions are arranged in a staggered arrangement between adjacent salient poles. The two or more regions having different width dimensions are composed of an alternating arrangement of a wide portion having a large width dimension and a narrow portion having a smaller width dimension than the wide portion,
When the axial dimension of the wide part is Lc ₁ and the axial dimension of the narrow part is Lc ₂ , Lc ₁ and Lc ₂ are
Lc ₂ <μLc ₁ / μ ₀ (μ: permeability of material constituting salient pole, μ ₀ : permeability of air)
The switched reluctance motor according to claim 3, wherein the switched reluctance motor is satisfied.

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