JP2006254621A - Permanent magnet type motor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a low-vibration/low-noise motor which reduces cogging torque or torque pulsation by lessening the change of magnetic resistance by the rotational position of a rotor. <P>SOLUTION: This motor is equipped with a stator where a plurality of teeth are made radially from an annular yoke, leaving spaces to serve as winding groovesin its circumferential direction, and a rotor which faces the above stator via a small air gap and is retained rotatably and generates a field by permanent magnets embedded in a rotor core and the air gap between which and the stator at a section proximate to the intermediate between the magnetic poles of the rotor core is wide. Herein, sections, where the air gaps to the stator positioned on the peripheral side more than the permanent magnet of the rotor core are narrow, are skewed in its circumferential direction. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an embedded magnet type electric motor in which a permanent magnet is embedded in a rotor core.

  A conventional electric motor is configured as shown in FIG. This is composed of a stator and a rotor that is rotatably supported facing the stator in the radial direction. The stator iron core is formed of teeth on which windings are applied and a substantially annular yoke that connects the teeth. At the tip of the teeth, a tooth tip protrusion that protrudes in the circumferential direction along the gap with the opposing rotor is formed. A plurality of permanent magnets for generating a field are embedded in the rotor in the radial direction of the rotor core.

In order to reduce cogging torque and torque pulsation, the rotor blocks divided into two in the axial direction are stacked while being shifted in the circumferential direction. (For example, see Patent Document 1)
JP 2000-308287 A

  When a permanent magnet is embedded in the rotor core as in the above-described conventional configuration, the magnetic resistance increases in the direction of the magnetic flux generated by the permanent magnet because it crosses the permanent magnet, whereas in the direction of 90 degrees in electrical angle. Since the magnetic flux passes through the core part of the rotor, the magnetic resistance is lowered. As described above, in the structure in which the permanent magnet is embedded in the rotor, a difference occurs in the magnetic resistance depending on the relative position between the rotor and the stator, so that the cogging torque and the torque pulsation when driving the motor tend to increase. Thereby, the vibration and noise as an electric motor deteriorate.

  Further, in order to reduce the change in magnetic resistance due to the relative position of the rotor and the stator, a means is taken in which the rotor is divided in the axial direction and is laminated while being shifted in the circumferential direction. However, when the rotor is divided in the axial direction, the magnetic flux distribution changes stepwise with respect to the axial direction, so there is a limit to reducing the cogging torque. Further, if the number of rotor divisions is increased in order to smooth the magnetic flux distribution, axial magnetic flux leakage occurring at the boundary of each stage increases, and the output of the motor decreases.

  The present invention solves such a conventional problem, and a low-vibration and low-noise motor that reduces cogging torque and torque pulsation by reducing changes in magnetic resistance due to the rotational position of the rotor. The purpose is to provide.

  In order to solve the above-described problems, the present invention provides a stator in which a plurality of teeth are radially formed with a circumferential interval between an annular yoke and a winding groove, and a small gap between the stator and the stator. The magnetic field is generated by a permanent magnet embedded in a rotor core that is held in a rotatable manner and is laminated in the axial direction with thin electromagnetic steel plates laminated in the axial direction. In an electric motor provided with a rotor having a wide gap between the rotor and the stator and a rotor core located on the outer peripheral side of the permanent magnet having a narrower portion than the gap between the magnetic poles, the outer periphery of the permanent magnet The narrow part of the gap with the stator of the rotor core located on the side is skewed in the circumferential direction.

  In addition, a narrow portion of the gap with the stator located outside the permanent magnet of the rotor core is skewed in the circumferential direction, and the skew angle is an angle corresponding to one pitch of the stator slots.

  Further, a narrow portion of the gap with the stator located on the outer peripheral side of the permanent magnet of the rotor core is skewed in the circumferential direction, and the skew angle has an angle corresponding to one cycle of an arbitrary order of torque pulsation. It is.

  In addition, a stator in which a plurality of teeth are radially formed with a circumferential interval as an annular yoke and a winding groove is opposed to the stator via a slight gap, and is rotatably held. The field is generated by the permanent magnet embedded in the rotor core, and the gap between the rotor and the stator in the vicinity between the magnetic poles of the rotor core is widened and is located on the outer peripheral side of the permanent magnet. In a multi-phase full-wave drive motor equipped with a rotor core that has a rotor that is narrower than the gap between the magnetic poles, the gap between the rotor core and the stator located on the outer peripheral side of the permanent magnet The narrow portion is skewed in the circumferential direction, and the skew angle is 360 / (Φ × 2) × 2 / p degree (Φ is the number of driving phases and p is the number of poles of the rotor).

  In addition, a stator in which a plurality of teeth are radially formed with a circumferential interval as an annular yoke and a winding groove is opposed to the stator via a slight gap, and is rotatably held. The field is generated by the permanent magnet embedded in the rotor core, and the gap between the rotor and the stator in the vicinity between the magnetic poles of the rotor core is widened and is located on the outer peripheral side of the permanent magnet. In a multi-phase half-wave drive motor provided with a rotor core that has a rotor that is narrower than the gap between the magnetic poles, the gap between the rotor core and the stator located on the outer peripheral side of the permanent magnet The narrow portion is skewed in the circumferential direction, and the skew angle is 360 / Φ × 2 / p degrees (Φ is the number of driving phases, and p is the number of rotor poles).

  Further, in an embedded magnet type electric motor in which a rotor core is divided into a plurality of parts in the axial direction and these are shifted in the circumferential direction and stacked in the axial direction, the stator core is positioned on the outer peripheral side of the permanent magnet of the rotor core. The narrow gap is skewed in the circumferential direction.

  Further, the rotor core has a portion in which a plurality of electromagnetic steel plates having the same shape as viewed from the axial direction are stacked, and the skew applied to the rotor core is configured in a stepped manner.

  By the above means, the distribution of magnetic flux generated from the rotor is dispersed in the circumferential direction, so that cogging torque and torque pulsation can be reduced. As a result, noise and vibration when the motor is driven can be suppressed.

  According to the first aspect of the present invention, the magnetic flux generated from the permanent magnet is dispersed in the circumferential direction by skewing the narrow portion of the gap with the stator on the outer circumferential side from the permanent magnet of the rotor core in the circumferential direction. Can do. Therefore, cogging torque and torque pulsation during driving are reduced by an easy method without dividing the permanent magnet in the axial direction, and noise and vibration during operation can be reduced.

  According to the second aspect of the present invention, since the relative positions of the rotor and the stator are uniformly distributed so that there is no coincidence in any cross section perpendicular to the axis, the cogging torque is reduced. Can be reduced.

  According to the third aspect of the present invention, it is possible to effectively reduce a desired harmonic component among the noise and vibration of the electric motor.

  According to the fourth aspect of the present invention, in a multi-phase full-wave driven motor, the minimum order component of harmonics having the greatest influence on vibration generated by torque pulsation as an excitation source is efficiently reduced. Therefore, it is possible to reduce the vibration and noise of the motor driven by the multi-phase full wave.

  According to the fifth aspect of the present invention, in the motor driven by the multiphase half wave, the minimum order component that is the harmonic with the largest amplitude of the torque pulsation can be efficiently reduced. The motor driven by can reduce vibration and noise.

  According to the sixth aspect of the present invention, when the rotor is divided into a plurality of blocks in the axial direction and they are stacked while being shifted in the circumferential direction, the outer peripheral side of the rotor core is fixed. By skewing the narrow part of the gap with the rotor in the circumferential direction, the discontinuous change in the magnetic flux generated between the blocks can be alleviated, so the magnetic flux distribution is smoothed even if the number of rotor divisions is small. It is possible to suppress the leakage magnetic flux in the axial direction between the rotor blocks, and to increase the output of the electric motor in addition to reducing vibration and noise.

  In addition, according to the seventh aspect of the invention, since it has a portion in which a plurality of electromagnetic steel sheets having the same shape as viewed from the axial direction are laminated, the types of electromagnetic steel sheets constituting the rotor can be reduced, and the rotor can be easily manufactured. it can.

  According to the invention described in claims 8 to 10, it is possible to reduce the noise and vibration of household electrical appliances and automobiles.

  The present invention has a stator in which a plurality of teeth are radially formed at circumferential intervals to be an annular yoke and a winding groove, and is opposed to the stator via a slight gap so as to be rotatable. A magnetic field is generated by a permanent magnet embedded in a rotor core that is held and laminated in the axial direction with thin magnetic steel sheets laminated in the axial direction, and the gap between the rotor and stator in the vicinity of the magnetic poles of the rotor core In an electric motor provided with a rotor having a rotor core located on the outer peripheral side of the permanent magnet and a rotor having a narrower portion than the gap between the magnetic poles, the rotation positioned on the outer peripheral side of the permanent magnet The narrow part of the gap between the stator core and the stator is skewed in the circumferential direction.

  Further, a portion where the gap between the stator core and the stator located outside the permanent magnet is narrow is skewed in the circumferential direction, and the skew angle is an angle corresponding to one pitch of the teeth of the stator.

  In addition, a portion having a narrow gap with the stator located on the outer peripheral side of the permanent magnet of the rotor core is skewed in the circumferential direction, and the skew angle has an angle corresponding to one cycle of an arbitrary order of torque pulsation. It is.

  In addition, a stator in which a plurality of teeth are radially formed with a circumferential interval as an annular yoke and a winding groove is opposed to the stator via a slight gap, and is rotatably held. The field is generated by the permanent magnet embedded in the rotor core, and the gap between the rotor and the stator in the vicinity between the magnetic poles of the rotor core is widened and is located on the outer peripheral side of the permanent magnet. In a multi-phase full-wave drive motor equipped with a rotor core that has a rotor that is narrower than the gap between the magnetic poles, the gap between the rotor core and the stator located on the outer peripheral side of the permanent magnet The narrow portion is skewed in the circumferential direction, and the skew angle is 360 / (Φ × 2) × 2 / p degree (Φ is the number of driving phases and p is the number of poles of the rotor).

  In addition, a stator in which a plurality of teeth are radially formed with a circumferential interval as an annular yoke and a winding groove is opposed to the stator via a slight gap, and is rotatably held. The field is generated by the permanent magnet embedded in the rotor core, and the gap between the rotor and the stator in the vicinity between the magnetic poles of the rotor core is widened and is located on the outer peripheral side of the permanent magnet. In a multi-phase half-wave drive motor provided with a rotor core that has a rotor that is narrower than the gap between the magnetic poles, the gap between the rotor core and the stator located on the outer peripheral side of the permanent magnet The narrow portion is skewed in the circumferential direction, and the skew angle is 360 / Φ × 2 / p degrees (Φ is the number of driving phases, and p is the number of rotor poles).

  Further, in an embedded magnet type electric motor in which a rotor core is divided into a plurality of parts in the axial direction and these are shifted in the circumferential direction and stacked in the axial direction, the stator core is positioned on the outer peripheral side of the permanent magnet of the rotor core. The narrow gap is skewed in the circumferential direction.

  Further, the rotor core has a portion in which a plurality of electromagnetic steel plates having the same shape as viewed from the axial direction are stacked, and the skew applied to the rotor core is configured in a stepped manner.

  With such a configuration, since the magnetic flux generated from the permanent magnet of the rotor can be dispersed in the circumferential direction, cogging torque and torque pulsation can be reduced.

  More specific embodiments of the present invention will be described with reference to the drawings.

As shown in FIG. 1, the electric motor according to the first aspect of the present invention has a plurality of teeth 3 formed radially at intervals in the circumferential direction to be an annular yoke 1 and a slot 2 which is a winding groove. The stator 4 is opposed to the stator 4 with a slight gap, is held rotatably, and is bounded by a permanent magnet 6 embedded in a rotor core 5 in which thin electromagnetic steel plates are laminated in the axial direction. Generate magnetism. The rotor 7 has a wide gap between the rotor and the stator in the vicinity of the magnetic poles of the rotor core, and a portion 8 narrower than the gap between the magnetic poles exists on the outer peripheral side of the permanent magnet. In the above electric motor, the portion 8 having a narrow gap with the stator located on the outer peripheral side of the permanent magnet of the rotor core is skewed in the circumferential direction.
Fig. 2 shows the distribution of the gap magnetic flux density between the stator and the rotor for the rotor in which the position of the narrow gap between the rotor core and the stator differs in the circumferential direction. Here, a is the magnetic pole center of the permanent magnet, and b is the position of the rotor having the narrowest gap with the stator or the center position of the rotor core where the gap with the stator is the narrowest. In FIG. 2, the angles formed by a and b (with the rotation direction being positive) are represented by three electrical angles of −15 °, 0 °, and + 15 ° with respect to the magnetic pole of the permanent magnet. Thus, it can be seen that the center position where the magnetic flux density takes an extreme value (the center of the magnetic flux distribution) changes to a position equal to the position where the gap of the rotor is the narrowest. Thus, the gap magnetic flux density distribution between the stator and the rotor is also dispersed by skewing the iron core portion on the outer peripheral side of the permanent magnet of the rotor core in the circumferential direction. Accordingly, since the magnetic resistance is dispersed in the circumferential direction without matching the axial direction at any arbitrary rotational position, the attractive force generated between the stator and the rotor is dispersed, and cogging torque and torque pulsation are reduced. .

  In the electric motor according to the second aspect of the present invention, the skew angle 9 of the rotor core is set to an angle corresponding to one slot pitch of the stator.

  Here, the cogging torque is a circumferential component of the magnetic attractive force of the rotor and the stator. The stator has a slot 2 and a tooth 3 into which a winding is inserted. As an example, considering the position at the center of the magnetic flux by the permanent magnet of the rotor as a reference, the magnetic resistance is high at the position facing the slot, and the magnetic resistance is low at the position facing the tooth. Therefore, the center of the magnetic pole of the rotor receives a force in the direction attracted to the teeth of the stator.

  By setting the skew angle of the rotor core to an angle corresponding to one slot pitch, the center of the rotor magnetic pole faces all the positions of both the slot and the tooth. As a result, the magnetic resistance at an arbitrary position of the rotor is uniformly distributed with respect to the axial direction, so that the cogging torque is reduced.

  In the electric motor according to claim 3 of the present invention, when the order component of vibration or noise to be reduced is W, the skew angle 9 of the rotor core is set to 360 / W degrees corresponding to one cycle of the W-order component. Is. As a result, torque pulsation of the W-order component can be reduced, so that vibration and noise of the W-order component can be effectively reduced.

  In the electric motor according to claim 4 of the present invention, in the multi-phase full-wave drive electric motor, a narrow gap between the stator and the stator located on the outer peripheral side of the permanent magnet of the rotor core is skewed in the circumferential direction. The skew angle is 360 / (Φ × 2) × 2 / p degree (Φ is the number of driving phases, and p is the number of poles of the rotor). In a three-phase full-wave drive motor, a 60 ° periodic torque pulsation is generally generated in terms of electrical angle. This torque pulsation is often the basic order of torque waveform distortion. Therefore, by applying a skew angle that cancels a harmonic having one cycle of 360 / (Φ × 2) × 2 / p degree (Φ is the number of driving phases and p is the number of poles of the rotor), Harmonics can be reduced, and the motor noise and vibration performance is greatly improved.

  Similarly, in an electric motor driven by five-phase full waves, torque pulsations with a period of 360 ° / (5 phases × 2) = 36 ° in electrical angle are the main harmonics.

  The electric motor according to claim 5 of the present invention is a multiphase half-wave drive electric motor, wherein a narrow gap with a stator located on the outer peripheral side of the permanent magnet of the rotor core is skewed in the circumferential direction, The skew angle is 360 / Φ × 2 / p degrees (Φ is the number of driving phases, and p is the number of rotor poles). In a three-phase half-wave drive electric motor, torque pulsations with an electrical angle of 120 ° are generally generated. This torque pulsation is often the basic order of torque waveform distortion, and reducing the harmonics of this order greatly improves the performance of the motor against noise and vibration.

  As shown in FIG. 3, the electric motor according to claim 6 of the present invention is a motor in which the rotor core is divided into a plurality of parts in the axial direction and the rotor blocks are stacked skewed in the circumferential direction. A portion 8 having a narrow gap with the stator located on the outer peripheral side of the permanent magnet 6 of the iron core 5 is skewed in the radial direction. In a rotor configured by stacking rotor blocks having the same rotor core shape as seen from a cross section perpendicular to the axis as shown in the conventional example, the position of the permanent magnet is set in the radial direction by each rotor block. Since they are stacked in a shifted manner, the magnetic flux generated by the permanent magnets is shifted in the radial direction, and there is an effect of dispersing the attractive force with the rotor. However, since the change in magnetic flux between the rotor blocks becomes large and discontinuous, the magnetic flux distortion here causes torque pulsation. Therefore, the maximum position of the magnetic flux density is continuously changed with respect to the axial direction by skewing the shape of the rotor core in the circumferential direction so that the shape gradually changes at the boundary of the rotor block. Therefore, cogging torque and torque pulsation are reduced, and the motor can be reduced in vibration and noise.

  As shown in FIG. 4, the electric motor according to claim 7 of the present invention has a portion in which the rotor core 5 has a portion in which a plurality of electromagnetic steel plates having the same shape as viewed from the axial direction are laminated, and the skew applied to the rotor core. Is configured in a staircase pattern. By adopting such a configuration, the types of electrical steel sheets constituting the rotor are reduced, so a rotor having the effect of reducing cogging torque and torque pulsation by dispersing the magnetic flux distribution can be obtained with simple equipment. In addition, it can be easily manufactured with less man-hours.

  In the above configuration, noise and vibration during operation can be suppressed by reducing cogging torque and torque pulsation during driving. In recent years, the demand for low noise and low vibration has been increasing for air conditioners mounted on home appliances and automobiles. Therefore, by applying the electric motor of the present invention to these devices, noise can be reduced. And home appliances and automobiles with low vibration.

  The electric motor of the present invention is useful as a power source with low vibration and low noise.

Electric motor of first embodiment of the present invention, (a) sectional view, (b) perspective view Diagram showing air gap magnetic flux density distribution The perspective view which shows the rotor of the 6th Example of this invention. The perspective view which shows the rotor of the 7th Example of this invention. Conventional motor, (a) perspective view showing electric motor, (b) perspective view showing rotor.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Yoke 2 Slot 3 Teeth 4 Stator 5 Rotor core 6 Permanent magnet 7 Rotor 8 A part with a narrow space | gap with a stator 9 Skew angle

Claims (10)

A stator in which a plurality of teeth are radially formed with a circumferential interval to be an annular yoke and a winding groove, and is opposed to the stator via a slight gap and is rotatably held, and is a thin plate Field is generated by a permanent magnet embedded in the rotor core, which is formed by laminating electromagnetic steel sheets in the axial direction, and the gap between the rotor and the stator in the vicinity between the magnetic poles of the rotor core is wide and permanent. In an electric motor including a rotor core positioned on the outer peripheral side of the magnet and a rotor having a portion narrower than the gap between the magnetic poles, the rotor core positioned on the outer peripheral side of the permanent magnet A permanent magnet electric motor characterized in that a narrow portion of the gap is skewed in the circumferential direction. A portion having a narrow gap with the stator located outside the permanent magnet of the rotor core is skewed in the circumferential direction, and the skew angle is an angle corresponding to one pitch of the slots of the stator. The permanent magnet motor according to claim 1. A portion having a narrow gap with the stator located on the outer peripheral side of the permanent magnet of the rotor core is skewed in the circumferential direction, and the skew angle is an angle corresponding to one cycle of an arbitrary order of torque pulsation. The permanent magnet motor according to claim 1, wherein the motor is a permanent magnet motor. A stator in which a plurality of teeth are radially formed with an annular yoke and a winding groove spaced apart from each other, and is opposed to the stator through a slight gap, and is rotatably held and rotated. A field is generated by a permanent magnet embedded in the core of the rotor, and the gap between the rotor and stator in the vicinity of the rotor core is wide, and the rotor core located on the outer periphery of the permanent magnet Is a multi-phase full-wave drive motor equipped with a rotor having a narrower part than the gap between the magnetic poles, and the part where the gap between the stator and the stator located on the outer peripheral side of the rotor core is narrower in the circumferential direction The skew angle is 360 / (Φ × 2) × 2 / p degree (Φ is the number of driving phases and p is the number of poles of the rotor). The permanent magnet motor described. A stator in which a plurality of teeth are radially formed with an annular yoke and a winding groove spaced apart from each other, and is opposed to the stator through a slight gap, and is rotatably held and rotated. A field is generated by a permanent magnet embedded in the core of the rotor, and the gap between the rotor and stator in the vicinity of the rotor core is wide, and the rotor core located on the outer periphery of the permanent magnet Is a multi-phase half-wave drive motor equipped with a rotor having a narrower part than the gap between the magnetic poles, and the part where the gap between the stator and the stator located on the outer peripheral side of the rotor core is narrower in the circumferential direction 2. The permanent magnet according to claim 1, wherein the skew angle is 360 / Φ × 2 / p degrees in mechanical angle (Φ is the number of driving phases and p is the number of poles of the rotor). Electric motor. In an embedded magnet type electric motor in which a rotor core is divided into a plurality of parts in the axial direction and these are shifted in the circumferential direction and stacked in the axial direction, there is a gap between the rotor core and the stator located on the outer peripheral side of the permanent magnet of the rotor core. 6. The permanent magnet motor according to claim 1, wherein the narrow portion is skewed in the circumferential direction. The rotor core has a portion in which a plurality of electromagnetic steel sheets having the same shape as viewed from the axial direction are laminated, and the skew applied to the rotor core is configured in a step shape. 6. The permanent magnet motor according to 6. A hermetic compressor equipped with the electric motor according to claim 1. A refrigeration cycle using the hermetic compressor according to claim 8. An air conditioner comprising the refrigeration cycle according to claim 9.

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