JP4791325B2 - Synchronous motor, air conditioner and ventilation fan - Google Patents

Description

  The present invention relates to a synchronous motor provided with a rotor using a magnet, and relates to a synchronous motor that realizes low cost, high efficiency, and low noise, and an air conditioner, a ventilation fan, and a hermetic compressor using the same. Is.

  In a synchronous motor using a magnet as a rotor, in order to suppress pulsation of output torque, it is necessary to make an induced voltage generated in the motor sinusoidal. In order to make the induced voltage sinusoidal, the magnetic flux density on the rotor surface has a sinusoidal distribution.

For example, the ring-shaped magnet of the rotor is cylindrical and the outer peripheral surface facing the pole teeth and the auxiliary pole of the stator is magnetized with a plurality of magnetic poles along the outer peripheral surface so that the adjacent magnetic poles N and S have different polarities, A concave portion is provided at an intermediate position between adjacent different polarities N and S, and the central portions of the magnetic poles N and S are formed as convex surfaces. There has been proposed a motor whose magnetization is a sine waveform on an apparent line equidistant from the pole teeth of the stator (see, for example, Patent Document 1).
JP 2002-262491 A

  To make the distribution of magnetic flux density on the rotor surface sinusoidal, for example, the shape of the magnet placed on the rotor surface is made thicker at the center of the magnetic pole, and the thickness gradually decreases between the magnetic poles. May take shape. In this case, the maximum value of the magnetic flux density in the gap between the rotor and the stator when the rotor and the stator are combined, in other words, the amplitude of the magnetic flux density distributed in a sinusoidal shape is determined by the thickness of the magnet. Therefore, in order to increase the magnetic flux density, it is necessary to increase the thickness of the magnet, and there is a problem that the amount of magnet used increases.

  Further, in order to obtain a larger amount of magnetic flux generated from the rotor, it can be realized by bringing the distribution of the magnetic flux density on the surface closer to a rectangle (trapezoid). However, in this case, the harmonic component contained in the induced voltage increases, and the torque pulsation becomes large, causing vibration and noise.

  The present invention has been made to solve the above-described problems, and a synchronous motor that can improve output and efficiency without increasing vibration and noise, an air conditioner using the same, and a ventilator. An object is to provide a blower and a hermetic compressor.

  A synchronous motor according to the present invention includes a rotor having a magnet, the number of magnetic poles being p (even), and a stator having an n (integer greater than or equal to 2) phase winding, the rotor and the stator, In the synchronous motor having a gap between, the magnetic flux density waveform of the gap includes a harmonic component of 1/2 × p × n × m (m is an odd number) order more than other harmonic components. To do.

  The synchronous motor according to the present invention generates torque even if the maximum value of the magnetic flux density is the same by including a harmonic component of 1/2 × p × n × m order in the magnetic flux density waveform of the air gap. Therefore, it is possible to include a large number of 1/2 × p-order frequency components necessary for the above, and it is possible to increase the torque and the efficiency of the synchronous motor. In addition, since the harmonic components of 1/2 × p × n × m order cancel each other in the n-phase stator winding and do not appear in the induced voltage, no extra torque pulsation occurs. Does not increase vibration and noise.

Embodiment 1 FIG.
1 to 4 are diagrams showing the first embodiment. FIG. 1 is a perspective view of a rotor 20 of a synchronous motor, FIG. 2 is a partial sectional view of the rotor 20 of the synchronous motor, and FIG. 3 is a stator (not shown). 1) and the synchronous motor rotor 20 are combined to show the magnetic flux density distribution in the air gap (portion between the stator and the rotor), and FIG. It is a figure which shows the relationship between the amplitude of the wave of the period comprised by the following frequency component and one magnetic pole pair.

  As shown in FIG. 1, the rotor 20 of the synchronous motor shown in this embodiment has a magnet 1 divided for each magnetic pole arranged on the surface of a yoke 2 made of a magnetic material. The magnet 1 is fixed to the surface of the yoke 2 by bonding or molding. A shaft 21 is fitted to the center of the yoke 2. The rotor 20 of the synchronous motor shown in FIG. 1 uses eight magnets 1 divided for each magnetic pole. The material of the magnet 1 is generally sintered ferrite.

  Each of the magnets 1 has an arc shape along the surface shape of the ring-shaped yoke 2 on the inner peripheral surface. The outer peripheral surface has a generally arc shape that protrudes outward, but is not a simple shape. This embodiment is characterized by the shape of the outer peripheral surface of the magnet 1. Details will be described below.

  As shown in FIG. 2, the cross-sectional shape of the magnet 1 is recessed in the vicinity of the magnetic pole center 3. As the distance from the magnetic pole center 3 increases, the thickness in the radial direction gradually increases within a predetermined range on both sides of the magnetic pole center 3 and reaches the maximum thickness on both sides 4 of the magnetic pole center. Further, the radial thickness gradually decreases from both sides 4 of the magnetic pole center to both ends of the magnet 1. On both sides 4 of the magnetic pole center having the maximum thickness, the distribution of the magnetic flux density of the air gap is also maximized.

  FIG. 3 shows the magnetic flux density distribution of the air gap when the stator (not shown) and the synchronous motor rotor 20 are combined. FIG. 3 shows a magnetic flux density waveform of the gap for one magnetic pole pair (for two poles), and the radial thickness of the magnet 1 at the magnetic pole center 3 is smaller than the radial thickness at both sides 4 of the magnetic pole center. As a result, the magnetic flux density at the magnetic pole center 3 is lowered, and the magnetic flux density waveform of the air gap becomes a waveform 5 including the first and third frequency components. The waveform 5 including the first-order and third-order frequency components includes more third-order frequency components than other harmonic components.

  In FIG. 3, the waveform 5 including the primary and tertiary frequency components includes a primary component that is one cycle with one magnetic pole pair and a tertiary component that is a component of three times the frequency. is there. When the waveform 5 including the primary and tertiary frequency components is compared with the waveform 6 including only the primary component, the maximum values are substantially the same, but the waveform 1 including the primary and tertiary frequency components includes 1 The amplitude of the next component 7 is larger than that of the waveform 6 including only the first component, as indicated by a broken line in the figure.

  As a result, the primary component included in the induced voltage generated in the stator winding (not shown) also increases. Since the torque generated from the synchronous motor is generated by the product of the induced voltage and current of the winding, a larger torque can be obtained when the same current is passed. Alternatively, since less current is required to output the same torque, the loss (copper loss) generated in the winding is reduced and the efficiency of the motor is improved.

  In the case of a three-phase motor, even if a third-order frequency component is included in the magnetic flux density waveform of the air gap, the induced voltage of the stator cancels out the third-order frequency component between the phases. This frequency component does not appear. For this reason, pulsation does not occur in the output torque, and generation of vibration and noise can be suppressed.

  Thus, in a synchronous motor having a three-phase stator winding, the magnetic flux density waveform of the air gap contains more primary and tertiary components than the other harmonic components in the period waveform composed of one magnetic pole pair. As a result, the output of the synchronous motor can be improved, the efficiency can be improved, and at the same time, the generation of vibration and noise of the synchronous motor can be suppressed.

  In FIG. 4, the horizontal axis represents the ratio (harmonic content rate) of the component of the magnetic flux density distribution of the gap of one magnetic pole pair, and the horizontal axis indicates the ratio of the magnetic flux density distribution of one magnetic pole pair. The graph which took the ratio (fundamental wave amplitude ratio) of the amplitude of the primary component with respect to the maximum amplitude of a waveform on the vertical axis | shaft is shown. By including a third-order component in the magnetic flux density distribution of the air gap, the first-order component included in the waveform can be increased. A range 8 in which the primary component is increased by 10% or more with respect to the amplitude value of the waveform is when the tertiary component is contained by 9 to 28%. Among them, the range 9 in which the primary component becomes the largest is when the tertiary component is contained in an amount of 14 to 20%.

  In the present embodiment, the surface magnetic flux distribution of the rotor magnet 1 is shown in which only a primary component and a tertiary component are included in the waveform of the period formed by one magnetic pole pair. Double harmonics may be included.

  Moreover, although the synchronous motor having a three-phase stator winding has been described as an example, it is not limited to three phases. The stator winding may have any number of phases.

  From the above, if the number of poles of the rotor is p (even), the number of phases of the stator winding is n (an integer of 2 or more), and m is an odd number, the surface magnetic flux density waveform of the rotor is 1/2 × p. By including many harmonic components of × n × m order, the output and efficiency of the synchronous motor can be improved, and at the same time, the generation of vibration and noise of the synchronous motor can be suppressed.

Embodiment 2. FIG.
5 to 7 are diagrams showing the second embodiment. FIG. 5 is a partial sectional view of the rotor 20 of the synchronous motor. FIG. 6 is a perspective view of the magnet 1 used for the rotor 20 of the synchronous motor. It is a perspective view of the magnet 1 used for the rotor 20 of an electric motor.

  In the rotor 20 of the synchronous motor of the present embodiment, a ring-shaped magnet 1 is disposed on the surface of a magnetic yoke 2. The magnet 1 is magnetized or oriented in the radial direction.

  There is a groove 3a (a cross-sectional shape is substantially U-shaped and formed in the axial direction) on the outer periphery of each magnetic pole center 3 of the ring-shaped magnet 1, and only the groove 3a portion has a thickness in the radial direction of the magnet 1. Is thinner. As a result, the magnetic flux density at the magnetic pole center 3 is lowered, and the air gap magnetic flux density distribution waveform is the same as in FIG. By changing the shape of the groove 3a (the length in the circumferential direction and the depth in the radial direction), the third order component included in the magnetic flux density waveform of the air gap can be changed and optimized.

  If the thickness of the magnet 1 (the portion without the groove 3a) is determined, the maximum value of the magnetic flux density on the magnet surface is also determined. Even if the maximum magnetic flux density is the same, by providing the groove 3a at the magnetic pole center 3, the primary component contained in the magnetic flux density waveform of the air gap becomes larger than when there is no groove 3a, and the synchronous motor has a higher torque and higher power. Efficiency can be improved.

  The magnetic flux density distribution of the air gap can be adjusted by the shape of the yoke used for magnetizing the magnet 1 and the applied current. Alternatively, the magnetic flux density distribution of the air gap can also be adjusted by changing the axial length of the magnet 1 and adjusting the amount of magnetic flux linked to the stator winding. For example, as shown in FIG. 6, by providing notches 10 between the magnetic poles at both ends in the axial direction between the magnetic poles, a change in the amount of magnetic flux is represented by, for example, a waveform 5 including the primary and tertiary frequency components in FIG. It is also possible to adjust as follows.

  Further, instead of providing the groove 3a in the magnetic pole center 3 as shown in FIG. 7, by providing notches 11 in the magnetic pole center at both ends in the axial direction of the magnetic pole center 3, the change in the amount of magnetic flux It is also possible to adjust like the waveform 5 including the primary and tertiary frequency components in FIG.

Embodiment 3 FIG.
8 and 9 are diagrams showing the third embodiment, FIG. 8 is a perspective view of the rotor 20 of the synchronous motor, and FIG. 9 is a cross-sectional view showing the direction of magnetization of the magnet 1 used in the rotor 20 of the synchronous motor. It is.

  As shown in FIG. 8, the point that the ring-shaped magnet 1 is arranged on the surface of the magnetic yoke 2 is the same as in the second embodiment. In the present embodiment, an isotropic material (rare earth magnet) is used for the magnet 1, and both sides 4 of the magnetic pole center rather than the magnetic pole center 3 are shown in FIG. Magnetization is performed so that the magnetic flux is concentrated on.

  As a result, the magnetic flux density distribution on the rotor surface has a waveform that takes a peak on both sides 4 of the magnetic pole center rather than 3. In this way, the distribution waveform of the magnetic flux density in the air gap is adjusted so as to have a waveform containing a large amount of primary and tertiary components, so that the synchronous motor can generate vibration and noise. High torque and high efficiency can be achieved while suppressing.

Embodiment 4 FIG.
10 and 11 are diagrams showing the fourth embodiment. FIG. 10 is a perspective view of the rotor 20 of the synchronous motor. FIG. 11 is a cross-sectional view showing the orientation of the magnet 1 of the rotor 20 of the synchronous motor. .

  Unlike Embodiments 1 to 3 described above, the rotor 20 of the synchronous motor does not use a magnetic body (yoke 2) as a magnetic path. The magnet 1 is coupled to the shaft 21 by a connecting portion 22 formed of resin or the like. An anisotropic material magnet 1 is used, and an extremely anisotropic magnetic field is applied when the magnet 1 is formed. As a result, an anisotropic orientation is made inside the magnet 1, and a sufficient amount of magnetic flux can be obtained without the magnetic yoke 2 between the magnet 1 and the shaft 21.

  Since the thickness of the magnet 1 is increased, as a material, sintered ferrite or a plastic magnet is often used. The waveform of the magnetic flux density distribution on the rotor surface can be adjusted by the distribution of the orientation magnetic field during molding. Therefore, as shown in FIG. 11A, by adjusting the orientation of the magnet 1, the magnetic flux is concentrated on both sides 4 of the magnetic pole center 3 as shown in FIG. It is possible to achieve a surface magnetic flux density waveform that contains a large amount of, and to improve torque and efficiency while suppressing vibration and noise of the synchronous motor.

Embodiment 5 FIG.
FIG. 12 shows the fifth embodiment and is a cross-sectional view of the rotor 20 of the synchronous motor.

  In the rotor 20 of the synchronous motor of the present embodiment, the magnet 1 is disposed in the magnet insertion hole 23 inside the magnetic rotor. As the magnet 1, a rare earth magnet is often used. This is a rotor that utilizes reluctance torque using the magnetic body portion 12 on the outer periphery of the magnet 1 disposed in the magnet insertion hole 23.

  A groove 3a (the cross-sectional shape is substantially U-shaped and formed in the axial direction) is provided in the magnetic pole center 3 on the outer periphery of the magnetic body portion 12 on the outer peripheral portion of the magnet 1. Since the portion of the groove 3a has a large distance (gap length) from the stator, the magnetic flux generated from the magnet 1 flows on both sides 4 of the magnetic pole center on both sides of the groove 3a, and the shape and dimensions of the groove 3a. Thus, a rotor having a gap magnetic flux density distribution as shown in FIG. 3 can be obtained. As a result, a gap magnetic flux density distribution containing a large amount of primary components can be realized, and torque and efficiency can be improved while suppressing vibration and noise of the synchronous motor.

  The rotor 20 of the synchronous motor according to the present embodiment is particularly suitable for a hermetic compressor. Since a rare earth magnet is used, it has high performance and the magnet 1 is inserted into the magnet insertion hole 23 inside the rotor, so that it is suitable for use in a hermetic compressor.

Embodiment 6 FIG.
FIG. 13 is a diagram illustrating the air conditioner 30 according to the sixth embodiment.

  The synchronous motor using the synchronous motor rotor 20 shown in the first to fifth embodiments is mounted. The synchronous motor is mainly used for the compressor motor 14 of the outdoor unit 13, the blower motor 15, and the blower motor 17 of the indoor unit 16.

  Most of the electric power consumed by the air conditioner 30 is generated by the compressor motor 14, the blower motor 15, and the blower motor 17, and is synchronized using the rotor 20 of the synchronous motor according to the first to fifth embodiments. By using an electric motor for these, power consumption can be reduced while suppressing vibration and noise generated from the air conditioner 30.

Embodiment 7 FIG.
FIG. 14 shows the seventh embodiment and is a front view of the ventilation fan 40.

  The ventilation blower 40 includes a blower motor 18 serving as a drive source, and blades 19 driven by the blower motor 18. Since the blower motor 18 rotates the blades 19 directly, the torque pulsation of the blower motor 18 tends to cause vibration and noise.

  By using the rotor 20 of the synchronous motor of Embodiments 1 to 5 for the blower motor 18, the ventilation blower 40 with reduced power consumption can be obtained while suppressing vibration and noise.

  Further, since the efficiency is high, heat generation from the blower motor 18 is reduced, the life of the bearing of the blower motor 18 is extended, and the life of the blower motor 18 can be extended.

  Further, since the torque can be increased, the blower motor 18 can be downsized. In this case, the ventilation fan 40 can be reduced in weight.

It is a figure shown in Embodiment 1, and is a perspective view of the rotor 20 of a synchronous motor. It is a figure shown in Embodiment 1, and is a fragmentary sectional view of the rotor 20 of a synchronous motor. It is a figure shown in Embodiment 1, and is a figure which shows the magnetic flux density distribution of a space | gap when a stator and the rotor 20 of a synchronous motor are combined. FIG. 5 is a diagram illustrating the relationship between the higher-order frequency component included in the waveform of the surface magnetic flux density of the rotor 20 of the synchronous motor and the amplitude of a wave having a period composed of one magnetic pole pair, according to the first embodiment. . It is a figure which shows Embodiment 2, and is a fragmentary sectional view of the rotor 20 of a synchronous motor. It is a figure which shows Embodiment 2, and is a perspective view of the magnet 1 used for the rotor 20 of a synchronous motor. It is a figure which shows Embodiment 2, and is a perspective view of the magnet 1 used for the rotor 20 of a synchronous motor. It is a figure which shows Embodiment 3, and is a perspective view of the rotor 20 of a synchronous motor. It is a figure which shows Embodiment 3, and is sectional drawing which shows the direction of the magnetization of the magnet 1 used for the rotor 20 of a synchronous motor. It is a figure which shows Embodiment 4, and is a perspective view of the rotor 20 of a synchronous motor. It is a figure which shows Embodiment 4, and is sectional drawing which shows the direction of orientation of the magnet 1 of the rotor 20 of a synchronous motor. It is a figure which shows Embodiment 5, and is sectional drawing of the rotor 20 of a synchronous motor. It is a figure which shows Embodiment 6, and is a figure which shows the air conditioner 30. FIG. It is a figure which shows Embodiment 7, and is a front view of the air blower 40 for ventilation.

Explanation of symbols

  1 Magnet, 2 Yoke, 3 Magnetic pole center, 4 Both sides of magnetic pole center, 5 Waveform including primary and tertiary frequency components, 6 Waveform including only primary components, and 7 Waveform including primary and tertiary frequency components 8 The primary component included in the range, 8 The range in which the primary component is greater than 10%, 9 The range in which the primary component is the largest, 10 Notch between the magnetic poles, 11 Notch in the center of the magnetic pole, 12 Magnetic unit, 13 outdoor unit, 14 motor for compressor, 15 motor for blower, 16 indoor unit, 17 motor for blower, 18 motor for blower, 19 blades, 20 rotor of synchronous motor, 21 shaft, 22 connecting portion , 23 Magnet insertion hole, 30 Air conditioner, 40 Blower for ventilation.

Claims (4)

In a synchronous motor having a magnet, including a rotor having a number of magnetic poles p (even) and a stator having a three-phase winding, and having a gap between the rotor and the stator,
In the magnetic flux density waveform of the air gap, the first-order component and the third-order component or the harmonic component that is an odd multiple of the third-order component are included in the waveform of the period formed by one magnetic pole pair more than the other harmonic components,
The rotor is arranged by dividing the magnet into magnetic poles on the outer peripheral surface of a magnetic yoke, and the magnet has a generally convex outer shape on the outer peripheral surface and a concave portion in the vicinity of the magnetic pole center. As the distance from the magnetic pole center increases, the thickness in the radial direction gradually increases within a predetermined range on both sides of the magnetic pole center, and reaches a maximum thickness on both sides of the magnetic pole center. The synchronous motor is characterized in that the radial thickness gradually decreases and the thickness of the magnet from the magnetic pole center to both end portions changes smoothly.   2. The synchronous motor according to claim 1, wherein the waveform of the period formed by the one magnetic pole pair includes a tertiary component in an amount of 14 to 20%. An air conditioner characterized by being mounted to one of the synchronous motor according to claim 1 or 2 wherein. Ventilating fan, which comprises using in claim 1 or 2 blower electric motor to one of the synchronous motor according.

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