JP2000217287A - Permanent magnet type motor and compressor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a permanent magnet type motor and a compressor that can reduce torque ripples in the permanent magnet type motor with a rotor where a nearly plate-shaped permanent magnet is fitted to the inside of a rotor core, while the permanent magnet orthogonally crosses a diameter direction, and a compressor where the motor is mounted. SOLUTION: A void part 18 extending near an outer surface 15b of a rotor core 15 is formed at each end part 16a of a permanent magnet 16 in the rotor core 15. Furthermore, a thickness dimension (t) of a bridge part 19 between an internal surface 18a of the void part 18 and the external surface 15b of the rotor core 15 is set, so that the thickness dimension is reduced from the side of the end part 16a of the permanent magnet 16 toward the side of the adjacent permanent magnet 16.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a permanent magnet type motor provided with a rotor having a substantially plate-shaped permanent magnet mounted in a direction perpendicular to a radial direction inside a rotor core, and a motor mounted with the same. Related to compressors.

[0002]

As for a permanent magnet type motor, a motor having a structure shown in FIG. 16 has recently been developed to achieve higher torque and higher efficiency. That is, the stator 1 is configured by mounting the stator windings 3 on the stator core 2. The rotor 4 is rotatably provided inside the stator 1 with a small gap G therebetween. The rotor 4 is configured by mounting, for example, four permanent magnets 6 on a rotor core 5. More specifically, the rotor core 5 is provided with four magnet-arranging holes 5a of a substantially rectangular shape which are orthogonal to the radial direction at every 90 degrees, and a plate is formed in the magnet-arranging hole 5a. A permanent magnet 6 is fitted and fixed. These four permanent magnets 6 are magnetized such that N poles and S poles alternate. Note that reference numeral 7 is a rotation axis.

However, in the above-described conventional configuration, the magnetic field B _L (see FIG. 17) generated from the ends of the adjacent permanent magnets 6 having different polarities short-circuits the rotor core 5 as a magnetic path.
The magnetic flux linking the stator windings 3 is reduced, and there is a problem that the motor performance is reduced.

In order to improve this, it is considered that the rotor 4 is configured as shown in FIG. That is, in the rotor core 5, substantially rectangular gaps 5b and 5b are formed at both end portions of the respective permanent magnets 6 so as to extend toward the outer surface side of the rotor core 5, so that short-circuit magnetic flux is reduced. .

However, in this case, as shown in FIG. 19, the magnetic flux density distribution in the air gap between the stator 1 and the rotor 4 has a rectangular wave shape, the torque ripple becomes large, and vibration and noise are generated. Is done. In particular, when a rare-earth magnet is used as the permanent magnet 6, because of high performance, the waveform of the magnetic flux density distribution in the air gap between the stator and the rotor becomes a clearer rectangular waveform, and the torque ripple increases. Further, when the above-described motor is mounted on a compressor of an air conditioner or a refrigerator, there is a problem that the operating sound of the air conditioner and the refrigerator is loud especially when used at night.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a rotor constituted by mounting a substantially plate-shaped permanent magnet in a form orthogonal to a radial direction inside a rotor core. It is an object of the present invention to provide a permanent magnet type motor and a compressor which can reduce torque ripple and reduce vibration and noise in a permanent magnet type motor provided and a compressor equipped with this type of motor.

[0007]

According to a first aspect of the present invention, there is provided a stator in which a plurality of phases of stator windings are mounted on a stator core, and a configuration in which a rotor core is orthogonal to a radial direction. A permanent magnet type motor comprising: a rotor having a substantially plate-shaped permanent magnet mounted thereon; and a rotor rotatably disposed inside a stator core of the stator. At each end portion, a gap is formed which extends to near the outer surface of the rotor core, and the thickness of the portion between the inner surface of the gap and the outer surface of the rotor core is adjusted to the permanent magnet adjacent to the permanent magnet end side. The feature is that it is set so as to decrease toward the magnet side.

[0008] In the above configuration, since a gap is formed at each end portion of the permanent magnet in the rotor core so as to extend near the outer surface of the rotor core, a short circuit of the magnetic field between the end portions of adjacent permanent magnets is prevented. Will be prevented. As a result, the amount of magnetic flux linking the stator windings increases, and the motor characteristics can be improved.

Further, the thickness dimension of the portion between the inner surface of the gap and the outer surface of the rotor core is set so as to decrease from the end of the permanent magnet toward the adjacent permanent magnet.
The magnetic flux density distribution in the air gap between the stator and the rotor can be made sinusoidal, in particular with reduced harmonic components, torque ripple is reduced, and vibration and noise are reduced. The invention according to claim 2 is characterized in that the degree of reduction in the thickness dimension of the portion between the inner surface of the gap and the outer surface of the rotor core decreases on the adjacent permanent magnet side. With this configuration, the strength of the portion between the inner surface of the gap and the outer surface of the rotor core can be increased.

According to a third aspect of the present invention, there is provided a stator constituted by mounting a plurality of phases of stator windings on a stator core, and a substantially plate-shaped permanent magnet inside the rotor core in a form orthogonal to the radial direction. A permanent magnet type motor comprising a magnet mounted thereon and comprising a rotor rotatably disposed inside a stator core of the stator, wherein each end portion of the permanent magnet in the rotor core includes: A gap is formed that extends near the outer surface of the rotor core, and the dimension from the center of the rotor core to the outer surface of the rotor is reduced from the end of the permanent magnet toward an intermediate portion between adjacent permanent magnets. There is a characteristic in the setting as described above.

[0011] In the above configuration, since a gap is formed at each end of the permanent magnet in the rotor core so as to extend near the outer surface of the rotor core, a magnetic field short-circuit between the ends of adjacent permanent magnets is prevented. Will be prevented. As a result, the amount of magnetic flux linking the stator windings increases, and the motor characteristics can be improved.

Further, the dimension from the center of the rotor core to the outer surface of the rotor is set so as to decrease from the end of the permanent magnet toward the intermediate portion between the adjacent permanent magnets. The magnetic flux density distribution in the air gap with the element can be made sinusoidal, especially with reduced harmonic components, torque ripple is reduced, and vibration and noise are reduced.

According to a fourth aspect of the present invention, there is provided a stator constituted by mounting a plurality of phases of stator windings on a stator core, and a substantially plate-shaped permanent magnet inside the rotor core in a form orthogonal to the radial direction. A permanent magnet type motor comprising a magnet mounted thereon and comprising a rotor rotatably disposed inside a stator core of the stator, wherein each end portion of the permanent magnet in the rotor core includes: A gap is formed which extends to near the outer surface of the rotor core, and the end of the permanent magnet pole at the center of the gap at one end of the permanent magnet and the end of the permanent magnet at the gap at the other end. The opening angle with respect to the center end of the rotor core with respect to the center of the rotor core is 90 to 13 in electrical angle.
The feature is that it is set to be less than 0 degrees.

[0014] In this configuration, since a gap is formed at each end portion of the permanent magnet in the rotor core so as to extend near the outer surface of the rotor core, short-circuit of the magnetic field between the ends of adjacent permanent magnets is prevented. Will be prevented. As a result, the amount of magnetic flux linking the stator windings increases, and the motor characteristics can be improved.

[0015] Further, the rotation of the end of the permanent magnet pole center side in the gap on one end side of each permanent magnet and the end of the permanent magnet pole center side in the gap on the other end side. Since the opening angle with respect to the center of the iron core was set to be an electrical angle of 90 or more and less than 130 degrees, the magnetic flux density distribution in the air gap between the stator and the rotor, particularly, harmonic components were reduced. It is possible to form a sine wave, torque ripple is reduced, and vibration and noise are reduced.

The invention according to claim 5 is characterized in that the permanent magnet is made of a rare earth magnet. In this configuration, since the permanent magnet is made of a rare-earth magnet, an improvement in torque can be expected, and an increase in torque ripple can be eliminated even though the rare-earth magnet is used as the permanent magnet.

A sixth aspect of the present invention is characterized in that a driving means for supplying a sinusoidal current to the plural-phase stator winding is provided. In this configuration, the winding current becomes a sine wave, and the torque ripple can be further reduced.

A seventh aspect of the present invention is characterized in that the gap portion is provided with a slip stopper which comes into contact with the end of the permanent magnet. With this configuration, even though there are gaps at both ends of the permanent magnet, the permanent magnet can be reliably stopped from moving.

The compressor according to the invention of claim 8 is a suction means for supplying a gasket to the compression space, a compression means for compressing the gasket supplied into the compression space, and a drive means for driving the compression means. It is characterized in that the permanent magnet type motor according to any one of the above and a discharge means for discharging a compressed gasket are provided. Compressors are often mounted in air conditioners and refrigerators, and are required to have low noise from the viewpoint of night use. However, in the compressor of this configuration,
Since the above-described permanent magnet type motor of the present invention is mounted,
It is extremely effective for noise reduction.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described below with reference to FIGS. First, FIG. 3 shows a permanent magnet type motor 10. In FIG. 1, a stator 11 includes teeth 12 a of a stator core 12.
And a plurality of phases of stator windings 13 mounted thereon. The rotor 14 is rotatably provided inside the stator 11 with a small gap G therebetween. The rotor 14 has four permanent magnets 16 attached to the rotor core 15 at, for example, 90 degrees.
Is configured. Specifically, the rotor core 15
And four substantially rectangular magnet arrangement holes 15a which are orthogonal to the radial direction are formed in the magnet arrangement holes 1a.
A plate-shaped permanent magnet 16 is fitted and fixed to 5a. These four permanent magnets 16 are magnetized such that N poles and S poles alternate. This permanent magnet 16 is made of a rare earth magnet. Note that reference numeral 17 is a rotation axis.

As shown in FIGS. 1 and 2, at each end 16a of the permanent magnet 16 in the rotor core 15, there is formed a gap 18 extending to a position near the outer surface 15b of the rotor core 15. ing. The thickness t of a portion 19 (hereinafter referred to as a bridge portion 19) between the inner surface 18a of the gap 18 and the outer surface 15b of the rotor core 15
From the end 16a side of the permanent magnet 16
It is set to decrease continuously toward the sixth side. The thickness t is smallest at an intermediate portion (indicated by reference numeral C) between the adjacent permanent magnets 16, 16. The two-dot chain line j in FIG. 1 shows a case where the thickness dimension is constant as a reference for thickness comparison. In addition, each gap 18
Is formed with a convex slip stopper 20 so as to abut the end 16 a of the permanent magnet 16.

The permanent magnet type motor 10 configured as described above is mounted on a compressor 21 as shown in FIG. Describing the compressor 21, a compression mechanism 25 as a compression means having a pair of rollers 23 and 24 is incorporated in a lower portion of the casing 22. The compression mechanism 25 sucks low-pressure refrigerant gas in the accumulator 26 into a gasket compression space 29 through a suction pipe 27 and a suction port 28 corresponding to suction means by rotation of rollers 23 and 24. Due to the reduction in the volume of the gas compression space 29, the refrigerant gasket is compressed and then discharged into the casing 22 via a discharge pipe (not shown) serving as a discharge means.

The above-described motor 10 is incorporated above the compression mechanism 25. The stator 11 is a casing 2
2, and the stator winding 13 (not shown in FIG. 4) is configured to be able to conduct electricity through a terminal (not shown) provided in the power supply connection portion 30. Further, the rotor 14 and the rollers 23 and 24 are connected to the rotation shaft 17 described above.

FIG. 5 shows a control circuit of the motor 10. An inverter main circuit 32 is connected between both terminals of the DC power supply 31. This inverter main circuit 32
For example, switching elements 32a to 32 such as transistors
f is connected in a three-phase bridge, and return diodes 33a to 33
f are connected in parallel with the polarity shown. Each output terminal of the inverter main circuit 32 has a stator winding 13
Are connected to the respective phase windings 13u, 13v, 13w.

The control circuit 34 includes the inverter main circuit 32
And the driving means 35, and the control circuit 34
Is configured to include a microcomputer and the like.
This control circuit 34 controls each phase winding 13 of the stator winding 13.
The rotational position of the rotor 11 is detected by detecting the induced voltages generated at u, 13v, and 13w, and the phase windings 13u, 13u are detected based on the position detection.
The power is cut off at the appropriate timing between v and 13w. In this case, each phase winding 13u, 13v, 13w
, A sine wave current is supplied. That is, for example, regarding the U-phase winding 13u, as shown in FIG. 6A, a sinusoidal signal wave vau is generated with respect to the carrier wave Pz.
Is superimposed to generate a drive signal Dup, which is a PWM signal, as shown in FIG. 11B, and based on this, the switching elements 32a to 32f of the inverter main circuit 32 are switched to thereby generate a drive signal Dup. ), A sine-wave current is supplied to the U-phase winding 13u.

According to the permanent magnet type motor 10 described above, each end 16 of the permanent magnet 16 in the rotor core 15
Since a gap portion 18 is formed in the portion a to extend near the outer surface 15b of the rotor core 15, the adjacent permanent magnets 1 are formed.
6 can be prevented from short-circuiting between the end portions 16a. As a result, the amount of magnetic flux linking the stator winding 13 increases, and the motor characteristics can be improved.

Further, the thickness t of the bridge portion 19 between the inner surface 18a of the gap 18 and the outer surface 15b of the rotor core 15 is directed from the end portion 16a of the permanent magnet 16 to the adjacent permanent magnet 16 side. As shown in FIG. 7, the distribution of the magnetic flux density in the minute gap G (see FIG. 3) between the stator 11 and the rotor 14 is reduced to a substantially sinusoidal value in which the harmonic components are reduced. It can be wavy, torque ripple is reduced, and vibration and noise can be greatly reduced.

According to the present embodiment, since the permanent magnet 16 is made of a rare-earth magnet, an improvement in torque can be expected. Since the magnetic flux density distribution of G can be made sinusoidal, an increase in torque ripple can be eliminated.

Further, according to this embodiment, since the driving means 35 for supplying a sine wave current to the stator windings 13 of a plurality of phases is provided, the winding current of each phase becomes a sine wave, and the torque ripple can be further reduced. Become like Furthermore, according to the present embodiment, since the gap 18 is provided with the slip stopper 20 which is in contact with the end 16 of the permanent magnet 16, the gap 18 is provided at both ends 16 a and 16 a of the permanent magnet 16. The movement of the permanent magnet 16 can be reliably stopped. And
According to the compressor 21 equipped with the above-described motor 10, noise can be sufficiently reduced.

FIGS. 8 and 9 show a second embodiment of the present invention. In this embodiment, adjacent permanent magnets 1 are used.
Rotor core 1 in bridge section 19 between 6 and 16
(5) The point that the dimension Q of the outer surface 15b from the center P of the rotor 14 is continuously shortened from the end portion 16a of each permanent magnet 16 toward the intermediate portion C between the adjacent permanent magnets 16. Is different from the first embodiment. As a result, the rotor core 15
The intermediate portion C of the outer surface 15b is slightly concave. Note that the two-dot chain line j ′ indicates the outer surface 1 of the rotor core 15.
The case where 5b has a constant radius is shown for reference. In the second embodiment, the same effects as those of the first embodiment can be obtained.

FIG. 10 shows a third embodiment of the present invention. In this embodiment, a bridge portion 19 between the inner surface 18a of the gap 18 and the outer surface 15b of the rotor core 15 is shown.
Is characterized in that the degree of decrease in the thickness dimension t is smaller on the side of the adjacent permanent magnet 16 (the portion is indicated by reference numeral 19 '). According to this embodiment, the strength of the bridge portion 19 between the inner surface 18a of the gap 18 and the outer surface 15b of the rotor core 15 can be increased.

FIG. 11 shows a fourth embodiment of the present invention. In this embodiment, a bridge portion 19 between an inner surface 18a of a gap 18 and an outer surface 15b of a rotor core 15 is shown.
The difference from the first embodiment is that the degree of decrease in the thickness dimension t of the first embodiment gradually decreases. Also in this embodiment, a substantially sinusoidal magnetic flux density distribution is obtained as a whole, and vibration and noise can be reduced as compared with the conventional case.

FIGS. 12 to 15 show a fifth embodiment of the present invention. This embodiment differs from the first embodiment in the following points. That is, each of the gaps 41A and 41B is formed in a substantially triangular shape, and one end 16 of each of the permanent magnets 16 is formed.
The end 41Aa of the A-side gap 41A on the magnetic pole center side of the permanent magnet 16 and the end 41Ba of the gap 41B on the other end 16B side of the permanent magnet 16 on the magnetic pole center side,
The opening angle θ based on the center P of the rotor core 15 is set to be an electrical angle of 90 degrees or more and less than 130 degrees.

The purpose of this setting is as follows. In FIG.
The experiment results of the present inventor show how the ratio [%] of the third harmonic component of the magnetic flux density distribution in the minute gap G changes when the opening angle θ is changed. In this case, the ratio of the third harmonic component is +20.
% And -20% or less (negative phase is opposite), it cannot be expected that the magnetic flux density distribution becomes sinusoidal. However, as can be seen from the figure, the opening angle θ at which the ratio of the third harmonic component is 20% or less in absolute value is in the range indicated by the symbol K, but is 9 electrical degrees in view of safety margin.
What is necessary is just 0 degree or more and less than 130 degrees. As a result, FIG.
As shown in FIG. 5, the magnetic flux density distribution becomes substantially sinusoidal, torque ripple is reduced, and vibration and noise are reduced.

[0035]

As is apparent from the above description, the present invention provides a permanent magnet having a rotor constituted by mounting a substantially plate-shaped permanent magnet in a form perpendicular to the radial direction inside a rotor core. In a type motor and a compressor equipped with this type of motor, the torque ripple can be reduced, and vibration and noise can be reduced.

[Brief description of the drawings]

FIG. 1 is a plan view of a gap portion of a rotor showing a first embodiment of the present invention.

FIG. 2 is a plan view of a rotor.

FIG. 3 is a plan view of a motor.

FIG. 4 is a cutaway side view of the compressor.

FIG. 5 is an electric circuit diagram

FIG. 6 is a waveform chart for explaining a sinusoidal current.

FIG. 7 is a diagram showing a magnetic flux density distribution between a stator and a rotor.

FIG. 8 is a view corresponding to FIG. 2, showing a second embodiment of the present invention;

FIG. 9 is a diagram corresponding to FIG. 1;

FIG. 10 is a view corresponding to FIG. 1, showing a third embodiment of the present invention.

FIG. 11 is a view corresponding to FIG. 1, showing a fourth embodiment of the present invention;

FIG. 12 is a view corresponding to FIG. 2, showing a fifth embodiment of the present invention;

FIG. 13 is a diagram corresponding to FIG. 1;

FIG. 14 is a diagram showing a relationship between an opening angle and a ratio of a third harmonic component.

FIG. 15 is a diagram showing a magnetic flux density distribution between a stator and a rotor.

FIG. 16 is a diagram corresponding to FIG. 3 showing a conventional example.

FIG. 17 is a diagram corresponding to FIG. 2;

FIG. 18 is a diagram corresponding to FIG. 2, showing a different conventional example.

FIG. 19 is a diagram showing a magnetic flux density distribution between a stator and a rotor.

[Explanation of symbols]

10 is a permanent magnet type motor, 11 is a stator, 12 is a stator core, 13 is a stator winding, 14 is a rotor, 15 is a rotor core, 16 is a permanent magnet, 18 is a gap portion, and 19 is a bridge portion. (Part between the inner surface of the gap and the outer surface of the rotor core), 2
Numeral 0 denotes a stopper, 21 denotes a compressor, 35 denotes a driving means, and 41A and 41B denote gaps.

Claims (8)

[Claims] 1. A stator comprising a stator core and a plurality of phases of stator windings mounted thereon, and a substantially plate-shaped permanent magnet mounted inside the rotor core in a form orthogonal to the radial direction. And a rotor rotatably disposed inside a stator core of the stator, wherein each end portion of the permanent magnet in the rotor core has a rotor core outer surface. A gap is formed that extends to the vicinity, and the thickness dimension of a portion between the inner surface of the gap and the outer surface of the rotor core is set to decrease from the end of the permanent magnet toward the adjacent permanent magnet. A permanent magnet type motor characterized in that: 2. The permanent magnet type according to claim 1, wherein the degree of reduction in the thickness dimension of the portion between the inner surface of the air gap and the outer surface of the rotor core is reduced on the adjacent permanent magnet side. motor. 3. A stator constituted by mounting a plurality of phases of stator windings on a stator core, and a substantially plate-shaped permanent magnet mounted in a direction perpendicular to the radial direction inside the rotor core. And a rotor rotatably disposed inside a stator core of the stator, wherein each end portion of the permanent magnet in the rotor core has a rotor core outer surface. A gap is formed that extends close to the rotor core, and a dimension from the center of the rotor core to the outer surface of the rotor is set to be shorter from an end of the permanent magnet toward an intermediate portion between adjacent permanent magnets. Claim 1 characterized by the following:
A permanent magnet type motor as described. 4. A stator constituted by mounting a plurality of phases of stator windings on a stator core, and a substantially plate-shaped permanent magnet mounted in a direction perpendicular to the radial direction inside the rotor core. And a rotor rotatably disposed inside a stator core of the stator, wherein each end portion of the permanent magnet in the rotor core has a rotor core outer surface. Forming a gap extending close to the end of the permanent magnet pole in the gap at one end of the permanent magnet, and an end of the gap at the other end on the center of the permanent magnet pole; Wherein the opening angle based on the center of the rotor core is set to be an electrical angle of 90 to less than 130 degrees. 5. The permanent magnet type motor according to claim 1, wherein the permanent magnet is made of a rare earth magnet. 6. The permanent magnet type motor according to claim 1, further comprising a driving unit for supplying a sinusoidal current to the plural-phase stator windings. 7. The permanent magnet type motor according to claim 1, wherein the gap portion is provided with a slip stopper that comes into contact with an end of the permanent magnet. 8. The permanent magnet according to claim 1, wherein the suction means supplies a gasket to the compression space, the compression means compresses the gasket supplied into the compression space, and the compression means is driven. What is claimed is: 1. A compressor comprising: a shape motor; and discharge means for discharging a compressed gasket.