JPH10309050A - Compressor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the efficiency of a compressor and, at the same time, to reduce the vibration and noise of the compressor, by mounting as permanent- magnet motor having such a rotor structure that at least one or more layers of permanent magnets are protruded toward the center of a rotor by burying permanent magnets in a cylindrical rotor core in the radial direction at a rate of a plurality of layers per one magnetic pole. SOLUTION: A motor of a compressor is a four-pole motor composed of a rotor 1 and a stator 2. In the rotor 1, arcuate and protruding permanent magnets 4a and 4b are buried in a rotor core 3 formed by laminating magnetic steel sheets having high magnetic permeability upon another at a rate of two layers per one pole, and the magnetic paths 9 of the core 3 are provided between the two permanent magnets 4a and 4b. Since the magnetic paths 9 having a fixed width are provided between the magnets 4a and 4b, the g-axis inductance of the motor is increased and the motor effectively utilizes the reluctance torgue. Therefore, the efficiency of the motor is remarkably improved when the motor is operated at a low speed under a high-temperature condition. In addition, since grooves are provided on the inner peripheral sides of stator teeth, the vibration and noise of the motor can be reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a compressor applied to a hermetic refrigeration compressor mounted on a device such as a refrigerator, an air conditioner, or the like for cooling, freezing, or refrigeration.

[0002]

2. Description of the Related Art Conventionally, a permanent magnet motor having a structure in which a permanent magnet is embedded in a cylindrical rotor core made of a material having high magnetic permeability such as iron has been used for a compressor. The usage condition of the compressor motor is such that the motor rotates at a high speed at the start of operation, but the rotation speed is gradually reduced, and the motor is normally rotated at a low speed. For example, considering the cooling operation of an air conditioner, the air conditioner is operated at the maximum cooling capacity because the room is very hot at first. At this time,
The compressor motor rotates at the maximum operable speed. When the room temperature gradually decreases, the operation is performed so that the cooling capacity also decreases, and the rotation speed of the compressor motor gradually decreases. When the room temperature has dropped to a predetermined temperature, the air conditioner is operated with the minimum cooling capacity capable of maintaining the temperature. At this time, the compressor motor is driven at a low speed.

[0003] As described above, the usage condition of the compressor motor is such that the low-speed rotation time is very long. Therefore, if the motor efficiency during low-speed rotation is significantly improved, the power consumption of the compressor can be significantly reduced. The configuration of a conventional compressor motor will be described with reference to FIG. The compressor motor includes a rotor 21 and a stator 22. The rotor 21 has a rotor core 2 formed by laminating electromagnetic steel sheets of a high magnetic permeability material.
3, a permanent magnet 24 having a circular arc shape protruding toward the center of the rotor 21 is embedded therein. Stator 22
Has 24 stator teeth 26 on the stator core 25.
Are formed, and windings 28 are applied to 24 slots 27 between the stator teeth 26, 26,
The rotor 21 is rotated by a rotating magnetic field generated by applying a current to the winding 28.

In the above configuration, not only the magnet torque but also the reluctance torque can be used. FIG. 9 shows the torque of a permanent magnet motor having a permanent magnet disposed on the rotor surface. The torque is only magnet torque, and the torque becomes maximum when the current phase lead angle is 0 °. FIG. 10 shows that, as shown in FIG.
An arc-shaped permanent magnet 24 that is convex toward the center of the rotor 21
4 shows the torque of a permanent magnet motor embedded layer by layer. The total torque is the sum of the magnet torque and the reluctance torque. The reluctance torque has a current phase lead angle of 45.
°, the total torque is 3 when the current phase lead angle is 3
It becomes maximum near 0 °. Thus, when the same current is applied, in the case of a permanent magnet motor in which the rotor core is buried with a circular arc-shaped permanent magnet protruding toward the center of the rotor, one layer per magnetic pole, the current phase lead angle should be around 30 °. Thus, the reluctance torque can be effectively used in addition to the magnet torque. Therefore, the current is smaller under the same load than a permanent magnet motor in which permanent magnets are arranged on the rotor surface, so that copper loss is reduced and high efficiency can be realized. Further, as the number of rotations is lower, the ratio of copper loss to the loss is higher, so that the efficiency is further improved at low speed rotation.

[0005] Further, since the reluctance torque is not related to the thermal properties of the permanent magnet, even if the reluctance torque is operated in a high-temperature compressor, the deterioration of the properties due to heat is small as compared with normal temperature. Therefore, high efficiency can be realized by applying the permanent magnet motor having the configuration shown in FIG. 8 to the compressor, and the power consumption of the compressor can be reduced.

[0006]

However, the reluctance torque is determined by the ease of passing the magnetic flux of the magnetic path Pa1 (referred to as d-axis inductance) and the ease of passing the magnetic flux of the magnetic path Pa2 (referred to as q-axis inductance) in FIG. Although proportional to the difference, FIG.
In the configuration described above, the end face of the permanent magnet 24 is
To prevent the magnetic flux of the stator 22 from flowing into the rotor 21, the q-axis inductance is not much higher than the d-axis inductance.
There was a problem that reluctance torque could not be used effectively. Further, since such an embedded magnet type motor has a salient polarity in the rotor, the cogging torque increases, which causes vibration and noise to increase.
This is a serious problem for compressors of air conditioners and refrigerators that require clean sound.

SUMMARY OF THE INVENTION In view of the above-mentioned problems, the present invention provides a compressor motor having a rotor in which a permanent magnet is embedded, in which the q-axis inductance is increased, the efficiency is increased, and the cogging torque is reduced. To reduce vibration and noise.

[0008]

According to the compressor of the present invention, two or more permanent magnets are embedded in the cylindrical rotor core in the radial direction per magnetic pole, and at least one permanent magnet is protruded toward the center of the rotor. And a permanent magnet motor having a rotor structure.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention provides a rotor structure in which two or more permanent magnets are buried radially in a cylindrical rotor core per magnetic pole, and at least one permanent magnet is convex toward the center of the rotor. Is mounted on a compressor. As a result, the q-axis inductance is increased, the reluctance torque is effectively used, and the efficiency is improved. In particular, by effectively utilizing the reluctance torque, the efficiency is less reduced when operating in a high-temperature environment inside the compressor than at room temperature, and the efficiency is significantly improved particularly at low-speed operation.

The silicon content mass ratio is 2 to 10%.
The rotor core is formed by laminating electromagnetic steel sheets that increase iron resistance to reduce iron loss, or by laminating electromagnetic steel sheets that have a thickness of 0.4 mm or less to make eddy current difficult to flow. Or by forming the rotor core from an electromagnetic steel sheet having a reduced hysteresis loss by annealing at 740 to 800 ° C., or by appropriately combining them, a permanent magnet motor with a low iron loss and high efficiency can be obtained. And the power consumption of the compressor can be reduced.

On the other hand, by providing an auxiliary groove on the inner diameter side of each tooth of the stator core, an increase in cogging torque is suppressed even in an embedded magnet type rotor having high saliency and large cogging torque, thereby reducing vibration and noise. be able to.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below with reference to FIGS.
This will be described with reference to FIG. The motor in the compressor shown in FIG. 1 is a four-pole motor including a rotor 1 and a stator 2. The rotor 1 is constructed by embedding two permanent magnets 4a and 4b having a circular arc shape protruding toward the center of the rotor 1 in a rotor core 3 formed by laminating magnetic steel sheets of a high magnetic permeability material. The magnetic path 9 of the rotor core 3 is provided between the two layers of permanent magnets 4a and 4b. As described above, by using the arc-shaped permanent magnets 4a and 4b, the surface area can be increased and the amount of magnetic flux can be increased. Further, by providing a magnetic path 9 having a constant width between the permanent magnets 4a and 4b, the q-axis inductance is increased and the reluctance torque is effectively used. Here, the q-axis inductance is easy to pass along the magnetic path 9 of the magnetic flux flowing in the q-axis direction in FIG. The four sets of permanent magnets 4a and 4b are arranged so that the surface of the rotor 1 is alternately located with S poles and N poles.

The stator 2 has a configuration in which 24 stator teeth 6 are formed on a stator core 5, and windings 8 are applied to 24 slots 7 between the stator teeth 6, 6. The rotor 1 is configured to be rotated by a rotating magnetic field generated by flowing a current through the rotor 1. With the above configuration, under the same load, not only the magnet torque but also the reluctance torque is effectively used, so that the input is reduced and the efficiency is improved. Especially,
During low speed operation in which the copper loss accounts for a large proportion of the loss, the temperature dependence of the reluctance torque is low, so the effect of improving the efficiency when incorporating a compressor operated at high temperature is remarkable.

FIG. 2 shows a state in which the compressor motor of this embodiment shown in FIG. Reference numeral 11 denotes a motor unit, and 12 denotes a compression unit. FIG. 3 shows the case where the input at the same load at the time of high-speed rotation is the case where the magnet is arranged on the surface of the rotor core and the one-layer arc shape inside the rotor core when the room temperature (20 ° C.) and the high temperature (100 ° C.) 8 (a conventional product shown in FIG. 8) and a rotor core having two layers of arc-shaped permanent magnets embedded inside the rotor core (an embodiment of the present invention shown in FIG. 1). Shown.
The amount of permanent magnet used was the same for each motor. The product of the present invention has low input, that is, high efficiency, even at room temperature, but has a small decrease in efficiency even at high temperature, and has higher efficiency than the conventional product.

FIG. 4 shows an input at the same load during low-speed rotation at normal temperature (20 ° C.) and at a high temperature (100 ° C.) when a magnet is arranged on the surface of the rotor core and when a single layer is provided inside the rotor core. 8 (a conventional product shown in FIG. 8) and a rotor core in which two layers of a permanent magnet are embedded inside the rotor core (an embodiment of the present invention shown in FIG. 1). Are shown in comparison. The product of the present invention has a high efficiency even at room temperature, but has a small decrease in efficiency even at a high temperature, and has a higher efficiency than the conventional product.
Further, the efficiency improvement effect is more remarkable than at the time of high-speed rotation.

Therefore, by applying the compressor motor of this embodiment to the compressor, the operation efficiency can be greatly improved, and the power consumption of the compressor can be greatly reduced. Further, in the present embodiment, the magnetic flux increases to effectively use the reluctance torque, and the ratio of the iron loss to the loss increases. Therefore, the silicon-containing mass ratio of the electromagnetic steel sheet used for the rotor core 3 is set to 2 to 10%. Efficiency is improved by increasing the specific resistance and reducing the iron loss. By increasing the silicon content mass ratio to 2% or more, iron loss due to an increase in magnetic flux density from a permanent magnet motor having a permanent magnet disposed on the rotor surface using a conventional magnetic steel sheet having a silicon content mass ratio of less than 1%. The increase is suppressed, and iron loss equal to or less than that of the conventional permanent magnet motor is realized.
Note that, from the relationship between the strength and the saturation magnetic flux density, the silicon content mass ratio is 10% or less, and preferably, the iron loss takes a minimum value.
It is good to make it 5% or less. Furthermore, 740 ° C to 800 ° C
The iron core is annealed to reduce the hysteresis loss and achieve higher efficiency.

In particular, since the surface of the rotor is made of a material having a high magnetic permeability, the change in magnetic flux density on the surface of the rotor is large, and the eddy current loss is large. Further, in the compressor, PWM control is often used for speed control, and thus the magnetic flux density changes at a high cycle. Therefore, by reducing the thickness of the electromagnetic steel sheet to 0.4 mm or less, eddy current loss can be further reduced, and further improvement in efficiency can be realized. When these electromagnetic steel sheets are laminated to form an iron core, for example, compared to a case where an electromagnetic steel sheet having a sheet thickness of 0.5 mm and a silicon content mass ratio of 0.5% is used.
In a permanent magnet motor in which two layers of arc-shaped permanent magnets are embedded inside the rotor core, the efficiency has been improved by 2% or more.

FIG. 5 shows an example of the third embodiment of the present invention. In this figure, 31 is a stator tooth, and 32 is an auxiliary groove provided on the inner diameter side of the tooth 31. The width of the auxiliary groove is preferably substantially the same as the width of the slot open portion of the stator, and it is preferable to arrange one or more auxiliary teeth at equal intervals per tooth. The other reference numerals are the same as those in FIG. In this figure, by providing grooves on the inner diameter side of the stator teeth 31, permanent magnets 4a, 4
The amount of magnetic flux generated from b and entering the stator teeth 31 can reduce the amount of unbalance generated due to the positional relationship between the rotor 1 and the stator teeth 31. That is, cogging torque is reduced, and vibration and noise can be reduced.

FIG. 6 is a diagram showing the relationship between the rotation angle of the rotor and the cogging torque according to the embodiment of the present invention. This figure shows both the cogging torque of the motor without the auxiliary groove 31 and the cogging torque of the motor provided with the auxiliary groove. As is clear from this figure, it can be confirmed that the motor provided with the auxiliary groove 31 has about half the cogging torque of the motor without the auxiliary groove.

FIG. 7 shows another embodiment of the compressor motor according to the present invention. The same components as those in the embodiment of FIG. 1 are denoted by the same reference numerals, and description thereof will be omitted. The rotor 1 of the compressor motor according to this embodiment has six poles. The rotor 1 includes a permanent magnet 4c having a convex shape toward the center of the rotor and a plate-shaped permanent magnet 4d radially arranged and magnetized in the rotational direction. 3
To prevent the magnetic flux of the plate-like permanent magnet 4d from being short-circuited on the center side of the rotor 1 so that the adjacent plate-like permanent magnet 4d
A spacer 13 made of a space or a non-magnetic material is disposed on the center side of the rotor.

Also in this embodiment, since the iron magnetic path 9 is formed between the arc-shaped permanent magnet 4c and the plate-shaped permanent magnet 4d, which are convex toward the center of the rotor, the reluctance torque is effectively used. It has a shape that can be done. In addition, the operation and the operation are the same as those in the above-described embodiment, and the description is omitted.
The present invention is also applicable to a compressor motor having a rotor other than four or six poles, and the number of permanent magnet layers per magnetic pole may be three or more. However, when a ferrite magnet is used, a certain thickness of the permanent magnet is required due to the demagnetization resistance. Therefore, when the outer diameter of the rotor is 70 mm or less, the optimum number of permanent magnet layers per magnetic pole is two.

Further, as shown in the above embodiment, two poles of permanent magnets having a circular arc shape protruding toward the center of the rotor are arranged in the case of four poles, while the center of the rotor is arranged in the case of six poles. An arc-shaped permanent magnet and a plate-shaped permanent magnet that are convex on the side and are arranged in the radial direction and magnetized in the rotating direction are suitable for increasing the surface area of the permanent magnet and effectively using the magnetic flux of the permanent magnet. ing.

Further, in the above embodiment, the rotor core is illustrated as being integrally punched. However, the rotor core may be integrally formed by laser welding, aluminum die casting, or the like, and a permanent magnet may be embedded therein. .

[0024]

According to the compressor motor of the present invention, as is apparent from the above description, two or more permanent magnets are buried in the radial direction per magnetic pole, and at least one or more, preferably a plurality of permanent magnets are provided. With the rotor structure in which the permanent magnet is convex toward the center of the rotor, the q-axis inductance can be increased by the magnetic path formed between the layers of the permanent magnet, the reluctance torque can be used effectively, the efficiency can be improved, and the reluctance torque can be improved. Is effectively used, the efficiency is less reduced even when operating at a high temperature than at room temperature, and especially when the compressor is incorporated into a compressor and operated at a low speed, the efficiency can be significantly improved. At the same time, by combining the stator with a stator having a configuration in which auxiliary grooves are provided in the stator teeth, a cogging torque can be reduced, and a compressor with low vibration and noise can be realized.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a schematic configuration of an embodiment of a compressor motor according to the present invention.

FIG. 2 is a sectional view of a compressor incorporating the motor.

FIG. 3 is a graph showing the input under the same load during high-speed rotation in comparison with the product of the present invention and the conventional product.

FIG. 4 is a graph showing the input at the same load during low-speed rotation in comparison with the product of the present invention and the conventional product.

FIG. 5 is a sectional view showing a schematic configuration of another embodiment of the compressor motor of the present invention.

FIG. 6 is a graph showing the relationship between the rotational position of the rotor and the cogging torque.

FIG. 7 is a sectional view showing a schematic configuration of another embodiment of the compressor motor of the present invention.

FIG. 8 is a sectional view showing a schematic configuration of a conventional compressor motor.

FIG. 9 is a torque characteristic diagram of a permanent magnet motor having a permanent magnet disposed on a rotor surface.

FIG. 10 is a torque characteristic diagram of a conventional compressor motor.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Rotor 3 Rotor core 4a, 4b, 4c Arc-shaped permanent magnet 4d Plate-shaped permanent magnet

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Takeshi Morishige 1006 Kadoma Kadoma, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. 72) Inventor Hiroshi Murakami 1006 Kazuma Kadoma, Kadoma City, Osaka Prefecture Inside Matsushita Electric Industrial Co., Ltd. 1006 Kadoma, Kadoma City Matsushita Electric Industrial Co., Ltd.

Claims (6)

[Claims] 1. A permanent magnet motor having a rotor structure in which two or more permanent magnets are embedded in a cylindrical rotor core in a radial direction per magnetic pole, and at least one permanent magnet is convex toward the center of the rotor. A compressor characterized in that: 2. The compressor according to claim 1, further comprising a permanent magnet motor having a rotor structure in which a plurality of layers of permanent magnets are arc-shaped convex toward the center of the rotor. 3. The rotor core having a silicon content mass ratio of 2 to 2.
3. The compressor according to claim 1, further comprising a permanent magnet motor configured by laminating 10% of electromagnetic steel sheets. 4. The compressor according to claim 1, further comprising a permanent magnet motor having a rotor core formed by laminating electromagnetic steel sheets having a thickness of 0.4 mm or less. 5. The compressor according to claim 1, further comprising a permanent magnet motor having a rotor core made of an electromagnetic steel sheet annealed at 740 to 800 ° C. 6. The compressor according to claim 1, wherein a permanent magnet motor having an auxiliary groove is mounted on a portion of the stator core facing the rotor on the inner diameter side of each tooth.