JPH05236688A - Permanent magnet type motor - Google Patents

Abstract

PURPOSE:To improve the driving efficiency of a motor by-providing a magnetic projection at the section corresponding to the current application section (electric angle) of a stator coil. CONSTITUTION:In a rotor iron core 2', in case that the current application section for one phase of a stator coil is 120 deg., a circular projection 6a is made in the section equivalent to 30-150 deg. in terms of electric angle and the section of 60 deg. in center angle, equivalent to 15-75 deg. in terms of electric angle, and also as regards permanent magnets 7, 8, and 9 for magnetic fields, circular projections 7a, 8a, and 9a are made, respectively, in the section equivalent to 30-150 deg. in terms of electric angle for one pole and the section of 60 deg. in center angle, equivalent to 15-75 deg. in terms of mechanical angle, on the peripheral side in each radial direction. Hereby, the space magnetic flux density at these projections 6a, 7a, 8a, and 9a can be elevated. Accordingly, the driving torque of a motor itself can be increased. Hereby the driving efficiency of the motor improves.

Description

Detailed Description of the Invention

 [Object of the Invention]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a permanent magnet type motor used as a motor for driving a compressor of a refrigerator or an air conditioner.

[0002]

2. Description of the Related Art In recent years, a permanent magnet type motor whose rotation speed is easily controlled has been generally used as a motor for driving a compressor of a refrigerator or an air conditioner. Hereinafter, with reference to FIGS. 7 to 9, the presently commonly used permanent magnet type motor will be described.

Reference numeral 21 in FIG. 7 denotes a stator, and this stator 2
In Fig. 1, for example, twelve semi-closed slots 21a having openings 21b on the inner peripheral surface side are formed at equal intervals in a circumferential shape, and these semi-closed slots 21a are formed in the figure. 6 sets of stator coils 23u, 23v, 23
W and 24u, 24v, and 24w are wound and stored.
The six sets of stator coils 23u to 24w are configured to be supplied with a three-phase linear excitation current from a DC power source (not shown).
U phase for 4u, V phase for stator coils 23v and 24w,
The W phase corresponds to each of the stator coils 23w and 24w.

Reference numeral 22 denotes a rotor, which has a rotary shaft 25 at the central position as shown in FIG. And the rotary shaft 25
Around the field are permanent magnets 26, 27, 28 and 29 for field magnets.
Are arranged in a substantially square shape so as to surround the rotary shaft 25. Of the field permanent magnets 26 to 29, the field permanent magnets 26 and 28 that face each other are magnetized to the N pole, and the other field permanent magnets 27 and 2 that face each other.
9 is magnetized to the S pole. The salient pole portions 26a, 27a, 28 are provided on the outer sides of the field permanent magnets 26 to 29 in the radial direction.
a and 29a are arranged in an orthogonal state.
The salient pole portions 26a and 28a are magnetized to the N pole, and the salient pole portions 27a and 29a are magnetized to the S pole in correspondence with the field permanent magnets 26 to 29.

In the permanent magnet type motor having the above-mentioned structure, a motor driving device (not shown) outputs two phases to U-phase, V-phase and W-phase corresponding to each stator coil 23u to 24w of the stator 21. 120 electrical phase in the prescribed order phase by phase
The rotor 22 is rotationally driven by a magnetic attractive force and a repulsive force generated by energizing the rotor 22.

By the way, in such a conventional permanent magnet motor, the magnetic flux distribution generated in the gap between the stator 21 and the salient pole portions 26a to 29a of the rotor 22 is as shown in FIG. As shown in FIG. 9, it has a substantially trapezoidal wave shape with respect to the electrical angle. On the other hand, a magnetic flux is generated in the stator coils 23u to 24w by passing a direct-current exciting current at an electrical angle of 120 degrees, and as described above, the magnetic flux of the field permanent magnets 26 to 29 is generated. Drive torque is generated in the rotor 22 due to the interaction of (1) and (2) to start rotational driving.

Here, since the torque generated for one phase of the motor is expressed by the following equation (1), T = K × B × I (1) T: drive torque of the motor K: number of turns of the stator coil, etc. B: Magnetic flux density of air gap I: Winding current Motor drive torque generated in each phase of U-phase, V-phase, and W-phase is a portion where current flows in stator coils 23u to 24w. Is configured to occur only in.

[0008]

However, in the structure of the rotor 22 of the conventional permanent magnet type motor as described above, for example, when a method of energizing at an electrical angle of 120 degrees is adopted,
Among the magnetic fluxes generated by the field permanent magnets 26 to 29 as one pole, a driving torque of an electrical angle of approximately 120 degrees acts, so that the electrical angle shown by the shaded portion in FIG. 0 degree to 30 degrees and 150 degrees to 1
The magnetic flux generated in the portion corresponding to 80 degrees hardly acts as the driving torque of the motor. Therefore, the magnetic flux generated from the field permanent magnets 26 to 29 cannot be effectively used, and there is a problem that the driving torque of the motor is reduced.

The above-mentioned problem is not related to the energization section, and the conventional motor has an electrical angle of 18 degrees.
When the angle is less than 0 degree, the magnetic flux for one pole is not effectively used for the driving torque of the motor. Therefore, there is a problem that there is a limit in downsizing the motor and improving the driving efficiency. Was there. [Constitution of Invention]

[0010]

SUMMARY OF THE INVENTION In order to solve the above-mentioned technical problems, the present invention provides a stator in which a plurality of phases of stator coils are wound around a substantially annular stator core, and the stator. The rotor core arranged concentrically with the inner peripheral surface of the child and having a slight air gap part is provided with N permanent magnetic field magnets continuously and alternately.
A rotor arranged in a substantially circular shape so as to form a pole and an S pole, and a current of less than 180 degrees is sequentially applied to the stator coil in terms of an electrical angle in a one-phase current-carrying section. In the permanent magnet type motor for rotationally driving the rotor, a magnetic protrusion portion is formed in a portion facing the void portion of the rotor corresponding to an energization section in which a current is applied to the stator coil. And a permanent magnet type motor.

[0011]

The permanent magnet type motor of the present invention has the above structure.
The air gap magnetic flux distribution in the air gap existing between the stator and the rotor is the conduction section (electrical angle) in which the current flows through the stator coil.
Since the magnetic protrusion portion is formed in the portion corresponding to, it is possible to increase the air gap magnetic flux density of the air gap in this portion, and thus it is possible to increase the driving torque of the motor itself.

[0012]

EXAMPLE A three-phase quadrupole is described below as an example of the present invention.
The one-phase energization section applied to a permanent magnet type motor having an electrical angle of 120 degrees will be described with reference to FIGS. 1 to 5.

First, in the overall structure, reference numeral 1 in FIG. 1 denotes an annular disk-shaped stator, and this stator 1 is a stator core 1
'And six sets of stator coils 3u, 3v, 3w and 4u, 4
v, 4w. The stator core 1 ′ has a substantially annular shape, and a semi-closed slot 1 a having an opening 1 b is formed on the inner peripheral surface side of the stator core 1 ′, for example, 12
They are formed in a circular shape so that they are evenly spaced. Then, in the semi-closed slot 1a, as shown in the figure, six sets of stator coils 3u, 3v, 3w and 4u,
4v and 4w are wound around and housed in predetermined semi-closed slots 1a. Each of these stator coils 3u to 4w is configured to be supplied with a three-phase direct-current excitation current from a direct-current power supply 11 which will be described later. The stator coils 3u and 4u are provided with a U-phase and a stator coil 3v. , 4v are connected to the V phase, and stator coils 3w and 4w are connected to the W phase, respectively.

Further, the rotor 2 is arranged on the inner peripheral portion of the concentric circle of the stator 1 so that a small gap portion 10 is evenly interposed between the inner peripheral surface of the stator 1. This rotor 2
As also shown in FIG. 2, for example, a rotor core 2 ′ formed by laminating a large number of substantially annular thin silicon steel plates,
The rotor core 2'is constituted by a rotary shaft 5 fitted in a central position and four permanent magnets 6, 7, 8 and 9 made of ferrite, for example. The field permanent magnets 6 to 9 are arranged and fixed so as to surround the rotating shaft 5 at substantially orthogonal positions and at the center position. Of these four field permanent magnets 6 to 9, a pair of field permanent magnets 6 and 8 arranged at positions facing each other are magnetized to, for example, N poles,
The other pair of field permanent magnets 7 and 9 is conversely S
It is magnetized to the pole. The rotor core 2 sandwiched between the surface of the permanent magnet 6 for field magnetism on the outer peripheral side in the radial direction and the void portion 10.
In the part ', when the energizing section for one phase of the stator coil is 120 degrees as described above, the electrical angle is 30 degrees to 1 degree.
The part corresponding to 50 degrees, 15 degrees to 75 degrees in terms of mechanical angle
A circular arc-shaped protrusion 6a is formed in a portion having a central angle of 60 degrees, which corresponds to a degree. As for the permanent magnets 7, 8 and 9 for the field magnets, on the outer peripheral side in the radial direction, a portion corresponding to an electrical angle of 30 degrees to 150 degrees for one pole, and a mechanical angle of 15 degrees, as in the protruding portion 6a. Arc-shaped projections 7a, 8a and 9 at a central angle of 60 degrees corresponding to degrees to 75 degrees
a are formed respectively. That is, the mechanical angle is 75 to 105 degrees, 165 to 195 degrees, and 255 to 2 degrees.
It has a configuration in which a notch is provided in a portion corresponding to 85 degrees, 345 degrees to 15 degrees. When the stator coils 3u to 4w are energized, these projecting portions 6a to 9a are at electrical angle positions corresponding to the energizing angle for one phase, that is, 120 electrical angles.
It is provided at a position corresponding to the degree.

Next, the electrical construction of an inverter power source, which is widely used for driving the permanent magnet type motor in this embodiment, will be described with reference to FIG. 1
Reference numeral 1 denotes a DC power supply, and a switching main circuit 12 is connected to the DC power supply 11. This switching main circuit 12 has six pairs of transistors 13 and free wheeling diodes 14, and these six pairs of transistors 13 and free wheeling diodes 14 are three-phase bridge-connected and have three-phase arm portions 12u. , 12v and 12w respectively have common connection points of the transistors 13 connected to output lines corresponding to the U-phase, V-phase and W-phase, respectively. The output lines corresponding to the U-phase, V-phase, and W-phase are connected to the respective terminals in which the stator coils 3u and 4u, the stator coils 3v and 4v, and the stator coils 3w and 4w are Y-connected. Reference numeral 15 is a control circuit for giving a control signal to the transistor 13 arranged in the switching main circuit 12,
Corresponding to stator coils for two adjacent phases of stator coils 3u and 4u, stator coils 3v and 4v, and stator coils 3w and 4w, the phases are shifted by 120 degrees in terms of electrical angle so as to energize. Is configured. The control circuit 15 is also connected to each output line corresponding to the U phase, the V phase, and the W phase, and the rotation of the rotor 2 causes the stator coil 3 to rotate.
The voltage induced in u to 4w is detected so that a motor drive signal corresponding to the rotational position of the rotor 2 can be obtained. FIG. 4 shows a sequence of energization for each phase, and a DC excitation current is energized for each phase at an electrical angle of 120 degrees.

The operation and action of this embodiment will be described below with reference to FIGS. 3 and 5. First, 6 provided in the switching main circuit 12 by the control circuit 15
A control signal is supplied to the two transistors 13. When the control signal is supplied to the transistor 13, the stator coil 3
The adjacent two-phase stator coils (for example, 3u, 4u and 3v, 4v) of u to 4w are energized, and hereinafter, the stator coils 3v, 4v and 3w, 4w, the stator coil 3
w, 4w and 3u, 4u, ...
It is energized 20 degrees. As described above, when the stator coils 3u to 4w are sequentially energized by 120 degrees, a rotating magnetic field by the stator 1 is generated, and the rotor 2 starts rotational driving by the magnetic attraction force and the repulsive force. At this time, the torque generated in the rotor 2 is increased as described below. That is, as in the configuration of FIG. 1, a portion corresponding to an electrical angle of 30 degrees to 150 degrees (a mechanical angle of 15 degrees).
Degree ~ 75 degrees, 105 degrees ~ 165 degrees, 195 degrees ~ 255
285 degrees to 345 degrees), the protruding portions 6a, 7a, 8
a, 9a (in other words, an electrical angle of 0 to 30 degrees and 150 to 180 degrees, that is, a mechanical angle of 75 to 105 degrees, 165 to 195 degrees, 255 to 285 degrees. Since a notch is formed in a portion corresponding to 345 degrees to 15 degrees), the magnetic flux distribution in the void portion 10 corresponding to the energization section to the stator coils 3u to 4w is magnetically protruding. Then, the magnetic flux density of this portion is strengthened, and the magnetic flux density of one pole increases as shown in FIG. 5 at the position corresponding to an electrical angle of one pole of 30 to 150 degrees. Therefore, the torque for one phase also increases. Therefore, the combined torque for the three phases also increases.

In the above embodiment, the case where the present invention is applied to a three-phase four-pole salient pole type brushless DC motor has been described, but the present invention is applied to this three-phase four-pole salient pole type brushless DC motor. The present invention is not limited to this, and it is of course possible to carry out various modifications as long as it is a permanent magnet type motor, and accordingly, the energization section can be changed to an electrical angle other than 120 degrees.

In the above embodiment, the field permanent magnets 6 to 9 used for the rotor 2 are described as magnets made of ferrite, and the rotor core 2'is formed by laminating a large number of thin silicon steel plates. However, it is not limited to these, and permanent magnets for field magnets such as Alnico and rare earths can be used. It is possible to do so.
Further, as the rotor position detection method, a method using a hall element or the like can be adopted.

In the above embodiment, the projection is provided at a portion corresponding to an electrical angle of 30 to 150 degrees. However, during the period when the current flows through the stator coil, the electrical angle is approximately 120 degrees. Although it is limited to the energization section α of, like the current (α + β) for one phase shown in FIG.
Strictly speaking, when the transistor 13 is off, the time β flowing in the free wheeling diode 14 is slightly longer, and the electric current continues to flow in the stator coil longer than 120 degrees in terms of electrical angle of energization. It is also possible to make the magnetic projection part a little larger.

[0020]

According to the permanent magnet type motor of the present invention, 1
Since a magnetic protrusion is formed on the rotor core portion facing the air gap corresponding to the current-carrying section in which current flows through the stator coil of the phase portion, the air gap magnetic flux at the point where this protrusion is formed is You will be strengthened. Then, the magnetic flux acting on the driving torque of the motor increases,
As a result, the generated drive torque is increased, and the excellent effect of improving the drive efficiency of the motor is achieved.

[Brief description of drawings]

FIG. 1 is a plan view of a permanent magnet type motor according to an embodiment.

FIG. 2 is an enlarged plan view of the rotor in FIG.

FIG. 3 is an electrical configuration diagram of a permanent magnet type motor.

FIG. 4 is a diagram showing an energization sequence diagram in one embodiment.

FIG. 5 is a diagram showing a magnetic flux distribution according to the present invention.

FIG. 6 is a diagram showing an amount of current flowing through one phase of a stator coil.

FIG. 7 is a plan view of a conventional permanent magnet motor.

8 is an enlarged plan view of the rotor in FIG.

FIG. 9 is a diagram showing a conventional magnetic flux distribution.

[Explanation of symbols]

 1 Stator 1'Stator iron core 2 Rotor 2'Rotor iron core 3u, 3v, 3w, 4u, 4v, 4w Stator coil 6,7,8,9 Permanent magnet 6a, 7a, 8a, 9a Protrusion Part 10 Void part

Claims (1)

[Claims] 1. A stator in which a stator coil having a plurality of phases is wound around a substantially annular stator iron core, and a rotation arranged concentrically with an inner peripheral surface of the stator and having a slight gap. And a rotor in which permanent magnets for field magnets are continuously arranged alternately on the child iron core in a substantially circumferential shape so as to have N poles and S poles. In the permanent magnet type motor for rotating and driving the rotor by sequentially applying a current of less than 180 degrees in electrical angle, the void portion of the rotor corresponding to an energization section in which a current is applied to the stator coil. A permanent magnet type motor characterized in that a magnetic projection portion is formed on a portion facing the.