JP3818338B2 - Permanent magnet motor - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an inner rotor type permanent magnet motor used in the compressor or the like, especially particularly, to a permanent magnet motor by effectively utilizing the reluctance torque of the motor achieve high efficiency.
[0002]
[Prior art]
An inner rotor configuration of this type of permanent magnet motor is formed by embedding a permanent magnet in a rotor core, and for example, those shown in FIGS. 5 and 6 have been proposed. As shown in FIG. 5, the rotor core 2 in the 24-slot stator core 1 has plate-like permanent magnets 3 arranged in the circumferential direction along the outer diameter corresponding to the number of poles (four poles) of the permanent magnet motor. A flux barrier 4 is formed between the adjacent permanent magnets 3. In addition, 5 is a center hole (hole for shafts).
[0003]
Here, assuming that the magnetic flux distribution in the gap portion between the permanent magnet 3 (between the teeth of the stator core 1 and the permanent magnet 3) is sinusoidal, the torque T of the permanent magnet motor is T = Pn {Φa · Ia · cos β-0.5 (Ld−Lq) · I ² · sin 2β}. T is the output torque, Φa is the armature flux linkage by the permanent magnets on the d and q coordinate axes, Ld and Lq are d and q axis inductances, Ia is the amplitude of the armature current on the d and q coordinate axes, and β is The advance angle of the armature current on the d and q coordinate axes from the q axis, Pn, is the number of pole pairs.
[0004]
In the above formula, the first term is the magnet torque generated by the permanent magnet 3, and the second two terms are the reluctance torque generated by the difference between the d-axis inductance and the q- axis inductance. For details, see T.W. IEEE Japan, Vol. See 117-D, No. 7, 1997. Moreover, although the rotor core 2 shown in FIG. 6 has the structure which has the permanent magnet 6 of a different shape from the permanent magnet 3 shown in FIG. 5, application of the said numerical formula is clear.
[0005]
[Problems to be solved by the invention]
However, in the permanent magnet motor, since the permanent magnets 3 and 6 exist in the q-axis magnetic path and the flux barrier 4 exists, the q-axis inductance Lq becomes small. As a result, the value of (Lq−Ld) in the above formula is small, that is, the reluctance torque is small and the total torque of the motor is small.
[0006]
Therefore, in order to increase the q-axis inductance Lq, it has been proposed to increase the number of permanent magnets per pole of the motor, that is, a multilayer embedded magnet structure. For details, please refer to the paper mentioned above. However, since the permanent magnets for each magnetic pole are multi-layered, there is a problem that the increase in the number of parts and the complexity of the manufacturing cannot be avoided.
[0007]
The present invention has been made in view of the above problems, and an object without increasing the number of magnets per one pole, it is possible to increase the inductance of the q-axis, it can be increased and thus the reluctance torque, An object of the present invention is to provide a permanent magnet type motor capable of improving the efficiency of the motor.
[0008]
[Means for Solving the Problems]
In order to achieve the above object, according to the present invention, there is provided a permanent magnet motor in which a magnet embedded field core (rotor core) is disposed in a stator core. 2 and the number of poles of the permanent magnet type motor is 2P poles (P; positive integer), the first core has a P with its core outer periphery magnetized to S poles. The first permanent magnets are embedded at equal intervals along the outer periphery of the core, and there are P first flux barrier holes at positions shifted by π / P in the rotational direction between the first permanent magnets. In the second core, P second permanent magnets each having a core outer peripheral side magnetized with an N pole are embedded along the outer periphery of the core at equal intervals, and between the second permanent magnets. At the position shifted by π / P in the rotational direction. P holes are formed for the first core, the first permanent magnet and the second hole are opposed to each other, and the second permanent magnet and the first hole are opposed to each other. The second core is coaxially connected .
[0009]
In this case, when forming the first core and the second core and superposed with the inner core, is included in the shape hole for the first hole is embedded second permanent magnet, said second hole Is preferably included in the shape hole for embedding the first permanent magnet.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to FIGS. In the permanent magnet type motor of the present invention, the inner rotor core is composed of a plurality of cores in which permanent magnets of the same polarity are embedded, and by forming a flux barrier hole in each core, the q-axis inductance increases, It is noted that the ratio of the magnet torque and the reluctance torque can be selected by the core.
[0011]
Therefore, for example, as shown in FIGS. 1 to 3, the rotor core (embedded magnet field core) 10 of this permanent magnet type motor has a permanent magnet 11 of the same polarity (for example, S pole) and a hole for a flux barrier. First core (iron core) 13 having two each 12, a second magnet (iron core) having two permanent magnets 14 having the same polarity (N pole) different from permanent magnet 11 and two holes 15 for flux barrier 16 The ratio of the first core 1 3 and the second core 1 6 1: better to 1. Reference numeral 17 denotes a core central hole (shaft hole).
[0012]
More specifically, the first core 13 is embedded in a position obtained by rotating the same-polarity (S-pole) permanent magnet 11 by π rotation, and each permanent magnet 11 is rotated by π / 2 (corresponding to the N-pole). Hole 12 is formed at a position where the The shape of the permanent magnet 11 and the hole 12 is preferably a reverse arc with respect to the outer diameter of the core, and the hole 12 is preferably smaller than the permanent magnet 11.
[0013]
Similarly, the second core 16 is embedded in a position obtained by rotating the same-polarity (N-pole) permanent magnet 14 by π rotation, and the hole 15 is formed at a position obtained by rotating each permanent magnet 14 by π / 2 . The shape of the permanent magnet 14 and the hole 15, the same Ku as the permanent magnet 11 and the hole 12, may be a reverse arc shape to the outer diameter of the core, also reducing the hole 15 from the permanent magnet 14.
[0014]
Then, as shown in FIGS. 1 and 4, the first and second cores 13 and 16 containing the permanent magnets 11 and 14 are overlapped in a form rotated by π / 2, and the d axis and the q axis coincide with each other. Let As a result, the permanent magnet 11 and the hole 15 are opposed to each other, the permanent magnet 14 and the hole 12 are opposed to each other, the hole 12 is included in the shape of the permanent magnet 14, and the hole 15 is included in the shape of the permanent magnet 11. Is done. That is, when the slits of the first and second cores 13 and 16 are formed, the smaller area slits are all included in the larger larger slit.
[0015]
The first and second cores 13 and 16 have two permanent magnets 11 and 14, respectively, but can be applied to a motor having 2P poles (P: positive integer). In this case, permanent magnets are embedded in P pieces of the same polarity (S pole or N pole) out of the 2P poles, and small holes for flux barriers are formed in the remaining P pieces of different poles. Then, the cores may be assembled by shifting each core by 2π / 2P (π / 2 for 4 poles). The winding of the stator core is applied in accordance with the 2P pole.
[0016]
The inductance will be described with reference to the rotor configuration diagram shown in FIG. The 24-slot stator core 18 is provided with three-phase (U-phase, V-phase and W-phase) armature windings, but the number of slots and the armature windings may be different. In the stator core 18, for example, the outer diameter side winding is the U phase, the inner diameter side winding is the W phase, and the intermediate winding is the V phase.
[0017]
The first and second cores 13 and 16 make it easier for the magnetic flux from the stator core 18 to enter the interior, so that the q-axis inductance Lq is increased, and the inductance difference (Lq−Ld) is increased, and the reluctance torque is increased. The size rather than made. That is, the first and second cores 13 and 16 have portions without permanent magnets.
[0018]
Since the hole 12 of the first core 13 is parallel to the permanent magnet 14 of the second core 16 and the hole 15 of the second core 13 is parallel to the permanent magnet 11 of the first core 13, the flux barrier The effect is exhibited effectively. In order to increase the difference in inductance (Lq−Ld), for example, the hole 12 may be moved closer to the outer diameter side of the rotor.
[0019]
Furthermore, if the permanent magnets 11 and 14 are enlarged and the holes 12 and 15 are enlarged , not only the magnet torque can be increased , but also the difference in inductance (Lq−Ld) can be further increased.
[0020]
In this way, the first and second cores 13 and 16 are embedded with permanent magnets 11 and 14 having the same polarity (S pole or N pole), respectively, and for the flux barrier relative to the permanent magnets 11 and 14. The holes 12 and 15 are provided so that only one permanent magnet 11 and 14 per pole is required, so that the cost is not increased, the q-axis inductance Lq can be increased, and the reluctance torque is increased. And a high-efficiency motor can be obtained.
[0021]
By the way, the rotor core 10 is formed by punching and laminating electromagnetic steel plates with a press and filling the permanent magnets 11 and 14 to magnetize them. During the pressing, the shape holes and holes 12 of the permanent magnets 11 and 14 are used. 15 and the center hole (shaft hole) 17. In this case, as described above, the slit of the permanent magnet 11 includes the slit of the hole 15 and the slit of the permanent magnet 15 includes the slit of the hole 12. There is no change, that is, the production efficiency is not lowered, and the cost is not increased. Further, fixed to housing the permanent magnets 11 and 14 described above (embedded), and Deb Rashiresu DC motor incorporating a magnetized rotor core, if used as an air conditioner compressor motor, to increase the cost Therefore, it is possible to improve the performance of the air conditioner (increasing operating efficiency, reducing vibration and noise).
[0022]
【The invention's effect】
As described above , according to the present invention, the inner rotor core is composed of the first and second cores, and the first core has the same 2P poles (P: positive integer) of the permanent magnet motor. Only P permanent magnets to be poles (S poles) are embedded, and P holes are formed at positions of poles (N poles) different from the poles, and the second core has the same pole (N poles). The number of magnets per pole is increased by embedding only the permanent magnet P and forming P holes at positions different from the pole (S pole) and overlapping the first and second cores. In other words, the first and second cores do not have permanent magnets with different polarities, so that the q-axis inductance can be increased and the reluctance torque can be increased. This is advantageous in that the efficiency of the motor can be improved.
[0023]
Further, since the holes of the first and second cores are included in the shape hole of the permanent magnet, in addition to the effect of claim 1, the hole is included in the shape of the permanent magnet. Therefore, there is an effect that the manufacturing cost of the motor is not increased.
[Brief description of the drawings]
FIG. 1 is a schematic longitudinal sectional view of an inner rotor of a permanent magnet motor according to an embodiment of the present invention.
FIG. 2 is a schematic partial cross-sectional view of the inner rotor shown in FIG.
FIG. 3 is a schematic partial cross-sectional view of the inner rotor shown in FIG. 1;
4 is a schematic plan view of a permanent magnet motor having an inner rotor shown in FIG. 1. FIG.
FIG. 5 is a schematic plan view of a conventional permanent magnet motor rotor.
FIG. 6 is a schematic plan view of a conventional permanent magnet motor rotor.
[Explanation of symbols]
10 Rotor core (embedded magnet field core)
11,14 Permanent magnet 12,15 hole (for flux barrier)
13 1st core 16 2nd core 17 Center hole (hole for shafts)
18 Stator core

Claims (2)

In a permanent magnet type motor in which an embedded magnet field core (rotor core) is disposed in a stator core ,
The rotor core includes first and second cores that are coaxially connected. The number of poles of the permanent magnet motor is 2P poles (P; a positive integer). The P first permanent magnets whose core outer peripheral side is magnetized to the S pole are embedded at equal intervals along the core outer periphery, and shifted by π / P in the rotational direction between the first permanent magnets. P first holes for the flux barrier are formed at the position,
In the second core, P second permanent magnets each having a core outer peripheral side magnetized with an N pole are embedded at equal intervals along the core outer periphery, and the rotation direction is between the second permanent magnets. P second holes for flux barrier are formed at positions shifted by π / P to
The first core and the second core are coaxially connected in a state where the first permanent magnet and the second hole are opposed to each other, and the second permanent magnet and the first hole are opposed to each other. permanent magnet motor, characterized in that there. The first hole is included in a shape hole for embedding the second permanent magnet, and the second hole is included in a shape hole for embedding the first permanent magnet. The permanent magnet motor according to claim 1 .

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