JP2002118994A - Motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a rotor construction capable of reducing the cogging torque, without skewing the rotor, in a synchronous motor which has a construction with a permanent magnet buried in the rotor. SOLUTION: The cogging torque is reduced by arranging the angles that the positions on the surface of a rotor where the magnetic poles 5, 6, 7, and 8 of permanent magnets arranged within the rotor switch from N to S or from N to S formed from the center of the rotor, so as be arranged at each position with unequal separation for each permanent magnet.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a synchronous rotating machine constituted by using permanent magnets.

[0002]

2. Description of the Related Art A rotor having a plurality of permanent magnets embedded therein,
A stator having a plurality of slots arranged at equal intervals in the circumferential direction, and a coil portion having a winding wound on the slot,
In an electric motor that is driven to rotate by magnet torque and reluctance torque, during its operation, that is, when the rotor rotates, torque pulsation corresponding to the number of slots arranged in the stator, so-called cogging torque, is generated. When the magnetic flux generated by the permanent magnets disposed inside the rotor forms a closed magnetic path through the slots arranged on the stator side, the cogging torque causes the electromagnetic force at an arbitrary rotation angle between the stator and the rotor. This is a value obtained by summing the suction force in the rotation direction. Therefore, a close relationship is established between the relative position of the rotor and the stator and the cogging torque.

[0003] The magnitude and generation cycle of the cogging torque are generally determined depending on the number of magnetic poles and the number of slots of the permanent magnet. Slots arranged at equal intervals on the stator side are equally spaced repetitions of a slot part having a small reluctance and a slot opening having a very large reluctance in terms of a magnetic circuit.
During the operation, that is, when the rotor rotates, the magnetic poles of the permanent magnets disposed inside the rotor pass at regular intervals through the slot portion having a small reluctance and the slot opening having a very large reluctance. At this time, since the magnetic flux of the permanent magnet always tries to go to the slot side where the magnetic resistance is small, when the magnetic pole of the permanent magnet passes through one slot pitch which is the angle formed by adjacent slots arranged on the stator side. Then, the electromagnetic attraction force is switched in the rotation direction or the anti-rotation direction of the rotor, and as a result, cogging torque is generated with a period proportional to the number of magnetic poles and the number of slots of the permanent magnet.

As an effective means for reducing the cogging torque, there is known a so-called skew method in which the rotors are arranged at equal intervals in the circumferential direction which is the rotation direction of the rotor when the rotors are laminated in the axial direction. This is because the relative position when the magnetic pole of the permanent magnet disposed on the rotor passes through the slot on the stator side is shifted in the circumferential direction, and the maximum position of the cogging torque generated by each layer is shifted in the circumferential direction. This is a technique for reducing cogging torque. Although this method is very effective in reducing cogging torque, in the case of a synchronous motor that forms a rotor by embedding a permanent magnet inside the rotor, the structure of the permanent magnet is three-dimensionally curved. It is very complicated and difficult to manufacture. Therefore, a so-called multi-stage skew method in which the skew is divided into two or more finite pieces in the axial direction is also useful. Leakage flux that forms a path is generated, and as a result, the flux linkage of the winding by the permanent magnet penetrating from the rotor side to the stator side decreases, and even if the same current flows, the same torque can be obtained. become unable.

[0005]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a rotor having a plurality of permanent magnets embedded therein, a stator having a plurality of slots arranged at equal intervals in a circumferential direction, and applying a winding to the slots. An object of the present invention is to reduce, without skew, the magnitude of cogging torque generated at the time of operation of an electric motor that includes a coil portion and that is driven to rotate by magnet torque and reluctance torque.

Further, by formulating the optimum rotor structure for reducing the cogging torque by a relational expression, a rotor structure capable of sufficiently obtaining an effect even with an arbitrary number of slots and magnetic poles is provided. To provide.

[0007]

SUMMARY OF THE INVENTION The rotor structure of the present invention comprises:
A rotor having a plurality of permanent magnet-embedded slits, a permanent magnet embedded in the slit, a stator having a plurality of slots, and a coil portion having a winding wound in the slot, and a magnet torque and a reluctance torque In the electric motor driven to rotate, the slit pitch angle of the permanent magnet embedded slit has a plurality of slit pitch angles in the rotor, so that the cogging torque is reduced without skewing the rotor in the axial direction. It can be reduced. As shown in FIG. 1, the angle θ _m formed by the position of the rotor surface at which the magnetic pole of the permanent magnet disposed inside the rotor switches from N to S or from N to S is formed from the center of the rotor.
Are arranged at unequal intervals by permanent magnets arranged at respective positions to reduce cogging torque.

At this time, based on the following (Equation 1), the position of the rotor surface where the magnetic pole of the permanent magnet switches from N to S or from N to S forms an angle θ _m formed by the center of the rotor.
, The cogging torque can be further reduced.

[0009]

(Equation 1)

Here, n is an arbitrary natural number, d1 is an angle formed by one slot on the stator side, d2 is a minimum angle formed by left and right slots sandwiching one slot on the stator side,
P indicates the number of poles of the rotor, and k indicates a natural number from 1 to P.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention provides a rotor having a plurality of permanent magnet embedded slits, a permanent magnet embedded in the slits, a stator having a plurality of slots, and a winding applied to the slots. A permanent magnet embedded slit having a plurality of slit pitch angles in the rotor, wherein the slit pitch angle of the permanent magnet embedded slit is a plurality of slit pitch angles in the rotor.

The cogging torque is highest when the magnetic flux on the rotor surface when the magnetic pole of the permanent magnet embedded in the rotor switches from N to S or from N to S passes between the slot and the slot opening. It occurs greatly. this is,
At the rotor surface where the magnetic pole of the permanent magnet embedded inside the rotor switches from N to S or from N to S when the rotor rotates, the magnetic flux on the rotor surface prevents the magnetic circuit from closing inside the rotor. There is a large amount of magnetic flux inclined in the circumferential direction due to the influence of the bridge portion, which is a magnetic path barrier provided for the slot, and the magnetic flux has a slot with a very high magnetic resistance against a slot with a very high magnetic resistance. This is because the circumferential direction component of the magnetic attraction force becomes extremely large when passing through the portion.

Here, the position of the rotor surface at which the magnetic pole of the permanent magnet switches from N to S or from N to S with respect to one permanent magnet is one position each on the left and right as viewed from the center position of the magnetic pole of the permanent magnet. Exist one by one. If the angle of the rotor surface at which the magnetic pole of the permanent magnet switches from N to S or from N to S is formed from the center of the rotor as θ _m , the angle θ _m is disposed inside the rotor. By arranging the permanent magnets at irregular intervals, the permanent magnets arranged inside the rotor pass between the slot and the slot opening at different periods, and the magnetic poles of the permanent magnets are N from the S, or the position of the rotor surface is switched from N to S it is possible to reduce the maximum value in the case as compared to the cogging torque equally spaced angles theta _m which forms the center of the rotor.

Further, the relationship between the slit pitch angle θ _m and the slot pitch d is as follows: θ _m [k] = nd ± d / 2P (P + k−1) {n: natural number, P: pole number} Thus, the cogging torque is minimized.

[0015] The present invention also provides a rotor having a plurality of slits for embedding permanent magnets, a permanent magnet embedded in the slits, a stator having a plurality of slots, and a coil unit having a winding wound in the slots. A motor that is driven to rotate by a magnet torque and a reluctance torque, wherein a slit interval width between adjacent permanent magnet embedded slits is a motor having a plurality of slit interval widths in the rotor. Is also good.

Also, the present invention provides a rotor having a plurality of permanent magnet embedded slits, a permanent magnet embedded in the slit, a stator having a plurality of slots arranged at equal intervals in a circumferential direction, and And a rotating portion driven by magnet torque and reluctance torque, wherein a pitch angle between adjacent slits formed by adjacent permanent magnet embedded slits is plural in the rotor. The motor may be provided with a pitch angle between the slits.

Further, since the plurality of permanent magnets embedded in the rotor are all of the same size, the magnetic flux generated by the magnet torque is the same, and stable rotation can be performed.

Further, by filling a resin into a flux barrier portion formed between the permanent magnet embedded in the slit and the end face of the slit, the permanent magnet can be prevented from moving even when rotated.

Further, by providing a projection on the slit end surface so that the permanent magnet embedded in the slit does not move in the slit, the permanent magnet can be prevented from moving even when rotated.

Further, the slit in which the permanent magnet is embedded
By making the width of the part holding the permanent magnet thick and the width of the other parts narrow, it is possible to prevent the permanent magnet from moving even when rotated with a simple configuration.

Further, a motor in which a coil portion is formed by concentrated winding is effective because cogging torque is easily generated.

The present invention may be applied to a compressor equipped with a motor.

[0023]

(Embodiment 1) Next, an embodiment of the present invention will be described. FIG. 1 includes a rotor having a plurality of permanent magnets embedded therein, a stator having a plurality of slots arranged at equal intervals in a circumferential direction, and a coil portion having windings formed in the slots, and a magnet torque and a reluctance torque. 1 shows an electric motor driven to rotate. As shown in the figure, the magnetic pole of the permanent magnet embedded inside the rotor changes from N to S or from N to S
The angle formed by the position of the rotor surface that switches to the center of the rotor is different for each permanent magnet.

When the rotor of the electric motor having the structure shown in this figure rotates, the position of the rotor surface at which the magnetic pole of the permanent magnet embedded inside the rotor switches from N to S or from N to S is fixed. The period that passes between the slot and the slot opening arranged on the daughter side passes through the permanent magnet 1, the permanent magnet 2, the permanent magnet 3, and the permanent magnet 4 at different timings.

FIG. 2 shows the relative position of the position of the rotor surface where the magnetic poles of the permanent magnets disposed inside each rotor are switched from N to S or from N to S with the slots arranged on the stator side. FIG. FIG. 2 (a)
(B) As shown in (c) and (d), the angles formed by the positions of the rotor surface where the magnetic poles of the permanent magnets disposed inside the rotor switch from N to S or from N to S are different from each other. It can be seen that when the rotor having this configuration rotates, a time delay occurs in the order in which the switching portions of the respective magnetic poles pass between the slot portion arranged on the stator side and the slot opening. It can be seen from this effect that the cogging torque can be reduced in an electric motor having a rotor in which a plurality of permanent magnets are arranged inside the rotor, as compared with a conventional case where permanent magnets are arranged at regular intervals.

Further, for one of the magnetic poles of the permanent magnet, the angle θ _m formed by the position of the rotor surface at which switching from N to S or from N to S is substantially equal to the angle d 1 formed by one slot on the stator side, The angle between the remaining permanent magnets and the difference between the minimum angle d2 formed by the left and right slots sandwiching one slot on the stator side and the angle d1 formed by one slot on the stator side were equally divided by the number of poles P + 1 of the rotor. By giving an angle approximately equal to the value, the position of the rotor surface where the magnetic pole of each permanent magnet switches from N to S or from N to S is regulated with respect to the slots arranged on the opposed stator side. In this case, the maximum position of the cogging torque generated by each permanent magnet can be shifted at equal intervals in the circumferential direction. Can be minimized.

(Embodiment 2) Next, another embodiment of the present invention will be described. FIG. 3 shows a rotor in which a plurality of permanent magnets are embedded, a stator having a plurality of slots arranged at equal intervals in the circumferential direction, and a coil section in which the slots are wound with a magnet, and magnet torque and reluctance torque. 1 shows an electric motor driven to rotate. Further, the length and shape of the permanent magnets arranged inside the rotor are all the same, and both ends of each permanent magnet are provided to prevent magnetic flux on the rotor surface from closing the magnetic circuit inside the rotor. A flux barrier portion, which is a magnetic path barrier, is provided.

As shown in the figure, the permanent magnet and the flux barrier portion embedded in the rotor
The angle between the center of the rotor and the position of the rotor surface that switches from N to S or from N to S is different for each permanent magnet and flux barrier.

When the rotor of the electric motor having the structure shown in this figure rotates, the position of the rotor surface at which the magnetic pole of the permanent magnet embedded in the rotor switches from N to S or from N to S is fixed. The period of passing between the slot and the slot opening arranged on the daughter side passes at different timings for the permanent magnet 11, the permanent magnet 12, the permanent magnet 13, and the permanent magnet 14, and in this case, The maximum position of the cogging torque generated by each permanent magnet can be shifted in the circumferential direction, and the cogging torque as a whole can be reduced.

Further, by employing the structure shown in this figure, it is possible to reduce the cogging torque while keeping the length and shape of each permanent magnet the same, and to manufacture a rotor of a motor having this structure. Therefore, the conventional parts can be used as they are, and the cost can be reduced.

Further, the permanent magnet and the flux barrier portion embedded in the rotor shown in this figure have a rotor surface where the respective magnetic poles switch from N to S or from N to S, which is formed from the center of the rotor. By allocating the angles in the same manner as in the first embodiment, it is possible to shift the maximum position of the cogging torque generated by each permanent magnet at equal intervals in the circumferential direction, thereby minimizing the overall cogging torque. It is possible.

[0032]

According to the rotor structure of the synchronous motor according to the first, third and fourth aspects of the present invention, the rotor in which the magnetic pole of the permanent magnet disposed inside the rotor is switched from N to S or from N to S. By arranging the angles formed by the surface positions at unequal intervals, it is possible to reduce the cogging torque without skewing the rotor.

Further, the invention according to claim 2 is characterized in that one of the magnetic poles of the permanent magnet is changed from N to S or from N to S
The angle formed by the position of the rotor surface that switches to is approximately equal to the angle d1 formed by one slot on the stator side, and the angle formed by the remaining permanent magnets is the minimum formed by the left and right slots sandwiching one slot on the stator side The difference between the angle d2 and the angle d1 formed by one slot on the stator side is represented by the number of poles P of the rotor.
By giving the values equally divided by +1 respectively, the cogging torque can be further reduced.

According to the fifth aspect of the present invention, the magnetic flux generated by the magnet torque is the same, and stable rotational driving is possible.

According to the sixth aspect of the present invention, the permanent magnet can be fixed by filling the resin into the flux barrier portion.

According to the seventh aspect of the present invention, a permanent magnet can be fixed by providing a projection on the end face of the slit.

According to the present invention, the permanent magnet can be fixed by changing the width of the slit.

According to the ninth aspect of the present invention, cogging torque, which is a major problem of a concentrated winding motor, can be reduced.

[Brief description of the drawings]

FIG. 1 is a sectional view of a synchronous motor showing a rotor structure according to a first embodiment of the present invention.

FIGS. 2A, 2B, 2C, and 2D are explanatory diagrams illustrating a configuration of a first embodiment;

FIG. 3 is a sectional view of a synchronous motor showing a rotor structure according to a second embodiment of the present invention.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 stator core 2 slot 3 winding 4 rotor core 5 permanent magnet 1 6 permanent magnet 2 7 permanent magnet 3 8 permanent magnet 4 9 rotating shaft 11 permanent magnet 11 12 permanent magnet 12 13 permanent magnet 13 14 permanent magnet 14 15 flux barrier

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H02K 19/10 H02K 19/10 A 21/14 21/14 MF Term (Reference) 5H002 AA04 AA05 AB06 AB07 AC06 AC07 AE08 5H619 AA01 AA03 BB01 BB06 BB24 PP02 PP04 PP08 5H621 AA02 GA01 GA15 GA16 HH01 JK02 JK05 5H622 AA02 AA03 CA02 CA07 CA13 CB05 CB06 PP11 PP20 QB03

Claims (10)

[Claims] A rotor having a plurality of permanent magnet embedded slits, a permanent magnet embedded in the slits, a stator having a plurality of slots, and a coil unit having a winding wound in the slots; An electric motor driven to rotate by magnet torque and reluctance torque, wherein the slit pitch angle of the permanent magnet embedded slit has a plurality of slit pitch angles in the rotor. 2. The relationship between the slit pitch angle θ _m and the slot pitch d is as follows: θ _m [k] = nd ± d / 2P (P + k−1) {n: natural number, P: number of poles}. An electric motor as described. 3. A rotor having a plurality of permanent magnet embedded slits, a permanent magnet embedded in the slits, a stator having a plurality of slots, and a coil part having a winding wound in the slots, An electric motor which is driven to rotate by magnet torque and reluctance torque, wherein a slit interval between adjacent permanent magnet embedded slits has a plurality of slit intervals in the rotor. 4. A rotor having a plurality of permanent magnet embedded slits, a permanent magnet embedded in the slits, a stator having a plurality of slots arranged at equal intervals in a circumferential direction, and a winding wound in the slots. Provided with a coil portion, and a rotating angle driven by magnet torque and reluctance torque, wherein a pitch angle between adjacent slits formed by the adjacent permanent magnet embedded slits is a plurality of pitches between slits in the rotor. An electric motor with an angle. 5. A plurality of permanent magnets embedded in a rotor,
Claims 1 to 3 each having a permanent magnet of the same size
The electric motor according to any one of the above items 4. 6. The electric motor according to claim 1, wherein a resin is filled in a flux barrier portion formed between a permanent magnet embedded in the slit and an end face of the slit. 7. The electric motor according to claim 1, wherein a projection is provided on an end surface of the slit so that a permanent magnet embedded in the slit does not move in the slit. 8. The electric motor according to claim 1, wherein the slit in which the permanent magnet is embedded has a thicker portion for holding the permanent magnet and a narrower width for other portions. 9. The electric motor according to claim 1, wherein the coil portion is formed by concentrated winding. 10. A compressor equipped with the electric motor according to claim 1.