JP2001211582A - Permanent magnet motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To materialize a high efficiency of a permanent magnet motor by reducing a loss due to eddy current and increasing a magnet torque combined with a reluctance torque. SOLUTION: A rotor 10 inside a stator generating a rotating field is constituted of a permanent magnet 11 of rectangular cross section embedded along each q-axis in the radial direction and a wide notch 12 forming a flux barrier on the peripheral side of the permanent magnet 11 near the q-axis in the d-axis direction. The permanent magnet 11 is disposed in the circumferential direction with an equalized space corresponding to the number of poles, making the long side of the rectangular section the pole and magnetizing the long side of permanent magnet with the same polarity with each adjacently facing magnet.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a permanent magnet electric motor which uses a magnet torque and a reluctance torque in a motor used for an air conditioner, an electric vehicle, etc., and more particularly, to an improvement in the efficiency by increasing the magnet torque. To a permanent magnet motor.

[0002]

2. Description of the Related Art For example, there is a permanent magnet motor having a structure shown in FIG. This permanent magnet motor has a rotor 2 in a 24-slot stator 1 for generating a rotating magnetic field, and the rotor 2 has a pole number (4
Poles) of permanent magnets (eg, ferrite magnets) 3
Embedded along the axis.

The permanent magnet 3 has a rectangular cross section, and its rectangular end is buried toward the outer periphery of the rotor 2 and the shaft 4, and its side surface is used as a magnetic pole.
Opposite side surfaces of the adjacent permanent magnets 3 have the same polarity. By using the rotor 2 in which the permanent magnets 3 are embedded, it is possible to generate a magnet torque as a rotational force.

Further, one of the magnetic fluxes from the stator 1, q
Since the path (magnetic path) of the magnetic flux from the axis to the other q-axis is secured and the path of the magnetic flux from one d-axis to the other d-axis is obstructed by the permanent magnet 3, the inductance of the d-axis and the q-axis The difference increases and reluctance torque is generated. Therefore, since the total torque including the magnet torque and the reluctance torque is improved, a highly efficient motor can be realized.

[0005]

In the permanent magnet electric motor, the permanent magnet 3 is made as large as possible in order to increase the magnet torque. Further, in order to reduce the leakage flux, the short side end of the rectangular section of the permanent magnet 3 is extended to the vicinity of the outer periphery of the rotor 2, and the interval between the short side end and the outer periphery of the rotor 2 is narrowed. .

However, when the permanent magnet 3 is close to the surface of the rotor 2, an eddy current is easily generated on the surface. In particular, when a magnet having high conductivity (especially a rare earth magnet) is used, the eddy current increases, and the loss of magnetic flux due to the eddy current increases. Further, since the magnetic flux generated by the permanent magnet 3 is distributed over the entire surface of the rotor 2, the magnetic flux that contributes to the generation of the magnet torque is not so large, that is, the magnetic flux is not used effectively.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has as its object to reduce eddy currents, to make the magnetic flux generated by the permanent magnets salient, to effectively utilize the magnetic flux, and to reduce the reluctance torque. It is an object of the present invention to provide a permanent magnet motor capable of improving the torque of a magnet without increasing the efficiency of the motor.

[0008]

In order to achieve the above object, the present invention provides a permanent magnet motor having a rotor inside a stator for generating a rotating magnetic field, wherein the rotor comprises:
A permanent magnet having a rectangular cross section in the radial direction is embedded along the q-axis, and a flux barrier wide in the d-axis direction is formed near the q-axis on the outer periphery of the permanent magnet at the end of the permanent magnet. Are arranged at equal intervals in the circumferential direction by the number of poles, and the longer side of the cross-section rectangle is a magnetic pole, and the opposite side of the longer side of the adjacent permanent magnet is magnetized to the same pole. It is characterized by:

According to the present invention, there is provided a permanent magnet motor having a rotor inside a stator for generating a rotating magnetic field.
The permanent magnet is embedded along the axis and forms a flux barrier wide in the d-axis direction near the q-axis of the outer periphery on one end side of the permanent magnet, and a permanent magnet adjacent at the other end of the permanent magnet Forming a flux barrier of a pair of holes extending in the direction of, the permanent magnets are arranged at equal intervals in the circumferential direction by the number of poles, and the longer side of the cross-section rectangle is a magnetic pole, and the adjacent permanent magnet is It is characterized in that the opposite sides of the long side of the magnet are magnetized to the same polarity.

The flux barrier formed in the vicinity of the q-axis is a notch in which the outer periphery is formed in a groove shape.
It is good to make the shape open in the d-axis direction by a side parallel to the end of the permanent magnet and having the same length or longer than the same end, and two sides which are acute to the q-axis. .
Thereby, when manufacturing the rotor, the core sheets obtained by punching out the electromagnetic steel sheets are laminated, but the cutouts can be formed when the core sheet is punched out, so that the cost is not increased.

The flux barrier formed in the vicinity of the q-axis is a hole, and the hole is formed at an acute angle with respect to the q-axis with a side parallel to the end of the permanent magnet and having the same length or a side longer than the end. The core sheet has a shape that is open in the d-axis direction by the two sides and an arc along the outer periphery of the rotor, and forms a rotor between the hole and the outer periphery of the rotor. It is good to be more than thickness. As a result, as in the case of the cutout portion, the cost does not increase, and the occurrence of burrs and the like when punching the core sheet is reduced, thereby improving the yield.

The distance between the tip of the pair of holes and the tip of the adjacent pair of holes is preferably equal to or greater than the thickness of the core sheet constituting the rotor. Accordingly, the occurrence of the above-mentioned burrs and the like is reduced, and furthermore, the leakage and short circuit of the magnetic flux of the permanent magnet can be further reduced, and the strength of the core itself is not affected.

Preferably, the rotor core is fixed through a rivet on the d-axis in a region between the permanent magnets, and the rivet is made of a magnetic material. In this case, by covering both ends of the core laminated with the core sheet and passing rivets, the permanent magnet embedded inside does not move or jump out, and not only can the reliability be improved,
Disturbance such as the flow of magnetic flux in the rotor is reduced.

The material of the permanent magnet is preferably a ferrite magnet or a rare earth magnet. Thereby, various adaptive motors can be obtained in consideration of cost, torque, and the like.

It is preferable that the above-mentioned rotor punches out an electromagnetic steel sheet by an automatic press, and at the same time, automatically laminates the steel sheets in a mold, and embeds the above-mentioned permanent magnet in a hole punched out by the automatic press.
Thereby, the rotor can be manufactured by the conventional manufacturing technique, and the manufacturing cost can be reduced.

[0016]

FIG. 1 is a block diagram showing an embodiment of the present invention.
This will be described in detail with reference to FIG. In the figure, the same parts as those in FIG.

In FIG. 1 and FIG. 2, a rotor 10 of a permanent magnet motor according to a first embodiment of the present invention includes a permanent magnet 11 having a rectangular cross section which is long in the radial direction and having the same number of poles (along the q axis). (Four poles) at regular intervals, and a groove-shaped notch (flux barrier) wide in the d-axis direction between the end (short side of the rectangular cross section) of the permanent magnet 11 and the outer periphery.
12 are formed. The permanent magnet 11 has a magnetic pole on the long side of the rectangular cross section, and has the same pole on the opposite surface of the adjacent permanent magnet 11, that is, the motor has four poles.

In this case, in order to form the notch 12,
If the length of the permanent magnet 11 in the q-axis direction is slightly shortened, the magnet torque becomes smaller than before, but the width of the permanent magnet 11 (the dimension on the short side of the rectangular cross section) is increased accordingly. In other words, it is preferable to use the magnet in the same amount as the conventional example. If a rare earth magnet is used as the material of the permanent magnet 11 instead of the ferrite magnet, the permanent magnet 11
, The magnet torque can be made larger than in the conventional example.

The notch 12 has a side parallel to the end of the permanent magnet 11 and two sides symmetrical to the q-axis extending from both corners of the end to the edge of the outer circumferential circle of the rotor 10. . In other words, the trapezoid has an upper side and both hypotenuses, and the upper side has the same length as the end of the permanent magnet 11, and the hypotenuses are acute angles to the q axis.

The permanent magnet motor adopts a 120-degree energization method, and the central angle α of an arc (virtual outer periphery of the rotor 10) between the adjacent notches 12 is 60 degrees at the maximum. , A notch 12 may be formed. Also, the stator 1
Is preferably set to 6 slots. Note that the cutout portion 12 may not have a linear shape, and at least both oblique sides may have a curved shape.

According to the rotor 10 having the above structure, the magnet torque is at least as large as that of the conventional example.
Also, reluctance torque is generated as in the conventional case. The notch 12 not only prevents the leakage and short circuit of the magnetic flux of the permanent magnet 11 but also concentrates the magnetic flux of the permanent magnet 11 in the d-axis direction, so that the magnetic flux from the rotor 10 projects to the d-axis side. The structure has polarity. Therefore, since the magnetic flux is used effectively, the magnet torque becomes larger than before and the motor efficiency is increased.

It should be noted that one of the magnetic fluxes from the stator 1, q
Since the path of the magnetic flux from the axis to the other q-axis is secured, and the magnetic flux is interposed substantially perpendicular to the path of the magnetic flux from one d-axis to the other d-axis, the inductance difference between the d-axis and the q-axis (Ld− Lq)
Becomes large, and reluctance torque is obtained.

A notch 12 in the air layer is interposed between the permanent magnet 11 and the outer periphery of the rotor 10. That is, the permanent magnet 11 has a shape separated from the outer periphery of the rotor 10. Therefore, the eddy current on the surface of the permanent magnet 11 is reduced, that is, the loss of magnetic flux due to the eddy current is reduced.

Further, as a material of the permanent magnet 11, a ferrite magnet or a rare earth magnet is used. When a ferrite magnet is used, it is effective in reducing the cost of the motor. When a rare earth magnet is used, even if the permanent magnet 11 is smaller than the conventional example, at least the same magnet torque can be obtained. This is effective for increasing the torque and reducing the size. Therefore, various adaptive motors can be obtained in consideration of cost, torque, and the like.

Here, the manufacture of the rotor 10 will be described. A core laminating method (automatic laminating method) in which an electromagnetic steel sheet is punched out by an automatic press using a core press die and integrally formed in the die is adopted. I do.

As shown in FIG. 3, in this press working step, the core of the rotor 10 is punched. The outer periphery of the core is punched into the shape of the notch 12, and the hole (center hole) 4a of the shaft 4 and the permanent magnet 11 Are punched out, and the punched core sheets 10a are laminated, caulked and fixed.

The permanent magnet 11 is buried in the hole of the core of the rotor 10 obtained by automatically pressing and laminating by the automatic lamination method by the IPM method. The permanent magnet 11 is magnetized and magnetized in a direction perpendicular to the q axis, and the adjacent permanent magnet 1
The surfaces opposite to each other have the same polarity.

The buried hole of the permanent magnet 11 and the notch 12
Is greater than or equal to the thickness t of the core sheet 10a (for example, t
To 3t). Thereby, there is no generation of burrs and the like at the time of core manufacturing described later, and the yield of core manufacturing is improved. That is, the manufacturing cost can be reduced, and the mechanical strength of the core can be maintained. In particular, the core strength during rotation is maintained, and the reliability of the motor is also improved.

As shown in FIG. 4, in order to prevent the permanent magnet 11 from moving within the core or jumping out of the core, the lids (terminal plates) 1 are provided at both ends of the laminated core in the above-described fixing.
3 and pass the rivet 14 for caulking.
Note that FIG. 4 will not be described because other parts are the same as in FIG. 2, but when punching the core sheet 10a, holes in the rivets 14 are also punched.

The rivet 14 is preferably passed through the d-axis between the rivet 14 and the permanent magnet 11 with a margin, and is preferably made of a magnetic material having a high magnetic permeability so as to reduce disturbance of magnetic flux. In addition, as for caulking of the core, rivet 1
If the staking is formed at the time of pressing and laminating the core sheet 10a in addition to the passing through the core sheet 10a, the fixing strength of the core can be further increased.

If the high-torque, high-efficiency motor described above is used as, for example, a compressor motor of an air conditioner, the cost of the air conditioner can be reduced and the operating efficiency of the air conditioner can be increased. In FIG. 1, FIG.
Although the U-phase, W-phase, and V-phase windings are applied to the stator 1 having 24 slots in accordance with the above, the number of slots may be other, for example, 6 slots and concentrated winding is preferable.

FIG. 5 is a schematic plan view of a rotor of a magnet motor showing a modification of the first embodiment. In the drawing, the same parts as those in FIG. 2 are denoted by the same reference numerals, and redundant description will be omitted.

In FIG. 5, the rotor 20 has a pair of holes (flux barriers) 22a and 22b extending toward the permanent magnet 21 adjacent to the end of the permanent magnet 21 on the shaft 4 side.
Is formed. Note that the pair of holes 22a and 22b are integrated with the hole in which the permanent magnet 21 is embedded. In this case, the width of the pair of holes 22a and 22b should be at least １ ／ or less of the width of the short side of the permanent magnet 21.

The permanent magnet 21 may be the same as the permanent magnet 11 of the first embodiment, but the holes 22a and 22b can be formed reliably if the length of the long side is shortened somewhat. If the width of the permanent magnet 21 is increased by an amount corresponding to the shortening of the permanent magnet 21, the magnet torque can be made substantially equal to that of the first embodiment.

The pair of adjacent holes 22a and 22b is provided between the tip of one pair of holes 22a and 22b and the tip of the other pair of holes 22a and 22b.
A bridge k1 having a thickness of 0a or more is formed. Thereby, the leakage and short circuit of the magnetic flux of the permanent magnet 21 are reduced as compared with the permanent magnet 11 of the first embodiment.

The manufacture of the rotor 20 is the same as that of the previous embodiment. When the core of the rotor 20 is punched, the hole (center hole) 4a of the shaft 4, the hole for embedding the permanent magnet 11 and the holes 22a, 22a, 22b is punched, and the punched core sheets 10a are laminated, caulked and fixed.

Accordingly, there is no generation of burrs at the time of manufacturing the core of the rotor 20, and the yield of manufacturing the core is improved. That is, the manufacturing cost can be reduced, and the mechanical strength of the core can be maintained. In particular, the core strength during rotation is maintained, and the reliability of the motor is also improved. In addition,
The other parts of the rotor 20 and the manufacture thereof are the same as those of the first embodiment, and the description thereof will be omitted.

FIG. 6 is a schematic plan view of a rotor of a permanent magnet motor according to a second embodiment. In the drawing, the same parts as those in FIG. 2 are denoted by the same reference numerals, and redundant description will be omitted. FIG.
In this case, the rotor 30 has a notch 12 between the end (the outer peripheral end) of the permanent magnet 11 and the outer periphery of the rotor 30.
A hole 31 having the same shape as that of FIG.

The hole 31 is a flux barrier having a shape substantially similar to the notch 12, that is, a shape in which the length of both oblique sides of the notch 12 is slightly shortened. The core sheet 1 is provided between the outer peripheral side arc of the hole 31 and the outer periphery of the rotor 30.
The predetermined width is equal to or more than the thickness t of 0a (for example, t to 3t).
Therefore, according to the present embodiment, the same effects as those of the first embodiment can be obtained. Regarding the strength of the core mechanism,
Since there is a certain width between the rotor 1 and the outer periphery of the rotor 30, there is no influence on the strength.

When manufacturing the rotor 30 having the above-described structure, the core laminating method (automatic laminating method) is applied as in the above-described embodiment, and the core of the rotor 30 is punched out in the pressing process. , The hole in which the permanent magnet 11 is embedded, and the hole 31 of the flux barrier are punched, and the core sheet 10a punched out of these holes is laminated, caulked, and fixed. In the manufacture of the rotor 30, as described in the embodiment shown in FIGS.
In addition to embedding 1, rivets are passed through with terminal plates attached to both ends.

Further, a modification of the first embodiment is applied to this embodiment, and the flux barriers 22a and 22b shown in FIG. In this case, the permanent magnet 11 is
If the size is the same as that of the permanent magnet 21 shown in (1), leakage of magnetic flux and short circuit can be prevented without reducing magnet torque.

FIG. 7 is a schematic plan view of a rotor showing a third embodiment of the present invention. In the drawing, the same parts as those in FIG. 2 are denoted by the same reference numerals, and redundant description will be omitted.

In FIG. 7, the rotor 40 is formed by forming a wide notch 41 in place of the notch 12 shown in FIGS. The notch 41 is used for the permanent magnet 11
Is longer than the notch 12, that is, the straight line perpendicular to the q-axis is longer than that of the first embodiment, which is a large flux barrier.

Therefore, according to the present embodiment, the leakage and short circuit of the magnetic flux of the permanent magnet 11 are reduced as compared with the first embodiment. In addition, this embodiment has the same operations and effects as those of the first embodiment, and the manufacturing of the rotor 30 may be the same as that of the first embodiment.

The flux barriers 22a and 22b shown in FIG. 5 are formed on the rotor 40 by applying a modification of the first embodiment to this embodiment. In this case, the permanent magnet 11 is
If the size is the same as that of the permanent magnet 21 shown in (1), leakage of magnetic flux and short circuit can be prevented without reducing magnet torque. In addition, if the second embodiment is applied to this embodiment, that is, if the notch 41 is a hole similar to the hole 31,
The same operation and effect as the second embodiment can be exhibited.

[0046]

According to the present invention described above, the following effects can be obtained. According to the present invention, a permanent magnet having a rectangular cross section in the radial direction is embedded along a q-axis in a rotor inside a stator, and a d-axis is provided near an q-axis of the outer periphery on the end side of the permanent magnet. Forming a wide flux barrier in the direction
The permanent magnets are arranged at equal intervals in the circumferential direction by the number of poles, and the longer side of the rectangular cross section is used as a magnetic pole, and the opposite side of the longer side of the adjacent permanent magnet is magnetized to the same pole. Therefore, the eddy current can be reduced by the flux barrier between the permanent magnet and the outer periphery of the rotor. Moreover,
Since the magnetic flux generated by the permanent magnet can have saliency in the d-axis direction, the magnetic flux can be used effectively,
As a result, there is an effect that the magnet torque can be improved without lowering the reluctance torque, and the efficiency of the motor can be increased.

Since the rotor of the permanent magnet motor of the present invention forms a flux barrier of a pair of holes extending in the direction of the permanent magnet adjacent to the end of the permanent magnet on the shaft side, the above-described effects can be obtained. In addition, there is an effect that the leakage and short circuit of the magnetic flux of the permanent magnet can be further reduced, and the magnet torque can be further improved.

[Brief description of the drawings]

FIG. 1 is a schematic plan view of a permanent magnet electric motor according to a first embodiment of the present invention.

FIG. 2 is a schematic plan view of a rotor for explaining the permanent magnet motor shown in FIG.

FIG. 3 is a schematic side view of a rotor for explaining the permanent magnet electric motor shown in FIG. 1;

FIG. 4 is a schematic plan view of a rotor for explaining the permanent magnet electric motor shown in FIG. 1;

FIG. 5 is a schematic plan view of a rotor of a permanent magnet motor according to a modification of the first embodiment shown in FIG. 1;

FIG. 6 is a schematic plan view of a rotor of a permanent magnet electric motor showing a second embodiment of the present invention.

FIG. 7 is a schematic plan view of a rotor of a permanent magnet motor according to a modification of the third embodiment of the present invention.

FIG. 8 is a schematic plan view of a conventional permanent magnet motor.

[Explanation of symbols]

 Reference Signs List 1 stator 4 shaft 10, 20, 30, 40 rotor 10a core sheet 11, 21, permanent magnet 12, 41 notch (flux barrier) 14 rivet 22a, 22b hole (a pair of flux barrier) 31 hole (flux barrier) k1 t Core sheet thickness

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H02K 21/14 H02K 21/14 MF term (Reference) 5H002 AA03 AA09 AB07 AE08 5H619 AA01 AA07 BB01 BB06 BB22 BB24 PP02 PP04 PP08 5H621 GA01 GA04 GA16 HH09 JK02 JK05 5H622 AA03 CA02 CA13 CB05 CB06 PP11 PP14 PP16

Claims (8)

[Claims] 1. A permanent magnet motor having a rotor inside a stator that generates a rotating magnetic field, wherein the rotor includes:
A permanent magnet whose cross section is rectangular in the radial direction is embedded along the q axis, and q of the outer periphery is q at the end side of the permanent magnet.
A wide flux barrier is formed in the d-axis direction in the vicinity of the axis, the permanent magnets are arranged at equal intervals in the circumferential direction by the number of poles, and the longer side of the rectangular section is used as a magnetic pole, and the adjacent permanent magnets A permanent magnet motor characterized in that the opposite sides of the long side are magnetized to the same polarity. 2. A permanent magnet motor having a rotor inside a stator that generates a rotating magnetic field, wherein the rotor includes:
A permanent magnet having a rectangular cross section in the radial direction is embedded along the q-axis, and a flux barrier is formed in the d-axis direction near the q-axis of the outer periphery on one end side of the permanent magnet, At the other end of the permanent magnet, a flux barrier of a pair of holes extending in the direction of the adjacent permanent magnet is formed, and the permanent magnets are arranged at equal intervals in the circumferential direction by the number of poles, and have a rectangular cross section. A permanent magnet electric motor characterized in that a long side is a magnetic pole and adjacent long sides of the permanent magnet are magnetized to the same side. 3. The flux barrier formed in the vicinity of the q-axis is a notch having a groove-like outer periphery, and the notch is
The shape which opened in the said d-axis direction by the side parallel to the edge part of the said permanent magnet, and the edge | side which is the same length or longer than the edge part, and two sides which are acute-angled with respect to the said q axis | shaft. 3. The permanent magnet electric motor according to 1 or 2. 4. A flux barrier formed near the q-axis is a hole, the hole being parallel to an end of the permanent magnet,
And a side having the same length or a side longer than the same end and the q
It has a shape that is open in the d-axis direction by two sides that are acute to the axis and an arc along the outer periphery of the rotor,
The permanent magnet electric motor according to claim 1 or 2, wherein a distance between the hole and an outer periphery of the rotor is equal to or greater than a thickness of a core sheet constituting the rotor. 5. The permanent magnet electric motor according to claim 2, wherein a distance between a tip of the pair of holes and a tip of a pair of adjacent holes is equal to or larger than a thickness of a core sheet constituting the rotor. 6. The rotor according to claim 1, wherein a core of the rotor is fixed through a rivet on a d-axis in a region between the permanent magnets, and the rivet is made of a magnetic material. Permanent magnet motor. 7. The permanent magnet motor according to claim 1, wherein the material of the permanent magnet is a ferrite magnet or a rare earth magnet. 8. The rotor according to claim 1, wherein the rotor is punched out of an electromagnetic steel plate by an automatic press, and is automatically laminated in a mold, and the permanent magnet is embedded in a hole punched out by the automatic press. 8. The permanent magnet electric motor according to 5, 6, or 7.