JP3350971B2 - PM type vernier motor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a PM (permanent magnet) type vernier motor having improved performance and a high torque.

[0002]

2. Description of the Related Art Conventionally, there are various motors, one of which is a so-called vernier motor. The vernier motor, has a stator iron core 1 and the rotor core 2, as shown in FIG. 8, it rotates with a plurality of slots (8 in the slot number Z ₁ 12) is provided in the stator core 1 A plurality of slots (slot number Z ₂
In FIG. 8, 10) is provided, and the stator core has a three-phase winding (not shown) similar to that of a normal AC machine. Moreover, a slot number Z ₂ of the number of slots Z ₁ stator core 1 and the rotor core 2 Z ₂ -
When the relationship of Z ₁ = ± 2P (where 2P is the number of poles of the stator three-phase winding) is selected, the rotation speed is 120 f / Z.
₂ (rpm), and it has been found that ω _m = 2ω / Z _{2 when} represented by the rotational angular velocity ω _m and the angular frequency ω. Therefore, the angular frequency ω and the number of slots Z _{2 of the} rotor core ₂
Depends on the rotation speed.

However, in this vernier motor, there has been a problem that the maximum torque, ie, the pull-in torque, which can be synchronized with overcoming the inertia of the load, is small, and the escape torque due to the displacement of the rotor is also small. . Therefore, in order to obtain a large and stable steady torque, the number of slots Z ₂ , Z ₁ is selected to have a relationship of Z ₂ −Z ₁ = ± P, and at least one of the stator core 1 and the rotor core 2 is permanently mounted. A structure in which a magnet (PM) is embedded is disclosed in 1991-270665.

However, the present inventors have attempted to further improve the torque characteristics of the PM type vernier motor, and have completed the PM type vernier motor which has obtained a high torque.

[0005]

SUMMARY OF THE INVENTION To achieve the above object, the present invention provides: (1) a stator core having a slot number Z ₁ ;
A rotor core having a slot number Z ₂ at an equal pitch,
When P is the number of pole pairs, Z ₂ = Z ₁ + P or Z ₂ = Z ₁ −
A three-phase winding having a number of pole pairs P is accommodated in a slot of the stator core, and the rotor core is opposed to the stator core by a block divided into two along the axial direction. The two blocks are fixed to the shaft at positions shifted from each other in the circumferential direction by 1/2 of the rotor slot pitch, and are permanently attached to at least one of the slots of the stator core and the rotor core. In a PM type vernier motor in which magnets are embedded and all magnets are magnetized in the same direction for each block, and the magnets are magnetized in both blocks so that the polarities of the magnets are opposite to each other.

[0006] (2) and a stator core having a number of slots Z _1, and a rotor core having a number of slots Z ₂ at an equal pitch, Z ₂ = Z ₁ + P as pole logarithm P, or Z ₂ = Z
_1- P, and a three-phase winding having P pole pairs is accommodated in a slot of the stator core.
At least one of the slot and all slots of the rotor core
Permanent magnets are embedded in all slots of
DC magnetization generated by permanent magnets
The bundle passes from the iron core through the frame, bracket, bearing, and shaft.
PM type vernier motor with a structure that prevents circulation

A permanent magnet is projected into an air gap to
Or forms a structure to increase the fundamental component of the click, the three-phase windings as a fractional-slot winding and phase per pole of the stator windings q
The number of slots, a, was set to small slots on the stator teeth.
In this case, add 1 to the number of small slots provided in one stator tooth.
If there is no small slot, set to 1
Structure to reduce 6aq ± 1st harmonic component of torque
Is characterized by increasing the torque by making

Further, the present invention provides a structure having a small slot in a gap surface of a stator tooth.

[0009]

[Action] peak value of the torque of the PM type vernier motor T _m
Is represented by the following equation (Equation 1).

[0010]

(Equation 1) Where P is the number of pole pairs, Z ₂ is the number of rotor slots, D is the air gap side of the stator core diameter, l _a is the core effective length, N
₁ is the number of series conductors in the stator winding, I ₁ is the effective value of the stator current, q is the number of slots for each phase of the stator winding, and a is the number of small slots provided in one tooth. An integer obtained by adding 1 to k
_w1 and k _w (6aq ± 1) the fundamental wave, respectively and (6a
q ± 1) Winding coefficient for the higher harmonic, B _m1 is the peak value of the fundamental wave magnetic flux density generated by the permeance pulsation by the permanent magnet and the slot, and B _m (Z ₂ / P) is the permanent magnet accommodated in the rotor slot. Z ₂ / P = 6a caused by
q ± 1st harmonic magnetic flux density peak value, T _m1 is the peak value of torque generated by fundamental wave magnetic flux density B _m1 and stator current I ₁ , T _m (Z ₂ / P) is 6aq ± 1st harmonic magnetic flux The peak value of the torque generated by the density B _m (Z ₂ / P) and the stator current I ₁ .

[0011] torque T _m1 In the above equation (1), the dimensions D, l _a, if amps the number of conductors N ₁ I ₁ and the fundamental wave winding count k _w1 of the stator windings are the same, Z ₂ / It is under the influence of P and B _m1 . There is a correlation between _Bm1 and the value of (slot width) / (gap length), and the larger the latter value, the larger the value of _Bm1 . Here, increasing the slot width in an attempt to increase the B _m1, since the dimension D is constant becomes smaller rotor slot number Z _2, Z ₂ / P decreases, B _m1 is increased instead Z ₂ / P Becomes smaller. Therefore, if the number of pole pairs P is reduced so that Z ₂ / P is not reduced, remarkable magnetic saturation may occur due to an increase in the stator current I _{1. If} the gap length is increased to avoid this, B _m1 decreases. . Therefore, the permanent magnets are projected so that B _m1 does not decrease even if the gap length is increased, and the slot width is increased to decrease the number of rotor slots Z _{2 and the} number of pole pairs P is decreased to increase the gap length. Instead of using a permanent magnet protruding, B _m1 can be increased and the torque T _m1 can be increased.

Further, T _m, which is the second term in [Equation 1], is used.
(Z ₂ / P) has a negative sign, and the fundamental wave torque T _m1 of the first term
Because it has the effect of reducing the effective torque T _m acts in a direction to cancel, it is desirable to reduce. In the second term, 6aq ± first-order harmonic magnetic flux density B _m (Z ₂ /
P) is the peak value of the component to the spatial distribution of the slot pitch of the magnetic flux density of the permanent magnets housed in the rotor slots as one wavelength is determined by the material and the gap length of the permanent magnets, they and maximum B _{m1 Bm} (Z ₂ / P) also has a large value when it is designed so that it cannot be changed freely. Therefore, in order to reduce the _{T m (Z 2 / P)} , it is conceivable to reduce the k _w (6aq ± 1), when the stator winding is an integer slot winding 6AQ
The ± 1st order is a slot harmonic, and the absolute value of k _w (6aq ± 1) is equal to k _w1 and close to 1. Therefore, by using a fractional slot winding, k _w (6aq ± 1) is reduced, and T _m (Z ₂ / P) is reduced.

[0013]

An embodiment of the present invention will now be described with reference to FIGS. FIG. 1 shows a rotor 10 and a stator 11. In FIG. 1, the stator 11 is formed with slots 11a of equal pitch on the inner periphery thereof, and the number Z ₁ (FIG.
Then 6). This slot 11a has a three-phase winding 12
U, V, and W are applied to generate a rotating magnetic field having 2P poles (P is the number of pole pairs, P = 1 in FIG. 1).
Further, a permanent magnet 15 is embedded in the entrance of the slot 11a. On the other hand, the rotor 10 has slots 10c of equal pitch on the outer periphery thereof, and has the number Z ₂ (7 in FIG. 1). The permanent magnet 16 is embedded in all the slots 10c of the rotor 10. These permanent magnets 15 and 16 are magnetized so that all magnets have the same polarity toward the center in the radial direction as shown in FIG. And, to these slots number _{Z 1, Z 2, Z 2} = Z 1 + P or Z ₂ = Z ₁ if -P made having a relationship is formed (in FIG. 1 Z ₂ =
Z ₁ + P).

Here, the permanent magnets 15 and 16 have a structure protruding into the gap, and have a large gap length, and protrude into the gap as shown in FIG. 2B, for example. In FIG. 2B, as an example, the stator 11 and the rotor 1
0 shows a case where the permanent magnets 15 and 16 having a width of 10 mm are protruded by 0.17 mm into a gap having a length of 0.5 mm.

Focusing on the magnetic circuit in FIG. 1, the magnetic flux generated by each magnet forms a magnetic path closed between the magnet and the teeth via a gap. A permanent magnet causes a certain magnetic field difference between the outer circumference and the inner circumference of the rotor core, thereby generating a magnetic flux having a magnetic path of the stator core-frame-bracket-bearing portion-shaft-fixed core, which is harmful to the bearing. There is a possibility that such a phenomenon may occur. Two methods have been devised to prevent this.

As shown in FIG. 3, the rotor 10 of one specific example has two blocks 10a, 10a along the axial direction.
b, which is an AB plane which is a gap plane of the block 10a and a CD which is a gap plane of the block 10b.
The plane is a plane where the permanent magnets 15 and 15 accommodated in the slots are arranged on the AB plane and the CD plane so that magnetic flux passes in different directions.
The magnetization directions of 16 are opposite to each other. For this reason, a closed magnetic path such as an arrow of block 10a-stator core 11-block 10b-axis-block 10a is formed with respect to the magnetic flux due to the above-mentioned constant magnetic potential difference, so that the magnetic flux passes through the bearing portion. Can be prevented.

Further, since the block positions of the blocks 10a and 10b are fixed to the shaft 14 such that both slot positions are shifted from each other in the circumferential direction by ス ロ ッ ト slot pitch, both blocks are generated. The torque is in the same direction.

FIG. 3 shows a first specific example. In the second specific example, the rotor core is not divided into two blocks as described above. By providing a non-magnetic portion in the portion, it is possible to prevent magnetic flux from passing through the bearing 19. In FIG. 4, the DC magnetic flux generated by the permanent magnet passes through a magnetic path of the stator magnetic flux 11, the frame 17, the bracket 18, the bearing 19, the shaft 14, the rotor core 10, and the stator core 11.
Is made of an aluminum frame made of a non-magnetic material, the circulation of the DC magnetic flux can be easily prevented.

Although the description has been given of the electric motor, by supplying mechanical power to the shaft from the outside,
It can also operate as a generator.

Although the description so far has been made with a combination of a small number of slots as shown in FIG. 1, when a low rotational angular velocity is required, the number of slots may be increased. In this case, since Z ₁ and Z ₂ have a relationship of Z ₂ = Z ₁ ± P, there is a limit in increasing Z ₂ in the structure shown in FIG. Therefore, as in FIG. 5, a small slot provided in the teeth in addition to the slot that contains the windings, the total number of slots of the sum of the two is taken as Z _1, Z ₂ with respect to the total number of slots Z ₁ = Z ₁
Since may be selected Z ₂ as ± P holds, in such a structure can sufficiently large Z _2, can be easily obtained extremely low speed.

FIG. 5 shows a gap portion of this modified motor. A winding slot 11a into which a three-phase winding is inserted is formed on the inner peripheral side of the stator core 11, and the gap between the winding slots 11a is formed. A small slot 11c facing the rotor is also formed on the inner peripheral side of the tooth 11b. The entrance of the winding slot 11a and the small slot 11c have the same width. In this case, the total number of slots and Z _1,
The slot pitch φ ₁ of the stator core 11 is equal to 2π / Z ₁ . The inlet of the winding slot 11a and the small slot 11c may have the same width in order to reduce the torque ripple during operation, but the present invention is not particularly limited to this. At the entrances of the small slot and the winding slot, a permanent magnet 15 is embedded so as to protrude into the gap.

[0022] On the other hand, the slot 10c of the slot number Z ₂ in the outer peripheral side of the rotor core 10 is formed, the slot 1
The slot pitch φ _{2 of} 0c is equal to 2π / Z ₂ . The permanent magnets 16 are also provided in the slots of these rotors.
Are protruding and embedded in the gap.

Now, six types of specific motor models A to F will be described. Table 1 shows the main specifications of each model. Among them, A, B, C, D and E are models in which the permanent magnets do not protrude as shown in FIG. 2A, and only F is a model in which the permanent magnets protrude as shown in FIG. 2B.

[Table 1]

[0024] According to this table 1, A, B, C are 8-pole model, gradually increasing the rotor small number of slots Z ₂ together with stator total number of slots Z ₁ by the small slot as shown in FIG. 5 In the case of D, E and F, Z ₂ / P is model A by reducing Z ₂ and making the number of poles four.
The model D has a gap length of 0.25, the same as 8 poles, while the model E and F have a wider gap length of 0.5 while maintaining the same slot width as D, E, and D compared to A, B, and C. , F
The conditions are the same except that the outside diameter of the stator is 1.11 times.

When the characteristics of the above model are compared as shown in FIGS. 6 and 7, the T _m -I ₁ characteristic shown in FIG.
As apparent from the B _m1 -I ₁ characteristics shown in FIG.
A significant increase in torque to be increased the Z ₂ at C decreases B _m1 is not recognized, also B _m1 since magnetic saturation is significantly teeth with increasing current in Model D is rapidly decreased are doing. Therefore, when the gap length is increased to 0.5 in order to avoid magnetic saturation, in the model E in which the permanent magnet does not protrude, the B _m1 becomes significantly smaller than that in the model D, and thus the torque T
_{m is} also smaller. B when the gap length is increased
_As shown in FIG. 2 (b), in order to avoid a decrease in _m1 , B _m1 and T _m were significantly increased in model F in which the permanent magnet was projected into the gap as compared with model E. Model E, the T _m -I ₁ Comparison of F shown in Table 2 below.

[0026]

[Table 2] As described above, in the model F, the torque can be significantly increased by projecting the magnet into the gap.

Next, the fractional slot winding will be described.
Assuming that a is a number obtained by adding 1 to the number q of slots of one pole and one phase and the number of small slots provided in the stator teeth described above, Z
₁ = 6aqP, and from the relationship of Z ₂ = Z ₁ ± P, the number of permanent magnets per pole pair of the rotor is Z ₂ / P = Z ₁ / P
Since ± 1 = 6aq ± 1, among the harmonic components of the magnetic flux density due to the permanent magnet, the component of this order has a remarkably large value. The order of harmonics contained in the stator winding magnetomotive force distribution in the gap is 6l ± 1st order (1 is a positive integer). Among them, the 6aq ± 1st order component is contained in the rotor slot. Since the order is the same as that of the dominant harmonic component generated by the permanent magnet, a torque is generated, and its value is shown in the second term of [Equation 1]. This torque T _{m (Z2 / p)} becomes a torque in the opposite direction to the torque T _m1 due to the fundamental wave magnetic flux, and reduces the effective torque.
It is desirable that _{m (Z2 / p)} is small. As is apparent from the second term of equation [Equation 1], may be reduced k _W (6aq ± 1) To reduce the torque T _{m (Z2 / p),} when the normal integral slot since its absolute value for 6AQ ± 1-order is a so-called slot harmonic becomes a value close to 1 equals _{k W1, T m (Z2 /} p) becomes a considerable value.

Now, assuming that I ₁ = 8 (A), the torque due to the harmonic magnetic flux is shown in Table 3 for the models A, B, C, D, and F shown in Table 1 above.

[Table 3]

As shown in Table 3, as Z ₂ / P is smaller, the ratio of the harmonic torque is larger, and T _{m (Z 2 / p )} / T _m (%) is larger. This would reduce the effective torque T _m. It was noticed that k _W in the case of integral slot as previously described (6aq ± 1) is because having a value close to 1, k _W by a fractional-slot winding in (6aq ± 1) Decreasing the value, harmful T
It was clarified that _{m (Z2 / p)} can be reduced.

When a four-pole, fractional slot winding with q = 2.5 is used, Z ₁ = 30 and Z ₂ = 32, and a calculation example in this case is shown in Table 3 as a model G. By comparing this with a model A~F integer _{slot, T m (Z2 / p)} / value of the T _m is clear that significantly reduced by a fractional-slot winding, reduction of the effective torque can be prevented It turns out that it becomes.

Although the description so far has been made with respect to a normal structure in which the rotor is inside the stator, an outer rotor type in which the rotor is arranged on the outer periphery of the stator may be used.

[0032]

As described above, according to the present invention, P
Z in M type vernier motor_Two= Z ₁± P slot
For permanent magnets with permanent magnets, the permanent magnet
Raise fundamental wave torque by projecting into gap
And fractional slot winding reduces negative harmonic torque
The effective torque of the PM type vernier motor.
Could be increased.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of an embodiment of the present invention.

FIG. 2 is a layout diagram of permanent magnets.

FIG. 3 is a cross-sectional view along the axial direction of the motor.

FIG. 4 is a configuration diagram of an end of a motor.

FIG. 5 is an explanatory diagram of a small slot.

FIG. 6 is a T _m -I ₁ characteristic diagram.

[7] B _m -I ₁ characteristic diagram.

FIG. 8 is a configuration diagram of a conventional vernier motor.

[Explanation of symbols]

 Reference Signs List 10 Rotor 10a, 10b Block 10c, 11a, 11b Slot 11 Stator 13, 15, 16 Permanent magnet

Claims (8)

(57) [Claims] _1. A stator core having a number of slots Z ₁ ,
A rotor core having a slot number Z ₂ at an equal pitch,
When P is the number of pole pairs, Z ₂ = Z ₁ + P or Z ₂ = Z ₁ −
A three-phase winding having the number of pole pairs P is accommodated in the slot of the stator core, and the rotor core is opposed to the stator core by a block divided into two along the axial direction. Then, the two blocks are fixed to the shaft at positions shifted from each other in the circumferential direction by の of the rotor slot pitch, and a permanent magnet is placed in at least one of all the slots of the stator core and the rotor core. In a PM type vernier motor in which all magnets are magnetized in the same direction for each embedded block and for both blocks, and the polarities of the magnets are reversed in both blocks, the stator core of the embedded permanent magnet is used. And at least one permanent magnet of the rotor core protrudes into the air gap
And a PM type vernier motor having a structure for increasing a fundamental wave component of torque . 2. A stator core having a number of slots Z ₁ ,
A rotor core having a slot number Z ₂ at an equal pitch,
When P is the number of pole pairs, Z ₂ = Z ₁ + P or Z ₂ = Z ₁ −
A three-phase winding having the number of pole pairs P is accommodated in the slot of the stator core, and the rotor core is opposed to the stator core by a block divided into two along the axial direction. Then, the two blocks are fixed to the shaft at positions shifted from each other in the circumferential direction by の of the rotor slot pitch, and a permanent magnet is placed in at least one of all the slots of the stator core and the rotor core. In a PM type vernier motor in which all magnets are magnetized in the same direction for each block embedded and both blocks are magnetized so that the magnets have opposite polarities, the three-phase winding is a fractional slot winding . Yes, q is stator winding
The number of slots for each pole and phase of the wire, a is a small slot on the stator tooth
Small slot provided on one stator tooth if provided
Number plus 1 when no small slot is provided
When 1 is set, 6aq ± 1st harmonic component of torque is reduced.
PM type vernier motor characterized by a structure that reduces Becomes Z ₂ = Z ₁ + P or Z ₂ = Z ₁ -P pole as logarithm P and a rotor core having a 3. A number of slots Z ₂ in the stator core and an equal pitch having a slot number Z ₁ forming relationship, the three-phase windings of the pole pairs P is the slot of the stator core is housed, embedding a permanent magnet in at least one of all slots in all slots of all slots and the rotor core of the stator core In the PM type vernier motor, the structure is such that all magnets are magnetized in the same direction and the DC magnetic flux generated by the permanent magnet is prevented from circulating from the iron core through the frame, bracket, bearing, and shaft. At least one of the stator core and the rotor core among the inserted permanent magnets protrudes into the air gap.
And a PM type vernier motor having a structure for increasing a fundamental wave component of torque . 4. The stator core having the number of slots Z ₁ and the rotor core having the number of slots Z ₂ at the same pitch are defined as Z ₂ = Z ₁ + P or Z ₂ = Z ₁ -P, where P is the number of pole pairs. forming relationship, the three-phase windings of the pole pairs P is the slot of the stator core is housed, embedding a permanent magnet in at least one of all slots in all slots of all slots and the rotor core of the stator core A PM type vernier motor having a structure in which all magnets are magnetized in the same direction and a DC magnetic flux generated by a permanent magnet is prevented from circulating from an iron core through a frame, a bracket, a bearing, and a shaft. The phase winding is a fractional slot winding and q is a stator winding
The number of slots for each pole and phase of the wire, a is a small slot on the stator tooth
Small slot provided on one stator tooth if provided
Number plus 1 when no small slot is provided
When 1 is set, 6aq ± 1st harmonic component of torque is reduced.
PM type vernier motor characterized by a structure that reduces 5. The number of slots Z ₁ A stator core having
Slot number Z at equal pitch _Two And a rotor core having
Z with P as pole pairs _Two = Z ₁ + P or Z _Two = Z ₁ −
Form a relationship P A three-phase winding with P pole pairs is provided in the stator core slot.
And The above rotor core is divided into two blocks along the axial direction.
Facing the stator core at Let these two blocks
In the circumferential direction by の of the rotor slot pitch
Fix to the shaft at the shifted position, At least one of the stator core and the rotor core
A permanent magnet is embedded in the lot, and all magnets are
While magnetizing in one direction, both blocks
PM type vernier motor that is magnetized so that the polarities are opposite to each other
At All slots of the stator core and all slots of the rotor core
Permanent magnets are embedded in the
Protrudes into the air gap, increasing the fundamental component of torque
PM type vernier motor characterized by the structure
Ta. 6. The number of slots Z ₁ With stator core and so on
Number of slots at pitch Z _Two P with the rotor core having
Z as pole pairs _Two = Z ₁ + P or Z _Two = Z ₁ -P
Form into a relationship, A three-phase winding with P pole pairs is provided in the stator core slot.
And All slots of the stator core and all slots of the rotor core
Permanent magnet embedded in at least one of all slots
And magnetize all magnets in the same direction,
DC magnetic flux generated from the iron core
Structure that prevents circulation through the shaft, bearings and shaft
PM type vernier motor All slots of the stator core and all slots of the rotor core
Permanent magnets are embedded in the
Protrudes into the air gap, increasing the fundamental component of torque
PM type vernier motor characterized by the structure
Ta. 7. The three-phase winding is a fractional slot winding.
Where q is the number of slots for each phase of the stator windings and a is fixed.
If the small teeth are provided with small slots, one stator tooth
Small slots are provided by adding 1 to the number of small slots provided
If it is not set to 1, the torque is 6aq ± 1
Characterized by a structure that reduces second harmonic components
A PM type vernier motor according to claim 1, 3, 5, or 6. 8. includes a small slot gap surface of the stator teeth of the stator core, characterized in that the small slot and winding was stator total number of slots Z ₁ the plus and videos are slots Claims 1, 2 , 3 , 4, 5, 6 or 7
PM type vernier motor.