JP2010088268A - Rotating electric machine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a rotating electric machine which can maintain high torque, has a low risk of resonance and eliminates the necessity of increasing the motor strength more than necessary. <P>SOLUTION: This rotating electric machine includes: a rotor 5 having P-units of permanent magnets 13 arranged substantially equally spaced on a circumference; and a stator 7 having S-units of slots arranged substantially equally spaced on a circumference. In the rotating electric machine, the relation between the number P of permanent magnets 13 and the number S of slots meets the following: P&ge;S+4 and P&lt;(5/4)&times;S, or P&le;S-4 and P&gt;(3/4)&times;S. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

  The present invention relates to a rotating electrical machine including a rotor having a plurality of magnetic poles arranged circumferentially at approximately equal intervals and a stator having a plurality of slots arranged circumferentially at approximately equal intervals.

Patent Document 1 discloses that n magnetic pole teeth arranged circumferentially at approximately equal intervals, a stator winding concentratedly wound on each magnetic pole tooth and connected in three phases, and each magnetic pole teeth face each other. M permanent magnet magnetic poles arranged at equal intervals over the entire circumference of the outer diameter side, the number n of magnetic pole teeth is 18 (1 + Z), and the number m of permanent magnet magnetic poles is 16 (1 + Z) Discloses a motor that is set to an integer of 1 or more. According to such a motor, since the least common multiple of the number of teeth n and the number of magnetic poles m is large, cogging becomes a high order and vibration amplitude due to cogging torque can be reduced.
JP 2000-201462 A

  However, although such a motor is excellent in terms of high torque and low cogging torque, there is a problem that vibration generated in the motor itself must be absorbed by the strength of the motor. In particular, in the motor shaft, there is no problem with respect to the strength in the rotational direction, that is, the torsional direction because the motor shaft is a shaft for transmitting torque, but there is some problem with respect to vibration generated in the direction orthogonal to the axial direction. Strength reinforcement is required.

  Therefore, an object of the present invention is to provide a rotating electrical machine that maintains a high torque and has a low risk of resonance and does not need to increase motor strength more than necessary.

  The present invention has been made to solve the above problems, and a rotating electric machine according to a first aspect of the present invention includes a rotor having P magnetic poles arranged at substantially equal intervals in a circumferential shape, and a circumferential shape. In a rotating electrical machine including a stator having S slots arranged at substantially equal intervals, the relationship between the number P of the magnetic poles and the number S of the slots is expressed by P ≧ S + 4 and P <(5/4) × S It is characterized by that.

  A rotating electrical machine according to a second aspect of the present invention includes a rotor having P magnetic poles arranged in a circumferential manner at approximately equal intervals, and a stator having S slots arranged in a circumferential manner at substantially equal intervals. In the rotary electric machine, the relationship between the number P of the magnetic poles and the number S of the slots is P ≦ S−4 and P> (3/4) × S.

  In general, during the rotation of the rotor, a suction or pulling force is generated from the stator. In other words, the rotor is subjected to vibrations corresponding to S slots, and a force that causes a Z-order deformation mode (Z is the difference between the number of magnetic poles P and the number of slots S) from the difference between the number of magnetic poles P and the number of slots S faces the stator. Will be potentially added in the direction of In the rotary electric machine according to the first and second inventions described above, since the order Z is 4 or more, the deformation of the rotor in the direction facing the stator is complicated, and the deformation is reduced accordingly.

  Therefore, according to the rotating electrical machine of the present invention, it is possible to reduce the deformation of the rotor during rotation and avoid vibrations that can cause resonance, so that it is not necessary to increase the motor strength more than necessary. Further, since the ratio between the number of magnetic poles P and the number of slots S is set close to 1, high torque can be maintained.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a schematic sectional view of an axial gap type rotating electrical machine according to an embodiment of the present invention.

  A rotating electrical machine 1 shown in FIG. 1 is a disk type motor, and includes a rotor 5 and a stator 7 in a case 3. The rotor 5 and the stator 7 are arranged to face each other in the rotor rotational axis direction through a gap (air gap) 9 between them.

  The rotor 5 has P permanent magnets 13 disposed at substantially equal intervals in the circumferential direction with respect to a disk-shaped rotor core 11 made of a magnetic material. These permanent magnets 13 are arranged at predetermined intervals so that the magnetic poles facing the stator are alternately different in the circumferential direction of the rotor core 11. The central portion 11a of the rotor core 11 is fixedly attached to the rotor rotating shaft 15, and both ends of the rotating shaft 15 are rotatably supported in the case 3 by bearings 16 so that the axial direction cannot be displaced.

  The stator 7 has S stator cores 21 wound with electromagnetic coils 19 and arranged at substantially equal intervals in the circumferential direction with respect to the back core 17. The stator 7 is disposed concentrically with the rotor 5 so that the stator core 21 faces the rotor 5 with the air gap 9 interposed therebetween. Further, the stator 7 is attached to the case 3 via a back core 17. Further, a cooling water passage 23 is provided in the case 3, and a coolant (not shown) for absorbing and cooling the heat generated by the stator 7 is circulated. An encoder 25 for detecting the rotational position of the rotor is provided at the end of the rotating shaft 15.

  In this embodiment, the number P of permanent magnets 13, that is, the number P of magnetic poles, and the number of stator cores 21, that is, the number S of slots between the stator cores 21, are P ≧ S + 4 and P <(5/4) × S. Meet. In another embodiment of the present invention, the number P of permanent magnets and the number S of stator cores satisfy the relationship of P ≦ S−4 and P> (3/4) × S.

  In the axial gap type rotating electrical machine shown in FIG. 1, when the electromagnetic coil 19 is excited by an inverter (not shown), a rotating magnetic field is formed in the circumferential direction of the stator 7, and P permanent magnets 13 having different magnetism alternately in the circumferential direction are formed. The embedded disk-like rotor 5 is attracted and repelled by the rotating magnetic field generated by the stator 7 and rotates at a synchronous speed with the rotating magnetic field.

  Next, the background of the inventor of the present invention will be described with reference to a conventional axial gap type rotating electrical machine having a slot number S of 18 and a magnetic pole number P of 20.

  In a general concentrated winding motor, when the number of slots is S and the number of magnetic poles is P, the magnetic attractive excitation force acting on the rotor has many components of the rotation S order and the stator facing direction | PS | In the example of the axial gap type with S = 18 and P = 20 here, the influence of the rotation 18th order and the influence of the surface secondary mode are potentially large. That is, there is a possibility that a low-order deformation mode (secondary surface in the example of FIG. 2) as shown in FIG. As a result, an amplitude corresponding to the disk strength of the rotor 5 and the size of the disk is generated, and depending on the number of rotations, resonance may occur, resulting in large vibrations. In particular, in a rotating electrical machine such as the axial gap type of the above-described embodiment, the problem of vibration becomes more prominent when the rotor diameter is increased in anticipation of higher torque.

  Therefore, in order to prevent such resonance, it is necessary to reinforce the rotor 5 or the like, or to avoid a low-order deformation mode as shown in FIGS. On the other hand, if the difference between the number of slots S and the number of magnetic poles P is simply increased, the torque may be reduced at the same time. Therefore, as a result of examining the relationship between the number of slots S and the number of magnetic poles P, the present invention has been achieved.

  More specifically, if the relationship between the number P of magnetic poles and the number S of slots satisfies P ≧ S + 4 or P ≦ S−4, it is possible to avoid third-order vibration or less that can cause resonance.

となるので、磁極数Ｐとスロット数Ｓとが同じときK_T=π/2となり、最大値１をとる。しかし、現実的には磁極数Ｐとスロット数Ｓとを等しくすることは、モータの回転方向を決められないことになるので（磁極とスロットが常に一対一で対向するので）、モータとして起動させることはできない。従って、高トルクを得るためには磁極数Ｐとスロット数Ｓの比率を１に近づける（磁極数Ｐとスロット数Ｓとの差を小さくする）ことが必要である。短節係数と、磁極数Ｐ及びスロット数Ｓの組合せとの関係を図４の表に示す。図中×印は、短節係数が最大となるものの磁極数Ｐとスロット数Ｓとが等しくモータとしては利用できないものを示している。この図から判るように、×印から離れる程、短節係数が悪化する。 Here, the relationship between the combination of the number of magnetic poles and the number of slots (hereinafter referred to as “slot combination”) and torque will be described. One index indicating the efficiency of the motor is a winding coefficient, and the winding coefficient is represented by a product of a distribution coefficient and a short node coefficient. Since the distribution coefficient is always 1 if multi-phase driving can be performed from the inverter, when considering the performance of the inverter, the short-pitch coefficient is an element that determines the relationship between the slot combination and the torque. The short node coefficient _KT is related to the number of magnetic poles P and the number of slots S.

Therefore, when the number of magnetic poles P and the number of slots S are the same, K _T = π / 2 and the maximum value is 1. However, in reality, making the number of magnetic poles P and the number of slots S equal makes it impossible to determine the rotation direction of the motor (because the magnetic poles and the slots always face each other one-on-one), so that the motor is started. It is not possible. Therefore, in order to obtain a high torque, it is necessary to make the ratio of the number of magnetic poles P and the number of slots S close to 1 (to reduce the difference between the number of magnetic poles P and the number of slots S). The relationship between the short node coefficient and the combination of the number of magnetic poles P and the number of slots S is shown in the table of FIG. In the figure, the crosses indicate that the number of magnetic poles P and the number of slots S are equal and cannot be used as a motor, although the short bar coefficient is maximum. As can be seen from this figure, the shorter the coefficient, the worse the short coefficient.

  From the above, the ratio of the number of magnetic poles P to the number of slots S in the present invention is P <(5/4) × S when P ≧ S + 4, and P> when P ≦ S−4. (3/4) × S.

  Further, the number of driving phases to the stator is preferably 5 or more. According to this, vibration can be further reduced.

  Furthermore, the number of drive phases is more preferably N or 2N (where N is an odd number of 7 or more). According to this, vibration can be further reduced.

  Furthermore, it is more preferable that the number S of slots is a multiple of the number N of driving phases. According to this, vibration can be further reduced.

  Moreover, (N, 2N, S, P), which is the relationship between the number of drive phases N, the number of slots S, and the number of magnetic poles P, is (9, 27, 32), (9, 27, 22), (18, 27, 32), (18, 27, 22), (18, 36, 42), (18, 36, 30), (18, 36, 44) or (18, 36, 28) Is more preferable. According to this, vibration can be further reduced.

In order to confirm the effect of the present invention, various drive phases (5 phases (forward winding only), 5 phases (forward / reverse winding), 3 phases (forward winding only), 3 phases (forward / reverse winding), 7 phases (forward / reverse winding)) The slot combination is axial using the evaluation function shown in the following formula (2) in the 7-phase (forward / reverse winding), 7-phase (forward / reverse winding), 9-phase (forward-only winding), 9-phase (forward / reverse winding)) The effect on vibration was quantified. The evaluation is performed by accumulating vibration modes generated in the rotor when each slot combination is rotated from 0 to 10,000 rotations. Specifically, as can be seen from Equation (2), the deformation of all harmonic vibrations and the resonance rotational speed are calculated in all vibration modes (0 to 4), and the deformation in each vibration mode and each harmonic vibration is calculated. The total value I obtained by dividing by the resonance speed is used as the evaluation value of the degree of risk. According to this, a low mode order is highly evaluated, and it is also highly evaluated for vibration when the rotational speed is low. In other words, even if high-order vibration occurs at high rotation, there is no risk of resonance as vibration, so the score is low. Conversely, if low-order vibration occurs at low rotation, the possibility of resonance is high. The score gets higher. According to such an evaluation method, the risk of resonance over the entire motor operating point can be compared fairly. It should be noted that strength problems are unlikely to occur in the fourth-order vibration mode, but noise or other problems may occur if a unique situation occurs, such as the fourth-order vibration continuing over the entire rotation range. Therefore, the evaluation score is set low and the evaluation target. Only vibration modes 0 to 3 may be evaluated. As for the higher harmonics, the higher order harmonics are not likely to have a large amplitude and cannot cause a problem in strength.

(5-phase (normal winding only) drive)
First, FIG. 5 visually shows the relationship between the slot combination and the risk of resonance in the case of the five-phase (only normal winding) drive by applying the above evaluation method. The smaller the value, the smaller the risk of resonance (the same applies hereinafter). As is clear from this result, the relationship between the number P of magnetic poles and the number S of slots is
P ≧ S + 4 and P <(5/4) × S or
If P ≦ S-4 and P> (3/4) × S, the risk of resonance is small, and the torque is smaller than that of a general motor in which the ratio of the number of magnetic poles P to the number of slots S is 2 to 3. It can be seen that a slot combination is obtained that is high, that is, P-to-S is close to 1: 1.

(5-phase (forward / reverse winding) drive)
FIG. 6 visually shows the relationship between the slot combination and the risk of resonance in the case of five-phase (forward / reverse winding) driving (equivalent to ten phases) by applying the above evaluation method. From this result, as in the case of five-phase driving, there is less risk of resonance, and a slot combination with a higher torque than that of a general motor is obtained. In particular, P ≧ S + 4 and P <(5/4) × S and P It can be seen that the evaluation is better than the case of five-phase driving in the region of ≦ S−4 and P> (3/4) × S, that is, there is less risk of resonance.

(3-phase (normal winding only) drive)
FIG. 7 visually shows the relationship between the slot combination and the risk of resonance in the case of three-phase (normal winding only) drive by applying the above evaluation method. From this result, the same improvement can be seen although the evaluation is slightly worse than in the case of five-phase driving.

(3-phase (forward / reverse winding) drive)
FIG. 8 visually shows the relationship between the slot combination and the risk of resonance in the case of three-phase (forward / reverse winding) drive (corresponding to six phases) by applying the above evaluation method. From this result, it can be seen that a slot combination that is better than that in the case of three-phase driving, that is, a risk of resonance is obtained.

(7-phase (normal winding only) drive)
FIG. 9 visually shows the relationship between the slot combination and the risk of resonance in the case of 7-phase (normal winding only) drive by applying the above evaluation method. From this result, as in the case of five-phase driving, there is less risk of resonance, and a slot combination with a higher torque than that of a general motor is obtained. In particular, P ≧ S + 4 and P <(5/4) × S and P It can be seen that the evaluation is better than the case of five-phase driving in the region of ≦ S−4 and P> (3/4) × S, that is, there is less risk of resonance.

(7-phase (forward / reverse winding) drive)
FIG. 10 visually shows the relationship between the slot combination and the resonance risk in the case of 7-phase (forward / reverse winding) driving (equivalent to 14-phase) by applying the above evaluation method. From this result, the risk of resonance is small as in the case of the seven-phase drive, and a slot combination having a higher torque than that of a general motor is obtained. In particular, P ≧ S + 4 and P <(5/4) × S and P It can be seen that the evaluation is better than the case of 7-phase driving in the region of ≦ S−4 and P> (3/4) × S, that is, there is less fear of resonance.

(9-phase (normal winding only) drive)
FIG. 11 visually shows the relationship between the slot combination and the vibration in the case of the nine-phase (normal winding only) drive by applying the above evaluation method. From this result, as in the case of five-phase driving, there is less risk of resonance, and a slot combination with a higher torque than that of a general motor is obtained. In particular, P ≧ S + 4 and P <(5/4) × S and P It can be seen that the evaluation is better than that in the case of five-phase driving in the region of ≦ S-4 and P> (3/4) × S, that is, there is less fear of resonance.

(9-phase (forward / reverse winding) drive)
FIG. 12 visually shows the relationship between the slot combination and vibration in the case of 9-phase (forward / reverse winding) drive (equivalent to 18 phases) by applying the above evaluation method. From this result, as in the case of the nine-phase drive, there is less risk of resonance, and a slot combination having a higher torque than that of a general motor can be obtained. In particular, P ≧ S + 4 and P <(5/4) × S and P It can be seen that the evaluation is better than that in the case of nine-phase driving in the region of ≦ S-4 and P> (3/4) × S, that is, there is less risk of resonance.

From the above evaluation, the relationship between the number P of magnetic poles and the number S of slots is
P ≧ S + 4 and P <(5/4) × S or
If P ≦ S-4 and P> (3/4) × S, the risk of resonance is small, and the torque is smaller than that of a general motor in which the ratio of the number of magnetic poles P to the number of slots S is 2 to 3. It can be seen that the slot combination is high, that is, the P pair S is close to 1: 1, and the vibration is less as the number of driving phases is larger.

  Note that a three-phase drive (equivalent to six phases) rotating electrical machine using forward and reverse coils can be driven by a three-phase inverter. FIG. 13 illustrates a case where a three-phase (forward / reverse winding) rotating electric machine having a slot combination with which the winding utilization ratio, cogging torque, etc. are good is driven by a three-phase inverter. The rotating electrical machine shown in FIG. 13 has 15 slots, 14 magnetic poles, 6 driving phases, 95.67% distribution coefficient, 99.45% short node coefficient, and 95.14% winding coefficient. is there. If it is a general three-phase drive, it can be energized only at the timing of electrical angles of 0, 120, and 240 degrees. However, in this example, a reverse winding coil is used, so that it is equivalent to energization of 60, 180, and 300 degrees. (The opposite of 0 degree is 180 degrees, so if the coils at 0 degree and 180 degrees are connected in parallel as a normal winding coil and a reverse winding coil, they can be simultaneously 0 with a single phase current. A degree and 180 degrees energization can be achieved, as is a 120 degree reversal of 300 degrees and a 240 degree reversal of 420 degrees (60 degrees).

  Although the present invention has been described based on the illustrated examples, the present invention is not limited to the above-described examples, and can be appropriately changed within the scope of the claims. For example, the present invention is a radial gap type rotation. The present invention can also be suitably applied to an electric machine.

  Thus, according to the rotating electrical machine of the present invention, it is possible to reduce the deformation of the rotor at the time of rotation and avoid the vibration that may cause resonance, so that it is not necessary to increase the motor strength more than necessary. Further, since the ratio between the number of magnetic poles P and the number of slots S is set close to 1, high torque can be maintained.

  In the rotating electrical machine of the present invention, the number of drive phases to the stator may be 5 or more, and according to this, vibration can be further reduced.

  In the rotating electrical machine of the present invention, the number of drive phases may be N or 2N (where N is an odd number equal to or greater than 7), and vibration can be further reduced.

  Furthermore, in the rotating electrical machine of the present invention, the number S of slots may be a multiple of the number N of drive phases, and according to this, vibration can be further reduced.

  Furthermore, in the rotating electrical machine of the present invention, the relationship between the number of drive phases N, the number S of slots, and the number P of magnetic poles (N or 2N, S, P) is (9, 27, 32). , (9, 27, 22), (18, 27, 32), (18, 27, 22), (18, 36, 42), (18, 36, 30), (18, 36, 44) or ( 18, 36, 28), and according to this, vibration can be further reduced.

  Moreover, the present invention can be suitably used for a disk-type motor in which the rotor and the stator are arranged opposite to each other in the rotor rotation axis direction, and according to this, it is possible to achieve even higher torque.

It is a schematic longitudinal cross-sectional view of the rotary electric machine of embodiment according to this invention. It is a schematic perspective view of the rotor with the deformation | transformation of a surface secondary mode taken out from the rotary electric machine which has the subject which this invention tends to solve. (A)-(d) is the schematic diagram which showed the magnetic attraction excitation force of the surface 0 order-surface 3rd acting on a rotor. The relationship between the short node coefficient and the combination of the number of magnetic poles P and the number of slots S is shown in the table. It is a figure showing the risk of a slot combination and resonance at the time of five phase (only normal winding) drive. It is a figure showing the slot combination and the risk of resonance at the time of 5 phase (forward / reverse winding) drive. It is a figure showing the risk of slot combination and resonance at the time of three-phase (only normal winding) drive. It is a figure showing the slot combination and the risk of resonance at the time of 3 phase (forward / reverse winding) drive. It is a figure showing the risk of the slot combination and resonance at the time of 7 phase (normal winding only) drive. It is a figure showing the risk of slot combination and resonance at the time of 7 phase (forward / reverse winding) drive. It is a figure showing the risk of a slot combination and resonance at the time of 9 phase (normal winding only) drive. It is a figure showing the risk of the slot combination and resonance at the time of 9 phase (forward / reverse winding) drive. It is a table | surface which shows the phase shift which generate | occur | produces when the three-phase drive (equivalent to 6 phase) rotary electric machine using a forward / reverse winding coil is driven with a three-phase inverter.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Rotating electrical machine 3 Case 5 Rotor 7 Stator 9 Air gap 11 Rotor core 13 Permanent magnet 15 Rotor rotating shaft 16 Bearing 17 Back core 19 Electromagnetic coil 21 Stator core 23 Cooling water path 25 Encoder

Claims (7)

In a rotating electrical machine comprising a rotor having P magnetic poles arranged in a circumferential manner at approximately equal intervals, and a stator having S slots arranged in a circumferential manner at substantially equal intervals,
The relationship between the number P of the magnetic poles and the number S of the slots is
P ≧ S + 4 and P <(5/4) × S
Rotating electric machine characterized by that. In a rotating electrical machine comprising a rotor having P magnetic poles arranged in a circumferential manner at approximately equal intervals, and a stator having S slots arranged in a circumferential manner at substantially equal intervals,
The relationship between the number P of the magnetic poles and the number S of the slots is
P ≦ S-4 and P> (3/4) × S
Rotating electric machine characterized by that.   The rotating electrical machine according to claim 1, wherein the number of drive phases to the stator is 5 or more.   The rotating electrical machine according to claim 3, wherein the number of drive phases is N or 2N (where N is an odd number equal to or greater than 7).   The rotating electrical machine according to claim 4, wherein the number S of slots is a multiple of the number N of driving phases. (N or 2N, S, P), which is the relationship between the number N of driving phases, the number S of slots, and the number P of magnetic poles,
(9, 27, 32), (9, 27, 22), (18, 27, 32), (18, 27, 22), (18, 36, 42), (18, 36, 30), (18 36, 44) or (18, 36, 28). The rotating electrical machine according to claim 4 or 5.   The rotating electrical machine according to any one of claims 1 to 6, wherein the rotating electrical machine is a disk-type motor in which the rotor and the stator are arranged to face each other in the rotor rotation axis direction.

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