JP4468740B2 - motor - Google Patents

Description

  The present invention relates to a motor, and more particularly to a motor that can be suitably applied to an electric vehicle (PEV), a hybrid vehicle (HEV), a fuel cell vehicle (FCEV), and the like, and can also be suitably applied to home appliances and robots. .

  Conventionally, a concentrated winding embedded magnet type motor has been known as a motor used in the above-described automobiles or the like (for example, see Patent Document 1).

  The configuration of the motor will be described with reference to FIG. FIG. 7 is a cross-sectional view of the main part of the motor, taken along a plane perpendicular to the rotation center axis of the motor. In FIG. 7, a stator 11 is configured by winding a winding 3 around a plurality (12 in the illustrated example) of salient poles 2 provided at equal intervals on the inner peripheral portion of the stator core 1. A plurality of (eight in the illustrated example) permanent magnets 5 are arranged on the rotor core 4 in the circumferential direction so that the outer peripheral surface is opposed to the inner peripheral surface of the salient pole 2 of the stator 11 with a minute gap. A rotor 12 embedded in an interval is rotatably disposed. Each of the windings 3 constitutes a U-phase, a V-phase, and a W-phase, and each phase winding 3 is supplied with, for example, a trapezoidal wave-like current whose phase is shifted by 120 (deg) in electrical angle. Then, the torque generated between the winding 3 of each phase and the rotor core 4 is generated with a phase shift of 120 (deg). The total torque is a combination of the three-phase generated torque, and the rotor core 4 rotates in a predetermined direction. That is, a so-called three-phase full-wave drive rotation operation that rotates around the rotation center axis is performed.

In addition, a plurality of (for example, nine) salient poles provided on the stator are grouped into a plurality of (for example, three) salient poles that are adjacent to each other and to which an in-phase voltage is applied. 3) and apply U-phase, V-phase, and W-phase voltages to each group, and the windings for the salient poles adjacent to each other in each group have the winding direction. The permanent magnets that are opposite to each other and that have fewer permanent magnets than the number of salient poles are arranged at equal intervals, and the salient poles are arranged at irregular intervals, so that the center line of the salient pole and the pole center of the permanent magnet are There is also known one in which the positional deviation is reduced and the phase deviation of the induced voltage of the winding is reduced (for example, see Patent Document 2).
JP 2000-245085 A JP 2002-199630 A

  By the way, the concentrated winding motor as disclosed in Japanese Patent Application Laid-Open No. 2000-245085 has an advantage that the torque can be increased. On the other hand, waveform distortion is recognized in the counter electromotive voltage, and waveform distortion of the counter electromotive voltage is large. There is a problem that eddy current increases, iron loss increases, and efficiency decreases. There is also a problem that eddy currents are also generated in the permanent magnet 5 embedded in the rotor 12, and the permanent magnet 5 generates heat, causing a temperature rise and demagnetization.

  Further, the motor disclosed in Japanese Patent Laid-Open No. 2002-199630 is a motor having an 8-pole / 9-slot configuration, and has a larger number of salient poles than the number of permanent magnets as in the conventional motor shown in FIG. It is a configuration. In such a configuration, the circumferential dimension of the tip of the salient pole is smaller than the effective width in the circumferential direction of the permanent magnet, and the stator winding is concentrated winding, so that the induced voltage waveform is distorted, There is a problem that the controllability deteriorates, and the peak of the distorted waveform rises sharply and sharply as the rotation speed increases, and the peak voltage exceeds the allowable voltage, so high speed rotation is impossible due to voltage limitation There is also a problem.

  The present invention has been made in view of the above-described conventional problems, and an object of the present invention is to provide a motor that can be optimized according to demands for controllability and characteristics with respect to cogging torque, with high torque and less distortion of the induced voltage waveform. And

The motor of the present invention includes a stator in which a winding is wound around each of a plurality of salient poles provided on a stator core, and a rotor in which a larger number of permanent magnets are arranged on the rotor core at equal intervals in the circumferential direction than the number of salient poles. A plurality of salient poles in which windings to which in-phase voltage is applied are wound and adjacent to each other, and winding directions of adjacent salient pole windings are opposite to each other. The number of salient poles is composed of a plurality of salient pole groups, and the total number of salient poles is T, the total number of permanent magnets is P, and the salient pole arrangement angle θs (deg) in each salient pole group is 360 / P ( deg) ≦ θs (deg) ≦ 360 / T (deg), and within each of the plurality of salient pole groups, the salient pole arrangement angle θs (deg) is the permanent magnet arrangement angle ( 360 / P (deg)) and 360 / P (deg) <θ In the case of (deg) ≦ 360 / T (deg), each salient pole in each salient pole group is eliminated so as to eliminate the magnetic flux density difference due to the phase difference between each salient pole in each salient pole group. The cross-sectional area of the poles is reduced in order from the rear side in the rotational direction of the rotor to the front side in the rotational direction .

  According to this configuration, by configuring the concentrated winding permanent magnet type motor, high torque can be generated, and in each salient pole group, the windings are arranged so that adjacent salient poles have different polarities. Since the wire is wound, it is possible to alleviate the uneven distribution of the magnetic field distribution, reduce the distortion of the back electromotive voltage waveform induced in the winding when the motor is driven, and reduce the iron loss in the stator core and the rotor core. Occurrence can be suppressed. In addition, since the generation of eddy currents can be suppressed for the permanent magnets in the rotor core, the generation of heat can be reduced, demagnetization of the permanent magnets can be suppressed, and an efficient motor can be realized. The salient poles in each salient pole group are arranged at the same angle around the stator core, and the angle of the salient poles and permanent magnets matching the permanent magnets, so that the phases of the salient poles and the permanent magnets are the same. By setting a desired angle between the angle and the angle at which the cogging torque can be minimized, a motor according to the required controllability and cogging torque characteristics can be obtained.

  Further, when the salient pole arrangement angle is not 360 / P (deg), the salient pole winding is made uniform by eliminating the magnetic flux density difference due to the phase difference between the salient poles adjacent to each other in the same phase. If the cross-sectional area of the winding part is changed, the magnetic flux density becomes uniform between the salient poles, the induced voltage becomes constant and controllability is improved. The wire diameter can be increased, the copper loss can be reduced, and the efficiency can be improved.

  According to the motor of the present invention, the concentrated winding permanent magnet type motor is configured so that high torque can be generated and adjacent salient poles have different polarities in each salient pole group. Since the winding is wound, the uneven magnetic field distribution can be alleviated, and the distortion of the back electromotive voltage waveform induced in the winding when the motor is driven can be reduced. Furthermore, the salient pole placement angle in each salient pole group matches the permanent magnet placement angle so that the salient pole and permanent magnet phases match, and high controllability is obtained. By setting the desired angle between the angle at which the cogging torque can be minimized in accordance with the angle when they are equally arranged, a motor corresponding to the required controllability and cogging torque characteristics can be obtained.

  In addition, when the salient pole arrangement angle in each salient pole group is not the same as the angle when the salient poles are evenly distributed around the entire circumference of the stator core, adjacent salients across the open slots between the salient pole groups. In addition to being able to reduce the cogging torque by relaxing the permeance change of the magnetic path of the magnetic flux coming out of the permanent magnet, and suppressing the occurrence of iron loss in the stator core and the rotor core, since the tip portions of the poles are stretched respectively. Since generation of eddy current in the permanent magnet of the rotor core can be suppressed to reduce heat generation and demagnetization of the permanent magnet can be suppressed, an efficient motor with reduced cogging torque can be obtained.

  Hereinafter, embodiments of the motor of the present invention will be described with reference to the drawings.

(First reference form)
A first reference embodiment of the motor of the present invention will be described with reference to FIGS. 1 and 2, for illustrating the motor structure of this preferred embodiment, is a main part cross-sectional view taken on a plane perpendicular to the central axis of rotation of the motor. 1 and 2, a stator core 1 configured by laminating electromagnetic steel plates has a plurality of salient poles 2, and windings 3 are wound around the salient poles 2. The winding 3 is configured as a three-phase winding, and each phase includes three windings 3 in the illustrated example. The three windings 3 having the same phase are arranged at continuous positions, and the middle winding 3 is wound around the windings 3 adjacent to each other so that the winding directions are opposite to each other. The three windings 3 thus wound are connected in series or in parallel, and the winding groups of each phase are arranged with a phase difference of 120 (deg) in electrical angle. In this manner, the group of salient poles 2 around which the in-phase windings 3 are wound constitute salient pole groups I, II, and III, respectively. That is, three salient pole groups I, II, and III are disposed at an electrical angle of 120 (deg) corresponding to the three-phase winding. In the case of a three-phase winding, the salient pole groups are arranged at an electrical angle of 120 (deg) with three multiples.

  On the other hand, a rotor 12 is configured by embedding and arranging a plurality of permanent magnets 5 at equal intervals in a rotor core 4 formed by laminating electromagnetic steel plates, and the salient poles 2 are freely rotatable around a rotation center O. It arrange | positions through a slight gap between the inner peripheral surfaces.

  As shown in FIG. 1, the arrangement angle θs (deg) of the salient pole 2 in each salient pole group I, II, III is permanent, with the number of poles of the permanent magnet 5 being P and the total number of salient poles 2 being T. An arbitrary angle between 360 / P (deg) that coincides with the arrangement angle θmg (deg) of the magnet 5 and an angle 360 / T (deg) when the salient poles 2 are equally arranged over the entire circumference of the stator core 1 Can be set. 1 shows a state in which the arrangement angle θs (deg) of the salient pole 2 is set to 360 / P (deg) equal to the arrangement angle θmg (deg) of the permanent magnet 5, and the illustration example of FIG. The arrangement angle θs (deg) of the salient poles 2 is shown as 360 / T (deg) in which the salient poles 2 are evenly distributed over the entire circumference of the stator core 1.

  In the illustrated example of FIGS. 1 and 2, one set of three-phase windings of U, V, and W in the stator 11 is set as one set, the number of winding sets is 1, and the number of slots per one-phase winding is three (3 For example, a motor having 9 slots and 10 permanent magnets constituting the rotor, that is, a 10-pole motor is illustrated. However, the present invention can be applied to such a 3-fork / winding group number 1 · 9 slot · 10-pole motor. It is not limited.

The motor of the present invention can be an n-fork, winding set number s, T slot, and P pole motor. In this case, n and s are both positive integers, the number of slots T is (n × s), the number of rotor poles P is an even number larger than the number of slots T, and the following expression P = 2 × (s (± 1 + 3k)) (where k = positive integer)
Is defined as a value satisfying Furthermore, it is preferable to set P to the minimum value larger than T (P> T) because the volumetric efficiency becomes high.

  The number of poles is determined using this relational expression. Specific examples include those shown in Table 1.

上式は、各突極グループの巻線３に電流を順次Ｕ、Ｖ、Ｗと流したときにスムーズに回転する条件によって規定されるものである。すなわち、磁石の極対数をＰ／２とすると、ロータが回転することによって磁石より誘起される誘起電圧波形Ｂｅは、
Ｂｅ＝ｓｉｎ（ｐ／２×θ）
と表すことができる。ここで、３相モータなので、Ｕ、Ｖ、Ｗは電気角で１２０（ｄｅｇ）づつずれている。そこで、電気角で１２０（ｄｅｇ）ずらして各相巻線に通電したときに、ロータが同じ角度で同じ方向に回転すればよいことになる。したがって、次の式
ｓｉｎ（ｐ／２×（θ＋１２０／ｓ））
＝ｓｉｎ（ｐ／２×θ±１２０＋３６０ｋ）
が成立すればよいことになる。

The above equation is defined by the condition of smoothly rotating when currents are sequentially passed through the windings 3 of each salient pole group as U, V, and W. That is, when the number of pole pairs of the magnet is P / 2, the induced voltage waveform Be induced from the magnet by the rotation of the rotor is
Be = sin (p / 2 × θ)
It can be expressed as. Here, since it is a three-phase motor, U, V, and W are shifted by 120 (deg) in electrical angle. Therefore, when the respective phase windings are energized with an electrical angle shifted by 120 (deg), the rotor only needs to rotate at the same angle and in the same direction. Therefore, the following formula sin (p / 2 × (θ + 120 / s))
= Sin (p / 2 × θ ± 120 + 360k)
It will be sufficient if is established.

  When the induced voltage waveform (rotor) is at a position deviated by 120 (deg) in electrical angle from Be = 0 at a certain time (expression is a mechanical angle), 120 ( deg) (shift of U, V, W) If the position is the same as the shifted position, the rotor position (induced voltage waveform Be) can be applied even if power is supplied at a position shifted 120 (deg) from V to V and V to W sequentially. Always shows the same electrical value and indicates that it can make one rotation smoothly.

The rotor 12 of this preferred embodiment is constituted by a rotor core 4 and a plurality of substantially V-shaped permanent magnet 5 embedded at equal intervals in the circumferential direction in the rotor core 4, the stator facing surfaces of the rotor 12 of the stator 11 The rotor is opposed to the rotor facing surface with a minute gap, and is rotatable around the rotation axis O. Therefore, the embedded permanent magnet 5 forms a portion where the magnetic flux is relatively easy to pass and a portion where the magnetic flux is relatively difficult to pass in the stator facing portion of the rotor 12, that is, a portion having a low magnetic resistance and a magnetic resistance lower than that. As a result, the difference between the inductance in the q-axis direction and the inductance in the d-axis direction can be generated, reluctance torque can be generated, and the generated torque can be increased.

  Further, since P> T as described above, the arrangement angle of the permanent magnet 5 is smaller than the average arrangement angle of the salient poles 2, so that the effective width in the circumferential direction of the permanent magnet 5 is d1, as shown in FIG. The circumferential width of the tip of the salient pole 2 can be set as d2, and d1 ≦ d2 can be set. Thereby, since the whole permanent magnet 5 always overlaps with the tip of the salient pole 2, the induced voltage waveform becomes a sine wave, which can prevent waveform distortion of the induced voltage and improve the controllability of the voltage.

  According to the motor having the above configuration, the concentrated winding permanent magnet type motor is configured so that high torque can be generated, and adjacent salient poles 2 in each salient pole group I, II, III. 2 is wound so that the polarities are different from each other, the magnetic field distribution can be relaxed, and the waveform of the back electromotive voltage induced in the winding 3 when the motor is driven can be reduced. It is possible to reduce the occurrence of iron loss in the stator core 1 and the rotor core 4. In addition, since the generation of eddy current is suppressed for the permanent magnet 5 in the rotor core 4, the heat generation caused thereby is reduced, the demagnetization of the permanent magnet can be suppressed, and an efficient motor can be realized. .

  Further, in the motor having the above configuration, when the arrangement angle θs (deg) of the salient poles 2 in each salient pole group is made to coincide with the arrangement angle θmg (= 360 / P (deg)) of the permanent magnet 5, the salient poles 2. The phase of the permanent magnet 5 coincides with that of the permanent magnet 5 and high controllability is obtained. On the other hand, the arrangement angle θs (deg) of the salient pole 2 is equal to the angle (= 360 / T) when the salient pole 2 is evenly distributed over the entire circumference of the stator core 1. (Deg)), the cogging torque can be minimized. Therefore, the arrangement angle θs (deg) of the salient poles 2 is arbitrarily set between 360 / P (deg) and 360 / T (deg) according to the required controllability and cogging torque characteristics. A motor having the following characteristics can be obtained.

(Second reference form)
Next, the motor of the second referential embodiment of the present invention with reference to FIG. In the following description of the reference embodiment, the same components and reference embodiment the preceding are denoted by the same reference numerals to omit the description, different points are mainly described.

In FIG. 3, in this reference embodiment, the arrangement angle of the salient poles 2 in each salient pole group I, II, III is not 360 / T (deg), that is, 360 / P (deg) ≦ θs (deg) <360. / T (deg), the open slot angle os1 (deg) between the salient poles 2 and 2 in each salient pole group I, II, III is related to the arrangement angle θs (deg) of the salient pole 2 ,
θs / 5 (deg)> os1 ≧ θs / 7 (deg)
And the open slot angle os2 (deg) between the salient poles 2 and 2 between the salient pole groups I, II and III is set to the salient pole 2 adjacent between the salient pole groups I, II and III, By adjusting the length of each leg 6
os2 (deg) ≦ os1 (deg)
Is set to satisfy.

With this configuration, the arrangement angle θs (deg) of the salient poles 2 in the salient pole groups I, II, and III is equal to the arrangement angle θmg (deg) of the permanent magnet 5 and between the salient pole groups I, II, and III. The open slot angle os2 (deg) between the salient poles 2 and 2 is set to be equal to or smaller than the open slot angle os1 (deg) between the salient poles 2 and 2 in the salient pole groups I, II and III. Since the permeance change of the magnetic path of the magnetic flux emitted from the permanent magnet 5 can be relaxed and the change of magnetic field energy can be relaxed, the cogging torque can be reduced while maintaining high controllability. That is, in the case where the legs 6 of the salient poles 2 between the salient pole groups I, II, and III are not stretched, the arrangement angle θs (deg) of the salient poles 2 in the salient pole groups I, II, and III is set as the permanent magnet 5. Is equal to the arrangement angle θmg (deg) of the rotor, a gap is generated between the salient poles 2 and 2 between the salient pole groups I, II, and III, and the open slot angle os2 (deg) between them becomes larger. When the magnet 12 rotates and the permanent magnet 5 passes through the open slot angle os2 (deg), the permeance change of the magnetic path increases and the cogging torque increases. However, the cogging torque is configured as described above. Can be reduced.

  Furthermore, the arrangement angle θs (deg) of the salient poles 2 in the salient pole groups I, II, and III is any angle between the arrangement angle θmg (deg) of the permanent magnet 5 and 360 / T (deg). In addition, at the tips of all the salient poles 2 over the entire circumference of the stator 1, the legs of the tips of the salient poles 2 are arranged so that the arrangement interval is 360 / T (deg), where T is the total number of salient poles. 6 may be adjusted. In this case, the length of the foot 6 at the distal end may be longer, while the length may be shorter. With this configuration, the cogging torque can be further reduced.

(Implementation form)
Next, the motor of the implementation form of the present invention with reference to FIG.

  In FIG. 4, in this embodiment, in each of the salient pole groups I, II, and III, the arrangement angle θs (deg) of the salient pole 2 matches the arrangement angle of the permanent magnet 5 (360 / P (deg)). In the case of 360 / P (deg) <θs (deg) ≦ 360 / T (deg), the magnetic flux density due to the phase difference between the salient poles 2 and 2 in each salient pole group I, II, III In order to eliminate the difference, the sectional area of the winding portion of the winding 3 of each salient pole 2 is located on the front side with respect to the sectional area w1 of the salient pole 1 located on the rear side in the rotation direction of the rotor 12. The cross-sectional area w2 of the salient pole 2 is reduced, and the cross-sectional area w3 of the salient pole 2 located further forward is further reduced.

  With this configuration, the magnetic flux density of each salient pole 2 in each salient pole group I, II, III is made uniform, and the induced voltage generated in the winding 3 wound around each salient pole 2 is made constant. Therefore, controllability is improved. Further, in the salient pole 2 having a reduced cross-sectional area, the winding diameter of the winding 3 can be increased, and the copper loss can be reduced accordingly, and the efficiency can be improved.

( Third reference form )
Next, a motor according to a third embodiment of the present invention will be described with reference to FIG.

5, in this preferred embodiment, each salient pole groups I, II, in III, in the case where the stator teeth 2 disposed angle [theta] s (deg) does not match the permanent magnet 5 disposed angle 360 / P (deg) The salient pole 2 is provided with a skew of an arbitrary angle between 360 / P (deg). In the illustrated example, a skew of an angle β is provided such that the arrangement angle of one end of the salient pole 2 is 360 / T (deg) and the arrangement angle of the other end is 360 / P (deg). Of course, the skew angle can be set to any angle between 0 and β.

  Thus, by providing the salient pole 2 with a skew having an arbitrary angle up to 360 / P (deg), the influence of the phase shift between the salient pole 2 and the permanent magnet 5 can be reduced, and the cogging torque can be reduced. While achieving reduction, controllability at a particularly high speed can be improved.

( 4th reference form )
Next, a motor according to a fourth embodiment of the present invention will be described with reference to FIG.

In the above-described reference embodiment, an example in which the rotor 12 includes only a magnet-type rotor in which a permanent magnet is embedded in the rotor core 4 is shown. However, in this reference embodiment, a magnet-type rotor portion 7 in which the permanent magnet 5 is embedded in the rotor core 4 and FIG. 6 (b), a reluctance type rotor 8 in which recesses 10a are formed at equal intervals on the outer periphery of the rotor core 9 to form the same number of salient poles 10 as the permanent magnet 5 is shown in FIG. 6 (a). As shown, the rotor 12 is configured by being laminated in the axial direction.

  According to this configuration, the reluctance torque can be used more and thereby the following effects can be obtained. That is, if the cogging torque characteristic is given priority over the controllability by not setting the arrangement angle of the salient poles 2 of the stator 11 to 360 / P (deg), the controllability particularly during high-speed rotation deteriorates. By using reluctance torque, controllability can be improved, cogging torque characteristics are good, and high controllability can be ensured even at high speeds.

Although not illustrated, in the above-described embodiment, when the sub-groove is provided on the surface of the salient pole tip surface facing the rotor, the polarity at the tip of the salient pole apparently becomes the S pole, N pole, Since it is subdivided into the S poles, high torque can be generated and at the same time torque ripple can be kept small, and cogging torque can be further reduced. The shape of the sub-groove at that time is not limited to a rectangular shape, and may be an arc shape. In addition, one sub-groove is not necessarily formed for one salient pole, but a plurality of sub-grooves can be formed for one salient pole.

  Further, in the above-described embodiment, when the cut-away portion is provided on the surface facing the rotor at the tip portion of the salient pole so as to be separated from the stator facing surface of the rotor core in the vicinity of the circumferential end portion, The change in magnetic field energy can be further relaxed, and the cogging torque can be further reduced.

  Further, in the above-described embodiment, the rotor core is provided with a slit having a shape substantially the same as that of the permanent magnet and having a width smaller than the thickness of the permanent magnet on the side opposite to the stator side from the position of the permanent magnet. With the rotor structure as described above, more reluctance torque can be used.

  In the above description of the embodiment, the inner rotor type motor in which the rotor 12 is rotatably disposed inside the stator 11 is exemplified. However, the motor of the present invention has an annular rotor rotatably disposed on the outer periphery of the stator. It is obvious that it can be applied to the provided outer rotor type motor and has the same operational effects, without needing to be described again.

Also, more motors of implementation of the invention is, or PEV (pure electric vehicle), HEV (hybrid electric vehicle), by using as an electric vehicle drive motor such FCEV (fuel cell electric vehicle), the drive The motor is smaller and more efficient, quieter and better in controllability. An electric vehicle equipped with this motor has a wider cabin, longer charging distance, and lower vibration and noise when starting. An automobile can be realized. Moreover, the same effect is exhibited when the motor is used as a drive motor provided in a home appliance, a robot, or the like.

Since the motor of the present invention can be designed according to characteristics required for controllability and cogging torque characteristics with a simple configuration and small size and high efficiency, PEV (pure electric vehicle) and HEV (HEV (
It is useful as a motor for driving an electric vehicle such as a hybrid electric vehicle (FCEV) or a fuel cell electric vehicle (FCEV), a driving motor provided in a home appliance, a robot, or the like.

It is sectional drawing which shows schematic structure of the motor of the 1st reference form of this invention. It is sectional drawing which shows schematic structure of the other aspect of the motor of the reference form. It is sectional drawing which shows schematic structure of the motor of the 2nd reference form of this invention. It is an enlarged sectional view of the motor of the implementation of the invention. It is explanatory drawing of the state which formed the skew in the salient pole in the motor of the 3rd reference form of this invention. The motor of the 4th reference form of this invention is shown, (a) is a fragmentary perspective view of the principal part, (b) is a top view of a reluctance type | mold rotor part. It is sectional drawing which shows schematic structure of the principal part of the motor of a prior art example.

DESCRIPTION OF SYMBOLS 1 Stator core 2 Salient pole 3 Winding 4 Rotor core 5 Permanent magnet 7 Magnet type rotor part 8 Reluctance type rotor part 9 Rotor core 10 Salient pole 11 Stator 12 Rotor I, II, III Salient pole group

Claims (1)

A stator in which a winding is wound around each of a plurality of salient poles provided on the stator core, and a rotor on which a number of permanent magnets are arranged at equal intervals in the circumferential direction on the rotor core. A plurality of salient poles are composed of a plurality of salient poles wound with windings to which a voltage of the same phase is applied and adjacent to each other and winding directions of adjacent salient pole windings are opposite to each other. The number of salient poles is T, the total number of permanent magnets is P, and the salient pole arrangement angle θs (deg) in each salient pole group is defined as:
360 / P (deg) ≦ θs (deg) ≦ 360 / T (deg)
Set to any angle that meets the
Within each of the plurality of salient pole groups, the salient pole arrangement angle θs (deg) does not coincide with the permanent magnet arrangement angle (360 / P (deg)), and 360 / P (deg) <θs (deg). In the case of ≦ 360 / T (deg), the break of each salient pole in each salient pole group so as to eliminate the magnetic flux density difference due to the phase difference between each salient pole in each salient pole group. The motor has a smaller area in order from the rear side in the rotational direction of the rotor to the front side in the rotational direction .

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