WO2005091467A1

WO2005091467A1 - Brushless motor

Info

Publication number: WO2005091467A1
Application number: PCT/JP2005/005598
Authority: WO
Inventors: Hiroyasu Fujinaka
Original assignee: Matsushita Electric Industrial Co., Ltd.
Priority date: 2004-03-19
Filing date: 2005-03-18
Publication date: 2005-09-29

Abstract

A brushless motor, comprising a rotor (6) having a magnet body (1) with magnetic poles of 2m in quantity to which N-pole and S-pole are alternately magnetized in the rotating direction and a core (3) radially opposed to the magnet body and having a salient pole section (4) with salient poles of 3n in quantity around which a coil is wrapped. In the magnet body, the magnetic flux generating part of each pole is reduced by an electrical angle α less than a magnetic pole pitch and the open angle θ of the salient pole is set to a specified electrical angle. Thus, the cogging torque of the brushless motor can be reduced, and the rotating accuracy thereof can be increased.

Description

Specification

Brushless motor technical field

The present invention relates to a brushless motor used as a drive source of a device. Background art

At present, various equipment such as video / audio equipment and 映像 A equipment are used as drive sources. In particular, as the storage density of devices such as optical disk devices and magnetic disk storage devices increases, it is desired that the motors of the same size have higher rotational accuracy.

A factor that deteriorates the rotation accuracy of the motor is a cogging torque generated by a change in the magnetic attraction force between the motor core and the magnet. Various proposals have been made for a method of reducing the cogging torque. For example, it is disclosed in Japanese Patent Application Laid-Open Publication No. 2001-168806.

FIGS. 15A, 15B, and 15C are diagrams showing a magnetic circuit of a conventional motor. The core 30 has six salient poles 40 at the tip. An outline of the conventional cogging torque reduction technology of the conventional example will be described. In this conventional mode, the cogging torque period generated by adjusting the core slot opening angle λ was set to half of the basic cogging torque period, and then shifted by a predetermined angle based on this shape. It is configured to combine core shapes. This proposes a technology that makes the cycle of the cogging torque less than one-fourth of the cycle of the basic cogging torque and greatly reduces the absolute value of the cogging torque.

However, in the case of the configuration of the conventional example, a sufficient cogging torque reduction effect may not be obtained when a field having a special configuration is used. Disclosure of the invention

The brushless motor of the present invention has the following configuration.

A mouth with a magnet body with 2 m of magnetic poles alternately magnetized with N poles and S poles in the rotation direction — evening and 3 n salient poles with coils wound around the magnet body in the radial direction A brushless motor having a core provided with poles, wherein a magnet body has a difference between a magnetic flux generating portion of each pole and a magnetic pole pitch equal to an electrical angle, and an open angle of a salient pole is defined as an electrical angle of 0. ). However, h in (Equation 1) is the least common multiple of 2 m and 3 n, and k is a natural number.

Furthermore, the present invention also includes a configuration in which the difference (electric angle) between the magnetic flux generating portion of each pole and the magnetic pole pitch is substantially zero. c,,-α + 5 (Equation 1)

With this configuration, it is possible to obtain a special effect that the cogging torque of the motor can be reduced and the rotational accuracy of the motor can be improved. Brief Description of Drawings

FIG. 1 is an explanatory diagram showing a magnetic circuit configuration of a brushless motor according to a first embodiment of the present invention.

FIG. 2 is a diagram showing the relationship between the salient pole opening angle and the cogging torque in the first embodiment of the present invention.

FIG. 3 is an explanatory diagram showing the principle of generating cogging torque at salient poles according to the first embodiment of the present invention.

Fig. 4Α is a waveform diagram of the cogging torque in the first embodiment of the present invention (a waveform diagram of the torque generated at the front salient pole edge 5-1). FIG. 4B is a waveform diagram of the cogging torque according to the first embodiment of the present invention (a waveform diagram of the torque generated in the rear salient pole edge portion 5-2).

FIG. 4C is a waveform diagram of the cogging torque according to the first embodiment of the present invention (a waveform diagram of the combined torque of FIGS. 4A and 4B).

FIG. 4D is a waveform diagram of cogging torque according to the first embodiment of the present invention (a waveform diagram of three-phase combined torque).

FIG. 5A is an explanatory view showing a core shape of another brushless motor according to the first embodiment of the present invention (when R is provided at the tip of the salient pole).

FIG. 5B is an explanatory view showing a core shape of another brushless motor according to the first embodiment of the present invention (when a chamfer is provided at the tip of the salient pole).

FIG. 5C is an explanatory view showing a core shape of another brushless model according to the first embodiment of the present invention (when a fillet is provided at a salient pole tip edge).

FIG. 6 is a configuration diagram of a magnetic circuit of another brushless motor according to the first embodiment of the present invention.

FIG. 7 is a configuration diagram of a magnetic circuit of another brushless motor according to the first embodiment of the present invention.

FIG. 8 is a configuration of a magnetic circuit of a brushless motor according to a second embodiment of the present invention.

FIG. 9 shows a configuration of a magnetic circuit of a brushless motor according to a third embodiment of the present invention.

FIGS. 10A and 10B are explanatory diagrams of a core shape configuration method according to the third embodiment of the present invention.

FIG. 11 is an explanatory diagram showing another core shape according to the third embodiment of the present invention. FIGS. 12A and 12B are explanatory diagrams of a core shape configuration method according to the third embodiment of the present invention. FIG. 13 is an explanatory diagram showing another core shape according to the third embodiment of the present invention. FIGS. 14A and 14B are explanatory diagrams of a core shape configuration method according to the third embodiment of the present invention.

15A, 15B, and 15C are explanatory diagrams of a conventional example.

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

(First Embodiment)

FIG. 1 is an explanatory diagram showing a magnetic circuit configuration of a brushless motor according to the first embodiment. As shown in Fig. 1, the magnet body 1 has a plurality of permanent magnets with an electrical angle smaller than the magnetic pole pitch (electrical angle 180 °) fixed to the inner periphery of the annular back yoke 2 by a fixed width. Is composed. In addition, in the stay 7, a coil (not shown) is wound around the teeth of the core 3, and the teeth have salient poles 4 at the tips. The following description of angles is based on electrical angles. The angle in the drawing is also an electrical angle. In FIG. 1, the opening angle of the tip of the salient pole 4 of the core 3 is represented by the following electrical angle. Here, FIG. 1 illustrates the case where α = 40 °.

FIG. 2 is a diagram showing a change in cogging torque when the opening angle の of the salient pole tip in FIG. 1 is changed. In FIG. 2, the cogging torque is minimal near the electrical angles of 110 ° and 170 °. Also, at around 130 ° and 190 °, a "convex" wave appears at "F."

In the prior art shown in FIG. 15 Α, it is shown that the cogging torque is minimized when the salient poles 40 are around 90 °, 150 °, and 210 °. In the case of a magnet body with a special configuration in which the magnetic poles are partially interrupted, the point at which the cogging torque is minimized greatly differs.

The following is the reason for this, and even with such a specially structured magnet body, A method for reducing the cogging torque will be specifically described.

Multipole magnetized magnet body in normal configuration: magnetic pole switching part from N pole (S pole) to S pole (N pole) = rising part of magnetic flux of S pole (N pole) = N pole (S pole) However, if a gap is provided between the magnetic poles as in the present embodiment, the rising portion of the magnetic flux of the S pole (N pole) ≠ the magnetic pole of the N pole (S pole) The configuration has a falling part, and it is necessary to consider both separately.

Here, in order to explain the mechanism of cogging torque generation, the cogging torque generated at one salient pole 4, which is the maximum J, is considered.

FIG. 3 is a diagram illustrating the principle of generating cogging torque at salient poles. In FIG. 3, first, consider a case where a magnetic pole switching portion approaches the front edge portion 4 _ 1 of the salient pole 4. FIG. 4A is an explanatory diagram of the cogging torque generated in the salient-pole front edge portion 411. In Fig. 3, the point where the falling part 5-1 of the magnetic pole and the front edge part 4_1 of the salient pole match is considered as a reference. In FIG. 3, when the falling part 5-1 of the magnetic pole passes through the leading edge 4-1 of the salient pole, the cogging torque becomes almost zero, and as shown in FIG. The waveform has a periodicity.

FIG. 4B is an explanatory diagram of the cogging torque similarly generated at the salient pole rear edge portion 4-2. Here, comparing the torque waveform of Fig. 4A and the torque waveform of Fig. 4B, the cogging torque generated at the rear edge 4_2 of the salient pole is expressed by Considering the time when part 5-1 passes as a reference, it is point-symmetric with the cogging torque generated at the ij edge 4_1 before the salient pole, and the reference point has a waveform shifted by θ + α. I understand that there is.

From the above, the cogging torque generated at the salient pole front side wedge 4-1 and the cogging torque generated after the salient pole ij wedge 4-2 have regularity, and if the opening angle の of this salient pole 4 is adjusted, It can be imagined that a specific component of the cogging torque can be removed.

Figure 4C shows the cogging torque generated by one salient pole 4 that combines Figure 4A and Figure 4B. FIG.

Here, if the rotation angle is expressed as X in electrical angle based on the time when the falling edge 5-1 of the magnetic pole passes through the salient pole front edge 4-1, the torque generated at the salient pole front edge 4_1 The waveform can be expressed as (Equation 2). a X sin (2x) + DX sini "4x) + cx sm (6x) + dx sm (8x) + ex sm (10x) + / x sm (2; ^

(Equation 2) Further, the torque waveform generated at the rear edge 412 of the salient pole can be expressed as the following (Equation 3).

-ax sin (-2x + 2 (θ + a))-bx sini— 4x + 4 (θ + a)) -ex sin (-6x + 6 (θ + a)) -dx sin (-8 + 8 ( ^ + a))-ex sin (-10x + 10 (θ + a))-fx sin (-12 ^ + 12 (θ + a))

(Equation 3) Here, the combined waveform of both the cogging torque waveforms at one salient pole 4 is ((Equation 2) + (Equation 3)). a X CsinC2x) + sin (2x-2 (θ + a)) + b (sin (4x) + sm (4x-4 (θ + a))

+ cx (sin (bx + sin (6x-6 (6 * +))) + dx (sin (8x) + sin (8x-8 (^ + a))

+ ex (sin (10x) + sin (10-1 (θ + α) / 2) + / χ (sin (12x) + sin (12x-1 12 (θ + a))

(Equation 4)

Here, when 0 + α is set to a specific value, a specific component can be removed. Specifically, Θ + α is 90 °, 150. , 2 1 0 ° (in other words, 0 = 90 0-α, θ = 16 0-, 0 = 2 1 0-0;), the third-order component (sin ( 6 x)) is the removed torque.

FIG. 4D shows the cogging torque waveform as a whole.

Since this motor has a three-phase structure, among the torques shown in Fig. 4C, the primary, secondary, quaternary, quintic, and cubic torques are omitted. At 120 °, the torque is canceled by the other two-phase torque. Next, 6th order. · · (Not shown) · · '' torque appears, so 0 = 90

—Hi, 0 = 1 5 0— α, θ = 2 1 0— «If any of these can be used to suppress the third-order component of the torque generated per salient pole, the key that appears as a whole The period of the oscillating torque is half of the normal one, and its amplitude is small.

Also, the above embodiment has shown that the cogging torque is minimized when the salient pole opening angle 0 is 150-α, but considering that the angle fluctuates to some extent from 150-0-0; If the salient pole opening angle is reduced to an electrical angle of 140-0; or 1-60, the third-order component of the cogging torque generated at the salient pole is removed by 50%, and the salient pole opening angle is reduced to an electrical angle of 145 — Or 1 5 5—In this case, the third-order component of the cogging torque generated at the salient pole is removed by 74%. To obtain practical performance, the cogging torque generated at the salient pole is reduced to 3%. By setting the next component to less than about one-fourth, that is, 14 5-α to 15 5 -α, the fundamental period component of the cogging torque is greatly reduced, and the cogging torque can be reduced.

In addition, when the shape of the tip of the salient pole 4 is formed with an R portion 4a smaller than the core radius as shown in Fig. 5Α, or when a chamfered portion 4b is provided as shown in Fig. 5B, or Fig. 5C When the fillet portion 4c is provided at the edge portion as shown in Fig. 4 or when the effect of magnetic saturation of the core is taken into account, the magnetic characteristics are close to the condition where the opening angle of the salient pole 4 is small. When the opening angle 0 of the salient pole 4 is slightly large (around 5 ° in electrical angle), the phenomenon that the cogging torque is minimized may occur.

Therefore, in general, the surface of the magnet body is configured to generate a magnetic flux in a range (180-0;) having a real electric angle narrower than the magnetic pole pitch (electric angle: 180 °), and is provided on the salient pole. The open angle 0 of the salient pole is the electrical angle, which is one of the following: 8 5-α <θ <1 0 0-, 145—a <θ <6 20 5—a <S <2 2 0—o; By setting the value in the range that satisfies the above condition, a cogging torque having a cycle that is one half of the basic cogging torque cycle is generated, and a motor with a small absolute value of the cogging torque can be provided. Note that the above discussion was based on the time when the falling edge 5-1 of the magnetic pole passes through the front edge portion 4-1. Similarly, the time when the rising portion 5-2 of the magnetic pole passes through the front edge portion 4-1. When the reference is used as a reference, the salient-pole front edge 4-1 and the salient-pole rear edge 4-2 can be considered to be point-symmetrical waveforms with the reference point shifted by 0-a.

Here, if the same calculation as described above is performed, it can be seen that the same effect can be obtained in any of S = 30 +, θ = 9Ο +, and θ = 1550 + α.

However, the change in magnetic energy when the rising portion 5-2 of the magnetic pole passes through the front edge portion 411 is caused by the magnetic energy when the falling portion 5-1 of the magnetic pole passes through the front edge portion 4-1. In general, the cogging torque does not become extremely small when the change is smaller than 0. In order to obtain a larger effect, 0 = 90 0-α, 0 = 150-0; It is desirable to set it to 0—one.

In the above-described embodiment, the configuration in which a magnet having a width smaller than the magnetic pole pitch is fixed to the inner peripheral portion of the annular back yoke has been described, but as shown in FIG. 6, the magnet is magnetized in the radial direction and the circumferential direction. The same effect is obtained in the case of a so-called Halpa-eight array magnet configuration in which magnets are alternately bonded, or in the case of using an integral cylindrical magnet (not shown) or a configuration in which an unmagnetized portion is provided between magnetic poles.

In the above, the configuration of the mouth-to-mouth type is shown, but as shown in Fig. 7, it is needless to say that the mouth-to-night type configuration in which the mouth is the inner circumference and the core is the outer circumference is also possible. Absent.

Note that Fig. 7 shows an embedded magnet configuration in which two flat permanent magnets are inserted in the back yoke for each magnetic pole.In this case, a plurality of permanent magnets are used for each magnetic pole. The same effect can be obtained even in the case of a magnet-embedded configuration.

(Second embodiment)

In the first embodiment, the number of magnetic poles is 8, and the number of salient poles is 6 (in other words, the number of magnetic poles: The case where the number of salient poles is 4: 3) is shown, but it can be applied to the case where the ratio of the number of magnetic poles to the number of salient poles is different from the above.

Fig. 8 is an explanatory diagram showing a brushless motor (^ magnetic circuit configuration) in the second embodiment. In Fig. 8, the number of magnetic poles per mouth is 14 and the number of core salient poles is 12. In the case of brushless mode, the basic cogging tracing waveform is a repetitive waveform of 84 times per mode rotation (repetitive waveform with an electrical angle of 30 °).

This is because, in the torque waveform generated by one salient pole shown in (Equation 4) above, the trilec whose order is lower than the sixth-order component (sin (1 2 x) component) is due to the torque generated by the other salient poles. This indicates that the motor does not appear as cogging torque as a whole because it is canceled. (Equation 4) is shown below again. a X (sin (2) + sm (2x-2 (θ + a)) + bx (sin (4x) + sin (4x-4 (θ + α))

+ cx (sin (6x) + sin (6z-6 (θ + a)) + dx (sin (8x) + sin (8x-8 (θ + a))

+ ex (sin (10x) + sin (10x-1Ό (Θ + a) 12) + f x (sin (12) 4-sin (12x -12 (θ + α))

(Equation 4) Here, in the first embodiment, the value of 0 is adjusted to remove the third-order component (sin (6 x) component) of the torque generated by one salient pole. In the case of the second embodiment, if the value of 0 is adjusted and the sixth-order component (sin (1 2 x) component) of torque generated by one salient pole is removed, the fundamental component of the cogging torque can be obtained. It can be seen that is eliminated and the absolute value can be reduced.

Specifically, by setting 0 = 165-0: or 0 = 195-α, ^: 0 = 225-0; or 0 = 255-α, the cogging torque can be minimized. It can be J ヽ. Here, considering the case where the cogging torque goes to some extent from 0 = 195-c¾, where the cogging torque becomes the minimum, if 0 = 190-α or 0 = 200-ο; The 6th-order component of the cogging torque generated at the pole is removed by 50%, and when the opening angle of the salient pole is set to 19.2. The 6th-order component of luk is removed by 74%, and in order to obtain practical performance, the 6th-order component of the cogging torque generated by salient poles is reduced to about 1/4 or less. — By setting α to 197.5—Q !, the fundamental period component of the cogging torque is greatly reduced, and the cogging torque can be kept small.

When the salient pole tip is made non-concentric as shown in Fig.5A, Fig.5B and Fig.5C, or when the effect of magnetic saturation of the core is considered, the salient pole is When the opening angle of the salient pole is slightly larger (around 5 degrees in electrical angle), the cogging torque may be minimized. Therefore, in general, the cogging torque can be suppressed to a small value by setting the salient pole opening angle 0 to 202.5-α from 192.5-α.

The same idea can be considered for other magnetic pole numbers: slot numbers. Table 1 shows the relationship between the number of magnetic poles: the number of slots and the salient pole opening angle that minimizes cogging torque. By setting the salient pole opening angle 0 to the angle range shown in Table 1, the cogging torque can be reduced.

【table 1】

Number of magnetic poles: Number of prongs Protrusion that minimizes cogging torque: ^

85— α <θ <1 ΟΟ—

4: 3 1 45—ff <0 <1 60--Of others

205— α <θ <220--or

1 28. 33— or <0 <1 36. 66— a

1 8.33—α <θ <1 56.66

8: 9 1 68. 33— Qf <0 <1 7 β. 67—— Ot and others

1 88. 33— α <θ <1 96. 67— or

2 Ο 8.33— (Χ <θ <Ζ 1 6.67― a

228. 33— α <θ <236. 67— or

1 48. 33— α <θ <1 56. 67—

1 68. 33— α <θ <1 76. 67— or

1 O: 9 1 88.33—α <0 <1 Θ 6.67—oc

2 Ο 8.33—α <θ <21 6.67

228. 33— α <θ <236. 67— a

248. 33— α <θ <256. 67

1 Ο 2.5—α <θ <1 12.5—cr

1 32 .5— ΟΓ <0 <12.5—

1 o: Λ 2 162.5-α <θ <172.5-or other

1 92. 5— α <0 <2 Ο 2. S— cx

222. 5— 0Γ <θ <232. 5— Of

1 32, 5— ατ <θ <1 2.5-or

1 62. 5— α <0 <1 72.5 — or

1: 1 2 1 92.5—α <0 <202.5—of other

222. 5— α <θ <232. 5— Of

252. 5— ΟΤ <0 <262. 5— Of

Table 1 is specifically described. A mouth with a magnet body with 2 m of magnetic poles alternately magnetized with N and S poles in the rotation direction, and a salient pole 3 n with a coil wound radially opposite to this magnet body And a core provided with salient poles. In the magnet body, the difference between the magnetic flux generating portion of each pole and the magnetic pole pitch is reduced to an electrical angle, that is, the magnet body surface is configured to generate magnetic flux in a range substantially smaller than the magnetic pole pitch by an electrical angle α. Ma If the opening angle of the salient poles is an electrical angle Θ, a structure β5 that satisfies the relationship of (Equation 1) is obtained. Where h in (Equation 1) is the least common multiple of 2 m and 3 η, and k is a natural number. , _.λ (Equation 1)

As a result, a motor with reduced cogging torque can be provided.

In the above description, the magnet body surface is configured to generate magnetic flux in a range substantially smaller than the magnetic pole pitch by an electrical angle. However, when the magnetic poles are provided without gaps, it is assumed that α = By setting the value to 0 so as to satisfy the relationship of (Equation 5), it is possible to provide a motor in which the cogging torque is similarly reduced.

(Equation 5)

(Third embodiment)

FIG. 9 is an explanatory diagram illustrating a configuration of a magnetic nr path in the brushless motor according to the third embodiment.

As shown in Fig. 9, the opening angle of the salient pole 4 tip of the core 3 is 170 °, and the pitch of the salient pole tip alternates between 225 ° and 255 ° in electrical angle. It is a feature point.

The difference from the conventional technology is that the permanent magnets of the magnetic poles are fixed with a gap of 40 electrical degrees between them, and the magnetic field is partially generated within the electrical angle of 140 degrees. And the salient pole opening angle of the core of the basic shape is 170 ° in electrical angle.

Specifically, as shown in Fig. 108 and Fig. 10B, the two cores 3-1 and 3-2 with the same shape and angular force S shifted by 15 ° in electrical angle should be combined with the shaded portions. It is composed of

As described above, in the present embodiment, in the configuration of the first embodiment, the opening angle of the salient pole is An electric angle of 170 ° is assumed, and a shape that generates a cogging torque having a period of 2/01 of the basic period of the cogging torque is used as a base, and an electric angle of 1/4 of the basic period of the cogging torque is 15 ° Combines two core shapes shifted by minutes. With this configuration, it is possible to provide a motor with extremely small absolute linearity and high rotational accuracy in a cycle that is one-fourth of the basic cogging torque cycle.

In addition, as shown in Fig. 12A and Fig. 12B, when the two cores are configured by combining the shaded portions of 形 ^, the shape in which the opening angle of the salient poles differs on the left and right as shown in Fig. 11 can be obtained. Can be configured.

Further, FIGS. 9 and 11 show the case where the number of magnetic poles is 8 and the number of salient poles is 6 C. However, it is needless to say that the same configuration can be applied to other magnetic poles and salient poles. There is no. Fig. 13 shows an example when the number of magnetic poles is 14 and the number of salient poles is 12. The core shape shown in FIG. 13 is configured by combining the shaded portions of the two core shapes ^^ shown in FIGS. 14A and 14B.

Here, the cores shown in FIGS. 14A and 14B are configured so as to adjust the angle of struggle 0 at the tip of the salient pole and generate a cogging torque having a half cycle of the basic cycle of the cogging torque. Furthermore, by combining the shapes shifted by an electrical angle of 7.5 °, which is a quarter of the basic cycle of the cogging torque, the cogging torque base; ^: A quarter of the cycle (3 3 6 times per rotation) And the absolute value of the cogging torque becomes extremely small.

Similarly, in general, a rotor having a magnet body with 2 m of magnetic poles, alternately magnetized with N and S poles in the rotation direction, and a coil wound around this magnet body in the radial direction The gnet body has a core provided with salient poles having 3 n salient poles, and the difference between the magnetic flux generating portion of each pole and the magnetic pole pitch is defined as an electrical angle α. The magnetic flux is generated in a narrow range of the real electrical angle α. Assuming that the opening angle of the salient pole is 0 electrical angle, the configuration satisfies the relationship of (Equation 1). This (expression Based on the basic shape that satisfies the relationship of (1), it is generated by composing a timely combination of j core basic shapes shifted by an angle of 1/2 j of the basic cogging cycle in the rotation direction. The cogging torque is less than one-fourth of the basic cogging torque cycle, the absolute value can be extremely small, and a motor with high rotation accuracy can be provided. In Equation 1, h is the least common multiple of 2m and 3n, and k is a natural number. -a (Equation 1)

In the above description, the magnetic body surface is configured to generate magnetic flux in a range substantially smaller than the magnetic pole pitch by an electrical angle α. However, if the magnetic poles are provided without gaps, the expression

= 0,

360m, 1 1 \ _n 360m /. 1 1 \ _c

-\ k \ <θ <-\ k—— + —— +5 (Equation 5) h \ 2 12) h \ 2 12)

The basic shape that satisfies the relationship is used as a base, and it is generated by appropriately combining j core basic shapes that are shifted by an angle of 1/2 j of the basic cogging cycle in the rotation direction. The cogging torque is less than one-fourth of the basic cogging torque period, the absolute value can be extremely small, and a motor with high rotation accuracy can be provided. Industrial applicability

ADVANTAGE OF THE INVENTION The brushless motor of this invention has the advantageous effect that the cogging torque of a motor can be reduced and the rotational accuracy of a motor can be improved. For example, it is useful for mobile devices as a drive source for various devices such as video / audio devices and 0 A devices.

Claims

The scope of the claims

1. A rotor having a magnet body of 2 m in number of magnetic poles alternately magnetized with N and S poles in the rotation direction, and a salient pole of 3 n with a coil wound radially opposite to the magnet body and wound with a coil Wherein the magnet body has a difference between a magnetic flux generating portion of each pole and a magnetic pole pitch as an electrical angle, an opening angle of the salient pole as an electrical angle 0, and h as 2 m and 3 n. A brushless motor characterized by satisfying the relationship of (Equation 1), where k is a natural number. + 5 (Equation 1)

2. The ratio according to claim 1, wherein the ratio between the number of magnetic poles and the number of salient poles has a ratio of 4: 3, and satisfies one of the following three conditions. Bra Silesmo evening.

8 5-<θ <1 0 0-α

145-α <θ <1 6 0— α

20 5-α; <θ <2 2 0-θ!

3. The ratio according to claim 1, wherein the ratio between the number of magnetic poles and the number of salient poles is 8: 9, and satisfies one of the following four conditions. Bra Silesmo evening.

1 68. 3 3-α <θ <1 7 6.6 7-1 88.33-<θ <1 9 6.6 7-

20 8.33-<θ <2 1 6.6 7-a 22 8.33-<θ <2 3 6.6 7-

4. The ratio according to claim 1, wherein the ratio between the number of magnetic poles and the number of salient poles is 10 to 9, and satisfies one of the following five conditions. Brasilesmo evening.

1 68. 3 3-<θ <1 76. 6 7-a

1 88. 33- <θ <1 96. 6 7-a

2 0 8.33-<θ <2 1 6.67 -a

2 2 8. 3 3-<θ <236.67-248.33

5. The ratio between the number of magnetic poles and the number of salient poles has a configuration of 10 to 12, and satisfies one of the following three conditions. Brushless motor.

1 62. 5- <θ <1 72.5

1 92. 5 _ く Θ Θ Θ 2 02. 5-2 2 2.5 1 <θ <2 32. 5— α

6. The ratio of the number of magnetic poles to the number of salient poles is configured to be 14 to 12, and satisfies one of the following four conditions. A brushlessmo overnight.

1 62.5-α <θ <1 72.5-α

1 92.5 — <θ <2 02.5-222.5-<θ <2 32.5 — α

2 52.5-1- <θ <2 62.5—α

7. The brushless motor according to claim 1, wherein a difference between a magnetic flux generating portion of each pole and a magnetic pole pitch of the magnet body is substantially zero.

8. The brushless brush according to claim 7, wherein the ratio between the number of magnetic poles and the number of salient poles is 8: 9, and satisfies one of the following two conditions. Sumota.

1 28.3 3 <0 <1 36.6 7

148.3 3 <θ <1 5 6.67

9. The ratio according to claim 7, wherein the ratio between the number of magnetic poles and the number of salient poles has a configuration of 10 to 9, and satisfies one of the following three conditions. Plush motor.

148.3 3 <θ <1 5 6.67

1 6 8.3 3 <θ <1 7 6.6.7

1 8 8. 3 3 <θ <1 96.67

10. The ratio between the number of magnetic poles and the number of salient poles has a configuration of 10 to 12, and satisfies one of the following two conditions. Bute Silesmo overnight.

1 0 2.5 <0 <1 1 2.5

1 32.5 <0 <1 2.5

11. The ratio between the number of magnetic poles and the number of salient poles is configured to be 14 to 12, and the condition of any one of the following three formulas is satisfied. Brushlessmo overnight.

1 32.5 <θ <1 42.5

1 62.5 <θ <1 72.5

1 9 2.5 <0 <20 2.5

12. The brushless motor according to claim 1, wherein the core has a configuration in which salient poles are shifted by a predetermined angle in a rotation direction.