JP2022139210A - Brushless motor and motor device - Google Patents

Abstract

To provide a brushless motor capable of obtaining saliency without increasing manufacturing cost.SOLUTION: A brushless motor comprises: a shaft 10; a rotor core 20 having a first outer circumferential surface 20b, and having a first inner circumferential surface 20a integrated with the shaft or facing the shaft; and at least one ring-type magnet having a second outer circumferential surface 30b and a second inner circumferential surface 30a. The shaft is rotatably supported around a rotation axis parallel to an axial direction being an extension direction of the shaft. The second inner circumferential surface faces the first outer circumferential surface. In the second outer circumferential surface, an N pole and an S pole are alternately magnetized in a first cycle in a circumferential direction being a direction along a circumference around an axis of rotation. The rotor core has an outer circumferential part on a first outer circumferential surface side. Magnetic reluctance of the rotor core in the outer circumferential part varies in a first cycle in the circumferential direction.SELECTED DRAWING: Figure 2

Description

The present invention relates to brushless motors and motor devices.

Brushless motors include brushless motors using embedded magnet rotors and brushless motors using surface magnet rotors. In a brushless motor using an embedded magnet type rotor, field weakening control, detection of the rotor position at the time of starting, etc. are performed by utilizing a change in inductance (saliency) between the rotor and the magnetic poles of the stator.

A brushless motor using a surface magnet type rotor is more likely to obtain high torque than a brushless motor using an embedded magnet type rotor. However, it is difficult to obtain saliency in the surface magnet type rotor. In particular, brushless motors using ring-shaped magnets could hardly obtain saliency. Therefore, in a brushless motor using a surface magnet type rotor, the above control or detection is difficult.

In the brushless motor described in Patent Document 1 (Japanese Patent Application Laid-Open No. 2009-131070), protrusions are formed on the outer peripheral surface of the rotor core, and recesses to be fitted to the protrusions are formed on the inner peripheral surface of the ring-shaped magnet. Thus, saliency is obtained. In the brushless motor described in Patent Document 2 (Japanese Patent Application Laid-Open No. 2016-049010), saliency is obtained by attaching a magnetic metal to the outer peripheral surface of the ring-shaped magnet.

Japanese Patent Application Laid-Open No. 2009-131070 JP 2016-049010 A

In the brushless motor disclosed in Patent Document 1, it is necessary to fit the protrusions of the rotor core and the recesses of the ring-shaped magnet, which increases the manufacturing cost due to the improvement of assembly accuracy and the occurrence of additional man-hours. do. Further, in the brushless motor disclosed in Patent Document 1, since it is necessary to attach the magnetic metal to the ring-shaped magnet, the manufacturing cost increases due to an increase in the number of parts, an increase in the number of assembly steps, and the like.

The present invention has been made in view of the problems of the prior art as described above. More specifically, the present invention provides a brushless motor capable of obtaining saliency without increasing manufacturing costs and a motor device having the same.

A brushless motor according to an aspect of the present invention includes a rotor having a shaft, a first outer peripheral surface, and a first inner peripheral surface integrated with the shaft or facing the shaft, and a second outer peripheral surface. at least one ring-shaped magnet having a surface and a second inner peripheral surface. The shaft is rotatably supported around a rotation axis parallel to the axial direction in which the shaft extends. The second inner peripheral surface faces the first outer peripheral surface. The second outer peripheral surface is magnetized with N poles and S poles alternately with a first cycle in the circumferential direction, which is a direction along the circumference centered on the rotation axis. The rotor core has an outer peripheral portion on the first outer peripheral surface side. The magnetic reluctance of the rotor core in the outer peripheral portion changes in the circumferential direction at the first period.

In the brushless motor described above, a gap may be formed in the outer peripheral portion. The rotor core may be made of a magnetic material. In the above brushless motor, the gap may be filled with a non-magnetic material.

In the brushless motor described above, a gap may be formed in the outer peripheral portion, and the gap may be filled with a magnetic material. The rotor core may be made of a non-magnetic material.

In the above brushless motor, the circumferential positions of the portion magnetized to the N pole and the portion magnetized to the S pole on the second outer peripheral surface may vary along the axial direction.

In the brushless motor described above, the at least one ring-shaped magnet may be a plurality of ring-shaped magnets stacked in the axial direction. In two of the plurality of ring-shaped magnets adjacent in the axial direction, the positions in the circumferential direction of the portion magnetized to the north pole and the portion magnetized to the south pole on the second outer peripheral surface are shifted from each other. may

The above brushless motor may further include a stator having a plurality of magnetic poles arranged in a second cycle in the circumferential direction and facing the second outer peripheral surface.

A motor device according to an aspect of the present invention includes the brushless motor described above and a controller. The controller is configured to control the brushless motor based on a change in mutual inductance between two of the plurality of circumferentially adjacent magnetic poles.

In the above motor device, the controller may be configured to perform field weakening control for the brushless motor based on a change in mutual inductance between two of the plurality of magnetic poles adjacent in the circumferential direction.

In the above motor device, the controller may be configured to perform advance angle control for the brushless motor based on a change in mutual inductance between two of the plurality of magnetic poles adjacent in the circumferential direction.

In the above motor device, the controller detects the position of the rotor core based on a change in mutual inductance between two of the plurality of magnetic poles adjacent in the circumferential direction, and starts the brushless motor based on the detected position of the rotor core. It may be configured to control.

The above motor device may further include a case housing the brushless motor. The controller may be built into the case or integrally coupled to the case.

According to the brushless motor and motor device according to one aspect of the present invention, it is possible to obtain saliency without increasing manufacturing costs.

2 is a cross-sectional view of brushless motor 100. FIG. FIG. 2 is a cross-sectional view along II-II in FIG. 1; FIG. 4 is a first explanatory diagram for explaining the effects of the brushless motor 100; FIG. 8 is a second explanatory diagram for explaining the effect of the brushless motor 100; FIG. 5 is a cross-sectional view of a brushless motor 100 according to Modification 1; FIG. 11 is a cross-sectional view of a brushless motor 100 according to Modification 2; FIG. 11 is a cross-sectional view of a brushless motor 100 according to Modification 3; FIG. 11 is a perspective view of a ring-shaped magnet 30 included in a brushless motor 100 according to Modification 4; FIG. 11 is a perspective view of a plurality of ring-shaped magnets 30 included in brushless motor 100 according to modification 5; 2 is a block diagram of a motor device 200; FIG.

Details of embodiments of the present invention will be described with reference to the drawings. In the drawings below, the same or corresponding parts are denoted by the same reference numerals, and redundant description will not be repeated.

(Brushless motor according to the embodiment)
A brushless motor (hereinafter referred to as “brushless motor 100”) according to an embodiment will be described.

Hereinafter, the direction along the central axis A of the shaft 10 in the extending direction of the shaft 10 is defined as the axial direction, the direction along the circumference centered on the central axis A is defined as the circumferential direction, and the direction orthogonal to the axial direction is defined as the radial direction. direction.

<Configuration of Brushless Motor 100>
FIG. 1 is a cross-sectional view of a brushless motor 100. FIG. FIG. 1 shows a cross section of brushless motor 100 parallel to and passing through central axis A. As shown in FIG. FIG. 2 is a cross-sectional view along II-II in FIG. As shown in FIGS. 1 and 2, the brushless motor 100 has a shaft 10, a rotor core 20, a ring-shaped magnet 30, and a stator 40. As shown in FIG.

The shaft 10 extends axially. As described above, the central axis A of shaft 10 is parallel to the axial direction. A shaft 10 is rotatably supported around a central axis A by bearings 11 and 12 . The bearings 11 and 12 are rolling bearings, for example.

A rotor core 20 is attached to the shaft 10 . The rotor core 20 is attached concentrically to the shaft 10 . The rotor core 20 is made of a magnetic material. In order to reduce iron loss due to eddy currents, the rotor core 20 is preferably formed by laminating magnetic steel sheets, for example. The rotor core 20 has an inner peripheral surface 20a and an outer peripheral surface 20b. The rotor core 20 may be integrated with the shaft 10 . In this case, rotor core 20 does not have inner peripheral surface 20a.

The inner peripheral surface 20a extends in the circumferential direction. The inner peripheral surface 20a faces the central axis A side. The inner peripheral surface 20 a faces the shaft 10 . The rotor core 20 is attached to the shaft 10 at the inner peripheral surface 20a. The outer peripheral surface 20b extends in the circumferential direction. The outer peripheral surface 20b faces the side opposite to the central axis A. As shown in FIG. That is, the outer peripheral surface 20b is the opposite surface of the inner peripheral surface 20a in the radial direction.

The rotor core 20 has an outer peripheral portion 21 . The outer peripheral portion 21 is a portion on the outer peripheral surface 20 b side of the rotor core 20 . A gap 22 is formed in the outer peripheral portion 21 . The details of the gap 22 will be described later.

The ring-shaped magnet 30 has a ring-shaped shape. A ring-shaped magnet 30 is attached to the rotor core 20 . The ring-shaped magnet 30 is attached concentrically to the rotor core 20 . The ring-shaped magnet 30 has an inner peripheral surface 30a and an outer peripheral surface 30b.

The inner peripheral surface 30a extends in the circumferential direction. The inner peripheral surface 30a faces the central axis A side. The inner peripheral surface 30a faces the outer peripheral surface 20b. The ring-shaped magnet 30 is attached to the rotor core 20 on the inner peripheral surface 30a. The outer peripheral surface 30b extends in the circumferential direction. The outer peripheral surface 30b faces the side opposite to the central axis A. As shown in FIG. That is, the outer peripheral surface 30b is the opposite surface of the inner peripheral surface 30a in the radial direction.

The ring-shaped magnet 30 has an inner peripheral portion 31 and an outer peripheral portion 32 . The inner peripheral portion 31 is the portion on the inner peripheral surface 30 a side of the ring-shaped magnet 30 , and the outer peripheral portion 32 is the portion on the outer peripheral surface 30 b side of the ring-shaped magnet 30 . The inner peripheral portion 31 is divided into a plurality of regions 31a and 31b in the circumferential direction. The regions 31a and 31b are alternately arranged in the first period in the circumferential direction. The outer peripheral portion 32 is divided into a plurality of regions 32a and 32b in the circumferential direction. The regions 32a and 32b are alternately arranged in the first period in the circumferential direction. The first period is defined by a virtual straight line connecting the center of one region 31a (region 32a) and the central axis A, and the center and the central axis A of a region 31b (region 32b) adjacent to the one region 31a (region 32a). It is the angle formed by the connected virtual straight line.

The regions 31a and 31b are the north and south poles of the ring magnet 30, respectively. Regions 32a and 32b are the south and north poles of ring magnet 30, respectively. The regions 31a and 32a are radially adjacent to each other, and the regions 31b and 32b are radially adjacent to each other. That is, the outer peripheral surface 30b is magnetized alternately with N poles and S poles in the first period in the circumferential direction.

In brushless motor 100 , gaps 22 are grooves 23 . The groove 23 is formed in the outer peripheral surface 20b. The groove 23 extends radially toward the inner peripheral surface 20a. The groove 23 axially penetrates the rotor core 20 . The number of grooves 23 is plural. The grooves 23 are arranged with a first period in the circumferential direction. At the position where the groove 23 is formed, since there is no member forming the rotor core 20, the magnetic resistance is higher than at the position where the groove 23 is not formed. That is, the magnetic resistance of the rotor core 20 in the outer peripheral portion 21 changes in the first period. Although not shown, the gap 22 (groove 23) may be filled with a non-magnetic material (eg, non-magnetic metal material or resin material).

From another point of view, an imaginary straight line connecting the center of one groove 23 and the central axis A and an imaginary straight line connecting the center of another groove 23 adjacent to the one groove 23 and the central axis A The angle formed by the virtual straight line connecting the center of one region 31a (region 32a) and the central axis A and the center of the region 31b (region 32b) adjacent to the one region 31a (region 32a) and the central axis A It is equal to the angle formed by the connected imaginary straight line.

Stator 40 is arranged concentrically with shaft 10 and rotor core 20 . The stator 40 is formed, for example, by laminating electromagnetic steel sheets in order to reduce iron loss due to eddy currents. The stator 40 has an inner peripheral surface 40a and an outer peripheral surface 40b.

The inner peripheral surface 40a extends in the circumferential direction. The inner peripheral surface 40a faces the central axis A side. The inner peripheral surface 40a faces the outer peripheral surface 30b with a gap therebetween in the radial direction. The outer peripheral surface 40b extends in the circumferential direction. The outer peripheral surface 40b faces the side opposite to the central axis A. As shown in FIG. That is, the outer peripheral surface 40b is the opposite surface of the inner peripheral surface 40a in the radial direction. The stator 40 is attached to the case 60 at the outer peripheral surface 40b. Thereby, the brushless motor 100 is arranged inside the case 60 .

The stator 40 has an outer peripheral portion 41 and magnetic poles 42 . The outer peripheral portion 41 is a portion on the outer peripheral surface 40b side of the stator 40 . The number of magnetic poles 42 is plural. The magnetic poles 42 have a set of U poles 42a, V poles 42b and W poles 42c. The number of sets is, for example, plural. The magnetic pole 42 extends radially inward from the outer peripheral portion 41 .

The magnetic poles 42 are arranged with a second period in the circumferential direction. The second period is the angle between a virtual straight line connecting the center of one magnetic pole 42 and the central axis A and a virtual straight line connecting the center of another magnetic pole 42 adjacent to the magnetic pole 42 and the central axis A. . The second period is typically different from the first period, but may be the same as the first period. In the examples shown in FIGS. 1 and 2, the second period is different from the first period.

A slot 43 is provided between two magnetic poles 42 adjacent in the circumferential direction. The slots 43 pass through the stator 40 along the axial direction. A coil 50 is passed through the slot 43 and wound around the magnetic pole 42 . When the coil 50 is energized, the magnetic poles 42 are sequentially excited, and a rotational force acts on the ring magnet 30 . This rotational force causes the shaft 10 to rotate.

<Effect of brushless motor 100>
FIG. 3 is a first explanatory diagram for explaining the effect of the brushless motor 100. FIG. FIG. 4 is a second explanatory diagram for explaining the effect of the brushless motor 100. FIG. As shown in FIGS. 3 and 4, two adjacent magnetic poles 42 (eg, U pole 42a and V pole 42b) are coupled through magnetic flux F with mutual inductance. This mutual inductance increases as the magnetic resistance in the path along which the magnetic flux F passes decreases. In the state of FIG. 3, since there is no air gap 22 (groove 23) on the path of the magnetic flux F, mutual inductance is increased. On the other hand, in the state of FIG. 4, since there is an air gap 22 (groove 23) on the path of the magnetic flux F, the mutual inductance is small. This change in mutual inductance provides saliency.

The rotor core 20 is formed, for example, by press working using laminated electromagnetic steel sheets. Therefore, in order to form the voids 22 (grooves 23), it is sufficient to change the shape of the mold when performing this press working. Therefore, according to the brushless motor 100, saliency can be obtained without increasing the manufacturing cost.

<Brushless motor 100 according to Modification 1>
A brushless motor 100 according to Modification 1 will be described. Here, differences from brushless motor 100 will be mainly described, and redundant description will not be repeated.

FIG. 5 is a cross-sectional view of brushless motor 100 according to Modification 1. As shown in FIG. FIG. 5 shows a cross section of brushless motor 100 according to Modification 1 at a position corresponding to FIG. As shown in FIG. 5, void 22 includes square hole 24 in addition to groove 23 .

The number of square holes 24 is plural. The square hole 24 axially penetrates the rotor core 20 . Both ends of the square hole 24 in the longitudinal direction are positioned to face the bottom of one groove 23 and the bottom of another groove 23 adjacent to the one groove 23 . Also in this case, since the magnetic resistance of the rotor core 20 on the path of the magnetic flux F changes in the first period, saliency can be obtained as in the case of the brushless motor 100 .

<Brushless motor 100 according to modification 2>
A brushless motor 100 according to Modification 2 will be described. Here, differences from brushless motor 100 will be mainly described, and redundant description will not be repeated.

FIG. 6 is a cross-sectional view of brushless motor 100 according to Modification 2. As shown in FIG. FIG. 6 shows a cross section of brushless motor 100 according to modification 2 at a position corresponding to FIG. As shown in FIG. 6, the gap 22 includes a first circular hole 25 and a second circular hole 26 instead of the groove 23. As shown in FIG.

The number of first circular holes 25 is plural. The first circular holes 25 are arranged at a first period in the circumferential direction. The number of second circular holes 26 is plural. The inner diameter of the second circular hole 26 is larger than the inner diameter of the first circular hole 25 . The second circular holes 26 are arranged at a first period in the circumferential direction. The second circular hole 26 is located at an intermediate position between two adjacent first circular holes 25 in the circumferential direction. The second circular hole 26 is positioned further away from the outer peripheral surface 20b than the first circular hole 25 in the radial direction. Thus, the gap 22 does not have to be in contact with the outer peripheral surface 20b. Also in this case, since the magnetic resistance of the rotor core 20 on the path of the magnetic flux F changes in the first period, saliency can be obtained as in the case of the brushless motor 100 .

<Brushless motor 100 according to Modification 3>
A brushless motor 100 according to Modification 3 will be described. Here, differences from brushless motor 100 will be mainly described, and redundant description will not be repeated.

FIG. 7 is a cross-sectional view of brushless motor 100 according to Modification 3. As shown in FIG. FIG. 7 shows a cross section of brushless motor 100 according to Modification 3 at a position corresponding to FIG. As shown in FIG. 7, in brushless motor 100 according to Modification 3, gap 22 (groove 23) is filled with a magnetic material. Also, in the brushless motor 100 according to Modification 3, the rotor core 20 is made of a non-magnetic material (for example, a non-magnetic metal material or a resin material). Also in this case, since the magnetic resistance of the rotor core 20 on the path of the magnetic flux F changes in the first period, saliency can be obtained as in the case of the brushless motor 100 .

<Modification 4>
A brushless motor 100 according to Modification 4 will be described. Here, differences from brushless motor 100 will be mainly described, and redundant description will not be repeated.

FIG. 8 is a perspective view of a ring-shaped magnet 30 included in brushless motor 100 according to Modification 4. As shown in FIG. As shown in FIG. 8, in the brushless motor 100 according to Modification 4, the positions in the circumferential direction of the portion magnetized to the N pole and the portion magnetized to the S pole on the outer peripheral surface 30b are in the axial direction. is changing along That is, in the brushless motor 100 according to Modification 4, the outer peripheral surface 30b is skew-magnetized.

<Modification 5>
A brushless motor 100 according to Modification 5 will be described. Here, differences from brushless motor 100 will be mainly described, and redundant description will not be repeated.

FIG. 9 is a perspective view of a plurality of ring-shaped magnets 30 included in brushless motor 100 according to Modification 5. As shown in FIG. As shown in FIG. 9, a brushless motor 100 according to Modification 5 has a plurality of ring-shaped magnets 30 that are stacked in the axial direction. In the ring-shaped magnets 30 adjacent in the axial direction, the positions of the portions magnetized to the N pole and the portions magnetized to the S pole on the outer peripheral surface 30b are shifted from each other in the circumferential direction. The direction of this deviation is the same from the ring-shaped magnet 30 at one end in the axial direction to the ring-shaped magnet 30 at the other end in the axial direction. That is, the plurality of ring-shaped magnets 30 constitute a stepped skew magnetic pole.

(Motor device according to the embodiment)
A motor device (hereinafter referred to as "motor device 200") according to the embodiment will be described.

FIG. 10 is a block diagram of the motor device 200. As shown in FIG. As shown in FIG. 10, the motor device 200 has a brushless motor 100, an inverter circuit 110, a PWM pulse generation circuit 120, and a controller . Preferably, inverter circuit 110 , PWM pulse generator circuit 120 and controller 130 are built in or integrated in case 60 .

The inverter circuit 110 is connected to the brushless motor 100 . The output current from inverter circuit 110 flows through coil 50 wound around magnetic pole 42 . As a result, the magnetic poles 42 are sequentially excited. PWM pulse generation circuit 120 is connected to inverter circuit 110 . More specifically, a PWM (Pulse Width Modulation) pulse from PWM pulse generating circuit 120 is supplied to the gate of each switching element (transistor) forming inverter circuit 110 . Based on this, the inverter circuit 110 supplies the above output current to the coil 50 wound around the magnetic pole 42 . The PWM pulse generation circuit 120 changes the PWM pulse based on the control signal from the controller 130 .

The controller 130 is composed of, for example, a DSP (Digital Signal Processor) or a microcontroller. The controller 130 is connected to the signal line connecting the brushless motor 100 and the inverter circuit 110 and to the PWM pulse generation circuit 120 . As the rotor core 20 rotates, the mutual inductance between the two adjacent magnetic poles 42 fluctuates, causing the current flowing through the signal line connecting the inverter circuit 110 to fluctuate. The controller 130 performs various controls on the brushless motor 100 by changing the above-described control signal based on the fluctuation of this current, that is, the fluctuation of the mutual inductance between the two adjacent magnetic poles 42 .

More specifically, the controller 130 may perform field weakening control based on variations in mutual inductance between two adjacent magnetic poles 42 . Field-weakening control is a control that obtains effects such as an increase in rotational speed by weakening a magnetic field with a d-axis current using vector control. The controller 130 may also perform advance angle control based on variations in mutual inductance between two adjacent magnetic poles 42 . Advance angle control refers to control that obtains effects such as an increase in rotation speed by advancing the phase of the excitation voltage of the stator relative to the rotational phase of the magnetic poles due to the rotation of the rotor.

Further, the controller 130 detects the position of the rotor core 20 based on the variation in mutual inductance between the two adjacent magnetic poles 42, and controls the starting of the brushless motor 100 based on the detected position of the rotor core 20. good too.

Although the embodiment of the present invention has been described as above, it is also possible to modify the above embodiment in various ways. Moreover, the scope of the present invention is not limited to the above embodiments. The scope of the present invention is indicated by the scope of claims, and is intended to include all changes within the meaning and scope of equivalence to the scope of claims.

The above embodiments are particularly advantageously applied to brushless motors and motor devices with brushless motors.

10 shaft, 11 bearing, 12 bearing, 20 rotor core, 20a inner peripheral surface, 20b outer peripheral surface, 21 outer peripheral portion, 22 gap, 23 groove, 24 square hole, 25 first circular hole, 26 second circular hole, 30 ring type Magnet 30a inner peripheral surface 30b outer peripheral surface 31 inner peripheral portion 31a region 31b region 32 outer peripheral portion 32a region 32b region 40 stator 40a inner peripheral surface 40b outer peripheral surface 41 outer peripheral portion 42 magnetic pole , 43 slot, 50 coil, 60 case, 100 brushless motor, 110 inverter circuit, 120 pulse generation circuit, 130 controller, 200 motor device, A central shaft, F magnetic flux.

Claims (12)

an axis;
a rotor core having a first outer peripheral surface and having a first inner peripheral surface integral with or facing the shaft;
at least one ring-shaped magnet having a second outer peripheral surface and a second inner peripheral surface;
The shaft is rotatably supported around a rotation axis parallel to the axial direction that is the extending direction of the shaft,
The second inner peripheral surface faces the first outer peripheral surface,
The second outer peripheral surface is magnetized with N poles and S poles alternately in a first cycle in the circumferential direction, which is a direction along the circumference centered on the rotation axis,
The rotor core has an outer peripheral portion on the first outer peripheral surface side,
The brushless motor, wherein the magnetic resistance of the rotor core in the outer peripheral portion changes in the first period in the circumferential direction. A gap is formed in the outer peripheral portion,
2. The brushless motor according to claim 1, wherein said rotor core is made of a magnetic material. 3. The brushless motor according to claim 2, wherein said air gap is filled with a non-magnetic material. A gap is formed in the outer peripheral portion,
The gap is filled with a magnetic material,
2. The brushless motor according to claim 1, wherein said rotor core is made of a non-magnetic material. 1, wherein positions in the circumferential direction of the portion magnetized to the N pole and the portion magnetized to the S pole on the second outer peripheral surface change along the axial direction. Item 4. The brushless motor according to any one of Item 4. The at least one ring-shaped magnet is a plurality of ring-shaped magnets that are stacked along the axial direction,
In two of the plurality of ring-shaped magnets adjacent in the axial direction, the positions in the circumferential direction of the portion magnetized to the north pole and the portion magnetized to the south pole on the second outer peripheral surface are , are offset from each other. The brushless motor according to any one of claims 1 to 6, further comprising a stator having a plurality of magnetic poles arranged in a second period in the circumferential direction and facing the second outer peripheral surface. motor. The brushless motor according to claim 7;
a controller;
The motor device, wherein the controller is configured to control the brushless motor based on a change in mutual inductance between two of the plurality of magnetic poles adjacent in the circumferential direction. 9. The motor device according to claim 8, wherein said controller is configured to perform field weakening control for said brushless motor based on a change in mutual inductance between two of said plurality of magnetic poles adjacent in said circumferential direction. 9. The motor device according to claim 8, wherein said controller is configured to perform advance angle control for said brushless motor based on a change in mutual inductance between two of said plurality of magnetic poles adjacent in said circumferential direction. . The controller detects the position of the rotor core based on a change in mutual inductance between two of the plurality of magnetic poles adjacent in the circumferential direction, and starts the brushless motor based on the detected position of the rotor core. 9. A motor arrangement according to claim 8, configured to provide control. further comprising a case housing the brushless motor,
12. The motor device according to any one of claims 8 to 11, wherein said controller is built in or integrally coupled with said case.

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