JPH0870562A - Brushless motor - Google Patents

Abstract

PURPOSE: To get high torque by offsetting a part of cogging at non-current application by the magnetomotive force generated by the difference between the magnetizing components and the demagnetizing components of a magnetic flux generated by the current application to each coil of a stator core. CONSTITUTION: Each coil 34 wound on each T (1)-(6) of a stator core forms a network 40, and this network 40 is supplied with a current simultaneously by bidirectional current application by a single-phase power source. At this time, the magnitudes of the magnetizing components and the demagnetizing components of the magnetic flux generated by the current application to each coil 24 different from each other, so a part of the cogging at non-current application can be offset by the magnetomotive force by the difference between these magnetizing components and demagnetizing components. In short, the total of the cogging at non-current application can be offset by the difference between the magnitudes of the magnetizing components and the demagnetizing components of the magnetic flux, consequently smooth torque occurs in a rotor magnet, and the rotor rotates smoothly with low vibration. Hereby, high torque can be obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates generally to small magnet type motors, and more particularly to a brushless motor suitable for spindle motors and various micromotors.

[0002]

2. Description of the Related Art Conventionally, various structures have been adopted for brushless motors such as HDD spindle motors and small magnet type motors, but most of them are
An annular rotor magnet configured by winding a multi-phase coil around each tooth of a stator core having a plurality of slots to form a stator, and facing the stator and alternately arranging different poles in the circumferential direction. Is rotatably provided, and the energization of the multi-phase coil is selectively switched, so that the rotor equipped with the rotor magnet is electromagnetically interacted with the electromagnetic poles on the magnetic pole teeth generated by the coil current and the magnetic poles of the rotor magnet. I am trying to rotate.

In this case, the switching of the energization timing is controlled by detecting the polarity of the rotor magnet and the alternating position of the magnetic flux with a sensor such as a Hall element or the induced voltage of a coil.

By the way, in the brushless motor having such a structure, not only the non-energized goggling is provided between the rotor and the stator, but the starting dead center may be formed depending on the relative position of the two. It has the drawback of increasing the uneven rotation. Therefore, in order to improve the starting reliability of the rotor and suppress the rotation unevenness, a special relationship such as a three-phase drive is given to the number of slots of the stator and the number of magnetic poles of the rotor magnet, or a plurality of sensors are used, or In some cases, a dead center is avoided by providing a starting pole on the stator.

[0005]

However, in the above-mentioned conventional brushless motor, in the structure in which the number of slots of the stator and the number of magnetic poles of the rotor magnet have a special relationship in order to avoid non-energized gogging, Since the combination is limited, there is a problem that there is a region (combination) that is not in practical use due to the non-energized cogging even though the performance such as the rotation torque is high.

Further, in the case of using a plurality of sensors or providing a stator with a compensating pole, the structure becomes complicated due to the necessity of balancing a plurality of elements, and the motor becomes large and expensive. Have

In the prior art, the motor torque fluctuation (dT / dt) is detected and the current change (di) is detected.
There is also a motor that employs a torque unevenness reduction drive control system that is corrected, that is, canceled by / dt), but the circuit means for realizing this is very expensive and is not widely used.

The present invention has been made in view of the above problems of the prior art, and the purpose thereof is to provide high starting reliability without requiring complicated structure. An object of the present invention is to provide a novel brushless motor that can obtain high torque without uneven rotation even when there is non-energized cogging.

[0009]

In order to achieve the above-mentioned object, the present invention is directed to a stator constituted by winding a coil around an arbitrary tooth of a stator core having a plurality of slots, and a stator facing the stator. And a rotor magnet in which different poles are alternately arranged in the circumferential direction, and a sensor for detecting the magnetic flux of the rotor magnet. One coil is wound around each tooth to form one circuit network. The circuit network is configured to be energized at the same time by bidirectional energization with a single-phase power supply, and the sum of the demagnetization component and the increasing component of the magnetic flux generated by energizing each coil is different in magnitude. At least a part of the non-energized cogging is canceled by the magnetomotive force due to the difference in magnitude between the magnetizing component and the demagnetizing component.

In this case, it is easy to implement the polarity of each coil wound around each tooth so that the number of magnetizing and demagnetizing is different. It is also preferable that the number of turns of each coil wound around each tooth be different between the magnetism increase and the magnetism decrease. Further, the coils wound around the teeth may be connected in parallel for increasing magnetism and demagnetizing to make the wire diameter of the winding different.

If the direction of energization of the coil is reversed without including a rest period longer than the magnetic aftereffect time of the stator core, the variation width of the magnetic flux density can be increased. This is preferably done depending on the time, and as a result, high torque can be obtained at the time of starting, locking, and restarting.

[0012]

According to the conventional brushless motor, the coils wound around each tooth of the stator core are selectively excited, and the magnitudes of the magnetic demagnetization component and the magnetic demagnetization component of the magnetic flux generated by the energization of the coils are equal. Therefore, the non-energized cogging will not be canceled by energization.

On the other hand, according to the above-described brushless motor of the present invention, when the coil wound around each tooth of the stator core is excited, at this time, a magnetic flux increasing component generated by energization of each coil is generated. Since the sums of the magnitudes of the demagnetizing component and the demagnetizing component are different, at least a part of the non-energized cogging can be canceled by the magnetomotive force due to the difference in the magnitudes of the magnetizing component and the demagnetizing component. In other words, the total sum of non-energized cogging can be canceled by the magnetomotive force due to the difference in magnitude between the magnetic flux increasing component and the magnetic demagnetizing component. It rotates in the state of.

[0014]

Embodiments of the present invention will be described with reference to the drawings. First, the first embodiment will be described with reference to FIGS. FIG. 2 shows a case where the recording medium such as a CD-ROM is applied to a micromotor for rotationally driving the recording medium. It has been considered that single-phase excitation cannot be used for spindle motors in this field from the viewpoint of tracking and focus errors.

In FIG. 2, a mounting hole 12 is formed in a substrate 10 made of a silicon steel plate or the like fixed to a drive unit, and a cylindrical sleeve 14 is formed in the mounting hole 12 and its axis is orthogonal to the substrate 10. And fixed in a state of protruding downward, and a pair of oil-impregnated bearings 16 and 18 are provided inside the sleeve 14.
The shaft 20 is rotatably supported via. The upper and lower ends of the shaft 20 are led out from the sleeve 14 in the vertical direction.

A stator 26 formed by winding a coil 24 around a stator core 22 is fixed to the outer periphery of the lower half of the sleeve 14, and the stator 2 is attached to the lower end of the shaft 20.
A cup-shaped rotor holder 28 arranged so as to surround the outer periphery of 6 is fixed by caulking or the like.
An annular rotor magnet 30 is fixed to the inner peripheral surface of the cylindrical wall. The rotor magnet 30 faces the outer peripheral surface of the stator 26 with a slight gap. A rotor 32 is constituted by the rotor holder 28 and the rotor magnet 30.

At the upper end of the shaft 20, a turntable 34 located above the substrate 10 is press-fitted and fixed, and a CD (recording medium) not shown is placed on the turntable 34. A sensor 36 including one Hall element is arranged at a position corresponding to the rotor magnet 30 on the lower surface of the substrate 10 and detects the magnetic flux of the rotor magnet 30.

FIG. 3 shows the relationship between the stator 26 and the rotor 32 in the micromotor. The coil 24 is omitted.

The stator core 22 of the stator 26 has a six-slot structure made of a unidirectional silicon steel plate, and six teeth (,,, ...) 38 are arranged at equal intervals in the circumferential direction. The magnetization direction of the stator core 22, that is, the direction of the easy axis of magnetization, is set to any one tooth () 3
8 has a deviation angle θ (about 10 degrees) with respect to the protruding direction. This declination θ has the effect of doubling the angle from the relationship of the electrical angle based on the number of slots of the stator core 22.

Each tooth (,,, of the stator core 22
,,,) 38 have coils (,,,)
,,,) 24 are wound, but these coils (,,,,,) 24 are, as shown in FIG. 1, a series circuit of three coils (,,) 24 and three coils (,,,). ) 24 series circuits are connected in parallel to form one circuit network 40. In this case, each coil (,,,,,) 24 is set to have the same number of turns, but the winding directions of the two coils (,) and the other coils (,,,) 24 are different, and therefore the number of turns is increased. The number of magnetic coils and the number of demagnetizing coils are different. In FIG. 1, R1, R2 (R
1 = R2) indicates the DC resistance of the coil.

On the other hand, the rotor magnet 30 has an 8-pole structure, and N poles and S poles are alternately arranged in the circumferential direction to form eight magnetic poles. Note that, in addition to 8 poles, 4 poles (not shown) can be used, and good motor characteristics equivalent to or better than those of 8 poles can be obtained. The sensor 36 is
On the lower surface of the substrate 10, the rotor core 30 is arranged radially outside the center between any two adjacent teeth (,) 38 of the stator core 22.

FIG. 4 shows a schematic configuration of the motor control circuit 42. The motor control circuit 42 is connected to a DC power supply 44 and supplies a DC current to the circuit network 40, and an excitation current control that controls switching of switching elements connected to the circuit network 40, for example, transistors T1 to T4. And a portion 48.

The power supply control unit 46 controls the electric current supplied to the circuit network 40 by the CLV signal obtained when reproducing the CD, and controls the rotation speed of the rotor 32. In addition, the exciting current control unit 48 drives the coils 24 at the same time by bidirectional energization in which the energization direction is reversed while the magnetization of the stator core 22 remains substantially without including a rest period, and is formed by energization. The coil 24 is excited by using the detection signal of the sensor 36 so that the respective electromagnetic poles of the stator core 22 collectively generate a rotational force with respect to the opposing magnetic poles of the rotor magnet 30.

In the thus constructed micromotor, when the motor control circuit 42 drives the circuit network 40 by the coils 24 of the stator 26, the stator core 22 has a directional property, so that the magnetic flux path in the motor is increased. The sensor voltage is obtained by the displacement of the motor, and the motor starts without a dead center. After starting, each tooth 38 of the stator 26 has a coil (,) 24 and a coil (,,,
) 24, the rotor 32 is magnetized in accordance with the winding direction, so that a rotational force is generated according to the difference in the generated magnetizing force, and the rotor 32 accelerates quickly even if there is non-energized cogging.

When the rotor 32 is started, the sensor 36 detects the rotational position of the rotor magnet 30, that is, the boundary between the magnetic poles, and the detection signal directly or after delaying the signal switches the energizing direction to the network 40. Electromagnetic poles having a polarity opposite to that of the opposing magnetic poles of the rotor magnet 30 are formed on the teeth 38.
It is possible to continuously apply the rotational force to the two.

In particular, in this embodiment, when the rotor 32 is de-energized, the magnetic poles of the rotor magnet 30 face the tips of the stator core 22, respectively.
When the stator core 22 is magnetized by energizing the coil 24 at the time of start-up, the magnetization center of each tip deviates from the center of the tip by a deviation angle θ.
The center of each magnetic pole and the magnetization center of each tip 40 are deviated, and a rotational force based on these deviation angles acts on the rotor magnet 30, and the rotor 32 is quickly activated.

In the conventional brushless motor, a 3-phase bipolar is mainly used. In this case, if 6 slots are set at a certain time, only 4 slots are energized and 2 slots are stopped. . Therefore, the rotor 1
For rotation, magnetomotive force is generated from four teeth. On the other hand, in the present invention, since magnetomotive force is generated from 6 teeth per one rotation, rapid acceleration / deceleration can be realized with the ratio of the torque output.

FIGS. 5 and 6 show a second embodiment showing the case of 12 poles and 9 slots. The stator core 52 of the stator 50 has a nine-slot configuration, and nine teeth (,,,,,,) 54 are arranged at equal intervals in the circumferential direction, that is, at 40-degree intervals. Each of the teeth (,,,,,,,) 54 has a coil (,,,,,,,,).
) 56 is wound, but these coils (,,
,,,,,,) 56 is one coil (') 5 when four coils (,,,,) 56 and one coil () are bisected as shown in FIG.
6 series circuits and 4 coils (,,,) 56
And a series circuit of the other coil (″) 56 when one coil () is divided into two equal parts are connected in parallel to form one circuit network 58.

In this case, each coil (,,,,
,,,,) 56 are set to have the same number of turns respectively, but the winding directions of the four coils (,,,) 56 and the five coils (,,,,) 56 are different, and thus the coil of increased magnetism is used. The number and the number of demagnetizing coils are different. In FIG. 6, R1
1, R12 (R11 = R12) represents the DC resistance of the coil.

On the other hand, the rotor 60, which is rotatably provided so as to face the stator 50, is constructed by attaching an annular rotor magnet 62 to the inner peripheral surface of the peripheral wall of the rotor holder. The rotor magnet 62 has a 12-pole configuration, and N poles and S poles are alternately arranged at equal intervals in the circumferential direction. In addition to 12 poles, 6 poles (not shown) can be used, and good motor characteristics equivalent to or better than 12 poles can be obtained. A sensor 64 such as a Hall element is arranged so as to face the rotor magnet 62.

In the micromotor constructed as described above, when the circuit network 58 of the coils 56 is driven by the motor control circuit as in the case of the first embodiment, the teeth 54 of the stator core 52 are coil(,,
,) 56 and the coils (,,,,) 56 are magnetized in accordance with the winding direction, a rotational force is generated according to this difference, and the rotor 60 quickly starts rotating even if there is non-energized cogging. In the present embodiment, since the number of slots is large, the non-energized cogging is reduced especially in combination with the directional stator. Further, during rotation, high torque is obtained in proportion to the number of poles.

When the rotor 60 starts rotating, the sensor 64 detects the rotational position of the rotor magnet 62, that is, the position of the magnetic pole, and the detection signal outputs the circuit network 58.
By switching the energizing direction to the rotor 60, it becomes possible to continuously apply the rotational force to the rotor 60, and thereafter, the rotation of the rotor 60 is continued.

Next, third to fifth embodiments of the present invention will be described with reference to FIGS. In addition, these examples are
Similar to the case of the first embodiment, a case where a stator having a 6-slot structure is used is shown.

First, in FIG. 7 showing the third embodiment, six coils (,,,,,) 70 wound around each tooth of the stator are connected in series to form one coil.
Although one circuit network 72 is configured, three coils (,
,) 70 and the three coils (,,) 70
The number of turns is different and the winding direction is different, and the sums of the magnitudes of the magnetizing component and the demagnetizing component of the magnetic flux generated by energizing each coil 70 are different.

In FIG. 8 showing the fourth embodiment, the six coils (,,,,,) 80 wound around each tooth of the stator are connected in parallel to form one coil.
One circuit network 82 is formed, and each coil (,,,
,,,) 80 have the same number of turns, but two coils (,) 80 and four coils (,
,,) 70 and the winding directions are different from each other, and the numbers of magnetizing and demagnetizing are different.

Further, in FIG. 9 showing the fifth embodiment, the six coils (,,,,,) 90 wound around each tooth of the stator are all set to the same number of turns, and Three coils (,,) 90
And the three coils (,,) 90 have winding directions opposite to each other, but the coils (,) 90 are connected in parallel and connected in series to the coil () 90, and the coils (,) 90 are connected in parallel. They are connected and connected in series to the coil () 90, and these series circuits are connected in parallel to form a so-called series-parallel circuit.

Therefore, half of the drive current from the motor control circuit is supplied to the coil (,) 90.
,) 90 is supplied with a quarter of the drive current from the motor control circuit, and as a result, the sum of the respective magnitudes of the magnetic flux increasing and demagnetizing components generated by the energization of each coil 90 is calculated. Is different.

By connecting the coils in series and parallel in this way, it becomes possible to cope with various power source voltages with a similar motor structure. Further, it is possible to deal with different rotation speeds by changing the terminal voltage of each tooth coil.

Although various embodiments of the brushless motor according to the present invention have been described above, the present invention is not limited to these embodiments, and various changes and modifications are made without departing from the scope of the present invention. It goes without saying that modifications are possible.

For example, when the series-parallel circuit is composed of each coil, the number of series coils or the number of parallel coils is changed, and the magnitudes of the magnetic demagnetization component and the magnetic demagnetization component of the magnetic flux generated by energizing each coil are different. The sum of may be different.

Alternatively, the wire diameter of each coil may be made different so that the sum of the respective magnitudes of the magnetizing component and the magnetizing component of the magnetic flux generated by energizing each coil may be made different. Alternatively, the magnitude of the generated magnetomotive force may be changed by changing the ampere-turn according to the directionality of each tooth.

Although the outer rotor type brushless motor has been described in the above embodiment, it is apparent that the same can be applied to the inner rotor type brushless motor.

[0043]

Since the present invention is configured as described above, the following effects can be obtained. Each coil wound around each tooth to form one circuit network and simultaneously excited by bidirectional energization by a single-phase power source has respective magnitudes of the magnetic flux increasing and demagnetizing components. By making the sums different, at least a part of the non-energized cogging can be canceled by the magnetomotive force due to the difference in the magnitudes of the magnetizing component and the demagnetizing component, and high starting reliability is achieved even when the non-energizing cogging is present. It is possible to provide a novel brushless motor that can obtain high performance, has less rotation unevenness, and can obtain high torque.

In addition, in order to avoid non-energized cogging, there is a complicated relationship such that the number of slots in the stator and the number of magnetic poles in the rotor magnet have a special relationship, a plurality of sensors are used, or an auxiliary pole is provided in the stator. It is possible to provide a simple, small-sized, inexpensive brushless motor without requiring any special structural ingenuity.

[Brief description of drawings]

FIG. 1 is a wiring diagram of a circuit network including coils according to a first embodiment of a brushless motor of the present invention.

FIG. 2 is a cut front view showing the overall configuration of the brushless motor of FIG.

FIG. 3 is a plan view of a stator and a rotor showing a main part of the brushless motor of FIG.

FIG. 4 is a circuit diagram showing the coil drive circuit of FIG.

FIG. 5 is a plan view of a stator and a rotor showing a main part of a second embodiment of the present invention.

FIG. 6 is a wiring diagram of a circuit network formed by the coils of FIG.

FIG. 7 is a wiring diagram of a circuit network including coils according to a third embodiment of the present invention.

FIG. 8 is a wiring diagram of a circuit network including coils according to a fourth embodiment of the present invention.

FIG. 9 is a wiring diagram of a circuit network including coils according to a fourth embodiment of the present invention.

[Explanation of symbols]

 22, 52 Stator core 24, 56, 70, 80, 90 Coil 26, 50 Stator 30, 62 Rotor magnet 36, 64 Sensor 40, 58, 72, 82, 92 Circuit network

Claims (6)

[Claims] 1. A stator configured by winding a coil around each tooth of a stator core having a plurality of slots, and a stator rotatably opposed to the stator and having different poles alternately arranged in the circumferential direction. A brushless motor comprising: a rotor magnet formed by: and a sensor for detecting a magnetic flux of the rotor magnet, wherein each coil wound around each tooth forms one circuit network, and the circuit network is a single network. The sum of the magnetizing component and the demagnetizing component of the magnetic flux generated by the energization of the coils is different from each other, and the sum of the magnetizing component and the demagnetizing component is different. A brushless motor characterized in that at least a part of non-energized cogging is canceled by a magnetomotive force due to a difference in size between the and. 2. The brushless motor according to claim 1, wherein polarities of the coils wound around the teeth are different in the number of magnetizing and demagnetizing. 3. The number of turns of each of the coils wound around each of the teeth is different between magnetizing and demagnetizing.
Brushless motor described. 4. Each of the coils wound around each of the teeth is connected in series or in parallel for increasing magnetism and demagnetizing,
The brushless motor according to claim 1, further comprising a coil in which wire diameters of the magnetizing winding and the magnetizing winding are different. 5. The brushless motor according to claim 1, wherein the stator core or the rotor magnet has directionality with respect to its magnetization. 6. The brushless motor according to claim 1, wherein the exciting current to the coil is performed at the time of reverse excitation in which the energization direction is reversed without including a pause period that is sufficiently long compared to the magnetic aftereffect time of the stator core. .