JPH0815384B2 - Single-phase brushless motor - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a single-phase brushless motor whose output can be changed over a wide range and whose torque ripple is small.

[Conventional technology]

Brushless motors are widely used in various information devices, machine tools, etc. due to their characteristics of long life and high reliability. With this structure, the magnetic pole position of the rotor magnet is detected by a magnetic sensor such as a Hall element, and based on this result, the energization of the stator coil is switched to obtain a rotary motion. However, it is a drawback of brushless motors that the magnetic sensors and the electronic circuits for switching are expensive.

The cost of the magnetic sensor and the electronic circuit is reduced by reducing the number of energized phases, and the cost is reduced by using a single phase.
However, simply making a single phase results in a motor having a so-called dead center in which the output torque becomes 0 at a certain rotation angle, which is not suitable for practical use.

U.S. Pat.
The methods described in the specification are well known. This method generates a reluctance torque by changing the air gear gap between the rotor and the stator,
This is a method of eliminating the dead center by superimposing this and the torque due to energization. This principle is shown in FIG.

In FIG. 9, (a) shows a torque curve generated by energization, and the point of x is the dead point. (B) is a reluctance torque curve, and when the reluctance torque curve (b) is overlaid on the torque curve (a), a combined torque curve (c) is obtained, and there is no dead point and torque characteristics with less torque ripple. Is obtained.

[Problems to be solved by the invention]

The drawback of the above method is that a large torque ripple occurs when the output is changed. That is, when the output is increased, the torque curve (d) in FIG. 9 is obtained, and when the output is decreased, the torque curve (e) is obtained. In both cases, the torque ripple increases, and when the output is further decreased, the torque curve (e) is obtained. As in the case of f), there is a problem that the reverse torque T _C is generated and normal operation becomes impossible.

The present invention has been made to solve the above problems, and an object of the present invention is to provide a single-phase brushless motor that has low torque ripple and high efficiency over a wide range of output at low cost.

[Means for solving problems]

The single-phase brushless motor according to the present invention has a rotor
The 2m pole first magnetized part and the 4m pole second magnetized part are provided, and the magnetic force of both magnetized parts becomes zero. Rotation is made different, and on the other hand, the unit is A, A ', B, B'wound on the stator at an open angle corresponding to the second magnetized portion.
l stator coils are provided, and 2l of the 4l stator coils A and A'or B and B'are alternately arranged so that the stator coils A and B are in the same direction and A'and B '.
Is designed to be energized in the opposite direction.

[Action]

In the present invention, the point that the 2l pieces are alternately energized to the 4l pieces of the stator coils, and the magnetic forces of the first and second magnetized parts become zero. Since it is rotated, the torque ripple is suppressed.

〔Example〕

1 (a) and 1 (b) are plan views of a stator and a rotor showing an embodiment of the present invention.

FIG. 1 (a) shows a stator, 1 is a stator coil, wound at an opening angle of 45 °, 4 l pieces, that is, l in this example.
= 2, eight are provided. 2 is a yoke. Three
Is a Hall element, which detects the magnetization component of the magnetic pole described later.
4 is a bearing housing, 5 is a bearing, 6 is a shaft, and the shaft side is attached to the shaft 6.
It is rotatably supported by a bearing 5.

FIG. 1B shows a rotor, 7 is a yoke, 8 is a magnetic pole, and is provided with a first magnetized portion 81 of 2 m pole and a second magnetized portion 82 of 4 m pole. In this example, m = 2 and 4
It is magnetized with 8 poles and 8 poles, and this is attached to the shaft 6 through the yoke 7 as described above. Second
The boundary of the pole on the side of the magnetized part 82 is 22.5 ° relative to the boundary of the pole on the side of the first magnetized part 81 Only the rotation is different.

Next, the operation will be described. When the rotor rotates and the pole of the magnetic pole 8 faces the Hall element 3, the Hall element 3 detects this. The stator coil 1 is energized based on the detection result. When the stator coil 1 is divided into A, A ', B and B'as shown in Fig. 1 (a), this energization is switched alternately to A and A'or B and B'and A and A ', B and B'are energized by reversing the energizing directions.

A combination of the magnetic fluxes generated from the first magnetized portion 81 and the second magnetized portion 82 becomes a curve shown in FIG. The magnetic flux distribution is such that the N pole of the first magnetized portion 81 is canceled by the S pole of the second magnetized portion 82 at both ends, and the S pole of the first magnetized portion 81 is in the center. This is because it is canceled by the N pole of the second magnetized portion 82. The magnetic flux distribution as described above can be obtained by changing the magnetization width of the N pole and the S pole. A lot
Even in this case, the portion detected by the Hall element 3 is the portion of the first magnetized portion 81.

FIG. 3 shows a torque curve when the stator coil 1 is energized, and (a) shows A of the stator coil 1.
And A'is energized, and (b) is the same when B and B'are energized. It should be noted that the dotted line shows the torque generated if it is not energized. As can be seen from this, the range in which the positive torque is generated is 180 ° or more, and by switching the energization at the position x shown in the figure, a characteristic without a dead center can be obtained.

Next, the principle of suppressing torque ripple will be described with reference to FIG. When the magnetic poles 8 of the rotor shown in FIG. 1 (b) are developed in the circumferential direction, the first magnetized portion is obtained as shown in FIG. 4 (i).
This corresponds to the formation of 81 and the second magnetized portion 82.
Now, temporarily, as shown in FIG. 4 (ii), the coil 1 wound at an opening angle corresponding to the first magnetized portion 81 and the second magnetized portion 82.
And the coil II wound at an open angle corresponding to When comparing the torque generated in this configuration with the conventional example of FIG. 9, the torque generated in the coil I is 9
This corresponds to the torque curve (a) in the figure, and the torque generated in the coil II also corresponds to the torque curve (b). Conventional torque curve (b) is constant irrespective of the fluctuation of the output mediation by reluctance torque, to have changed by only output torque curve (a), the backward torque T _C as a torque curve (f) It will occur, but Fig. 4 (ii)
The torque generated in the coil II does not generate the reverse torque T _C for changing like the torque generated in the coil I.

As shown in FIG. 4 (ii), when a current is applied to the coils I and II in the directions shown by the arrows, a coil in which torque is canceled and a coil that joins the coils are formed. As a result, in FIG. 4 (iii) Coil I
It is equivalent to providing only II. Furthermore, Fig. 4 (iv)
As shown in FIG. 4 (ii), a direct current in the same direction as that shown in FIG. 4 (ii) is applied to the coil II, and the energizing direction of the coil I is reversed. It is equivalent to the provision. Therefore, Fig. 4 (iii) and (v)
And the coils A, A ', B, B'as shown in Fig. 4 (vi).
It suffices that a current be supplied in the direction shown in FIG. These coils A, A ', B, B'are the same as those shown in FIG. 1 (a).

In FIG. 4 (ii), there is no problem because the actions of the coil I and the second magnetized portion 82 and the action of the coil II and the first magnetized portion 81 are canceled out.

FIG. 5 shows the torque characteristics of the embodiment shown in FIG. 5 (a) to (f) correspond to FIGS. 9 (a) to (f), and FIG. 5 (a) shows the first magnetizing portion 81 and the stator coil 1. The generated torque curve, (b) is the second magnetized portion 82
Shows the torque characteristics at the rated output, (d) at 1.5 times output, (e) at 0.7 times output, and (f) at 0.3 times output. ing.
As is apparent from comparison with FIG. 9, according to the present invention, the torque ripple does not increase even if the output is changed.

FIG. 6 shows an example of the drive circuit used in the present invention. In this FIG., 3, A, A ', B, B' is the same as that shown in FIG. 1, Q ₁ to Q ₃ are transistors, R ₁ to R ₃ resistors, T is is a control terminal .

The operation will be described. When the first magnetized portion 81 comes to a position facing the hall element 3 due to the rotation of the rotor, the hall element 3 outputs. This output is the transistor Q ₁ , Q ₂
Is differentially amplified by and the coils A and A'are energized. When the rotor further rotates and the next first magnetized part 81 faces the hall element 3, the polarity of the first magnetized part 81 at this time is opposite to that of the previous time, so the direction of the electromotive force of the hall element 3 is also changed. The opposite, A,
The energization is switched from the A'coil to the B and B'coils.
The magnitude of the energizing current is controlled by the base current applied from the control terminal T.

Although the above embodiment is a case of the coreless type flat motor, the present invention is not limited to the radial gear type motor,
It can also be applied to a core type motor. An example thereof will be described with reference to FIG.

FIG. 7 shows another embodiment of the present invention, which is a radial gear type. Reference numeral 2'denotes a core, and the others are the same as in FIG. Development views of the magnetic pole 8 in the case of this embodiment are shown in FIGS. 8 (a) to 8 (c).

FIG. 8 (a) shows a first magnetized portion 81 having a 2 m pole and a second magnetized portion 82 having a 4 m pole formed in the axial direction of the shaft 6. In FIG. The magnetic part 81 is displayed. The dotted circle 3'indicates the position of the Hall element 3.

FIG. 8 (b) shows an embodiment in which the north and south poles of the cancell portion in FIG. 8 (a) are notched.

Further, FIG. 8 (c) shows an embodiment in which the first and second magnetized portions 81 and 82 are overlapped and magnetized, that is, the magnetized width is changed, and the magnetic flux distribution shown in FIG. To obtain N pole, S
The width of the pole is changing. In the case of this embodiment, it is necessary that the Hall element detection portion has the same width for the N pole and the S pole.

In the case of the core type motor shown in FIG. 7, the cogging due to the magnetic attraction force between the magnetic pole 8 and the core 2'causes uneven rotation, but in the case of the present invention, the magnetization component of the first magnetized portion 81. Then, the cogging torques caused by the magnetization component of the second magnetized portion 82 cancel each other out, and torque characteristics with less torque ripple are obtained.

〔The invention's effect〕

As described above, the present invention has a rotor with a 2 m pole first
The magnetizing part of and the second magnetizing part of 4m pole are provided, and the point where the magnetic force of both magnetizing parts becomes zero Rotation is made different, and on the other hand, the unit is A, A ', B, B'wound on the stator at an open angle corresponding to the second magnetized portion.
l stator coils are provided, and 2l of the 4l stator coils A and A'or B and B'are alternately arranged so that the stator coils A and B are in the same direction and A'and B '.
Since it is configured to drive by energizing in the opposite direction to this, there is an advantage that torque characteristics without torque ripple can always be obtained regardless of increase or decrease in output.

[Brief description of drawings]

1 (a) and 1 (b) are plan views of a stator and a rotor showing an embodiment of the present invention, FIG. 2 is a view showing a distribution state of magnetic flux in the embodiment of FIG. 1, and FIG. 1 is an explanatory view of torque characteristics in the embodiment, FIG. 4 is a drawing for explaining the principle of torque ripple suppression of the present invention, FIG. 5 is a torque characteristic drawing of the present invention, and FIG. 6 is a drive used in the present invention. FIG. 7 shows an example of a circuit, FIG. 7 is a sectional view showing another embodiment of the present invention, and FIGS. 8 (a), (b), and (c) are development views of magnetic poles in the embodiment of FIG. FIG. 9 shows various examples, and FIG. 9 is a torque characteristic diagram of a conventional single-phase brushless motor. In the figure, 1 is a stator coil, 2 is a yoke, 3 is a Hall element, 4 is a bearing housing, 5 is a bearing, 6 is a shaft, 7 is a yoke, 8 is a magnetic pole, 81 is a first magnetized portion,
Reference numeral 82 is a second magnetizing portion.

Claims (1)

[Claims] 1. A magnetic pole having a first magnetized portion of 2 m pole and a second magnetized portion of 4 m pole, and the point where the magnetic force of both magnetized portions becomes zero is different by 1/8 m rotation. Rotor, and 4 l stator coils in units of A, A ', B, B'wound at open angles corresponding to the second magnetized portion arranged via the magnetic pole and the air gap , A magnetic pole detecting element provided on the stator for detecting the magnetization component of the first magnetizing portion, and 2l of A and A'or B and B'of the stator coil based on the detection result of the magnetic pole detecting element. A single-phase brushless motor, characterized in that the stator coils A and B are alternately provided in the same direction, and the stator is provided with an electronic circuit for energizing A'and B'in the opposite direction. . However, m and l are integers of 1 or more, and l ≦ m.