JPH02237453A - Dc brushless motor - Google Patents

Abstract

PURPOSE:To reduce the number of parts and lead wire and to facilitate assem bling work by providing a magnetizing section for varying the flux emitted from the magnetic poles having same polarity in the permanent magnet of rotor and received by a magnetoelectric converting element during rotation of rotor. CONSTITUTION:A rotor 10 is supported rotatably on a bearing device and perma nent driving magnets N, S are fixed thereto. Magnetized sections 5 are formed on the permanent magnets N, S of the rotor 10 so that the flux to be received by a magnetroelectric converting element 3 from magnetic poles of the perma nent magnets N, S having same polarity is varied during rotation of the rotor 10. By such arrangement, a plurality of output voltages are detected from the magnetic poles of the permanent magnets N, S having same polarity during rotation of the rotor 10.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention detects the rotational position of the rotor using a magneto-electric transducer, and uses this detection output to switch the drive current to the stator coil group to generate a rotating magnetic field to drive the rotor. The present invention relates to a brushless DC motor that can reduce the number of required magnetoelectric conversion elements in a motor that rotationally drives a motor.

[Prior Art] A brushless DC motor that detects the rotational position of the rotor using a magneto-electric conversion element and uses this detection output to switch the drive current to the stator coil group to generate a rotating magnetic field and rotate the rotor is a three-phase, four-phase motor. In the case of poles, conventionally, Figures 6 and 7
As shown in the figure, three magnetoelectric conversion elements (for example, Hall elements) 3, 3, 3, for detecting the rotational position of the rotor 2 are arranged in the stator core 1 at an electrical angle of 240 m from each other, and these magnetoelectric transducers are Detection output of conversion element 3?32,3? Based on the three-phase stator coil Ue and u2
, v1 and v2, w2 and w2 are switched to generate a rotating magnetic field, thereby rotating the rotor 2. That is, as shown in FIG. 8, the electrical angle is O~
60'', the detection outputs of the magnetoelectric transducers 3, 3, and 3 become H.L.H, and based on these detection outputs, U
Flow the driving current from the terminal to the V terminal, and the electrical angle is 60 to 1
200, 3■, 3-3, is H. L. L, and the driving current flows from the U terminal to the W terminal, and the electrical angle is 120
~180°, 3-3■, 3, is H. H. L, the drive current I flows from the V terminal to the W terminal, and the electrical angle is 1.
When the angle is 80 to 240 degrees, 32,3, is L. H. L
When the electrical angle is 240 to 300', the driving current flows from the V terminal to the U terminal, and 3■, 3, 3, are L.
H, H and the drive current flows from the W terminal to the U terminal,
When the electrical angle is 300 to 3601, 3.3. , 33 is L,L. H, a driving current flows from the V terminal to the W terminal to generate a rotating magnetic field, causing the rotor 2 to rotate in the clockwise direction shown by the arrow. [Problems to be Solved by the Invention] However, in the conventional brushless DC motor shown in FIGS. 6 and 7, in the case of a three-phase four-pole motor, three expensive magnetoelectric conversion elements are required, resulting in a large number of parts. At the same time, there were problems in that the number of leader lines increased, making assembly complicated and expensive. The present invention has been made in view of the above-mentioned problems.
The purpose of the present invention is to provide a brushless DC motor that can reduce the number of required magnetoelectric conversion elements, reduce the number of parts, reduce the number of lead wires, and be easy to assemble and inexpensive. It is something. [Means for Solving the Problems] The present invention detects the rotational position of a rotor equipped with permanent magnets using a magneto-electric conversion element, and uses this detection output to switch the drive current to the stator coil group to generate a rotating magnetic field. In a brushless DC motor configured to rotationally drive a rotor, a magnetic flux changing device is attached to a permanent magnet of the rotor to change the magnetic flux that the magnetoelectric conversion element receives from magnetic poles of the same polarity of the permanent magnet of the rotor when the rotor rotates. It is characterized by forming a magnetic part.

[Function] The magnetic flux changing magnetized part formed on the permanent magnet of the rotor is formed so as to change the magnetic flux that the magnetoelectric transducer receives from magnetic poles of the same polarity of the permanent magnet of the rotor when the rotor rotates. Therefore, the detection outputs detected by the magnetoelectric transducer from magnetic poles of the same polarity of the permanent magnets of the rotor when the rotor rotates are a plurality of output voltages having different voltage levels. Based on a plurality of eight detected voltages having different voltage levels detected by such a magneto-electric conversion element, the drive current to the stator coil group is switched, a rotating magnetic field is generated, and the rotor is rotationally driven.

[Example] An embodiment of the present invention will be described below with reference to the drawings.

1, 2, and 3 show an embodiment of the present invention, and in these figures, FIGS. 6, 7, and 8.
Parts that are the same as those in the figures are given the same reference numerals.

1 and 2, reference numeral 10 denotes a rotor rotatably supported by a bearing device and to which permanent magnets N and S for driving are attached. A stator core 1 is provided around the rotor 10, and the stator core 1 includes three-phase stator coils u4 and u2 having an electrical angle of 240 degrees.
VL, V, W, and w2 are provided, and a magnetoelectric transducer (for example, a Hall element) 3 for detecting the rotational position of the rotor 10 is also provided. Permanent magnet N. of the rotor 10 Each of S has a distance G and G with respect to the magnetoelectric conversion element 3 when the rotor 10 rotates.
A magnetized part 5 for changing magnetic flux is formed of a stepped magnetized part changed in three steps: 2, G, (G1<G2<G3). Next, the operation of the above embodiment will be explained with reference to FIG. 3. (a) When the electrical angle is from 0 to 180 degrees,
The magnetic pole of the magnetic flux changing magnetized portion 5 facing the is N.

When the electrical angle is O-60'', the distance G1 between the magnetic flux changing magnetized part 5 and the magnetoelectric conversion element 3 is the smallest, so
The magnetic flux received by the magnetoelectric conversion element 3 becomes the largest, and its detected output voltage becomes the largest a (V). Moreover, when the electrical angle is 60 to 120 degrees, the distance between the magnetic flux changing magnetized part 5 and the magnetoelectric conversion element 3 is G2, which is larger than Ge.
The detected output voltage of the magnetoelectric conversion element 3 changes to b(v) which is smaller than a(v). Furthermore, the electrical angle is 120 to 180
°, the distance between the magnetized part S for magnetic flux change and the magnetoelectric transducer 3 is G, which is larger than G2, so the magnetoelectric transducer 3
The detected output voltage of changes to c(v), which is smaller than b(v). (Example) When the electrical angle is 180 to 360", the magnetic pole of the magnetized part 5 for magnetic flux change facing the magnetoelectric conversion element 3 is S. When the electrical angle is 180 to 2400", the magnetic pole for magnetic flux change is S. Since the distance G3 between the magnetized part 5 and the magnetoelectric transducer 3 is the largest, the detected output voltage of the magnetoelectric transducer 3 is c (v
) changes to a smaller d (v). Also, the electrical angle is 2
40 to 300', the distance between the magnetic flux changing magnetized part 5 and the magnetoelectric transducer 3 is G, which is smaller than G2, so the detected output voltage of the magnetoelectric transducer 3 is e, which is smaller than d (v).
Changes to (■). Furthermore, the electrical angle is 300-360"
When , the distance between the magnetized part 5 for magnetic flux change and the magnetoelectric transducer 3 is G, which is smaller than G1, so the detected output voltage of the magnetoelectric transducer 3 changes to f (v), which is smaller than e (v). do. (c) As mentioned above, the detected output voltage of the magnetoelectric transducer 3 is a
．． b, c. d. e, f, these detected power voltages a, b. c. d, e. Based on f, S, stator coil Ue and u2, Vl and v2, w1 and w2
The flow of drive current I flowing through U is from the U terminal to the V terminal.
From terminal to W terminal, ■Terminal to W terminal, ■Terminal to U
The terminals are sequentially switched from the W terminal to the U terminal, and from the W terminal to the V terminal, generating a clockwise rotating magnetic field and rotating the rotor 10 in the clockwise direction, which is the original rotation direction.

In the above embodiment. Although the magnetic flux changing magnetized portion formed on the permanent magnet of the rotor is a step-like magnetized portion in which the distance from the magnetoelectric conversion element is changed in multiple steps (for example, three steps), the present invention is limited to this. Any magnetized part may be used, as long as the magnetoelectric transducer changes the magnetic flux received from the same magnetic pole of the permanent magnet of the rotor when the rotor rotates. For example, as shown in FIG. 4, permanent magnet N. A magnetic flux changing magnetized part 5a whose end face facing the magnetoelectric transducer 3 along the rotational direction of the rotor 10a has a sinusoidal shape is formed in a part of S, and the magnetic flux changing magnetized part 5a is formed in a part of the magnetoelectric transducer 3 when the rotor 10a rotates. The interval may be changed continuously. Or as shown in Figure 5. The distance G between the rotor 10b and the magnetoelectric transducer 3 during rotation is constant, and the permanent magnet N of the rotor 10b is fixed. A magnetized part for changing the magnetic flux is provided in each part of the rotor 10b so that the magnetic flux density of the part facing the magnetoelectric transducer 3 along the rotational direction of the rotor 10b has three levels (for example, three levels of 1000, 800, and 600 Gauss). form sb, i.e.
The magnetic flux changing magnetized part 5b is formed by a magnetized part in which the magnetized distribution along the rotational direction of the rotor 10b is changed in multiple stages, so that the magnetic flux that the magnetoelectric conversion element 3 receives from magnetic poles of the same polarity is changed. You can. In the above embodiment, the number of magnetoelectric transducers facing the magnetic flux changing magnetized portion of the permanent magnet of the rotor is one, but the present invention is not limited to this. A plurality (for example, two) of facing magnetoelectric conversion elements may be used. In the embodiment described above, the permanent magnet for causing the magneto-electric conversion element to detect the rotational position of the rotor is a driving permanent magnet attached to the rotor, and a part of this driving permanent magnet is provided with a magnetized part for changing the magnetic flux. However, the present invention is not limited to this, and the permanent magnet for causing the five magnetoelectric conversion elements to detect the rotational position of the rotor is a permanent magnet for position detection attached to the rotor, and the permanent magnet for detecting this position is attached to the rotor. A magnetic flux changing magnetized portion may be formed on the detection permanent magnet.

Although the present invention is applied to a 3-phase 4-pole inner rotor type brushless DC motor in the Moeki embodiment, the present invention is not limited to this, and may be applied to a 2-phase type or 4-phase type, for example. Therefore, an inner rotor type or outer rotor type brushless DC motor can also be used.

In the above embodiment, a case was explained in which the magnetoelectric conversion element was used in a motor provided on the stator core side.
The present invention is not limited to this. For example, in the case of an outer rotor type brushless DC motor used for a floppy disk drive, a magnetoelectric conversion element may be provided on the housing side. [Effects of the Invention] As described above, the brushless DC motor according to the present invention has the following features.
A magnetized part for changing the magnetic flux is formed on the permanent magnet of the rotor, and when the rotor rotates, the magnetoelectric transducer changes the magnetic flux received from the magnetic poles of the same polarity of the permanent magnet of the rotor. Since the configuration is configured so that the detection outputs detected from the magnetic poles of the same polarity of the magnet are multiple output voltages with different voltage levels, the level of the detected output voltage can be maintained without changing the magnetic flux received from the magnetic poles of the same polarity of the permanent magnet of the rotor. Compared to the conventional example in which there is only one magnetoelectric conversion element, it is possible to increase the level of the detection output voltage that the magnetoelectric conversion element detects from the magnetic poles of the same polarity of the permanent magnet of the rotor. Therefore, the number of magnetoelectric transducers required to detect the rotational position of the rotor can be reduced compared to conventional methods, reducing the number of parts and lead wires, making assembly easier and reducing costs. It can be made cheap.

[Brief explanation of drawings]

1, 2, and 3 show an embodiment of the brushless DC motor according to the present invention. FIG. 1 is an explanatory diagram for explaining the main parts of the present invention, and FIG. 2 is a perspective view of the rotor. , 3rd
4 is an explanatory diagram illustrating the main parts of another embodiment. FIG. 5 is an explanatory diagram illustrating the main parts of another embodiment. , Figures 7 and 8 show conventional examples, Figure 6 is an explanatory diagram, and Figure 7 shows a conventional example.
The figure is a perspective view of the rotor, and FIG. 8 is a timing chart explaining the operation. DESCRIPTION OF SYMBOLS 1... Stator core, 3... Magnetoelectric conversion element (for example, Hall element), 5, 5a. 5b... Magnetized part for magnetic flux change, 10. 10a, 10b--rotor, N. S...
・Permanent magnet, uu2, Vl. v,. W Yu, w2...
Stator coil, ■... Drive current flowing through the stator coil. 1st fig. Tsuchidenhen Ryo collection 2nd fig.

Claims (3)

[Claims] (1) Brushless direct current that detects the rotational position of a rotor equipped with permanent magnets using a magnetoelectric conversion element, and uses this detection output to switch the drive current to the stator coil group to generate a rotating magnetic field and drive the rotor to rotate. The motor is characterized in that the permanent magnet of the rotor is formed with a magnetic flux changing magnetized part that changes the magnetic flux that the magnetoelectric conversion element receives from magnetic poles of the same polarity of the permanent magnet of the rotor when the rotor rotates. Brushless DC motor. (2) The magnetic flux changing magnetized portion formed on the permanent magnet of the rotor is a step-like magnetized portion in which the distance from the magnetoelectric conversion element is changed in a plurality of steps when the rotor rotates. Brushless DC motor. (3) The brushless DC motor according to claim 1, wherein the magnetic flux changing magnetized portion formed on the permanent magnet of the rotor is a magnetized portion that changes the magnetization distribution in a plurality of stages along the rotational direction of the rotor. .