JPH03103061A - Brushless motor - Google Patents

Abstract

PURPOSE:To suppress irregularities in operating characteristics and speed by providing one magnetic sensitive element, and controlling exciting currents of phases of electromagnets by an origin detector and a position detector. CONSTITUTION:A magnetic sensitive element 32 is provided, and exciting currents to be conducted in phases of an electromagnet 21 are controlled by an origin detector and a position detector of an outer driving circuit. Even if the position of the element 32 is irregular, the timings of the exciting currents to the phases of the electromagnet 21 are not irregular. Therefore, operating characteristics are stabilized. Since one element 32 is provided, the irregularity in the characteristics of the elements 32 do not become a problem as compared with the case of a plurality to improve its reliability. Further, since one element 32 is provided, a speed signal depends only on the magnetizing position of a position detecting magnet 31. Therefore, speed signals of an accurate interval is obtained.

Description

[Detailed description of the invention] [Industrial application field]

The present invention provides a brushless motor that is provided with a position detection magnet that rotates together with a rotating shaft, the position of the magnetic pole of the position detection magnet is detected by a magnetic sensing element, and the excitation current to the electromagnet is controlled based on the position. It is related to.

[Conventional technology]

Generally, this type of brushless motor includes a rotor 1 having a cylindrical rotating magnet 13 fixed to a rotating shaft 11 via a sleeve 12, and a rotor 1 arranged to surround the rotating magnet 13, as shown in FIG. It includes a cylindrical stator 2 made of electromagnets 21 of multiple phases. The electromagnet 21 is formed by winding a coil 24 through an insulating member 23 around an iron core 22 having a plurality of magnetic pole teeth protruding from the surface facing the rotating magnet 13. A position detection magnet 31 separate from the rotation magnet 13 is fixed to the rotation 11flll, and a magnetically sensitive element 32 such as a Hall element is arranged at a fixed position so as to face the magnetic pole of the position detection magnet 31. ing. Therefore, rotor 1
When the position detection magnet 31 rotates, the magnetic sensing element 32 outputs an output voltage corresponding to a change in the amount of magnetic flux generated by the position detection magnet 31 and passing through the magnetic sensing element 32. Based on the output voltage of the magnetically sensitive element 32, the drive circuit controls the excitation current to the coil 24 so that the stator 2 generates a rotating magnetic field. In this configuration, for example, the rotating magnet 13 of the rotor 1
Assume that the electromagnet 21 of the stator 2 has 4 poles, and the electromagnet 21 of the stator 2 has 3 phases.
It is assumed that a bipolar drive is performed by applying a bipolar excitation current to the coil 24. In this case, three magnetic sensing elements 32 are arranged at every 120° in the rotational direction of the rotor 1, and as the quadrotor 1 rotates, the magnetic sensing elements 32 generate voltages as shown in FIGS. 13(a) to 13(e). Outputs . The drive circuit detects the zero point of the output voltage of each magnetic sensing element 32 and generates timing signals as shown in FIGS. 13(d) to (f), and further generates timing signals as shown in FIG. As shown in g) to (i), an excitation current is generated to the coil 24 of each phase. Also, the 13th
As shown in Figure (j), a speed signal is created based on the timing signal.

[Problem to be solved by the invention]

As mentioned above, in the conventional structure, the number of magnetically sensitive elements 32 equal to the number of phases of the electromagnet 21 is required. Therefore, if the positions of the magnetically sensitive elements 32 vary, the timing of the excitation current to the coil 24 varies. This results in variations in product characteristics. Moreover, since a plurality of magnetically sensitive elements 32 are required, each magnetically sensitive element 32
This may lead to a decrease in reliability due to variations in characteristics. Furthermore, when performing speed control by obtaining a speed signal as described above, the magnetic sensing element 3
If there are variations in the positions of 2, the intervals between the speed signals will vary. The present invention aims to solve the above-mentioned problems, and provides a brushless motor that uses one magnetically sensitive element and suppresses variations in operating characteristics and speed due to variations in the position of the magnetically sensitive element. .

[Means to solve the problem]

In the present invention, the above. In order to achieve this purpose, we have developed a quadruple rotor in which rotating magnets magnetized with different polarities alternately in the rotation direction are fixed to a rotating shaft, and a plurality of rotors arranged opposite to the magnetic poles of the rotating magnets to form a rotating magnetic field. A stator consisting of a phase electromagnet, a position detection magnet that is separate from the rotating magnet and fixed to the rotating shaft and magnetized with different polarities alternately in the rotation direction, and a position detection magnet that faces the magnetic poles of the position detection magnet. A magnetically sensitive element is provided at a fixed position, and a drive circuit that controls the excitation current that flows through the electromagnets of each phase based on the output of the magnetically sensitive element. An origin detection section that detects the rotational origin of the rotor based on the output of the rotor, and a position detection section that detects the rotational position of the rotor from the rotational origin based on the output of the magnetically sensitive element are provided. The excitation current applied to each phase of the electromagnet is controlled based on this. The position detection magnet is magnetized to a number of magnetic poles equal to the product of the number of magnetic poles of the rotating magnet and the number of phases of the electromagnet, and is arranged so that the output of the magnetic sensing element for one magnetic pole is distinguished from the output for other magnetic poles. However, it is preferable that the rotation origin is determined based on the output of the magnetically sensitive element at a position facing the one magnetic pole. In order to distinguish one magnetic pole of the position detection magnet from the other magnetic poles, the other end of the yoke, one end of which is opposite to the one magnetic pole, is coupled to the position detection magnet, and the one magnetic pole is connected to one surface of the magnetic sensing element. It is desirable that the one end of the yoke faces the other surface of the magnetically sensitive element at the opposing position. Further, the position detection magnet may be magnetized so that the one magnetic pole has a larger magnetic flux density than the other magnetic pole. Alternatively, the position detection magnet is formed in such a shape that the distance from the magnetically sensitive element at the position where the one magnetic pole faces the magnetically sensitive element is smaller than the distance from the magnetically sensitive element at the position where the one magnetic pole faces the other magnetically sensitive element. You may do so.

[Effect]

According to the above configuration, l magnetically sensitive elements are provided, and the drive circuit detects the rotation origin of the rotor based on the output of the magnetically sensitive elements. and a position detection section that detects the rotational position of the rotor from the rotational origin based on the output of the magnetically sensitive element, and excitation that energizes each phase of the electromagnet based on the rotational origin and the rotational position. Since the current is controlled, even if there are variations in the position of the magnetic sensing elements, there will be no variations in the timing of the excitation current that flows through each phase of the electromagnet, which has the advantage of stabilizing the operating characteristics of the product. There is. In addition, because there is only one magnetically sensitive element, variations in the characteristics of each magnetically sensitive element do not become a problem compared to the conventional configuration in which multiple magnetically sensitive elements are provided.
This improves reliability. Furthermore, the magnetically sensitive element is 1
Although the speed signal is small, the speed signal depends only on the magnetized position of the position detection magnet, so speed signals with accurate intervals can be obtained. The position detection magnet is magnetized to have a number of magnetic poles equal to the product of the number of magnetic poles of the rotating magnet and the number of phases of the electromagnet, and is configured so that the output of the magnetic sensing element for one magnetic pole is distinguished from the output for other magnetic poles. If the rotation origin is determined based on the output of the magnetically sensitive element at the position facing the one magnetic pole, the origin position can be easily detected. In order to distinguish one magnetic pole of the position detection magnet from the other magnetic poles, the other end of the yoke, one end of which is opposite to the one magnetic pole, is coupled to the position detection magnet, and the one magnetic pole is connected to one surface of the magnetic sensing element. If the one end of the yoke is made to face the other surface of the magnetically sensitive element at opposing positions, the magnetically sensitive element will pass through the magnetically sensitive element more at the position where the magnetically sensitive element exists between the one magnetic pole and the yoke than at other positions. Since the amount of magnetic flux increases, a different output can be obtained than when the magnetically sensitive element faces another magnetic pole. Furthermore, even if the position detection magnet is magnetized so that the one magnetic pole has a higher magnetic flux density than the other magnetic pole, the position where the one magnetic pole faces the magnetic sensing element is different from the position where it faces the other magnetic pole. will give different outputs. Alternatively, the position detection magnet is formed in such a shape that the distance from the magnetically sensitive element at the position where the one magnetic pole faces the magnetically sensitive element is smaller than the distance from the magnetically sensitive element at the position where the one magnetic pole faces the other magnetically sensitive element. Even in this case, when one magnetic pole and the magnetic sensing element face each other, a different output can be obtained than when they face the other magnetic pole.

[Embodiment 1] The basic configuration is the same as that of the conventional elliptical, and as shown in FIG. 13 and a cylindrical stator 2 consisting of multi-phase electromagnets 21 arranged so as to surround the stator 13. The sleeve 12 is made of a magnetic material and is fixed to the rotating shaft l1 by press fitting or the like. The rotating magnet 13 has a plurality of poles magnetized so as to alternately have different poles in the rotational direction of the rotor 1, and is fixed to the outer peripheral surface of the sleeve 12 with an adhesive or the like. In addition, rotating magnet l3
is magnetized into a plurality of poles (four poles in this case) at equal intervals.The electromagnet 21 of the stator 2 includes an iron core 22 made by punching and laminating a magnetic material such as a silicon steel plate, and the iron core 22 has a cylindrical shape. A plurality of magnetic pole teeth (six poles in this case) are provided on the inner circumferential surface of the iron core 22 so as to face the rotating magnet 13. Around the iron core 22, an insulating member 23 is formed. The coil 24 is wound through the coil 24.The coil 24 has multiple phases (here, 3 phases).
It is wound so that it becomes (phase). The stator 2 is fixed to the inner circumferential surface of a housing 4 formed in a cylindrical shape with a bottom, and a bearing 41 that pivotally supports one end of the rotating shaft 11 is disposed on the bottom wall. The opening surface of the housing 4 has a bearing stand 4 equipped with a bearing 42 that pivotally supports the other end of the rotating shaft 11.
It is blocked by 3. Further, a detection unit housing 44 is attached to the outer surface of the bearing pedestal 43, and in a space surrounded by the bearing pedestal 43 and the detection unit housing 44, there is a position detection magnet 31 and a magnetically sensitive sensor consisting of a Hall element. element 32;
A wiring board 33 on which a magnetically sensitive element 32 is mounted is delivered. The position detection magnet 31 is separate from the rotating magnet 11, has a disk shape ε, and is fixed to the rotating shaft 11 by press-fitting or adhesive. Also, place. The position detection magnets 31 are magnetized with different polarities alternately in the rotational direction of the rotor 1. The number of poles of the position detection magnet 31 is the same as that of the rotating magnet 1.
It is set equal to the product of the number of magnetic poles of 3 and the number of phases of the electromagnet 21 (that is, 4 poles x 3 phases = 12 poles). The magnetically sensitive element 32 is attached to a substrate 33 by soldering or the like. In addition, a position detection magnet 31 and a magnetic sensing element 32
are separated by a predetermined distance N (for example, 0.511). A signal line 34 is drawn out from the substrate 33, and the output of the magnetically sensitive element 32 is input to a drive circuit described later. By the way, the position detection magnet 31 includes a yoke 35, as shown in FIG. The mounting piece 35a, which is one end of the yoke 35, is fixed to one surface of the position detection magnet 31 in the thickness direction at a portion corresponding to one magnetic pole of the position detection magnet 31 in an overlapping manner. Further, the other end of the yoke 35 is bent into a substantially L shape to form a magnetic pole piece 35b, and the magnetic pole piece 35b faces the one magnetic pole of the position detection magnet 31. York 3
When the one magnetic pole provided with the magnetic pole 5 faces the magnetically sensitive element 32, the magnetically sensitive element 3 is placed between the magnetic pole of the position detection magnet 31 and the magnetic pole piece 35b of the yoke 35, as shown in FIG.
position detection magnet 31 and magnetic pole piece 35 so that
The distance from b is set. Therefore, when the magnetically sensitive element 32 faces the magnetic pole provided with the yoke 35, compared to when it faces another magnetic pole, the magnetically sensitive element 32 faces the magnetic pole provided with the yoke 35.
The amount of magnetic flux passing through 2 will increase. Figure 4 (
The same purpose can be achieved by forming the yoke 35 in the shapes shown in a) and (b). Next, a drive circuit that controls the excitation current to the coil 24 according to the output of the magnetically sensitive element 32 will be described. As shown in FIG. 5, one end of the three-phase coils 24a to 24c is
It is assumed that they are commonly connected to form a star connection. The other end of each of the coils 24a to 24C is connected to a connection point of a series circuit in which two switching elements Q, to Q6, each consisting of a transistor or a MOSFET, are connected in series.
Further, both ends of each series circuit are connected to both ends of a DC power supply E. The conduction timing of each switching element Q, -QG is controlled by a timing circuit shown in FIG. That is, the conduction timing of each switching element Q, ~Q, is
The output of the magnetically sensitive element 32 is controlled based on the output of the magnetically sensitive element 32 (see FIG. 7(a)),
The signal is input to a position detection comparator 51, which is a position detection section, and an origin detection comparator 52, which is an origin detection section. The position detection comparator 51 is a magnetically sensitive element 32
is set to detect the zero crossing point of the output of (7th
(See Figure (b)), and the origin detection comparator 52 is set so that an output is obtained when the output level of the magnetically sensitive element 32 is equal to or higher than a predetermined level. This level is adjusted by a variable resistor VR for setting a reference value. The output of the position detection comparator 51 is output from the selector switch 53.
The signal is input to the hexadecimal counter 54 via the hexadecimal counter 54 and converted into a 3-bit address signal (see FIGS. 7(c) to 7(e)). This address signal is an address signal to the ROM 55, and the control data written in the corresponding address in the ROM 55 is read out, and the above-mentioned switching elements Q, to Q6 are controlled in accordance with this control data. (See Figure 7(f) to (k>). In other words, the ROM
The energization pattern for each of the coils 24a to 24c is written in 55 as control data, and the energization pattern is read out in accordance with the above-mentioned address signal to control each switching element Q, to Q6. By the way, with only the above configuration, the absolute position of the rotor 1 is unknown.
It is unclear whether 4a to 24c should be excited. Therefore, at startup, the changeover switch 53 is switched so that the output of the oscillator 56 is input to the hexadecimal counter 54. At this stage, the addresses in the ROM 55 are sequentially incremented, and even if the rotor 1 is initially unable to rotate, it will eventually reach a current pattern that allows the rotor I to rotate. When the rotor 1 begins to rotate in this manner, an output is provided to the origin detection comparator 52. That is, when the rotor 1 starts rotating, . 8th
As shown in FIG. The comparator 52 is shown in FIG.
) Outputs the origin detection signal as shown in (). Since this position becomes the rotation origin of the rotor 1, the origin detection signal is input to the flip-flop 57 (R-S flip-flop).
As shown in FIG. 8(c), the selector switch 53 is switched as the output of the clip-flop 57 rises. That is, the hexadecimal force counter 54 is separated from the oscillator 56 and connected to the position detection comparator 51, and thereafter operates as described above to continue rotation.

[Embodiment 2] In this embodiment, as shown in FIG.
Only one of the magnetic poles is strongly magnetized. Although the yoke 35 is not provided in this structure, when the magnetic sensing element 32 faces a strongly magnetized magnetic pole, a larger output can be obtained than other magnetic poles, so it works in the same way as when the yoke 35 is provided. It is.

Embodiment 3 In this embodiment, as shown in FIG. 10, only one of the magnetic poles of the position detection magnet 31 is made to protrude more than the other magnetic poles. Therefore, when this magnetic pole faces the magnetically sensitive element 32, the magnetically sensitive element 32
As a result, as in the case where the yoke 35 is provided, a larger output can be obtained from the magnetically sensitive element 32 than the other magnetic poles. Furthermore, in each of the above embodiments, the magnetically sensitive element 32 was placed opposite the circumferential surface of the position detecting magnet 31, but as shown in FIG. may be made to face each other. In this case, the position detection magnet 31 is magnetized in the thickness direction so that the magnetic pole that determines the origin position protrudes in the thickness direction.

【Effect of the invention】

As described above, the present invention includes one magnetically sensitive element, and the drive circuit includes an origin detection section that detects the rotation origin of the rotor based on the output of the magnetically sensitive element, and a drive circuit that detects the rotation origin of the rotor based on the output of the magnetically sensitive element. A position detector is provided to detect the rotational position of the rotor from the origin, and the excitation current applied to each phase of the electromagnet is controlled based on the rotational origin and the rotational position, so the position of the magnetic sensing element can be controlled. Even if there is a variation in the timing of the excitation current flowing through each phase of the electromagnet, there is no variation in the timing of the excitation current, which has the advantage of stabilizing the operating characteristics of the product. In addition, because there is only one magnetically sensitive element, compared to conventional structures that have multiple magnetically sensitive elements, variations in the characteristics of each magnetically sensitive element do not become a problem, improving reliability. It is. Furthermore, since there is only one magnetic sensing element, the speed signal depends only on the magnetized position of the position detection magnet, so speed signals with accurate intervals can be obtained. Moreover, it has the advantage of reducing the number of parts and manufacturing costs. The position detection magnet is magnetized to have a number of magnetic poles equal to the product of the number of magnetic poles of the rotating magnet and the number of phases of the electromagnet, and is configured so that the output of the magnetic sensing element for one magnetic pole is distinguished from the output for other magnetic poles. If the rotation origin is determined based on the output of the magnetically sensitive element at the position facing the one magnetic pole, the origin position can be easily detected. In order to distinguish one magnetic pole of the position detection magnet from the other magnetic poles, the other end of the yoke, one end of which is opposite to the one magnetic pole, is coupled to the position detection magnet, and the one magnetic pole is connected to one surface of the magnetic sensing element. If the one end of the yoke is made to face the other surface of the magnetically sensitive element at opposing positions, the magnetically sensitive element will pass through the magnetically sensitive element more at the position where the magnetically sensitive element exists between the one magnetic pole and the yoke than at other positions. Since the amount of magnetic flux increases, a different output can be obtained than when the magnetically sensitive element faces another magnetic pole. Furthermore, even if the position detection magnet is magnetized so that the one magnetic pole has a higher magnetic flux density than the other magnetic pole, the position where the one magnetic pole faces the magnetic sensing element is different from the position where it faces the other magnetic pole. will give different outputs. . Alternatively, the position detection magnet is formed in such a shape that the distance from the magnetically sensitive element at the position where the one magnetic pole faces the magnetically sensitive element is smaller than the distance from the magnetically sensitive element at the position where the one magnetic pole faces the other magnetically sensitive element. Even in this case, when one magnetic pole and the magnetic sensing element face each other, a different output can be obtained than when they face the other magnetic pole.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing Embodiment 1 of the present invention, FIG. 2 is a perspective view of a position detection magnet used in the above, and FIG. 3 shows the positional relationship between the position detection magnet and the magnetically sensitive element used in the above. 4(n) and 4(b) are respectively perspective views showing other examples of the position detection magnet, FIG. 5 is a circuit diagram showing a part of the drive circuit used in the above, and FIG. 6 is the same as the above. Block diagrams of the part that controls the timing of the drive circuit used, FIGS. 7 and 8
1 is an explanatory diagram of the same operation as above, FIG. 9 is an explanatory diagram showing an example of magnetization of the position detection magnet used in Embodiment 2 of the present invention, and FIG. 10 (
a) (b) and FIG. 11 (aHb) are perspective views showing a position detection magnet used in Example 3 of the present invention, and FIG. 11 (aHb), respectively.
FIG. 2 is a sectional view showing a conventional example, and FIG. 13 is an explanatory diagram of the same operation. 1... Rotor, 2... Stator, 11... Rotating shaft,
DESCRIPTION OF SYMBOLS 13... Rotating magnet, 21... Electromagnet, 31... Magnet for position detection, 32... Magnetic sensing element, 35... Yoke, 51... Combare plate for position detection, 52...
Comparator for origin detection. 1...Rotor

Claims (5)

[Claims] (1) A fixing device consisting of a rotor in which rotating magnets that are alternately magnetized with different polarities in the rotational direction are fixed to a rotating shaft, and multi-phase electromagnets that are arranged to face the magnetic poles of the rotating magnets and form a rotating magnetic field. a position detection magnet which is separate from the rotating magnet and which is fixed to the rotating shaft and magnetized with different polarities alternately in the direction of rotation; The drive circuit includes one magnetically sensitive element installed in the magnetically sensitive element, and a drive circuit that controls excitation current flowing through the electromagnets of each phase based on the output of the magnetically sensitive element. an origin detection unit that detects the rotation origin of the rotor;
and a position detection unit that detects the rotational position of the rotor from the rotational origin based on the output of the magnetically sensitive element, and controls the excitation current flowing through each phase of the electromagnet based on the rotational origin and the rotational position. Features a brushless motor. (2) The position detection magnet is magnetized to a number of magnetic poles equal to the product of the number of magnetic poles of the rotating magnet and the number of phases of the electromagnet, and the output of the magnetic sensing element for one magnetic pole is distinguished from the output for other magnetic poles. 2. The brushless motor according to claim 1, wherein the rotation origin is determined based on an output of a magnetically sensitive element at a position facing the one magnetic pole. (3) The other end of a yoke whose one end faces the one magnetic pole is coupled to the position detection magnet, and the one end of the yoke is magnetically sensitive at a position where the one magnetic pole faces one surface of the magnetically sensitive element. 3. The brushless motor according to claim 2, wherein the brushless motor faces the other surface of the element. (4) The brushless motor according to claim 2, wherein the position detection magnet is magnetized so that the one magnetic pole has a larger magnetic flux density than the other magnetic pole. (5) The position detection magnet is formed in a shape such that the distance from the magnetically sensitive element at the position where the one magnetic pole faces the magnetically sensitive element is smaller than the distance from the magnetically sensitive element at the position where the above magnetic pole faces the other magnetically sensitive element. The brushless motor according to claim 2, comprising: