JPS63262088A - Brushless motor - Google Patents

Abstract

PURPOSE:To reduce a noise by counting by a counter the output pulse of a frequency generator, generating a current pattern preset in response thereto, and feeding a driving current. CONSTITUTION:A flat brushless motor is composed of a rotor 2 secured to a rotary shaft 1, a stator 3, an FG magnet 11a for forming a frequency generator 11, and a detector 11b. This driving circuit is composed of a rotating direction detector 19, an incremental/decremental counter 12, an ROM 13, a D/A converter 20, current pattern signal changeover switches 14-16, a rotating speed control voltage control variable gain amplifier 21 and a driving amplifier 22, etc. Thus, the rotor 2 is rotated, a count signal is supplied from the generator 11 to the counter 12, data are sequentially read out from the ROM 13 by the counted value, and driving currents are supplied to the stator coils 3a-3c.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a brushless motor suitable for use in, for example, a capstan motor of a video tape recorder.

[Summary of the invention]

The present invention provides a brushless motor suitable for use as a capstor/motor of a video tape recorder, for example, which includes a rotor provided with a plurality of magnets, a stator provided with a plurality of coils, and a frequency generator configured to generate a number of pulses and to be readable stationary; and an M to which the output signal of the frequency generator is supplied.
A base counter (here, M is a frequency scattering for one rotation of the rotor, a driving current pattern generating means that generates a current pattern to flow through the coil of the stator in accordance with the count value of this M base counter, and this M base). By providing a reset current supply means that supplies a predetermined reset current to this coil when a reset signal is supplied to the counter, the drive is applied to the stator coil without using a rotor rotational position detector such as a Hall element. The current can be controlled, the size can be reduced by not providing this rotational position detector, and since this rotational position detector is not provided, the installation of this rotational position detector can control the current switching timing to the stator coil regardless of position accuracy. Accuracy can be improved, torque ripple can be reduced, and noise can be reduced.

[Conventional technology]

Conventionally, a flat brushless motor as shown in FIG. 5A has been used as a capstor/motor for a video tape recorder. In this Fig. 5A, (1) is the rotation axis, (
2) is a rotor that rotates together with this rotating shaft (1), and (3)
is a stator arranged opposite to this rotor (2).

As shown in FIG. As shown in FIG.
3-phase stator coils (3a) arranged at 0 intervals,
It is composed of (3b) and (3C). Further, three Hall elements (4a), (4b), and (4C) for detecting rotational position are arranged on this stator t31 at intervals of 120 degrees in terms of phase or electrical angle. The circuit of the flat brushless motor shown in FIG. 5 is constructed as shown in FIG. That is, in FIG. 6, (5) indicates a DC power input terminal, and the DC voltage supplied to this DC power input terminal (5) is connected to Hall elements (4a), (4b), and (4) for detecting rotational position.
4C) respectively, and the Conohole elements (4a) and (
The rotational position detection signals of the rotor (2) obtained in 4b) and (4C) are transmitted to amplifier circuits (7a), (7b) and (4C), respectively.
7C) via stator coil y (3a), (3b
), (3C) to a bidirectional energization pattern signal forming circuit (8). In this bidirectional energization pattern signal forming circuit (8), as is well known, a Hall element (4a),
(4b) 6 types of energization pattern signals are formed from the rotational position detection signals from (4c), and these 6 types of energization pattern signals are respectively output to six output terminals (8a) (8b)...-
...Output to (8f). This output terminal (8a
X8b)...The stator coil (31X
3b) A predetermined driving undercurrent is supplied to (3c).

In this example, this bidirectional energization pattern signal forming circuit (
8) six output terminals (8a) (8b)...
8f) are connected to npn transistors (9a) (9b) and
......A variable battery u0 for rotational speed control is connected to each pace of (9f), and the voltage value of the collector of each transistor (9a), (9b), and (9C) can be varied. Connect to the positive electrode and ground the negative electrode of this variable battery αα, and connect the transistors (9aX9b) and (9C)
The respective emitters of transistors (9f) (9e)
and (9d), and connect the connection point of the emitter of the second class transistor (9a) and the collector of the transistor (9f) to one end of the stator coil (3a), and connect the emitter of the transistor (9b) and the collector of the transistor (9f) to one end of the stator coil (3a). Connect the connection point of the collector (9e) to the stator coil (3b)
The connection point of the emitter of the transistor (9c) and the collector of the transistor (9d) is connected to the lower end of the stator coil (3c), and the second stator coil (3
a) The other ends of (3b) and (3C) are connected to each other, and the emitters of transistors (9f), (9e) and (9d) are grounded, respectively. In the conventional example shown in FIG. 6, the bidirectional energization pattern signal forming circuit (8 ) of 6
A predetermined energization pattern signal is obtained from the two output terminals (8a), (8b), ... (8f), and a drive current is supplied to the stator coils (3a), (3b), and (3C) in accordance with this. , the rotor (2) can be rotated at a predetermined speed according to the voltage value from the variable battery Uα.

[Problem that the invention seeks to solve]

Recently, the brushless motors used as capstan motors in such video tape recorders have become smaller and thinner in both the radial and thickness directions, and rotational position detectors such as Hall elements are also becoming smaller and smaller. be. However, stator coil (3a) for downsizing
(3b) If a printed coil is used as (3c), there is a problem with the location of the rotational position detector such as a Hall element. Therefore, the error in the detected angle becomes large, and the switching timing of the drive currents of the stator coils (3a, 3b, and 3c) is shifted, resulting in an inconvenience that torque ripple worsens.

In view of these points, it is an object of the present invention to make it possible to further reduce the size of the brushless morph, improve the accuracy of the timing of switching current to the stator coil, and reduce torque ripple. shall be.

[Means for solving problems]

The brushless motor of the present invention has a rotor equipped with a plurality of magnets, for example, eight poles, as shown in FIGS. 1 and 2, for example.
2), and multiple, for example, 3-phase coils (3a) (3b) (3
c), a frequency generator αυ that generates a number of pulses corresponding to the number of rotations of the rotor (2), and is configured to be readable stationary, and an output signal of the frequency generator αυ. The supplied M-ary counter (here, M is the number of pulses generated by the frequency generator (lυ) for one revolution of the rotor (2), Fp, for example, 4801, and the number of magnet poles of this rotor (2), P, for example. ) az and
The coil (
Drive current pattern generation means (13aX13b) (13c) that generates a current pattern to flow in
), and a reset current supply means (141a) that supplies a predetermined reset current to the coils (3a), (3b, and 3c) when a reset signal is supplied to this M-ary counter (lz).
9ueαD.

[Effect]

According to the present invention, the output pulses of the frequency generator αυ, which generates pulses corresponding to the rotational speed of the rotor (2), are counted by an M-ary counter, for example, a 120-adic counter (125), and the output pulses are predetermined in accordance with this count value. Since a set 'WLa pattern is generated and a drive current corresponding to this current pattern is passed through the stator coils (3a) (3b) (3c), the rotor (
2) The rotation can be controlled. Therefore, the size can be reduced by not providing this rotational position detector. Also, when a reset signal is supplied to the M-ary counter az, the stator coil (3a) (
3b) (3c) by supplying a predetermined reset current to the rotor (
Since the position 2) is the predetermined position and no rotational position detector such as a Hall element is provided, the rotational position detector can be installed on the stator coil (
The accuracy of the current switching timing to 3a) (3bX3C) can be improved, the torque ripple can be improved, and the noise can be reduced.

〔Example〕

Hereinafter, one embodiment of the brushless motor of the present invention will be described with reference to FIGS. 1, 2, and 3.

In FIGS. 1 and 2, parts corresponding to those in FIGS. 5 and 6 are designated by the same reference numerals, and detailed explanation thereof will be omitted.

In this example as well, the present invention is applied to a flat brushless morph as shown in FIG.
The rotor (2) fixed to the rotor (2) is composed of a disk in which a plurality of magnets, for example eight poles, are arranged at regular intervals along the circumferential direction, as shown in FIG. As shown in FIG. 5C, for example, the stator (3) arranged at It is composed of three-phase stator coils (3a), (3b), and (3c) which are connected to each other and whose phases are arranged at intervals of 120 electrical degrees.

In this example, a ring-shaped FG magnet (
A detector (llb) consisting of a magnetoresistive element constituting a stationary readable frequency generator circle is provided opposite the FG magnet (lla).

In this example, the number Fp of pulses obtained on the output side of the detector (llb) when the rotor (2) makes one revolution is, for example, 480. In addition, in this example, the detector (ll
As b), two magnetoresistive elements are arranged with a phase difference of 90 degrees, and a sine wave signal and a CO
Two detection signals of the S-wave signal are obtained. The two detection signals obtained from this frequency generator Uυ are sin
The wave signal and the COS wave signal are supplied to the rotation direction detection circuit α■ via amplifier circuits (18a) and (18b), respectively.

In this rotational direction detection circuit, this tracking signal and c
The rotation direction of this rotor (2) is determined by the OA wave signal, and the up/down counter α2 is set to up count when the rotor (2) is rotating in the forward direction based on the output signal of this rotation direction detection circuit CI9. When 2) is reversed, the up/down counter α2 is set to count down. Further, in this example, the output signal of the frequency generator Uυ obtained at the output side of the amplifier circuit (18a) is supplied to the up/down counter 12 as a count signal. This up/down counter uz is the rotor (2
), the number of pulses obtained on the output side of the frequency generator αυ per rotation of F9 is, for example, 480, and this rotor (2)
When the number of magnetized poles of the magnet is P, for example 8 poles, the M-ary counter determined by, for example, 120-ary C/R.

This up/down counter (1z output signal is used as an analog signal in ROM (133X13b) and (13C)
supply to. This ROM (13a) (13b) and (
13C) stores the current patterns of the drive currents flowing through the stator coils (3a), (3b), and (3C) as digital signals.

For example, this ROM (13a) (13b) and (13c
), respectively, with 120 addresses from O to 119, and
As shown in Figures E and F, one period of the decoy wave signal having a phase difference of 120 is divided into 120 equal parts, and the divided signals are sequentially stored in corresponding addresses as digital signals. This R.O.
M(13a), (13b), and (13C) are designed to sequentially output data signals at addresses designated by the count value of the cono-up z-run counter (17J). The respective output signals are supplied to D-A converters (20a) (20b) and (20C) that convert digital signals into analog signals, and these L)-A converters (20a) (20b) and (20c) The t-flow pattern signals as shown in the third diagram, E and F, obtained at the respective output sides of the
5 and ILQ, one fixed contact (14s) (15
s) and (16s), and this changeover switch u4)
The movable contacts (14a), (15a), and (16a) of as and four are respectively connected to voltage-controlled variable gain amplifier circuits (21a), (21b), and (21C) for rotational speed control, and drive amplifier circuits (22a) ( stator coils (3a) (3b) and (3C) through a series circuit with (22b) and (22c).
), and this stator coil, /I/(
3a) Connect the other ends of (3b) and (3C) to each other.

In FIG. 1, the symbol indicates a speed control signal input terminal to which a speed control signal for rotational speed control is supplied, and the variable gain amplifier circuit ( 21a), the gain of each of (21b) and (21c) is controlled.

In addition, in this example, when the up/down counter z is reset, the stator coil /' (3aX3b) and (
3C) to bring the rotor (2) and stator coils (3a), (3b), and (3C) into a predetermined positional relationship. In other words, in this example, the OS is connected to the 9111 fixed contact (14R).
Pressure is supplied to the reset side fixed contact of changeover switch u9 (
15R) is supplied with a predetermined positive voltage Vo, and a predetermined negative voltage - is supplied to the reset side fixed contact (16R) of the changeover switch 4.
By supplying Vo and resetting the up/down counter circle from the reset signal generation circuit α,
The period during which this reset signal exists This changeover switch Iα
The movable contacts (14g) (15a) and (16a) of 9 and u are connected to this reset side fixed contact (14R) (15
R) and (16FL). At this time, the magnet of the rotor (2) and the stator coil (3a) (
3b) The relationship with (3C) is as shown in Figure 3, that is, the boundary line (2a) between the S and N poles of the rotor (2) is the midpoint between the stator coils (3b) and (3C). It is a positional relationship.

In this case, as shown in FIG. 3B and C, if this positional relationship is deviated, the rotor (2) rotates in the direction shown by the arrow, and the rotor (2) and stator coils (3a) (3b)
The positional relationship with (3c) is as shown in Figure 3.

This changeover switch (141 us and the four movable contacts (14a), (15a), and (16a) are connected to one fixed contact (x48) (xss) except when this reset signal is received.
) and (168), respectively.

Further, the reset signal generation circuit y6 is configured to generate a reset signal when the power is turned on or when an instruction is received from outside, such as from a system control device of the set. Further, in this example, when the rotor (2) is reversed, the stator coils (3a) and (3b) are flowed in three directions (the flow pattern is reversed in positive and negative directions).

Since this example is configured as described above, when the power is turned on, a reset signal (17a) as shown in FIG. 3G is sent from the reset signal generation circuit (Lz) to the up/down counter (IZK%
The up/down counter α is reset and the movable contacts (14a), (15a) and (16a) of the changeover switch α (15 and αe) are set to the reset side fixed contacts (14R), (15R) and (16R). ), and at this time, a predetermined current io as shown in FIG.
) magnets and stator coils (3a) (3b) (3
The positional relationship with C) is set to a predetermined relationship as shown in FIG. 3A. When this reset signal (17a) is no longer present, the output of the up/down counter (12) becomes black and the ROM (
13a) (13b) and (13c) are respectively designated with address "0" and ROM (13a) (13b) and (13C)
(7) The respective address "0" outputs are output, and corresponding drive currents as shown in the third diagram, E and F, are supplied to the stator coils (3a), (3b) and (3C), This causes the rotor (2) to rotate, and according to the rotation of the rotor (2), a count signal is supplied from the frequency generator to the up/down/counter (Lz), which is then sent to the ROM (13a) according to the count of the counter 0z.
(13b) and (13c) "1" address, "2"address,
・・・・・・"Specify address 11'lJ, read the data 1st time, and read this stator coil /l/(3a)(
3b) and (3C), respectively, and supply drive currents as shown in E and F, and repeat this sequentially to drive the rotor (2).
) as variable gain amplifier circuits (21a) (21b) and (21
c) Rotates at a predetermined speed determined by the gain. In this case, since this example uses a frequency generator συ that can continue without interruption, a count signal can be obtained even when the rotation speed of the rotor (2) is slow. The ROM (13a
The data of X13b) and (13c) can be read out satisfactorily.

As described above, according to this example, the count signal obtained according to the rotation of the rotor (2) from the frequency generator Uυ provided in relation to the rotor (2) is counted by the 120-decimal up/down counter α2, and The data of the current pattern set in advance corresponding to the count value is stored in the ROM (13a).
(13b) (13c) The drive current corresponding to this current pattern is generated by the stator coil" (3a) (31))
and (3c), the rotation of the rotor (2) can be controlled without using a rotational position detector such as a Hall element. Therefore, according to this example, the size can be reduced by not providing this rotational position detector. Also, when a reset signal is supplied to this 120-decimal up/down counter α2,
A predetermined reset current is supplied to the stator coil/' (3a) (3bX3c) to set the position of the rotor (2) to a predetermined position, and since a rotational position detector such as a Hall element is not provided, it is necessary to install this rotational position detector. Regardless of the position, size, etc., the stator coils (3a) (3b) and (
The accuracy of the current switching timing to 3C) can be improved, the torque ripple can be improved, and the noise can be reduced.

FIG. 4 shows another embodiment of the invention. In the example shown in FIG. 4, even when a counting error of the counter q7J occurs due to bearing loss or the like in the example shown in FIG. 1, it can be corrected accurately. In the example in FIG. 4, the up-down cow/re (pre-seven at 1z) [[l is provided, and this preset circuit c! A predetermined number of 41, for example "29", is preset at ℃, and this up/down counter α2
When a load signal is supplied to the load terminal of the up/down counter u20, the count value of the up/down counter u20 is set to the preset value, for example, "29". In this example, both ends of the stator coil (31) are connected to the detection terminals of the zero-cross point detection circuit (to), and the zero-cross point detection circuit G detects whether the current flowing through the stator coil (3a) is negative or negative. The configuration is such that a pulse of a high level "'1" is outputted as shown in FIG. The output signal of this zero-cross point detection circuit (c) is supplied to one input terminal of the AND circuit (to). Also, the amplification port%
(isb) is supplied to the rotation detection circuit @, and in this rotation detection circuit (2), when the rotation speed of the rotor (2) reaches a predetermined speed, that is, a speed at which the zero cross point can be detected. It is designed to output a high level "1" to the output side. The output signal of this rotation detection circuit (3) is supplied to the other input terminal of the AND circuit, and the output signal of this AND circuit (to) is connected to the load signal coil (3a) at the load terminal of the up counter (13). A load signal as shown in Fig. 3H is obtained at the time when the drive current shown in Fig. 3 changes from negative to positive, and this load signal is supplied to the load terminal of the up/down counter Z, and this Since this count value is preset to a preset value, for example "29", at the time of the load signal, the count value of the adapter "run counter α2" and R
Since the current pattern data from OM (13a), (13b), and (13c) match correctly, it is possible to always eliminate erroneous counting of the up-counter (12). The same effects as in FIG. 1 can be obtained.

In the above embodiment, the stator coils (3a) (3b
) (3c), the current pattern supplied is a sine wave, but instead it may be a step wave as shown by broken lines in E and F in Figure 3, or a waveform of other values may be used. Further, in the above embodiment, a changeover switch (141u51ue) was provided as a reset current supply means to switch and supply a predetermined voltage at the time of reset, but instead of this, a ROM (13
a) Of course, a specific address may be provided for each of (13b) and (13c), data corresponding to the reset current may be stored in advance, and this specific address may be designated by the reset signal. be. Further, the present invention is not limited to the above-described embodiments, and it goes without saying that various other configurations can be adopted without departing from the gist of the present invention.

〔Effect of the invention〕

According to the present invention, the stator coil (3a
) (3c), the structure can be reduced to the extent that this rotational position detector is not provided, and since this rotational position detector is not provided, the installation of this rotational position detector can improve positional accuracy, Stator coils regardless of size (
The accuracy of the current switching timing to 3a), 3b, and 3c is improved, and the torque ripple can be improved and noise can be reduced.

[Brief explanation of drawings]

FIG. 1 is a circuit configuration diagram showing an embodiment of the brushless motor of the present invention, FIG. 2 is a sectional view of an embodiment of the brushless motor of the present invention, FIG. 3 is a line diagram for explaining the present invention, and FIG. 4 5 is a circuit diagram showing another embodiment of the present invention, FIG. 5 is a diagram showing an example of a conventional brushless motor, and FIG. 6 is a circuit diagram showing an example of a conventional brushless motor. (2) is the rotor, (3) is the stator, (3a) (3b)
and (3C) are respectively stator coils, αυ is a stationary readable frequency generator, (1z is an up-counter, (13a), (13b) and (13C))
OM, (14) C10 and ue are changeover switches, (1
7) is a reset signal generation circuit. Figure 3

Claims (1)

[Claims] A rotor provided with a plurality of magnets, a stator provided with a plurality of coils, a frequency generator configured to generate a number of pulses corresponding to the number of rotations of the rotor and to be readable stationary; M to which the output signal is supplied
(where M is the number of pulses generated by the frequency generator per one revolution of the rotor is F_p, and the number of magnet poles of this rotor is P, then M = 2F_p/P.) drive current pattern generating means for generating a current pattern to flow through the coil in accordance with the count value of the M-ary counter; and a reset current that supplies a predetermined reset current to the coil when a reset signal is supplied to the M-ary counter. A brushless motor characterized by being provided with a supply means.