JPH0458779A - Controller and control method for dc brushless motor - Google Patents

Abstract

PURPOSE:To stop a rotor quickly and accurately by employing a first reference signal to be compared with the rotational signal of a rotor and a second reference signal having lower frequency, comparing a sufficiently low rotational speed with the second reference signal, and applying brake for a predetermined time upon droppage of the rotational speed of rotor to that level. CONSTITUTION:A monitor means 2 produces an FG signal representing the rotational speed of rotor. The FG signal is fed to a brake circuit 7 and a switching element 3 selectively connects a plurality of reference signal sources including a first reference signal source 4, a second reference signal source 5 and a third reference signal source, as required. The third reference signal source 6 produces a reference signal having lower frequency F3. The comparing/ braking circuit 7 compares the FG signal with the reference signal and a control power supply 8 feeds a current for stopping a motor l based on the difference. When the frequency of the reference signal is decreased as brake operation proceeds, accuracy in the brake operation is improved and the motor l is stopped accurately.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to brushless DC motors, and more particularly to braking of brushless DC motors.

[Prior Art] In hard disk drives, optical disk drives, and the like, it is desirable to rapidly accelerate and decelerate disks. When decelerating the disk, it is desirable to brake the motor that drives the disk.

FIG. 3 shows a conventional motor braking circuit.

A controlled current is supplied to the stator coil 11 from the motor drive ICl3. Each stator coil 11 is connected to a snubber circuit 14 for absorbing noise. A rotor arranged around the stator coil has permanent magnets. By rotating the rotor driven by the stator coil 11, a vibrating magnetic field is generated around it. This magnetic field causes the Hall element 15 to generate a Hall voltage, causing a voltage to be accumulated across the capacitor 16. This voltage is supplied to the motor drive ICl3 and forms a rotor rotation monitoring signal. The current supplied to stator coil 11 is controlled based on this monitor signal. Note that the signal from at least one Hall element is supplied to an amplifier illustrated as an operational amplifier 17 in the figure, and forms an FG flaw signal representing the rotation rate of the rotor. This FG flaw signal is supplied to the motor brake IC 23 via the capacitor C7.

The 5PON terminal that instructs braking/driving is supplied with an O level signal during driving and a level signal during braking. This 5PON
The signal is supplied to the reverse torque generation instruction terminal 18 of the motor drive ICl3 via the integrating circuit 26 and the OR circuit 28. The motor brake 4I C has an oscillation circuit F! including a crystal oscillator 21. @22 is connected, and this oscillation signal is frequency-divided by a frequency divider circuit 24 to form a lower frequency reference signal. The reference signal and the FG flaw signal supplied via the capacitor C7 are compared by a comparator circuit 25, and a brake control signal is generated based on the difference. This braking control signal is transmitted to the motor drive ICl via an integrating circuit 27.
It is supplied to the control terminal 19 of No. 3 to execute braking according to the rotation sequence. The output terminal of the OR circuit 1I128 is connected to the output side of the comparison circuit 25 by a diode D1.

With this configuration, when the 5PON signal becomes high level and braking is instructed, the braking instruction is given to the motor drive ICl3. While the rotation of the rotor is high, a braking control signal is sent from the comparison circuit 25 to the terminal 19 of the motor drive ICl3, and a sufficient amount of braking is applied. When the rotation of the rotor gradually decreases and reaches a predetermined value (for example, 1/8 of the constant rotation speed), the output of the comparison circuit 25 changes,
The output signal of the control circuit 29 is inverted to a low level. This low level is the terminal 18 of the motor drive ICl3.
When supplied to , braking operation stops.

However, since the integrating circuit 26 is connected to the OR circuit 28, a change in the output of the control circuit 29 is transmitted to the motor drive ICl3 after a certain period of time has elapsed. During this time, the final braking takes place.

That is, when the rotor is braked and decelerated and reaches a predetermined rotation speed, a brake release signal is generated from the motor brake 41023, and this brake release signal is transmitted to the motor drive ICl3 after a predetermined period of time has elapsed. Within this predetermined time, the rotor is further braked and becomes in a state where the rotational speed is approximately O. Note that a signal is formed at the 5PFG terminal via the FG flaw signal transistor Tri.

[Problems to be Solved by the Invention] According to the conventional technology described above, the rotation of the rotor is monitored, and when the rotation of the rotor decreases to a predetermined rotation rate according to the rotor braking signal, a brake release signal is generated. Braking is released after a predetermined period of time has elapsed. However, when the constant speed rotation rate of the rotor is high, when the inertia of the rotor changes, etc., it is not easy to stop the rotation of the rotor in a short time and accurately by such control.

An object of the present invention is to provide a braking method and a braking device for a brushless DC motor that can accurately stop the rotation of a rotor in a short time.

[Means for Solving the Problems] A method for braking a brushless DC motor of the present invention is a method for braking the rotation of a rotor of a brushless DC motor, comprising:
a step of comparing a signal representing the rotation of the rotor with a first reference signal and supplying a control signal for controlling the flow of a current in the stator coil to generate a force in a direction to reverse the rotor; When the voltage falls below a predetermined value, the signal representing the rotation of the rotor is compared with a second reference signal having a lower frequency than the first reference signal, and a current is applied to the stator coil to generate a force in the direction of rotating the rotor in reverse direction. and supplying a control signal to control the method.

[Function] Since the first reference signal and the second reference signal having a lower frequency are used as the signals to be compared with the signal representing the rotation of the rotor, it is possible to always know the rotation sequence of the rotor with high precision. I can do it.

Therefore, by setting a sufficiently low rotational speed as the reference rotational speed and applying braking for the remaining predetermined time when the rotor rotational speed drops to this value, the motor rotor can be moved accurately and quickly. It is possible to stop it.

[Embodiment] FIG. 1 schematically shows a braking device for a brushless DC motor according to an embodiment of the present invention.

In the figure, a motor 1 includes a rotor having a permanent magnet and a stator having a coil. A current is supplied to the stator coil from a control current source 8 to rotate the rotor. The rotation of the rotor is monitored by the monitor means 2, and an FG flaw signal representing the degree of rotation is generated. This FG flaw signal is supplied to the comparison/braking circuit 7, and also controls the connection of the switch element 3. A plurality of reference signal sources such as a first reference signal source 4, a second reference signal source 5, and (if necessary, a third reference signal source 6, etc.) are connected to the switch element 3, and one of them is selectively connected to the switch element 3. connected to. A first reference signal source 4 generates a reference signal of frequency F1.

Similarly, the second reference signal source 5 and the third reference signal source 6 generate reference signals at second and third frequencies F2 and F3, which are lower frequencies. By connecting the movable contact of the switch element 3 to one of these reference signal sources, the frequencies F1,
Either signal F2 or F3 is supplied to the comparison/braking circuit 7. The comparison/braking circuit 7 compares the frequencies of the FG flaw signal and the reference signal, and supplies a braking signal based on the difference to the control current source 8. A current for stopping the rotor of the motor 1 is supplied from a control current source 8 . By reducing the frequency of the reference signal as the braking progresses, the accuracy of the braking is improved and the rotation of the rotor of the motor 1 is accurately stopped.

The braking operation of such a brushless DC motor will be explained with reference to FIG. 2.

First, when the braking mode starts, the rotational speed of the rotor is monitored in step S1, and the rotational speed is set as FG.Next, in step S2, the monitored rotational speed PG is lower than the predetermined rotational speed No. It is determined whether or not it is large. If the rotation rate of the rotor is higher, follow the YES arrow and move to step S3, where the first FG flaw signal
The difference from the reference signal F1 of the reference signal source is stored as ΔF (step 53). Next, a control signal is generated based on this frequency difference ΔF (step S4), and braking is performed based on the control signal. (Step S5), for example, a braked current is supplied to the stator coil. As the rotation rate of the rotor decreases in accordance with the braking operation, the determination in step S2 eventually changes to No. When it is equal to or smaller than the FG flaw signal NO, the process moves to step S6 according to the No arrow, and it is determined whether the FG flaw signal is larger than the second reference rotation sequence N1. When FG is larger than N1, the process moves to step S7 according to the YES arrow, and a control signal is generated based on this frequency difference ΔF, in which the difference from the FG false signal F2 signal is stored as ΔF (step S8). , This control signal acts as a brake, and the rotation of the rotor further decreases (step S9).

Eventually, when the rotation of the rotor decreases and FG becomes equal to N1 or even smaller, step S10 is executed according to the NO arrow in step S6. That is, the time for braking thereafter is set by the timer. The motor is further braked for this set time (step 311).
, thus bringing the rotor to a halt.

Although the case in which two reference signals are used has been described in FIG. 2, the number of reference signal sources can be arbitrarily selected.

FIG. 4 is a circuit diagram showing a braking device for a brushless DC motor according to a specific embodiment of the present invention.

In the figure, stator coil 1 of a brushless DC motor
1 has a motor drive IC via a snubber 11114.
A Hall element 15 of 0, t to which a controlled current is supplied from l3 is provided near the rotor of the motor and monitors the rotation of the rotor. The output voltage of the Hall element 15 is supplied to the motor drive ICl3 via capacitors C1l, C12, and C13 to form a rotor rotation monitoring signal.

A signal from one Hall element (N3 in the figure) is used to form an FG signal representing the degree of rotation of the rotor. This FG false signal is supplied to the motor brake IC 23 via the capacitor C7.

In this embodiment, the motor drive IC is available as model number HA13403MP, and the motor brake IC is as model number TC9203F.
Use what you can get. When the high level of the 5PON signal indicating motor stop occurs, the braking instruction terminal 31 of the motor brake 1 (I023) becomes high level, and the high level signal is supplied to the reverse torque generation instruction terminal 18 of the motor drive ICI 3.FG The reference signal to be compared with the false signal is switched to 2 stages, and a reverse torque is generated until the rotation rate of the motor becomes 1/16 of the constant speed rotation rate.The motor brake IC 23 itself drops to 1/8 of the FG false signal. This type of brake is then released. Conventionally, this brake release was delayed by an integrating circuit, and the remaining braking was performed during that time.

In this embodiment, such a delay is not used, and the braking is released when the rotation rate of the motor decreases to 1/16.

An oscillation circuit 22 including a crystal oscillator 21 supplies an oscillation output to a frequency division circuit 24 of a motor brake IC 23. A zero frequency division circuit 24 supplies a reference signal formed by frequency division to a terminal 32.

The reference signal at terminal 32 is fed directly on the one hand and via flip-flop 1FF2 on the other hand to multiplexer MX. The frequency of the reference signal passed through flip-flop FF2 is reduced to 1/2.

Multiplexer MX selects one of these two reference signals and supplies it to comparison circuit 25.

Here, care must be taken because if the difference from the FG false signal reference signal is too large, the motor breaker 4IC will be reset. For this reason, the reference signal switching system #1 surrounded by the broken line
It has a configuration similar to i1135. The Fa signal is supplied to the negative terminal of the operational amplifier 10P1 via the transistor Tri. The operational amplifier OPI forms an inverted output signal and connects it to the capacitor C through resistors R6 and R7.
Charge 6. The terminal voltage of this capacitor C6 is supplied to the positive terminal of another operational amplifier OP2.6. operational amplifier OP
The output signal of No. 2 is supplied to the D terminal of flip-flop FFI. The CP terminal of the flip-flop FFI is connected to the 5PFG formed at the collector terminal of the transistor Tri.
A signal is applied.

As the FG false signal frequency decreases, the period of the 5PFG signal becomes longer. Then, the charge stored in capacitor C6 increases, and the terminal voltage of capacitor C6 increases. By detecting this change, the rotation sequence is detected, a control signal is generated from the Q terminal of the flip-flop 1FFI, and the reference signal selected by the multiplexer MX is switched to the one obtained from the Q terminal of the flip-flop FF2.

Comparison circuit 25 is connected to FG supplied via capacitor C7.
The reference signal supplied from the flaw signal multiplexer MX is compared.

That is, a signal representing the rotation rate of the rotor formed from the FG flaw signal is compared with a reference signal F1 or a reference signal F2 having a frequency of 1/2 of the reference signal F1 depending on its magnitude, and the signal is controlled based on the difference. Terminals 38 and 39 are supplied. From this control terminal 38,39 a control signal is supplied to the terminal 19 of the motor drive ICl3. That is, the third
In the circuit shown in the figure, there is only one type of reference signal to be compared, and the braking is controlled based on time after reaching a predetermined rotation sequence, but in this embodiment, the rotor rotation sequence is the first rotation sequence. When the frequency drops to 0, the reference signal is switched from a high frequency to a low frequency, and braking is effective until the second rotation sequence is reached.Since braking is controlled based on the 0 rotation sequence, it is not affected by inertia changes etc. First, the accuracy of motor braking is improved.

Note that the reference signal may be switched, for example, at the rated rotation speed 1.
The parameters of the reference signal switching control circuit 35 are selected so as to be carried out when the rotation rate decreases to /4.

The number of reference frequencies may be three or more as shown in Figure 1 instead of two, and the frequency of the second reference signal may be the same as the frequency of the first.
Not limited to 1/2 of the frequency of the reference signal, for example, 1/2
It may be 4 or 1/6.

The selection can be made depending on the type and nature of the motor to be braked.
Further, the timer control shown in FIG. 3 may be further combined.

Although the present invention has been described above in accordance with the examples, the present invention is not limited to these examples. For example, various modifications,
It will be obvious to those skilled in the art that improvements, combinations, etc. are possible.

[Effects of the Invention] As explained above, according to the present invention, by using reference signals of a plurality of frequencies, braking can be executed quickly and while monitoring the rotational speed of the motor over a wider range. A brushless DC motor can be stopped with high precision.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram showing a braking device for a brushless DC motor according to an embodiment of the present invention. FIG. 2 is a flowchart for explaining a braking method for a brushless DC motor according to an embodiment of the present invention. FIG. 4 is a circuit diagram showing a braking device for a brushless DC motor according to an embodiment of the present invention. Motor Drive IC Motor Brake IC Reference Signal Switching Control Circuit Patent Applicant Nidec Corporation Representative Patent Attorney Keishibu Takahashi Brushless DC Motor Monitor Element Switch Element Reference Signal Source Comparison/Braking Circuit Control Current Source Figure 2

Claims (3)

[Claims] (1). A method for braking the rotation of a rotor of a brushless DC motor, the method comprising: comparing a signal representing the rotation of the rotor with a first reference signal, and applying a current to a stator coil to generate a force in a direction to reverse the rotor. a step of supplying a control signal to control, when the rotation speed of the rotor falls below a predetermined value, a signal representing the rotation of the rotor and a second reference signal having a lower frequency than the first reference signal;
A method for braking a brushless DC motor, the method comprising the steps of: comparing the current with a reference signal, and supplying a control signal for controlling a stator coil to flow a current that generates a force in a direction to reverse the rotor. (2). The brushless DC according to claim 1, wherein the second reference signal is obtained by frequency-dividing the first reference signal.
How to control a motor. (3). a rotor including a permanent magnet; a stator including a coil for generating a driving magnetic field; a detection means for detecting rotation of the rotor and generating a signal representing a rotational speed; and a first reference signal having a first frequency. a second reference signal source that generates a second reference signal having a second frequency lower than the first frequency; and a first reference signal source that generates a second reference signal having a second frequency lower than the first frequency; switch means for selectively selecting one of the second reference signals; and comparing an output signal of the switch means with a signal representing the rotational speed to generate a control signal for braking the rotation of the rotor. A braking device for a brushless DC motor, comprising: a control circuit for controlling a current supplied to a coil of a stator based on a control signal output from the control circuit.