JP3126372B2 - Motor control circuit - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to motor control, and more particularly to control of a motor having a strong acceleration / deceleration function such as a motor for a storage disk device.

[Prior art] In a hard disk drive device, an optical disk drive device, etc., a disk is rapidly accelerated with a constant speed rotation.
It is desirable to be able to perform rapid deceleration. At the time of deceleration, it is desirable not to mechanically brake the disk but to generate a reverse rotation torque on the rotor of the motor from the viewpoint of the life and reliability of the apparatus. Hereinafter, the case of a DC brushless motor will be described.

For example, when an instruction to stop disk rotation is issued, a reverse rotation torque is generated in the motor to decelerate the rotor. The rotation speed (or phase) of the motor is detected so that the rotor does not reverse due to the reverse rotation torque, and it is determined whether or not the rotation has decreased to a predetermined reference value. I do. To stop at the fixed position,
Further, measures such as flowing a current only to a predetermined coil may be taken.

Such motor braking is typically used for motor braking.
It is performed by an IC and is executed by a circuit of a different system from the motor drive IC that controls the rotation speed of the motor.

[Problems to be Solved by the Invention] As described above, according to the related art, the motor drive IC and the motor brake IC are used for controlling the rotation of the motor. However, they do not accelerate and decelerate at the same time,
These circuits were functionally wasteful.

An object of the present invention is to provide a motor control circuit capable of performing a motor deceleration control with a simple configuration.

Another object of the present invention is to provide a motor control circuit in which the motor drive circuit can be used for decelerating the motor.

[Means for Solving the Problems] A motor control circuit according to the present invention comprises: an FG signal source for detecting rotation of a rotor of a motor to derive an FG signal; a rotation reference clock signal; A reference clock signal source for generating a reference clock signal for deceleration having a higher frequency, a means for generating a rotation or deceleration instruction signal, and comparing the FG signal with the reference clock signal for rotation at the time of rotation instruction. , When the FG signal is lower than the predetermined frequency,
Generate an acceleration signal, when deceleration is instructed, compare the FG signal with the reference clock signal for deceleration, and when the FG signal is higher than a predetermined frequency, according to the difference between the FG signal and the reference clock signal for deceleration. A discrimination circuit for generating a deceleration signal composed of a pulse signal having a pulse length.

[Function] When the motor is rotating, the FG signal is compared with the reference clock signal for rotation. When the FG signal indicating the rotation of the rotor is lower than a predetermined frequency, the motor is accelerated. When the FG signal is higher than a predetermined frequency, the motor is controlled by sharing the circuit between the rotation and the deceleration by performing the deceleration.

By controlling the rotation of the rotor based on the magnitude of the difference between the FG signal representing the rotation of the rotor and a predetermined value based on the reference signal, efficient control according to the current rotation speed can be performed.

FIG. 1 shows a motor control circuit according to an embodiment of the present invention.

In the figure, a portion 10 indicated by a broken line is a circuit portion manufactured as an IC.

The coils 1, 2, and 3 apply a magnetic field to a permanent magnet (not shown) of the rotor to rotate the rotor. Coil 1, 2,
When the rotor is driven and rotated by 3, Hall elements 6, 7, 8 provided in the vicinity of the rotation orbit of the rotor detect an oscillating magnetic field formed by the rotating magnet of the rotor. The rotation signals detected by the Hall elements 6, 7, and 8 are accumulated in the capacitors C101, C102, and C103, respectively, are stabilized, and are applied to the Hall amplifiers 11, 12, and 13, respectively.
A phase and a w-phase detection signal are generated. Each of these detection signals is
The signals are supplied to the matrix circuit 14 and generate signals for controlling the currents of the u-phase, v-phase and w-phase coils 1, 2 and 3, and are supplied to output amplifiers 16, 17 and 18. Output amplifier 16, 17, 18
Generates currents to be supplied to the coils 1, 2, and 3, respectively. Note that diodes D1, D2, and D3 for absorbing spike voltages and the like are connected to the coils 1, 2, and 3, respectively. The output currents of the output amplifiers 16, 17, and 18 are monitored, and the monitored current is detected by the current limiter detection resistor R100.
Grounded. The voltage between the terminals of the resistor R100 is integrated by the capacitor C107, applied to the-input terminal of the control amplifier 20, and supplied to the current limiter reference voltage source 19.
Is compared with the reference voltage supplied by If the current flowing through the coils becomes too high, the control amplifier 20 generates an output and controls the matrix circuit 14 via the gate 23 to limit the current supply to each coil. The capacitors C105 and C108 and the resistor R103 connected to the pins P10 and P14 form a phase compensation circuit 41. The midpoint feedback circuit 40 connected to the pin P14 also performs phase compensation. High temperature and low voltage protection circuit 25
A high temperature or low voltage is detected, and a signal is supplied to the matrix circuit 14 via the gate 23 to limit a current in an abnormal situation. An automatic gain control circuit (AGC) 15 receives signals from the matrix circuit 14 and controls the gains of the Hall amplifiers 11, 12, and 13.

Whether the motor is rotating forward or reverse,
A direction signal for stopping the operation is applied. This direction signal is latched by the direction latch 26 and supplied to the matrix circuit 14, the gate circuit 23, the frequency divider 32, and the speed discriminator 33.

For example, when the motor is rotating forward, the FG signal indicating the rotation of the rotor is formed by detecting the output of the hall amplifier 11 with the zero cross detector 27. The zero cross detector 27 generates one pulse in one cycle,
The rotation signal is supplied to the frequency divider 28. In response to the frequency division ratio selection signal, the frequency divider 28 divides the input pulse as it is, or divides it by 1/2, or divides it by 1/4 and outputs it. The modified FG signal supplied from the frequency divider 28 is output to the speed discriminator 33
Supplied to On the other hand, the crystal oscillator 30, the capacitor C109,
The oscillating circuit 31 with an external C110 oscillates at a constant frequency,
The oscillation signal is supplied to the frequency divider 32. The frequency divider 32 performs frequency division with different frequency division ratios based on the direction signal supplied from the direction latch 26, and supplies a reference signal to the speed discriminator 33. In normal rotation,
The speed discriminator 33 compares the reference signal supplied from the frequency divider 32 with the FG signal supplied from the frequency divider 28,
When the FG signal is lower than the reference signal, an acceleration signal for instructing acceleration is output to the terminal P6. For example, a pulse signal having a pulse length corresponding to the difference between the FG signal and the reference signal is output to the output terminal P6. This acceleration signal is transmitted through the resistor R1.
The integration is performed by the integration circuit 36 including the resistor R2 and the capacitors C1 and C2, and the integrated value is applied to the negative input terminal of the integration amplifier 35 through the terminal P7. The internal reference voltage from the internal reference voltage source 38 is applied to the + input terminal of the integrating amplifier 35. In this way, the integration amplifier 35 generates an output signal corresponding to the rotation speed of the rotor, and applies the output signal to the negative input terminal of the buffer amplifier 39. The + input terminal of buffer amplifier 39 receives an internal reference voltage. The output of the buffer amplifier 39 is supplied to the matrix circuit 14 through the gate 23 via the control amplifier 20. In the matrix circuit 14, each of the coils 1, 2, 3 is controlled based on the parameters of the output of the Hall amplifier, the acceleration signal, and the like.
Determine the current to be supplied.

At the time of deceleration, an inverted signal is supplied to the direction signal input terminal P9. The inverted signal is supplied to a frequency divider 32 and a speed discriminator via a direction latch 26.
Supplied to 33. The frequency divider 32 changes the frequency division ratio to a higher value in accordance with the instruction for deceleration. For example, the reference signal is generated at a fraction or several tens of minutes compared to the reference signal at the time of normal rotation. Also, the speed discriminator 33 receives the input FG
The signal and the reference signal are compared, and a deceleration signal is generated when the FG signal is larger than the reference signal. This deceleration signal is generated as a pulse signal having a pulse length corresponding to the difference between the FG signal and the reference signal. The matrix circuit 14 performs control to supply a deceleration signal to the coils 1, 2, and 3 based on a direction signal, a speed signal, and the like.

When the frequency division ratio of the frequency divider 28 is changed, the FG signal is changed. Therefore, when other conditions are kept constant, the rotation speed of the motor is changed.

In the circuit shown, R represents a resistor, C represents a capacitor, and D represents a diode.

FIGS. 2A and 2B are a circuit diagram extracting and showing a main part of the motor control circuit of FIG. 1, and an output voltage waveform of a discriminator.

The speed discriminator circuit 33 is supplied with an FG signal indicating the rotation of the rotor and a reference signal. Here, different reference signals are supplied depending on whether the motor is rotated at a normal constant speed or decelerated. By comparing the FG signal with the reference signal, the discriminator 33 generates an output signal having a pulse length according to the difference. At the time of constant speed rotation, when the FG signal is lower than the reference signal, a control signal for accelerating is generated. On the other hand, in the case of the deceleration mode, a control signal for performing deceleration is generated when the FG signal is higher than the reference signal. The output signal of the discriminator 33 has a pulse length corresponding to the difference from the reference signal,
The integration is performed by the integration circuit 36. The integrated voltage is compared with the reference voltage Vref by the integrating amplifier 35 to generate an acceleration or deceleration signal.

The discriminator 33 generates a positive pulse when in the constant speed rotation mode (when the FG signal is lower than the reference signal), and when in the deceleration mode, as shown in FIG. 2B, for example. Generates a negative pulse (when the FG signal is higher than the reference signal).

That is, the circuit controls the motor so that the rotation of the rotor matches the rotation represented by the reference signal. Therefore, at the time of deceleration, the reference signal is set to a value sufficiently lower than the reference signal at the time of constant speed rotation. The reference signal at the time of deceleration is not limited to one, and may be a signal having a plurality of values that decrease with time.

Since the discriminator 33 generates a signal having a pulse length corresponding to the difference between the FG signal and the reference signal, when the rotation of the rotor approaches the target rotation, the reverse rotation torque can be reduced. . In this way, smooth and rapid acceleration and deceleration can be performed.

FIG. 3 shows a flowchart of control of the deceleration operation according to the above embodiment.

When a brake command is generated from the normal rotation (S1) (S2), a reverse rotation torque is generated (S3), and the rotor is braked. On the other hand, the reference clock signal is changed (S4), and the criterion of the discriminator is changed (S5). Based on the changed reference, the discriminator determines the current situation and performs torque control according to the rotation speed (S6). When the rotation of the rotor decreases to a constant value due to deceleration, a brake release command is issued (S7),
The motor is stopped (S8).

In this way, by changing the circuit function based on the direction signal, acceleration and deceleration can be performed using the same circuit.

Although the case where the frequency of the FG signal is directly compared with the frequency of the reference signal has been described, the reference signal may be any signal that can be used for determining the frequency of the FG signal. For example, FG
The signal may be compared by dividing one of the reference signal and the reference signal, or the frequency may be compared by fV conversion into a voltage.

Although the present invention has been described with reference to the embodiments, the present invention is not limited thereto. For example, it will be apparent to those skilled in the art that various modifications, improvements, combinations, and the like can be made.

[Effects of the Invention] As described above, according to the present invention, motor control can be efficiently performed with a simple configuration.

The deceleration control can be performed using the motor acceleration control circuit. By sharing a part of the circuit, efficient deceleration control can be performed with a simple configuration.

[Brief description of the drawings]

FIG. 1 is a circuit diagram of a motor control circuit according to an embodiment of the present invention. FIGS. 2 (A) and 2 (B) are circuit diagrams and signal waveforms showing main parts of the circuit of FIG. 1, and FIG. 2 is a flowchart for explaining the control operation of the circuit of FIG.

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Claims (1)

(57) [Claims] An FG signal source for detecting rotation of a rotor of a motor to derive an FG signal, a reference clock signal for rotation, and a reference clock signal for deceleration having a higher frequency than the reference clock for rotation. And a means for generating a rotation or deceleration instruction signal. When a rotation is instructed, the FG signal is compared with a rotation reference clock signal, and when the FG signal is lower than a predetermined frequency, acceleration is performed. When the deceleration command is issued, the FG signal is compared with the deceleration reference clock signal, and when the FG signal is higher than a predetermined frequency,
A discrimination circuit for generating a deceleration signal composed of a pal signal having a pulse length corresponding to a difference between the FG signal and the reference clock signal for deceleration.