JPH04355690A - Dc motor control system - Google Patents

Abstract

PURPOSE:To control the rotational speed of a rotating object with high accuracy by calculating the modifying amount of the pulse width of a driving pulse to be applied on a DC motor according to the torque curve of the DC motor. CONSTITUTION:Upon receiving a phase difference value specifying the modifying amount of the rotational speed of a DC motor 1 from a digital filter 6, a correcting circuit 9 calculates a modifying amount of pulse width for realizing the modifying amount of rotational speed according to a torque curve being managed. Consequently, a PWM circuit 7 produces a drive pulse having pulse width corresponding to thus calculated modifying amount. A power amplifier 8 then delivers the drive pulse from the PWM circuit 7 to the DC motor 1 thus controlling the rotational speed of a rotary object 2. According to the invention, rotational speed of the rotating object 2a can be controlled with high accuracy.

Description

[Detailed description of the invention]

0001

[Field of Industrial Application] The present invention relates to a DC motor control method for controlling a DC motor used to control the rotation of a rotating object, and more particularly to a DC motor control method that allows highly accurate control of the rotational speed of a rotating object. It is related to the method.

0002

[Prior Art] As a method for controlling the rotational speed of a rotating object using a DC motor, the DC motor is controlled according to the phase difference between an index signal detected from the rotating object and a reference signal generated by a reference signal generator. Some devices control the drive pulse by determining the pulse width of the applied drive pulse.

FIG. 4 shows a conventional configuration of this control system. Here, this figure shows an example in which the rotational speed of the disc-shaped recording medium 2 is controlled using the DC motor 1. As shown in this figure, conventionally, an index signal is extracted from the reproduced signal waveform obtained by the detection signal from the magnetic head 3, and a phase difference comparator 5 compares the rising edge of the extracted index signal with a crystal oscillator 4. The phase difference between the rising edge of the reference clock signal (which defines the desired rotational speed of the disc-shaped recording medium 2) generated by the disc-shaped recording medium 2 is detected. The phase difference detected at this time corresponds to the fact that the reference clock signal generated by the crystal oscillator 4 defines the desired rotational speed of the disk-shaped recording medium 2, and the difference between the desired rotational speed and the actual rotational speed. It represents the displacement difference between the rotation speed and the rotation speed. From this point on, conventionally, assuming that there is a proportional relationship between the pulse width of the drive pulse applied to the DC motor 1 and the rotational speed of the DC motor 1 at that time, the digital filter 6 is used to detect the phase difference comparator. After filtering the phase difference detected by 5, the PWM circuit 7 generates a driving pulse having a pulse width value that is proportional to the level value of this filtered signal, and the driving pulse is outputted via the power amplifier 8. , the rotational speed of the disk-shaped recording medium 2 is controlled by applying the generated drive pulses to the DC motor 1.

0004

[Problems to be Solved by the Invention] Conventionally, it has been assumed that there is a proportional relationship between the pulse width of the drive pulse applied to the DC motor 1 and the rotational speed of the DC motor 1 at that time. , the pulse width of the drive pulse given to the DC motor 1 was determined and controlled. However, the reality is that a proportional relationship does not hold between the pulse width of the drive pulse applied to the DC motor 1 and the rotational speed of the DC motor 1 at that time. In other words, even if the pulse width of the drive pulse is controlled by the PWM circuit 7 to increase or decrease the rotation speed by a predetermined amount according to the comparison result of the phase difference comparator 5, the reality is that the desired rotation speed cannot be achieved. be.

[0005] Accordingly, in the prior art, when controlling the rotational speed of a rotating object using a DC motor, there has been a problem in that the rotational speed of the rotating object cannot be controlled with high precision. The present invention has been made in view of such circumstances, and
An object of the present invention is to provide a new DC motor control method that enables highly accurate control of the rotational speed of a rotating object when controlling the rotational speed of the rotating object using a DC motor.

[0006]

[Means for Solving the Problems] FIG. 1 illustrates the basic configuration of the present invention. In the figure, 1 is a DC motor, 2a is a rotating object whose rotation is controlled by the DC motor 1, and 3
A is a detection end that detects an index signal detected from the rotating object 2a, and 4a is a reference signal generator that generates a reference signal that defines the desired rotational speed of the rotating object 2a. 5 is a phase difference comparator which detects the phase difference between the rising edge of the index signal detected by the detection end 3a and the rising edge of the reference signal generated by the reference signal generator 4a; 6; 9 is a digital filter that reduces the phase difference value calculated by the phase difference comparator 5 in stages; 9 is a correction circuit;
7 is a PWM controller that manages the torque curve of the DC motor 1 and calculates the amount of change in the pulse width of the drive pulse given to the DC motor 1 according to the torque curve when a phase difference value is given from the digital filter 6; A circuit that generates a drive pulse having a pulse width value corresponding to the amount of change calculated by the correction circuit 9; 8 is a power amplifier that outputs the drive pulse generated by the PWM circuit 7 to the DC motor 1;
The rotational speed of the rotating object 2a is controlled by applying the same to the rotational speed of the rotating object 2a.

[0007]

[Operation] In the present invention, the newly provided correction circuit 9 manages the nonlinear torque curve established between the pulse width of the drive pulse applied to the DC motor 1 and the rotational speed of the DC motor 1 at that time. With this configuration, when a phase difference value specifying the amount of change in the rotation speed of the DC motor 1 is given from the digital filter 6, the amount of change in the pulse width of the drive pulse given to the DC motor 1 is determined according to the torque curve managed by the digital filter 6. Adopt a configuration to calculate. From now on, it will be possible to control the rotational speed of the line object 1 with high precision.

[0008]

EXAMPLES The present invention will be explained in detail below according to examples. FIG. 2 shows an example of a torque curve managed by the correction circuit 9 described in FIG. 1. In the figure, the horizontal axis represents the amount of change in the pulse width of the drive pulse applied to the DC motor 1, expressed as a percentage, and the vertical axis represents the amount of DC generated when applying the drive pulse with the amount of change in pulse width. The amount of change in the rotation speed of the motor 1 is expressed in percentage.

FIG. 3 shows specific numerical values on the torque curve of FIG. 2. As shown in this figure, the torque curve shows that, for example, in order to increase the rotational speed of the DC motor 1 by 1%, it is necessary to increase the pulse width of the drive pulse applied to the DC motor 1 by 1.12%. There is a DC motor 1
In order to reduce the rotation speed of DC motor 1 by 1%,
It is necessary to reduce the pulse width of the drive pulse given to the DC motor 1 by 1.24%, which holds between the pulse width of the drive pulse given to the DC motor 1 and the rotational speed of the DC motor 1 at that time. It manages nonlinear data relationships.

[0010] The correction circuit 9 manages this torque curve, and when a phase difference value specifying the amount of change in the rotation speed of the DC motor 1 is given from the digital filter 6, the correction circuit 9 adjusts the rotation speed according to the managed torque curve. The amount of change in pulse width that realizes the amount of change is calculated, and in response to this calculation process, the PWM circuit 7 generates a drive pulse having a pulse width value according to the amount of change calculated by the correction circuit 9, and After receiving the treatment,
The power amplifier 8 controls the rotational speed of the rotating object 2a by applying drive pulses generated by the PWM circuit 7 to the DC motor 1.

As described above, in the prior art, as shown by the broken line data in FIG. 2, there is a proportional relationship between the pulse width of the drive pulse applied to the DC motor 1 and the rotational speed of the DC motor 1 at that time. In contrast, in the present invention, the pulse width of the drive pulse given to the DC motor 1 is determined and controlled based on the assumption that the width of the drive pulse given to the DC motor 1 is determined. Since the configuration is adopted to calculate the amount of change in the pulse width of the drive pulse applied to the line object 1, the rotational speed of the line object 1 can be controlled with high precision.

0012

[Effects of the Invention] As explained above, according to the present invention,
When controlling the rotational speed of a rotating object using a DC motor, it becomes possible to control the rotational speed of the rotating object with higher precision than in the past.

[Brief explanation of drawings]

FIG. 1 is a diagram showing the principle configuration of the present invention.

FIG. 2 is an example of a torque curve managed by a correction circuit.

FIG. 3 is a numerical example of a torque curve managed by a correction circuit.

FIG. 4 is an explanatory diagram of the prior art.

[Explanation of symbols]

1 DC motor 2 Disk-shaped recording medium 2a Rotating object 3 Magnetic head 3a Detection end 4 Crystal oscillator 4a Reference signal generator 5 Phase difference comparator 6 Digital filter 7 PWM circuit 8 Power amplifier 9 Correction circuit

Claims (1)

[Claims] 1. The pulse width of a drive pulse for driving the DC motor is controlled according to the phase difference between an index signal detected from a rotating object controlled by the DC motor and a reference signal generated by a reference signal generator. a correction circuit (9) that manages a torque curve of the DC motor and calculates an amount of change in the pulse width of the drive pulse according to the torque curve when the phase difference is given; A DC motor characterized in that the rotating object is controlled to a desired rotational speed state by controlling the pulse width value of the drive pulse according to the amount of change calculated by the correction circuit (9). control method.