JPH04251594A - Motor drive controller - Google Patents

Abstract

PURPOSE:To provide a motor controller in which current control range can be widened by switching the current resolution according to the current range. CONSTITUTION:The motor drive controller comprises a first circuit for dividing a predetermined reference voltage Vref by a divisor designated by an output signal from a control circuit 10 comprising a microprocessor and a second circuit for reducing the output signal from the first circuit with a damping rate designated by an output signal from the control circuit. Output from the second circuit is fed to a drive circuit 15 and the current resolution of the driving current of a motor 16 is determined by the first circuit while the current range is determined by the second circuit.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention relates to a motor drive control device that calculates a motor control drive current using a microprocessor and drives the motor at a constant current based on the result of the calculation. This invention relates to a motor control device that can be used in a wide range of applications.

0002

[Prior Art] Conventionally, as a motor drive control device that requires extremely wide current control, such as a head actuator drive motor used for high-speed access to magnetic disk memory, current resolution is switched between track following and seek. There is.

There is also a method of expanding the current range by adding a set current range offset while maintaining the resolution of the digital-to-analog converter, as in the drive control device disclosed in Published Practical Application No. 69597/1983.

0004

[Problem to be Solved by the Invention] However, the method of switching the current resolution between track following and seeking is difficult to control with such two-step current resolution switching in high-speed seeking of magnetic disk memory with high track density. There is a problem with becoming.

[0005] In addition, the method of expanding the current range by adding the set current range offset while maintaining the resolution of the digital-to-analog converter requires highly accurate adjustment of the set offset value, and the current Although high resolution is not required when the current value is large, the control device is complicated and expensive because it uses the same high resolution even when the current value is large as when the current value is small.

The present invention has been made in view of the above points, and an object of the present invention is to provide a motor control device that can widen the control current range by switching the current resolution depending on the current range.

[0007]

[Means for Solving the Problems] In order to solve the above problems, the present invention converts a motor drive current signal output as a digital signal from a control circuit equipped with a microprocessor into an analog signal, and converts the converted analog signal into an analog signal. A motor drive control device that drives a motor via a drive circuit includes a first circuit that divides and outputs a predetermined reference voltage by a division number specified by an output signal from the control circuit; a second circuit that reduces the output at an attenuation rate specified by the output signal from the control circuit and outputs the reduced output, the output of the second circuit is configured to be input to the drive circuit, and the motor is driven. The current resolution of the current is determined by the first circuit, and the current range is determined by the second circuit.

[0008]

[Operation] By configuring the motor drive control device as described above, the resolution is determined by the first digital-to-analog converter, and the current range is determined by the second digital-to-analog converter. The resolution is determined by the current range (switching the resolution according to the current range) allows for accurate control of the motor drive current where the current changes over a wide range, and a wide control current range can be obtained using a low bit count digital-to-analog converter. be able to. Furthermore, by manipulating the number of bits of the digital-to-analog converter, it is possible to easily deal with cases where high resolution is required or where the control range is widened.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Examples of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing the configuration of a motor drive control device according to the present invention. In FIG. 2 is a digital-to-analog converter, 14 is an operational amplifier, 15 is a power transistor, 16 is a DC motor, and 17 is a current detection resistor.

[0010] In the motor drive control device having the above configuration,
The first digital-to-analog converter 11 and the second digital-to-analog converter 13 are R-2R ladder type digital-to-analog converters, and the first digital-to-analog converter 11 is connected to the control circuit 1 through the bus B.
The reference voltage Vref is divided by the division number specified by the signal transmitted from 0 and output to the second digital-to-analog converter 13 via the operational amplifier 12. Further, the second digital-analog converter 13 attenuates the output from the first digital-analog converter 11 at an attenuation rate specified by a signal from the bus B, and outputs the output from the operational amplifier 14.
The signal is outputted to the power transistor 15 via. That is, the first digital-to-analog converter 11 uses the reference voltage Vr
The second digital-to-analog converter 13 is used as an attenuator and a current drive circuit.

The power transistor 15 drives the DC motor 16 with a current according to the output of the second digital-to-analog converter 13. That is, the transistors Tr1, Tr
When transistors Tr2 and Tr3 are turned on, the DC motor 16 is rotated in the forward direction, and when transistors Tr2 and Tr3 are turned on, the DC motor 16 is rotated in the reverse direction. The drive current of the DC motor 16 is detected by a current detection resistor 17 and fed back to the second digital-to-analog converter 13.

The current resolution of the current supplied to the DC motor 16 is determined by the first digital-to-analog converter 11, and the current range is determined by the second digital-to-analog converter 1.
3. The number of bits of these digital-to-analog converters is determined by the required resolution and current range.

[0013] An example will now be described in which the first digital-to-analog converter 11 and the second digital-to-analog converter 13 each consist of 8 bits. Output V11 of first digital-to-analog converter 11
can take a value from 0 to -Vref (reference voltage value), and its resolution is -Vref/256 [V/bit
]. This first digital-to-analog converter 1
1 is input to the second digital-to-analog converter 13 and the current Im flowing through the DC motor 16 is constant current driven.
The output is V13, and the resistance value of the current detection resistor 17 is R1.
7, Im=V11/256・V13/256・Vref/R
It becomes 17.

[0014] In motor control, high current resolution is not required for large drive currents. For this reason, the resolution is switched and used for the current value. In other words, the second
Using only the weighted resistance value, the value of the output V13 of the digital-to-analog converter 13 is calculated as follows: 1 2 3 4 5 6
7 82 ,2, 2, 2, 2,
When using eight types up to 2, 2, 2, the resolution drops by 1/2 when each setting range is exceeded, and the usable range can be doubled.

The conversion of the calculation result of the microprocessor of the control circuit 10 into the drive current of the DC motor 16 via the first digital-to-analog converter 11 and the second digital-to-analog converter 13 is determined by software. FIG. 2 is a diagram showing an example of the relationship between the calculation results of the microprocessor of the control circuit 10, the current resolution of the first digital-to-analog converter 11, and the current range of the second digital-to-analog converter 13. As shown, a first digital-to-analog converter 11
(DAC11) current resolution...4/256,
The current range of the second digital-to-analog converter 13 is reduced to 2/256, 1/256, and so on.
Can be doubled.

FIG. 3 is a block diagram showing another configuration of the motor drive control device of the present invention. This motor drive control device differs from the motor drive control device of FIG.
and that the operational amplifier 14 is used with a single power source. Therefore, the detected value of the motor drive current detected by the current detection resistor 17 is shifted by a predetermined level by the level shifter 18 and fed back to the second digital-to-analog converter 13.

FIG. 4 is a diagram showing an example in which the second digital-to-analog converter 13 is constructed as a discrete component. As shown in the figure, the output resistance group 20 of the first digital-to-analog converter 11, 0 1 2
n-1 n2 R, 2 R, 2 R...
..., 2R, 2R are selected by the analog multiplexer 21, and the power transistor 1 is selected through the operational amplifier 22.
It is configured to output to the base of 5.

FIG. 5 is a diagram showing an example in which the motor drive control device having the above configuration is used as an access device for a magnetic disk memory. As shown in the figure, a control circuit 50 including a CPU
The digital output of
AC) 51 converts it into a corresponding analog signal, and supplies it to the motor that drives the head 54 through a power amplifier (PA) 52. The motor 53 is driven depending on the magnitude of this supplied current, track information for which seek or track following is performed is fed back via a demodulator 56, and a position error signal (PES) is fed back via a demodulator 57. be done. As a result, the head 54 accesses the magnetic disk memory 55 based on the output from the control circuit 50.

In the magnetic disk memory access device having the above configuration, a digital-to-analog converter (DAC) is used.
) 51 and the power amplifier (PA) 52, the motor drive control unit composed of the first digital-to-analog converter 11, operational amplifier 12, second digital-to-analog converter 13, operational amplifier 14, etc. of the above embodiment is used. By doing so, it is possible to appropriately control the movement of the head 54 by switching the resolution in response to the motor control drive current that varies over a wide range as described above.

Although the above embodiment shows a case where the motor drive control device is applied to an access device for a magnetic disk memory, the present invention is not limited to this, and the motor control drive current varies over a wide range. It can be used as a motor drive control device for equipment.

[0021]

[Effects of the Invention] As explained above, according to the present invention, the current resolution is determined by the first digital-to-analog converter, and the current range is determined by the second digital-to-analog converter. Excellent effects can be obtained. (1) It is possible to configure a digital-to-analog converter with a small number of bits to obtain a wide control current range, and a low-cost motor drive control device can be provided. (2) By configuring the first digital-to-analog converter and the second digital-to-analog converter by one IC having two digital-to-analog converters, the mounting area can be reduced. (3) A control system with less variation in set current and a larger margin becomes possible. (4) When high resolution is required or when the control current range is widened, it can be set arbitrarily by manipulating the number of bits of the digital-to-analog converter.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the configuration of a motor drive control device of the present invention.

FIG. 2 is a diagram showing an example of the relationship between calculation results of a control circuit, current resolution, and current range.

FIG. 3 is a block diagram showing another configuration of the motor drive control device of the present invention.

FIG. 4 is a diagram showing an example in which the second digital-to-analog converter is configured as a discrete component.

FIG. 5 is a diagram showing an example in which the motor drive control device of the present invention is used in a magnetic disk memory access device.

[Explanation of symbols]

10 Control circuit 11 First digital-to-analog converter 12 Operational amplifier 13 First digital-to-analog converter 14 Operational amplifier 15 Power transistor 16
Motor 17 Current detection resistor 18
Level shift 20 Output resistance group 21 Analog multiplexer 22
operational amplifier

Claims (3)

[Claims] 1. A motor drive control device that converts a motor drive current signal output as a digital signal from a control circuit including a microprocessor into an analog signal, and drives a motor with the converted analog signal via a drive circuit. , a first circuit that divides and outputs a predetermined reference voltage by a division number specified by an output signal from the control circuit;
and a second circuit that reduces the output of the circuit at an attenuation rate specified by the output signal from the control circuit and outputs the result, and the output of the second circuit is configured to be input to the drive circuit. . A motor drive control device, wherein the current resolution of the motor drive current is determined by the first circuit, and the current range is determined by the second circuit. 2. The first circuit is a first digital-to-analog converter that divides and outputs a predetermined reference voltage by a division number specified by an output signal from the control circuit, and the second circuit is a 2. The motor drive control device according to claim 1, further comprising a second digital-to-analog converter that reduces the output of the first digital-to-analog converter at an attenuation rate specified by the output signal from the control circuit. 3. R-2 in at least a second digital-to-analog converter of the first digital-to-analog converter and the second digital-to-analog converter.
The motor drive control device according to claim 1, characterized in that an R-type digital-to-analog converter is used.