JPS5963992A - Positioning controller for dc motor - Google Patents

Abstract

PURPOSE:To improve the resolution of a DC motor control circuit of a pulse width modulation type by composing the control circuit of a digital circuit, thereby eliminating a D/A converter. CONSTITUTION:An error counter 2 outputs an error pulse number N and rotating direction information RD in response to the instruction pulse from a controller 1 and moving amount of a target from an encoder 8. A counter 12 counts the outputs of an oscillator 11, repeats zero - the maximum value, and a digital counter 10 compares the output of the counter 2 with the output of the counter 12. FF14 is set by the output of a 0 detector 13 for detecting that the output of the counter 12 is 0, and reset by the coincidence output of the comparator 10. A power circuit 6 controls the polarity and the time of a current flowed through a DC motor 7 in response to the output pulse width and the rotating direction information RD of the FF14.

Description

DETAILED DESCRIPTION OF THE INVENTION Field 51 of the Invention The present invention relates to a pulse width modulation DC motor positioning control device.

Background of the Technology Direct current (IJC) motors are widely used in rivet motors and the like because of their higher speed, higher efficiency, and lower vibration than pulse motors, and there are many positioning devices using them. In this case, I) Pulse l1 is used to control the rotation angle of the C motor.
vii modified #J1 (PWM) method may be used.

Conventional technology and problems Figure 1 shows a conventional example of this, in which a movement amount command (number of up pulses UP or down pulses DP) is given to the l, 9, and -bo systems.
The controller 2 outputs the movement amount command, that is, the number of pulses, from the 21 controller l, and the direction determination circuit 9
3 is a differential counter that counts down the up/down pulses UP/DP from UP/DP, 3 is a converter that converts its output into an analog value, 4 is a circuit that generates a reference triangular wave, 5 is a An analog comparator that generates a pulse width modulated output in the form of slicing and shaping the output waveform of the reference triangular wave generator 4 at the analog output level of the 821 inverter 3; 6 is the pulse width and error counter; PWM type (Menoff type) power p t/3 that receives the rotation direction 1η information RI) from 2 and controls the rotation angle of the DC motor 7.
．． 7 is a DC motor that positions the object, 8 is an encoder directly connected to the motor shaft, and 9 receives two-phase output pulses from the encoder to detect the rotation direction, and generates up/down pulses for each rotation direction. This is a direction determining circuit that outputs UP/DI'.

In the wooden board system, when the number of up-trI command pulses UP or the number of down-specified pulses DP is output from the main unit, the error continues until the direction discrimination circuit 9 outputs the same number of pulses UP or DP. Counter 2 produces an output,
The DC motor 7 continues to rotate.

In other words, at the time when the number of command pulses is output from J-L, there is no input from the direction discrimination circuit 9, and the error counter 2 receives the command value itself (if it is too large, it is saturated). ), a wide pulse corresponding to the output is applied to the motor 7, and the motor starts rotating with a large torque,
When an amplifier or down pulse UP or DP is input from the direction discrimination circuit 9 due to this rotation, the error counter 2 subtracts it and gradually decreases the output. 1) The Δ converter 3 converts it into analog, and the analog comparator 5 generates a pulse corresponding to the output of the error counter 2, which is applied to the motor 7 via the power circuit 6. This progresses to zero error. The error counter 2 also calculates l) C depending on the number of command pulses from the controller I and the sign of the error.
Since it is possible to determine in which direction the motor 7 should be rotated to correctly position the object to the target position, the rotation direction information is provided to the power circuit 6. The power circuit 6, which receives the rotational direction information RD and the pulse width of "1," controls the polarity and time of the current supplied to the DC motor 7 to rotate the motor. The amount of movement of this condensed object is detected by the encoder 8, and the above-mentioned control is repeated until the output pulses of the direction determining circuit 9 match the number of output pulses of the controller l.

Since the pulse width modulation part of the above method is an analog type, (1) it is expensive; A:1 inverter is required; even if an attempt is made to reduce +211i degrees by -l, the D A = 16 bisoto or more; Disadvantages include: R converters are difficult to obtain (not commercially available), (3) Analog models require many adjustments such as zero adjustment, and (4) It is difficult to convert into customer ICs (adopting gate play). There is.

OBJECTS OF THE INVENTION The present invention seeks to provide a PWM type DC motor control system that eliminates the above-mentioned drawbacks by being configured with a purely digital circuit.

Structure of the Invention The present invention provides an output of a DC motor rotation amount detection circuit and a controller I.
・An error counter that outputs a numerical value and rotation direction information corresponding to the error with the movement amount command from the roller, and n1 that repeats between zero and maximum values using the output pulse of the reference oscillator as an argument.
a second counter that outputs a numerical value; a flip-flop that is set when the first value of the second counter becomes zero; and a flip-flop that is set when the output of the error counter and the output of the second counter match. and a digital comparator that produces an output for resetting the DC motor, the output of the flip-flop and the rotation direction information are added to a power circuit, and the output is used to control the rotation amount of the DC motor. This feature will be described in detail below with reference to the illustrated embodiment.

Embodiment of the Invention FIG. 2 shows an embodiment of the present invention, in which the same parts as in FIG. 1 are denoted by the same reference numerals. This example is different from FIG.
, counter 12.0 detector 13, flip-flop 14
The point is that it has been replaced with . The counter 12 counts the output of the oscillator 11 to 61, and its δ1 value which repeats 1, 0, to the maximum value is compared with the output N of the error counter 2 by the digital comparator IO.

The 0 detector 13 detects that the output of the counter 12 is () and sets the ``ζ'' Fritsop filter 14.

The flip 1 and 1 knobs 14 are reset by:
Since it is a coincidence output of comparator 10, flip-flop 1
4's output pulse width W (set period) and its period], where the output of oscillator 11 is f (TIZ), the number of bits of counter 12 is M, and the output of error counter 2 is N, W = N/f T=2/r. Therefore, the average pulse width (mark rate) W of the output of the flip-flop 14 is as follows, which is proportional to the difference between the output of the analog comparator 5 in FIG. Also, since it is related to the output frequency f of the oscillator 11, it is not affected by the accuracy of the starting oscillator.

FIG. 3 is a time chart 1 for explaining the operation when M=4 and N=IO. Q o "Q 3 indicates the output of each stage of the 4-bit counter 12, and S indicates the output of the detector 13.
This occurs every time the output of the counter 12 becomes 15.

R is the coincidence output of comparison 'a10, which occurs every time the count FI+number becomes 9. DV is the output of the Frisobuf knob 14, which is set and reset by S and R, and becomes a rectangular wave as shown in the figure.

Of course, N is not constant, but decreases every moment towards O, so the pulse 11lii of the output DV of the flip-flop 14
gradually decreases and becomes zero at the target position. Positioning is performed using this.

The highest position 1- of the error counter 2 is used to indicate the polarity (direction of rotation), and is inverted when the count value exceeds 0, so that an over-travel return operation can be performed. Error counter 2, digital comparator lO, counter I
The bit number M of 2 is the same, and the resolution of the servo system is determined by this bit number M. In other words, the resolution is l/2
” Thank you, if M=8, it is 1/256, M-16
If so, it becomes 1/655313. This corresponds to the resolution of the conventional D converter 3, but the difference from the conventional one is M
The point is that the resolution can be improved simply by increasing -U.

If the number of bits M of the counter 12 is constant, the generator 1
The frequency f of 1 influences the frequency of the mother line (7C), that is, the higher the value of f, the better, but the limit is limited by the switching speed of the power circuit 6.

Effects of the Invention: As stated above, according to the present invention, 1) of the PWM method
Since the C'F: -ta control circuit is constructed with a digital circuit, (11 crystal value or AJ inverter is not required, (2)
It has the following advantages: resolution can be sufficiently increased, (3) there are no adjustment points, and (1) data can be integrated into customer ICs.

[Brief explanation of the drawing]

1st F! ! 1 is a block diagram of a conventional PWM type DC motor control device, 21st page 1 is a block diagram showing an embodiment of the present invention, and FIG. 3 is a time chart showing its operation. In the figure, 1 is the controller, 2 is the error counter, and 6 is the PW.
M type power circuit, 7 is DC motor, 8 is encoder, 9
10 is a direction discrimination circuit, 10 is a digital comparator, 11 is an oscillator, 12 is a second counter, 13 is a 0 detector, and 14 is a flip-flop. Applicant Fujitsu Co., Ltd. Representative Patent Attorney Minoru Aoyagi

Claims (1)

[Claims] An error counter that outputs a count value and rotation direction information according to the error between the output of the DC motor rotation amount detection circuit and the transfer 1IiIJ amount command from the controller, and an error counter that counts the output pulses of the crystal quasi oscillator to zero and maximum values. a '2nd counter that outputs the d1 value that repeats the interval, and the Fi of the second counter;
a flip-flop that is set when the l value becomes zero; and a digital comparator that produces an output that resets the flip-flop when the output of the error counter and the output of the second counter match; A DC motor positioning control device using a pulse width modulation method, characterized in that the output of the DC motor and the rotation direction information are added to a power circuit, and the rotation amount of the DC motor is controlled by the output.