JP3103757U - DC motor rotation speed control (ON / OFF control) - Google Patents

Abstract

A circuit for controlling a rotation speed of a DC motor is provided.
An encoder is attached to a motor, the number of pulses generated by the encoder in a predetermined time is counted by a counter IC, and the set number of pulses is compared with a magnitude comparison IC. Turns off the motor (brakes the motor) and turns on the motor (flows current to the motor) if the number of pulses is smaller than the set value. By repeating ON and OFF in this manner, the number of pulses generated by the encoder within a certain time is maintained within a certain range. Thus, the rotation speed of the motor is kept constant.
[Selection diagram] Fig. 1

Description

Detailed description of the invention

It is intended to control the rotation speed of a DC motor with a simple digital circuit for timing an encoder and an IC (counter, size comparison, NAND, motor driver).

  For the DC motor, a method of changing the rotation speed by PWM is often used, but this method does not keep the rotation speed constant when the load changes. (This is because PWM only keeps the amount of current applied to the motor constant and does not change the amount of current according to the load.)

Digital circuit for controlling the rotation speed of DC motor using encoder / motor driver IC / counter IC and size comparison IC

Means for solving the problem (Description of circuit operation)

  Attach an encoder to the motor, count the number of pulses generated by the encoder in a fixed time with the counter IC, compare it with the set number of pulses with the magnitude comparison IC, and if the number of pulses from the encoder is larger than the set value, turn on the motor. Turn OFF (brake the motor), and if the number of pulses is smaller than the set value, turn the motor ON (flow current to the motor). By repeating ON and OFF in this manner, the number of pulses generated by the encoder within a certain time is maintained within a certain range. Thus, the rotation speed of the motor is kept constant.

Next, an example will be described more specifically. (See Fig. 1) (Note 1)
In this example, the rotation speed of the motor is maintained at 500 rpm.
(Note 2) It is assumed that the encoder generates one pulse per rotation of the motor.
(Note 3) The frequency of the oscillation circuit is assumed to be 100 Hz (period is 10 milliseconds)

  (Circuit example 1) This is a circuit example using (74 161) as a counter IC and one (Comparator 7485) as a magnitude comparison IC.

FIG.

  Circuit for setting the timing (all figures) The output pulse from the encoder is input to the clock of the counter, and the output of the counter is input to the magnitude comparison IC to compare with the set value. (1) or A <B is “1”), which is always present, and is a circuit that takes the timing to determine when to read it and turn the motor on and off. (A) (b) (c) (d) ) And are detailed in FIGS. 3 to 6.

FIG.

  (A) Circuit for Determining Timing of Reading Comparison Result (Explanation of Circuit for Obtaining Timing to Compare (Take Signal from Large / Small Comparison IC)) A is a rectangular pulse from the oscillation circuit. By the integration circuit of the resistor and the capacitor and the NAND, an impulse waveform such as d 'which captures the rising edge of the waveform of A is obtained. 3. this

FIG.

At this timing, the signal from the comparison IC is read and held by the FF until the next rise of the pulse from the oscillation circuit. (In the previous example, 10mm seconds)

FIG.

  (B) Comparison result holding circuit (hold until the next oscillation circuit pulse rise) g goes to the motor driver by motor ON / OFF signal. Motor rotation when "1". Motor is braked when "0". .

FIG.

  (C) Timing circuit for clearing the counter to 0 At the rising edge of the rectangular pulse of C in (a), a signal for resetting the counter to 0 is generated by a differential circuit of a capacitor and a resistor. The time when the pulse C falls is coincident with the time when the comparison ends (the fall of d '). The two inverters are used to slightly delay the timing of waveform shaping and clearing the counter to zero.

FIG.

  (D) Processing circuit when RIPPLE CARRY occurs (to ignore the output signal of the size comparison IC when RIPPLE CARRY occurs) When all the outputs of the counter become "1" (when RIPPLE CARRY occurs), the following processing is performed. The output of the counter returns to 0 by the clock input. If the output of the comparison IC is taken at that time, A <B becomes “1”, which is different from the fact. In order to avoid this, the fact that the RIPPLE CARRY has occurred is stored in a flip-flop (FF) until the next pulse for setting the counter to 0 comes. That is, the FF is reset again by the next counter clear signal (common to (1)).

FIG.

  (Circuit example 2) (When it is desired to increase the control accuracy) Using two counter ICs (74 161) and two size comparison ICs (74 85), increasing the frequency of the oscillation circuit and the resolution of the encoder This is an example of a circuit that improves accuracy. (Thus, the accuracy can be improved by increasing the number of counter ICs and comparison ICs.)

Explanation of reference numerals

  1. FF: Flip prop (RS latch)

・ディップスイッチ等により２進数で設定する
今仮に ５ （０１０１）を 設定する
（モーターの回転速度を５００ｒｐｓにするため）

（カウンターはエンコーダーからのパルス数をカウントする）
・発振回路のパルスの立ち上がりで、▲４▼の比較をした後０にクリアする。

・発振回路の次のパルスの立ち上がり（１０ｍｓ経過）で▲４▼に進む。

（注） ▲１▼から▲４▼の動作を繰り返す。
【図面の簡単な説明】
【図１】【実施例】 （回路例１）
カウンターＩＣとして（７４ １６１）、大小比較ＩＣとして（コンパレータ ７４
８５）を各１個使って構成した回路例である。
【図２】タイミングをとるための回路（全図）
エンコーダーからの出力パルスをカウンターのｃｌｏｃｋに入れ、さらにカウンターの
出力を大小比較ＩＣに入れ、設定値と比較しているが、比較結果（Ａ＞Ｂが「１」か又は
Ａ＜Ｂが「１」か）は、常時でているので、何時それを読み出しモーターをＯＮ ＯＦＦ
させるかを決めるためのタイミングをとる回路
（イ）（ロ）（ハ）（ニ）と分け、図３から図６で、詳細化した。
【図３】（イ） 比較結果を読みとる時期を決める回路
（比較する（大小比較ＩＣから信号をとる）タイミングを得る回路の説明）
１．Ａは、発振回路からの矩形パルス
２．抵抗とコンデンサーの積分回路とＮＡＮＤによりｄ′のようなＡの波形の立ち上がり
を捉えたインパルス波形が得られる。
３．これを【図４】の（ロ）に送りこのタイミングで比較ＩＣからの信号を読みとりＦＦ
で発振回路からのパルスの次の立ち上がりまで保持する。（前の例では１０ｍｍ秒間）
【図４】（ロ） 比較結果の保持回路
（次の発振回路のパルスの立ち上がりまで保持する）
ｇはモーターＯＮ、ＯＦＦ信号でモータードライバーへ行く
「１」の時モーター回転 「０」の時モーターにブレーキがかかる。
【図５】（ハ） カウンターを０にクリアするタイミング回路
（イ）のＣの矩形パルスの立ち上がりで、カウンターを０にする信号をコンデンサーと抵
抗の微分回路で作り出している。
Ｃのパルスの立ち下がる時点は比較が終わる時点（ｄ′の立ち下がり）と一致している
。
２個のインバーターは波形の整形とカウンターを０にクリアするタイミングを少し遅ら
すためのものである。
【図６】（ニ） ＲＩＰＰＬＥ ＣＡＲＲＹが起こった時の処置回路
（ＲＩＰＰＬＥ ＣＡＲＲＹが起こった場合、大小比較ＩＣの出力信号を無視するため）
カウンターの出力が全て「１」になると（ＲＩＰＰＬＥ ＣＡＲＲＹが起こると）次のク
ロック入力でカウンターの出力は０に戻ってしまう。その時点で比較ＩＣの出力をとると
、Ａ＜Ｂが「１」になり、事実と違うことになる。
これをさけるため、ＲＩＰＰＬＥ ＣＡＲＲＹが起こったことを次にカウンターを０にす
るパルスが来るまでフリップフロップ（ＦＦ）で記憶しておく。
すなわち、次のカウンタークリア信号（▲１▼と共通）でＦＦは又リセットされる。
【図７】【実施例２】 （回路例２）
（制御の精度を上げたいとき）
カウンターＩＣ（７４ １６１），大小比較ＩＣ（７４ ８５）を各２個使用し、発振
回路の周波数と、エンコーダーの分解能をあげて、制御の精度を向上を図った回路の例で
ある。
（このように、カウンターＩＣと比較ＩＣの数を増やすことにより、精度を上げること
ができる。）
【符号の説明】
１． ＦＦ・・・フリッププロップ（ＲＳラッチ）[Document name] Description [Title of invention] DC motor rotation speed control (ON / OFF control)
[Detailed description of the invention]
[0001]
【Technical field】
The rotation speed control of DC motor is controlled by encoder and IC (counter, size comparison, NAND,
It's a simple digital circuit to get the timing with the motor driver).
[0002]
[Background Art]
For the DC motor, a method of changing the rotation speed by PWM is often used, but this method does not keep the rotation speed constant when the load changes. (This is because PWM only keeps the amount of current applied to the motor constant and does not change the amount of current according to the load.)
[0003]
[Disclosure of Invention]
[Problems to be solved by the invention]
Digital circuit for controlling rotation speed of DC motor using encoder / motor driver IC / counter IC and size comparison IC
[Means for Solving the Problems (Description of Circuit Operation)]
Attach an encoder to the motor, count the number of pulses generated by the encoder in a fixed time with the counter IC, compare it with the set number of pulses with the magnitude comparison IC, and if the number of pulses from the encoder is larger than the set value, turn on the motor. OFF (brake the motor)
If the number of pulses is smaller than the set value, the motor is turned on (current is supplied to the motor). By repeating ON and OFF in this manner, the number of pulses generated by the encoder within a certain time is maintained within a certain range. Thus, the rotation speed of the motor is kept constant.
[0005]
Next, an example will be described more specifically. (See Fig. 1)
(Note 1) In this example, the rotation speed of the motor is maintained at 500 rps.
(Note 2) It is assumed that the encoder generates one pulse per rotation of the motor.
(Note 3) The frequency of the oscillation circuit is assumed to be 100 Hz (period is 10 milliseconds)

・ Set in binary notation with DIP switch etc. Temporarily set 5 (0101)
(To make the motor rotation speed 500 rps)

(The counter counts the number of pulses from the encoder.)
・ At the rising edge of the pulse of the oscillation circuit, clear to 0 after comparing (4).

・ Proceed to (4) at the rise of the next pulse of the oscillation circuit (elapse of 10 ms).

(Note) The operations from (1) to (4) are repeated.
[Brief description of the drawings]
FIG. 1 [Example] (Circuit example 1)
As a counter IC (74 161), as a magnitude comparison IC (comparator 74
85) is an example of a circuit configured using one each.
FIG. 2 is a circuit for taking timing (all diagrams)
The output pulse from the encoder is input to the clock of the counter, and the output of the counter is input to the magnitude comparison IC to compare with the set value. The comparison result (A> B is “1” or A <B is “1” ) Is always on, so read it and turn the motor on / off
Circuits that take timings to determine whether to make them (a), (b), (c), and (d) are detailed in FIGS. 3 to 6.
FIG. 3 (a) Circuit for determining timing for reading comparison result (Explanation of circuit for obtaining timing for comparing (taking a signal from size comparison IC))
1. A is a rectangular pulse from the oscillation circuit. By the integration circuit of the resistor and the capacitor and the NAND, an impulse waveform such as d 'which captures the rising edge of the waveform of A is obtained.
3. This is sent to (b) of FIG. 4 to read the signal from the comparison IC at this timing and read the FF
Hold until the next rise of the pulse from the oscillation circuit. (10mm in the previous example)
FIG. 4B is a comparison result holding circuit.
(Hold until the next oscillation circuit pulse rises)
g goes to the motor driver with the motor ON / OFF signal. When "1", the motor rotates. When "0", the motor is braked.
FIG. 5 (c) Timing circuit for clearing the counter to 0 A signal for resetting the counter to 0 at the rise of the rectangular pulse of C in (a) is generated by a capacitor and resistor differentiating circuit.
The time when the pulse C falls is coincident with the time when the comparison ends (the fall of d ').
The two inverters are used to slightly delay the timing of waveform shaping and clearing the counter to zero.
FIG. 6 (d) Treatment circuit when ripple carry occurs (to ignore the output signal of the magnitude comparison IC when ripple carry occurs)
When all the outputs of the counter become "1" (when RIPPLE CARRY occurs), the output of the counter returns to 0 at the next clock input. If the output of the comparison IC is taken at that time, A <B becomes “1”, which is different from the fact.
To avoid this, the fact that the RIPPLE CARRY has occurred is stored in a flip-flop (FF) until the next pulse for setting the counter to 0 comes.
That is, the FF is reset again by the next counter clear signal (common to (1)).
FIG. 7 [Example 2] (Circuit example 2)
(To increase control accuracy)
This is an example of a circuit in which two counter ICs (74 161) and two large and small comparison ICs (7485) are used, and the frequency of the oscillation circuit and the resolution of the encoder are increased to improve control accuracy.
(Thus, the accuracy can be improved by increasing the number of counter ICs and comparison ICs.)
[Explanation of symbols]
1. FF: Flip prop (RS latch)

Claims (1)

  Digital circuit for moving each IC with good timing when controlling the rotation of DC motor using encoder / IC (IC for counter, size comparison, NAND, motor driver, etc.) and oscillation circuit for obtaining a certain time

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