JPS6042707B2 - Back electromotive voltage amplification circuit for DC motor - Google Patents
Back electromotive voltage amplification circuit for DC motorInfo
- Publication number
- JPS6042707B2 JPS6042707B2 JP54136664A JP13666479A JPS6042707B2 JP S6042707 B2 JPS6042707 B2 JP S6042707B2 JP 54136664 A JP54136664 A JP 54136664A JP 13666479 A JP13666479 A JP 13666479A JP S6042707 B2 JPS6042707 B2 JP S6042707B2
- Authority
- JP
- Japan
- Prior art keywords
- motor
- voltage
- transistor
- back electromotive
- circuit
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02P—CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS
- H02P7/00—Arrangements for regulating or controlling the speed or torque of electric DC motors
- H02P7/06—Arrangements for regulating or controlling the speed or torque of electric DC motors for regulating or controlling an individual dc dynamo-electric motor by varying field or armature current
- H02P7/18—Arrangements for regulating or controlling the speed or torque of electric DC motors for regulating or controlling an individual dc dynamo-electric motor by varying field or armature current by master control with auxiliary power
- H02P7/24—Arrangements for regulating or controlling the speed or torque of electric DC motors for regulating or controlling an individual dc dynamo-electric motor by varying field or armature current by master control with auxiliary power using discharge tubes or semiconductor devices
- H02P7/28—Arrangements for regulating or controlling the speed or torque of electric DC motors for regulating or controlling an individual dc dynamo-electric motor by varying field or armature current by master control with auxiliary power using discharge tubes or semiconductor devices using semiconductor devices
- H02P7/285—Arrangements for regulating or controlling the speed or torque of electric DC motors for regulating or controlling an individual dc dynamo-electric motor by varying field or armature current by master control with auxiliary power using discharge tubes or semiconductor devices using semiconductor devices controlling armature supply only
- H02P7/29—Arrangements for regulating or controlling the speed or torque of electric DC motors for regulating or controlling an individual dc dynamo-electric motor by varying field or armature current by master control with auxiliary power using discharge tubes or semiconductor devices using semiconductor devices controlling armature supply only using pulse modulation
- H02P7/291—Arrangements for regulating or controlling the speed or torque of electric DC motors for regulating or controlling an individual dc dynamo-electric motor by varying field or armature current by master control with auxiliary power using discharge tubes or semiconductor devices using semiconductor devices controlling armature supply only using pulse modulation with on-off control between two set points, e.g. controlling by hysteresis
Landscapes
- Engineering & Computer Science (AREA)
- Power Engineering (AREA)
- Control Of Direct Current Motors (AREA)
Description
【発明の詳細な説明】
本発明は直流電動機の逆起電圧増幅回路に関し、特に電
動機の逆起電圧を利用した直流電動機の速度制御におい
て、その逆起電圧を増幅する回路に関する。DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a back electromotive voltage amplification circuit for a DC motor, and more particularly to a circuit for amplifying a back electromotive voltage in controlling the speed of a DC motor using the back electromotive force of the motor.
従来、電動機の逆起電圧を利用して直流電動機の速度制
御をする場合、直流電動機に並列に挿入したインピーダ
ンス回路（通常抵抗回路）により、電動機の逆起電圧を
分圧検出し、その値を直接位相制御回路にフィードバッ
クして電動機の主制御スイッチ（例えばサイリスタスイ
ッチ）の導通角を変えるという方式が採られている（特
開昭５０−１０４３６号参照）。Conventionally, when controlling the speed of a DC motor using the back electromotive voltage of the motor, the voltage of the motor's back electromotive force is detected as a divided voltage using an impedance circuit (usually a resistance circuit) inserted in parallel with the DC motor, and its value is calculated. A method has been adopted in which the conduction angle of the main control switch (for example, a thyristor switch) of the motor is changed by direct feedback to the phase control circuit (see Japanese Patent Laid-Open No. 10436/1983).
しかし、インピーダンス回路で得られる逆起電圧信号は
、電動機の回転数にほぼ比例して増減する信号であるた
め、この信号をそのまま位相制御回路に送つて、速度設
定信号と比較させるための測定信号ないしはフィードバ
ック信号として使用するという上述の方式には次のよう
な欠点がある。However, since the back electromotive voltage signal obtained by the impedance circuit is a signal that increases or decreases almost in proportion to the rotation speed of the motor, this signal is sent as it is to the phase control circuit and is used as a measurement signal for comparison with the speed setting signal. The above-mentioned method of using the signal as a feedback signal has the following drawbacks.
まず、低速時には、得られる逆起電圧信号が回転数に比
例して小さいため、この信号と設定速度信号とを比較し
てなされるところの半波ごとの主制御スイッチの導通期
間にずれが生じやすくなり、またこのようなずれの導通
期間に対する割合は、導通期間が大きいときのずれの占
める割合より大きくなりやすいため（すれ／導通期間（
小）＞ずれ／導通期間（大））、定速性（トルク）が著
・しく低下したり、ときには速度変動のために電動機に
騒音を生じさせたりする。First, at low speeds, the obtained back electromotive voltage signal is small in proportion to the rotation speed, so there is a difference in the conduction period of the main control switch for each half wave, which is determined by comparing this signal with the set speed signal. Also, the ratio of such deviation to the conduction period tends to be larger than the ratio of deviation when the conduction period is large (slipping/conduction period (
(small) > deviation/continuation period (large)), constant speed (torque) may be significantly reduced, and sometimes speed fluctuations may cause noise in the motor.
また高速時には逆起電圧信号が回転数に比例して大きく
なりすぎて速度制御が不能になるおそれがある。Furthermore, at high speeds, the back electromotive force signal becomes too large in proportion to the rotational speed, which may make speed control impossible.
この後者の欠点を補うため、前述の特開、昭５０−１０
４３６号ではツェナーダイオードを使用して電圧制限を
行なつているがツェナーダイオード方式では所定の入力
以上に対しては常に一定レベルに抑えられることになる
から必ずしも満足のいくものではない。そこで、本発明
は上述の欠点を除くため、検出した速度に比例する起電
圧信号を速度に反比例するような増倍率を以つて増幅す
る逆起電圧増幅回路を提供するとを目的とする。In order to compensate for this latter drawback, the above-mentioned Japanese Patent Application Publication No.
No. 436 uses a Zener diode to limit the voltage, but the Zener diode method is not always satisfactory because inputs exceeding a predetermined level are always suppressed to a constant level. SUMMARY OF THE INVENTION In order to eliminate the above-mentioned drawbacks, it is an object of the present invention to provide a back electromotive voltage amplification circuit that amplifies an electromotive voltage signal proportional to the detected speed with a multiplication factor inversely proportional to the speed.
本発明によれば、この目的は、逆起電圧検出用のインピ
ーダンス回路が半導体制御素子のバイアス回路を規定す
るように両者を接続するとともに、この半導体制御スイ
ッチの電源として電動機の主制御スイッチの０ＦＦ間に
おける整流電圧を使用し、この半導体制御素子の出力側
に逆起電圧の増幅された信号を与えるインピーダンス素
子を設けることにより達成される。According to the present invention, this purpose is to connect the impedance circuit for detecting the back electromotive voltage so as to define the bias circuit of the semiconductor control element, and to connect the 0FF of the main control switch of the motor as the power source of the semiconductor control switch. This is achieved by using a rectified voltage between the semiconductor control element and providing an impedance element that provides an amplified signal of the back electromotive voltage on the output side of the semiconductor control element.
位相制御の場合、主制御スイッチの導通期間と電動機の
印加電圧の平均値との間には比例関係があり、印加電圧
の平均値と電動機の回転速度との間には比例関係がある
から、うらをかえせば、主制御スイッチの非導通期間に
おける整流電圧と、電動機の回転速度（したがつてイン
ピーダンス回路により検出された逆起電圧）との間には
反比例関係がある。In the case of phase control, there is a proportional relationship between the conduction period of the main control switch and the average value of the voltage applied to the motor, and a proportional relationship between the average value of the applied voltage and the rotational speed of the motor. On the other hand, there is an inversely proportional relationship between the rectified voltage during the non-conducting period of the main control switch and the rotational speed of the motor (therefore, the back electromotive force detected by the impedance circuit).
したがつて検出した逆起電圧信号の小さい間は、半導体
制御素子のバイアスレベルは，小さい力吠きな整流電圧
の下で半導体制御素子は駆動されるため、かなり増幅し
た形の信号を出力側でとりだすことができる。他方検出
した逆起電圧信号の大きい場合は、半導体制御素子のバ
イアスレベルは大きいが小さな整流電圧の下で半導体制
御素子は駆動されるため出力側でとりだすことのできる
信号には限りがある。以上が本発明の原理である。Therefore, while the detected back electromotive force signal is small, the bias level of the semiconductor control element is driven under a small and strong rectified voltage, so a considerably amplified signal is output to the output side. You can take it out with . On the other hand, when the detected back electromotive voltage signal is large, the bias level of the semiconductor control element is large, but since the semiconductor control element is driven under a small rectified voltage, there is a limit to the signal that can be taken out on the output side. The above is the principle of the present invention.
以下、図面を参照して本発明の実施例を説明する。Embodiments of the present invention will be described below with reference to the drawings.
第１図に、本発明の実施例を含む回路が示されている。FIG. 1 shows a circuit including an embodiment of the invention.
１は商用交流電流で、ダイオードＤ４から成るブリッジ
整流回路にて全波整流された電源に変換される。２は電
動機の主制御スイッチであるトランジスタＴｒｌにて位
相制御される直流電動機である。1 is a commercial alternating current, which is converted into a full-wave rectified power source by a bridge rectifier circuit consisting of a diode D4. 2 is a DC motor whose phase is controlled by a transistor Trl which is a main control switch of the motor.
トランジスタＴ，ｌの導通信号は制御回路Ｃで与えられ
る。制御回路Ｃに与えられる測定情報は電動機２の逆起
電圧である。電動機２の逆起電圧は、電動機に並列に挿
入された抵抗Ｒ１とＲ２から成る分圧回路で検出される
。従来は、この検出値をそのまま、制御回路Ｃに送つて
いたのであるが、その欠点を除くため本実施例では下記
の構成の増幅回路が付加されている。A control circuit C provides conduction signals for transistors T and l. The measurement information given to the control circuit C is the back electromotive force of the motor 2. The back electromotive force of the motor 2 is detected by a voltage dividing circuit including resistors R1 and R2 inserted in parallel with the motor. Conventionally, this detected value was sent as is to the control circuit C, but in order to eliminate this drawback, an amplifier circuit having the following configuration is added in this embodiment.
すなわち、分圧回路の分圧点をＰＮＰトランジスタＴｒ
２のベースに接続し、トランジスタＴｒ２のエミッタを
電流制限抵抗Ｒ３を介して整流電圧のプラス側に、コレ
クターを抵抗Ｒ４を介して整流電圧のマイナス側に接続
したものである。In other words, the voltage dividing point of the voltage dividing circuit is connected to the PNP transistor Tr.
The emitter of the transistor Tr2 is connected to the plus side of the rectified voltage via a current limiting resistor R3, and the collector is connected to the minus side of the rectified voltage via a resistor R4.
抵抗Ｒ４に生じる電圧が制御回路に測定信号としてフィ
ードバックされる。以下、第２図を参照してこの増幅回
路の動作説明を行う。The voltage developed across resistor R4 is fed back to the control circuit as a measurement signal. The operation of this amplifier circuit will be explained below with reference to FIG.
図中、■１は整流回路の出力である整流電源電圧波形を
、Ｖ２は電動機２の両端の電圧波形を、Ｖ３は抵抗Ｒ４
の両端電圧を、■４は主制御トランジスタＴ，ｌの０Ｆ
Ｆ期間中増幅回路に加えられる整流電源電圧波形を、■
５は主制御トランジスタＴｒｌの入力信号波形を示す。
第２図の左半分Ａは電動機が低速モードにあるときの波
形であり右半分Ｂは電動機が高速モードにあるときの波
形である。さて、電動機が低速モードにあるときは、主
制御トランジスタＴｒｌは短かい０Ｎ期間Ｔ１と長い０
ＦＦ期間Ｔ２を有する。０ＦＦ期間Ｔ２中に、電動機に
は波形■２中に斜線で示すような小さな逆起電圧■２が
生じ、これが第１図の抵抗Ｒ１とＲ２から成る分圧回路
にて検出される。In the figure, ■1 is the rectified power supply voltage waveform that is the output of the rectifier circuit, V2 is the voltage waveform at both ends of the motor 2, and V3 is the resistor R4.
4 is the 0F voltage of the main control transistor T, l.
The rectified power supply voltage waveform applied to the amplifier circuit during period F is
5 shows the input signal waveform of the main control transistor Trl.
The left half A of FIG. 2 is a waveform when the motor is in low speed mode, and the right half B is a waveform when the motor is in high speed mode. Now, when the motor is in low speed mode, the main control transistor Trl has a short 0N period T1 and a long 0N period T1.
It has an FF period T2. During the 0FF period T2, a small back electromotive force (2) as shown by diagonal lines in the waveform (2) is generated in the motor, and this is detected by the voltage divider circuit consisting of resistors R1 and R2 in FIG.
抵抗Ｒ１に分圧された逆起電圧はトランジスタＴｌ。の
バイアス電圧となる。他方、この期間Ｔ２中にはかなり
大きな整流電源電圧■４が印加されている。したがつて
上述のバイアス電圧が比較的小さいにもかかわらず、か
なり増幅された電圧Ｖ３を抵抗Ｒ４に発生させることが
できる。なお、ＯＮ期間Ｔ１中に抵抗Ｒ４に電圧が生じ
ないようにするため、バイアス用のダイオードＤ５をト
ランジスタＴｒ２のコレクターと主制御トランジスタＴ
ｒｌ間に挿入している。次に、電動機が高速モードにあ
るときは、主制御トランジスタＴｒｌは長い０Ｎ期間Ｔ
「（したがつて電動機に印加される電圧は大きい）と短
かいＯＦＦ期間Ｔ２″とを有する。The back electromotive voltage divided by the resistor R1 is applied to the transistor Tl. The bias voltage will be . On the other hand, during this period T2, a fairly large rectified power supply voltage 4 is applied. Therefore, even though the bias voltage mentioned above is relatively small, a significantly amplified voltage V3 can be generated across the resistor R4. In addition, in order to prevent voltage from occurring in the resistor R4 during the ON period T1, a bias diode D5 is connected to the collector of the transistor Tr2 and the main control transistor T.
It is inserted between rl. Next, when the motor is in high speed mode, the main control transistor Trl is activated for a long 0N period T.
(therefore the voltage applied to the motor is large) and a short OFF period T2''.
０ＦＦ期間Ｔ２″中に、電動機の両端には斜線部で示す
ような大きな逆起電圧Ｖ２″が現われ、これが第１図の
分圧回路にて検出され、トランジスタＴｒ２に大きなバ
イアス電圧を与えトランジスタＴｒ９の導通を深めよう
とする。During the 0FF period T2'', a large back electromotive voltage V2'' appears at both ends of the motor as shown by the shaded area, and this is detected by the voltage divider circuit in FIG. Trying to deepen the continuity between the two.
しかし、トランジスタＴｒ２には波形■４の右半分に示
すように小さな整流電圧が印加されており、抵抗Ｒ４に
発生させることのできる電圧■３″には限界がある。な
んとなれば分圧回路Ｒ１の端子電圧と抵抗Ｒ４の端子電
圧との和が電源である整流電圧（そしてこれは、この場
合小さな値である）を超えることができないからである
。以上のことから、第１図に示す増幅回路は、低速時に
は、検出回路で得られた小さな起電圧信号を大きな整流
電源の下で比較的大きな倍率で増幅し、高速時には、検
出回路で得られた大きな起電圧信号を、小さな整流電源
の下で制限する作用を営み、電動機の０Ｎ期間Ｔ１中に
はダイオードＤ５によつて抵抗Ｒ４に電圧が生じないよ
うにする。However, a small rectified voltage is applied to the transistor Tr2 as shown in the right half of the waveform (4), and there is a limit to the voltage (3) that can be generated across the resistor R4. This is because the sum of the terminal voltage of R4 and the terminal voltage of resistor R4 cannot exceed the rectified voltage of the power supply (and this is a small value in this case).From the above, the amplification shown in FIG. At low speeds, the circuit amplifies the small electromotive voltage signal obtained by the detection circuit with a relatively large magnification using a large rectified power supply, and at high speeds, the large electromotive voltage signal obtained from the detection circuit is amplified by a small rectified power supply. During the ON period T1 of the motor, the diode D5 acts to limit the voltage at the resistor R4.
また、トランジスタＴ、２は分圧回路で検出された電圧
をバイアス電圧としているため、飽和状態で使用され、
Ｈｎあるいは温度変化の影響を受けず、素子選定が容易
であると共に精度の高い信号が供給できる。上記実施例
では、ブリッジ整流回路で全波整流した電源を使用して
いるが、半波整流した電源を使用することも可能である
。In addition, since the transistors T and 2 use the voltage detected by the voltage dividing circuit as the bias voltage, they are used in a saturated state,
It is not affected by Hn or temperature changes, allows easy element selection, and can provide highly accurate signals. In the above embodiment, a full-wave rectified power source is used in the bridge rectifier circuit, but it is also possible to use a half-wave rectified power source.
また増幅用のトランジスタとしてＰＮＰ形トランジスタ
を例示したが、ＮＰＮ形のトランジスタでも構成できる
。主制御−スイッチとしては例示のトランジスタスイッ
チの外にサイリスタ等のスイッチが使用できることはも
ちろんである。このように本発明によれば、電動機の逆
起電圧を、該電動機の０ＦＦ期間中の整流電源電圧の下
で増幅させることにより、１低速時での定速性（トルク
）が上げられ安定した制御がなされる。Further, although a PNP type transistor is illustrated as an example of an amplification transistor, an NPN type transistor may also be used. As the main control switch, it is of course possible to use a switch such as a thyristor in addition to the illustrated transistor switch. As described above, according to the present invention, by amplifying the back electromotive voltage of the motor under the rectified power supply voltage during the 0FF period of the motor, the constant speed (torque) at low speed is improved and stabilized. Control is exercised.
２高速での速度制御が容易になる。2. Speed control at high speed becomes easy.
３特に、逆起電圧の小さいタイプの直流電動機の定速性
（トルク）が上げられる。3. In particular, the constant speed (torque) of a type of DC motor with a small back electromotive force can be improved.
等の効果がある。There are other effects.
さらに、増幅回路の電源は、電動機に印加されない部分
を使用するものであるから、共通の電源ラインを使用す
ることができ構成が簡単になる。本発明はミシン、巻上
機、巻取機、バルク開閉器等で使用される直流電動機の
速度制御において特に有効な逆起電圧増幅回路である。Furthermore, since the power supply for the amplifier circuit uses a part that is not applied to the motor, a common power supply line can be used, which simplifies the configuration. The present invention is a back electromotive voltage amplification circuit that is particularly effective in controlling the speed of DC motors used in sewing machines, hoisting machines, winding machines, bulk switches, and the like.
第１図は、本発明の実施例である逆起電圧増幅回路を付
加した直流電動機の速度制御回路図、第２図は、低速時
と高速時における第１図の各部の波形図である。
Ｒｌ，Ｒ２・・・分圧回路、Ｔ，２・・・増幅用トラン
ジスタ、Ｒ４・・・増幅逆起電圧発生用抵抗、Ｖ４・・
・増幅回路印加整流電圧波形。FIG. 1 is a speed control circuit diagram of a DC motor to which a back electromotive voltage amplification circuit is added according to an embodiment of the present invention, and FIG. 2 is a waveform diagram of each part of FIG. 1 at low speed and high speed. Rl, R2... Voltage dividing circuit, T, 2... Amplifying transistor, R4... Resistor for amplifying back electromotive voltage generation, V4...
- Rectified voltage waveform applied to the amplifier circuit.
Claims (1)
度制御を行う回路において、前記直流電動機の逆起電圧
を検出する該電動機に並列に挿入した第１、第２の抵抗
からなる分圧回路を有し、整流回路の正側出力に第３の
抵抗を介してトランジスタのエミッタを接続すると共に
該トランジスタのベースに前記分圧回路の分圧点を接続
してエミッタ、ベース間にバイアスが与えられるように
し、前記第２の抵抗と電動機の負側との接続点と前記ト
ランジスタのコレクタとの間にバイパス用のダイオード
を接続し、前記トランジスタのコレクタ側に第４の抵抗
を接続し、この第４の抵抗の他端と前記トランジスタの
エミッタ間に前記主制御スイッチの非導通期間における
整流電圧のみが印加されるようにしたことを特徴とする
直流電動機の逆起電圧増幅回路。1. In a circuit that controls the speed of a DC motor by changing the conduction period of a main control switch, a voltage divider circuit consisting of a first and second resistor inserted in parallel with the motor detects the back electromotive force of the DC motor. The emitter of the transistor is connected to the positive output of the rectifier circuit via a third resistor, and the voltage dividing point of the voltage dividing circuit is connected to the base of the transistor, so that a bias is applied between the emitter and the base. A bypass diode is connected between the connection point between the second resistor and the negative side of the motor and the collector of the transistor, a fourth resistor is connected to the collector side of the transistor, and the fourth resistor is connected to the collector of the transistor. 4. A back electromotive voltage amplification circuit for a DC motor, wherein only a rectified voltage during a non-conducting period of the main control switch is applied between the other end of the resistor No. 4 and the emitter of the transistor.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP54136664A JPS6042707B2 (en) | 1979-10-23 | 1979-10-23 | Back electromotive voltage amplification circuit for DC motor |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP54136664A JPS6042707B2 (en) | 1979-10-23 | 1979-10-23 | Back electromotive voltage amplification circuit for DC motor |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS5662082A JPS5662082A (en) | 1981-05-27 |
| JPS6042707B2 true JPS6042707B2 (en) | 1985-09-24 |
Family
ID=15180603
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP54136664A Expired JPS6042707B2 (en) | 1979-10-23 | 1979-10-23 | Back electromotive voltage amplification circuit for DC motor |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS6042707B2 (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH03143008A (en) * | 1989-10-27 | 1991-06-18 | Mitsubishi Electric Corp | Noise filter |
-
1979
- 1979-10-23 JP JP54136664A patent/JPS6042707B2/en not_active Expired
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH03143008A (en) * | 1989-10-27 | 1991-06-18 | Mitsubishi Electric Corp | Noise filter |
Also Published As
| Publication number | Publication date |
|---|---|
| JPS5662082A (en) | 1981-05-27 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| US4449081A (en) | Compensating outputs of hall generators to minimize effects of temperature variation and the like | |
| US4427931A (en) | Speed control apparatus for direct current motor | |
| US5287044A (en) | Drive circuit for brushless motor | |
| US4638223A (en) | Motor driving circuit | |
| JPS6042707B2 (en) | Back electromotive voltage amplification circuit for DC motor | |
| JPS6098822A (en) | Overheat detector of electromagnetic mechanism | |
| US3219900A (en) | Direct current motor control systems | |
| US4737696A (en) | Actuator drive circuit | |
| US5416390A (en) | Circuit for driving a loading motor of a video cassette tape recorder | |
| JP3333318B2 (en) | Output transistor saturation prevention circuit | |
| JPH0832196B2 (en) | Driving circuit for stepping motor | |
| JP4136134B2 (en) | DC power supply circuit | |
| JPS6110477Y2 (en) | ||
| JPS6217957B2 (en) | ||
| JPS6031436Y2 (en) | AC motor control circuit | |
| JPH0640479Y2 (en) | Current detection circuit | |
| JPS6133483B2 (en) | ||
| JP2935367B2 (en) | Motor torque limit control circuit | |
| JPH0733595Y2 (en) | Brushless motor induced voltage detection circuit | |
| US3529225A (en) | Motor speed controls | |
| JPH058799Y2 (en) | ||
| JPH0753297Y2 (en) | Differential amplifier circuit | |
| JPH0724807Y2 (en) | DC amplifier circuit | |
| JPS63148886A (en) | Motor driver | |
| JPS5929373Y2 (en) | power detection circuit |