JPS6055876A - Speed control circuit of dc motor - Google Patents

Abstract

PURPOSE:To enable to control a speed in a wide range by constructing a Wheatstone bridge circuit with an internal resistance of a DC motor as an element, and feeding back the output to a motor drive circuit. CONSTITUTION:When a control voltage is applied to an input terminal 11 of a normal rotation circuit 3, an operational amplifier 18 outputs a current in response to the output of a control voltage amplifier A. Thus, a current is supplied to a DC motor 1. At this time, a Wheatstone bridge circuit B is composed of the internal resistance 1', resistors 25, 26a, 26b of the motor 1, and the unequilibrated output voltage of the circuit B is fed back through an amplifier F to the operational amplifier 18 of a power amplifier W. Thus, a speed can be controlled in a wide range, and, even if a load of the motor varies, the constant rotating speed can be maintained.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a speed control circuit for a DC motor, particularly a small IC1, a current motor.

When controlling the speed of a DC motor, the simplest method is to use a voltage feedback method that detects the electromotive force generated by one rotation of the motor. Since this system can be used even if the motor is not a special one, it is called an electronic power vaner motor and is often used in small tape recorders and record players.

In order to perform speed control with higher precision, a rotation detection method using a tacho generator is adopted. l\(
If the speed control is performed using the tach generator, the stability will be significantly improved, and if the speed is controlled by the tach generator, the stability will be much more accurate. All will be bribed.

However, although the former voltage feedback force type is suitable for speed control in a narrow range, it is not suitable for speed control over a wide range. In addition, the latter Tough Noenererator method requires not only the Tough Generator itself, but also requires a certain amount of amplifier system, which has a cost bar of 70m, and also has a compact (compatible with the There is a drawback that it does not.

Therefore, the present invention has high performance, is suitable for compact equipment, and can control all speeds over a wide range from low rotational speeds to high rotational speeds. One object of the present invention is to provide a speed control circuit for a DC motor that maintains the rotational speed.

For this reason, the present invention includes a control amplifier circuit that amplifies a control signal for controlling the speed of a DC motor, and a power amplifier circuit that increases the output of this control signal amplifier circuit to the driving voltage of the DC motor. DC motor speed control circuit 1
At this point, a Wheatstone Pritzno circuit is provided to reduce the internal resistance of the iQ-style motor, and
Detect the change in motor current in the wheel 1 motor current circuit and convert it to voltage.
．． The basic feature is that the i-circuit is provided with a feedback circuit that suppresses negative feedback.

Preferably, the feedback circuit (1) is provided with an amplifier for amplifying the change in motor current, thereby increasing the ability of the Wheatstone Pritzno circuit to detect a current imbalance.

Hereinafter, the present invention will be specifically explained with reference to embodiments shown in the accompanying drawings.

FIG. 1 is a circuit diagram of an embodiment, showing speed control circuits in both forward and reverse directions. In the figure, 1 is a small DC motor, and the entire circuit is composed of a reverse rotation circuit 2, a forward rotation circuit: (), and a reverse rotation circuit 2, a forward rotation circuit 3, and a motor 1. In February, the power supply line from the common 10V power supply...[.

5.6 is set to fF and a voltage of 10\pa is supplied. 10\"An electrolytic capacitor °i for absorbing voltage fluctuations is connected to the power supply, and a noise capacitor 8 is connected to the power supply line 4, and a power supply line 5t is connected to the power supply line 4. 11) is connected.Then, the reversing circuit 2
Both the forward rotation circuit 3 and the forward rotation circuit 3 are grounded to the ground line 10 of the

In the forward rotation circuit 3, 11 is direct during forward rotation; rough motor 1
A control voltage input terminal r- inputs a voltage signal for controlling the rotation speed of the motor, and an input terminal j-11 is connected to a control signal amplification circuit for amplifying the control signal.

The output part of the amplifier circuit l\ is connected to the human power part of the power amplifier circuit W, which increases the voltage that can continuously drive the DC motor 1. The output section of the power amplifier circuit W is connected to a Wheatstone bridge 1, which includes a DC motor 1 and has an internal resistance of the motor 1 as one of the connecting elements. The two output ends of the circuit 13 are connected to the amplifier circuit 1.
The output portions of the amplifier circuits 1 and 1 are connected to the power distribution amplifier circuit W.

The control signal amplification circuit A includes a 1iif < door 117 amplifier 12 (hereinafter referred to as an "operational amplifier" 1 operational amplifier I), and the human power NIr-1] is inputted via a resistor 13 to 1. The inverting input of the operational amplifier 12 connected to the non-inverting input of the operational amplifier 12 is grounded via a resistor 1.1.

Between the inverting input of the operational amplifier 12 and the output of the operational amplifier 12, a fixed resistor 15 and a series of 16 IIf variable resistance resistors are connected, forming a non-inverting amplifier circuit. For example, the resistance value of the resistor 14 is 1 (Ω), that of the fixed resistor 15 is 10Ω, and the resistance value of the variable resistance resistor 1 is 2SK.
Ω so that the gain can be freely varied between 2 and 4.5. Furthermore, the input terminal 11 is grounded via a resistor 17 (approximately looKΩ), which has a relatively large resistance value. .

The power amplification circuit W is based on the single force of the operational amplifier l3 and a group of power transistors connected in a Britno type, that is, Nl'
N-type transistor 1! ] and r' N r' type transistor 2 (), and the output of the operational amplifier 12 is connected to the resistor 2.
1 to the non-inverting input of the operational amplifier 18, while the inverting input of the operational amplifier 18 is connected to ground through the resistor 22. The output of the operational amplifier 1) is connected to the bases of the power transistors 20 and 20, and the resistor 2
3 and is connected to the ground line 10. NI'
The collector of the N-type transistor 15) is connected to the feed line [1, and the emitters of the N-type 1 transistor 19 and the I'NI' transistor 2 () are connected in common, and the collector of the latter transistor 20 is grounded′
There is C. The current for driving the motor 1 is supplied from the connection point 2.1 of the emitters of the power transistor group. Connection point 2
・1 resistor 25 connected at one end to 1, 1 rimmer resistor 2G connected between connection point 24 and ground line 10, and 1
- It consists of an internal resistance (indicated by 1゛) of the DC motor 1, which has the J end 27 connected to the small end of the resistor 25. resistance 2
! The resistance of 3 (for example, about 1 Ω on 11′lI, and the resistance value of the trimmer resistor 26 is 2f in this example) is selected to be 3 KΩ.
, Note that 1r1. Ikegata input terminal 28 of flow motor 1 is resistor 1
Power tractor/transistor II in reversing circuit 2 via 2j3! J, +2+1 is connected to the eminter nucleus concatenation point 124.

A diode 2 connected between the end of the resistor 25 and the power supply line 6! ] and the power connected between the end of the resistor 25 and the ground. Diode 2 inserted between the collector and emitter of J, 2f)! I, :((l is the latter to protect each of the inductive loads j=IL power transformer l!1, 211.

The trimmer resistor 26 is divided by its contact 31 into 2-] resistors 26a, 261), the box end (opposite side) of the dividing resistor 2til+ is connected to the earth line 1(), and one end (opposite side) of the dividing resistor 2f3a The contact side) is connected to the emitter connection point 24, that is, one end of the resistor 25. The contacts of the trimmer resistor 26 (1 constitutes the output part of m- of this Wheatstone Pritzno circuit B), and the contacts of the resistor 25 constitute another output part.

The amplification amount IJf (1.゛ is an operational amplifier;
The terminals 21 and 1 of 6 are connected.The non-inverting input is connected to the resistor 25 by connecting the resistors 1 and 4.

A fixed resistor (5) and an iI variable resistor 3G series connection are connected between the non-inverting input and output of the operational amplifier (2), as well as a capacitor 37. The output of the operational amplifier 32 and the operational amplifier 1; Resistance between non-anti-QIi people and forces:
(8 is connected. This resistor: (); Between the opposite output side (inverting input l1tll of the operational amplifier 18) and the emitter connection point 24, there is a resistor with a relatively large resistance value (about in<Ω): (9 is connected. -Resistance written in: j: (, 3r
The resistance value of the fixed resistor 35 is set to +OKΩ, and the resistance value of the variable resistance i+J is set to about 200 KΩ. In addition, operational amplifier 3
A diode connected between the two inputs of 2 and 4. (1, /1. + is for protection against excessive force.

Further, the cathode of the diode 40 is connected to the earth line 10 via a resistor . . . 12 having a relatively large resistance value (about IKΩ).

Forward diversion circuit: (Although it is depleted as in the handbook, reverse ++ configured λ・j symmetrically. The reference number (, l (, 1 + 1 series) is 1
・The explanation of its configuration is omitted.3 Next, we will explain the circuit operation.
When \'IIX) is applied to the input terminal 11, it is amplified to a voltage by the illumination j1 amplifier circuit 7\ (gain G), and is input to the non-inverting input of the operational amplifier after passing through the resistor 21. The operational amplifier 1) outputs a current 1ν (on the order of mA) corresponding to ＼゛ to the power transistor j1, and the power transnoster 1! ), add 1 node to the base of 1, and trifle the power 1 runnostar 11 nodes (current increaser: β). An incoming current β·1ν flows from the power supply line 6 through the path of the power transnoster 10, the connection point 2/1, and the resistor 25, 1t1
The current motor 1 rotates at a rotational speed proportional to this current β·1v. At this time, the value 1111 of Figure 2 C and Wheatstone Buri 7 shown in Figure 3 is maintained.Here, if the negative 111i of motor 1 is increased, the rotational speed tends to decrease. Figure 2 shows the internal resistance 1 of the
The current flowing through j decreases, and the balance of the Voightstone fringe rotation y4 and 3 collapses.

This imbalance is caused by the operation 7+y in the amplifier circuit 1.
The current flowing into the inverting input is decreased and the current flowing into the inverting input is increased. The operational amplifier 32, which forms the inverting booster 111 sub-01 circuit (13), converts this current change into a voltage j14 and outputs a voltage higher than the voltage at balance. This feedback voltage is generated by the resistor 38. A negative feed signal of 1 is applied to the inverting input of the operational amplifier 1 of the power amplifier circuit \~'. Operational amplifier 1) Output type of 3; Thread is the amount corresponding to the increase in feed bite (j Increase the fire.

The power transistor 1 acts so as to cause more current to flow than the current that flowed during the closing of step 11.i.

As a result, the current flowing through the motor 1 (internal resistance B) is compensated for the decrease in rotational speed due to the increase in motor load, and maintains a constant rotational speed.

Conversely, if the load on the motor 1 decreases, the rotational speed will increase, but the current flowing through the internal resistor B will increase, causing the balance of the Wheatstone horn 13 to collapse, and the output of the operational amplifier 32 will decrease.・It is lower than the F11 hour train by the amount commensurate with the loss of balance.

The output of the motor drive amplifier 18 decreases due to this feed current (i-). The motor drive current is reduced by a corresponding amount, and the motor 1 rotates to maintain a constant rotational speed. In the past, the amplifier circuit 1 and 2 detected changes in the motor current flowing through the Wheatstone bridge circuit, converted it to voltage, and gave negative feedback to the voltage amplifier circuit W (J's feed puncture). This feedback circuit uses a simple resistor and an operational amplifier (2), so the detection ability to detect changes in the motor voltage is high, and the Control of Kankou 1.1 is very good.

Moreover, as shown in FIG. 1, an operational amplifier +2. Since Iji may be a straight line 1'1, regardless of the magnitude of the control voltage \",
The rotational speed of the DC motor 1 changes in proportion to the control claw, so that the speed of the ICfC upstream motor 1 can be controlled over a range from low rotational speed t'Ji degrees to high rotational speed.

Furthermore, when stopping the motor 1, the control il+1 input terminal 11 is set to zero voltage, but the jl and electromotive force of the motor 1 are greatly amplified via the feedback circuit F, and therefore the power amplifier circuit W responds promptly, and the supply of motor current is stopped 11- instantaneously. That is, since the rotation stop 1- is performed by a circuit configuration based on a dynamic brake, there is an advantage that the time between 7 and 11, ν during high-speed rotation can be shortened.

The operation of the 10 wide-purpose circuit 3 in item 1 is based on the reversing circuit 2t'.
are exactly the same l and η, and the reverse control control 1. A voltage of 0 or 11 (voltage) is applied to the W input terminal r111.

The circuit of the embodiment (Fig. 1) connects the DC motor to 11[・reverse V
, to perform a predetermined operation (for example, forward/reverse tape feeding operation)
It can be applied to all devices that execute microfilm league equipment (4Q Mj P: installation), and more particularly to the electrophotographic microfilm disclosed in Japanese Patent Application No. 57-(131) B4G6 (IT). b) A camera that uses
League-use microfil 1. It is preferable to apply it to the apparatus, in which case image access is easy to perform, and the film stopping position 16 accuracy can be greatly improved.

Although the embodiment shown in FIG. 1 combines the forward rotation circuit 3 and the reverse rotation circuit 62 for the DC motor indicated by -', as can be seen from the explanation in the book, there are This is one circuit to achieve the purpose of the term.
f! If you are only 1 year old, you should stay at 1 and stay at C.

As described above, the present invention 1; I:l/1. By using the internal resistance of the current motor as an element, a Boyet Stone 7 ring circuit is set up, which detects changes in the motor current applied to the Boyet Stone Bringe circuit, converts it to voltage, and applies a negative voltage to the motor drive circuit. Control the motor rotation speed by applying feedback! ++ j, because I did it, @-1
The servo system has a unique configuration that provides four-degree control over a wide range from low to high rotational speeds, and is effective in maintaining a constant rotational speed even when the motor load fluctuates. be done.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram of an embodiment of the present invention, and FIG. 2 is a circuit diagram illustrating the main parts of the circuit shown in FIG. 1... Small Jf1 DC motor, 1.1.1. I+・
Control 611 Input terminal r of f7τ, A... Control signal amplifier circuit, ~'... Power amplifier circuit, 11... Wheatstone bridge circuit, F"... Feedback amplifier circuit,
12HIL 32... operational amplifier.

Claims (2)

[Claims] (1) Includes a control signal amplification circuit that amplifies the control signal 1 for controlling the speed of the DC motor, and a power amplification circuit that increases the output of this control signal amplification circuit to the driving voltage of the DC motor specified in -1- In the speed control circuit of a DC motor, -
11. A Wheatstone circuit is provided to reduce the internal resistance of the DC motor as an element, and the
A feedback circuit is provided to detect a change in the motor current in the stone bridge circuit, convert it to voltage, and apply negative feedback to the power amplifier circuit described in -1.
A speed control circuit for an iCfC upstream converter with - and as 1 and te signs. (2) The feedback circuit has a built-in amplifier that amplifies changes in the motor voltage (1) AC.
Speed control of 11r flow motor described in range of requirements (1) 91
1 circuit.