JP3020400B2 - Drive voltage control circuit for DC motor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus using a DC motor, which controls the number of revolutions of the DC motor. The present invention relates to a drive voltage control circuit of a DC motor for performing adjustment and the like.

[0002]

2. Description of the Related Art Generally, the control of the number of revolutions of a DC motor 21 has a circuit configuration including a power supply circuit 10, a motor unit 11, and a microcomputer 12, as shown in the block diagram of FIG. The power supply circuit 10 rectifies and smoothes an AC voltage input to a power supply input terminal 13 by a rectification circuit 14 and a smoothing circuit 15.
I do. On the other hand, the auxiliary power supply unit 1 is used for powering various circuits.
6, a constant voltage (for example, 5 V) is obtained and supplied from the fixed voltage output terminal 36 to the Vcc supply unit 19 ;
A voltage of about 0 to 50 V is obtained by the variable power supply unit 17 for the motor power supply, and the DC motor 2 is supplied via the motor driver 20.
1 is supplied with a drive voltage.

[0003] The number of rotations of the DC motor 21 is detected by a Hall element 22 , and a rotation logic 23 and a pulse generator 2 are provided.
4, the rotation number pulse is output as a rotation number pulse. The rotation number pulse is received by the microcomputer 12 via the pulse signal output terminal 38, and the microcomputer 12 converts the digital signal into an analog signal by D / A conversion. The control signal is input to the voltage control circuit 18 to control the rotation speed of the DC motor 21.

[0004] In the drive voltage control circuit for a DC motor as described above, the conventional power supply circuit 10, it has been a circuit configuration as shown in FIG. That is, the power input terminal 1
3 is rectified by the rectifier circuit 14 and the smoothing circuit 15
After smoothing, high-frequency switching by the switch element 32, you output from the variable voltage output terminal 37 through the transformer 34.

[0005] Then, D / A conversion is performed from the motor unit 11 via the microcomputer 12 and the analog signal is input to the control signal input terminal 39.
The analog signal is output to the output voltage control circuit 1
8, the control voltage and the slope of the output voltage are set in the first operational amplifier 25, and the output voltage is set in the second operational amplifier 26. A feedback signal is sent by a photocoupler 31 composed of a phototransistor 30, and an on / off pulse width of a switch element 32 is controlled by a pulse width control IC 33 to automatically and continuously vary an output voltage. In addition,
The transistors 27 and 28 and their peripheral circuits limit the maximum output voltage of the power supply circuit 10.

[0006]

[Problems that the Invention is to Solve In the conventional power circuit 10, the inside as the output voltage control circuit 18 1
Of the operational amplifier 25 and the second operational amplifier 26,
As shown in FIG. 3, the output voltage can be accurately controlled by the high amplification factor. However, the first operational amplifier 25, in addition to the second operational amplifier 2 6, in the variable power supply section 17, and requires operational amplifier auxiliary supply circuit 35 for output voltage control circuit 18, also amplified adjustment of the rate also必
In other words, since many peripheral components and circuits are used in addition to the first operational amplifier 25, the second operational amplifier 26, the operational amplifier auxiliary power supply circuit 35, and the like, the number of components is large.
For this reason , there is a problem that the cost of the circuit increases.

An object of the present invention is to obtain a circuit in which the circuit cost is reduced as much as possible while keeping the accuracy substantially the same as the conventional one, since the rotation speed control device of the DC motor 21 is often used in household electric appliances. Things.

[0008]

According to the present invention, there is provided a power supply circuit comprising:
Supplies a DC voltage to the DC motor 21 and sends a control signal for controlling the rotation speed of the DC motor 21 to the power supply circuit 10.
Of the DC motor input to the output voltage control circuit 18
In the dynamic voltage control circuit , the output voltage control circuit
As a reference voltage source which determines the output voltage of the power supply circuit 10, constituted by connecting a control circuit 47 mainly composed of transistors 42, a transistor 42 of the control circuit 47, before
Return from the DC motor 21 via the control signal input terminal 39
Kaesa is continuously controlled based on the control signal input, the control
By changing the reference voltage by the control circuit 47,
A DC motor drive voltage control circuit characterized in that the output voltage of the force voltage control circuit 18 is continuously varied to control the rotation speed of the DC motor 21.

[0009]

[Operation] The microcomputer 12 transmits the rotation speed pulse of the DC motor 21 to the microcomputer 12.
The microcomputer 12 converts the analog signal into an analog signal, and then inputs the analog signal to a control signal input terminal 39 of the power supply circuit 10 as a control signal. Here, the transistor 42 is mainly used in parallel with the reference voltage source that determines the output voltage of the power supply circuit 10.
By the control circuit 47 connected to the microcomputer 12
Assuming that the control signal input to the control signal input terminal 39 changes linearly, the resistors 44 and 4 of the control circuit 47
5, the voltage is applied to the transistor 42 and the power supply circuit
The voltage source that determines the output voltage of the power supply circuit 10 changes linearly despite the presence of the reference voltage source.
Also linearly continuously variable output voltage. Therefore, the delicate rotation speed control of the DC motor 21 is continuously variable with an accuracy comparable to the conventional one, and the air volume is controlled by the air conditioner, the temperature of the hot water by the water heater, the water flow by the washing machine, and the exhaust volume by the ventilation fan. You.

[0010]

An embodiment of the present invention will be described below with reference to the drawings. In FIG. 1, the rectifier circuit 14, the smoothing circuit 15, and the auxiliary power supply unit 16 are the same as the conventional circuit. In the present invention, the output voltage control circuit 18 includes the power supply circuit 1.
As a voltage source serving as a reference voltage for determining an output voltage of 0 ,
A control circuit 47 having a control signal input terminal 39 is connected.

The control circuit 47 connects the cathode and the anode of a Zener diode 40 for limiting the maximum value of the output voltage of the power supply circuit 10 to the emitter and the collector of the transistor 42. between the positive terminal of the control signal input terminal 39, connect one of the voltage dividing resistors 44 based <br/> resistor 43 in series, the base
Over scan resistor 43 and one resistor divider 44 connection point between the control signal input terminal 39 - between the terminal and the other dividing resistors 4
5 and a capacitor 46 are connected in parallel with each other. In this circuit, the voltage dividing resistors 44 and 45
It divides the control voltage.
Are inserted in order to remove noise mixed into the control voltage. A transistor 41 is provided between the light emitting diode 29 and the voltage source zener diode 40.
Is inserted.

In the above configuration, the AC input of the power input terminal 13 is rectified by the rectifier circuit 14 and the smoothing circuit 15.
And, after smoothing, and high-frequency switching by the switch element 32, a variable voltage output terminal 3 through the transformer 34
7 and supplied to the DC motor 21 via the motor driver 20 of the motor unit 11. At the same time, a constant voltage (for example, 5 V) obtained by the auxiliary power supply unit 16 is sent from the fixed voltage output terminal 36 to the Vcc supply unit 19, and is supplied to the Vcc terminal of each circuit . The rotation speed of the DC motor 21 is detected by a Hall element 22 , output as a rotation speed pulse by a rotation logic 23 and a pulse generator 24, and the rotation speed pulse is received by the microcomputer 12.
After D / A conversion of the digital signal into an analog signal, the digital signal is input to the control signal input terminal 39 of the power supply circuit 10 as a control signal.

A control circuit 47 mainly including a transistor 42 is connected in parallel with the power supply circuit 10.
When that control signal input from the microcomputer 12 to the control signal input terminal 39 is turn into linearly varying voltage dividing resistors of the control circuit 47 4
4 and divided by Ru is applied to the transistor 42 at 45.
As long as the voltage source that determines the output voltage of the power supply circuit 10 is equal to or lower than the set voltage of the Zener diode 40, the output voltage changes linearly, and the output voltage of the power supply circuit 10 also continuously changes linearly as shown in FIG. Therefore, the delicate rotation speed control of the DC motor 21 is continuously varied with moderate accuracy, and the air volume is controlled by the air conditioner, the temperature of the hot water by the water heater, the water flow by the washing machine, and the exhaust volume by the ventilation fan. When the output voltage of the power supply circuit 10 exceeds the maximum value set for safety, the Zener diode 40 turns on to limit the output above the maximum value.

[0014]

(1) According to the present invention, the DC motor 21
The subtle rotational speed control can be continuously varied with moderate accuracy, so that the air volume can be controlled by an air conditioner, the temperature of hot water by a water heater, the water flow by a washing machine, and the exhaust volume by a ventilation fan.

(2) Since a simple circuit configuration can be obtained, a low-cost and highly reliable drive voltage control circuit for a DC motor can be provided.

[Brief description of the drawings]

FIG. 1 is an electric circuit diagram showing an embodiment of a drive voltage control circuit for a DC motor according to the present invention.

FIG. 2 is an output characteristic diagram according to the circuit of the present invention.

FIG. 3 is an output characteristic diagram of a conventional circuit.

FIG. 4 is a block diagram of a drive voltage control circuit of a general DC motor.

FIG. 5 is an electric circuit diagram showing a conventional drive voltage control circuit for a DC motor.

[Explanation of symbols]

10 power supply circuit, 11 motor part, 12 microcomputer, 1
3 ... power input terminal, 14 ... rectifier circuit, 15 ... smoothing circuit,
Reference numeral 16: auxiliary power supply unit, 17: variable power supply unit, 18: output voltage control circuit, 19: Vcc supply unit, 20: motor driver, 21: DC motor, 22: hall element, 23: rotation logic, 24: pulse generator , 25: first operational amplifier, 26: second operational amplifier, 27: transistor, 2
8 ... transistor, 29 ... light emitting diode, 30 ... phototransistor, 31 ... photocoupler, 32 ... switch element, 33 ... IC for pulse width control, 34 ... transformer, 35
... Auxiliary power supply circuit for operational amplifier, 36 ... Fixed voltage output terminal, 37 ... Variable voltage output terminal, 38 ... Pulse signal output terminal, 39 ... Control signal input terminal, 40 ... Zener diode, 41 ... Transistor, 42 ... Transistor, 43 …
Resistance, 44: resistance, 45: resistance, 46: capacitor, 4
7 ... Control circuit.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) H02P 5/00-5/26 H02P 7/00, 7/36 H02M 3/28

Claims (4)

(57) [Claims] A DC voltage is supplied from a power supply circuit to a DC motor, and a control signal for controlling the rotation speed of the DC motor is input to an output voltage control circuit of the power supply circuit . In the drive voltage control circuit ,
The output voltage control circuit 18, as a reference voltage source which determines the output voltage of the power supply circuit 10, constituted by connecting a control circuit 47 mainly composed of transistors 42, the control circuit 47
Of the transistor 42, continuous control is based on the control signal inputted the direct current motor 21 is fed back via the control signal input terminal 39, a reference voltage by the control circuit 47
A drive voltage control circuit for a DC motor, wherein the output voltage of the output voltage control circuit 18 is continuously varied to control the rotation speed of the DC motor 21. 2. A control circuit 47 for determining an output voltage of the power supply circuit 10 has a control signal input terminal 39 connected to a transistor 42.
2. A DC terminal according to claim 1, wherein a series resistor 43, a voltage dividing resistor 44 and a resistor 45 are inserted between the base of the transistor 42 and the control signal input terminal 39. Motor drive voltage control circuit. 3. The transistor 42 in the control circuit 47.
A Zener diode 40 for limiting the maximum value of the output voltage of the power supply circuit 10 is connected between the collector and the emitter of the power supply circuit 10 with its anode connected to the collector of the transistor 42 and its emitter connected to the cathode of the transistor 42 in parallel. The drive voltage control circuit for a DC motor according to claim 1 or 2, wherein: 4. The power supply circuit 10 for controlling the rotation speed of the DC motor 21 is used for controlling the rotation speed of the DC motor 21 in home electric appliances such as an air conditioner, a water heater, a washing machine, and a ventilation fan. 4. A drive voltage control circuit for a DC motor according to claim 2 or 3.