JP3086431U - Control device for heat dissipation system - Google Patents

Abstract

(57) [Summary] To provide a control device for a heat dissipation system. The control circuit of the heat dissipation system of the present invention uses an output signal from an external device electrically connected to the heat dissipation system to control the voltage supply of the heat dissipation system.
Prevents being disturbed by PWM signal. The control unit is electrically connected between the heat dissipation system and a power supply for supplying voltage to the heat dissipation system, and generates a control signal to switch the power supply on and off. A voltage regulator, which is electrically connected to the signal generator and is provided in parallel with the signal generator and continuously supplies the basic voltage to the heat dissipation system. Prevent interference.

Description

[Detailed description of the invention]

[0001]

[Technical field to which the invention belongs]

 The present invention relates to a control circuit for a heat dissipation system, and particularly to a pulse width modulation (PWM) control circuit for a DC fan.

[0002]

[Prior art]

 FIG. 1 is a diagram showing a known circuit for controlling the rotation speed of a fan 11 using a transistor 12 such as a switch, and whether or not a voltage supply Vcc of a DC fan is turned on is determined by a pulse width modulation signal. Directly controlled, the fan changes the rotation speed. However, the design of such a circuit directly controls the voltage supply Vcc, and the signals output by the frequency generator (FG) and the rotational speed measuring device (RD), both electrically connected to the fan, Blocked by signal.

FIG. 2 shows that, under normal conditions, the FG signal of the fan rotation speed has a waveform as shown in FIG. And the actual rotation speed of the fan is not measured correctly.

Similarly, as shown in FIG. 3, the RD signal for measuring the rotation speed of the fan has a low potential under normal conditions (indicated by (1)), and only under abnormal conditions. Change to high potential. However, when the voltage supply of the fan is directly controlled by the PWM signal, the RD signal has a waveform (3) even under a normal state due to the disturbance of the PWM signal. Either the FG signal or the RD output signal is disturbed by the PWM signal, and the actual rotational speed of the fan cannot be measured accurately.

Further, the switching interval of the transistor 12 changes according to the change in the duty cycle of the PWM signal, and controls the average current supplied to the fan 11. However, when driving the fan, the duty cycle of the PWM signal input to the transistor must be limited to a certain range (30% or more) sufficient to rotate the fan.

[0006]

[Problems to be solved by the invention]

 The present invention provides a control device for a heat dissipation system, and aims to protect a signal output by an external device electrically connected to the heat dissipation system from interference by a PWM signal that controls a voltage supply of the heat dissipation system. I do.

It is a further object of the present invention to provide an improved PWM control circuit for a DC fan.

[0008] It is another further object of the present invention to provide an improved PWM control circuit for a DC fan and to increase the duty cycle control ratio.

[0009]

[Means for Solving the Problems]

 The control device according to the present invention is a signal generator that is electrically connected between the heat dissipation system and a power supply that supplies a voltage to the heat dissipation system, generates a control signal, and switches on / off of the power supply; And a voltage regulator electrically connected between and connected to the signal generator and continuously providing the base voltage to the heat dissipation system; and an output of an external device electrically connected to the heat dissipation system. Prevent signals from being disturbed by control signals.

[0010] The signal generator is a PWM circuit, and the control signal is a PWM signal. The duty cycle of the PWM signal can vary without limit from 0% to 100%.

Further, the control device further includes an electronic switch electrically connected between the power supply and the heat dissipation system, is connected to the PWM circuit, receives the PWM signal, and responds to the duty cycle of the PWM signal. Controls the speed of the fan of the heat dissipation system. Preferably, the electronic switch is a transistor.

According to the invention, the voltage regulator is a zener diode, a resistor, a voltage supply for supplying a voltage lower than the voltage supplied by the power supply, or a circuit for providing a basic voltage to an external circuit in the heat dissipation system; Can be.

The external device includes a detector for detecting a rotation speed of the fan in the heat dissipation system, or a frequency generator for generating a square wave signal representing the rotation speed of the fan in the heat dissipation system.

[0014]

[Embodiment of the invention]

 In order to clarify the purpose, features and advantages of the present invention described above, preferred embodiments of the present invention will be described below with reference to the drawings.

FIG. 4 is a diagram showing a preferred embodiment of the control device used in the heat dissipation system according to the present invention. The heat dissipation system exemplifies a DC fan 41. The control device is electrically connected between the fan 41 and a voltage supply Vcc for supplying a voltage to the fan 41, generates a control signal, and turns on / off a signal generator 43; A voltage regulator that is electrically connected to the supply Vcc and is in parallel with the signal generator 1 and that continuously supplies the basic voltage to the fan 41; The output signal of the device is prevented from being disturbed by the control signal. The external device may include a detector (indicated by RD) that detects the rotational speed of the fan, or a frequency generator (indicated by FG) that generates a square wave signal that represents the rotational speed of the fan in the heat dissipation system. By designing such a control device, the RD signal output by the measuring instrument is maintained at a low potential under normal conditions, and is changed to a high potential only in abnormal conditions. Thus, the actual rotation speed of the fan can be accurately measured without being affected by the control signal. Similarly, corresponding to the actual rotational speed of the fan, the frequency generator generates a square wave signal having a constant frequency and is independent of the control signal.

The signal generator 43 is a PWM circuit, and is electrically connected between the voltage supply Vcc and the fan 41 via an electronic switch or a transistor 44 to generate a PWM signal (control signal). The PWM circuit changes the duty cycle of the PWM signal in response to the square wave signal generated by the frequency generator to further control the rotation speed of the fan.

The control circuit further comprises an electronic switch or transistor 44 electrically connected between the voltage supply Vcc and the fan, and is used to receive the PWM signal and controls the current flowing through the fan 41. I do. After receiving the PWM signal, the switching interval of transistor 44 will change due to the change in the duty cycle of the PWM signal, and the average current flowing through fan 41 will also change. Thus, the rotation speed of the fan 41 can be controlled by changing the duty cycle of the PWM signal. Furthermore, the duty cycle of the PWM signal can be limited to a range of 0% to 100%, unlike known circuits.

According to the present invention, the voltage regulator 42 provides a zener diode, a resistor, a voltage supply that supplies a voltage lower than the voltage supplied by the power supply, or a basic voltage to an external circuit in the heat dissipation system. Circuit. The main function of the voltage regulator 42 is to continuously provide the basic voltage to the external device of the fan, so that the signal output by the frequency generator or tachometer is not disturbed by the PWM signal. Thus, the actual rotation speed of the fan 41 can be measured.

The simplified control circuit of the heat dissipation system of the present invention prevents the output signal from an external device electrically connected to the heat dissipation system from being disturbed by the PWM signal used to control the voltage supply of the heat dissipation system. In addition to preventing, it also achieves the purpose of converting and controlling the rotation speed of the DC fan. Furthermore, the improved control circuit of the PWM signal of the present invention can increase the duty cycle control ratio of the PWM signal.

Although the preferred embodiments have been disclosed in the present invention as described above, they are not limited to the present invention in any way, and any person who is familiar with the technology does not depart from the spirit and scope of the present invention. Thus, various variations and colors can be added, and the protection scope of the present invention is based on the contents specified in the claims.

[0021]

[Effect of the invention]

 The signal output by an external device electrically connected to the heat dissipation system can be protected from interference by the PWM signal that controls the voltage supply of the heat dissipation system.

[Brief description of the drawings]

FIG. 1 is a diagram showing a known PWM control circuit used for a DC fan.

FIG. 2 is a diagram showing that a frequency generator electrically connected to a fan is obstructed by a PWM signal output by a known PWM control circuit.

FIG. 3 is a diagram showing that a rotational speed measuring device electrically connected to a fan is obstructed by a PWM signal output by a known PWM control circuit.

FIG. 4 is a view showing a preferred embodiment of a control device used in the heat dissipation system according to the present invention;

[Explanation of symbols]

 41 Fan 44 Transistor 42 Voltage regulator 43 Signal generator

Claims (8)

[Utility model registration claims] 1. A control device for a heat dissipation system, wherein the control device is electrically connected between the heat dissipation system and a power supply that supplies a voltage to the heat dissipation system, generates a control signal, and turns on / off the power supply. A signal generator for switching, and a voltage adjusting device electrically connected between the heat dissipating device and the power supply, arranged in parallel with the signal generator, and providing a basic voltage to the heat dissipating device. A control device for preventing an output signal of an external device electrically connected to the control signal from being disturbed by the control signal. 2. The control device according to claim 1, wherein said signal generator is a pulse width modulation PWM circuit. 3. The heat dissipation system electrically connected between the power supply and the heat dissipation system, connected to the PWM circuit, receiving the PWM signal, and corresponding to a duty cycle of the PWM signal. The control device according to claim 2, further comprising an electronic switch for controlling a rotation speed of the fan. 4. The control device according to claim 1, wherein the control signal is a pulse width modulation signal. 5. The control device according to claim 1, wherein the voltage regulator is a voltage source, and supplies a voltage lower than the voltage supplied by the voltage source. 6. The control device according to claim 1, wherein the voltage regulator is a circuit and provides a basic voltage to an external circuit of the heat dissipation system. 7. The control device according to claim 1, wherein the external device electrically connected to the heat dissipation system includes a measuring device for measuring a rotation speed of a fan of the heat dissipation system. 8. The apparatus of claim 1, wherein the external device that is electrically connected to the heat dissipation system comprises a frequency generator that generates a square wave signal representing a rotation speed of a fan of the heat dissipation system. Control device.