Control circuit for realizing speed regulation and speed measurement of fan

Abstract

The utility model relates to a control circuit for realizing speed regulation and speed measurement of a fan, which comprises a power supply unit, the fan, a charging and discharging unit, a signal control unit, a PWM signal source, a comparator U1 and a processor, and is characterized in that a positive pole FAN + of the fan is connected with an in-phase input end of the comparator U1, and a negative pole FAN-of the fan is connected with an inverted input end of the comparator U1; a speed measurement signal end FG of the fan is connected with the positive electrode of the power supply unit and the in-phase input end of the comparator U1, and if the voltage of the in-phase input end of the comparator U1 is larger than that of the inverted input end of the comparator U1, the comparator U1 outputs high level to the processor. The voltage of the in-phase input end of the comparator U1 is greater than that of the inverted input end of the comparator U1, and the comparator U1 outputs a low level to the processor; and the processor detects the rotating speed of the fan according to the level signal so as to realize the functions of speed regulation and speed measurement of the fan.

Description

Technical Field

[0001] The invention relates to the technical field of electronic circuits, and in particular to a control circuit for realizing fan speed regulation and speed measurement. Background Art

[0002] A two-wire DC fan speed adjustable control circuit is disclosed in a Chinese utility model patent publication number CN220342229 U. It can be seen from the technical solution that it can only realize the fan speed regulation function, but cannot realize the speed measurement function. Based on the defects of the existing technical solution, the inventor has developed a control circuit that can realize fan speed regulation and speed measurement. Summary of the invention

[0003] The present invention is to solve one of the above technical problems and provide a control circuit for realizing fan speed adjustment and speed measurement.

[0004] In order to solve the above technical problems, the present invention provides the following technical solutions:

[0005] A control circuit for realizing fan speed regulation and speed measurement comprises a power supply unit, a fan, a charge-discharge unit and a signal control unit, wherein the fan and the charge-discharge unit are both connected to the positive and negative poles of the power supply unit, the fan and the charge-discharge unit are connected in parallel, the signal control unit is connected to the charge-discharge unit, and the signal control unit is also externally connected to a PWM signal source and a ground; further comprising a comparator U1 and a processor, wherein the positive pole FAN+ of the fan is connected to the non-inverting input terminal of the comparator U1, the negative pole FAN- of the fan is connected to the inverting input terminal of the comparator U1, the speed measurement signal terminal FG of the fan is respectively connected to the positive pole of the power supply unit and the non-inverting input terminal of the comparator U1, if the voltage of the non-inverting input terminal of the comparator U1 is greater than the voltage of the inverting input terminal of the comparator U1, the comparator U1 outputs a high level to the processor; if the voltage of the non-inverting input terminal of the comparator U1 is less than the voltage of the inverting input terminal of the comparator U1, the comparator U1 outputs a low level to the processor; the processor detects the speed of the fan according to the level signal.

[0006] As a preferred implementation manner, it is further defined that the positive electrode FAN+ of the fan is connected to the non-inverting input terminal of the comparator U1 through a first voltage divider unit.

[0007] As a preferred embodiment, it is further defined that the first voltage divider unit includes resistors R5, R8 and R9, the positive electrode FAN+ of the fan is connected to resistors R8, R9 and R5 in sequence, the other end of the resistor R5 is grounded, the speed measurement signal terminal FG of the fan is connected to the connection node between resistors R8 and R9, and the non-inverting input terminal of the comparator U1 is connected to the connection node between resistors R5 and R9.

[0008] As a preferred implementation manner, it is further defined that the negative electrode FAN- of the fan is connected to the inverting input terminal of the comparator U1 through a second voltage divider unit.

[0009] As a preferred embodiment, it is further defined that the second voltage divider unit includes a resistor R6 and a resistor R7, the negative pole FAN- of the fan is connected to the resistor R6 and the resistor R7 in sequence, the other end of the resistor R7 is grounded, and the inverting input end of the comparator U1 is connected to the connection node between the resistor R6 and the resistor R7.

[0010] As a preferred implementation, it is further defined that the output terminal FANFA of the comparator U1 is connected to the processor through a protection unit.

[0011] As a preferred embodiment, it is further defined that the protection unit includes a resistor R3, a resistor R4 and a diode D1, the output end FANFA of the comparator U1 is respectively connected to one end of the resistor R3 and one end of the resistor R4, the other end of the resistor R3 is respectively connected to the processor and the cathode of the diode D1, and the other end of the resistor R4 and the anode of the diode D1 are both grounded.

[0012] As a preferred implementation, it is further defined that the charging and discharging unit includes a capacitor C1, an inductor L1 and a diode D1, the capacitor C1, the inductor L1 and the diode D1 are connected in sequence, the diode D1 is connected to the capacitor C1, and the positive and negative electrodes of the power supply unit are connected to the capacitor C1.

[0013] As a preferred embodiment, it is further defined that the signal control unit includes a resistor R1, a resistor R2 and a field effect transistor Q1, the resistor R1 is connected to the control electrode G of the field effect transistor Q1 and an external PWM signal source, one end of the resistor R2 is connected to the resistor R1 and the other end is connected to the ground, the source S of the field effect transistor Q1 is connected to the ground, and the drain D of the field effect transistor Q1 is connected to the inductor L1.

[0014] As a preferred implementation manner, it is further defined that the power supply unit is a 12V power supply, and the fan is a three-wire DC fan.

[0015] After adopting the above technical scheme, the invention has at least the following beneficial effects: a control circuit for realizing fan speed regulation and speed measurement, including a power supply unit, a fan, a charging and discharging unit, a signal control unit, a PWM signal, a comparator U1 and a processor, so as to realize the fan's speed regulation and speed measurement functions. The control circuit of the utility model has a simple structure, has no special PWM control requirements for the fan, has the advantages of low cost and high safety, and can meet market needs and improve product competitiveness. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1It is the principle block diagram of the control circuit;

[0017] Figure 2 This is the circuit schematic diagram of the control circuit to achieve fan speed measurement;

[0018] Figure 3 It is the circuit schematic diagram of the control circuit to realize fan speed regulation;

[0019] Figure 4 It is the waveform diagram of the input signal and output signal of the comparator U1 circuit. DETAILED DESCRIPTION

[0020] It should be noted that, in the absence of conflict, the embodiments in the present application and the features described in the embodiments may be combined with each other. The present application is further described in detail below in conjunction with the drawings and specific embodiments.

[0021] The utility model is based on a two-wire DC fan speed adjustable control circuit in the prior art (publication number CN220342229 U) and is further improved to achieve the fan speed adjustment and speed measurement functions, as follows.

[0022] As attached Figure 1 As shown, a control circuit for realizing fan speed regulation and speed measurement includes a power supply unit 1, a fan 2, a charge and discharge unit 3 and a signal control unit 4, wherein the power supply unit 1 is a 12V power supply, and the fan 2 is a three-wire DC fan 2; the fan 2 and the charge and discharge unit 3 are both connected to the positive and negative poles of the power supply unit 1, the fan 2 and the charge and discharge unit 3 are connected in parallel, the signal control unit 4 is connected to the charge and discharge unit 3, and the signal control unit 4 is also externally connected to a PWM signal source and a ground; the PWM signal source sends a PWM signal to the signal control unit 4, the signal control unit 4 is used to receive the PWM signal, and determines whether to charge or discharge according to the PWM signal, and the signal control unit 4 transmits the charging signal or the discharging signal to the charge and discharge unit 3;

[0023] Furthermore, the charge and discharge unit 3 is used to receive the charging signal of the signal control unit 4 and perform a charging action, thereby increasing the voltage of the fan 2; and, the charge and discharge unit 3 is used to receive the discharge signal of the signal control unit 4 and perform a discharge action, thereby reducing the voltage of the fan 2; the charge and discharge unit 3 is used to control the voltage of the fan 2 and thus control the speed of the fan 2.

[0024] Furthermore, it also includes a comparator U1 and a processor. The model of the comparator U1 is LM358. The positive pole FAN+ of the fan 2 is connected to the non-inverting input terminal of the comparator U1, and the negative pole FAN- of the fan 2 is connected to the inverting input terminal of the comparator U1. The speed measurement signal terminal FG of the fan 2 is respectively connected to the positive pole of the power supply unit 1 and the non-inverting input terminal of the comparator U1. If the voltage of the non-inverting input terminal of the comparator U1 is greater than the voltage of the inverting input terminal of the comparator U1, the comparator U1 outputs a high level to the processor; if the voltage of the non-inverting input terminal of the comparator U1 is less than the voltage of the inverting input terminal of the comparator U1, the comparator U1 outputs a low level to the processor; the processor detects the rotation speed of the fan 2 according to the level signal, and the comparator U1 is used to compare the voltage difference between the speed measurement signal terminal FG of the fan 2 and the negative pole of the fan, thereby outputting the level signal to the processor, and the processor can measure the rotation speed of the fan according to the frequency of the level signal, the waveform duty cycle, etc.

[0025] As attached Figure 1 and attached Figure 2 As shown, the positive electrode FAN+ of the fan 2 is connected to the non-inverting input terminal of the comparator U1 through the first voltage divider unit 5, the first voltage divider unit 5 includes a resistor R5, a resistor R8 and a resistor R9, the positive electrode FAN+ of the fan 2 is connected to the resistor R8, the resistor R9 and the resistor R5 in sequence, the other end of the resistor R5 is grounded, the speed measurement signal terminal FG of the fan 2 is connected to the connection node between the resistor R8 and the resistor R9, and the non-inverting input terminal of the comparator U1 is connected to the connection node between the resistor R5 and the resistor R9.

[0026] As attached Figure 1 and attached Figure 2 As shown, the negative electrode FAN- of the fan 2 is connected to the inverting input terminal of the comparator U1 through the second voltage dividing unit 6; the second voltage dividing unit 6 includes a resistor R6 and a resistor R7, the negative electrode FAN- of the fan 2 is connected to the resistor R6 and the resistor R7 in sequence, the other end of the resistor R7 is grounded, and the inverting input terminal of the comparator U1 is connected to the connection node between the resistor R6 and the resistor R7.

[0027] As attached Figure 1 and attached Figure 2As shown, the output end FANFA of the comparator U1 is connected to the processor through the protection unit 7, and the protection unit 7 includes a resistor R3, a resistor R4 and a diode D1. The output end FANFA of the comparator U1 is respectively connected to one end of the resistor R3 and one end of the resistor R4, and the other end of the resistor R3 is respectively connected to the processor and the cathode of the diode D1, and the other end of the resistor R4 and the anode of the diode D1 are both grounded; the resistor R4 is pulled down to the ground to play an anti-interference role, while the resistor R3 plays a current limiting role, and the diode D1 plays a voltage limiting role, thereby playing an effective circuit protection role.

[0028] As attached Figure 1 and attached Figure 3 As shown, the charging and discharging unit 3 includes a capacitor C1, an inductor L1 and a diode D1, the capacitor C1, the inductor L1 and the diode D1 are connected in sequence, the diode D1 is connected to the capacitor C1, and the positive and negative electrodes of the power supply unit 1 are connected to the capacitor C1; the signal control unit 4 includes a resistor R1, a resistor R2 and a field effect transistor Q1, the resistor R1 is connected to the control electrode G of the field effect transistor Q1 and the external PWM signal source, one end of the resistor R2 is connected to the resistor R1 and the other end is connected to the ground, the source electrode S of the field effect transistor Q1 is connected to the ground, and the drain electrode D of the field effect transistor Q1 is connected to the inductor L1. The fan voltage can be controlled by using a few simple components to control the fan speed; the control circuit of the utility model has a simple structure, no special PWM control requirements for the fan, and has the advantages of low cost and high safety.

[0029] As attached Figure 4 As shown in the figure, the specific working principle of speed control is as follows:

[0030] Set the voltage of the speed signal terminal FG of the fan 2 to V FG , set the negative pole FAN- voltage of the fan 2 to V FAN- , then the divided voltage at the non-inverting input of comparator U1 is V 同 =(R5*V FG ) / (R9+R5), the divided voltage at the inverting input of comparator U1 is V 反 =(R7*V FAN- ) / (R6+R7).

[0031] When the fan is in a stopped state, the voltage V FG Relative to the negative pole FAN- voltage V of fan 2 FAN- is 0 volts, at which point V 同 <V 反, that is, the voltage at the non-inverting input of comparator U1 is less than the voltage at the inverting input of comparator U1, so the output FANFA of comparator U1 is low level; when the fan is in rotation, the speed measurement signal terminal FG of fan 2 obtains a certain voltage, at this time V 同 >V 反 , that is, the voltage at the non-inverting input terminal of the comparator U1 is greater than the voltage at the inverting input terminal of the comparator U1, so the output terminal FANFA of the comparator U1 is high level, and the processor can measure the speed of the fan according to the frequency of the level signal, the waveform duty cycle, etc.

[0032] Therefore, the technical solution of the utility model can realize the functions of both speed adjustment and speed measurement of the fan, which not only meets the market needs but also improves the competitiveness of the product.

[0033] Although the embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various equivalent changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A control circuit for realizing fan speed regulation and speed measurement, comprising a power supply unit, a fan, a charge-discharge unit and a signal control unit, wherein the fan and the charge-discharge unit are connected to the positive and negative electrodes of the power supply unit, the fan and the charge-discharge unit are connected in parallel, the signal control unit is connected to the charge-discharge unit, and the signal control unit is also externally connected to a PWM signal source and a ground; characterized in that: It also includes a comparator U1 and a processor, the positive pole FAN+ of the fan is connected to the non-inverting input terminal of the comparator U1, the negative pole FAN- of the fan is connected to the inverting input terminal of the comparator U1, the speed measurement signal terminal FG of the fan is respectively connected to the positive pole of the power supply unit and the non-inverting input terminal of the comparator U1, if the voltage of the non-inverting input terminal of the comparator U1 is greater than the voltage of the inverting input terminal of the comparator U1, the comparator U1 outputs a high level to the processor; if the voltage of the non-inverting input terminal of the comparator U1 is less than the voltage of the inverting input terminal of the comparator U1, the comparator U1 outputs a low level to the processor; the processor detects the speed of the fan according to the level signal.

2. The control circuit according to claim 1, characterized in that: The positive electrode FAN+ of the fan is connected to the non-inverting input terminal of the comparator U1 through a first voltage divider unit.

3. The control circuit according to claim 2, characterized in that: The first voltage divider unit includes resistors R5, R8 and R9, the positive electrode FAN+ of the fan is connected to resistors R8, R9 and R5 in sequence, the other end of the resistor R5 is grounded, the speed measurement signal end FG of the fan is connected to the connection node between resistors R8 and R9, and the non-inverting input end of the comparator U1 is connected to the connection node between resistors R5 and R9.

4. The control circuit according to claim 1, characterized in that: The negative electrode FAN- of the fan is connected to the inverting input terminal of the comparator U1 through the second voltage dividing unit.

5. The control circuit according to claim 4, characterized in that: The second voltage dividing unit includes a resistor R6 and a resistor R7, the negative electrode FAN- of the fan is connected to the resistor R6 and the resistor R7 in sequence, the other end of the resistor R7 is grounded, and the inverting input end of the comparator U1 is connected to the connection node between the resistor R6 and the resistor R7.

6. The control circuit according to claim 1, characterized in that: The output terminal FANFA of the comparator U1 is connected to the processor through the protection unit.

7. The control circuit according to claim 6, characterized in that: The protection unit includes a resistor R3, a resistor R4 and a diode D1. The output end FANFA of the comparator U1 is connected to one end of the resistor R3 and one end of the resistor R4 respectively. The other end of the resistor R3 is connected to the processor and the cathode of the diode D1 respectively. The other end of the resistor R4 and the anode of the diode D1 are grounded.

8. The control circuit according to any one of claims 1 to 7, characterized in that: The charging and discharging unit includes a capacitor C1, an inductor L1 and a diode D1, which are connected in sequence, the diode D1 is connected to the capacitor C1, and the positive and negative electrodes of the power supply unit are connected to the capacitor C1.

9. The control circuit according to claim 8, characterized in that: The signal control unit includes a resistor R1, a resistor R2 and a field effect transistor Q1, the resistor R1 is connected to the control electrode G of the field effect transistor Q1 and an external PWM signal source, one end of the resistor R2 is connected to the resistor R1 and the other end is connected to the ground, the source S of the field effect transistor Q1 is connected to the ground, and the drain D of the field effect transistor Q1 is connected to the inductor L1.

10. The control circuit according to any one of claims 1 to 7, characterized in that: The power supply unit is a 12V power supply, and the fan is a three-wire DC fan.

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