A fan speed regulating circuit

Abstract

The invention discloses a fan speed regulation circuit, including a feedback circuit for obtaining the motor temperature and adjusting the fan enable signal and then outputting it; a compensation circuit 1 for obtaining the fan enable signal and the fan speed and then outputting a level signal after comparison; and a compensation circuit 2 for obtaining the level signal and adjusting the fan speed. The invention realizes dynamic regulation, does not occupy DSP resources, uses a PWM control chip to adjust the fan PWM control signal, and then achieves the purpose of speed regulation, has a simple circuit, and requires fewer power devices; has a high switching frequency, is easy to be continuous in current, has fewer harmonics, and has relatively small losses and heat generation; has good low-speed performance, high steady-speed accuracy, and a wide speed regulation range; the power switch device works in a switching state, has a small conduction loss, and when the switching frequency is appropriate, the switching loss is also small, so the efficiency is high.

Description

Technical Field

[0001] The invention relates to the technical field of fans, and in particular to a fan speed regulating circuit. Background Art

[0002] When the inverter is working, the heat generated by the motor at high speed and low speed is different. If a traditional constant speed fan is used for heat dissipation, the heat generated by the motor at low speed is not high. The fan is cooled at rated speed, and the fan loss is large. Therefore, a speed-adjustable fan is required to adjust the speed according to the temperature change of the motor. The current speed adjustment methods are as follows:

[0003] First, the old-fashioned reactor is actually an autotransformer with taps (generally, autotransformers do not have taps), which can change different voltages, so that the fan has different speeds;

[0004] Second, the electronic speed regulator uses thyristor plus potentiometer to change the voltage, which is a stepless speed regulation;

[0005] Third, the frequency converter does not adjust the voltage, but changes the frequency of the alternating current, which also achieves the purpose of speed regulation.

[0006] The above speed regulation methods are inefficient and have large losses. Summary of the invention

[0007] The object of the present invention is to provide a fan speed regulating circuit.

[0008] To achieve the above object, the present invention provides the following technical solution: a fan speed regulation circuit, comprising:

[0009] Feedback circuit, used to obtain the motor temperature and adjust the fan enable signal before output;

[0010] Compensation circuit 1, used for obtaining a fan enable signal and a fan speed and then outputting a level signal after comparison; and

[0011] The second compensation circuit is used to obtain the level signal to adjust the fan speed.

[0012] Furthermore, the feedback circuit includes an optocoupler U4, resistors R14, R17, R16, R18, R19, capacitors C9 and C16. After the capacitor C9 is connected in parallel with R17, one end is connected to the input end of the optocoupler U4, and the other end is connected to the resistor R14. The fan enable signal is obtained through the resistor R14 and the capacitor C9. One end of the resistor R16 is connected to the output end of the optocoupler U4 through one end of R18, and the other end of the resistor R16 is connected to the parallel capacitor C16 and resistor R19.

[0013] Furthermore, the model of the optical coupler U4 is PS2561DL2-1.

[0014] Furthermore, the compensation circuit 1 includes resistors R28, R34, R35, R27, R29, R31, R22, capacitors C22, C21, a comparator U5A, and a MOS tube Q3. One end of the resistor R28 is connected to the feedback circuit, the other end of R28 is connected to the positive input end of the comparator U5A, one end of the resistor R35 is connected to the negative input end of the comparator U5A, one end of the capacitor C22 is connected between R28 and the comparator U5A, and the other end of the capacitor C22 is connected to the resistor R35 and the comparator through the resistor R34. The comparator U5A is connected between the capacitor C22 and the resistor R34, and the other end of the capacitor C21 is connected between the resistor R34 and the comparator U5A. The output end of the comparator U5A is connected to the gate of the MOS tube Q3 through the resistor R29. One end of the resistor R31 is connected between the resistor R29 and the MOS tube Q3, and the other end of the resistor R31 is connected to the source of the MOS tube Q3. The drain of the MOS tube Q3 is connected to the resistor R22. One end of the resistor R27 is connected between the resistor R29 and the comparator U5A.

[0015] Furthermore, the model of the comparator U5A is TL082IDR.

[0016] Furthermore, the compensation circuit 2 includes a PWM control chip U3, an operational amplifier U5B, resistors R7, R8, R32, a capacitor C15, MOS tubes Q1, and Q2. The output end of the PWM control chip U3 is connected to the MOS tube Q1, and the 4th and 8th pins of the PWM control chip U3 are connected through resistors R7, R8, and capacitor C15. The output end of the operational amplifier U5B is connected to the MOS tube Q2, and the resistor R32 is connected to the negative input end of the operational amplifier U5B.

[0017] Furthermore, the model of the PWM control chip U3 is UC2843AQD8RQ.

[0018] Furthermore, the operational amplifier U5B is TL082IDR.

[0019] It can be seen from the above technical solution that the present invention has the following beneficial effects:

[0020] The fan speed regulation circuit realizes dynamic regulation without occupying DSP resources. It uses PWM control chip to adjust the fan PWM control signal to achieve the purpose of speed regulation. The circuit is simple and requires few power devices. The switching frequency is high, the current is easy to be continuous, the harmonics are few, and the loss and heat are relatively small. The low-speed performance is good, the steady-speed accuracy is high, and the speed regulation range is wide. The power switching device works in the switching state, the conduction loss is small, and when the switching frequency is appropriate, the switching loss is not large, so the efficiency is high. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 This is the feedback circuit diagram of the present invention;

[0022] Figure 2 FIG1 is a diagram of a compensation circuit of the present invention;

[0023] Figure 3 FIG. 2 is a second diagram of the compensation circuit of the present invention. DETAILED DESCRIPTION

[0024] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0025] See also Figure 1-3 The present invention provides a fan speed control circuit, including a feedback circuit, a compensation circuit 1 and a compensation circuit 2, such as Figure 1 As shown, the feedback circuit includes an optocoupler U4, resistors R14, R17, R16, R18, R19, capacitors C9 and C16. After capacitor C9 is connected in parallel with R17, one end is connected to the input end of the optocoupler U4, and the other end is connected to resistor R14. The fan enable signal is obtained through resistor R14 and capacitor C9. One end of resistor R16 is connected to the output end of the optocoupler U4 through one end of R18, and the other end of resistor R16 is connected to capacitor C16 and resistor R19 connected in parallel.

[0026] R14 and R17 are current limiting resistors. The function of R17 is to ensure the minimum current required when the optocoupler is fully turned on. The function of C9 is filtering. R16 and C16 are RC filters. R16 and R19 divide the voltage. R19 is a voltage divider resistor. R18 is a pull-down resistor. When the optocoupler is not turned on, Vo is pulled down to ground. The fan enable signals FAN_EN and FAN_EN_G are square wave signals. The feedback circuit obtains the motor temperature, adjusts the square wave signal according to the motor temperature, and then outputs it.

[0027] like Figure 2As shown, compensation circuit 1 includes resistors R28, R34, R35, R27, R29, R31, R22, capacitors C22, C21, comparator U5A, and MOS tube Q3. One end of resistor R28 is connected to the feedback circuit, the other end of R28 is connected to the positive input end of comparator U5A, one end of resistor R35 is connected to the negative input end of comparator U5A, one end of capacitor C22 is connected between R28 and comparator U5A, and the other end of capacitor C22 is connected between resistor R35 and comparator U5A through resistor R34, and one end of capacitor C21 is connected to capacitor C2 2 and resistor R34, and the other end of capacitor C21 is connected between resistor R34 and comparator U5A, the output end of comparator U5A is connected to the gate of MOS tube Q3 through resistor R29, one end of resistor R31 is connected between resistor R29 and MOS tube Q3, and the other end of resistor R31 is connected to the source of MOS tube Q3, the drain of MOS tube Q3 is connected to resistor R22, one end of resistor R27 is connected between resistor R29 and comparator U5A, the model of optocoupler U4 is PS2561DL2-1, and the model of comparator U5A is TL082IDR;

[0028] R28 is a current limiting resistor, R34 and C21 are RC filters, R35 is a pull-up resistor, and R27 is a pull-up resistor. Connecting +13V is to ensure the integrity of the square wave. If +13V is not connected, the output of the op amp is a slow rising process. Comparator 2 and 3 pins compare the voltages. When the comparator 1 pin outputs a high level, the MOS tube Q3 is turned on and the COMP signal is pulled to the ground; when the comparator 1 pin outputs a low level, +13V is pulled to the ground, the MOS tube is not turned on, and the compensation circuit obtains the fan enable signal and the fan speed and then compares them to output a level signal. Specifically, when the fan speed is lower than the set value (fan enable signal), the output COMP is a high level, otherwise, it outputs a low level.

[0029] like Figure 3As shown, the compensation circuit 2 includes a PWM control chip U3, an operational amplifier U5B, resistors R7, R9, R8, R15, R13, R20, R21, R24, R25, R23, R26, R30, R32, R33, capacitors C8, C15, C13, C14, C11, C12, C10, C17, C19, C20, MOS tubes Q1 and Q2, and the output end of the PWM control chip U3 is connected to the MOS tube through R15 and R20. The source of Q1, the gate of MOS tube Q1 is connected between R15 and R20, the drain of MOS tube Q1 is connected to one end of R13, the 4th and 8th pins of PWM control chip U3 are connected through resistors R7, R8 and capacitor C15, C15, C13 and C14 are connected in parallel to the 4th pin of PWM control chip U3, one end of resistor R9 is connected between R8 and PWM control chip U3, and the other end of resistor R9 is connected to C13 through C8, capacitors C12 and C10 are connected in parallel. After being connected, it is connected to the 7th pin of the PWM control chip U3, the capacitor C11 is connected to the 8th pin of the PWM control chip U3, and C15, C13, C14, C11, C12, and C10 are connected in parallel; the resistor R21 is connected to the positive input terminal of the operational amplifier U5B through the resistor R25, the resistor R24 ​​is connected in parallel with the capacitor C17 and connected between R21 and R25, one end of the resistor R23 is connected between R25 and the operational amplifier U5B, and the other end is connected to the output terminal of the operational amplifier U5B, and the operational amplifier U5B is connected to the positive input terminal of the operational amplifier U5B. The output end of the operational amplifier U5B is connected to the gate of the MOS tube Q2 through the resistor R30, the drain of the MOS tube Q2 is connected to R13, the source and the gate of the MOS tube Q2 are connected through R33, one end of the resistor R26 is connected between R23 and R30, the resistor R32 is connected to the negative input end of the operational amplifier U5B, one end of the capacitor C19 is connected between R32 and the operational amplifier U5B, and the other end of the capacitor C19 is connected to the capacitor C20, and the capacitor C20 is connected to R25.

[0030] The model of PWM control chip U3 is UC2843AQD8RQ, the operational amplifier U5B is TL082IDR, R7 and R8 are timing resistors, C15 is a timing capacitor, R7, R8, and C15 form a frequency oscillator; FAN_PWM is the fan PWM wave control signal; R32 is a current limiting resistor.

[0031] When the fan speed is lower than the set value, COMP is high, and the internal compensation circuit of the PWM chip is started, so that the output duty cycle of the PWM chip becomes lower, and the off time of the MOS tube Q1 increases. At the same time, Vo is high, so that the output of the operational amplifier U5B is low, and the MOS tube Q2 is in the off state, that is, the MOS tube Q2 is not turned on, and the high-level fan PWM control signal is output. At this time, the fan speed becomes faster; when the fan speed is higher than the set value, COMP is low, and the internal compensation circuit of the PWM chip is turned off, the chip output duty cycle becomes higher, and the on time of the MOS tube Q1 increases. At the same time, Vo is low, so that the output of the operational amplifier U5B is high, and the MOS tube Q2 is in the on state, and the low-level fan PWM control signal is output. At this time, the fan speed slows down. The level signal is obtained through the compensation circuit 2 to adjust the fan speed.

[0032] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various 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 fan speed control circuit, It is characterized in that include: Feedback circuit, used to obtain the motor temperature and adjust the fan enable signal before output; Compensation circuit 1, used for obtaining the fan enable signal and the fan speed and then outputting a level signal after comparison; as well as Compensation circuit 2, used to obtain level signal to adjust fan speed; The feedback circuit includes an optocoupler U4, resistors R14, R17, R16, R18, R19, capacitors C9 and C16. After the capacitor C9 is connected in parallel with R17, one end is connected to the input end of the optocoupler U4, and the other end is connected to the resistor R14. The fan enable signal is obtained through the resistor R14 and the capacitor C9. One end of the resistor R16 is connected to the output end of the optocoupler U4 through one end of R18, and the other end of the resistor R16 is connected to the capacitor C16 and the resistor R19 connected in parallel; The compensation circuit 1 includes resistors R28, R34, R35, R27, R29, R31, R22, capacitors C22, C21, comparator U5A, and MOS tube Q3. One end of the resistor R28 is connected to the feedback circuit, and the other end of R28 is connected to the positive input end of the comparator U5A. One end of the resistor R35 is connected to the negative input end of the comparator U5A. One end of the capacitor C22 is connected between R28 and the comparator U5A, and the other end of the capacitor C22 is connected to the resistor R35 and the comparator U5 through the resistor R34. A, one end of the capacitor C21 is connected between the capacitor C22 and the resistor R34, and the other end of the capacitor C21 is connected between the resistor R34 and the comparator U5A, the output end of the comparator U5A is connected to the gate of the MOS tube Q3 through the resistor R29, one end of the resistor R31 is connected between the resistor R29 and the MOS tube Q3, and the other end of the resistor R31 is connected to the source of the MOS tube Q3, the drain of the MOS tube Q3 is connected to the resistor R22, and one end of the resistor R27 is connected between the resistor R29 and the comparator U5A; The compensation circuit 2 includes a PWM control chip U3, an operational amplifier U5B, resistors R7, R8, R32, a capacitor C15, MOS tubes Q1 and Q2. The output end of the PWM control chip U3 is connected to the MOS tube Q1, and the 4th and 8th pins of the PWM control chip U3 are connected through resistors R7, R8 and capacitor C15. The output end of the operational amplifier U5B is connected to the MOS tube Q2, and the resistor R32 is connected to the negative input end of the operational amplifier U5B.

2. A fan speed regulating circuit according to claim 1, Features: The model of the optical coupler U4 is PS2561DL2-1.

3. A fan speed regulating circuit according to claim 1, Features: The model of the comparator U5A is TL082IDR.

4. A fan speed regulating circuit according to claim 1, Features: The model of the PWM control chip U3 is UC2843AQD8RQ.

5. A fan speed regulating circuit according to claim 1, Features: The model of the operational amplifier U5B is TL082IDR.

Images